JP2013027972A - Square end mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a square end mill suppressing chipping over the entire area of outer peripheral blades and improving stability of performance in use.SOLUTION: In the square end mill including a plurality of bottom blades and outer peripheral blades, distal end cutting blade sections in which the radius of curvature of a ridge line formed by a flank of the outer peripheral blade and a cutting face of the outer peripheral blade is large are arranged on the distal end side of the outer peripheral blades, rear end cutting blades in which the radius of curvature is small are arranged on the rear end side of the outer peripheral blades, and the flank of the outer peripheral blade and the cutting face of the outer peripheral blade in each outer peripheral blade are formed of one curved surface, respectively.

Description

  The present invention relates to a new and high-performance square end mill with an improved blade shape that is useful for machine tools and the like, and is particularly useful for cutting a mold that is easy to weld and has high material hardness and poor machinability. It relates to a square end mill.

  Hard film coated tools such as end mills are widely used in mold processing and parts processing. On the other hand, with respect to the work material to be cut, performance improvement as a mold and as a part is progressing. For example, in the case of plastic mold materials, if the number of shots increases during injection molding, cracks occur in the mold, and the mold needs to be corrected. Improvements have been made to extend the time until the occurrence of cracking of the mold, and the material itself tends to have toughness while maintaining its strength as a conventional mold. That is, a metal material having both high hardness and high toughness such as HPM-MAGIC (registered trademark) has become common. In terms of parts processing, lightweight and high-strength materials are required, and materials that can sufficiently withstand strong impacts have been developed.

  In cutting using a general machine tool, the tool body rotates, and the cutting edge ridge line of the tool plastically deforms the work material to shear and discharge chips. At that time, the sheared chips are discharged through the rake face of the tool, and the flank proceeds while rubbing the work material, so that the finished surface is formed by rubbing the flank. However, it is formed from the rake face and the flank surface in the cutting of molds and parts by metal materials that have both high hardness and high toughness, such as the recently developed plastic mold materials as mentioned above. There arises a problem that the hard film peels off from the ridge line portion to be formed, or chipping of the ridge line portion due to the impact of cutting occurs. In particular, in a square end mill, a corner portion is formed at the connecting portion between the bottom blade and the outer peripheral blade, so that the ridge line portion tends to be chipped.

In order to improve the chipping resistance and the strength of the cutting edge, several proposals have been made for these problems.
In Patent Document 1, honing is performed such that the radius of curvature of the arc located at the boundary between the rake face and the flank face of the cutting edge continuously decreases from the front end side to the rear end side of the end mill body. A square end mill is described.
Patent Document 2 describes a throw-away tip provided with a reinforced portion having a large radius of curvature of the cutting edge on the tool base end side.
Furthermore, Patent Document 3 describes a square end mill in which at least a part of the coating is removed after coating.
Patent Document 4 describes a pin-cad type square end mill in which a cutting edge process is applied to the very tip of the cutting edge, and the rake face and the flank face in the vicinity of the edge of the cutting edge are chamfered.

JP 2009-45704 PR JP 2002-52415 PR JP 2000-107926 A JP-A-6-31520

  However, the ones that have been proposed and put to practical use perform contour cutting that mainly cuts the bottom blade with a long protruding amount, side cutting when the axial cut is large, and high-efficiency machining. Since the chipping resistance of the tool at that time was not ensured, there was a problem that it was not possible to sufficiently cope with maintaining a stable wear state and a machined surface state in long-time cutting.

  The square end mill described in Patent Document 1 has a configuration in which the radius of curvature of the ridge line in the outer peripheral blade continuously decreases from the front end side to the rear end side of the end mill, so that chipping can be suppressed on the front end side of the end mill. If the radius of curvature on the tip side is increased, it will not be possible to secure the sharpness on the tip side of the end mill, so chatter vibration will occur when side cutting is performed when the axial cut is increased, and after the end mill on the outer peripheral blade Chipping occurs on the end side.

  The throw-away tip described in Patent Document 2 is provided with a reinforced portion having a large radius of curvature of the cutting edge on the tool base end side, and therefore the cutting resistance is sharp in cutting at the reinforced portion provided on the tool base end side. This causes a problem that chatter vibration occurs.

  The square end mill described in Patent Document 3 has a problem in that the entire outer peripheral blade becomes dull and chipping and chatter vibration are likely to occur.

  Moreover, in patent document 4, since it is a pin-cad type square end mill which performed the blade edge process to the very front-end | tip part of the cutting edge, the cutting edge of a rear-end part remains the sharp edge which has not performed the cutting edge process. Therefore, there is a problem that an abrupt step is generated at the boundary between the tip portion subjected to the blade edge processing and the rear end portion not subjected to the blade edge processing in the cutting edge, and chipping is likely to occur at the boundary portion.

  In the cutting of the square end mill, the largest load is applied to the corner portion and the influence of vibration occurs most, so that chipping is likely to occur. This problem is similar not only in the case of side milling but also in the case of contour line machining. As for the use side, the timing at which chipping occurs even in the same tool varies depending on the state of vibration, and it is difficult to manage the tool life. In particular, when cutting a material that is easily welded, it is more difficult to cut the material stably without causing chipping.

  As mentioned above, there are various square end mills based on cemented carbide as cutting tools for stable processing of materials that are particularly easy to weld and have high material hardness and poor machinability without causing chipping. Proposed and put to practical use. However, since a square end mill with a cutting edge ridge shape that improves the stability of contour processing and shallow groove cutting has not been realized, the life varies with long-term cutting or multiple evaluations, and stable wear conditions However, it was not possible to sufficiently cope with maintaining the machined surface condition, and the problem remained.

  An object of the present invention is to provide a square end mill that can stably perform cutting without chipping even during long-time cutting or multiple cutting, and that can obtain a good finished surface from the beginning. is there.

  When contour finishing is performed with a square end mill, it is desirable that the corner portion does not cause chipping even after long-time machining from the beginning of cutting, and that it is possible to maintain a high-quality machined surface with a small change in surface roughness of the machined surface. Therefore, it is necessary to consider the radius of curvature of the edge of the cutting edge that is most suitable for the bottom edge and the outer peripheral edge mainly at the corner where the cutting load is most applied. Specifically, it is necessary to apply the optimum curvature of the edge of the cutting edge suitable for each part of the square end mill.

  In order to solve these problems, the present invention provides the curvature of the edge edge line of the intersection of the flank and rake face of the square blade that can stabilize the tool life and maintain a high-quality machining surface for a long time. It was examined in places.

  That is, the first aspect of the present invention is a square end mill having a plurality of bottom blades and outer peripheral blades, and a ridge line formed by a flank surface of the outer peripheral blades and a rake face of the outer peripheral blades on the distal end side of the outer peripheral blades. A cutting edge portion having a large curvature radius is provided, and a rear edge cutting edge portion having a small curvature radius is provided on the rear end side of the outer peripheral blade. The rake face is a square end mill characterized in that each rake face is formed by one curved surface.

  According to a second aspect of the present invention, in the first aspect of the present invention, the length of the tip cutting edge portion is a region from the joint of the bottom blade and the outer peripheral blade to 30% of the blade diameter.

  The third aspect of the present invention is characterized in that, in the first or second aspect of the present invention, the curvature radius R1 of the tip cutting edge portion is 2 μm or more and 4 μm or less, and the curvature radius R2 of the trailing edge cutting edge portion is 1 μm or more and 3 μm or less. End mill.

  The fourth aspect of the present invention is the curvature radius of the inner peripheral cutting edge portion that forms from the tool axis to a position of 25% of the blade diameter in the bottom blade in any one of the first to third aspects of the present invention. Ra is 1 μm or more and 2 μm or less, and the curvature radius Rb of the outer peripheral cutting edge portion forming from the outer periphery to the position of 25% of the blade diameter of the bottom blade is 4 μm or more and 6 μm or less. End mill.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, a blade portion having a plurality of bottom blades and an outer peripheral blade, a shank portion having a diameter larger than the blade portion, the blade portion, It is a square end mill characterized by being comprised from the neck part which connects a shank part.

  By applying the present invention, it is possible to suppress the occurrence of chipping in the entire outer peripheral edge even in side cutting when the axial cut in the state of a long protruding amount is increased, and stable cutting without chatter vibration Is possible.

  With the configuration of the outer peripheral blade as in the present invention, the stability of the performance is improved, the variation in performance when the same machining is performed with a plurality of pieces is suppressed, the life management is easy, and the quality of the machined surface is improved. It is possible to provide a square end mill that can be improved.

  By adopting the configuration of the bottom blade as in the present invention, chatter vibration can be suppressed even in contour cutting in which the bottom blade is mainly cut with a long protruding amount. Can be further suppressed.

  By configuring the outer peripheral blade as in the present invention, a blade portion having a plurality of bottom blades and outer peripheral blades, a shank portion having a diameter larger than the blade portion, and a neck portion connecting the blade portion and the shank portion Even in a square end mill configured from the above, it is possible to suppress chipping of the blade portion whose rigidity is relatively small with respect to the shank portion having a large diameter, and the blade diameter is in the range of 0.05 mm to 3.0 mm. Even in the case of a small diameter, the above advantageous effects can be obtained.

It is a front view which shows schematic structure of the square end mill which is an example of this invention. It is a figure which shows schematic structure of the long neck square end mill which is an example of this invention. It is an enlarged view of the connection part vicinity of the bottom blade and outer periphery blade in this invention. It is an enlarged view of the connection part vicinity of the bottom blade and outer periphery blade in the conventional end mill. It is an enlarged view of AA sectional drawing in FIG. It is an enlarged view of BB sectional drawing in FIG. It is an enlarged view of CC sectional drawing in FIG. It is an enlarged view of DD sectional drawing in FIG. It is the enlarged view which rotated the left view in FIG. 2 90 degrees in the tool rotation direction. FIG. 10 is an enlarged view of FIG. 9. It is an enlarged view of EE sectional drawing in FIG. It is an enlarged view of FF sectional drawing in FIG. It is an enlarged view of the vicinity of the connecting portion between the bottom blade and the outer peripheral blade in Conventional Example 2. It is the schematic of the barrel grinding | polishing apparatus implemented by this invention whose rotating shaft is 3 axis | shaft structure. It is a figure when the barrel polisher shown in FIG. 14 is seen from the lower side in FIG.

