JPH0523885B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a reamer having a drill part and a reamer part, and more particularly to a drill reamer with good basic drilling accuracy and hole finishing accuracy.

Conventional technology In general, in the conventional drilling process, after drilling a hole in the material, a core drill is used and then a reamer is used, or a reamer is used immediately without using a core drill to refill the hole. Finishing work was being done. However, since two types of tools are used in the above process, there are problems in that it takes time and increases tool costs. As a solution to this problem, as shown in Figures 8 to 10,
A reamer has been developed in which a single tool includes a drill part 21a that performs the above-mentioned drilling process and a reamer part 21b that performs finishing process. According to this reamer 21,
The above two types of machining can be performed with one tool, the machining time is shortened, the tool cost is not so high, and all of the above problems can be solved.

Problems to be Solved by the Invention However, in the reamer 21 having the above structure, the core thickness is increased in the drill part 21a in order to provide rigidity, so that when the cutting edge is raised, the chisel edge 2
2 is larger than that of the standard drill 3 (see FIG. 4), and as a result, when cutting material with the drill part 21a, a so-called walking phenomenon occurs, causing the drill part 21
The center of rotation of a moves and the drilling accuracy (for example, roundness, straightness, surface roughness, etc.) deteriorates, and when finishing with the reamer part 21b, the drilling accuracy with the drill part 21a is poor. There was a problem in that the finishing process was performed in a state where the center axis of the reamer portion 21b and the center axis of the hole were misaligned, resulting in poor accuracy of the finished hole. Note that the above-mentioned standard drill 3 is, for example, a drill commercially available based on the JIS B 4301 standard for straight shaft drills, and whose core thickness is generally (0.15~
0.18)×D. However, D is the drill diameter.

Therefore, an object of the present invention is to provide a reamer that can perform hole drilling and hole finishing with high precision.

Means for Solving the Problems In order to achieve the above object, the present invention is configured such that a auxiliary groove communicating with the main groove for chip ejection is formed within the re-grinding range of the thick core portion of the drill part. .
That is, in a reamer consisting of a drill part and a reamer part, the drill part has a standard cross-sectional blade shape in which the heel surface and the back surface of the blade, which constitute the main groove for chip ejection, form a substantially smooth curved surface in the axial cross section of the drill part. In contrast, the entire outer part of the heel surface of the heel surface of the standard cross-sectional blade shape, that is, the outer end, or a part, for example, the entire outer end, is made to protrude from the heel surface, and then only the heel part is cut off. The remaining uncut portion protrudes into the main groove for chip ejection, and the back surface of the blade protrudes in a substantially triangular shape from the back surface of the blade of the standard cross-sectional blade shape toward the main groove for chip ejection. The cross-sectional shape is within a predetermined range along the axial direction from the tip, and within the predetermined range and within the re-grindable range from the tip along the axial direction, the standard cross-sectional blade shape is A sub-groove recessed from the heel surface in a substantially U-shape is provided on the heel surface center side of the heel surface.

Effect of the Invention In the above configuration, the chisel edge is made smaller by the auxiliary groove, and when cutting with the drill part, the tip of the drill part does not perform a so-called walking phenomenon with respect to the workpiece, and the center of rotation of the drill part does not move. ,
Cutting resistance is also reduced, drilling can be performed with high accuracy, and the inner circumferential surface of the hole can be finished with the reamed part while the central axis of the reamed part and the central axis of the hole are substantially aligned. The accuracy of the finished hole is improved.

Embodiments Hereinafter, embodiments according to the present invention will be described in detail based on the drawings shown in FIGS. 1 to 7.

