JP2008188700A - Radius end mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve smoothness of a machined face of a work in pick feed cutting, and to sufficiently improve machining efficiency. <P>SOLUTION: In the radius end mill 1, a cutter bit 3 having a half-arced cutting edge 3c in a plane in a diameter direction including a straight line S of a tool body 2 is provided protruding forward via a cutter bit forming part 4 on a tip face 2a of the tool body 2 rotating around an axis S. A blade surface 3a to be used as a cutting face, and a blade surface 3b to be used as a flank relief are respectively formed on both sides along the cutter bit 3, and in the cutter bit 3, an arced vertex 5 of the cutting edge 3c is decentered for just a predetermined eccentric distance d in an outer circumference direction from an axis position (a rotation center) C1 of the tool body 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a radius end mill that finishes a processed surface of a workpiece flat by pick feed cutting.

Conventionally, a substantially arc-shaped cutting edge is provided at the tip of a tool body that rotates about an axis, and a rake face and a flank are formed on both sides along the cutting edge. There is known a ball end mill that is provided in parallel to a plane to be included and shifted by a predetermined distance from the axis of the tool body in a direction perpendicular to the plane (for example, see Patent Document 1).
JP 2004-142055 A

The ball end mill can give the workpiece a peripheral speed near the center of the cutting edge by shifting the cutting edge from the axis of the tool body, reducing the amount of wear of the cutting edge, It can be finished with high precision. However, in the ball end mill, the cutting edge is shifted from the axis of the tool body, but the amount of shift is small, and the cutting edge is moved from the axis of the tool body in the direction perpendicular to the plane including the cutting edge. Because of the parallel movement, when pick-feed cutting is performed, the pitch of the lateral feed is set to be large from the relation of the surface roughness of the workpiece processing surface determined from the radius of the arc of the cutting edge and the size of the pitch of the lateral feed. There is dissatisfaction that the machining efficiency of the workpiece cannot be improved sufficiently.
By using a radius end mill, the workpiece can be machined with a large lateral feed pitch. However, in the case of pick feed cutting with a normal radius end mill, it is adjacent by setting the rake angle of the cutting edge. There is a problem that a step is generated in the overlapping portion of the vertical feeds, and they are combined to roughen the cutting surface and a good finished surface cannot be obtained.

  The present invention has been made in view of the above circumstances, and provides a radius end mill that can improve the flatness of the work surface of a workpiece in pick-feed cutting and can sufficiently improve the working efficiency. With the goal.

The present invention is characterized by the following points in order to solve the above problems.
That is, in the radius end mill according to claim 1 of the present invention, a cutting edge having a cutting edge having an arc shape in a diametrical plane including the axis of the tool body is formed at the tip of the tool body rotating about the axis. A radius end mill provided so as to protrude and having a rake face and a flank face formed on both sides thereof along the cutting edge of the cutting edge,
The cutting blade is characterized in that the vertex of the arc of the cutting edge is decentered by a predetermined distance in the outer circumferential direction from the rotation center of the tool body.

  The radius end mill according to claim 2 is a radius end mill according to claim 1, wherein the cutting edge of the cutting edge is formed in a semicircular arc symmetrical about the apex, in contact with the outer periphery of the tool main body on the outer peripheral side of the tool main body. It is characterized by being.

  A radius end mill according to claim 3 is the radius end mill according to claim 1, wherein the cutting edge of the cutting edge is formed in an arc having an angle smaller than a quarter arc at a portion located outside the tool body from the apex. The part located in the rotation center side of the tool main body is formed in a quarter arc.

The present invention has the following excellent effects.
That is, according to the radius end mill according to the first aspect, in the pick-feed cutting, the lateral feed amount can be significantly increased as compared with the ball end mill, and the finishing of the plane of the workpiece W can be performed with high efficiency. . Further, in the adjacent vertical feed cutting region, it is possible to prevent burrs from being generated on the cutting surfaces of the overlapping parts of the workpiece on the outer peripheral side of the rotational movement locus of the cutting blade. A step that becomes higher than the cutting region does not occur, and the entire processed surface of the workpiece can be cut flat, and a good finished surface can be obtained.

  Moreover, according to the radius end mill which concerns on Claim 2, the function as a normal radius end mill can be fulfill | performed, and it can continue a favorable finishing surface in shape processing.

  Further, according to the radius end mill according to claim 3, by increasing the eccentric distance from the center of rotation of the tool body at the apex of the cutting blade and increasing the radius of the arc of the cutting blade to widen the cutting width of the cutting blade. Since the cutting area in the transverse feed direction by the cutting blade can be widened, the pitch of the transverse feed of the tool can be increased, and the cutting efficiency can be further improved.

