JP6957908B2 - Manufacturing method of electrodes and dies for electric discharge machining - Google Patents

Description

The present invention relates to a method for manufacturing an electrode for electric discharge machining and a mold.

Patent Document 1 discloses a technique for manufacturing a die used for forging a helical gear by die-sinking electric discharge machining. Here, an example of a method of manufacturing the mold 10 by the conventional die-sinking electric discharge machining will be described with reference to the drawings.

As shown in FIGS. 1 and 2, the die 10 is used when the pinion gear 100 is manufactured by forging. The pinion gear 100 is a member attached to the tip of the steering shaft, meshes with the rack, and converts the rotary motion input from the steering wheel into a linear motion.

As shown in FIG. 1, the pinion gear 100 includes a gear portion 101, a shaft portion 102, and a diameter-expanded portion 103. The gear portion 101 is a portion that meshes with the rack, and a plurality of spirally extending tooth portions and groove portions are formed on the outer peripheral surface of the gear portion 101. The shaft portion 102 is a columnar portion formed coaxially with the gear portion 101. The diameter-expanded portion 103 is a portion continuous with the gear portion 101 and the shaft portion 102, and is formed so that the outer diameter increases from the gear portion 101 side to the shaft portion 102 side. Further, on the outer peripheral surface of the enlarged diameter portion 103, an introduction gear portion 103a which is an incomplete tooth and a groove continuously formed in the tooth portion and the groove portion of the gear portion 101 is formed at the connection portion with the gear portion 101. Will be done.

As shown in FIG. 2, the mold 10 includes a land portion 11, a guide portion 12, and a land relief portion 13. The land portion 11 is formed by squeezing a plurality of tooth portions and grooves on the outer peripheral surface of the shaft-shaped material S100 by passing the shaft-shaped material S100 in the axial direction. On the inner peripheral surface of the land portion 11, a plurality of tooth forming grooves 11a and groove forming teeth 11b having a shape corresponding to the tooth portion and the groove portion of the gear portion 101 are formed.

The guide portion 12 is continuously formed at the first end portion E1 (upper end portion in FIG. 2) in the axial direction of the land portion 11. The guide portion 12 is a portion where the enlarged diameter portion 103 is iron-molded on the outer peripheral surface of the shaft-shaped material S100, and the introduction molding groove 12a and the groove forming tooth continuous with the tooth forming groove 11a are formed on the inner peripheral surface of the guide portion 12. Introductory molded teeth 12b continuous with 11b are formed. The introduction molding groove 12a and the introduction molding tooth 12b have a shape corresponding to the introduction gear portion 103a. Further, the guide portion 12 has an inner diameter of the guide portion 12 from the upper end surface of the mold 10 toward the first end portion E1 of the land portion 11 in order to facilitate the introduction of the inserted shaft-shaped material S100 into the land portion 11. Is formed so as to reduce the diameter.

The land relief portion 13 is continuously formed at the second end portion E2 (lower end portion in FIG. 2) in the axial direction of the land portion 11. On the inner peripheral surface of the land relief portion 13, a plurality of relief grooves 13a and relief teeth 13b having an inner diameter larger than the tooth forming groove 11a and the groove forming tooth 11b of the land portion 11 are provided. It is continuously formed on the groove forming teeth 11b.

Here, a method of manufacturing the pinion gear 100 using the mold 10 will be described. The pinion gear 100 inserts the shaft-shaped material S100 from the guide portion 12 side toward the land relief portion 13 side (from the upper side to the lower side in FIG. 2) while rotating the shaft-shaped material S100 around the central axis. As a result, the gear portion 101 and the enlarged diameter portion 103 are iron-formed on the outer peripheral surface of the shaft-shaped material S100. The shaft-shaped material S100 in which the gear portion 101 and the diameter-expanded portion 103 are iron-formed is pulled out from the land relief portion 13 side to the guide portion 12 side while rotating the shaft-shaped material S100 around the central axis in the direction opposite to that at the time of insertion. As a result, it is removed from the mold 10.

