JP2007210058A - Shaving cutter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shaving cutter, improving the strength of a gear by eliminating a shaving step to the utmost. <P>SOLUTION: In this shaving cutter, the outline of a tip part 5 of each gear 2 of the shaving cutter is formed in a shape approximate to a curve of the bottom of a gear to be worked, and the length L of a tooth depth is set to a length such that the tip of the tip part 5 reaches the bottom of the gear to be worked. When the roughened gear to be worked is shaved by this shaving cutter, it is machined so that the tooth flank of the gear to be worked and the bottom are smoothly connected, whereby a shaving step is eliminated to improve the strength of the gear. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a shaving cutter used for finishing gears.

In general, gears used in automobile transmissions or the like have a tooth surface finished with high accuracy by shaving after roughing a rough material by hobbing.
Therefore, as shown in FIG. 10, in the conventional shaving cutter 50 used for shaving, a plurality of teeth 51 are formed at predetermined intervals on the outer peripheral portion of the cutter body formed in a disc shape. Yes. Each tooth 51 of the shaving cutter 50 is formed with serration grooves 3 and 3 on the tooth surfaces 52 and 52 on both sides in the width direction at intervals along the tooth line direction. And a cutting edge is formed at the ridge between each serration groove 3 (see FIG. 1).
Then, as shown in FIGS. 10 and 11, the shaving cutter 50 mounted on the main shaft of the shoeing machine and the work gear 20 supported on the rotatable shaft are set at a predetermined crossing angle. The shaving cutter 50 is driven to rotate, and the work gear 20 is driven to rotate. As a result, the tooth surface 52 of each tooth 51 of the shaving cutter 50 and the tooth surface 25 of each tooth 21 of the cutting gear 20 in the direction of the streak caused by the axis crossing angle between the shaving cutter 50 and the cutting gear 20 are obtained. The tooth surface 25 of each tooth 21 of the work gear 20 is shaved by the relative sliding motion.

Further, as shown in FIGS. 10 and 11, the length L1 of the tooth of each tooth 51 of the conventional shaving cutter 50 can cut the range L2 of the tooth surface 22 required for each tooth 21 of the work gear 20. Is set to a length. Furthermore, the tip surface 53 of each tooth 51 of the shaving cutter 50 is formed in a substantially linear shape (more precisely, a part of the arc of the shaving cutter 50). That is, in the conventional shaving cutter 50, when each tooth 51 of the shaving cutter 50 is ground, after the tooth surface 52 of each tooth 51 is ground, the tip surface 53 of each tooth 51 is ground by the cylindrical grinder. Therefore, the tooth tip surface 53 of each tooth 51 is formed in a substantially linear shape.
When the tooth surface 25 of each tooth 21 of the work gear 20 is machined by the conventional shaving cutter 50, as shown in FIG. 11, the tooth surface 52 and the tooth tip surface 53 of each tooth 21 of the shaving cutter 50, Are processed so that the boundary portion between the tooth surface 25 and the tooth bottom portion 23 of the work gear 20 during rough machining is formed by the corner portion 54 between the tooth surface 22 after shaving and the tooth during rough machining. A step (hereinafter referred to as a shaving step) 30 is formed between the bottom portion 23 and the bottom portion 23. If such a shaving step 30 is formed, the strength of the gear 20 is reduced, and when the gear 20 is operated at a high load, the gear 20 may break from the shaving step 30 as a starting point.
In addition, in FIG. 11, the tooth surface of each tooth 21 of the work gear 20 is the tooth surface 25 at the time of rough machining, and the position shown by the solid line is the tooth surface 22 after shaving. . Further, in FIG. 11, the positions indicated by a plurality of arrows indicate the cutting points at each cutting stage.

Therefore, as a method for reducing the shaving level difference, when roughing each tooth 21 of the work gear 20, rough machining is performed using a hob 60 with a pre-shaving prochu balance (hereinafter referred to as a hob with PP) shown in FIG. Then, the method of processing with the conventional shaving cutter 50 is employ | adopted after that.
That is, as shown in FIG. 12, this PP-attached hob 60 is formed with convex portions 62 and 62 projecting in the width direction of the screw portion 61 (left and right direction in the drawing) at the tip of the screw portion 61, respectively. When the work gear 10 is roughly machined by the PP-equipped hob 60, as shown in FIG. 13, the boundary portion between the tooth bottom 23 and the tooth surface 25 of the work gear 20 is recessed 26, and thereafter, If the tooth surface 25 is processed with the shaving cutter 50, the shaving level difference is reduced. However, in this method, if the shaving allowance of both tooth surfaces 22 of the work gear 20 becomes non-uniform, there is a possibility that a shaving step 30 is formed.