  The present invention is a square end mill for the purpose of suppressing chipping over the entire outer peripheral blade and improving the stability of performance during use. Hereinafter, embodiments for carrying out the present invention will be described with reference to FIGS.

  FIG. 1 is a front view showing a schematic configuration of a square end mill which is an example of the present invention. A square end mill 1 according to the present invention includes a plurality of bottom blades 2, an outer peripheral blade 3, and a shank portion 4. A square end mill 1 shown in FIG. 1 has a blade diameter D that is a diameter of a blade portion 6 having a plurality of bottom blades 2 and outer peripheral blades 3 and a shank diameter d that is a diameter of a shank portion 4 connected to the blade portion. It is designed with a shape with equal values.

  FIG. 2 is a front view showing a schematic configuration of a long neck square end mill which is an example of the present invention. A long neck square end mill 5 according to the present invention connects a blade portion 6 having a plurality of bottom blades 2 and an outer peripheral blade 3, a shank portion 4 having a diameter larger than that of the blade portion 6, and the blade portion 6 and the shank portion 4. The neck portion 8 is configured. As described above, the long neck square end mill 5 shown in FIG. 2 has a shank having a diameter of the shank portion 4 rather than the value of the blade diameter d which is the diameter of the blade portion 6 having the plurality of bottom blades 2 and the outer peripheral blades 3. It is designed with a shape in which the value of the diameter D is increased.

FIG. 3 is an enlarged view of the vicinity of the connecting portion between the bottom blade and the outer peripheral blade in the present invention. The outer peripheral blade 3 includes a flank 10 of the outer peripheral blade, a rake face 11 of the outer peripheral blade, and a cutting edge ridge line 12 of the outer peripheral blade. Further, a tip cutting edge portion 19 having a large radius of curvature of the edge edge 12 of the outer peripheral edge formed by the flank 10 of the outer peripheral edge and the rake face 11 of the outer peripheral edge is provided on the front end side of the outer peripheral edge 3. 3 is provided with a rear end cutting edge portion 20 having a small curvature radius. Although not shown, the rear end cutting edge portion 20 is formed from the boundary between the front end cutting edge portion 19 and the rear end cutting edge portion 20 to the end portion on the shank portion side of the blade portion.
In addition, the AA sectional line in the drawing is cut in a direction perpendicular to the outer peripheral blade 3 at a position away from the connecting portion of the bottom blade 2 and the outer peripheral blade 3 in the direction of the tool axis O by 20% of the blade diameter d. The cross-sectional line is shown. Similarly, the BB cross section line is a cross section when cutting in a direction perpendicular to the outer peripheral blade 3 at a position away from the connecting portion of the bottom blade 2 and the outer peripheral blade 3 in the direction of the tool axis O by 60% of the blade diameter d. A line is shown.

FIG. 4 is an enlarged view of the vicinity of a connecting portion between a bottom blade and an outer peripheral blade in a conventional end mill. The outer peripheral blade 3 in the conventional end mill 21 includes a flank 13 of the outer peripheral blade in the conventional end mill, a rake face 14 of the outer peripheral blade in the conventional end mill, and a cutting edge line 15 of the outer peripheral blade in the conventional end mill. Unlike the present invention, the conventional end mill 21 has a constant radius of curvature of the edge edge 15 of the outer peripheral edge of the conventional end mill over the entire area of the outer edge 3. Further, the radius of curvature of the edge edge 15 of the outer edge of the conventional end mill is as follows. 3 is smaller than the radius of curvature of the rear end cutting edge portion 20 on the rear end side of the outer peripheral blade 3 in the present invention shown in FIG.
In addition, the CC sectional line in the drawing is cut in a direction perpendicular to the outer peripheral blade 3 at a position away from the connecting portion of the bottom blade 2 and the outer peripheral blade 3 in the direction of the tool axis O by 20% of the blade diameter d. The cross-sectional line is shown. Similarly, the DD cross-sectional line is a cross section when cutting in a direction perpendicular to the outer peripheral blade 3 at a position away from the connecting portion of the bottom blade 2 and the outer peripheral blade 3 in the direction of the tool axis O by 60% of the blade diameter d. A line is shown.

That is, the outer peripheral blade 3 provided in the present invention is provided with the tip cutting edge portion 19 and the rear end cutting edge portion 20 which are two regions clearly distinguished by the difference in the curvature radius of the edge ridge line 12 of the outer peripheral blade. This is a major feature. As a result, even in side cutting when the axial cut in the state of a long protruding amount is increased, occurrence of chipping in the entire outer peripheral blade can be suppressed, and stable cutting can be performed without chatter vibration. On the other hand, the peripheral edge 3 in the conventional end mill does not have a plurality of regions clearly distinguished by the difference in the radius of curvature of the edge edge 12 of the peripheral edge as described above.
From these facts, it can be said that the structure of the edge edge line 12 of the outer peripheral edge in the present invention is clearly different from the structure of the edge edge line 15 of the outer edge in the conventional end mill.

  The curvature radius of the edge ridgeline of the outer peripheral edge, which is an important element of the present invention, will be described with reference to FIGS. The curvature radius of the edge edge line of the outer peripheral edge in the present invention is a radius formed at a portion where the flank and the rake face intersect when cut in a direction perpendicular to the outer peripheral edge of the square end mill in FIGS. 3 and 4. It is.

  FIG. 5 is an enlarged view of the AA cross-sectional view in FIG. 3. The AA cross-sectional view is a cross-sectional observation view when the tip cutting edge portion 19 of the outer peripheral blade 3 is cut in a direction perpendicular to the outer peripheral blade 3. The outer peripheral blade in the tip cutting edge portion 19 is composed of a flank 10 of the outer peripheral blade, a rake face 11 of the outer peripheral blade, and a cutting edge ridge line 12 of the outer peripheral blade. The edge edge line 12 of the outer peripheral edge in the tip cutting edge portion 19 is formed in an arc shape with the radius of curvature R1 of the tip cutting edge portion as a radius.

  6 is an enlarged view of the BB cross-sectional view in FIG. The BB cross-sectional view is a cross-sectional observation view when the rear end cutting edge portion 20 of the outer peripheral blade 3 is cut in a direction perpendicular to the outer peripheral blade 3. The outer peripheral blade in the rear end cutting edge portion 20 includes a flank 10 of the outer peripheral blade, a rake face 11 of the outer peripheral blade, and a cutting edge ridge line 12 of the outer peripheral blade. The edge edge line 12 of the outer peripheral edge in the rear end cutting edge portion 20 is formed in an arc shape with the radius of curvature R2 of the rear end cutting edge portion as a radius. In the present invention, the curvature radius R2 of the rear end cutting edge is set to be smaller than the curvature radius R1 of the front end cutting edge.

  7 is an enlarged view of the CC cross-sectional view in FIG. The CC cross-sectional view is perpendicular to the outer peripheral blade 3 at a position away from the joint between the bottom blade 2 and the outer peripheral blade 3 in the conventional end mill 21 shown in FIG. It is a cross-sectional observation figure when cut | disconnecting in an arbitrary direction. The outer peripheral blade 3 in the conventional end mill 21 includes a flank 13 of the outer peripheral blade in the conventional end mill, a rake face 14 of the outer peripheral blade in the conventional end mill, and a cutting edge line 15 of the outer peripheral blade in the conventional end mill. The edge ridge line 15 of the outer peripheral edge in the conventional end mill is formed in an arc shape with the radius of curvature R3 of the outer peripheral edge in the conventional end mill as a radius.

  FIG. 8 is an enlarged view of a DD cross-sectional view in FIG. 4. The DD cross-sectional view is perpendicular to the outer peripheral blade 3 at a position away from the joint between the bottom blade 2 and the outer peripheral blade 3 in the conventional end mill 21 shown in FIG. 4 in the direction of the tool axis O by 60% of the blade diameter d. It is a cross-sectional observation figure when cut | disconnecting in an arbitrary direction. As shown in FIG. 4, the curvature radius R <b> 3 of the outer peripheral blade in the conventional end mill is constant over the entire area of the outer peripheral blade 3. Therefore, in the present invention, the radius of curvature of the outer peripheral blade does not change even at the location corresponding to the rear end cutting edge portion 20, and the edge edge line 15 of the outer peripheral blade in the conventional end mill has the radius of curvature R3 of the outer peripheral blade in the conventional end mill as the radius. It is formed in the arc shape. Furthermore, the curvature radius R3 of the outer peripheral blade in the conventional end mill is smaller than the curvature radius R2 of the rear end cutting edge portion on the rear end side of the outer peripheral blade 3 in the present invention.

  As described above, in the present invention, the distal end cutting edge portion 19 having a large radius of curvature of the ridge formed by the flank 10 of the outer peripheral blade and the rake face 11 of the outer peripheral blade is provided on the distal end side of the outer peripheral blade. A rear end cutting edge portion 20 having a small curvature radius is provided on the rear end side of the outer peripheral edge, and the flank 10 of the outer peripheral edge and the rake face 11 of the outer peripheral edge of each outer peripheral edge are formed by one curved surface. Suppose that it is formed. Accordingly, chipping on the front end side of the outer peripheral blade 3 involved in cutting by contour line processing can be suppressed, and the rear end cutting edge portion 20 having an appropriate curvature radius is provided on the rear end side of the outer peripheral blade 3. Therefore, the processing surface is not damaged, and the blade edge itself can suppress abnormal wear such as chipping.

  When the radius of curvature R1 of the leading edge and the radius of curvature R2 of the trailing edge are the same, the tip strength of the outer peripheral edge involved in cutting is not ensured and chipping occurs. When chipping occurs at the tip side of the outer peripheral blade, it also affects the rear end side of the outer peripheral blade, causing damage to the entire outer peripheral blade and deterioration of the machined surface.

