JP6225671B2 - Brooch cutter - Google Patents

Description

  The present invention relates to a broach cutter for cutting a plurality of internal teeth in a machining hole of a workpiece.

  A broach cutter for cutting internal teeth is formed in a state where a plurality of cutting edge steps having a plurality of cutting edges arranged in the circumferential direction are arranged in the axial direction. The broach cutter is formed such that a plurality of cutting edge stages for rough cutting and a plurality of cutting edge stages for finishing cutting are sequentially arranged in the cutting direction. Then, in rough cutting, the cutting edge is sequentially cut in the radial direction of the machining hole of the workpiece to form an intermediate shape of the internal teeth, and in finish cutting, the cutting blade is sequentially cut in the circumferential direction of the intermediate shape of the internal teeth and the internal teeth Is formed.

  For example, in the internal gear machining broach of Patent Document 1, four types of cutting blades for cutting a plurality of internal teeth from a workpiece are used. And the 1st cutting blade of four types of cutting blades cuts the tooth main-body part of an internal tooth. Moreover, a pair of stepped parts located in the inner peripheral side rather than a tooth main-body part are cut in the state by which the 2nd cutting blade of four types of cutting blades is guided to a tooth-body main part. Moreover, the 3rd cutting blade of 4 types of cutting blades cuts the small diameter part formed between a pair of step part in the state guided to a tooth main-body part. Further, the tooth body portion is further cut so that the fourth cutting blade of the four types of cutting blades widens the width of the tooth body portion. In Patent Document 1, the second cutting edge and the third cutting edge have a shape that guides the tooth main body, thereby preventing a relative positional shift in the radial direction between the broach and the workpiece, and the tooth bottom surface (tooth The concentricity between the outer peripheral side surface of the main body and the small diameter surface (the inner peripheral side surface of the small diameter portion) is improved.

  Moreover, in the conventional broach shown by the background art of patent document 1, the 1st cutting blade which cuts a pair of inner peripheral part of an internal tooth into a workpiece | work, and the 2nd which cuts a pair of outer peripheral part of an internal tooth into a workpiece | work. Cutting blades are alternately formed one by one in the axial direction of the broach. Then, the first cutting edge and the second cutting edge simultaneously cut the workpiece.

JP 2008-22214 A

However, in patent document 1, in order to reduce wear of a cutting blade, the device which reduces the cutting amount of the cutting blade to a workpiece | work is not made | formed.
In patent document 1, each cutting of a tooth main-body part, a pair of step part, a small diameter part, and a pair of outer peripheral part is performed separately by four types of cutting blades. Therefore, in order to arrange the four types of cutting blades separately and independently while maintaining the overall length of the broach, it is necessary to reduce the number of each cutting blade. As a result, the cutting amount per blade of each cutting blade increases, and each cutting blade is easily worn.

  Moreover, in the conventional broach shown by the background art of patent document 1, the 1st cutting blade and the 2nd cutting blade are alternately formed in 1 step | paragraph at the axial direction of a broach. Therefore, in order to arrange | position the 1st cutting blade and the 2nd cutting blade separately separately, maintaining the full length of a broach, it is necessary to reduce the number of each cutting blade. As a result, the cutting amount per cutting blade increases, and each cutting blade is easily worn. Furthermore, when the length (width) in the axial direction of the workpiece to be cut is small, it is difficult to prevent relative displacement between the broach and the workpiece in the radial direction.

  The present invention has been made in view of such a background, and was obtained by providing a broach cutter capable of effectively preventing relative displacement in the radial direction with a workpiece and extending its life. Is.

According to an aspect of the present invention, a workpiece hole is sequentially cut by a plurality of cutting blade steps formed side by side in the axial direction, and is arranged in the circumferential direction by a plurality of cutting blades arranged in the circumferential direction of each of the cutting blade steps. A broach cutter for forming a plurality of internal teeth in the processed hole,
The plurality of cutting blade steps are configured to cut by cutting the cutting positions of the plurality of cutting blades stepwise in the radial direction of the machining hole of the workpiece,
The mixed cutting blade step formed in at least two or more of the plurality of cutting blade steps includes a relief portion forming portion extending from the tooth main body portion to the radially outer peripheral side in the plurality of internal teeth, and the plurality of cutting blade steps. Having a shape that simultaneously cuts the formation part of the inner peripheral side tooth tip portion of the inner teeth of the inner teeth ,
The mixed cutting blade step includes a plurality of pre-mixed cutting blade steps for simultaneously cutting the formation site of both side portions excluding the central portion in the circumferential direction of the inner peripheral tooth tip portion, and the formation portion of the relief portion, A broach cutter comprising a plurality of late mixing cutting edges for cutting a central portion forming portion simultaneously with the relief portion forming portion .

