JP2008161971A - Broach - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a broach capable of extending the tool service life by reducing a processing load. <P>SOLUTION: The broach is equipped with a plurality of spline cutting teeth 21 provided in the axial direction and performing cutting with respect to a workpiece W outwardly in the radial direction; and with a plurality of plastic finishing teeth 31 provided in the axial direction in the rear of the spline teeth 21, performing plastic forming with respect to a processed part Wb of the workpiece W cut by the spline cutting teeth 21 toward the circumferential direction and finishing the processed part Wb as a tooth groove Wd. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a broach for processing a groove shape on the surface of a workpiece.

  Among parts used for automobiles, construction vehicles, machine tools, etc., there are many parts having complicated groove shapes such as key grooves, spline grooves, serration grooves, and gear teeth grooves on the surface thereof. Broaching is carried out to perform such complicated groove shapes from roughing to finishing with a single pass.

  Broaching is a process of grooving using an axial tool called a broach. And this broach has various cutting blades arranged in multiple stages in its axial direction, and when performing broaching, after inserting the broach into a prepared hole pre-worked in the workpiece, pulling out, Alternatively, the groove can be machined on the surface of the workpiece by pushing in and moving in the axial direction.

  However, in broaching, since the broach penetrates and moves through the lower hole of the workpiece, the outer diameter of the broach is set smaller than the inner diameter of the lower hole. As a result, a slight gap is generated between the broach and the pilot hole, and the workpiece is not sufficiently centered by the gap.

  In view of this, various broaches have been provided that have improved concentricity with the workpiece during machining. Such conventional broaches are disclosed in, for example, Patent Documents 1 and 2.

JP 2004-160559 A JP 2004-322271 A

  However, in the broach of patent document 1, since plastic working is performed over the entire inner peripheral surface of the workpiece, the plastic working area becomes wide, and a large working load acts on the broach. Moreover, in the broach of patent document 2, since a groove | channel shape is formed only by plastic processing, a big processing load will act like patent document 1. FIG. As a result, the broaches of Patent Documents 1 and 2 may be damaged during repeated use, leading to a reduction in tool life.

  Therefore, this invention solves the said subject, and it aims at providing the broach which can extend a tool life by reducing a processing load.

The broach according to the first invention for solving the above-mentioned problems is
A plurality of cutting edges that are provided in the axial direction and perform cutting toward the radially outer side of the workpiece;
A plurality of parts are provided in the axial direction behind the cutting edge, and plastic working is performed in a circumferential direction on a work part of the work piece cut by the cutting edge, and the work part is formed into a predetermined groove shape. And a finishing blade for finishing.

The broach according to the second invention for solving the above-mentioned problem is
In the broach according to the first invention,
A flank is formed at the rear of the finishing blade.

  Therefore, according to the broach according to the present invention, the machining allowance of the finishing blade can be reduced, so that the load during plastic working is reduced and the tool life can be extended.

  Hereinafter, the broach according to the present invention will be described in detail with reference to the drawings.

  1 is a schematic configuration diagram of a broach according to a first embodiment of the present invention, FIG. 2A is a cross-sectional view taken along arrow AA in FIG. 1, and FIG. 2B is an enlarged view of a P portion in FIG. 3 is a longitudinal sectional view of the cutting blade portion, FIG. 4A is a sectional view taken along the line BB in FIG. 1, FIG. 4B is an enlarged view of a Q portion of FIG. Fig. 6 is a longitudinal sectional view of the plastic blade, Fig. 6 is a diagram showing the cross-sectional shape of the plastic finishing blade of each stage on the pitch circle, Fig. 7 is a side perspective view of the plastic finishing blade, and Fig. 8 (a) is a front view of the workpiece. 8 (b) is an enlarged view of the R portion of FIG. 8 (a), FIG. 9 (a) is a diagram showing the machining state of the workpiece when it is sequentially cut by the spline blades of each stage, and FIG. 9 (b). ) Is a diagram showing a machining state of a workpiece when plastic machining is sequentially performed by the plastic finishing blade of each stage, and FIG. 10 is a side perspective view showing the shape of another plastic finishing blade.

  The broach 1 shown in FIG. 1 is a tool for machining the tooth groove Wd on the inner peripheral surface of the workpiece W by being inserted into a prepared hole Wa previously machined in the workpiece (workpiece) W (FIG. 8). (See (a) and (b)). The broach 1 includes a front shank portion 10, a cutting blade portion 20, a plastic blade portion 30, and a rear shank portion 40 from the front to the rear.