Further, even when the curvature radius R2 of the rear edge cutting edge is larger than the curvature radius R1 of the front edge cutting edge, the edge strength on the front edge side involved in cutting is not ensured and chipping occurs. On the rear end side of the outer peripheral blade having a large radius of curvature, when slight vibration occurs, the resistance when coming into contact with the processing surface increases, causing damage to the entire edge of the cutting edge and deterioration of the processing surface.
Therefore, in order to suppress chipping and stabilize the machining surface, the curvature radius R2 of the rear end cutting edge portion is smaller than the curvature radius R1 of the front end cutting edge portion at the front end side of the outer peripheral blade and the rear end side of the outer peripheral blade. There is a need to.

In the present invention, it is desirable that the length of the tip cutting edge portion 19 is 30% of the blade diameter d from the connecting portion of the bottom blade 2 and the outer peripheral blade 3 when measured in the direction of the tool axis O. By doing so, the strength of the edge of the part involved in cutting in the contour line processing is ensured, and the effect of suppressing chipping can be brought about.
Conversely, if the length of the tip cutting edge portion 19 is larger than 30% of the blade diameter d from the connecting portion of the bottom blade 2 and the outer peripheral blade 3 when measured in the direction of the tool axis O, a region having a large curvature radius is formed. Since it spreads to the rear end side of the outer peripheral blade, the resistance when contacting with the machined surface when slight vibration occurs increases, and it is confirmed that the entire edge of the blade edge is damaged and the machined surface is deteriorated. .

  Therefore, it is desirable that the length of the tip cutting edge portion 19 is 30% of the blade diameter from the connecting portion of the bottom blade 2 and the outer peripheral blade 3 when measured in the direction of the tool axis O. As a more preferable length of the leading edge 19, the boundary between the leading edge 19 and the trailing edge 20 is located at a position that is 10% or more and 30% or less of the blade diameter from the joint between the bottom edge and the outer edge. The tip edge side from the boundary is the tip edge portion 19 that is formed in an arc shape with the radius of curvature R1 of the tip cutting edge portion as the edge edge line 12 of the outer peripheral edge.

In the present invention, it is desirable that the radius of curvature R1 of the tip cutting edge portion is 2 μm or more and 4 μm or less. As a result, it is possible to achieve both the securing of the cutting edge strength capable of suppressing chipping and the machinability capable of obtaining a good machined surface.
When the radius of curvature R1 of the cutting edge of the tip is less than 2 μm, the strength of the blade edge is not ensured, and when cutting a hard material or machining under high efficiency conditions such as high speed cutting, a tendency for early chipping is confirmed. The Further, when the radius of curvature R1 of the tip cutting edge is larger than 4 μm, the cutting performance is slightly inferior, so that the cutting resistance is large and the vibration during cutting is also large. This confirms the tendency of chipping of the cutting edge to deteriorate the machined surface.
Therefore, it is desirable that the radius of curvature R1 of the tip cutting edge is 2 μm or more and 4 μm or less. It is further desirable that the radius of curvature R1 of the tip cutting edge is 2.5 μm or more and 3.5 μm or less.

In the present invention, it is desirable that the radius of curvature R2 of the rear end cutting edge is 1 μm or more and 3 μm or less. By doing so, even when minute chatter vibration or deflection that occurs during cutting occurs, the strength of the cutting edge is sufficiently ensured and the cutting resistance is also suppressed, so that the processed surface can be formed well.
When the radius of curvature R2 of the trailing edge cutting edge is less than 1 μm, the edge strength is not sufficient, and therefore, a tendency that chipping is likely to occur when minute chatter vibration or deflection occurs during cutting is confirmed. If this happens, it will naturally lead to deterioration of the machined surface. Conversely, if the radius of curvature R2 of the trailing edge is greater than 3μm, when the small chatter vibration or deflection that occurs during cutting occurs, the resistance when contacting the machined surface increases, resulting in damage to the entire edge of the cutting edge. The tendency to cause deterioration of the machined surface due to is confirmed.
Therefore, it is desirable that the radius of curvature R2 of the rear end cutting edge is 1 μm or more and 3 μm or less. It is further desirable that the radius of curvature R2 of the rear end cutting edge is 1.5 μm or more and 2.5 μm or less.

  FIG. 9 is an enlarged view of the left side view in FIG. 2 rotated 90 degrees in the tool rotation direction. As shown in FIGS. 2 and 9, the bottom blade 2 includes a bottom blade flank 16, a bottom blade rake surface 18, and a bottom edge ridge line 17.

  FIG. 10 is an enlarged view of FIG. The curvature radius of the cutting edge ridge line of the bottom blade 2 in the present invention is the bottom blade flank 16 and the bottom blade when the bottom blade 2 of the long neck square end mill in FIG. 9 is cut in a direction perpendicular to the bottom blade 2. It is a radius of curvature formed at a portion where the rake face 18 intersects. The EE cross-section line shown in FIG. 10 is a direction perpendicular to the bottom blade 2 at a position away from the connecting portion between the bottom blade and the outer peripheral blade in a direction perpendicular to the tool axis O by 10% of the blade diameter d. A cross-sectional line when cut is shown. The FF cross-sectional line indicates a cross-sectional line when cutting in the direction perpendicular to the bottom blade 2 at a position away from the tool axis O by 15% of the blade diameter d in the direction perpendicular to the tool axis O. .

  As shown in FIG. 10, in the outer peripheral side of the bottom blade 2 in the present invention, that is, in the region from the outer periphery to a position of 25% of the blade diameter, the bottom blade flank 16 and the bottom blade rake surface 18 intersect. An outer peripheral cutting edge portion 23 having a large curvature radius of the cutting edge ridge line 17 of the bottom blade is provided. In the inner peripheral side of the bottom blade 2, that is, a region from the tool axis to a position of 25% of the blade diameter, the curvature radius is A small inner peripheral cutting edge 22 is provided.

  FIG. 11 is an enlarged view of the EE cross-sectional view in FIG. 10. The EE cross-sectional view is a cross-sectional observation view when the outer peripheral cutting edge portion 23 of the bottom blade 2 shown in FIG. 10 is cut in a direction perpendicular to the bottom blade 2. The bottom blade in the outer peripheral cutting edge portion 23 includes a bottom blade flank 16, a bottom blade rake surface 18, and a bottom edge ridge line 17. The edge edge line of the bottom edge of the outer peripheral cutting edge portion 23 is formed in an arc shape with the radius of curvature Rb of the outer peripheral cutting edge portion as a radius.

  12 is an enlarged view of the FF cross-sectional view in FIG. FF sectional drawing is a cross-sectional observation figure when it cut | disconnects in the direction perpendicular | vertical to the bottom blade 2 in the inner peripheral cutting edge part 22 in the bottom blade 2 shown in FIG. The bottom blade in the inner peripheral cutting edge portion 22 includes a bottom blade flank 16, a bottom blade rake surface 18, and a bottom edge ridge line 17. The edge edge line of the bottom edge of the inner peripheral cutting edge portion 22 is formed in an arc shape with the radius of curvature Ra of the inner peripheral cutting edge portion as a radius.

In the present invention, it is desirable that the radius of curvature Ra of the inner peripheral cutting edge portion of the bottom blade 2 that forms a position away from the tool axis O by 25% of the blade diameter d is 1 μm or more and 2 μm or less. By doing so, the cutting resistance does not increase when the bottom cutting is performed, and the processing surface is not damaged. In addition, this makes it possible to obtain a high-quality processed surface. When the radius of curvature Ra of the inner peripheral cutting edge is less than 1 μm, the strength of the cutting edge is not ensured, and a tendency for chipping to occur is confirmed if even a small amount of chips generated during bottom cutting are caught. On the other hand, when the curvature radius Ra of the inner peripheral cutting edge exceeds 2 μm, it is confirmed that the cutting resistance increases, the chip discharging property deteriorates, and the tendency of chipping and deterioration of the processed surface occurs.
Therefore, it is desirable that the curvature radius Ra of the inner peripheral cutting edge portion of the bottom blade 2 is 1 μm or more and 2 μm or less. More preferably, the radius of curvature Ra of the inner peripheral cutting edge is 1.2 μm or more and 1.8 μm or less.

In the present invention, the curvature radius Rb of the outer peripheral cutting edge portion that forms the bottom blade 2 from the connecting portion of the bottom blade and the outer peripheral blade to a position separated by 25% of the blade diameter is 4 μm or more and 6 μm or less. It is desirable. By doing so, the cutting edge strength is ensured at the time of bottom cutting, so that stable machining can be performed without chipping, and a good machined surface can be obtained. When the curvature radius Rb of the outer peripheral cutting edge portion of the bottom blade 2 is less than 4 μm, the strength of the blade edge is not ensured at the time of bottom surface cutting, and a tendency to easily cause chipping is confirmed. This tendency is particularly noticeable during high-hardness machining and high-efficiency cutting. On the other hand, when the radius of curvature Rb of the outer peripheral cutting edge of the bottom edge exceeds 6 μm, cutting resistance increases and chip separation may be worsened. If this happens, the machined surface will deteriorate and chipping will occur, so stable machining cannot be realized.
Therefore, it is desirable that the curvature radius Rb of the outer peripheral cutting edge portion of the bottom blade 2 is 4 μm or more and 6 μm or less. It is further desirable that the radius of curvature Rb of the outer peripheral cutting edge is 4.5 μm or more and 5.5 μm or less.

  The present inventor pays attention to the flank and rake face and cutting edge ridgeline in the outer peripheral edge of the square end mill, and the cutting edge ridgeline that is optimum for the strength and machinability of the cutting edge ridgeline at the front end side and the rear end side of the outer peripheral edge The state was examined. As a result, a tip cutting edge portion having a large radius of curvature of a ridge formed by the flank of the outer peripheral blade and the rake face of the outer peripheral blade is provided on the front end side of the outer peripheral blade, and on the rear end side of the outer peripheral blade. A cutting edge portion having a small radius of curvature is provided, and the flank face of the outer peripheral edge and the rake face of the outer peripheral edge of each outer peripheral edge have excellent machinability when formed by one curved surface. It has been found that chipping resistance can be obtained, and the present invention has been achieved.