According to another aspect of the present invention, a machining hole of a workpiece is sequentially cut by a plurality of cutting blade steps formed side by side in the axial direction, and the plurality of cutting blades arranged in the circumferential direction of each cutting blade step in the circumferential direction. A broach cutter for forming a plurality of lined internal teeth in the processed hole,
The plurality of cutting blade steps are configured to cut by cutting the cutting positions of the plurality of cutting blades stepwise in the radial direction of the machining hole of the workpiece,
The mixed cutting blade step formed in at least two or more of the plurality of cutting blade steps includes a formation portion of a tooth main body portion in the plurality of internal teeth and an inner peripheral side tooth tip portion in the plurality of internal teeth. The broaching cutter has a shape that simultaneously cuts the forming portion.

  The broach cutter according to the above aspect is a mixture in which at least two or more of the plurality of cutting blade stages simultaneously cut the formation part of the relief part in the internal tooth and the formation part of the inner peripheral side tooth tip part in the internal tooth. It has a cutting edge. Here, the formation site refers to a site in the workpiece. And when the formation site | part of the inner peripheral side tooth tip part in a workpiece | work is cut with the mixing cutting blade, the formation site | part of the escape part in a workpiece | work is cut with the mixing cutting blade simultaneously with this. Thereby, when the formation site of the inner peripheral side tooth tip portion is cut by the mixing cutting blade, the radial misalignment between the broaching cutter and the workpiece is caused by the mixing cutting blade being the formation site of the relief portion. Can be prevented by cutting. In this way, the relative position shift of the broaching cutter and the workpiece in the radial direction can be prevented by each mixing cutting edge stage itself. And in the workpiece | work after cutting, the concentricity of the outer peripheral side surface of an escape part and the inner peripheral side surface of an inner peripheral side tooth tip part can be maintained favorable.

  Moreover, the function of the some 1st cutting edge step which cuts the formation site | part of a relief part, and the function of the some 2nd cutting blade step which cuts the formation site | part of an inner peripheral side tooth tip part are several mixing cutting blades. Can be held in steps. Accordingly, under the condition that the cutting amounts of the plurality of cutting blades are the same, the first cutting blade step and the second cutting blade step are formed in half compared to the axial length of the broach cutter formed separately. A plurality of mixed cutting edge stages can be formed by a broach cutter having a length in the axial direction. Further, when maintaining the axial length of the broach cutter in which the first cutting blade step and the second cutting blade step are separately formed, the mixed cutting blade is used in the broach cutter in which the mixing cutting blade step is formed. The step forming pitch can be halved to double the number of mixed cutting blade steps. And the cutting amount in which the mixed cutting blade in the mixed cutting blade stage cuts the machining hole of the workpiece can be halved.

Therefore, wear generated in the broach cutter can be reduced in accordance with the reduction of the cutting depth. Further, by reducing the formation pitch of the mixed cutting edge steps and increasing the number of mixed cutting blade steps, the number of mixed cutting blade steps that simultaneously cut the workpiece increases. As a result, it is possible to more effectively prevent the relative displacement between the broaching cutter and the workpiece in the radial direction.
In particular, even when a workpiece having a small axial length (width) is cut, two or more mixed cutting blade steps are simultaneously in contact with the workpiece hole. Therefore, it is possible to effectively prevent the radial displacement of the broach cutter and the workpiece, in other words, the radial guidance of the broach cutter relative to the workpiece by the mixed cutting edge step having a small formation pitch. .

  Further, in the broach cutter according to the above aspect, when any one of the plurality of cutting blade stages cuts the formation portion of the tooth body portion in the workpiece, the formation portion of the inner peripheral side tooth tip portion in the workpiece is determined. At the same time, cutting is eliminated or reduced. Therefore, in the cutting of the formation site of the tooth body part, it is possible to reduce the effect of cutting other parts, and the accuracy of cutting the tooth body part can be improved.