In the manufacturing process of the pinion gear 100, the gear portion 101 is iron-formed on the outer peripheral surface of the portion of the shaft-shaped material S100 that has passed through the land portion 11. The axial length of the land portion 11 formed on the mold 10 is shorter than the axial length of the gear portion 101 formed on the pinion gear 100. The mold 10 is designed to improve the dimensional accuracy of the land portion 11 by setting the length of the land portion 11 in the axial direction to be short. Then, when the pinion gear 100 is forged, the shaft-shaped material S100 is sent while being guided by the land relief portion 13 of the gear portion 101 formed on the outer peripheral surface. Suppress blurring.

Further, the land relief portion 13 suppresses the deformation of the gear portion 101 formed on the outer peripheral surface of the shaft-shaped material S100 due to springback at the portion that has passed through the land portion 11 of the shaft-shaped material S100. The portion of the shaft-shaped material S100 that has passed through the land portion 11 passes through the land portion 11 again when the shaft-shaped material S100 is removed from the mold 10. Therefore, even if the gear portion 101 is deformed at the portion that has passed through the land portion 11, the mold 10 remolds the deformed gear portion 101, so that the gear portion 101 can be formed into a desired shape.

Next, with reference to FIG. 3, the conventional electric discharge machining electrode 501 used for manufacturing the mold 10 by the die-sinking electric discharge machining will be described. As shown in FIG. 3, the conventional electric discharge machining electrode 501 includes a first electrode 502 and a second electrode 503.

The first electrode 502 is used when processing the tooth forming groove 11a and the groove forming tooth 11b of the land portion 11 and the relief groove 13a and the relief tooth 13b of the land relief portion 13. On the outer peripheral surface of the first electrode 502, a plurality of convex portions 502a corresponding to the tooth forming grooves 11a formed in the land portion 11 and a plurality of concave portions 502b corresponding to the groove forming teeth 11b are formed. The convex portion 502a has a smaller diameter than the tooth forming groove 11a, and the concave portion 502b has a smaller diameter than the groove forming tooth 11b. The second electrode 503 is a portion for processing the guide portion 12, and the outer peripheral surface of the second electrode 503 is formed in a shape corresponding to the guide portion 12.

Next, the manufacturing process of the mold 10 using the conventional electric discharge machining electrode 501 will be described with reference to FIGS. 4A to 4C. As shown in FIG. 4A, when manufacturing the mold 10, the electric discharge machining electrode 501 is mounted on an electric discharge machine (not shown). Then, the electric discharge machine inserts the first electrode 502 into the prepared hole formed in advance in the mold material S10 while rotating the first electrode 502 around the central axis.

As shown in FIG. 4B, when the first electrode 502 inserted in the prepared hole reaches the formation position of the land portion 11, the electric discharge machine stops the rotation of the first electrode 502 around the central axis, and the first electrode 502 is first. The electrode 502 is reciprocated in the radial direction. The moving distance of the first electrode 502 in the radial direction at this time is d1. As a result, the inner peripheral surface of the prepared hole is subjected to electric discharge machining at a portion where the first electrode 502 is brought close to the pilot hole, and a tooth forming groove 11a and a groove forming tooth 11b are formed. Then, the reciprocating movement of the first electrode 502 in the radial direction is performed on the entire inner peripheral surface of the prepared hole by changing the angle, so that the land portion 11 is formed.

After the land portion 11 is formed, the electric discharge machine rotates the first electrode 502 around the central axis and sends the first electrode 502 further downward with an axial movement amount corresponding to the rotation amount. Then, when the entire first electrode 502 has passed the formation position of the land portion 11 (second end portion E2 of the land portion 11), the electric discharge machine stops the rotation of the first electrode 502 around the central axis. Again, the first electrode 502 is reciprocated in the radial direction. The radial movement distance d2 of the first electrode 502 when forming the land relief portion 13 is larger than the radial movement distance d1 of the first electrode 502 when forming the land portion 11. As a result, the inner peripheral surface of the prepared hole is subjected to electric discharge machining at a portion where the first electrode 502 is brought close to the pilot hole, and the relief groove 13a and the relief groove 13a having an inner diameter larger than that of the tooth forming groove 11a and the groove forming tooth 11b are set. Teeth 13b are formed. Then, the reciprocating movement of the first electrode 502 in the radial direction is performed on the entire inner peripheral surface of the prepared hole by changing the angle, so that the land relief portion 13 is formed.

