JPH0712515B2 - Bevel gear plastic working method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a bevel gear plastic working method and apparatus for manufacturing a bevel gear by cold forging.

[Conventional technology]

Generally, bevel gears are widely used for power transmissions of various machines or differentials of self-propelled vehicles such as automobiles and tractors.

Conventionally, such a bevel gear has been disclosed in, for example, Japanese Patent Application Laid-Open No. 57-177845.
It is manufactured by the method as disclosed in the publication.

FIG. 6 shows a bevel gear plastic working apparatus disclosed in this publication. In the figure, reference numeral 11 denotes a die having a hole portion 15 into which a bevel gear forming material 13 is inserted. .

In front of the hole portion 15 of the die 11, a tooth profile portion 17 having a shape corresponding to the tooth profile of the bevel gear to be molded is carved.

An open portion 19 having a shape as shown in FIG. 7 is formed in front of the tooth profile 17 so as to communicate with the tooth profile 17.

In the drawing, reference numeral 21 indicates a punch, reference numeral 23 indicates a knockout pin, and reference numeral 25 indicates a shaft hole of the material 13.
27 shows a pin inserted into 27.

In the plastic working device for bevel gears as described above, after the raw material 13 is accommodated in the hole portion 15, the raw material 13 is sequentially extruded by the punch 21 so as to be filled in the tooth profile portion 17, and further, the eighth
As shown in the drawing, a bevel gear is forged by extruding a part of the material 13 as an extra thickness in an open portion 19 formed in front of the toothed portion 17 of the die 11.

Then, according to such a plastic working method of the bevel gear, since the open portion 19 is provided in front of the toothed portion 17, extra raw material will escape to the open portion 19, regardless of the volume of the raw material. Since it is possible to perform forging by steady plastic flow under a constant pressure, it is possible to effectively prevent deterioration of accuracy due to variation in material volume, and excess lubricating oil, lubricant, scale, etc. are discharged from the open portion 9. Therefore, there is an effect that it is possible to effectively prevent a decrease in product accuracy due to the above.

[Problems to be Solved by the Invention]

However, in such a conventional plastic working method for a bevel gear, as shown in FIG. 7, since the shape of the open portion 19 from which the excess thickness is extruded is a tooth profile that is continuous with the tooth profile portion 17, this open When removing the excess thickness extruded to the part 19 by cutting, etc., there is a problem that it becomes intermittent cutting and burrs are generated, and this burr interferes with the mating gear, so it is necessary to surely remove the burr. .

On the other hand, in order to solve such a problem, the opening portion 19 is formed in a circular shape instead of a tooth shape, and the diameter of the opening portion is
Same or smaller than the root diameter of the conical tip of the bevel gear,
It is possible to make it slightly larger, but in these cases, as shown in FIG. 9, the root portion of the conical tip portion of the bevel gear 31 is attached to the root portion of the die during the forward extrusion. The material that has been pushed away by the tool rises like a burr and the burr-like part
There was a problem that 33 was formed.

Then, as shown in FIG. 10, the diameter of the opening portion 35 is equal to that of the bevel gear.
When the root diameter of the conical tip portion 31 is smaller than that of the conical tip portion, there is a problem that the burr-shaped portion 33 hits the conical tip portion of the die 37 to cause an overlapping defect 39.

Further, when the diameter of the open portion is larger than the root diameter of the conical tip portion of the bevel gear 31, the burr-shaped portion 33 hits the root portion of the conical tip portion of the bevel gear 31, as shown in FIG. In addition, there was a problem that an overlapping defect 41 was generated at the tooth base.

Further, when the burr-like portion 33 is generated, this burr-like portion 33 is
Since it comes into contact with the tooth 37 first, there is a problem in that the material is not buried in the tooth tip bottom portion and the extra thickness portion 43 is generated.

The present invention solves the above problems, and provides a bevel gear plastic working method and apparatus capable of reliably eliminating the occurrence of a burr-like portion at the root portion of the conical tip portion of the bevel gear. The purpose is to do.