  Furthermore, in this invention, the area | region of the front end side of an outer periphery blade is an area | region from the connection part of a bottom blade and an outer periphery blade to 30% of the blade diameter d, and the curvature radius R1 of the front-end | tip cutting edge part in the front end side of an outer periphery blade is 2 micrometers. More preferably, the radius of curvature R2 of the rear end cutting edge portion on the rear end side of the outer peripheral blade is 4 μm or less and is 1 μm or more and 3 μm or less. Thereby, chipping can be suppressed and more stable processing can be performed as the processing is performed under conditions such that the processing of the high hardness material and the cutting speed are increased by the square end mill.

  Further, in the present invention, the curvature radius Ra of the inner peripheral cutting edge portion forming from the tool axis to the position of 25% of the blade diameter among the bottom blades is 1 μm or more and 2 μm or less, and among the bottom blades, from the outer periphery. It is more desirable that the radius of curvature Rb of the outer peripheral cutting edge forming up to 25% of the blade diameter is 4 μm or more and 6 μm or less. As a result, when bottom cutting is performed with a square end mill, it is possible to improve chipping resistance and chip evacuation and to obtain a good surface finish.

  Furthermore, in the present invention, the one constituted by a blade portion having a plurality of bottom blades and outer peripheral blades, a shank portion having a diameter larger than that of the blade portion, and a neck portion connecting the blade portion and the shank portion is more effective. can get. This is because the blade portion is smaller in diameter than the shank portion, so that the deflection of the tool is likely to occur. Therefore, damage to the outer peripheral blade is likely to occur. Therefore, stable machining is difficult unless appropriate cutting edge ridge lines are applied to the front end side and the rear end side, respectively. By applying the knowledge of the outer peripheral edge and the bottom edge, it is possible to improve the chipping resistance and the chip discharge property, and to obtain a good machined surface quality.

  The curvature radius of the edge ridgeline in the outer peripheral edge and the bottom edge, which is a feature of the end mill of the present invention, can be formed by methods such as shot blasting, magnetic polishing, and barrel polishing. For example, FIG. 14 is a schematic view of a barrel polishing apparatus implemented in the present invention having a three-axis rotational axis. The barrel polishing apparatus 28 includes a first rotating means 29 for rotating the square end mill 1 around the tool central axis, a second rotating means 31 for rotating a holding station 30 holding the plurality of first rotating means 29, and polishing. It is comprised by the 3rd rotation means 33 which rotates main axis | shaft O 'of the barrel polishing apparatus with which the material 32 was inserted. They rotate in the cutting direction of the tool on all axes. The third rotating means 33 for rotating the main shaft O ′ of the barrel polishing apparatus is movable in a direction parallel to the rotation axis orthogonal to the rotation. That is, the position of the first rotating means 29 that directly holds the square end mill 1 can be made appropriate according to the magnitude of the movement of the abrasive. The reason why the rotary shaft is selected as the three-axis configuration is that the present invention needs to be able to change the polishing strength in all directions as much as possible in order to give different curvature radii depending on the positions of the edge edges of the outer peripheral edge and the bottom edge. It is. The behavior of the polishing medium in the barrel due to the flow of the polishing medium is complicated, and in the present invention, the third rotating means 33 for rotating the main shaft O ′ is movable in a direction parallel to the rotation axis orthogonal to the rotation. As a structure, the positions of the outer peripheral blade and the bottom blade that are in contact with the polishing medium can be controlled vertically.

  15 is a view of the barrel polishing apparatus shown in FIG. 14 when viewed from the lower side in FIG. In FIG. 15, the illustration of the square end mill is omitted. The first rotation means 29, the second rotation means 31, and the third rotation means 33 are respectively the rotation direction 34 of the first rotation means, the rotation direction 35 of the second rotation means, and the third rotation means. The rotation direction 36 can be rotated.

  The interaction between the abrasive 32 and the square end mill 1 generated by configuring the barrel polishing device 28 in this way will be described. When the cutting edge processing method by the barrel polishing apparatus is performed, relative movement occurs between the abrasive 32 and the square end mill 1, and the rake face of the square end mill 1 is in a direction perpendicular to the main axis O 'of the barrel polishing apparatus. Collide with. The abrasive 32 that has collided with the rake face 11 of the outer peripheral edge moves to the outside of the square end mill through the abrasive 32 passing through the groove of the square end mill while moving along the rake face 11 of the outer peripheral edge and the flank 10 of the outer peripheral edge. It is divided into abrasives 32. When the abrasive 32 moves, the surface along the moving direction is polished, so that the rake face 11 of the outer peripheral blade, the flank face 10 of the outer peripheral blade, and the edge ridge line 12 of the outer peripheral blade are polished. Therefore, a curved surface having a radius of curvature is formed in the front end cutting edge portion 19 and the rear end cutting edge portion 20 in the outer peripheral blade. Similarly, the abrasive 32 that has collided with the rake face 18 of the bottom blade moves under the rake face 18 of the bottom blade while passing through the groove of the square end mill and the bottom edge flank 16 and below the square end mill. It is divided into the abrasive 32 that moves to the side. Since the abrasive exhibits such behavior in the rotating barrel polishing apparatus, the rake face 18 of the bottom blade, the flank face 16 of the bottom blade, and the edge ridge line 17 of the bottom blade are polished. Therefore, a curved surface having a radius of curvature is formed on the inner peripheral cutting edge portion 22 and the outer peripheral cutting edge portion 23 of the bottom blade. Since the pressure of the abrasive 32 increases as the depth increases, the radius of curvature of the outer peripheral edge and the bottom edge formed by the abrasive 32 varies depending on the position in the depth direction. As a tendency, the radius of curvature of the outer peripheral blade is formed larger as it approaches the lower side of the square end mill, that is, the bottom blade. Further, in the blade edge processing method by the barrel polishing device 28, the grinding action to the square end mill works by the rotation of each rotating means, so that the radius of curvature of the bottom blade increases as it approaches the outer peripheral side of the square end mill, that is, the outer peripheral blade. The

  By constructing the drum-shaped polishing device 28 in this way, the polishing force is greater at the deepest position as the abrasive 32 approaches the bottom edge in the outer peripheral edge of the square end mill 1. Therefore, the radius of curvature R1 of the tip end cutting edge portion in the tip end cutting edge portion 19 is formed larger than the radius of curvature R2 of the rear end cutting edge portion in the rear end cutting edge portion 20. On the other hand, the outer peripheral blade is polished at a shallower position as it approaches the shank. Since the pressure of the abrasive 32 increases as the depth increases, the curvature closer to the R that forms the edge of the blade edge is provided closer to the bottom blade. Therefore, in the outer peripheral blade on the shank side, that is, the rear end cutting edge portion 20, the radius of curvature R2 that forms the edge of the cutting edge is formed small.

  Moreover, the curvature radius of the edge ridgeline of each site | part of an outer peripheral blade and a bottom blade can be adjusted with the setting of the rotating shaft in each rotating means. Specifically, the larger the number of revolutions of the main shaft O ′ of the barrel polishing apparatus in which the abrasive 32 is charged, the larger the radius of curvature R1 of the front end cutting edge and the radius of curvature R2 of the rear end cutting edge of the outer peripheral blade. This is because the polishing force near the outer periphery of the square end mill becomes stronger. In the case where the drum-like polishing device 28 by each rotating means is used, the polishing force in the portion near the outer periphery of the square end mill becomes strong. Therefore, in the bottom blade, the inner peripheral cutting edge portion of the inner peripheral cutting edge portion 22 The curvature radius Rb of the outer peripheral cutting edge portion in the outer peripheral cutting edge portion 23 is formed larger than the curvature radius Ra.

  Regarding the processing time, the longer the time, the larger the processing amount, that is, the longer the processing time, the larger the curvature radius of the cutting edge ridge line from the bottom edge to the outer peripheral edge. Since the abrasive flows in this manner, the square end mill 1 to which the cutting edge processing method using the barrel polishing apparatus 28 is applied has different curvature radii of the cutting edge ridgeline defined in the present invention depending on the location of the cutting edge. Can be. In the polishing method using the barrel treatment this time, the rotation shaft has a three-axis configuration and is variable in the depth direction of the barrel. Therefore, the rotational speed, rotational direction, processing depth, etc. of each axis can be changed.

  In the blade edge processing method using a drum-shaped polishing machine having a three-axis rotating shaft according to the present invention, an abrasive including a resin-based elastic material is used. Examples of the resin-based elastic material suitable for the blade edge processing method of the present invention include walnuts, coconuts, and cones having a particle size of 0.1 mm or more and less than 3 mm. By applying diamond powder with a particle size of 0.1 μm or more and 0.5 μm or less to the abrasive by applying these resin-based elastic materials to the abrasive, and performing the blade edge treatment, the square end mill can be cut according to the location of the cutting edge. The shape can have different curvature radii. The resin-based elastic material and the abrasive can be selected depending on the shape of the square end mill, the desired radius of curvature of the cutting edge portion, and the like.

  The first rotation means 29, the second rotation means 31, and the third rotation means 33 in the barrel polishing apparatus 28 can independently set the rotation speed and the rotation direction. By appropriately selecting these conditions, it is possible to change the method of changing the curvature radius of the edge of the cutting edge depending on the location of the cutting edge.

  The present invention can be applied to square end mills and long neck square end mills of various shapes. In particular, a square end mill in which the value of the blade diameter d is equal to the value of the shank diameter D, or the blade diameter d is the shank diameter. By carrying out a long neck square end mill smaller than D, the advantageous effects of the present invention can be exhibited. Further, it is more effective to implement for a square end mill and a long neck square end mill having 2 to 6 blades and a blade diameter d of 0.1 mm to 25 mm. A particularly desirable blade diameter d is in the range of 4 mm to 20 mm.