Next, the electric discharge machine takes out the first electrode 502 from the mold 10. Then, after replacing the first electrode 502 mounted on the electric discharge machine with the second electrode 503, the electric discharge machine inserts the second electrode 503 at the forming position of the guide portion 12, and the guide portion 12 is subjected to electric discharge machining. To form.

Japanese Unexamined Patent Publication No. 11-207529

In the conventional method for manufacturing the mold 10 described above, the land portion 11 and the land relief portion 13 are processed by using the first electrode 502. The radial movement distance d2 of the first electrode 502 when forming the land relief portion 13 is different from the radial movement distance d1 of the first electrode 502 when forming the land portion 11. Therefore, when the conventional mold 10 is manufactured by electric discharge machining, the electric discharge machining electrode 501 is formed by separately forming the first electrode 502 forming the land portion 11 and the second electrode 503 forming the guide portion 12. There is a need to.

Therefore, in the conventional method for manufacturing the mold 10, the phase around the rotation axis of the first electrode 502 when forming the land portion 11 and the land relief portion 13 and the phase of the second electrode 503 when forming the guide portion 12 The phase around the rotation axis is likely to be out of phase. That is, the phase around the central axis of the land portion 11 and the land relief portion 13 and the phase around the central axis of the guide portion 12 are likely to deviate, and the accuracy of the mold 10 is lowered.

An object of the present invention is to provide a method for manufacturing an electrode for electric discharge machining and a mold, which can improve the accuracy of a mold.

The electrode for electric discharge machining of the present invention is a metal used for manufacturing a pinion gear having a gear portion having a plurality of tooth portions and a plurality of grooves on the outer peripheral surface of the shaft-shaped material by passing the shaft-shaped material in the axial direction. It is an electrode for electric discharge machining used when forming a mold by electric discharge machining. The mold has a plurality of tooth forming grooves formed in a shape corresponding to the plurality of tooth portions and a plurality of groove forming teeth formed in a shape corresponding to the plurality of groove portions on the inner peripheral surface. A land portion for ironing and forming the gear portion on the outer peripheral surface of the shaft-shaped material and a portion continuously formed at the first end portion in the axial direction of the land portion, and the shaft-shaped portion is formed on the land portion. A guide portion whose inner diameter is reduced from the end face of the mold toward the first end portion of the land portion so as to introduce a material, and a second end portion of the land portion in the axial direction are continuously formed. A relief groove having an inner diameter larger than that of the tooth forming groove of the land portion and a land relief portion having a relief tooth having an inner diameter larger than that of the groove forming tooth of the land portion on the inner peripheral surface. , Equipped with.

The electric discharge machining electrode is a portion of the land portion for machining the tooth forming groove and the groove forming tooth, and the electric discharge machining electrode is moved relative to the mold in the radial direction to form the tooth. A spiral convex portion formed in a shape corresponding to the tooth forming groove and the groove forming tooth and having a diameter smaller than that of the tooth forming groove so that the groove and the groove forming tooth are machined. A constricted portion having a spiral concave portion formed with a diameter smaller than that of the groove-formed tooth and a portion for processing the guide portion, and by moving the electric discharge machining electrode relative to the mold in the radial direction. A base end portion formed in a shape corresponding to the guide portion and having a diameter smaller than that of the guide portion, and a portion for machining the land relief portion so that the guide portion is machined. A tip portion formed in a shape corresponding to the land relief portion is provided so that the land relief portion is processed by moving the electric discharge machining electrode relative to the mold in the radial direction.

According to the electrode for electric discharge machining of the present invention, the constricted portion, the guide portion, and the tip portion are integrally formed. As a result, in the mold manufactured by electric discharge machining using the electrode for electric discharge machining, the central axis of the land portion and the land relief portion and the central axis of the guide portion can be surely coaxial with each other. The accuracy can be improved.

Further, the present invention is a method for manufacturing a mold using the above-mentioned electrode for electric discharge machining. According to the method for manufacturing a mold of the present invention, the mold can be surely aligned with the phase around the central axis of the land portion and the land relief portion and the phase around the central axis of the guide portion. The accuracy can be improved.