In addition, the number of forming stages of the plurality of mixed cutting edges and the cutting amount of each mixed cutting edge can be arbitrarily determined.
Therefore, according to the broach cutter of the above aspect, it is possible to effectively prevent the relative displacement in the radial direction with respect to the workpiece and to extend the life thereof.

Also in the broach cutter of the other aspect, the configuration of the mixed cutting edge stage can prevent the relative displacement in the radial direction between the broach cutter and the workpiece, similarly to the broach cutter of the one aspect.
Moreover, in the broach cutter of the said other aspect, the formation site | part of the inner peripheral side tooth tip part in a workpiece | work is cut simultaneously with the formation site | part of a tooth | gear main-body part in a workpiece | work by a mixing cutting blade step. Therefore, when the formation site | part of the inner peripheral side tooth-tip part is cut, the broach cutter can contact a workpiece | work with the wide contact area by a tooth main-body part. Thereby, in the broach cutter according to the other aspect described above, it is possible to more effectively prevent the relative displacement between the broach cutter and the workpiece in the radial direction and the circumferential direction, and to extend the life thereof. .

FIG. 3 is an explanatory view showing a broach cutter according to the first embodiment. Explanatory drawing which shows the state which the cutting blade in each cutting-blade stage of a broach cutter according to Example 1 cuts the work hole of a workpiece | work deeply in steps, and forms an internal tooth. In the broach cutter concerning Example 1, the explanatory drawing which shows the state by which the early stage mixing cutting edge stage and the latter stage mixing cutting edge stage were formed along with the axial direction. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing (a) an early mixed cutting blade that cuts a work hole of a workpiece and (b) a late mixed cutting blade that cuts a work hole of a work according to Example 1; Example 1 (a) The state of a machining hole of a workpiece that is cut stepwise in the radial direction by the first mixed cutting blade, (b) The workpiece that is stepped in the radial direction by the latter mixed cutting blade. Explanatory drawing which shows the state of the processed hole. Explanatory drawing which shows the late stage mixed cutting edge which cuts with respect to the working hole of Example (a) cutting with respect to the machining hole of a workpiece | work, and (b) cutting with respect to the machining hole of a workpiece | work. Example 2 (a) The state of the machining hole of the workpiece that is stepwise cut in the radial direction by the first mixed cutting blade, (b) The workpiece that is stepped in the radial direction by the latter mixed cutting blade. Explanatory drawing which shows the state of the processed hole.

A preferred embodiment of the above broach cutter will be described.
In the broach cutter according to the one aspect, a plurality of tooth body part cutting blade stages for cutting the tooth body part by gradually deepening cutting positions of the plurality of cutting blades, and cutting of the plurality of cutting blades A plurality of mixed cutting edges for cutting the forming portion of the relief portion and the forming portion of the inner peripheral tooth tip portion simultaneously with the plurality of mixed cutting blades, with the position being deepened stepwise, and the cutting direction You may line up sequentially from the upstream side.

In addition, the mixed cutting blade stage includes a plurality of pre-mixed cutting blade stages for simultaneously cutting the forming portions of both side portions excluding the central portion in the circumferential direction of the inner peripheral tooth tip portion simultaneously with the forming portion of the relief portion. , that have a forming portion of the central portion is constituted by a plurality of late mixing cutting stage for cutting at the same time as the formation sites of the relief portion.
Thereby , the cutting amount of the some mixing cutting blade at the time of cutting the inner peripheral side tooth tip part can be made appropriate.

In the broach cutter according to the other aspect described above, the mixed cutting blade stage is formed on the outer peripheral side of the plurality of inner teeth on the outer peripheral side with respect to the center position in the radial direction of the tooth main body. You may have the shape cut simultaneously with the formation part of a tooth tip part.
In the plurality of cutting edge stages, the cutting of the formation portion of the tooth main body portion in the workpiece is performed prior to the cutting of the formation portion of the inner peripheral tooth tip portion in the workpiece. In addition, the cutting of the formation site of the inner peripheral tooth tip portion can be performed only when the cutting of the formation site of the tooth body portion proceeds to some extent. Therefore, it is preferable that the mixed cutting edge stage has a shape that simultaneously cuts the formation site on the outer peripheral side and the formation site of the inner peripheral side tooth tip part with respect to the radial center position of the tooth body part.