  Further, the curvature radius R1 of the leading edge cutting edge, the curvature radius R2 of the trailing edge cutting edge, the curvature radius Ra of the inner circumferential cutting edge, and the curvature radius Rb of the outer circumferential cutting edge, which are important elements in the present invention, are known. It is possible to obtain by this measurement method. If a specific example is given regarding the measuring method of the curvature radius R1 of the leading edge and the curvature radius R2 of the trailing edge, the square end mill and the long neck square end mill of the present invention are cut in a direction perpendicular to the tool axis O. Then, a measurement sample having a thickness of about 1 mm is prepared, and the shape of the leading edge portion 19 and the trailing edge portion 20 is measured using a method of measuring the measurement sample using an optical microscope or a contact-type shape measuring instrument. There is a method of measuring from the shape of the traced leading edge 19 and trailing edge 20. Similarly, if a specific example is given regarding the measuring method of the curvature radius Ra of the inner peripheral cutting edge portion and the curvature radius Rb of the outer peripheral cutting edge portion, the square end mill and the long neck square end mill of the present invention are passed through the bottom blade. In addition, the sample is cut in a direction parallel to the tool axis O, a measurement sample having a thickness of about 0.3 mm is prepared, and a measurement sample is measured using an optical microscope, or a contact type shape measuring instrument is used. There is a method in which the shapes of the inner peripheral cutting edge portion 22 and the outer peripheral cutting edge portion 23 are traced and measurement is performed from the traced shapes of the inner peripheral cutting edge portion 22 and the outer peripheral cutting edge portion 23.

  Hereinafter, the present invention will be described in detail by the following examples, but the present invention is not limited thereto.

Example 1
Both the present invention example and the conventional example, the long neck square end mill has a blade diameter d of 1 mm, a neck diameter of 0.96 mm, a blade length of 1.5 mm, and a neck length that combines the blade part and the neck part. A WC-based cemented carbide base material having a length of 6 mm and a shank diameter D of 4 mm is coated with 4 μm of a hard coating of AlCrSiN.

  As Example 1 of the present invention, the radius of curvature R1 of the tip cutting edge is 3 μm, the radius of curvature R2 of the trailing edge is 2 μm, and the length of the tip side of the outer peripheral blade, that is, the length of the tip cutting edge is It is 0.3 mm (30% of the blade diameter d) from the joint part of the blade. Furthermore, the curvature radius Ra of the inner peripheral cutting edge portion in the bottom blade was 1.5 μm, and the curvature radius Rb of the outer peripheral cutting edge portion was 5.0 μm.

  Conventional Example 1 is an application of the invention described in Patent Document 2 to a long neck square end mill, wherein the radius of curvature R1 of the leading edge is 4 μm and the radius of curvature R2 of the trailing edge is 7 μm. The region on the tip side of the blade, that is, the length of the tip cutting edge portion is 0.5 mm (about 50% of the blade diameter) from the connecting portion of the bottom blade and the outer peripheral blade. Further, in the bottom blade, the curvature radius Ra of the inner peripheral cutting edge portion is 2.0 μm, and the curvature radius Rb of the outer peripheral cutting edge portion is 2.5 μm. That is, the curvature radius R2 of the rear end cutting edge portion on the rear end side of the outer peripheral blade is particularly increased.

FIG. 13 is an enlarged view of the vicinity of the connecting portion between the bottom blade and the outer peripheral blade in Conventional Example 2. Conventional Example 2 applies the invention described in Patent Document 1 to a long neck square end mill, and the end mill 24 of Conventional Example 2 has a rear end side from the front end side of the outer peripheral blade 3 as shown in FIG. The radius of curvature of the ridgeline of the outer peripheral blade is gradually reduced through to. Therefore, there is no boundary between the front end side of the outer peripheral blade and the rear end side of the outer peripheral blade in the present invention, and the length of the front end cutting edge portion is not measured.
Note that the radius of curvature of the edge of the cutting edge at a position away from the connecting portion between the bottom blade 2 and the outer peripheral blade 3 in the direction of the tool axis O by 20% of the blade diameter d is 7 μm (in Table 1 described later, (It is described in the column of the curvature radius R1 of the blade portion). Further, the radius of curvature of the edge of the blade edge at a position away from the connecting portion of the bottom blade 2 and the outer peripheral blade 3 in the direction of the tool axis O by 60% of the blade diameter d is 5 μm (in Table 1 described later, (It is described in the column of curvature radius R2 of the blade portion). Further, in the bottom blade, the radius of curvature Ra of the inner peripheral cutting edge is 2 μm, and the radius of curvature Rb of the outer peripheral cutting edge is 2.5 μm.

Conventional Example 3 applies the invention described in Patent Document 3 to a long neck square end mill. The end mill of Conventional Example 3 has a radius of curvature of the ridgeline of the outer peripheral blade from the front end side to the rear end side of the outer peripheral blade. It is the same thing. Therefore, there is no boundary between the front end side of the outer peripheral blade and the rear end side of the outer peripheral blade in the present invention, and the length of the front end cutting edge portion is not measured.
Note that the radius of curvature of the edge of the cutting edge at a position away from the joint between the bottom blade 2 and the outer peripheral blade 3 in the direction of the tool axis O by 20% of the blade diameter d is 5 μm (in Table 1 described later, (It is described in the column of the curvature radius R1 of the blade portion). Further, the radius of curvature of the edge of the blade edge at a position away from the connecting portion of the bottom blade 2 and the outer peripheral blade 3 in the direction of the tool axis O by 60% of the blade diameter d is 5 μm (in Table 1 described later, (It is described in the column of curvature radius R2 of the blade portion). Further, in the bottom blade, the radius of curvature Ra of the inner peripheral cutting edge is 2 μm, and the radius of curvature Rb of the outer peripheral cutting edge is 2.5 μm.

  All of the tools produced as Invention Example 1 and Conventional Examples 1 to 3 are two-blade long neck square end mills based on the same cemented carbide, and in the tool specifications other than the curvature radius of the cutting edge. A comparative test was conducted in a unified state. The cutting test was wet cutting using a water-soluble cutting fluid, and a 52HRC plastic mold material (trade name: HPM38, manufactured by Hitachi Metals, Ltd.) was used as the work material. A rib groove shape having an amount of 0.1 mm, a rotation speed of 15,000 rotations / min, a feed rate of 450 mm / min, a width of 1.5 mm, a depth of 6 mm, and a groove length of 20 mm was cut.

  As evaluation methods, the finished surface roughness of the machined surface after cutting and the flank wear width of the tool were used. The finished surface roughness Rz was measured in the axial direction of the processed surface, and evaluated with the maximum height roughness Rz. The flank wear width of the tool is measured with an optical microscope for the flank wear width of the outer peripheral blade at two locations on the tip side of the outer peripheral blade and the rear end side of the outer peripheral blade. did. As evaluation criteria, a finished surface roughness Rz of 1.0 μm or less and a flank wear width of 0.02 mm or less at both locations were considered good. The evaluation results are shown in Table 1.

  From the cutting evaluation results, Example 1 of the present invention showed a satisfactory result because the finished surface roughness Rz was 0.7 μm and the flank wear width was 0.02 mm or less at both locations. This is because the curvature radius of the intersection of the flank and the rake face is made smaller than the curvature radius R1 of the leading edge cutting edge than the curvature radius R1 of the leading edge cutting edge, so that chipping due to chatter vibration can be suppressed on the entire outer peripheral edge. This is because. In addition, since the outer peripheral rear end portion was more machinable than the front end side, there was no peeling on the processed surface, and a good processed surface was obtained.

  On the other hand, in all of the conventional examples 1 to 3, since chipping was caused by the outer peripheral blade, the finished surface roughness exceeded 1.0 μm, and the flank wear width exceeded 0.03 mm at both locations, which was defective. In Conventional Example 1, since the radius of curvature R2 of the rear end cutting edge portion was particularly large as 7 μm, chatter vibration due to slight vibration occurred and chipping was likely to occur. In Conventional Example 2, the radius of curvature R1 of the tip cutting edge is as large as 7 μm, and the curvature radius of the ridgeline of the outer peripheral blade is gradually reduced from the front end side to the rear end side of the outer peripheral blade. The biting into the lips was poor and eventually chipping occurred. In Conventional Example 3, chipping occurred intermittently from the front end to the rear end side of the outer peripheral blade. This is because the radius of curvature of the edge ridgeline of the outer peripheral blade is constant, and the reason is that it is particularly affected by the deflection generated during cutting.

(Example 2)
As examples of the present invention and conventional examples, the same tools as those used in Example 1 were used for evaluation. The cutting test is wet cutting using a water-soluble cutting fluid, and a 52HRC plastic mold material (trade name: HPM38, manufactured by Hitachi Metals, Ltd.) is used as the work material. A rib groove shape similar to that in Example 1 was cut at an amount of 0.03 mm, a rotation speed of 15,000 rotations / min, and a feed rate of 450 mm / min.

  As an evaluation method, after finishing the rib groove shape one by one using five of the same tools, the finished surface roughness of the machined surface is measured, and the best finished surface roughness Rz and the worst finished surface roughness are measured. Evaluation was performed by measuring the difference in the finished surface roughness Rz, which is the difference in Rz. As an evaluation standard, a case where the difference in the finished surface roughness Rz was 0.2 μm or less was regarded as good. The evaluation results are shown in Table 2.

  From the cutting evaluation results, the present invention example 1 was evaluated as five, and as a result, a processed surface having a finished surface roughness Rz of 0.6 μm to 0.8 μm was obtained. Therefore, the difference in the finished surface roughness Rz was 0.2 μm, indicating a good result. This is because the radius of curvature R1 of the leading edge is larger than the radius of curvature R2 of the trailing edge, and the cutting edge ridge line is optimized by the area of the outer edge, so that chipping suppression near the leading edge involved in cutting is suppressed. This is because stable cutting without chatter vibration has become possible.