It is a front view of the pinion gear forged by using the die manufactured by the electric discharge machining using the electrode for electric discharge machining in one Embodiment of this invention. It is a figure which shows the manufacturing process of the pinion gear which used the die manufactured by the electric discharge machining using the electrode for electric discharge machining, and shows the state before passing a shaft-like material through a die. It is a front view of the conventional electrode for electric discharge machining. It is a figure which shows the manufacturing process of the mold by electric discharge machining using the conventional electrode for electric discharge machining, and shows the state before passing the 1st electrode through a pilot hole of a mold material. It is a figure which shows the manufacturing process of the mold by electric discharge machining using the conventional electrode for electric discharge machining, and shows the process of forming the land part using the first electrode. It is a figure which shows the manufacturing process of the mold by electric discharge machining using the conventional electrode for electric discharge machining, and shows the process of forming the land relief part using a 1st electrode. It is a front view of the electrode for electric discharge machining in one Embodiment of this invention. FIG. 5 is an enlarged projection drawing in which the cross-sectional shape of the constricted portion in the XX cross section of FIG. 5A and the cross-sectional shape of the tip portion in the YY cross section of FIG. 5A are superimposed. It is a figure which shows the manufacturing process of the mold by electric discharge machining using the electrode for electric discharge machining, and shows the state before passing the electrode for electric discharge machining through a pilot hole of a mold material. It is a figure which shows the manufacturing process of the mold by electric discharge machining using the electrode for electric discharge machining, and shows the process of inserting the electrode for electric discharge machining into the pilot hole of the mold material. It is a figure which shows the manufacturing process of the mold by electric discharge machining using the electrode for electric discharge machining, and shows the process of forming the land part, the guide part and the land relief part using the electrode for electric discharge machining. It is an enlarged view of the upper part of the figure shown in FIG. 6C.

(1. Configuration of electrode 1 for electric discharge machining)
Hereinafter, an embodiment to which the method for manufacturing an electrode for electric discharge machining and a mold according to the present invention is applied will be described with reference to the drawings. First, the electric discharge machining electrode 1 according to the embodiment of the present invention will be described with reference to FIGS. 5A and 5B.

As shown in FIG. 5A, the electric discharge machining electrode 1 is used when the mold 10 shown in FIG. 2 is formed by electric discharge machining. The electric discharge machining electrode 1 includes a constricted portion 2, a base end portion 3, and a tip portion 4. The constricted portion 2 is a portion for processing the tooth forming groove 11a and the groove forming tooth 11b of the land portion 11, and the outer diameter of the constricted portion 2 is set to be smaller than the inner diameter of the land portion 11. Specifically, on the outer peripheral surface of the constricted portion 2, a spiral convex portion 2a formed in a shape corresponding to the tooth forming groove 11a and a spiral concave portion 2b formed in a shape corresponding to the groove forming tooth 11b. And are formed. The outer diameter of the convex portion 2a is formed to be smaller than the inner diameter of the tooth forming groove 11a, and the outer diameter of the concave portion 2b is formed to be smaller than the inner diameter of the groove forming tooth 11b.

The base end portion 3 is a portion for processing the guide portion 12, and is continuously formed at the end portion in the axial direction of the constricted portion 2 (the upper end portion of the constricted portion 2 in FIG. 5A). The base end portion 3 is formed in a shape corresponding to the guide portion 12, and is formed to have a diameter smaller than the inner diameter of the guide portion 12. Further, on the outer peripheral surface of the base end portion 3, an introduction convex portion 3a continuous with the convex portion 2a and an introduction concave portion 3b continuous with the concave portion 2b are formed at a connection portion with the constricted portion 2. The introduction convex portion 3a is formed in a shape corresponding to the introduction molding groove 12a of the guide portion 12, and the introduction concave portion 3b is formed in a shape corresponding to the introduction molding tooth 12b.

The tip portion 4 is a portion for processing the land relief portion 13. The tip portion 4 is an axial end portion of the constriction portion 2 and is continuously formed at an end portion opposite to the base end portion 3 (the lower end portion of the constriction portion 2 in FIG. 5A), and is a tip portion. The outer diameter of 4 is set to be smaller than the inner diameter of the land relief portion 13 and the inner diameter of the land portion 11. Specifically, on the outer peripheral surface of the tip portion 4, a relief convex portion 4a having a shape corresponding to the relief groove 13a and a relief concave portion 4b having a shape corresponding to the relief tooth 13b are formed. The outer diameter of the relief convex portion 4a is formed to be smaller than the inner diameter of the relief groove 13a and the inner diameter of the tooth forming groove 11a, and the outer diameter of the relief recess 4b is the inner diameter of the relief tooth 13b and the inner diameter of the groove forming tooth 11b. It is formed with a smaller diameter than.