Further, Patent Document 1 discloses a shaving cutter in which each slit is formed in each tooth so as to open in the top of each tooth and come out in the direction of the streak.
JP 2005-205506 A

  However, in the shaving cutter of the invention of Patent Document 1, when the shaving cutter is cut, each tooth bends so as to narrow the slit, so that the tooth surface of each tooth of the work gear is each of the shaving cutter. Although it is possible to obtain a highly accurate gear without being crushed by the tooth surface, it is impossible to eliminate the above-described shaving step.

  This invention is made | formed in view of this point, and it aims at providing the shaving cutter which can improve the intensity | strength of a gearwheel by eliminating shaving level | step difference as much as possible.

As a means for solving the above-mentioned problems, the present invention provides a shaving cutter according to claim 1, wherein the outer shape of the tooth tip part is formed in a shape approximating the curve of the tooth bottom part of the work gear. The length of the bamboo is provided with a plurality of teeth set such that the tip of the tooth tip part can reach the tooth bottom part of the work gear.
The invention of the shaving cutter described in claim 2 is characterized in that, in the invention described in claim 1, the outer shape of the tooth tip portion is formed in a curved shape.
The invention of the shaving cutter described in claim 3 is characterized in that, in the invention described in claim 1, the outer shape of the tooth tip portion is formed in a shape connecting a plurality of straight lines having different inclinations. is there.

Therefore, in the invention of the shaving cutter according to claim 1, the shape of the tooth tip portion of each tooth is formed in a shape approximating the curve of the tooth bottom portion of the work gear, and the length of the tooth is the tip of the tooth tip portion. Is set to a length that can reach the tooth bottom portion of the work gear, and is processed by the tooth surface of the tooth tip portion so that the boundary portion between the tooth surface and the tooth bottom portion of the work gear smoothly continues. Therefore, even if a shaving step occurs without forming a shaving step as much as possible, this step becomes a step having a larger curvature than in the prior art.
In the invention of the shaving cutter according to claim 2, the boundary portion between the tooth surface and the tooth bottom portion of the work gear is processed smoothly by the curved tooth surface forming the outer shape of the tooth tip portion. So there is no shaving step.
In the invention of the shaving cutter described in claim 3, the boundary portion between the tooth surface and the tooth bottom portion of the work gear is formed by the tooth surface having a shape in which a plurality of straight lines having different inclinations forming the outer shape of the tooth tip portion are connected. Since it is processed into a curved shape having a larger curvature than the conventional one, even if a shaving step is generated, the step has a larger curvature than the conventional one.

  ADVANTAGE OF THE INVENTION According to this invention, the shaving cutter which can eliminate the shaving level | step difference as much as possible and can improve the intensity | strength of a gearwheel can be provided.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to FIGS.
As shown in FIGS. 1 and 2, the shaving cutter 1 according to the embodiment of the present invention is formed in a plurality of teeth 2 at predetermined intervals in the circumferential direction on the outer peripheral portion of the cutter body 1a formed in a disc shape. Has been. Each tooth 2 is formed with serration grooves 3 and 3 on the tooth surfaces 4 and 4 on both sides in the width direction at intervals along the tooth line direction, and each tooth surface 4 and each serration groove 3 of each tooth 2. A cutting blade is formed at the ridge between the two. Further, the outer shape of the tooth tip portion 5 of each tooth 2 is formed in a shape approximating the curve of the tooth bottom portion 23 of the work gear 20. Further, the length L of each tooth 2 is set such that the tip of the tooth tip 5 can reach the tooth bottom 23 of the work gear 20.

And each tooth | gear 2 of the shaving cutter 1 which concerns on embodiment of this invention comes to be comprised with the 4 form demonstrated below.
First, as shown in FIG. 2, each tooth 2 of the shaving cutter 1 according to the first embodiment has a tooth length L of each tooth 2 and the tip of the tooth tip portion 5 is a tooth of the work gear 20. The bottom 23 is set to a length that allows shaving with a predetermined cutting depth (about 30 μm). Moreover, the external shape of the tip part 5 of each tooth 2 of the shaving cutter 1 is continuous from each tooth surface 4, 4 of the tooth 2 so as to approximate the curve of the tooth bottom part 23 of the work gear 20, and has a predetermined curvature. It is formed in an arc shape having a radius R1.
Then, when the roughing machined gear 20 is shaved by the shaving cutter 1 according to the first embodiment, as shown in FIG. 3, the tooth surface 4 and the tooth tip portion 5 of the tooth 2 of the shaving cutter 1. Thus, the tooth surface 25 and the tooth bottom portion 23 at the time of rough machining of the work gear 20 are cut to a predetermined depth (about 30 μm). As a result, as shown in FIG. 4, a conventionally formed shoeing step 30 (see FIG. 11) is formed at the boundary portion between the tooth surface 22 and the tooth bottom portion 27 of the work gear 20 after shaving. There is nothing to do.
3 and 4, the tooth surface of each tooth 21 of the work gear 20 is a tooth surface 25 at the time of rough machining at a position indicated by a two-dot chain line, and a tooth surface 22 at a solid line is a position indicated by a solid line. In addition, in the tooth bottom portion of each tooth 21, the position indicated by a two-dot chain line is the tooth bottom portion 23 at the time of rough machining, and the position indicated by the solid line is the tooth bottom portion 27 after shaving. Further, in FIG. 3, positions indicated by a plurality of arrows indicate cutting points at each cutting stage.