Fig. 1 is a side view of a reamer 1 according to an embodiment of the present invention, Figs. 2 and 3 are sectional views of the end face of the drill part 1a and the reamer part 1b, respectively, and Fig. 4 is a sectional view of the blade part of the drill part 1a. Figure 5 is a cross-sectional side view of the main part of the blade,
FIG. 6 is a sectional view taken along the line -- in FIG. 5, and FIG. 7 is a specific front view of the tip of the drill portion 1a. Note that in FIG. 4, the dotted line indicates a conventional standard drill 3 having a standard cross-sectional blade shape in which the heel surface 3b and the blade back surface 3a forming the chip ejection groove form a substantially smooth curved surface in the axial cross section of the drill. The two-dot chain line indicates a conventional high-rigidity drill 2 with a large core thickness. Also,
In FIG. 4, 2b is the back surface of the blade, and 2c is the heel surface.

The reamer 1 has a drill part 1a and a reamer part 1b.
It is roughly composed of.

First, the drill portion 1a will be explained. The drill portion 1a is formed symmetrically with respect to the axis O point in FIG. 4 in the axial cross section of the reamer within a predetermined range along the axial direction from the tip of the reamer 1, and has a pair of chip ejection main grooves. 6, 6 are formed spirally along the axial direction, and the groove wall surface of each curved main groove 6 is provided with a blade back surface 4 and a heel surface 5, respectively.

The back surface 4 of the blade is made thicker than the standard drill 3 by projecting into the main groove 6 in a substantially triangular shape using the standard drill 3 in the axial cross section of the drill portion. That is, the outer side 4 of the back surface 4 of the blade
A is made to protrude like the conventional high-rigidity drill 2, while the center side 4b is depressed from the center side of the high-rigidity drill 2 to reduce the core thickness.

Further, in the axial cross section of the drill portion, the heel surface 5 has a main groove 6 at its outer end 5b as shown by the dashed line in FIG.
A sub-groove 8 that protrudes inward and is recessed in a U-shape from the outer end 5b toward the center is formed in a spiral along the axial direction. Therefore, the outside part 5b of the heel surface 5 is made thicker than the standard drill 3, while the center side is made thicker than the high-rigidity drill 2.
The core thickness is made smaller by concave than standard drill 3. As shown in FIG. 5, the auxiliary groove 8 is formed within a certain range _l2 along the axial direction from the tip side of the drill part, and this range is defined as the range in which the cutting edge of the drill part 1a can be reground. Within the re-grindable range _l2 in which this minor groove 8 is formed, the core thickness dimension _W1 is constant, that is, _the parallel core thickness (0/100 ), forming a parallel portion 8a whose groove bottom surface is parallel to the axial direction of the drill part, and forming an inclined portion 8b inclined at a constant angle from the parallel portion within the remaining range _L2 . Even if re-grinding is performed up to this inclined portion 8b, the size of the chisel edge formed on the tip surface of the blade is the same as that of the standard drill 3 mentioned above.
It is smaller than the chisel edge of the previous model and has excellent cutting performance. Note that the drill portion 1a is formed by, for example, using a grindstone for forming the sub-groove 8 to grind off the heel portion 7 as shown by the solid line in FIG. 4 to enlarge the space of the main groove 6 and improve penetration of the cutting oil. is preferable. In this case, even if the heel portion 7 was shaved off, the life of the drill portion 1a did not decrease due to the decrease in the rigidity of the drill portion 1a.

On the other hand, the reamer part 1b is formed to have a diameter one step larger than the drill part 1a, and is formed point-symmetrically in the axial cross section of the reamer with respect to the center axis O point in FIG. 4, and has four cutting edges. 10,..., 10, and adjacent cutting edges 10, 1 along each circumferential direction.
0, a pair of spiral first grooves 12, 12 for chip ejection which are continuous with the pair of main grooves 6, 6 for chip ejection of the drill part 1a, and a spiral for chip ejection newly formed from the reamer part 1b. The second grooves 11 are provided alternately. The action of this reamer portion 1b is similar to that of a conventionally known reamer.