  As shown in FIG. 1, the front shank part 10 has a front support part 11 provided at the front end thereof and a front guide part 12 provided at the rear end thereof. The front support portion 11 is supported by a broaching machine (not shown). Moreover, the front guide part 12 has the front guide part 12a and the rear guide part 12b. The front guide portion 12a is formed in a tapered shape so that its outer diameter gradually increases from the front to the rear. On the other hand, the rear guide portion 12b is formed continuously from the rear end of the front guide portion 12a and has an outer diameter that is the same columnar shape as the rear end of the front guide portion 12a. That is, the work W is centered by inserting the rear guide portion 12b into the lower hole Wa of the work W during processing.

  As shown in FIGS. 1 to 3, the cutting blade portion 20 is provided with a plurality of spline blades 21. The spline blade 21 is provided with Sn stages (n corresponds to the number of stages of the spline blade 21) at equal angular intervals in the circumferential direction on the outer peripheral surface of the shaft portion of the broach 1 (cutting blade portion 20) and at equal intervals in the broach axis direction. It has been. The Sn-stage spline blades 21 arranged in the broach axis direction are formed such that the height gradually increases from the first stage to the Sn stage. That is, the amount of increase in the height from the previous stage becomes the cut amount in the spline blade 21 of each stage.

  As shown in FIGS. 1 and 4 to 7, the plastic blade portion 30 is provided with a plurality of plastic finishing blades 31. The plastic finishing blade 31 has Bn stages (n is the number of stages of the plastic finishing blade 31) at equal angular intervals in the circumferential direction on the outer peripheral surface of the shaft part of the broach 1 (plastic blade part 30) and at equal intervals in the broach axis direction. ) Is provided. The Bn-stage plastic finishing blades 31 arranged in the broach axis direction are formed to have the same height, and the tooth thickness gradually increases from the first stage to the Bn stage. It is formed as follows. Furthermore, in each stage of the plastic finishing blade 31, each tooth surface length (land width) is formed to the same length, and each tooth surface is formed by a surface parallel to the tooth surface and the broach axis. An approach angle that is an angle is formed by α.

  The plastic finishing blade 31 includes a front inclined surface 31a, an upper inclined surface 31b, a rear vertical surface 31c, left and right approach surfaces 31d, and left and right straight lands 31e. The front inclined surface 31a is inclined so as to become higher toward the rear. The upper inclined surface 31b is inclined so as to become higher from the rear end of the front inclined surface 31a toward the rear. The rear vertical surface 31c is formed so as to be orthogonal to the broach axis. The left and right approach surfaces 31d are formed at the approach angle α. The left and right straight lands 31e are formed parallel to the broach axis, that is, with an approach angle of 0 degree, and constitute a tooth surface that plastically processes the workpiece W together with the approach surface 31d.

  As shown in FIG. 1, the rear shank portion 40 has a rear guide portion 41 provided at the front end thereof and a rear support portion 42 provided at the rear end thereof. The rear guide portion 41 is disposed in the opening of the workpiece W at the end of machining, and holds the workpiece W. The rear support portion 42 is supported by a broaching machine (not shown).

  Next, an operation when processing using the broach 1 described above will be described.

  First, as shown in FIG. 8A, after forming a pilot hole Wa to the extent that the rear guide portion 12b of the broach 1 can pass through the work W, the work W is placed on the broaching machine. On the other hand, the broach 1 is fixed to the broaching machine via the rear support part 42 so as to face the prepared hole Wa of the workpiece W.

  Next, the broach 1 is passed through the pilot hole Wa while moving the workpiece W toward the broach 1. At this time, since the workpiece W is installed without being fixed on the broaching machine, the front guide portion 12a and the rear guide portion 12b of the front guide portion 12 are sequentially passed through the lower hole Wa of the workpiece W, The workpiece W moves smoothly and is centered.

  Next, with the workpiece W penetrating through the broach 1, the front support portion 11 of the broach 1 is fixed to the broaching machine. And the cutting blade part 20 moves to the prepared hole Wa of the workpiece | work W by pushing out the broach 1 ahead, and cutting is performed. At this time, as shown in FIG. 9A, the first-stage spline blade 21 sequentially passes through the pilot hole Wa of the workpiece W from the Sn-stage spline blade 21, and finally the Sn-stage spline. A workpiece Wb having a cross-sectional shape substantially the same as the tooth profile of the spline blade 21 is formed in a straight line at equal angular intervals in the circumferential direction of the inner peripheral surface of the workpiece W. That is, in the cutting blade portion 20, only the cutting process on the workpiece W to the radially outer side of the broach 1 is performed.