Hereinafter, an embodiment of a broach cutter will be described with reference to the drawings.
Example 1
As shown in FIGS. 1 and 2, the broach cutter 1 of this example sequentially cuts the machining holes 81 of the workpiece 8 by a plurality of cutting blade stages 2, 3, 4 formed side by side in the axial direction L. The broach cutter 1 is used for forming a plurality of internal teeth 82 arranged in the circumferential direction C in the machining hole 81 by the plurality of cutting blades 21, 31, 41 arranged in the circumferential direction C of the respective cutting blade stages 2, 3, 4. Used. The plurality of cutting blade stages 2, 3, 4 are configured to cut the cutting positions of the plurality of cutting blades 21, 31, 41 in a stepwise manner in the radial direction R of the machining hole 81 of the workpiece 8. .
The mixed cutting blade stages 3 and 4 formed in at least two or more of the plurality of cutting blade stages 2, 3 and 4 extend from the tooth body portion 821 of the plurality of internal teeth 82 to the outer peripheral side R <b> 1 in the radial direction R. It has the shape which cuts simultaneously the formation part of escape part 822, and the formation part of inner peripheral side tooth tip part 823 in a plurality of internal teeth 82. FIG. Here, the formation site refers to a site in the workpiece 8.

Hereinafter, the broach cutter 1 of this example will be described in detail with reference to FIGS.
As shown in FIG. 1, the broach cutter 1 of this example is attached to a broaching machine and used for drawing a round hole as a machining hole 81 formed at the center of a disk-shaped workpiece 8. The When performing a drawing process on the machining hole 81 of the workpiece 8, the plurality of cutting edge steps 2, 3, 4 in the broach cutter 1 pass through the machining hole 81 of the workpiece 8.
Shank portions 11 for attaching the broach cutter 1 to the broaching machine are formed at both ends of the broach cutter 1. A guide for guiding the center of the machining hole 81 of the workpiece 8 to the center of the broach cutter 1 at a position adjacent to the downstream side of the shank portion 11 located upstream of the cutting direction (drawing direction) S of the broach cutter 1. Part 12 is formed. In the following description, the upstream side indicates the upstream side in the cutting direction S, and the downstream side indicates the downstream side in the cutting direction S.

As shown in FIGS. 1 and 2, the tooth body 821 of the plurality of internal teeth 82 of the work 8 is placed at a position adjacent to the downstream side of the guide 12 in the broach cutter 1 by the plurality of cutting blades 21. A plurality of tooth body part cutting blade steps 2 for cutting the formation site are formed. The plurality of cutting blades 21 are configured to cut the machining hole 81 of the workpiece 8 deeply stepwise in the radial direction R.
Here, in FIG. 1, in the broach cutter 1, a portion in which a plurality of tooth main body cutting blade steps 2 are formed side by side in the axial direction L is indicated by L <b> 1, and a plurality of premixed cutting blade steps 3 are in the axial direction L A portion formed side by side is indicated by L2, and a portion where a plurality of late mixing cutting edge stages 4 are formed side by side in the axial direction L is indicated by L3. 2 shows a state in which the cutting blades 21, 31, and 41 in the respective cutting blade stages 2, 3, and 4 deeply cut the machining hole 81 of the workpiece 8 stepwise to form the internal teeth 82. .

As shown in FIG. 2, the tooth main body 821 of the internal tooth 82 has tooth surfaces located on both sides in the circumferential direction C. The escape portion 822 is formed on the outer peripheral side R1 in the radial direction R from the tooth body portion 821, and has a width in the circumferential direction C that is narrower than the width in the circumferential direction C of the tooth body portion 821.
FIG. 3 shows a state in which the first mixed cutting blade stage 3 and the latter mixed cutting blade stage 4 are formed side by side in the axial direction L in the broach cutter 1. As shown in the figure, the plurality of early mixing cutting blade stages 3 are formed adjacent to the downstream side of the plurality of tooth main body cutting blade stages 2, and the plurality of latter mixing cutting blade stages 4 include a plurality of It is formed adjacent to the downstream side of the first mixing cutting blade stage 3.