  On the other hand, all of the conventional examples 1 to 3 have large variations in the finished surface roughness Rz of the processed surface, and even when looking at the difference in the finished surface roughness Rz, a variation of 0.4 μm to 0.5 μm was confirmed, there were. In Conventional Example 1, since the radius of curvature R2 of the rear edge cutting edge is as large as 7 μm, chipping on the rear edge side of the outer peripheral edge caused by chatter vibration causes the machining surface to be roughened. In Conventional Example 2, the radius of curvature of the tip cutting edge portion is as large as 7 μm, and the curvature radius of the ridgeline of the outer peripheral blade is gradually reduced from the front end side to the rear end side of the outer peripheral blade. The bitterness was bad and chatter vibration occurred. In addition, chipping occurred on the rear end side of the outer peripheral blade, thereby roughening the processed surface. In Conventional Example 3, chipping occurred intermittently from the front end to the rear end side. This is because the radius of curvature of the edge edge of the outer peripheral blade is constant. In addition, the degree of chipping was severer on the rear end side because it was particularly affected by the deflection generated during cutting, which affected the machined surface roughness. In addition, although the surface roughness has deteriorated due to chipping, the timing at which chipping occurs varies, and the size of the chipping actually differs from test to test even with the same specification tool. Become a thing. Therefore, the quality of the processed surface varies.

(Example 3)
Each of the long neck square end mills of the present invention has a blade diameter d of 3 mm, a neck diameter of 2.88 mm, a blade length of 4.5 mm, and a neck length of 16 mm which is the combined length of the blade and the neck. A WC-based cemented carbide base material having a shank diameter D of 6 mm is coated with 4 μm of a hard coating of AlCrSiN.

  For inventive examples 1 to 3, the radius of curvature R1 of the leading edge is 3 μm, the radius of curvature R2 of the trailing edge is 2 μm, the radius of curvature Ra of the inner peripheral edge is 1.5 μm, and the curvature of the outer peripheral edge is The radius Rb was set to 5.0 μm and the specifications were unified.

  Furthermore, as Example 1 of the present invention, the length of the distal end side region of the outer peripheral blade, that is, the length of the distal cutting edge portion was set to 0.90 mm (30% of the blade diameter d) from the connecting portion of the bottom blade and the outer peripheral blade. Further, as Example 2 of the present invention, the length of the tip cutting edge portion was 0.60 mm (20% of the blade diameter d) from the connecting portion of the bottom blade and the outer peripheral blade. Furthermore, as Example 3 of the present invention, the length of the tip cutting edge portion was 1.05 mm (35% of the blade diameter d) from the connecting portion of the bottom blade and the outer peripheral blade.

  For comparison, Conventional Example 4 (the same base material material and hard coating specifications as the above-described example of the present invention) was added. In Conventional Example 4, the radius of curvature R1 of the leading edge is 5 μm, the radius of curvature R2 of the trailing edge is 8 μm, and the length of the distal edge of the outer peripheral blade, that is, the length of the distal cutting edge, is the bottom blade and the outer peripheral blade. This is a region of 1.50 mm (50% of the blade diameter d) from the connecting portion. Further, in the bottom blade, the curvature radius Ra of the inner peripheral cutting edge portion is 2.0 μm, and the curvature radius Rb of the outer peripheral cutting edge portion is 2.5 μm.

  The cutting test is wet cutting using a water-soluble cutting fluid, and a 40HRC plastic mold material (trade name: HPM-MAGIC (registered trademark), manufactured by Hitachi Metals, Ltd.) is used as the work material. Side cutting was carried out at a rate of .8 mm, a cutting amount in the pick direction of 0.1 mm, a rotation speed of 8,000 rotations / min, and a feed rate of 500 mm / min. Machining was performed 20 times with an axial depth of cut of 0.8 mm, and the final machining depth was up to 16 mm.

  As an evaluation method, the finished surface roughness Rz of the machined surface after cutting was measured. The finished surface roughness of the machined surface was measured in the axial direction of the machined surface and evaluated with the maximum height roughness Rz. As an evaluation standard, the case where the finished surface roughness Rz was 1.5 μm or less was considered good. The evaluation results are shown in Table 3.

  From the cutting evaluation results, Examples 1 to 3 of the present invention were all good because the finished surface was finished with a finished surface roughness Rz of 1.5 μm or less. In particular, Examples 1 and 2 of the present invention in which the length of the cutting edge of the tip is from the connecting portion of the bottom blade and the outer peripheral blade to 30% of the blade diameter realizes Rz of 1.2 μm or less, and very good results (Table 3 in the evaluation column in 3. This is the effect of optimizing the ridge line on the front end side of the outer peripheral blade that is involved in cutting and is the most loaded, and is because it can be stably processed to the end without chipping.

  On the other hand, in the conventional example 4, the finished surface roughness Rz was 1.9 μm, which was the worst value and was poor (× in the evaluation column in Table 3). This is because the cutting edge ridge line is not optimized and chipping occurs on the tip side of the outer peripheral blade, and the machining surface is deteriorated due to the influence, and the curvature radius R2 of the trailing edge cutting edge is the curvature of the leading edge cutting edge. Since it is larger than the radius R1, it can be assumed that when the outer peripheral edge rubs the processed surface due to the deflection of the tool, the resistance increases and the processed surface is deteriorated.

Example 4
All of the long neck square end mills of the present invention have a WC base with a blade diameter d of 3 mm, a neck diameter of 2.88 mm, a blade length of 4.5 mm, a neck length of 16 mm, and a shank diameter D of 6 mm. All of them are obtained by coating a hard film of AlCrSiN with a thickness of 4 μm on a hard alloy substrate.

  For each of Examples 4 to 13, the length of the tip cutting edge is 0.90 mm (30% of the blade diameter d) from the joint between the bottom cutting edge and the outer cutting edge, and the inner cutting edge of the bottom cutting edge The curvature radius Ra was 1.5 μm, the curvature radius Rb of the outer peripheral cutting edge was 5.0 μm, and the specifications were unified. Regarding this example, the curvature radius of the edge edge line of the outer peripheral edge was changed, and the tendency of the cutting performance due to this was confirmed.

First, the radius of curvature R1 of the tip cutting edge was examined. In Invention Example 4, the radius of curvature R1 of the front end cutting edge was 1.5 μm and the radius of curvature R2 of the rear end cutting edge was 1.0 μm.
As Example 5 of the present invention, the radius of curvature R1 of the front end cutting edge was 2.0 μm, and the radius of curvature R2 of the rear end cutting edge was 1.0 μm.
As Example 6 of the present invention, the curvature radius R1 of the leading edge part was 3.0 μm, and the curvature radius R2 of the trailing edge part was 1.0 μm.
As Example 7 of the present invention, the curvature radius R1 of the leading edge part was 4.0 μm, and the curvature radius R2 of the trailing edge part was 1.0 μm.
As Example 8 of the present invention, the radius of curvature R1 of the leading edge portion was 5.0 μm, and the radius of curvature R2 of the trailing edge portion was 1.0 μm.

Next, the radius of curvature R2 of the rear edge cutting edge was examined. As Example 9 of the present invention, the radius of curvature R1 of the tip cutting edge was 4.0 μm, and the radius of curvature R2 of the ridge line on the rear end side of the outer peripheral blade was 0.5 μm.
As Example 10 of the present invention, the curvature radius R1 of the leading edge part was 4.0 μm, and the curvature radius R2 of the trailing edge part was 1.0 μm.
As Example 11 of the present invention, the radius of curvature R1 of the leading edge portion was 4.0 μm, and the radius of curvature R2 of the trailing edge portion was 2.0 μm.
As Invention Example 12, the radius of curvature R1 of the front end cutting edge was 4.0 μm, and the radius of curvature R2 of the rear end cutting edge was 3.0 μm.
As Example 13 of the present invention, the curvature radius R1 of the leading edge part was 4.0 μm, and the curvature radius R2 of the trailing edge part was 3.5 μm. As a comparison, the same Conventional Example 4 as that used in Example 3 was added.

  The cutting test was performed by wet cutting using a water-soluble cutting fluid, and a 40HRC plastic mold material (trade name: HPM-MAGIC (registered trademark, manufactured by Hitachi Metals, Ltd.) was used as the work material. Side cutting was performed at 8mm, pick direction cut amount 0.1mm, rotation speed 8,000 rotations / min, feed rate 500mm / min. The depth was up to 16 mm.

  As an evaluation method, flank wear widths of tools after cutting were compared. The surface was cut to a certain distance (30 m) by side cutting, and the wear width at that time was measured and evaluated. As an evaluation standard, the case where the flank wear width was 0.08 mm or less was considered good. The evaluation results are shown in Table 4.

From the cutting evaluation results, all of the inventive examples 4 to 13 had a wear width of 0.08 mm or less, and were good results. Among them, Examples 5 to 7 of the present invention in which the radius of curvature R1 of the cutting edge of the tip is 2 μm or more and 4 μm or less have a flank wear width of 0.05 mm or less, and particularly good results (に お け る in the evaluation column in Table 4). )Met. This is an effect that combines the cutting edge strength capable of realizing chipping resistance while ensuring the biting property of the cutting edge ridge line on the tip side of the outer peripheral blade.
In the inventive examples 10 to 12 where the radius of curvature R2 of the rear edge cutting edge portion is 1 μm or more and 3 μm or less, the flank wear width is 0.05 mm or less, and particularly good results (（in the evaluation column in Table 4). there were. This is an effect of optimizing the edge edge line on the rear end side of the outer peripheral blade. Since the rear end side of the outer peripheral blade is not directly involved in the cutting, it is only necessary to have a blade edge strength that does not vibrate and does not chip with respect to contact with the machining surface when a slight deflection of the tool occurs. With respect to Invention Examples 10 to 12, since they were satisfied, the wear width was small and stable.

  On the other hand, in Conventional Example 4, the flank wear width is 0.09 mm, which is the worst value. This is because the edge of the edge of the blade is not optimized, the biting on the tip side of the outer peripheral blade is poor, chipping occurs, and vibration occurs. It is thought that the effect also appeared on the rear end side of the outer peripheral blade and led to a large wear width.