  Next, the broach 1 is further pushed forward, so that the plastic blade portion 30 moves into the workpiece W and plastic processing is performed. At this time, as shown in FIG. 9 (b), the first-stage plastic finishing blade 31 through the Bn-stage plastic finishing blade 31 sequentially pass through the workpiece Wb of the workpiece W. The plastic machining allowances Wc on both sides of the workpiece Wb are sequentially plastically processed simultaneously. And as shown in FIG.8 (b), when the plastic working in the plastic finishing blade 31 of a Bn stage is complete | finished, the tooth groove Wd of a predetermined shape will be formed in the workpiece | work W. FIG. That is, in the plastic blade portion 30, only plastic working in the circumferential direction of the broach 1 is performed on the workpiece W.

  As shown in FIG. 10, a chamfered flank 31f may be formed behind the straight land 31e. Thereby, the strength of the plastic finishing blade 31 is improved and the straight land 31e is prevented from being damaged.

  Therefore, according to the broach according to the present invention, the workpiece W is formed by cutting the workpiece W radially outward with the spline blade 21 and then forming the workpiece Wb with the plastic finishing blade 31. By performing plastic working on the processed portion Wb in the circumferential direction to form the tooth groove Wd on the inner peripheral surface of the work W, the plastic working allowance Wc of the work W can be reduced. As a result, the processing load on the plastic finishing blade 31 is reduced, so that the tool life of the broach 1 can be extended. Moreover, since the strength of the plastic finishing blade 31 is improved by forming the flank 31f at the rear part of the plastic finishing blade 31, the tool life can be further extended.

  11 is a schematic configuration diagram of a broach according to a second embodiment of the present invention, FIG. 12A is a cross-sectional view taken along the line CC of FIG. 11, and FIG. 12B is an enlarged view of an S portion of FIG. FIG. 13 is a longitudinal sectional view of the cutting blade portion, FIG. 14A is a sectional view taken along the line DD in FIG. 11, FIG. 14B is an enlarged view of a T portion in FIG. Fig. 16 is a longitudinal sectional view of the plastic blade, Fig. 16 is a diagram showing the cross-sectional shape of the plastic finishing blade of each stage on the pitch circle, Fig. 17 is a side perspective view of the plastic finishing blade, and Fig. 18 (a) is a front view of the workpiece. 18 (b) is an enlarged view of the U portion of FIG. 18 (a), FIG. 19 (a) is a diagram showing the work state of the workpiece when it is sequentially cut by the spline blades at each stage, and FIG. 19 (b). FIG. 20 is a side perspective view showing the shape of another plastic finishing blade. FIG. 20 is a diagram showing the machining state of the workpiece when plastic processing is sequentially performed by the plastic finishing blade of each stage.

  The broach 2 shown in FIG. 11 is a tool for machining a tooth groove Wg in which tooth traces are twisted on the inner peripheral surface of the workpiece W by being inserted into a prepared hole Wa previously machined in the workpiece (workpiece) W. (See FIGS. 18A and 18B). The broach 2 includes a front shank portion 60, a cutting blade portion 70, a plastic blade portion 80, and a rear shank portion 90 from the front to the rear.

  As shown in FIG. 11, the front shank part 60 has a front support part 61 provided at the front end thereof, and a front guide part 62 provided at the rear end thereof. The front support 61 is supported by a broaching machine (not shown). The front guide part 62 has a front guide part 62a and a rear guide part 62b. The front guide portion 62a is formed in a tapered shape so that the outer diameter thereof gradually increases from the front to the rear. On the other hand, the rear guide portion 62b is formed continuously from the rear end of the front guide portion 62a, and has an outer diameter that is the same columnar shape as the rear end of the front guide portion 62a. That is, the work W is centered by inserting the rear guide portion 62b into the prepared hole Wa of the work W during processing.

  As shown in FIGS. 11 to 13, the cutting blade portion 70 is provided with a plurality of spline blades 71. The spline blade 71 is provided with Sn stages (n corresponds to the number of stages of the spline blade 71) at equal angular intervals in the circumferential direction on the outer peripheral surface of the shaft portion of the broach 2 (cutting blade portion 70) and at equal intervals in the broach axis direction. It has been. The Sn-stage spline blades 71 arranged in the broach axis direction are formed such that the height gradually increases from the first stage to the Sn stage. That is, the amount of increase in the height from the previous stage becomes the cut amount in the spline blade 71 of each stage.