[Means for Solving the Problems]

A plastic working method for a bevel gear according to claim 1 is a die in which a tooth forming profile of a bevel gear is continuously formed in front of a material feeding part and a die side opening hole is continuously formed in front of the tooth forming profile. When,
After inserting the material for forming the bevel gear into the material inserting portion of the die having the counter punch which is inserted into the die-side opening hole of this die and whose tip is located in the tooth forming shape portion, the material is Pressed with a punch in the center of which a punch side open hole with a diameter larger than the tip diameter of the counter punch is formed,
The material is extruded forward to the tooth forming portion of the die to form the tooth profile of the bevel gear, and the material is extruded rearward to the punch side open hole of the punch to form the boss portion of the bevel gear.

A plastic working method for a bevel gear according to claim 2 is a die in which a tooth forming portion of a bevel gear is continuously engraved in front of a material feeding portion and a die side opening hole is continuously formed in front of the tooth forming portion. When,
A bevel gear forming material having a through hole formed in the center is placed in the material feeding portion of the die having a counter punch that is inserted into the die side opening hole of this die and has a tip located in the tooth forming shape portion. After inserting into the through hole so that a mandrel portion formed at the tip of the counter punch and smaller in diameter than the tip diameter of the counter punch is inserted, a punch having a diameter larger than the tip diameter of the counter punch is centered around this material. The material is pressed forward by the punch with the side open hole to push the material forward to the tooth forming shape of the die to form the tooth profile of the bevel gear, and the material is moved backward between the punch side opening hole of the punch and the mandrel. It is to be extruded to form a boss portion with a hole of a bevel gear.

The plastic working method of the bevel gear according to claim 3 is the method according to claim 1 or 2.
In the above, the counter punch is moved downward before the completion of molding.

The plastic working device for a bevel gear according to claim 4 is a die in which a tooth forming portion of a bevel gear is continuously engraved in front of a material feeding portion and a die side opening hole is continuously formed in front of the tooth forming portion. When,
A counter punch that is inserted into the die side opening hole of this die and has its tip positioned in the tooth forming shape part, and a punch side opening hole that is inserted into the material introduction part of the die and has a punch side hole with a diameter larger than the tip diameter of the counter punch. And a punch to be formed.

According to a fifth aspect of the present invention, in the plastic working device for a bevel gear according to the fourth aspect, a mandrel portion having a diameter smaller than the tip diameter of the counter punch is formed at the tip of the counter punch.

According to a sixth aspect of the present invention, there is provided a plastic working device for bevel gears according to the fourth and fifth aspects.
In the above, the counter punch can be moved downward before the completion of molding.

[Work]

In the plastic working method for a bevel gear according to claim 1 and the plastic working device for a bevel gear according to claim 4, when a material for forming a bevel gear is inserted into a material feeding portion and the material is pressed by a punch,
The material is bent by the punch side opening hole of the punch and the action of the counter punch, and due to this curvature and the action of pulling the front surface of the material to the center by the counter punch, the outer side of the counter punch on the front surface of the material is directed toward the outer circumference. A sloping surface that becomes higher is generated.

In the bevel gear plastic working method of the second aspect and the bevel gear plastic working apparatus of the fifth aspect, the mandrel portion is inserted into the through hole of the material, and thereby the boss portion having the hole is formed.

In the plastic working method for a bevel gear according to claim 3 and the plastic working device for a bevel gear according to claim 6, the counter punch is moved downward before the completion of forming, and a relatively long boss portion is provided on the cone tip end side of the bevel gear. It is formed.

〔Example〕

 Hereinafter, the details of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of a plastic working apparatus for bevel gears according to the present invention, in which reference numeral 51 denotes a die.

The die 51 is formed with a circular material feeding portion 53, and a tooth forming portion 55 of the bevel gear is formed continuously in front of the material feeding portion 53.

A circular die-side opening hole 57 is formed continuously in front of the tooth forming portion 55.

A counter punch 61 is inserted into the die-side opening hole 57 via an eject ring 59, and the tip end of the counter punch 61 is located inside the tooth forming profile 55.

In the drawing, reference numeral 63 indicates a punch fitted into the material feeding portion 53 of the die 51, and the punch side opening hole having a diameter D larger than the tip diameter d of the counter punch 61 is provided at the center of the punch 63. 65 are formed.

