JP2004345050A - Broaching tool, and broaching method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a broaching tool, and a broaching method, in which an internal spline of a high hardness member is finished to secure coaxial performance to a prepared hole for enabling a tooth face to be machined without causing seizure, welding, or abnormal abrasion. <P>SOLUTION: This broaching tool, for machining a spline or an internal gear, is provided with a guide surface 7 on a tooth bottom part 6 to face the prepared hole in the workpiece keeping a micro-gap to it between a plurality of cutting edges 14 adjoining each other in a circumferential direction. The cutting edge 14 comprises cemented carbide, and hard film is coated at least on a tooth face, a flank, and the guide surface 7. A rake angle θ is within a range of -30°≤θ≤-10°. A forward end surface 8 of the guide surface 7 is provided to be flush with the rake face 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a broaching tool having a number of cutting edges made of cemented carbide arranged in a circumferential direction and an axial direction, and is particularly suitable for processing a high-hardness material whose work material is 45 to 65 HRC after heat treatment. The present invention relates to a tool and a broaching method.
[0002]
[Prior art]
Generally, a broach is provided with a series of cutting blades, each of which includes a rough cutting blade group, a semi-finishing blade group, and a finishing blade group, each having a different cutting amount, and can finish machining in a short time. Suitable for mass production of molded products. In other words, it is characterized in that a deformed shape which cannot be handled by other processing methods can be easily formed, and excellent processing dimensions and finished surface roughness can be obtained without requiring any special skills for the operation. However, when finishing the tooth surface or large diameter of the inner spline of high-hardness material in which the finishing allowance is left by grinding or turning after heat treatment, or broaching, the pilot hole ground by pre-processing Coaxiality is required. In order to solve such a problem, as shown in FIGS. 6 and 7, the tooth bottom 61 of the blade 60 adjacent to the outer periphery of the broaching tool has a small gap between the pilot hole of the workpiece during the cutting process. A guide surface 62 is provided opposite to the guide surface 62, and a flank 64 is provided in front of the guide surface 62. A front end surface 65 of the flank 64 is provided on the same plane as the rake face 63 of the adjacent blade portion 60. I have. Accordingly, a broach tool that prevents the inner diameter from being cut by the corner of the flank 64 and the front end face 65 to prevent the gap from expanding and secures the same axis between the pilot hole and the spline processing portion is disclosed (for example, Patent Document 1). 1).
[0003]
[Patent Document 1]
Jitsuhei 6-11704 (Page 1-3, Figure 1-5)
[0004]
[Problems to be solved by the invention]
However, when the broach described in Patent Document 1 is used for finishing hard materials of 45 to 65 HRC with a high required level of coaxial accuracy, that is, when it is necessary to set a small gap and perform high-speed machining, the guide is used. Surface burn-in, welding, abnormal wear, etc. may occur. Further, there is a problem that the manufacturing cost for forming the flank 64 in the tooth bottom 61 is high.
[0005]
The object of the present invention was made to solve the problems of the prior art, and when finishing the tooth surface, large diameter, or the tooth surface and large diameter of the inner spline of the hard material of 45 to 65 HRC, An object of the present invention is to provide an inexpensive broach tool and a processing method capable of performing processing without seizing, welding, and abnormal wear on a blade portion while maintaining the same axis as a prepared hole.
[0006]
[Means to solve the problem]
In the present invention, a spline, an internal gear, or the like, in which a guide surface opposed to a prepared hole of a workpiece at a small interval during cutting between a plurality of circumferentially adjacent cutting edges is provided at a tooth bottom portion, etc. The cutting edge is made of cemented carbide, and at least the tooth surface, flank surface, and guide surface are coated with a hard coating, and the rake angle θ is −30 ° ≦ θ ≦ −10 °. The above-mentioned object has been attained by providing a broaching tool which is provided within a range and whose front end surface of the guide surface is flush with the rake face of the cutting edge (claim 1). That is, in the processing of an internal spline, an internal gear, or the like of a high hardness material of 45 to 65 HRC, a tooth surface, a flank, and a guide surface are coated with a hard coating, and a front end surface of the guide surface is formed as a rake face of a cutting edge. They were provided on the same plane. Therefore, during cutting, the broach loses balance with the prepared hole of the workpiece, and the center of the broach is reduced by the gap between the guide surface provided at the tooth bottom of the broach and the prepared hole of the workpiece. Even if the displacement occurs, the front end face of the guide surface is flush with the rake face of the cutting edge, and the guide face has a clearance angle of 0 and a negative rake angle of -10 ° or less. Even if the flank is not provided as in the conventional case, the corners of the guide surface and the rake face do not cut into the prepared hole and cut. If the rake angle is larger than -10 °, the strength of the cutting edge will be insufficient during high-speed machining, and chipping will occur, and if it is smaller than -30 °, the sharpness will be poor, so the rake angle θ is −30 ° ≦ θ ≦ − 10 °.
[0007]