Hereinafter, a radius end mill according to an embodiment of the present invention will be described with reference to the drawings.
1 to 4 show a radius end mill 1 according to a first embodiment of the present invention. The radius end mill 1 includes a tool main body 2 and an arcuate cutting edge 3 provided on a tip surface 2 a of the tool main body 2. The tool body 2 is a columnar member having a circular cross section with a predetermined diameter and a predetermined length, the base end 2b side is attached to a main shaft of a machine tool or the like, and the axis S is made to coincide with the axis of the main shaft around the axis. It is designed to rotate.

  The tip surface 2a of the tool body 2 is integrally provided with a cutting edge forming portion 4 that protrudes forward at a position eccentric from the axial position (rotation center) C1 of the axis S of the tool body 2 to the outer peripheral side in the diameter direction. It has been. The cutting edge forming portion 4 is parallel to a plane including a diametrical straight line L1 passing through the axial position C1 of the tool body 4, and the tip of the tool body 2 is separated from the plane by a predetermined equal distance H / 2. Side wall surfaces 4a, 4a provided perpendicular to the surface 2a, and a tip surface of the tool body 2 perpendicular to the side wall surfaces 4a, 4a at a position close to the axial position C1 side of the tool body 2 along the straight line L1 A front wall surface 4b provided perpendicularly to the front wall surface 4b, and provided on the opposite side of the front wall surface 4b (the outer peripheral side of the tool body 2), and gradually from both intersections e of the outer peripheral surface of the tool body 2 and the straight line L1. And a pair of inclined surfaces 4c and 4d inclined so as to approach the center side, and are formed in a substantially pentagonal shape in plan view.

  The tip of the cutting blade forming portion 4 is a straight blade that forms an arc shape in a plane along the axis S including the straight line L1 (in the diametrical plane including the axis S) and extends along the plane. The cutting edge 3 is formed. The cutting blade 3 is made of a cemented carbide, a cermet, a CBN sintered body (cubic boron nitride), a cemented carbide composed of a diamond sintered body (PCD), single crystal diamond, or the like, as shown in FIG. As described above, when viewed from the front, the tool body 2 is decentered by a predetermined eccentric distance d from the axial position C1 in the outer circumferential direction, and has a center C2 at a position away from the tip surface 2a of the tool body 2 by a predetermined distance h. It has a cutting edge 3c formed in a semicircular arc having a radius r. A portion of the cutting edge 3 on the outer peripheral side of the tool body 2 of the cutting edge 3c is a ridge line portion 4e at an intersection e of the inclined surfaces 4c and 4d of the cutting blade forming portion 4 extended from the outer periphery of the tool main body 2 to the front. The portion of the tool body 2 near the axis position C1 extends from the end of the semicircle to the upper surface of the stepped portion 4f of the cutting edge forming portion 4 as a tangential ridgeline. That is, the cutting edge 3 is formed in a semicircular arc symmetrical about the vertex 5 with the cutting edge 3c contacting the outer periphery of the tool body 2 on the outer periphery side of the tool body 2 in a front view.

In addition, the cutting edge 3 extends from a plane 6 orthogonal to each cross section in the cross section direction in any cross section in a plane orthogonal to the plane including the straight line L1 and passing through the center C2 of the arc of the cutting edge 3. The cutting edge 3c is composed of a ridge line formed in a mountain shape by intersecting a pair of blade surfaces 3a, 3b inclined at a predetermined inclination angle θ1, θ2, and the outer peripheral side of the tool body 2 of the blade surfaces 3a, 3b is The cutting blade forming portion 4 is smoothly connected to the inclined portions 4c and 4d, respectively. Therefore, the cutting edge 3 is formed into a flat shape of the abacus balls in a plan view, and is formed into a shape obtained by dividing the abacus balls by the axial dividing surface as a whole.
When the tool body 2 rotates in the arrow direction, the preceding one blade surface 3a forms a negative rake surface on one side of the cutting blade 3, and the other blade surface 3b moving backward forms a flank surface. When the tool body 2 rotates in the opposite direction, the blade surface 3b forms a rake surface, and the blade surface 3a forms a flank surface.

When the blade surface 3a is a rake surface, the inclination angle (rake angle) θ1 is set in a range of 20 ° to 70 °, and the inclination angle θ2 of the blade surface 3b serving as a flank surface is 30 ° to 80 °. And the cutting angle that is the sum of the inclination angles θ1 and θ2 is set in the range of 50 ° to 150 °. When a margin 7 having a width b of 0.01 to 0.1 mm is provided in the ridge line portion (cutting edge 3c) of the cutting edge 3 along the direction of the axis L2 of the center C2 of the arc of the cutting edge 3 (cutting edge 3c). Even if the work material is a high-hardness material, it is possible to obtain a good finished surface while suppressing tool breakage. However, when cutting a normal work material, the margin 7 may be omitted.
In addition, a chamfered portion 2 c inclined by about 45 ° with respect to the axis S of the tool body 2 except for the vicinity of the cutting edge forming portion 4 is provided on the outer peripheral portion of the tip of the tool body 2. A chamfered portion 2d along the circumferential direction is also provided on the outer periphery.