Then, as shown in FIG. 5B, the outer diameter of the tip portion 4 is set to a dimension larger than the outer diameter of the constricted portion 2. Specifically, the outer diameter of the relief convex portion 4a (maximum outer diameter φ1 of the tip portion 4) is set to be larger than the outer diameter of the convex portion 2a (maximum outer diameter φ2 of the constricted portion 2), and the relief concave portion 4b The outer diameter of is set to a size larger than the outer diameter of the recess 2b. The dimensional difference between the outer diameter of the relief convex portion 4a and the outer diameter of the convex portion 2a is equivalent to the dimensional difference between the inner diameter of the relief groove 13a and the inner diameter of the tooth forming groove 11a. Similarly, the dimensional difference between the outer diameter of the relief recess 4b and the outer diameter of the recess 2b is equivalent to the dimensional difference between the inner diameter of the relief tooth 13b and the inner diameter of the grooved tooth 11b.

(2. Manufacturing method of mold 10)
Next, a method of manufacturing the mold 10 using the electrode 1 for electric discharge machining will be described with reference to FIGS. 6A to 6D. As shown in FIG. 6A, when manufacturing the mold 10, the electric discharge machining electrode 1 is mounted on an electric discharge machine (not shown). Then, the electric discharge machine rotates the electric discharge machining electrode 1 around the central axis with respect to the prepared hole formed in advance in the mold material S10, and moves from the tip portion 4 with an axial movement amount corresponding to the rotation amount. The electrode 1 for electric discharge machining is inserted (insertion step).

As shown in FIGS. 6B to 6D, when the electric discharge machining electrode 1 is inserted into the pilot hole up to the proximal end portion 3, the electric discharge machine stops the rotation around the central axis of the electric discharge machining electrode 1 and discharges. The machining electrode 1 is moved in the radial direction. As a result, the inner peripheral surface of the pilot hole is subjected to electric discharge machining at a portion where the electric discharge machining electrode 1 is brought close to the pilot hole, and the tooth forming groove 11a, the groove forming tooth 11b, the introduction molding groove 12a, the introduction molding tooth 12b, A relief groove 13a and a relief tooth 13b are formed. Then, the reciprocating movement of the electric discharge machining electrode 1 in the radial direction is performed on the entire inner peripheral surface of the prepared hole by changing the angle, so that the land portion 11, the guide portion 12, and the land relief portion 13 are formed at the same time. (Formation process).

As described above, the electrode 1 for electric discharge machining has a constricted portion 2, a base end portion 3, and a tip portion 4 integrally formed. The outer diameter of the tip portion 4 is set to a size larger than the outer diameter of the constricted portion 2, and the difference between the outer diameter of the tip portion 4 and the outer diameter of the constricted portion 2 is the inner diameter of the land relief portion 13. Is equivalent to the difference between the inner diameter of the land portion 11 and the inner diameter of the land portion 11. Therefore, in the die-sinking electric discharge machining using the electric discharge machining electrode 1, the die 10 can simultaneously form the land portion 11, the guide portion 12, and the land relief portion 13. Therefore, the electric discharge machining electrode 1 can efficiently manufacture the mold 10.

Further, since the tip portion 4 is formed to have a smaller diameter than the land portion 11, it can pass through the land portion 11. That is, after the land portion 11, the guide portion 12, and the land relief portion 13 are formed by electric discharge machining, the electric discharge machining electrode 1 has an axial movement amount corresponding to the rotation amount while rotating the electric discharge machining electrode 1. By retracting in the axial direction, the mold 10 can be pulled out from the guide portion 12 side. As a result, the electric discharge machining electrode 1 can integrally form the constricted portion 2, the base end portion 3, and the tip portion 4, and the land portion 11, the guide portion 12, and the land can be integrally formed by using the electric discharge machining electrode 1. The relief portion 13 can be formed at the same time.

(3. Others)
Although the present invention has been described above based on the above-described embodiment, the present invention is not limited to the above-described embodiment, and it is easy that various modifications and improvements can be made without departing from the spirit of the present invention. It can be inferred from.