Next, as shown in FIG. 5, each tooth 2 a of the shaving cutter 1 according to the second embodiment has a length L of each tooth 2 a and a tip of the tooth tip portion 5 of the work gear 20. The length is set so as to reach the tooth bottom 23. Further, the outer radius of the tip portion 5 of each tooth 2a of the shaving cutter 1 is different from the curvature radius R2 from each tooth surface 4, 4 of the tooth 2a so as to approximate the curve of the tooth bottom portion 23 of the work gear 20. It is formed in a shape in which a plurality of continuous curves in R3 are connected.
Then, when the roughing machined gear 20 is shaved by the shaving cutter 1 according to the second embodiment, as shown in FIG. 6, the tooth tip 5 of the tooth 2a of the shaving cutter 1 cuts the workpiece. The boundary portion between the tooth surface 25 and the tooth bottom 23 of the gear 20 during rough machining is machined so that the tooth surface 22 after shaving and the tooth bottom 23 during rough machining are smoothly continuous. As a result, similarly to the shaving cutter 1 according to the first embodiment, a shoe that has been conventionally formed at the boundary between the tooth surface 22 of the work gear 20 after shaving and the tooth bottom 23 at the time of rough machining. Bing step 30 (see FIG. 11) is not formed.

Next, as shown in FIG. 7, each tooth 2 b of the shaving cutter 1 according to the third embodiment has a tooth length L of each tooth 2 b and a tooth tip surface 6 at the tip of the tooth tip portion 5. The length is set so as to reach the tooth bottom 23 of the work gear 20. Further, the outer shape of the tooth tip portion 5 of each tooth 2b of the shaving cutter 1 is approximated to the curve of the tooth bottom portion 23 of the work gear 20, and each of the tooth tip surface 6 and each tooth 2b of the tooth 2b is substantially straight. The substantially linear tooth surfaces 7 and 7 that incline from the tooth surfaces 4 and 4 toward the tooth tip surface 6 are formed in a continuous shape.
Then, when the roughing work gear 20 is shaved by the shaving cutter 1 according to the third embodiment, as shown in FIG. 9, the tooth tip portion 5 of the tooth 2 of the shaving cutter 1 cuts the work. The boundary portion between the tooth surface 25 and the tooth bottom portion 23 at the time of rough machining of the gear 20 is processed into a curved shape having a larger curvature than the conventional one, and between the tooth surface 22 after shaving and the tooth bottom portion 23 at the time of rough machining. Although a slight shaving step 30a is formed, this shaving step 30a is a step having a larger curvature than the conventional shaving step 30 (see FIG. 11).
In addition, the inclination angle with respect to each tooth surface 4, 4 of each tooth surface 7, 7 provided on the tooth tip portion 5 of the tooth 2b according to the third embodiment has a sufficiently large curvature of the curve forming the shaving step 30a. Is set to such an inclination angle. Further, the tooth surfaces 4 and 4 of the tooth 2b and the tooth surfaces 7 and 7 of the tooth tip portion 5 may be connected in a curved manner.
Here, in FIG. 9, the tooth surface of each tooth 21 of the work gear 20 is a tooth surface 25 at the time of rough machining at a position indicated by a two-dot chain line, and a tooth surface 22 after shaving processing at a position indicated by a solid line. is there.