(Example 5)
Examples of the present invention are all long neck square end mills, WC-based cemented carbide with a blade diameter d of 1 mm, a neck diameter of 0.96 mm, a blade length of 1.5 mm, a neck length of 4 mm, and a shank diameter of 4 mm. All of the hard substrates of AlCrSiN were coated with 4 μm on the base material.

  In each of Examples 14 to 23, the length of the tip cutting edge portion is 0.3 mm (30% of the blade diameter d) from the connecting portion between the bottom blade and the outer peripheral blade, and the curvature radius R1 of the tip cutting edge portion is 3 μm. The blade edge ridgeline R2 of the rear edge cutting edge portion was 2 μm, and the specifications were unified. Regarding this example, the curvature radius of the bottom blade was changed, and the tendency of the cutting performance was confirmed.

First, the radius of curvature Ra of the inner peripheral cutting edge was examined. In Invention Example 14, the radius of curvature Ra of the inner peripheral cutting edge was 0.5 μm, and the radius of curvature Rb of the outer peripheral cutting edge was 5.0 μm.
In Invention Example 15, the radius of curvature Ra of the inner peripheral cutting edge was 1.0 μm, and the radius of curvature Rb of the outer peripheral cutting edge was 5.0 μm.
In Invention Example 16, the radius of curvature Ra of the inner peripheral cutting edge was 1.5 μm, and the radius of curvature Rb of the outer peripheral cutting edge was 5.0 μm.
As Example 17 of the present invention, the curvature radius Ra of the inner peripheral cutting edge was 2.0 μm, and the curvature radius Rb of the outer peripheral cutting edge was 5.0 μm.
As Example 18 of the present invention, the curvature radius Ra of the inner peripheral cutting edge was 2.5 μm, and the curvature radius Rb of the outer peripheral cutting edge was 5.0 μm.

Next, the radius of curvature Rb of the outer peripheral cutting edge was examined. In Invention Example 19, the radius of curvature Ra of the inner peripheral cutting edge was 1.5 μm, and the radius of curvature Rb of the outer peripheral cutting edge was 3.0 μm.
In Invention Example 20, the radius of curvature Ra of the inner peripheral cutting edge was 1.5 μm, and the radius of curvature Rb of the outer peripheral cutting edge was 4.0 μm.
As Invention Example 21, the radius of curvature Ra of the inner peripheral cutting edge was 1.5 μm, and the radius of curvature Rb of the outer peripheral cutting edge was 5.0 μm.
As Example 22 of the present invention, the radius of curvature Ra of the inner peripheral cutting edge was 1.5 μm, and the radius of curvature Rb of the outer peripheral cutting edge was 6.0 μm.
As Inventive Example 23, the curvature radius Ra of the inner peripheral cutting edge was 1.5 μm, and the curvature radius Rb of the outer peripheral cutting edge was 7.0 μm.

  As a comparison, Conventional Example 5 (the same base material material and hard coating specifications as in the above-described example of the present invention) was added. In Conventional Example 5, the radius of curvature R1 of the leading edge is 4 μm, the radius of curvature R2 of the trailing edge is 7 μm, and the length of the leading edge is 0.5 mm from the joint between the bottom edge and the outer edge ( 50% of the blade diameter d). Furthermore, the curvature radius Ra of the inner peripheral cutting edge in the bottom blade is 2 μm, and the curvature radius Rb of the outer peripheral cutting edge is 2.5 μm.

  The cutting test is wet cutting using a water-soluble cutting fluid, and a 52HRC plastic mold material (trade name: HPM38, manufactured by Hitachi Metals, Ltd.) is used as the work material. Bottom cutting was performed at an amount of 0.03 mm, a rotation speed of 15,000 rotations / min, and a feed rate of 450 mm / min. The machining distance was 8 m per piece. Further, the same cutting was performed for five tools.

  As an evaluation method, after machining using five of the same tools, the finished surface roughness of the machined surface is measured, and the finish is the difference between the best finished surface roughness Rz and the worst finished surface roughness Rz. Evaluation was performed by measuring the difference in surface roughness Rz. As an evaluation criterion, a case where the difference in the finished surface roughness Rz was 0.4 μm or less was regarded as good. The evaluation results are shown in Table 5.

  From the results of the cutting evaluation, Examples 14 to 23 of the present invention were all good because the difference in the finished surface roughness Rz was 0.4 μm or less. In particular, Examples 15 to 17 of the invention examples 15 to 17 in which the radius of curvature Ra of the inner peripheral cutting edge portion was 1 μm or more and 2 μm or less were very good because the difference in the finished surface roughness Rz was 0.2 μm or less. This is an effect that the curvature radius Ra of the inner peripheral cutting edge can be optimized. By setting the radius of curvature Ra of the inner peripheral cutting edge to 1 μm or more and 2 μm or less, the cutting edge has a strength sufficient to withstand chipping caused by minute vibrations when cutting with the bottom blade, and the cutting resistance is also increased. Absent. It can be presumed that this is the reason why a good processed surface can be formed.

  Also, in the inventive examples 20 to 22 in which the radius of curvature Rb of the outer peripheral cutting edge portion is 4 μm or more and 6 μm or less, the difference in the finished surface roughness Rz was 0.2 μm or less, which was very good. This is an effect that the radius of curvature Rb of the outer peripheral cutting edge portion can be optimized. By setting the radius of curvature Rb of the outer peripheral cutting edge to 4 μm or more and 6 μm or less, it can be said that both the edge strength and the machinability of the portion related to cutting at the portion close to the outer peripheral blade can be secured. Since it has good machinability and can be processed without chipping, it is possible to obtain a good finished surface with a stable roughness. In particular, in the case of cutting of a tool such as the present invention example in which the length under the neck exists, it is easy to be affected by slight vibration, so the optimization of the value of the radius of curvature Rb of the outer peripheral cutting edge improves the cutting performance. The impact on is great.

  Further, in Conventional Example 5, the difference in the finished surface roughness Rz was 0.5 μm after processing five. This is because the radius of curvature Rb of the outer peripheral cutting edge portion is as small as 2.5 μm, and even a slight vibration causes chipping because the portion near the corner portion has insufficient blade edge strength. Even if a slight chipping occurs, this affects the machined surface.

(Example 6)
The shape of the square end mill in the present example is the shape shown in FIG. 1, on a WC-based cemented carbide substrate having a blade diameter d of 6 mm, a blade length of 13 mm, a total length of 60 mm, and a shank diameter D of 6 mm. Further, a hard coating of AlCrSiN was coated with 4 μm. The length of the tip cutting edge portion was 1.8 mm (30% of the blade diameter d) from the connecting portion between the bottom blade and the outer peripheral blade. Regarding the outer peripheral edge, the radius of curvature R1 of the front end cutting edge was 3 μm, and the radius of curvature R2 of the rear end cutting edge was 2 μm. Regarding the bottom blade, the curvature radius Ra of the inner peripheral cutting edge portion was 1.5 μm, and the curvature radius Rb of the outer peripheral cutting edge portion was 5.0 μm.

  The square end mill of the conventional example to be compared is coated with a 4 μm hard coating of AlCrSiN on a WC-based cemented carbide base material having a blade diameter d of 6 mm, a blade length of 13 mm, a total length of 60 mm, and a shank diameter D of 6 mm. It is a thing. The length of the tip cutting edge portion was 3.0 mm (50% of the blade diameter d) from the connecting portion between the bottom blade and the outer peripheral blade. Regarding the outer peripheral edge, the radius of curvature R1 of the leading edge edge was 5 μm, and the radius of curvature R2 of the rear edge edge was 5 μm. Regarding the bottom blade, the curvature radius Ra of the inner peripheral cutting edge portion was 2.0 μm, and the curvature radius Rb of the outer peripheral cutting edge portion was 2.5 μm.

  The cutting test was wet cutting using a water-soluble cutting fluid, 220HB carbon steel S50C was used as the work material, the axial cut amount was 9.0 mm, the pick direction cut amount was 0.6 mm, and the rotational speed was 6,400 rpm. Side cutting was performed at a feed rate of 1,870 mm / min. The machining distance was 30 m per piece.

  As an evaluation method, the finished surface roughness Rz of the processed surface was evaluated. As an evaluation standard, a finished surface roughness Rz of 1.0 μm or less was considered good. The evaluation results are shown in Table 6.

  From the results of the cutting evaluation, since no chipping was observed in the entire region of the outer peripheral edge, Example 24 of the present invention had a finished surface roughness Rz of 1.0 μm or less and showed a good result. This is because the radius of curvature of the intersection of the flank and the rake face is increased by the radius of curvature R1 on the outer peripheral tip side, so that chipping due to chatter vibration can be suppressed over the entire outer peripheral blade. In addition, since the outer peripheral rear end portion is more machinable than the front end side, the processed surface is not peeled off and a good processed surface can be obtained.

  On the other hand, in the conventional example 6, since chipping was caused by the outer peripheral blade, the finished surface roughness Rz was 1.5 μm or less, which was defective. In Conventional Example 6, since the radius of curvature of the edge edge of the outer peripheral blade is constant, chatter vibration is amplified even by slight vibration, and chipping tends to occur on the rear end side of the outer peripheral blade. As a result, the machined surface is affected and the surface roughness is deteriorated.

(Example 7)
The shape of the square end mill in the present embodiment is the shape shown in FIG. 1 and is a top of a WC-based cemented carbide substrate having a blade diameter d of 10 mm, a blade length of 22 mm, a total length of 80 mm, and a shank diameter D of 10 mm. Further, a hard coating of AlCrSiN was coated with 4 μm.

  In each of the inventive examples 25 to 34, the length of the tip cutting edge portion is 3.0 mm (30% of the blade diameter d) from the connecting portion of the bottom cutting edge and the outer cutting edge, and the inner cutting edge portion in the bottom cutting edge. The curvature radius Ra was 1.5 μm, the curvature radius Rb of the outer peripheral cutting edge was 5.0 μm, and the specifications were unified. Regarding this example, the curvature radius of the edge edge line of the outer peripheral edge was changed, and the tendency of the cutting performance due to this was confirmed.