  In the radius end mill 1 according to the embodiment configured as described above, the tool main body 2 is mounted on the spindle of the machine tool via the base end 2b side, and rotates in the direction of arrow I in FIG. However, given a predetermined cutting depth t to the workpiece W, for example, as shown in FIG. 5, the workpiece W is longitudinally fed in the direction of arrow X in the x direction at a predetermined feeding speed. Surface finishing is performed. When the vertical feed reaches a predetermined stroke, the feed is laterally fed (pick feed) in the y direction perpendicular to the vertical feed direction by 1 pitch P at the stroke end, and then opposite to the vertical feed direction. Moves vertically in the direction of the arrow and returns to the original stroke end. Further, similarly, the vertical feed and the horizontal feed are repeated to finish the surface finishing of the surface of the predetermined area of the workpiece W.

  In the pick-feed cutting by the radius end mill 1, the cutting edge 3 has an average diameter that is twice the eccentric distance d from the axial position C1 of the tool body 2 to the vertex 5 of the cutting edge 3, as shown in FIG. The workpiece W is vertically fed while drawing a trochoidal curvilinear rotational movement locus k having a cutting width G corresponding to the cutting depth t with respect to the workpiece W in plan view. Cutting is continued by being laterally fed by a pitch P of a distance slightly smaller than the average diameter D.

Accordingly, the lateral feed amount (pitch P) can be greatly increased as compared with the conventional ball end mill, and the finishing of the plane of the workpiece W can be performed with high efficiency. In the adjacent vertical feed cutting region, the outer peripheral portions of the rotational movement locus k of the cutting blade 3 overlap each other, but the cutting blade 3 has a rake angle θ1 that is a relatively large predetermined negative angle as described above. Therefore, burrs can be prevented from occurring on the cutting surface of the workpiece W, and burrs are combined in the overlapping portion M and interfere with each other, resulting in a rough finish surface. Therefore, the entire processed surface of the workpiece W can be cut flat and a good finished surface can be obtained.
Further, in the radius end mill 1, the cutting edge 3 c of the cutting edge 3 is formed in a semicircular arc symmetrical about the vertex 5, which is in contact with the outer periphery of the tool body 2 on the outer periphery side of the tool body 2. Therefore, it can function as a normal radius end mill, and a good finished surface can be continued in the shape processing.

  Next, FIGS. 6 to 9 show a radius end mill 10 according to a second embodiment of the present invention. In contrast to the radius end mill 10, the radius end mill 1 is formed in a symmetric semicircular arc centering on the vertex 5, in which the cutting edge 3 c of the cutting edge 3 is in contact with the outer periphery of the tool body 2 on the outer peripheral side of the tool body 2. The edge 3c of the cutting edge 3A is formed in an arc having an angle smaller than the quarter arc by the part located outside the tool body 2 from the vertex 5, and is positioned on the axis position (rotation center) C1 side of the tool body 2 from the vertex 5. The portion to be formed is a quarter circle. Since other basic configurations are the same as those of the radius end mill 1, the same or similar components are denoted by the same reference numerals, and description thereof is omitted.

  In the case of the radius end mill 10, the radius r of the arc of the cutting edge 3c of the cutting edge 3A is set larger than the radius of the arc of the cutting edge 3c of the cutting edge 3 of the radius end mill 1, and the center of the arc of the cutting edge 3c of the cutting edge 3A is set. The eccentric distance d from C2 to the axial position C1 of the tool body 2 is also set larger than that of the cutting blade 3, and the overall thickness H of the cutting blade 3A is also thicker than the thickness of the cutting blade 3. And the part corresponding to the outer peripheral side of the tool main body 2 of the cutting blade formation part 4 is formed in the circular arc surface 4g by planar view as an extension surface of the outer peripheral surface of the tool main body 2 to the position which contacts the said cutting blade 3A. . In addition, although the part by the side of the axial line C1 of the said cutting-blade 3A has stopped before this axial line position C1, you may make it reach to the other side exceeding this axial line position C1.