  FIG. 4A shows the first-stage mixed cutting blade 31 for cutting the machining hole 81 of the workpiece 8, and FIG. 4B shows the latter-stage mixing for cutting the machining hole 81 of the workpiece 8. The cutting edge 41 is shown. As shown in the drawing, the plurality of mixed cutting edge stages 3 and 4 are formed such that the formation part of both side parts 825 excluding the central part 824 in the circumferential direction C in the inner peripheral side tooth tip part 823 is defined as the formation part of the relief part 822. A plurality of early mixed cutting blade stages 3 for cutting simultaneously and a plurality of late mixed cutting blade stages 4 for cutting the formation portion of the central portion 824 simultaneously with the formation portion of the relief portion 822 are configured.

FIG. 5A shows a state of the machining hole 81 of the workpiece 8 that is stepwise cut in the radial direction R by the first mixed cutting edge 31, and FIG. The state of the machining hole 81 of the workpiece 8 that is cut in stages in the radial direction R is shown. As shown in the figure, the plurality of the first mixing cutting blade stages 3 and the plurality of the second mixing cutting blade stages 4 deepen the cutting positions in the radial direction R of the plurality of mixing cutting blades 31 and 41 in stages, The mixed cutting blades 31 and 41 simultaneously cut the formation site of the escape portion 822 and the formation site of the inner peripheral tooth tip portion 823.
The inner peripheral side tooth tip portion 823 of the inner tooth 82 is cut by being divided into a plurality of the first mixing blades 31 in the first mixing blade stage 3 and a plurality of the second mixing cutting blades 41 in the second mixing blade stage 4. Thereby, the cutting amount which cuts the inner peripheral side tooth tip part 823 can be made appropriate.

  As shown to Fig.4 (a), the several pre-mixing cutting blade 31 in the pre-mixing cutting blade stage 3 is a pair of inner peripheral side for cutting the formation site | part of the both-sides part 825 in the inner peripheral side tooth tip part 823. As shown in FIG. It has a cutting edge portion 311 and an outer peripheral side cutting edge portion 312 for cutting a portion where the relief portion 822 is formed. The tip corners 311A located on the left and right sides of the pair of inner peripheral cutting edge portions 311 and the pair of tip corners 312A of the outer peripheral cutting edge portions 312 reduce wear of the tip corners 311A and 312A. Therefore, a curved surface shape is formed.

As shown in FIG. 4B, the plurality of late mixing cutting edges 41 in the late mixing cutting edge stage 4 are a pair of inner peripheral sides for cutting the formation site of the central portion 824 in the inner peripheral tooth tip portion 823. It has a cutting edge part 411 and an outer peripheral side cutting edge part 412 for cutting the formation site of the relief part 822. The pair of tip corner portions 412A of the outer peripheral side cutting edge portion 412 is formed with a curved surface shape for reducing wear of the tip corner portions 411A and 412A.
Further, the inner peripheral cutting edge portion 411 of the plurality of late mixing cutting blades 41 in the latter mixing cutting blade stage 4 does not cut the entire formation site of the central portion 824 in the inner peripheral tooth tip portion 823. And this center part 824 protrudes from the both-sides part 825 in the inner peripheral side tooth tip part 823 after cutting by the inner peripheral side cutting edge part 411 of the plurality of late mixing cutting edges 41 in the latter stage mixing cutting edge stage 4. Left behind.

As shown in FIG. 2, the plurality of tooth body part cutting blade steps 2, the plurality of first mixing blade steps 3, and the plurality of latter mixing cutting blade steps 4 are sequentially cut in the radial direction R of the machining hole 81 of the workpiece 8. It is a cutting edge step for rough cutting that cuts the intermediate shape of the internal teeth 82.
As shown in FIG. 1, the circumferential direction of the intermediate shape of the internal teeth 82 of the machining hole 81 of the workpiece 8 is provided as a cutting edge step for finishing cutting at a position adjacent to the downstream side of the plurality of late mixing cutting blade steps 4. A plurality of shell cutting edge steps 5 that are deeply cut into C are formed. The plurality of shell cutting blade stages 5 are formed in a row in the axial direction L of the broach cutter 1 and have a plurality of cutting blades 51 arranged in the circumferential direction C. As shown in FIG. 2, the shape of the pair of tooth surfaces of the tooth main body portion 821 in the internal tooth 82 is formed by the plurality of cutting blades 51 in the plurality of shell cutting blade stages 5. In addition, another guide portion for guiding the center of the machining hole 81 of the workpiece 8 to the center of the broach cutter 1 may be formed at a position adjacent to the downstream side of the shell cutting edge step 5.