(4. Effect)
As described above, the electric discharge machining electrode 1 in the present invention is a gear portion 101 having a plurality of teeth and a plurality of grooves on the outer peripheral surface of the shaft-shaped material S100 by passing the shaft-shaped material S100 in the axial direction. This is an electric discharge machining electrode 1 used when the mold 10 used for manufacturing the pinion gear 100 provided with the above is formed by electric discharge machining.

The mold 10 has a plurality of tooth forming grooves 11a formed in a shape corresponding to a plurality of tooth portions and a plurality of groove forming teeth 11b formed in a shape corresponding to the plurality of groove portions on the inner peripheral surface. , A portion formed continuously on the land portion 11 for ironing and forming the gear portion 101 on the outer peripheral surface of the shaft-shaped material S100 and the first end portion E1 in the axial direction of the land portion 11, and the shaft is formed on the land portion 11. The guide portion 12 whose inner diameter expands from the end surface of the mold 10 toward the first end portion E1 of the land portion 11 so as to introduce the shape material S100, and the second end portion E2 in the axial direction of the land portion 11 are continuous. The inner peripheral surface has a relief tooth 13b having an inner diameter larger than that of the groove forming tooth 11b of the land portion 11 and a relief groove 13a having an inner diameter larger than that of the tooth forming groove 11a of the land portion 11. A land relief unit 13 is provided.

The electric discharge machining electrode 1 is a portion for machining the tooth forming groove 11a and the groove forming tooth 11b of the land portion 11, and the electric discharge machining electrode 1 is moved relative to the mold 10 in the radial direction to form a tooth forming groove. A spiral convex portion 2a formed in a shape corresponding to the tooth forming groove 11a and the groove forming tooth 11b and having a diameter smaller than that of the tooth forming groove 11a so that the 11a and the groove forming tooth 11b are machined. A constricted portion 2 having a spiral concave portion 2b formed with a diameter smaller than that of the groove forming tooth 11b and a portion for machining the guide portion 12, and the electric discharge machining electrode 1 is moved relative to the mold 10 in the radial direction. The base end portion 3 formed in a shape corresponding to the guide portion 12 and having a diameter smaller than that of the guide portion 12 and the portion for machining the land relief portion 13 are formed so that the guide portion 12 is machined. The tip portion 4 is formed in a shape corresponding to the land relief portion 13 so that the land relief portion 13 is processed by moving the electric discharge machining electrode 1 relative to the mold 10 in the radial direction. , Equipped with.

According to the electric discharge machining electrode 1, the constricted portion 2, the proximal end portion 3, and the tip end portion 4 are integrally formed. As a result, the mold 10 manufactured by electric discharge machining using the electric discharge machining electrode 1 ensures that the phase around the central axis of the land portion 11 and the land relief portion 13 and the phase around the central axis of the guide portion 12 are aligned. Since they can be aligned, the accuracy of the mold 10 can be improved.

In the electric discharge machining electrode 1 described above, the tip portion 4 is formed to have a smaller diameter than the land portion 11. According to the electric discharge machining electrode 1, the tip portion 4 can pass through the land portion 11. That is, in the electric discharge machining electrode 1, after the land portion 11, the guide portion 12, and the land relief portion 13 are formed by electric discharge machining, the electric discharge machining electrode 1 can be extracted from the guide portion 12 side. As a result, the electric discharge machining electrode 1 can integrally form the constricted portion 2, the base end portion 3, and the tip portion 4, and the land portion 11, the guide portion 12, and the land can be integrally formed by using the electric discharge machining electrode 1. The relief portion 13 can be formed at the same time.

In the above-mentioned electrode 1 for electric discharge machining, the dimensional difference in the radial direction between the constricted portion 2 and the tip portion 4 is equivalent to the dimensional difference in the radial direction between the land portion 11 and the land relief portion 13. As a result, the electric discharge machining electrode 1 can simultaneously form the land portion 11, the guide portion 12, and the land relief portion 13.

Further, in the method for manufacturing the mold 10 of the present invention, the above-mentioned electrode 1 for electric discharge machining is used. According to the manufacturing method of the mold 10, the mold 10 can ensure that the phase around the central axis of the land portion 11 and the land relief portion 13 and the phase around the central axis of the guide portion 12 are aligned with each other. Therefore, the accuracy of the mold 10 can be improved.