Manufacture of a bevel gear using the plastic working device for a bevel gear configured as described above is performed as described below.

That is, first, as shown in FIG. 1, a cylindrical material 67 for forming a bevel gear is inserted into the material inserting portion 53 of the die 51.

After this, this material 67 is pressed by the punch 63 and the second
As shown in the figure, the material 67 is extruded forwardly onto the tooth forming profile 55 of the die 51 to form the tooth profile of the bevel gear.

Then, together with the forward extrusion, the material 67 is extruded backward into the punch side opening hole 65 of the punch 63, and finally the third
As shown, the boss portion 69 of the bevel gear is formed.

Thus, in the above-described bevel gear plastic working method and apparatus thereof, the material 67 for forming the bevel gear is inserted into the material feeding section 53, and when this material 67 is pressed by the punch 63, the As shown in FIG. 2, the material 67 is curved by the action of the punch side opening hole 65 of the punch 63 and the counter punch 61, and this curvature and the front surface of the material 67 are the counter punch 61.
By the action of being pulled toward the center by the action, an inclined surface 71 that rises toward the outer periphery is generated outside the counter punch 61 on the front surface of the material 67, and as shown in FIG. It is possible to surely eliminate the occurrence of a burr-like portion on the tooth root portion 77 of the conical tip portion 75.

That is, as shown in FIG. 2, the inclined surface 71 generated as described above is always caused by the counter punch 61.
Because it is drawn like the arrow A toward the center of the material 67,
A burr-like portion is less likely to be generated at the tooth base portion 79 which is the conical tip end portion 75 of the bevel gear 73, and even if a burr-like portion is to be generated, the inclined surface 71 makes the corner portion obtuse.

Further, the conical tip portion 75 of the bevel gear 73 is generated due to the generation of the inclined surface 71.
As shown in FIG. 2, the tooth tip 81 of the die 51
Since it abuts against the conical tip portion 83 of the die, at the end of the plastic working, as shown in FIG. Will no longer occur.

Further, in the vicinity of the bottom dead center of the punch 63, the opening area on the rear side of the material 67 becomes larger than the opening area on the front side, so that as shown by the arrow B in FIG.
67 flows, so that the formation of burrs at the root 77 of the conical tip portion 75 of the bevel gear 73 is further suppressed.

Further, according to the above-described bevel gear plastic working method and apparatus, as shown in FIG. 3, the material 67 is extruded rearward into the punch-side opening hole 65 of the punch 63, so that a cylindrical material can be easily formed. It becomes possible to form the boss portion 69 on the.

FIG. 4 shows another embodiment of the bevel gear plastic working apparatus of the present invention. In this embodiment, a mandrel portion 85 having a diameter smaller than the tip diameter of the counter punch 61 is provided at the tip of the counter punch 61. Has been formed.

In such a device, a material 87 having a through hole 89 formed at the center is used as a material, and the mandrel portion 85 is inserted into the through hole 89 of the material 87 and the operation shown in FIG. The plastic working is performed in the same manner as in the example.

With this bevel gear plastic working method and apparatus, almost the same effects as those of the embodiment shown in FIG. 1 can be obtained, but in this embodiment, a bevel gear having a hole in the boss portion 91 can be easily formed. It becomes possible to obtain it.

FIG. 5 shows still another embodiment of the plastic working device for a bevel gear according to the present invention. In this embodiment, the counter punch 61 is formed before the completion of forming, that is, near the bottom dead center of the punch 63. It can be moved downward, and is moved downward before the completion of molding.

The counter punch 61 can be lowered by receiving the counter punch 61 with a cushion at normal pressure and killing it at the bottom dead center, or by exhausting this cushion near the bottom dead center. Methods etc. are considered.

With this bevel gear plastic working method and apparatus, almost the same effects as in the embodiment shown in FIG. 1 can be obtained, but in this embodiment, the conical tip end side of the bevel gear is relatively long and long. It becomes possible to easily form the L boss portion 93.