  The broach cutter 1 of this example forms a plurality of involute spline-shaped internal teeth 82 having a tooth body 821 along an involute curve in the circumferential direction C. Further, the internal teeth 82 to be cut by the broach cutter 1 have a helical shape in which the tooth main body portion 821 is twisted with respect to the axial direction L of the workpiece 8. The broach cutter 1 forms 82 internal teeth as a helical gear.

  The broach cutter 1 can also be formed with a plurality of rectangular spline-shaped internal teeth 82 in the circumferential direction C having tooth main body portions 821 parallel to each other. Further, the plurality of cutting blades 21, 31, 41, 51 of each cutting blade step 2, 3, 4, 5 in the broach cutter 1 may be formed at equal intervals on the entire circumference in the circumferential direction C. Further, the plurality of cutting blades 21, 31, 41, 51 of each of the cutting blade stages 2, 3, 4, 5 may not be formed on the entire circumference in the circumferential direction C, for example, 2 to 2 in the circumferential direction C. You may form in eight places.

Next, the effect of the broach cutter 1 of this example is demonstrated.
In the broach cutter 1 of the present example, a plurality of early mixed cutting blade stages 3 and a plurality of late mixed cutting blade stages 4 are arranged in the cutting direction S downstream of the cutting direction S of the plurality of tooth body part cutting blade stages 2. Are formed in order from the upstream side. And when the formation site | part of the both-sides part 825 in the inner peripheral side tooth-tip part 823 is cut by the inner peripheral side cutting blade part 311 of each pre-mixing cutting blade 31 in the several pre-mixing cutting blade step 3, it is simultaneous with this. The part where the escape portion 822 is formed is cut by the outer peripheral side cutting edge portion 312 of each of the previous mixing blades 31 in the plurality of the previous mixing cutting blade stages 3.

  Thereby, the radial direction of the broach cutter 1 and the workpiece | work 8 when the formation site | part of the both-sides part 825 in the inner peripheral side tooth tip part 823 is cut by the inner peripheral side cutting edge part 311 of each pre-mixing cutting edge 31. Relative displacement to R can be prevented by forming the outer peripheral side cutting edge portion 311 of each of the previous mixing cutting edges 31 by cutting the relief portion 822. In this way, relative positional displacement in the radial direction R between the broach cutter 1 and the workpiece 8 can be prevented by the plurality of the first mixing blades 31 themselves in each first mixing blade stage 3. And in the workpiece | work 8 after cutting, the concentricity with the outer peripheral side surface of the escape part 822 and the inner peripheral side surface of the both-sides part 825 in the inner peripheral side tooth tip part 823 can be maintained favorable.

  Moreover, when the formation part of the center part 824 in the inner peripheral side tooth tip part 823 is cut by the inner peripheral side cutting edge part 411 of each late mixing cutting edge 41 in the plurality of late mixing cutting edge stages 4, simultaneously with this. The part where the escape portion 822 is formed is cut by the outer peripheral side cutting edge portion 412 of each late mixing cutting edge 41 in the plurality of late mixing cutting edge stages 4. Thereby, the radial direction of the broach cutter 1 and the workpiece | work 8 when the formation site | part of the center part 824 in the inner peripheral side tooth tip part 823 is cut by the inner peripheral side cutting edge part 411 of each late stage mixing cutting edge 41. Relative displacement to R can be prevented by forming the outer peripheral side cutting edge portion 412 of each late mixing cutting edge 41 by cutting the relief portion 822. In this manner, the plurality of late mixed cutting edges 41 themselves in each late mixed cutting edge stage 4 can prevent the relative displacement between the broaching cutter 1 and the workpiece 8 in the radial direction R. And in the workpiece | work 8 after cutting, the concentricity with the outer peripheral side surface of the escape part 822 and the inner peripheral side surface of the center part 824 in the inner peripheral side tooth tip part 823 can be maintained favorable.

  Further, in the workpiece 8 after cutting, the entire concentricity of the tooth main body portion 821, the relief portion 822, and the inner peripheral tooth tip portion 823 is favorably maintained. Thereby, the meshing length of the gear constituted by the workpiece 8 does not change, and vibration and noise generated in the gear can be reduced. Moreover, it can prevent that the rotational balance of the gear rotating on the tooth surface basis deteriorates. Furthermore, the inner peripheral side tooth tip part is often used as a processing standard in a post-process after broaching, and the accuracy of this processing standard can be maintained well.

