JPS62107839A - Method and aparatus for cold forging of toothed product - Google Patents

Abstract

PURPOSE:To obtain a toothed product improved in the tooth profile and accuracy of a material, after forming the tooth profile on the inner surface of the cylindrical material, by reduced forming the outer surface and in its restricted state, by coining its tooth profile with a tooth profile of a mandrel. CONSTITUTION:The cylindrical material A possessed of a slightly smaller inside diameter than the minor diameter of the tooth profile is inserted into the die 1. In the die 1, the mandrel 2 equipped the tooth profile 2a on its top end is passed through the material A and by compressive loading on the material A with the punch B, the spline shaped tooth profile is formed on the inner surface of the material A by the tooth profile 2a. The formation of tooth profile by the mandrel 2 is finished, the inner surface of the material A is reduced immediately at the inner surface 1b at the lower part of the die 1 to form the whole tooth profile of the material A smaller than the tooth profile 2a. After said forming is finished, the material A is knocked up by a knockout sleeve 4, the coining on the tooth profile of the material A is performed by the tooth profile 2a of the mandrel 2 to obtain the toothed product excellent in the shape and accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for cold forging a product having a tooth profile and an improvement in the apparatus thereof.

(Prior Art) Among products with tooth profiles, those with spline tooth profiles have conventionally been forged by cold extrusion. Figure 2 shows the main structure of a conventional cold forging device.

A cylindrical material A having an inner diameter slightly smaller than the small diameter of the tooth shape is inserted into the die 1. In the die 1, a mandrel 2 having a spline-shaped tooth profile 2a at its upper end penetrates the material A, and extrusion of the tooth profile begins by applying a compressive load to the material A with a punch 3.

(Problems to be Solved by the Invention) However, the conventional method described above has a problem in that the tooth profile of the material A is not formed in accordance with the tooth profile of the mandrel 2, and therefore is not suitable for products that require tooth profile precision. That is, FIG. 5 shows the cross-sectional shape of the inner tooth profile of the rough material formed by the above-mentioned conventional method, and the broken line indicates the tooth profile of the mandrel. The tooth profile is difficult to satisfy because the part is lacking in thickness.

The present invention aims to provide a cold forging method and an apparatus therefor which eliminates such problems.

(Means for Solving the Problems) As a means to solve the above problems, the present invention applies a cold forging method for products having tooth profiles to the inner surface of a cylindrical material.
A cisspline-shaped tooth profile is formed by the tooth profile of the mandrel, and the outer surface is subsequently drawn and formed, and then, with the outer surface restrained, the entire inner tooth profile is coined by the tooth profile of the mandrel. A device used in the forging method is configured to form an inner surface of a die slidably fitted into a die holder into an upper inner surface and a lower inner surface having a smaller diameter, and to make the upper inner surface correspond to the tooth profile of a mandrel. It is characterized by having a configuration provided in the.

(Function) In this configuration, first, a spline-shaped tooth profile is formed by the tooth profile of a mandrel on the inner surface of a cylindrical material. However, in forming at this stage, a shape in which part of the corner of the small diameter tooth tip is missing is formed. Therefore, it is not formed according to the tooth profile of the mandrel. Therefore, by subsequently drawing the outer surface of the material, the entire tooth profile on the inner surface of the material is made smaller than the tooth profile of the mandrel. By simultaneously pushing up the material during knockout and coining the tooth profile of the material with the tooth profile of the mandrel, the tooth profile shape and accuracy of the material can be improved.

In this method, the die is slidably inserted into the die holder, and the inner surface of the die is formed into an upper inner surface that corresponds to the tooth profile of the mandrel and a lower inner surface that has a smaller diameter. This makes it possible. In other words, the material that has been formed into a tooth shape by the teeth of the mandrel on the upper inner surface of the die is squeezed on the lower inner surface, and then during knockout, the die slides upward along with the material, so the outer surface of the material is restrained. The tooth profile of the material is coined with the tooth profile of the mandrel.

(Embodiment) Next, an embodiment of the present invention will be described with reference to FIG. In FIG. 1, the left side of the center line shows the entire state after completion of tooth formation on the inner surface of the material, and the right side of the center line shows the state after completion of coining of the tooth shape on the inner surface of the material.

First, to explain the cold forging apparatus according to the present invention, a die 1 is slidably inserted into a die holder 5. A punch 6 moves up and down inside the die 1, and the punch 3 is in a state in which the mandrel 2, which is inserted through the material A, is inserted into the punch 3. A spline-shaped tooth profile 2a is provided at the upper end of the mandrel 2. The inner surface of the die 1 consists of an upper inner surface 1a and a lower inner surface 1b having a smaller diameter than the upper inner surface 1a, and the upper inner surface 1a is provided so as to correspond to the tooth profile 2a of the mandrel 2. Note 4
is a knockout sleeve.

