JPH0263629A - Helical gear forming die - Google Patents

Abstract

PURPOSE:To reduce the bending stress of a die tooth form part by constituting the die tooth form part of an intermediate tooth form part and a final tooth form part, and also, setting a lead of the final tooth form part to the same as a product lead and controlling an intermediate lead by a specific condition related to a lateral cross- sectional area of a gear and a final lead. CONSTITUTION:A die hole 33 of a helical gear forming die 32 is formed by dividing it into an intermediate tooth form part 37 and a final tooth form part 39. The intermediate tooth form part 37 operates so as to give rotational force to a stock, and a final lead L0 being a lead of the final tooth form part 39 is set to the same as a product lead. On the other hand, an intermediate lead L1 in the intermediate tooth form part 37 is controlled to a value obtained by multiplying a lateral cross-sectional area A0 of a gear by the final lead L0 and dividing this multiplied value by a lateral cross-sectional area of a partially fabricated item in the intermediate tooth form part 37. In such a way, a rotation angle of a stock of the intermediate tooth form part 37 and the final tooth form part 39 at the time when a punch is inserted is held in the same. Accordingly, since an unformed part of the intermediate tooth form part 37 does not obstruct a rotation of the stock, bending stress of the whole tooth form part 35 is reduced remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a helical gear forming die used for forward extrusion forming of a helical gear.

[Conventional technology]

Generally, when forming a helical gear as shown in FIG. 7 by cold forging, forward extrusion is used.

FIG. 8 shows a mold for manufacturing a helical gear by forward extrusion molding, with the left side of the figure showing the state before molding, and the right side of the figure showing the state after molding.

In the figure, reference numeral 11 indicates a die for forming a helical gear in which a toothed portion 15 is formed in a die hole 13.

A punch 17 is inserted into the gouging hole 13 of this die 11 from above, and a mandrel 19 is inserted through the punch 17.

On the other hand, the die 11 is supported by an insert plate 23 via a die anvil 21.
A knockout block 25 whose upper end is inserted into the die 11 is inserted through the die 1 .

A knockout pin 2 is inserted into the insert plate 23 on the lower surface of this knockout block 25.
7 is in contact with the upper surface.

In such a mold, the punch 17 and the mandrel 19
By moving the material 29 downward, the material 29 in the die hole 13 is removed.
is forward extruded to produce a helical gear.

[Problem to be solved by the invention]

However, in such a conventional mold, there is a problem that a large bending stress acts on the toothed part 15 of the die 11, which may cause the toothed part 15 to be damaged, and the life of the toothed part 15 is shortened. .

That is, in such a mold, the cylindrical material 29 is
As it is extruded by the punch 17, a tooth profile is formed, and a rotational force is applied to the tooth profile part by the tooth profile part 15 of the die 11, and this rotational force attempts to rotate the entire material 29, but the material 29 A large amount of pressure is generated between the unformed portion and the die hole 13, and this pressure prevents the rotation of the material 29 and causes abnormal bending stress to act on the toothed portion 15.

The present invention solves the above-mentioned problems, and aims to provide a die for forming helical gears that can significantly reduce the bending stress acting on the tooth profile compared to the prior art.

[Means to solve the problem]

The helical gear forming die according to the present invention is a helical gear forming die in which a tooth profile portion for forming a helical gear by forward extrusion molding of a material is formed in a die hole into which a punch is inserted. In the above, the tooth profile section is composed of an intermediate tooth profile section located on the punch insertion side and a final tooth profile section following this, and the final lead that is the lead of the final tooth profile section is the product lead of the helical gear. be the same, and on the other hand,
The intermediate lead, which is the lead of the intermediate tooth profile, is the value obtained by multiplying the cross-sectional area of the helical gear by the final lead, and dividing this multiplied value by the cross-sectional area of the semi-finished product in the intermediate tooth profile. It is something.

[Function] In the helical gear forming die of the present invention, the tooth profile is composed of the intermediate tooth profile located on the punch insertion side and the final tooth profile following this, so the material is Rotational force is applied at the final tooth profile.

Then, the final lead, which is the lead of the final tooth profile, is the same as the product lead of the helical gear, and on the other hand, the intermediate lead, which is the lead of the intermediate tooth profile, is multiplied by the final lead by the cross-sectional area of the helical gear. Since this multiplied value was divided by the cross-sectional area of the semi-finished product at the intermediate tooth profile, the rotation angle of the material at the intermediate tooth profile due to insertion of the punch is the same as the rotation angle of the material at the final tooth profile. Become.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, details of the present invention will be described with reference to an embodiment shown in the drawings.

FIG. 1 shows an embodiment of the helical gear forming die of the present invention. In the figure, the reference numeral 31 indicates a die hole 33 in the center.
The die body that is formed is shown.

In this embodiment, the tooth profile 35 formed on the inner periphery of the die hole 33 is composed of an intermediate tooth profile 37 located on the punch insertion side and a final tooth profile 39 following this.

The tooth profile 41 formed in the intermediate tooth profile part 37 is for applying rotational force to the material, and as shown in FIG. 2, the tooth profile 41 is formed with a shorter tooth height than that of a helical gear. Also, the tooth profile is triangular rather than involute.

On the other hand, the tooth profile 43 formed in the final tooth profile portion 39 is for forming a predetermined helical gear on the material, and as shown in FIG. 3, the tooth profile is an involute tooth profile.