  As shown in FIGS. 11 and 14 to 17, the plastic blade portion 80 is provided with a plurality of plastic finishing blades 81. The plastic finishing blade 81 has Bn steps (n is the number of steps of the plastic finishing blade 81) at equal angular intervals in the circumferential direction on the outer peripheral surface of the shaft portion of the broach 2 (plastic blade portion 80) and at equal intervals in the broach axis direction. ) Is provided. The Bn-stage plastic finishing blades 81 arranged in the broach axis direction are formed to have the same height, and the tooth thickness gradually increases from the first stage to the Bn stage. It is formed as follows. Furthermore, in each stage of the plastic finishing blade 81, each tooth surface length (land width) is formed to the same length, and each tooth surface is formed by a surface parallel to the tooth surface and the broach axis. An approach angle that is an angle is formed by α.

  Note that at least one of the left and right tooth surfaces of the plastic finishing blade 81 has an approach angle α. In the present embodiment, as shown in FIG. 16, the tooth surface of the plastic finishing blade 81 is formed so as to alternately have an approach angle α every three steps, and the approach angle is also applied to the tooth surface on the opposite side from the third step. α is given. Finally, in the Bn-stage plastic finishing blade 81, an approach angle α is given to the left and right tooth surfaces.

  Here, the Bn-stage plastic finishing blade 81 will be described as a representative of the plastic finishing blades 81 at each stage. As shown in FIG. 17, the Bn-stage plastic finishing blade 81 includes a front inclined surface 81a, an upper inclined surface 81b, a rear vertical surface 81c, left and right approach surfaces 81d, and left and right straight lands 81e. The front inclined surface 81a is inclined so as to become higher toward the rear. The upper inclined surface 81b is inclined so as to become higher from the rear end of the front inclined surface 81a toward the rear. The rear vertical surface 81c is formed so as to be orthogonal to the broach axis. The left and right approach surfaces 81d are formed at the approach angle α. The left and right straight lands 81e are parallel to the broach axis, that is, formed with an approach angle of 0 degree, and constitute a tooth surface that plastically processes the workpiece W together with the approach surface 81d.

  As shown in FIG. 16, when the approach angle α is 0 degree in the plastic finishing blade 81, its tooth surface is formed only by the straight land 81e. That is, plastic working is not performed on the tooth surface formed of the straight land 81e, and the straight land 81e serves as a guide surface.

  As shown in FIG. 11, the rear shank part 90 has a rear guide part 91 provided at the front end thereof, and a rear support part 92 provided at the rear end thereof. The rear guide portion 91 is disposed in the opening of the workpiece W at the end of processing and holds the workpiece W. Further, the rear support portion 92 is supported by a broaching machine (not shown).

  Next, an operation when processing using the broach 2 described above will be described.

  First, as shown in FIG. 18 (a), after forming a pilot hole Wa to the extent that the rear guide portion 62b of the broach 2 can pass through the work W, the work W is placed on the broaching machine. On the other hand, the broach 2 is fixed to the broaching machine via the rear support part 62 so as to face the prepared hole Wa of the workpiece W.

  Next, the broach 2 is passed through the pilot hole Wa while moving the workpiece W toward the broach 2. At this time, since the workpiece W is installed without being fixed on the broaching machine, the front guide portion 62a and the rear guide portion 62b of the front guide portion 62 are sequentially passed through the lower hole Wa of the workpiece W, The workpiece W moves smoothly and is centered.

  Next, the front support 61 of the broach 2 is fixed to the broaching machine with the workpiece W penetrating the broach 2. Then, when the broach 2 is pushed forward while being driven to rotate, the cutting blade portion 70 moves to the prepared hole Wa of the workpiece W and cutting is performed. At this time, as shown in FIG. 19A, the Sn-stage spline blade 71 sequentially passes from the first-stage spline blade 71 to the pilot hole Wa of the workpiece W, and finally the Sn-stage A processed part We having a cross-sectional shape substantially the same as the tooth profile of the spline blade 71 is formed in a spiral shape at equal angular intervals in the circumferential direction of the inner peripheral surface of the workpiece W. In other words, in the cutting blade portion 70, only the cutting process on the workpiece W to the radially outer side of the broach 2 is performed.

  Subsequently, the broach 2 is pushed forward while being driven to rotate, so that the plastic blade 80 moves into the workpiece W and plastic working is performed. At this time, as shown in FIG. 19 (b), the first-stage plastic finishing blade 81 through the Bn-stage plastic finishing blade 81 sequentially pass through the workpiece We of the workpiece W, and the workpiece W The plastic machining allowances Wf on both sides of the processed portion We are sequentially plastic processed. Further, in the plastic finishing blade 81 in which either one of the left and right tooth surfaces is formed only by the straight land 81e, the tooth surface serves as a guide surface, and therefore the broach 2 is rotated to process a twisted tooth groove. Even if it exists, stable plastic working is performed. Then, as shown in FIG. 18B, when the plastic working in the Bn-stage plastic finishing blade 81 is completed, a tooth groove Wg having a predetermined shape is formed in the workpiece W. That is, in the plastic blade portion 80, only plastic working in the circumferential direction of the broach 2 is performed on the workpiece W.