In the method for manufacturing the die 10 described above, the electric discharge machining electrode 1 is tipped at the tip of the electric discharge machining electrode 1 while rotating the electric discharge machining electrode 1 about the pilot hole formed in the mold material S10 from which the die 10 is manufactured. By inserting the electric discharge machining electrode 1 from the portion 4 to the base end portion 3 and inserting the electric discharge machining electrode 1 into the pilot hole and then reciprocating the electric discharge machining electrode 1 in the radial direction, a land is placed on the inner peripheral surface of the pilot hole. A forming step of simultaneously forming a portion 11, a guide portion 12, and a land relief portion 13 is provided.

In this method of manufacturing the mold 10, since the land portion 11, the guide portion 12, and the land relief portion 13 can be formed at the same time by the forming step, the mold 10 can be efficiently manufactured.

1: Electrode for electric discharge machining, 2: Constricted part, 2a: Convex part, 2b: Concave part, 3: Base end part,
4: Tip part, 10: Mold, 11: Land part, 11a: Tooth forming groove, 11b: Grooving tooth, 12: Guide part, 13: Land relief part, 13a: Relief groove, 13b: Relief tooth, 100: Pinion gear, 101: Gear part, E1: First end part, E2: Second end part, S10: Mold material, S100: Shaft-shaped material

Claims (5)

By passing the shaft-shaped material in the axial direction, a mold used for manufacturing a pinion gear having a gear portion having a plurality of tooth portions and a plurality of grooves on the outer peripheral surface of the shaft-shaped material is formed by die-sinking electric discharge machining. It is an electrode for electric discharge machining used when
The mold is
The axial material having a plurality of tooth forming grooves formed in a shape corresponding to the plurality of tooth portions and a plurality of groove forming teeth formed in a shape corresponding to the plurality of groove portions on the inner peripheral surface. A land portion for ironing and forming the gear portion on the outer peripheral surface of the
A portion continuously formed at the first end portion in the axial direction of the land portion, and the first end portion of the land portion from the end face of the mold so as to introduce the axial material into the land portion. A guide part whose inner diameter decreases toward the part and
A relief groove that is continuously formed at the second end portion of the land portion in the axial direction and has an inner diameter larger than that of the tooth forming groove of the land portion, and the groove forming tooth of the land portion. A land relief part that has a relief tooth with a larger inner diameter than the inner peripheral surface,
With
The electrode for electric discharge machining is
The land portion is a portion for processing the tooth forming groove and the groove forming tooth, and the tooth forming groove and the groove forming tooth are formed by moving the electric discharge machining electrode relative to the mold in the radial direction. A spiral convex portion formed in a shape corresponding to the tooth forming groove and the tooth forming groove so as to be machined, and having a diameter smaller than that of the tooth forming groove, and a diameter smaller than that of the groove forming tooth. A constriction with a formed spiral recess and
It is a part for processing the guide portion, and is formed in a shape corresponding to the guide portion so that the guide portion is processed by moving the electric discharge machining electrode relative to the mold in the radial direction. At the same time, the base end portion formed to have a diameter smaller than that of the guide portion and
A portion for processing the land relief portion, and a shape corresponding to the land relief portion so that the land relief portion is processed by moving the electric discharge machining electrode relative to the mold in the radial direction. With the tip formed in
Electrode for electric discharge machining. The electrode for electric discharge machining according to claim 1, wherein the tip portion has a diameter smaller than that of the land portion. The electrode for electric discharge machining according to claim 1 or 2, wherein the dimensional difference in the radial direction between the constricted portion and the tip portion is equivalent to the dimensional difference in the radial direction between the land portion and the land relief portion. A method for manufacturing a mold using the electrode for electric discharge machining according to any one of claims 1-3. Insertion into which the electric discharge machining electrode is inserted from the tip end portion to the base end portion while rotating the electric discharge machining electrode about an axis in a prepared hole formed in the mold material from which the mold is manufactured. Process and
After inserting the electric discharge machining electrode into the pilot hole, the electric discharge machining electrode is reciprocated in the radial direction to provide the land portion, the guide portion, and the land relief portion on the inner peripheral surface of the pilot hole. The method for manufacturing a mold according to claim 4, further comprising a forming step of forming at the same time.

Images