  Moreover, in the broach cutter 1 of this example, the function of the some 1st cutting blade step which cuts the formation site | part of the relief part 822, and the some 2nd cutting blade which cuts the formation site | part of the inner peripheral side tooth tip part 823. The function of the step can be imparted to each of the mixed cutting blade steps 3 and 4. Accordingly, under the condition that the cutting amounts of the plurality of cutting blades are the same, the length in the axial direction L of the broach cutter in which the first cutting blade step and the second cutting blade step are separately formed is compared. The mixed cutting blade stages 3 and 4 can be formed by the broach cutter 1 having a length in the half axial direction L.

  When maintaining the length in the axial direction L of the broach cutter in which the first cutting blade step and the second cutting blade step are separately formed, the broach cutter in which the mixed cutting blade steps 3 and 4 are formed. In 1, the formation pitch of each mixing cutting edge step 3, 4 can be halved, and the number of mixing cutting blade steps 3, 4 can be doubled. Then, the amount of cutting by which each of the mixed cutting blades 31 and 41 in each of the mixed cutting blade stages 3 and 4 cuts the machining hole 81 of the workpiece 8 can be halved.

  As a result, the wear generated in the broach cutter 1 can be reduced in accordance with the reduction of the cutting depth. Further, by reducing the formation pitch of the mixed cutting blade stages 3 and 4 and increasing the number of the mixed cutting blade stages 3 and 4, the mixing cutting blade stages 3 and 4 that simultaneously cut the workpiece 8 are provided. The number of stages increases. As a result, it is possible to more effectively prevent the relative displacement between the broaching cutter 1 and the workpiece 8 in the radial direction R.

  In particular, when cutting the workpiece 8 having a small length (width) in the axial direction L, the two or more mixed cutting blade steps 3 and 4 are simultaneously in contact with the machining hole 81 of the workpiece 8. Therefore, the mixed cutting blade stages 3 and 4 having a small formation pitch prevent the relative displacement between the broaching cutter 1 and the workpiece 8 in the radial direction R, in other words, in the radial direction R of the broaching cutter 1 with respect to the workpiece 8. Guidance can be performed effectively.

  Moreover, in the broach cutter 1 of this example, when the tooth main body part cutting blade stage 2 cuts the formation part of the tooth main body part 821 in the work 8, the formation part of the inner peripheral side tooth top part 823 in the work 8. Almost no cutting at the same time. Therefore, in the cutting of the formation part of the tooth body part 821 by the tooth body part cutting blade stage 2, it is possible to reduce the influence caused by cutting other formation parts and to improve the accuracy of cutting the tooth body part 821. be able to.

In addition, the number of forming stages of the plurality of mixed cutting blade stages 3 and 4 and the cutting amounts of the mixed cutting blades 31 and 41 can be arbitrarily determined.
Therefore, according to the broach cutter 1 of the present example, it is possible to effectively prevent the relative displacement of the workpiece 8 in the radial direction R and to extend the life thereof.

(Example 2)
In this example, as shown in FIGS. 6 and 7, the mixed cutting blade stages 2 </ b> A and 2 </ b> B formed in at least two or more of the plurality of tooth main body cutting blade stages 2 have teeth in the plurality of internal teeth 82. A case where the forming part of the main body part 821 and the forming part of the inner peripheral side tooth tip part 823 in the plurality of internal teeth 82 are cut simultaneously will be described.
The plurality of mixed cutting edge steps 2A and 2B of the present example are formed on the outer peripheral side of the radial position R of the tooth main body portion 821 in the plurality of internal teeth 82 and the inner peripheral side teeth in the plurality of internal teeth 82. The formation part of the front part 823 is cut simultaneously. In addition, the plurality of mixed cutting blade steps 2A and 2B are formed in a rear-side portion of the tooth body cutting blade step 2.