〔The invention's effect〕

As described above, in the plastic working method for a bevel gear according to claim 1 and the plastic working device for a bevel gear according to claim 4, a material for forming a bevel gear is inserted into the material feeding portion, and the material is punched. When pressure is applied, the material is bent by the action of the punch side opening hole of the punch and the counter punch during the forming, as shown in FIG. 2, and this curvature and the front surface of the material are pulled to the center by the counter punch. Due to the action, an inclined surface that rises toward the outer periphery is generated outside the counter punch on the front surface of the material, and it is possible to reliably eliminate the occurrence of a burr-like portion at the root of the conical tip of the bevel gear. be able to.

According to the bevel gear plastic working method of the second aspect and the bevel gear plastic working apparatus of the fifth aspect, the boss portion having the hole can be easily obtained.

The bevel gear plastic working method according to the third aspect and the bevel gear plastic working apparatus according to the sixth aspect have an advantage that a relatively long boss portion can be easily obtained on the conical tip end side of the bevel gear.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a plastic working device for a bevel gear according to the present invention. FIG. 2 is a longitudinal sectional view showing a state where the punch shown in FIG. 1 is lowered halfway. FIG. 3 is a longitudinal sectional view showing a state where the punch of FIG. 1 is lowered to the bottom dead center. FIG. 4 and FIG. 5 are vertical sectional views showing another embodiment of the plastic working device for a bevel gear according to the present invention. FIG. 6 is a vertical sectional view showing a conventional plastic working device for a bevel gear. FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. FIG. 8 is a longitudinal sectional view showing a state at the end of forming by the plastic working device for a bevel gear shown in FIG. 9 to 11 are explanatory views showing defects such as burr-like portions which occur in the bevel gear. [Explanation of symbols for main parts] 51 …… Die 53 …… Material injection section 55 …… Tooth forming section 57 …… Die side opening hole 61 …… Counter punch 63 …… Punch 65 …… Punch side opening hole 67… Material 69,91,93 Boss 85 Mandrel 89 Through hole.

Claims (6)

[Claims] 1. A die in which a tooth forming profile of a bevel gear is continuously formed in front of a material feeding section and a die side open hole is continuously formed in front of this tooth forming profile, and a die side of this die. After inserting a bevel gear forming material into the material feeding part of the die having a counter punch which is inserted into the open hole and whose tip is located in the tooth forming shape part, the counter punch is centered around this material. The punch side open hole with a diameter larger than the tip diameter of the punch is pressed to push the material forward into the tooth forming part of the die to form the tooth profile of the bevel gear, and the material is punch side opening hole of the punch. A plastic working method for a bevel gear, which comprises extruding the bevel gear backwards to form a boss portion of the bevel gear. 2. A die in which a tooth forming portion of a bevel gear is continuously formed in front of a material feeding portion and a die side opening hole is continuously formed in front of the tooth forming portion, and a die side of this die. A bevel gear forming material having a through hole formed in the center of the material inserting portion of the die having a counter punch whose tip is positioned in the tooth forming shape portion and which is inserted into the open hole is formed in the through hole. After inserting so that a mandrel part formed at the tip of the counter punch and smaller than the tip diameter of the counter punch is inserted, a punch side open hole with a diameter larger than the tip diameter of the counter punch is formed at the center of this material. Is pressed by the punch to push the material forward to the tooth forming shape of the die to form the tooth profile of the bevel gear, and the material is pushed backward between the punch side opening hole of the punch and the mandrel portion. With hole Plastic working method of bevel gears and forming a boss. 3. The method of plastic working a bevel gear according to claim 1, wherein the counter punch is moved downward before the completion of forming. 4. A die in which a tooth forming portion of a bevel gear is continuously formed in front of a material feeding portion and a die side opening hole is continuously formed in front of the tooth forming portion, and a die side of this die. A counter punch having a tip inserted into the open hole and having its tip positioned in the tooth forming profile; and a punch having a punch side open hole having a diameter larger than the tip diameter of the counter punch formed at the center and inserted into the material feeding section of the die. A plastic working device for a bevel gear, comprising: 5. The bevel gear plastic working apparatus according to claim 1, wherein a mandrel portion having a diameter smaller than the tip diameter of the counter punch is formed at the tip of the counter punch. 6. The plastic working device for bevel gears according to claim 4, wherein the counter punch is movable downward before the completion of forming.