First, the radius of curvature R1 of the tip cutting edge was examined. In Invention Example 25, the radius of curvature R1 of the tip end cutting edge was 1.5 μm, and the radius of curvature R2 of the rear end cutting edge was 1.0 μm.
As Example 26 of the present invention, the radius of curvature R1 of the leading edge portion was 2.0 μm, and the radius of curvature R2 of the trailing edge portion was 1.0 μm.
As Example 27 of the present invention, the curvature radius R1 of the leading edge part was 3.0 μm, and the curvature radius R2 of the trailing edge part was 1.0 μm.
As Example 28 of the present invention, the radius of curvature R1 of the leading edge portion was 4.0 μm, and the radius of curvature R2 of the trailing edge portion was 1.0 μm.
As Example 29 of the present invention, the radius of curvature R1 of the leading edge portion was 5.0 μm, and the radius of curvature R2 of the trailing edge portion was 1.0 μm.

Next, the radius of curvature R2 of the rear edge cutting edge was examined. As Example 30 of the present invention, the radius of curvature R1 of the tip cutting edge was 4.0 μm, and the radius of curvature R2 of the ridge line on the rear end side of the outer peripheral blade was 0.5 μm.
As Example 31 of the present invention, the radius of curvature R1 of the front end cutting edge was 4.0 μm, and the radius of curvature R2 of the rear end cutting edge was 1.0 μm.
As Example 32 of the present invention, the radius of curvature R1 of the leading edge portion was 4.0 μm, and the radius of curvature R2 of the trailing edge portion was 2.0 μm.
As Example 33 of the present invention, the radius of curvature R1 of the leading edge portion was 4.0 μm, and the radius of curvature R2 of the trailing edge portion was 3.0 μm.
As Example 34 of the present invention, the radius of curvature R1 of the leading edge portion was 4.0 μm, and the radius of curvature R2 of the trailing edge portion was 3.5 μm.

  The square end mill of the conventional example to be compared is coated with a 4 μm hard coating of AlCrSiN on a WC-based cemented carbide base material having a blade diameter d of 10 mm, a blade length of 22 mm, a total length of 80 mm, and a shank diameter D of 10 mm. It is a thing. The length of the tip cutting edge portion was 5.0 mm (50% of the blade diameter d) from the connecting portion between the bottom blade and the outer peripheral blade. Regarding the outer peripheral edge, the radius of curvature R1 of the leading edge edge was 5 μm, and the radius of curvature R2 of the rear edge edge was 5 μm. Regarding the bottom blade, the curvature radius Ra of the inner peripheral cutting edge portion was 2.0 μm, and the curvature radius Rb of the outer peripheral cutting edge portion was 2.5 μm.

  The cutting test was wet cutting using a water-soluble cutting fluid, 220HB carbon steel S50C was used as the work material, the axial cut amount was 15.0 mm, the pick direction cut amount was 1.0 mm, and the rotational speed was 3,820 rpm. Side cutting was performed at a feed rate of 1,160 mm / min. The machining distance was 20 m per piece. Since the cutting depth in the axial direction is 15.0 mm, in the cutting test, the leading edge portion and the trailing edge portion simultaneously contribute to the cutting process.

  As an evaluation method, the finished surface roughness Rz of the processed surface was evaluated. As an evaluation standard, a finished surface roughness Rz of 1.5 μm or less was considered good. Table 7 shows the evaluation results.

  From the cutting evaluation results, the inventive examples 25 to 34 all had a finished surface roughness Rz of 1.5 μm or less, and were good results. In particular, the inventive examples 26 to 28 in which the radius of curvature R1 of the tip cutting edge part is 2 μm or more and 4 μm or less were very good with the finished surface roughness Rz of 1.2 μm or less. This is an effect that the curvature radius R1 of the tip cutting edge portion can be optimized. By setting the radius of curvature R1 of the cutting edge of the tip to 2 μm or more and 4 μm or less, it is possible to have a cutting edge strength that is not affected by chatter vibration when chipping on the tip side of the outer peripheral blade and is less likely to cause chipping. I can guess that.

  Also, in the inventive examples 31 to 33 in which the radius of curvature R2 of the tip cutting edge portion is 1 μm or more and 3 μm or less, the finished surface roughness Rz is 1.2 μm or less, which is very good. This is an effect that the curvature radius R2 of the tip cutting edge portion can be optimized. By setting the radius of curvature R2 of the outer peripheral cutting edge to 1 μm or more and 3 μm or less, it can be said that both the edge strength and the machinability of the portion related to cutting at the portion near the rear end side of the outer peripheral blade can be secured. Since it has good machinability and can be processed without chipping, it is possible to obtain a good finished surface with a stable roughness.

  In Conventional Example 7, the finished surface roughness Rz was 1.8 μm. This is because the radius of curvature R1 and R2 of the cutting edge of the tip is 5 μm, which is the same value, so that the edge strength is insufficient on the tip side of the outer edge where chatter vibration is likely to occur, and on the rear end side of the outer edge. Because of lack of machinability, it is affected by chatter vibration. As a result, the cutting edge of the tip causes chipping and vibration is generated on the rear end side, so that the processed surface is also affected.

In the said Example, although the case where the base material made from a WC group cemented carbide was used was described, it is not specifically limited. For example, the advantageous effects of the present invention can also be achieved when high-speed steel, cubic boron nitride (cBN), tool steel, cermet, ceramics, or the like is used as the base material.
Moreover, in the said Example, although the case where AlCrSiN was coat | covered as a hard film was described, it does not specifically limit. For example, even when AlCrN, AlCrNC, AlCrNCB, AlCrSiNC, AlCrSiNCB, TiAlN, TiAlNC, TiAlNCB, CrSiN, CrSiNC, CrSiNCB, TiCN, TiC, or TiCNB are used as the hard coating, the effects of the present invention can be achieved.

  According to the present invention, even in side cutting when the axial cut is large with a long protrusion amount, occurrence of chipping in the entire outer peripheral blade can be suppressed, and stable cutting can be performed without chatter vibration. . In particular, in a long neck square end mill in which the blade diameter d is smaller than the shank diameter D, chipping of the blade portion can be suppressed, which is particularly effective for deep engraving.

DESCRIPTION OF SYMBOLS 1 Square end mill 2 Bottom blade 3 Outer peripheral blade 4 Shank part 5 Long neck square end mill 6 Blade part 8 Neck part 10 Flank face of outer peripheral edge 11 Rake face of outer peripheral edge 12 Edge edge line of outer peripheral edge 13 Flank face of outer peripheral edge in the conventional end mill 14 Rake face of outer peripheral edge in conventional end mill 15 Edge edge line of outer peripheral edge in conventional end mill 16 Flank face of bottom edge 17 Edge edge line of bottom edge 18 Rake face of bottom edge 19 Tip cutting edge 20 Rear edge cutting edge 21 Conventional End mill 22 Inner peripheral cutting edge portion 23 Outer peripheral cutting edge portion 24 End mill of conventional example 25 End face of outer peripheral blade in end mill of conventional example 26 26 Rake face of outer peripheral blade of end mill of conventional example 27 27 End mill of conventional example 2 Edge edge line of outer peripheral blade 28 Barrel polishing device 29 First rotating means 30 Holding stay 31 A second rotating means 32 Abrasive material 33 A third rotating means 34 A rotating direction of the first rotating means 35 A rotating direction of the second rotating means 36 A rotating direction of the third rotating means AA AA Cross-sectional line in the blade straight direction at a position 20% of the blade diameter from the side BB Cross-sectional line in the blade straight direction at a position 60% of the blade diameter from the distal end side of the outer peripheral blade CC The blade diameter from the distal end side of the outer peripheral blade The cross-sectional line in the straight direction of the blade at the position of 20% of DD DD The cross-sectional line in the straight direction of the blade at the position of 60% of the blade diameter from the distal end side of the outer peripheral blade EE Cross sectional line in the direction of the cutting edge of the position FF Cross sectional line in the direction of the cutting edge of the bottom blade at a position 15% of the blade diameter from the tool axis R1 Curvature radius of the cutting edge R2 Curvature radius of the cutting edge of the rear edge R3 Conventional Radius of curvature of the outer peripheral edge of the end mill Ra of radius of curvature of the inner peripheral cutting edge Rb half of the curvature of the outer peripheral cutting edge Diameter d Blade diameter D Shank diameter O Tool axis O 'Main axis of barrel polishing equipment

Claims (5)

  A square end mill having a plurality of bottom blades and outer peripheral blades, and a tip cutting edge portion having a large radius of curvature of a ridge formed from the flank of the outer peripheral blade and the rake face of the outer peripheral blade on the front end side of the outer peripheral blade A rear end cutting edge portion having a small curvature radius is provided on the rear end side of the outer peripheral blade, and the flank of the outer peripheral blade and the rake face of the outer peripheral blade in each outer peripheral blade are each one curved surface. Square end mill characterized by being formed by   2. The square end mill according to claim 1, wherein the length of the tip cutting edge portion is in a region from a joint between the bottom blade and the outer peripheral blade to 30% of the blade diameter.   The square end mill according to claim 1 or 2, wherein a radius of curvature R1 of the tip cutting edge portion is 2 µm or more and 4 µm or less, and a radius of curvature R2 of the trailing edge cutting edge portion is 1 µm or more and 3 µm or less. .   4. The square end mill according to claim 1, wherein a radius of curvature Ra of an inner peripheral cutting edge portion of the bottom blade that forms from a tool axis to a position of 25% of a blade diameter is 1 μm or more and 2 μm. A square end mill having a radius of curvature Rb of an outer peripheral cutting edge portion that forms from the outer periphery to a position of 25% of the blade diameter among the bottom blades and having a curvature radius Rb of 4 μm or more and 6 μm or less.   The square end mill according to any one of claims 1 to 4, wherein a blade portion having a plurality of bottom blades and an outer peripheral blade, a shank portion having a diameter larger than the blade portion, and the blade portion and the shank portion are connected. Square end mill characterized by comprising a neck.

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