Next, the apparatus configured as described above was used.

The cold forging method according to the present invention will be explained.

First, a cylindrical material A whose inner diameter is slightly smaller than the small diameter of the tooth shape.
is inserted into the die 1 which is lowering due to its own weight.A mandrel 2 with a tooth profile 2a on the upper end is inserted into the die 1, and a compressive load is applied to the material A with the punch 3. As a result, a spline-shaped tooth profile is formed on the inner surface of the material A by the tooth profile 2a of the mandrel 2. Immediately after the tooth forming with the mandrel 2 is completed, the die 1 is
Start squeezing the outer surface of material A with the lower inner surface 1b of . Due to this drawing forming, the material moves in the inner diameter direction, so that the entire tooth profile of the material A becomes smaller than the tooth profile of the mandrel 2. This tooth forming and drawing are performed simultaneously until the ram bottom dead center.

After the above molding is completed, the material A is pushed up by the knockout sleeve 4. As mentioned above, since the entire tooth profile of the material A is smaller than the tooth profile of the mandrel 2, coining of the tooth profile of the material A with the tooth profile of the mandrel 2 is performed by this pushing up. In this case, the die 1 slides upward together with the material A due to the wall friction with the material A, and when coining the tooth profile, the material A is
restrains the outer surface of If you get knocked out even more,
The die 1 hits the locking part of the die holder 5, and only the material A is pushed up, completing the knockout. Therefore, by this method, it is possible to obtain a rough material with a good tooth shape and precision by cold forging.

The forging method and apparatus Vi according to the present invention are generally configured as described above. Note that the width of the tooth profile of the mandrel, the diameter of the mandrel, the cross-sectional reduction rate of the outer surface of the material during drawing forming, etc. can be selected as appropriate. (Effects of the Invention) As is clear from the above explanation, the present invention has This has the following effects.

In the invention of the cold forging method, after forming teeth on the inner surface of a cylindrical material, the outer surface is drawn and coined with the tooth profile of a mandrel while the outer surface is constrained. It is possible to improve the shape and accuracy. In addition, material costs are reduced compared to the conventional cutting process using broaching.

It is possible to reduce processing costs and is advantageous in terms of cost.

In the invention of a cold forging device, a die is slidably inserted into a die holder, and its inner surface is formed into an upper inner surface and a lower inner surface with a smaller diameter, and the upper inner surface corresponds to the tooth profile of the mandrel. This makes it possible to implement the above method efficiently with a clever configuration.

In other words, by applying a compressive load to the material with a punch, the inner surface of the material is inevitably toothed and the outer surface is drawn, and when the knockout member is actuated, the outer surface is necessarily restrained. , coining of the tooth profile of the material with the tooth profile of the mandrel is performed, and a tooth profile with good shape and accuracy can be obtained.

[Brief explanation of drawings]

Fig. 1 shows the main structure of a cold forging device according to the present invention. The left side of the center line is a sectional view showing the state after tooth formation on the inner surface of the material is completed, and the right side of the center line is a sectional view of the tooth shape on the inner surface of the material. A cross-sectional view showing the state after coining is completed, Fig. 2 is a cross-sectional view showing the main structure of a conventional cold forging device, and Fig. 3 is a view explaining the cross-sectional shape of the internal tooth profile of the rough material formed by the conventional method. It is. A...Cylindrical material 1...Dice 1a...
Upper inner surface 1b...Lower inner surface 2...Mandrel 2a...Tooth profile 5...Dice holder Patent applicant Toyota Motor Corporation Fang 1 Figure □ 8 Circular curve, j round survey material 1 ・Rice 1
0- Kamikuni inner surface 1b Lower inner surface 2
Mart Shiru 2a-tit
Shape 5・≦Fi 74 Suno L≦7− Fig. 2 Fig. 3

Claims (2)

[Claims] (1) A spline-shaped tooth profile is formed on the inner surface of the cylindrical material using the tooth profile of a mandrel, and the outer surface is subsequently drawn, and the tooth profile on the inner surface is coined with the tooth profile of the mandrel while the outer surface is restrained. A method for cold forging a product having a tooth profile characterized by the following. (2) forming the inner surface of the die slidably inserted into the die holder into an upper inner surface and a lower inner surface having a smaller diameter;
A cold forging device for a product having a tooth profile, characterized in that the upper inner surface is provided to correspond to the tooth profile of a mandrel.