According to the reamer 1, a hole is initially drilled into the material by the drill portion 1a. That is, when cutting a hole, chips generated by cutting the drill part 1a are removed from the approximately triangular protrusion 4 on the back surface 4 of the blade.
The chips crushed by the chisel edge are guided from the main groove 6 to the first groove 12 along the curved surface of the outer side 4a of c and are well discharged, and the chips crushed by the chisel edge are transferred from the sub groove 8 to the main groove 6 and the first groove 12. It is guided inside and discharged properly. Next, a hole is drilled to form the reamed part 1b.
When the inner circumferential surface of the hole comes into contact with the inner circumferential surface of the hole, the inner circumferential surface of the hole is cut with each cutting blade 10 of the reamer part 1b to obtain roundness, straightness, and surface roughness, and finish the inner circumferential surface of the hole with high precision. . The chips cut by each of the cutting blades 10 are well discharged from the first groove 12 or the second groove 11.

FIG. 7 shows a specific example of the drill portion of the reamer for steel, which is the reamer 1 according to the above embodiment. The core thickness dimension W ₂ of the main groove part is (0.25 to 0.40) D, the groove width ratio is 1:1 to 0.8:1, the helix angle is 25 degrees, and the core thickness dimension W ₁ of the minor groove part is (0.04 to 0.11). D, and the tip angle is
The temperature shall be 135 degrees. However, D is the diameter of the drill part. Then, the line connecting the outer ends of the back sides 4 and 4 of the double blade and the back side 4 of the blade.
The angle α between the tangent of the center side curved surface of the blade is 10° to 15°, the radius of curvature _R1 of the center side curved surface of the blade back surface 4 is (0.1 to 0.2) D, and the angle α from the blade back surface 4 to the heel surface 5 is The diameter _D3 of the curved surface of is φ(0.1~0.2)D,
The radius of curvature R ₂ of the curved surface on the center side of the heel surface 5 is (0.5
~0.8)D, and the distance from the center of the drill part of the boundary between the outer end 5b of the heel surface 5 and the sub-groove 8, that is, the diameter _D2, is φ0.85D. The axial length of the minor groove 8 is l ₂ (see Fig. 5), that is, the axial length from the contact point A between the cutting edge and the minor groove 8 is (0.5 to 1.1)D.
shall be. With this axial length, it is possible to re-grind the same number of times as a conventional drill, and the service life is also comparable to that of a conventional drill. However, in order to extend the service life, the shorter the above length, the better. The core thickness taper in the range between the core thickness dimension W′ and W″ of the inclined portion 8b of the sub-groove 8 is approximately 2/100 to 6/100,
If the core thickness dimension _W1 is φ13.0mm or more, the core thickness taper shall be 4/100.

In addition, in the conventional high-rigidity drill for steel, the groove width ratio is 0.8 to 0.9:1 and the core thickness dimension is (0.2 to 0.45)D, and it is necessary to perform thinning. In addition, standard drills for steel have groove width ratios of 1.3:1 to 1:1,
The core thickness was (0.1 to 0.20)D, and thinning was required.

In addition, the groove width ratio and core thickness dimensions of the drill part 1a are different between drills for light alloys and aluminum and those for steel, and the groove width ratio and core thickness dimensions are determined depending on the respective applications. , it is necessary to eliminate the need for thinning. As a reference example of the drill part for light alloys and aluminum, the groove width ratio is
Increase the torsion angle to 1.5:1 to 1.6:1 and set the torsion angle to 38
There is a drill with a larger core thickness of ~42 degrees, but with the same core thickness as a steel drill.