  According to the radius end mill 10 according to the second embodiment, the finishing process is performed by pick-feed cutting on the plane of the workpiece W in the same manner as the radius end mill 1 according to the first embodiment. Similar effects can be achieved. In addition, the cutting edge 3c of the cutting edge 3A is formed in an arc having an angle smaller than a quarter circle at the outer side of the tool body 2 from the vertex 5, and the axial position (rotation center) C1 of the tool body 2 from the vertex 5 Since the portion located on the side is formed in a quarter arc, the eccentric distance d of the cutting blade 3A from the axial position C1 of the tool body 2 is increased, and the cutting width G of the cutting blade 3A is increased. Thus, the cutting area in the lateral feed direction by the cutting edge 3A can be widened, and thereby the pitch P of the lateral feed of the tool can be taken larger, and the cutting efficiency can be further improved as compared with the case of the radius end mill 1. Can be improved. Furthermore, since the thickness H of the cutting edge 3A can be increased, the rigidity thereof can be increased, and the high-hardness work material can be cut well without breaking.

  As described above, the radius end mills 1, 10 according to the embodiment have an arcuate shape in the diametric plane including the axis S of the tool body 2 on the tip surface 2 a of the tool body 2 rotating around the axis S. A cutting edge 3 having a cutting edge 3c is provided so as to protrude forward through the cutting edge forming portion 4, and a cutting edge 3a as a rake face and a cutting edge as a flank on each side of the cutting edge 3 In the radius end mill in which 3b is formed, the cutting edge 3 is configured such that the apex 5 of the arc of the cutting edge 3c is eccentric from the axial position (rotation center) C1 of the tool body 2 by a predetermined eccentric distance d in the outer circumferential direction. ing.

  Therefore, according to the radius end mills 1 and 10 according to the above-described embodiment, in the feed feed cutting, the lateral feed amount (pitch P) can be significantly increased as compared with the ball end mill, and the work W can be efficiently performed. Plane finishing can be performed. Further, in the adjacent vertical feed cutting region, it is possible to prevent burrs from occurring on the cutting surfaces of the workpieces W of the overlapping portions M on the outer peripheral side of the rotational movement locus k of the cutting blades 3 and 3A (the cutting edge 3c). Thus, there is no step which becomes higher than the other cutting regions in the overlapping portion M, and the entire processed surface of the workpiece W can be cut flat, and a good finished surface can be obtained.

In the radius end mills 1 and 10 according to the embodiment of the present invention, the upper surface of the stepped portion 4f of the cutting edge forming portion 4 is flush with the tip end surface 2a of the tool body 2, and the stepped portion 4f and the front wall surface are formed. 4b may be eliminated, and the blade surfaces 3a and 3b of the cutting blades 3 and 3Ac on the axis position C1 side may be extended perpendicularly to the tip surface 2a until reaching the tip surface 2a. The position of the center C2 of the radius r is made to coincide with the tip surface 2a of the tool body 2 (the distance h is set to zero), and the protruding length of the cutting blades 3, 3Ac from the tip surface 2a of the tool body 2 is reduced. You may do it.
Furthermore, although the example which provided the radius end mill 1 which concerns on embodiment of this invention 1,10 only the said cutting blade 3,3A was shown, this invention is not restricted to this, Two or more can be provided. .

It is a top view which shows the radius end mill which concerns on the 1st Embodiment of this invention. It is also a front view. Similarly, it is a right side view. Similarly, it is a left side view. It is explanatory drawing of the pick feed cutting by a radius end mill. It is a top view which shows the radius end mill which concerns on the 2nd Embodiment of this invention. It is also a front view. Similarly, it is a right side view. Similarly, it is a left side view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,10 Radius end mill 2, Tool main body 2a Tip surface 3, 3A Cutting edge 3a, 3b Cutting edge 3c Cutting edge 4 Cutting edge forming part 5 Vertex 7 Margin C1 Axis position (rotation center)
C2 Arc center d Eccentric distance H Thickness S Axis P Pitch θ1, θ2 Tilt angle

Claims (3)

A cutting edge having an arcuate cutting edge in a diametrical plane including the axis of the tool body is provided on the front end surface of the tool body rotating around the axis so as to protrude forward, and along the cutting edge of the cutting edge A radius end mill with rake face and flank face formed on both sides,
The radius end mill is characterized in that the cutting edge of the cutting edge is decentered by a predetermined distance in the outer circumferential direction from the rotation center of the tool body.   2. The radius end mill according to claim 1, wherein the cutting edge of the cutting edge is formed in a semicircular arc that is symmetric with respect to the apex and is in contact with the outer periphery of the tool main body on the outer peripheral side of the tool main body.   The cutting edge of the cutting blade is formed such that a portion located outside the tool body from the apex is formed in an arc having an angle smaller than a quarter arc, and a portion located on the rotation center side of the tool body from the apex is formed in a quarter arc. The radius end mill according to claim 1, wherein:

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