In this embodiment, the final lead LO, which is the lead of the final tooth profile 39, is the same as the product lead of the helical gear, while the intermediate lead LO, which is the lead of the intermediate tooth profile 37, is the fourth lead. The cross-sectional area AO of the helical gear shown in the figure is multiplied by the final gear LO, and this multiplied value is divided by the cross-sectional area A1 of the semi-finished product at the intermediate tooth profile portion 37 shown in FIG. There is.

That is, (AI)x (Ll) - (AO)x (LO).

Note that the lead here refers to a helical gear, intermediate tooth profile portion 37.
．． It refers to the amount by which the helical winding forming the tooth gap such as the final tooth profile portion 39 advances in one rotation.

Part 6 shows a mold for forward extrusion molding using such a helical gear molding die. The left side of the figure shows the state before molding, and the right side of the figure shows the state after molding. ing.

In the figure, reference numeral 45 indicates the helical gear forming die shown in FIG.

A punch 47 is inserted into the die hole 33 of the die 45 from above, and a mandrel 49 is inserted through the punch 47.

On the other hand, the die 45 is supported by the insert plate 53 via the die anvil 51.
1, a knockout block 55 whose upper end is inserted into the die 45 is inserted.

A knockout pin 5 inserted into the insert plate 53 is provided on the lower surface of the knockout block 55.
7 is in contact with the upper surface.

In such a mold, the punch 47 and the mandrel 49
By moving the material 29 downward, the material 29 in the hole 33 is
is forward extruded to produce a helical gear.

Therefore, in this mold, for example, the cross-sectional area AI of the semi-finished product in FIG. 5 is 200 mm2, the cross-sectional area AO of the helical gear in FIG. Assuming that the final lead LO of the tooth profile is 40 mm, the material 29 of the intermediate tooth profile 37 is rotated by 36 degrees by moving the punch 47 downward two steps, while the material 29 of the final tooth profile 39 is pushed forward by 40 degrees.
Similar to the material 29 of the intermediate tooth profile portion 37, it is rotated by 36 degrees.

That is, in the helical gear forming die configured as above, the tooth profile part 35 is composed of the intermediate tooth profile part 37 located on the bunch insertion side and the final tooth profile part 39 following this, so that the material 29 are the intermediate tooth profile portion 37 and the final tooth profile portion 3
At step 9, rotational force is applied.

Then, the final lead LO which is the lead of the final tooth profile portion 39
is the same as the product lead of the helical gear, and on the other hand, the intermediate lead L1, which is the lead degree of the intermediate tooth profile portion 37, is multiplied by the final lead O of the cross-sectional area AO of the helical gear, and this multiplied value is is the cross-sectional area A1 of the semi-finished product at the intermediate tooth profile portion 37
Since the value is divided by , the rotation angle of the material 29 at the intermediate tooth profile portion 37 due to insertion of the punch 47 and the rotation angle of the material at the final tooth profile portion 39 are the same.

That is, in the helical gear forming die configured as described above, since the unformed portion of the intermediate tooth section 37 rotates, the rotation of the material 29 is not hindered, and the bending stress acting on the tooth section 35 is reduced. can be significantly reduced compared to conventional methods.

In addition, in the embodiment described above, an example was described in which a triangular tooth profile 41 was formed in the intermediate tooth profile portion 37, but the present invention is not limited to such an embodiment, and it is also possible to form a tooth profile such as an arc shape. Of course, it is good to do so.

〔Effect of the invention〕

As described above, in the helical gear forming die of the present invention,
The tooth profile part is composed of an intermediate tooth profile part located on the punch insertion side and a final tooth profile part following this, and the final lead that is the lead of the final tooth profile part is the same as the product lead of the helical gear, On the other hand, the intermediate lead, which is the lead of the intermediate tooth profile, is obtained by multiplying the cross-sectional area of the helical gear by the final ratio, and dividing this multiplied value by the cross-sectional area of the semi-finished product in the intermediate tooth profile. This value has the advantage that the bending stress acting on the tooth profile can be significantly reduced compared to the conventional case.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of a die for forming a helical gear according to the present invention. FIG. 2 is a cross-sectional view of the helical gear forming die shown in FIG. 1 taken along the line . FIG. 3 is a cross-sectional view of the helical gear forming die shown in FIG. 1 taken along the line . FIG. 4 is a cross-sectional view of the product formed with the final tooth profile. FIG. 5 is a cross-sectional view of a semi-finished product formed with an intermediate tooth profile. FIG. 6 is a longitudinal sectional view showing a mold using the helical gear forming die of FIG. 1. FIG. 7 is a perspective view showing an example of a helical gear. FIG. 8 is a longitudinal sectional view showing an example of a conventional die for forming helical gears. [Explanation of symbols of main parts] 31...Die body 33...Die hole 35...Tooth profile booklet 37...Intermediate tooth profile section 39...Final tooth profile section 47...Punch. Figure Figure

Claims (1)

[Claims] (1) In a helical gear forming die in which a tooth profile part for forming a helical gear by forward extrusion molding of a material is formed in a die hole into which a punch is inserted, the tooth profile part is placed on the punch insertion side. It consists of an intermediate tooth profile section located at , and a final tooth profile section following this, and the final lead, which is the lead of the final tooth profile section, is the same as the product lead of the helical gear. The intermediate lead, which is a lead, is a value obtained by multiplying the cross-sectional area of the helical gear by the final lead, and dividing this multiplied value by the cross-sectional area of the semi-finished product at the intermediate tooth profile portion. Die for forming helical gears.