According to the above embodiment, since the heel surface 5 of the drill part 1a is provided with the sub-groove 8, the core thickness of the drill part 1a is smaller than that of the standard drill 3 or the high-rigidity drill 2, and the chisel edge is also small when the cutting edge is raised. At the same time, the radius of curvature of the groove bottom at the center of the drill part becomes smaller, and as a result, when cutting with the drill part 1a, the biting property against the material to be cut is improved, and the so-called walking phenomenon does not occur and drilling can be performed with high precision. This eliminates the need for thinning the drill portion 1a, and improves the breakability of chips. Also,
When finishing machining is performed with the reamer part 1b following the drill part 1a, the hole is drilled with high accuracy and the axis of the hole and the center axis of the reamer part 1b approximately coincide, so that
The inner circumferential surface of the hole can be uniformly cut by the reamer portion 1b, resulting in a highly accurate finish. Therefore,
In the drill portion 1a, it is possible to reliably solve the problem of the conventional high-rigidity drill 2 in which the skill of thinning affects the drilling accuracy. Further, there is no need to thin the drill portion 1a every time the drill portion is re-grinded, and sufficient cutting can be achieved simply by sharpening the cutting edge at the tip of the drill portion. In addition, since the sub-groove 8 is provided on the center side of the heel surface 5 of the drill part 1a, the chip ejection groove can be made larger than the chip ejection groove of the conventional high-rigidity drill 2 or standard drill 3. , the outer side 4a of the protrusion 4c on the back surface 4 of the blade
Since the chips can be smoothly guided into the chip ejection grooves 8 and 6 along the curved surface, the chip ejection performance is improved. In addition, since the parallel portion 8a is formed in the minor groove 8, the cutting edge portion can be made rigid, and the core thickness dimension of the parallel portion 8a can be measured in the quality inspection process at the manufacturing stage of the drill portion. This makes it possible to stabilize product quality. In other words, if the sub-groove 8 is constructed from only the inclined part without forming a parallel part, when measuring the core thickness dimension in the sub-groove part, for example, if the position of the measuring tip of the micrometer is slightly deviated, the core thickness dimension will be Because of the different values, it was difficult to measure the same location in each drill part 1a, making it difficult to stabilize the quality of the product. In addition, by making the outer end 5b of the heel surface 5 thicker, and by forming a protrusion 4c on the back surface 4 of the blade to make it thicker, the rigidity of the drill part is improved without increasing the core thickness. can be done. Furthermore, in response to the reduced core thickness as described above, the cross-sectional area of the chip ejection groove is larger than that of the standard drill 3 or the high-rigidity drill 2, and the chip ejection performance is improved. In addition, since the hole drilled by the drill part 1a has good accuracy,
The state is the same as when a core drill is passed through, and the load placed on the reamer part 1b is reduced compared to a conventional reamer having a drill part and a reamer part.

In the above embodiment, after the drilling process is completed with the drill part 1a, the inner peripheral surface of the hole is finished with the reamer part 1b. It is also possible to provide a drill so that drilling and reaming can be performed at the same time. Further, an oil hole may be provided to extend the life and improve the precision of the finished hole. Further, a hard film such as titanium nitride (TiN), titanium carbide (TiN), cubic boron nitride (CBN), or the like may be formed on the surface of the reamer 1 by coating.