Next, as shown in FIG. 8, each tooth 2 c of the shaving cutter 1 according to the fourth embodiment has a length L of each tooth 2 c and a tip of the tooth tip portion 5 of the work gear 20. The length is set so as to reach the tooth bottom 23. In addition, the outline of the tooth tip portion 5 of each tooth 2c of the shaving cutter 1 is substantially straight from the tooth surfaces 4 and 4 of the tooth 2c so as to approximate the curve of the tooth bottom portion 23 of the work gear 20. It forms in the shape which inclines so that the surfaces 8 and 8 may be connected by the front-end | tip.
Then, when the roughing work gear 20 is shaved by the shaving cutter 1 according to the fourth embodiment, as shown in FIG. 9, the tooth tip portion 5 of the tooth 2 of the shaving cutter 1 cuts the work. The boundary portion between the tooth surface 25 and the tooth bottom portion 23 at the time of rough machining of the gear 20 is processed into a curved shape having a larger curvature than the conventional one, and between the tooth surface 22 after shaving and the tooth bottom portion 23 at the time of rough machining. Although a slight shaving step 30a is formed, this shaving step 30a is a step having a larger curvature than the conventional shaving step 30 (see FIG. 11).
The inclination angle of each tooth surface 8, 8 provided on the tooth tip 5 of the tooth 2c according to the fourth embodiment with respect to each tooth surface 4, 4 has a sufficiently large curvature of the curve forming the shaving step 30a. Is set to such an inclination angle.

As described above, in the shaving cutter 1 according to the embodiment of the present invention, the outer shape of the tooth tip portion 5 of each tooth 2 is formed in a shape approximating the curve of the tooth bottom portion 23 of the work gear 20, The length L of the toothpaste is set to a length L at which the tip of the tooth tip 5 can reach the tooth bottom 23 of the work gear 20. As a result, the meshing rate between the shaving cutter 1 and the work gear 20 is improved, and the tooth surface 22 and the tooth bottom 23 or 27 of the work gear 20 are processed smoothly by the shaving cutter 1. Therefore, the shaving step 30 that has been conventionally formed can be eliminated, and the strength of the gear 20 can be improved. Even if the shaving step 30 a is formed by the present shaving cutter 1, the shaving step 30 a has a larger curvature than the curvature of the conventional shaving step 30, so that it is difficult to be a starting point of breakage of the gear 20. Become.
In addition, grinding of the teeth 2, 2a, 2b, 2c according to the first to fourth embodiments of the shaving cutter 1 is performed using an NC profile grinder instead of the conventionally used shaving cutter grinder and cylindrical grinder. If it is used, grinding becomes possible.

FIG. 1 is a perspective view of each tooth of the shaving cutter according to the embodiment of the present invention. FIG. 2A is a front view of each tooth of the shaving cutter according to the first embodiment of the present invention, and FIG. 2B is an enlarged view of a tooth tip portion. FIG. 3 is a diagram showing in a stepwise manner the process of machining the gear to be cut by the shaving cutter of FIG. FIG. 4 is a front view of each tooth of the work gear after being cut by the shaving cutter of FIG. FIG. 5A is a front view of each tooth of the shaving cutter according to the second embodiment of the present invention, and FIG. 5B is an enlarged view of the tooth tip portion. FIG. 6 is a front view of each tooth of the work gear after being cut by the shaving cutter of FIG. FIG. 7A is a front view of each tooth of the shaving cutter according to the third embodiment of the present invention, and FIG. 7B is an enlarged view of the tooth tip portion. FIG. 8A is a front view of each tooth of the shaving cutter according to the fourth embodiment of the present invention, and FIG. 8B is an enlarged view of the tooth tip portion. FIG. 9 is a front view of each tooth of the gear to be cut after cutting by the shaving cutter of FIGS. 7 and 8. FIG. 10 is a front view of each tooth of a conventional shaving cutter. FIG. 11 is a diagram showing in a stepwise manner the process of machining the work gear with the shaving cutter of FIG. FIG. 12 is a diagram for explaining a conventional gear machining method, and is a front view of each thread portion of a PP-attached hob used when roughing a gear. FIG. 13 is a front view of each tooth of the gear to be cut after being roughly machined by the hob with PP of FIG. 12 and then machined by the conventional shaving cutter shown in FIG.

Explanation of symbols

1 Shaving cutter, 2, 2a, 2b, 2c Teeth, 4, 7, 8 Tooth surface, 5 Tooth tip, 6 Tooth tip, 20 Work gear, 23 Tooth bottom

Claims (3)

  The outer shape of the tooth tip portion is formed in a shape that approximates the curve of the tooth bottom portion of the work gear, and the length of the tooth is such that the tip of the tooth tip portion can reach the tooth bottom portion of the work gear. A shaving cutter comprising a plurality of teeth set to.   The shaving cutter according to claim 1, wherein an outer shape of the tooth tip portion is formed in a curved shape. 2. The shaving cutter according to claim 1, wherein an outer shape of the tooth tip portion is formed in a shape in which a plurality of straight lines having different inclinations are connected.

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