Further, in the finishing of a workpiece of 45 to 65 HRC, the gap between the pilot hole provided on the workpiece and the guide hole provided in the broach with the workpiece whose dimensional variation has been reduced by grinding or turning after the heat treatment is 5 to 60 μm in diameter. The above-mentioned problem has been solved by a broaching method for performing a finishing process at a processing speed of 40 to 80 m / min using the broaching tool of the present invention described in claim 1 (claim 2). This is because the guide surface is coated with a hard coating, so that even with high-speed processing of 40 to 80 m / min, it contacts the prepared hole with the workpiece whose dimensional variation has been reduced by grinding or turning after heat treatment. No seizure or abnormal wear occurs. If the gap between the pilot hole of the workpiece and the guide surface is smaller than 5 μm, abnormal wear occurs due to rubbing and the like, and if it is larger than 60 μm, the required accuracy cannot be obtained. Was set to 5 to 60 μm.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a broaching tool according to the present invention will be described with reference to the drawings, but the present invention is not limited thereto. FIG. 1 is a partially enlarged perspective view of a blade portion of a broach tool showing an embodiment of the present invention, FIG. 2 is a vertical sectional view of a guide surface of FIG. 1, and FIG. 4 is an enlarged view of a main part of FIG. 3, and FIG. 5 is a side view of a broach tool of the present invention. As shown in FIG. 5, one end of the broach main body 50 of the broaching tool 58 has a front grip portion 51 for pulling the broaching tool 58 in the processing direction, a front guide portion 52, and a large number around the axis and in the axial direction (outer circumference) 53. The arranged blade portions 54 and rear escape portions 55 are sequentially formed, and a rear grip portion 56 is provided at the other end. The broaching tool 58 is pulled through the hole of the workpiece in the direction of the front grip 51, and the blade 54 processes a spline of the workpiece hole. This configuration is general, and the description is omitted.
[0009]
In particular, in the present invention, as shown in FIGS. 1, 2, and 4, the blade portion 1 has a rake face 2 having a substantially trapezoidal involute cross section, a side face 3 extending axially rearward from the rake face, and a rake face 2. And an upper surface 5 extending axially rearward from the ridge line. A guide surface 7 is provided on a tooth bottom 6 of the blade 1, and a front end face 8 of the guide surface 7 is rake face 2. And on the same plane. No flank is provided unlike the conventional case. The upper surface 5 and the side surface 3 are also coated with a hard coating, and in order to increase the strength of the cutting edge, the angle between the surface 9 perpendicular to the broach axis and the rake surface 2, that is, the rake angle θ is an obtuse angle of −10 °. . At this time, since the angle between the front end face 8 of the tooth bottom and the guide surface 7 is obtuse, the corner portion 10 does not cut into the prepared hole 11, but the corner portion 10 is further sharpened with a small radius. You may. As shown in FIGS. 3 and 4, the involute tooth surface 13 of the work 12, which has been machined by leaving a margin in the pre-machining, is machined by the cutting edge 14 of the foam. The diameter of the guide surface 7 is The gap of w = 15 μm is set on one side with respect to the prepared hole 11 of the work 12.
[0010]
【Example】
Using such a broach, a lubricating mist of 10 cc per minute was jetted to the processing portion to process at a processing speed of 60 m / min. As a result, it was possible to perform processing without seizure in the prepared hole and abnormal wear, and the coaxiality between the prepared hole and the processed involute spline tooth surface was 10 μm or less, and good processing accuracy was obtained.
[0011]
【The invention's effect】
As described above, according to the present invention, the cutting edge is made of a cemented carbide, and at least the tooth surface, the flank surface, and the guide surface are coated with a hard coating, and the rake angle θ is −30 ° ≦ θ ≦ −10 ° or less. And, since the front end face of the guide surface is flush with the rake face, the tooth surface or the large diameter of the inner spline of a hard material of 45 to 65 HRC is secured with high precision coaxial with the prepared hole, The surface can be machined without seizure, welding and abnormal wear.
[0012]
In the finishing of a workpiece of 45 to 65 HRC, the gap between the pilot hole provided on the broach and the pilot hole provided in the broach so that the finishing allowance remains after the heat treatment is 5 to 60 μm. Since the finish processing is performed at a processing speed of 40 to 80 m / min using the broach tool of the present invention, a method of processing a broach tool which can secure a high coaxiality with high accuracy and can perform high-speed processing without seizure, welding, and abnormal wear of the tooth surface is provided. It can be provided.
[Brief description of the drawings]
FIG. 1 is a partially enlarged perspective view of a blade portion of a broach tool showing an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of a guide surface of FIG. 1;
FIG. 3 is a schematic cross-sectional view perpendicular to the axis of the broaching tool of the present invention during machining of a workpiece.
FIG. 4 is an enlarged view of a main part of FIG. 3; .
FIG. 5 is a side view of the broaching tool.
6 is a partially enlarged perspective view of a blade portion of a conventional broaching tool. FIG. 7 is a longitudinal sectional view of a guide portion of the blade portion in FIG.
[Explanation of symbols]
2 rake face 6 tooth bottom 7 guide face 8 front end face 11 pilot hole 14 cutting edge 58 broach tool θ rake angle

Claims (2)

A broaching tool for machining splines and internal gears with a guide surface at the bottom of the tooth that opposes the pilot hole of the workpiece with a small gap during cutting between a plurality of circumferentially adjacent cutting edges. And
The cutting edge is a cemented carbide, at least tooth surface, flank, and the guide surface is coated with a hard coating, the rake angle θ is in the range of −30 ° ≦ θ ≦ −10 °, and the A broaching tool, wherein a front end face of a guide surface is provided on the same plane as a rake face of the cutting edge. In the finishing of a workpiece having a diameter of 45 to 65 HRC (Rockwell hardness C scale), the gap between the pilot hole provided on the broach and the prepared hole ground or turned after the heat treatment is 5 to 60 μm in diameter. A broaching method using the broaching tool according to claim 1 at a processing speed of 40 to 80 m / min.

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