Effects of the Invention According to the above configuration, by forming the substantially U-shaped sub-groove on the center side of the heel surface of the blade portion of the drill portion, the core thickness is reduced, the chisel edge is reduced, and the center portion of the drill portion is reduced. The radius of curvature of the bottom of the groove is smaller, so when cutting with the drill part, the drill part has better grip on the material to be cut, and the so-called walking phenomenon does not occur, effectively preventing the center of rotation of the drill part from moving. In addition, cutting resistance is reduced, machinability is improved, and chip breakability is also improved. In addition, when finishing machining is performed using the reamer section following the drill section, the above hole is drilled with high precision and the axis of the hole and the center axis of the reamer section roughly match, so the inner peripheral surface of the hole can be cut uniformly with the reamer section. It is possible to finish with high accuracy, and the accuracy of hole roundness, straightness, surface roughness, hole position, etc. is improved. Therefore, it is not necessary to thin the drill part, and the skill of thinning does not affect the accuracy of drilling, so that accurate drilling can be performed without thinning. Further, there is no need to perform thinning every time the drill part is reground, and sufficient cutting can be achieved simply by sharpening the cutting edge at the tip of the drill part. Furthermore, since the sub-groove is provided on the center side of the heel surface of the drill portion, the area of the groove for discharging chips is larger than that of a standard drill or a high-rigidity drill, improving chip discharging performance. In addition, since a parallel portion is formed in the minor groove, it is possible to provide rigidity to the cutting edge. It is possible to stabilize the quality of the product. In other words, if the sub-groove is formed from only the inclined part without forming the parallel part, when measuring the core thickness dimension of each drill part in the sub-groove part using, for example, a micrometer, even if the position of the measuring point of the micrometer is slightly If this happens, the core thickness dimension will differ due to the inclination of the core thickness part, so it is necessary to accurately position the gauge head at the same position in each drill part, and it is extremely difficult to position the gauge head at the same position. Therefore, it was difficult to stabilize the quality of the product. In addition, in the axial cross section of the drill part, the outer end of the heel surface of the blade protrudes into the chip ejection groove, while the back surface of the blade protrudes in a substantially triangular shape toward the chip ejection groove, without increasing the core thickness. , the rigidity of the drill part can be increased, and the efficiency of drilling can be increased. Furthermore, since the back surface of the blade protrudes in a substantially triangular shape, cut chips, that is, chips, are smoothly guided into the chip discharge groove along the outer slope of the substantially triangular protrusion. Furthermore, since the hole drilled by the drill part has good accuracy, the condition is the same as when a core drill is passed through, and the load on the reamer part is reduced compared to a conventional reamer having a drill part and a reamer part.

[Brief explanation of drawings]

FIG. 1 is a side view of a reamer according to an embodiment of the present invention, and FIGS. 2 and 3 are end views of the drill part and the first reamer.
FIG. 4 is a sectional view of the blade of the drill part, FIG. 5 is a sectional side view of the main part of the blade of the drill part, FIG. 6 is a sectional view taken along the line - of FIG. 5, 7th
The figure is a front view of the blade tip of a specific drill part, Nos. 8 to 10.
The figures are a side view of a conventional reamer, an end view of a drill portion, and a sectional view taken along the line X--X in FIG. 8, respectively. DESCRIPTION OF SYMBOLS 1... Reamer according to the embodiment, 1a... Drill part, 1b... Reamer part, 2... Conventional drill, 2
b... Back side of the blade, 2c... Heel side, 3... Standard drill, 3a... Back side of the blade, 3b... Heel side, 4...
...back side of blade, 4a...outside, 4b...center side, 4c
...Protruding part, 5...Heel surface, 5b...Outside end, 6...Main groove for chip ejection, 7...Heel part,
8... Minor groove, 10... Cutting edge, 11... Second groove, 1
2...First groove.

Claims (1)

[Scope of Claims] 1. In a reamer having a drill portion 1a at the tip of the reamer portion 1b, the drill portion 1a has a heel surface 3b forming a chip ejection main groove 6 and a blade back surface 3a in the axial direction of the drill portion. The heel surface 3 of the standard cross-sectional blade shape has a roughly smooth curved surface in cross section.
All or part of the outside portion of the heel surface 5 of the heel surface 5 protrudes into the chip ejection main groove 6 from b, and the blade back surface 4 extends from the blade back surface 3a of the standard cross-sectional blade shape into the chip ejection main groove 6. It has a cross-sectional shape that protrudes in a substantially triangular shape toward the tip within a predetermined range along the axial direction from the tip, and within the predetermined range and within a re-grindable range _l2 along the axial direction from the tip. In the above cross-sectional shape, the reamer is characterized in that a sub-groove 8 recessed in a substantially U-shape from the heel face 3b of the standard cross-sectional blade shape is formed on the heel face center side of the heel face 5.