  As shown in FIG. 20, a chamfered relief surface 81f may be formed behind the straight land 81e. Thereby, the strength of the plastic finishing blade 81 is improved, and the straight land 81e is prevented from being damaged.

  Therefore, according to the broach according to the present invention, the workpiece W is formed by cutting the workpiece W radially outward with the spline blade 71 and then the workpiece W is covered with the plastic finishing blade 81. The plastic working allowance Wf of the workpiece W can be reduced by performing plastic working on the processed portion We in the circumferential direction to form the tooth groove Wg on the inner peripheral surface of the workpiece W. As a result, the processing load on the plastic finishing blade 81 is reduced, so that the tool life of the broach 2 can be extended. Moreover, since the strength of the plastic finishing blade 81 is improved by forming the flank 81f at the rear part of the plastic finishing blade 81, the tool life can be further extended.

  In addition, by performing plastic working with the plastic finishing blade 81, compressive stress is applied to the work surface of the workpiece W, so that not only the surface accuracy is improved, but the work surface is hardly formed. Accordingly, when the tooth groove Wg is formed on the inner peripheral surface of the workpiece W as in the present embodiment, the work surface to be plastically processed is the tooth surface of the internal gear. An internal gear having the same can be manufactured.

  The present invention can be applied to broaching that can improve the surface roughness.

1 is a schematic configuration diagram of a broach according to a first embodiment of the present invention. (A) is AA arrow sectional drawing of FIG. 1, (b) is the P section enlarged view of (a). It is a longitudinal cross-sectional view of a cutting blade part. (A) is BB arrow sectional drawing of FIG. 1, (b) is the Q section enlarged view of (a). It is a longitudinal cross-sectional view of a plastic blade part. It is the figure which showed the cross-sectional shape on the pitch circle of the plastic finishing blade of each step | level. It is a side perspective view of a plastic finishing blade. (A) is a workpiece front view, (b) is an enlarged view of the R part of (a). (A) is the figure which showed the processing state of the workpiece | work when it cuts sequentially by the spline blade of each step | paragraph, (b) shows the processing state of the workpiece | work when sequentially plastic-working by the plastic finishing blade of each step | paragraph. It is a figure. It is the side perspective view which showed the shape of the other plastic finishing blade. It is a schematic block diagram of the broach which concerns on 2nd Example of this invention. (A) is CC sectional view taken on the line of FIG. 11, (b) is the S section enlarged view of (a). It is a longitudinal cross-sectional view of a cutting blade part. (A) is DD sectional view taken on the line of FIG. 11, (b) is the T section enlarged view of (a). It is a longitudinal cross-sectional view of a plastic blade part. It is the figure which showed the cross-sectional shape on the pitch circle of the plastic finishing blade of each step | level. It is a side perspective view of a plastic finishing blade. (A) is a workpiece front view, (b) is an enlarged view of the U part of (a). (A) is the figure which showed the processing state of the workpiece | work when it cuts sequentially by the spline blade of each step | paragraph, (b) shows the processing state of the workpiece | work when sequentially plastic-working by the plastic finishing blade of each step | paragraph. It is a figure. It is the side perspective view which showed the shape of the other plastic finishing blade.

Explanation of symbols

1, 2 Broach 10, 60 Front shank part 20, 70 Cutting blade part 30, 80 Plastic blade part 40, 90 Rear shank part 11, 61 Front support part 12, 62 Front guide part 21, 71 Spline blade 31, 81 Plastic Finishing blades 41, 91 Rear guide portions 42, 92 Rear support portions 31a, 81a Front inclined surfaces 31b, 81b Upper inclined surfaces 31c, 81c Rear vertical surfaces 31d, 81d Approach surfaces 31e, 81e Straight lands 31f, 81f Flank W Work Wa Prepared hole Wb, We Work part Wc, Wf Plastic working allowance Wd, Wg Tooth groove α Approach angle

Claims (2)

A plurality of cutting edges that are provided in the axial direction and perform cutting toward the radially outer side of the workpiece;
A plurality of parts are provided in the axial direction behind the cutting edge, and plastic working is performed in a circumferential direction on a work part of the work piece cut by the cutting edge, and the work part is formed into a predetermined groove shape. A broach characterized by having a finishing blade for finishing. The broach according to claim 1, wherein
The broach characterized by forming a flank in the rear part of the said finishing blade.

Images