  The plurality of mixed cutting edge stages 2A and 2B are a plurality of parts for cutting the forming portions of both side portions 825 except the central portion 824 in the circumferential direction C in the inner peripheral tooth tip portion 823 simultaneously with the forming portion of the tooth main body portion 821. 2A, and a plurality of late mixed cutting blade steps 2B for cutting the formation part of the central portion 824 simultaneously with the formation part of the tooth body 821. In the broach cutter 1, the plurality of late mixing cutting edge stages 2B are formed adjacent to the downstream side in the cutting direction S of the plurality of early mixing cutting edge stages 2A.

  FIG. 6A shows the early mixing cutting edge 2A for cutting the machining hole 81 of the workpiece 8, and FIG. 6B shows the latter mixing for cutting the machining hole 81 of the workpiece 8. The cutting blade 2B is shown. As shown to Fig.6 (a), the several pre-mixing cutting blade 21A in the pre-mixing cutting blade stage 2A is a pair of inner peripheral side for cutting the formation part of the both-sides part 825 in the inner peripheral side tooth tip part 823. As shown in FIG. It has a cutting blade portion 211A and an outer peripheral cutting blade portion 212A for cutting a formation site of the tooth main body portion 821. As shown in FIG. 6 (b), the plurality of late mixing cutting edges 21B in the latter mixing cutting blade stage 2B are a pair of inner peripheral sides for cutting the formation site of the central portion 824 in the inner peripheral tooth tip portion 823. It has a cutting blade portion 211B and an outer peripheral cutting blade portion 212B for cutting a site where the tooth main body portion 821 is formed.

  FIG. 7A shows the state of the machining hole 81 of the workpiece 8 that is stepwise cut in the radial direction R by the first mixing cutting edge 21A, and FIG. 7B shows the second mixing cutting edge 21B. The state of the machining hole 81 of the workpiece 8 that is cut in stages in the radial direction R is shown. As shown in the figure, the plurality of first mixing cutting blade stages 2A and the plurality of latter mixing cutting blade stages 2B deepen the cutting position in the radial direction R of each of the plurality of mixing cutting blades 21A, 21B stepwise. The mixing cutting blades 21A and 21B simultaneously cut the formation site of the tooth main body portion 821 and the formation site of the inner peripheral tooth tip portion 823.

In the broach cutter 1 of this example, the formation part of the inner peripheral side tooth tip part 823 in the work 8 is cut simultaneously with the formation part of the tooth main body part 821 in the work 8 by the mixed cutting blade steps 2A and 2B. The Therefore, when the formation site of the inner peripheral side tooth tip portion 823 is cut, the broach cutter 1 can contact the workpiece 8 with a wide contact area by the tooth body portion 821. Thereby, in the broach cutter 1 of this example, the relative position shift of the broach cutter 1 and the workpiece | work 8 to the radial direction R and the circumferential direction C can be prevented more effectively, and the lifetime is extended. be able to.
Also in this example, other configurations and reference numerals (not shown) are the same as those in the first embodiment, and the same effects as those in the first embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 Broach cutter 3,4 Mixed cutting blade stage 31,41 Mixed cutting blade 311,411 Inner peripheral side cutting blade part 312,412 Outer peripheral side cutting edge part 8 Workpiece 81 Machining hole 82 Internal tooth 821 Tooth body part 822 Escape part 823 In Peripheral tooth tip S Cutting direction

Claims (1)

A plurality of cutting blade steps formed side by side in the axial direction sequentially cut a machining hole of the workpiece, and a plurality of cutting blades arranged in the circumferential direction of each cutting blade step to process a plurality of internal teeth arranged in the circumferential direction. A broach cutter for forming in a hole,
The plurality of cutting blade steps are configured to cut by cutting the cutting positions of the plurality of cutting blades stepwise in the radial direction of the machining hole of the workpiece,
The mixed cutting blade step formed in at least two or more of the plurality of cutting blade steps includes a relief portion forming portion extending from the tooth main body portion to the radially outer peripheral side in the plurality of internal teeth, and the plurality of cutting blade steps. Having a shape that simultaneously cuts the formation part of the inner peripheral side tooth tip portion of the inner teeth of the inner teeth ,
The mixed cutting blade step includes a plurality of pre-mixed cutting blade steps for simultaneously cutting the formation site of both side portions excluding the central portion in the circumferential direction of the inner peripheral tooth tip portion, and the formation portion of the relief portion, A broach cutter comprising a plurality of late mixing cutting blade steps for cutting a central portion forming portion simultaneously with the relief portion forming portion .

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