JPH0679393A - Forging equipment - Google Patents

Abstract

(57) [Summary] [Object] To provide a forging device capable of cold forging a tooth profile of an internal tooth with high precision without damaging the teeth of a mandrel. A ring-shaped die (2) is provided with a land portion (2b) projecting to the inner peripheral side, and a mandrel (1) having a helical tooth profile is provided on the inner peripheral side of the die (2) so as to be movable in the mandrel axial direction and around the mandrel shaft center. A forging device that is rotatably supported on. When the material 9 is moved inward by the land portion 2b and is pushed into the tooth profile of the mandrel 1, the teeth of the mandrel 1 receive force from both sides, so that the bending stress is reduced. Further, since the teeth of the material are always guided by the tooth profile of the mandrel 1 during molding, the tooth profile is molded with high accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forging apparatus for cold forging tooth profile parts, which can be used for cold forging helical gears having internal teeth.

[0002]

2. Description of the Related Art Planetary ring gears for automatic transmissions of automobiles are helical gears having internal teeth. The internal gear helical gear 12 shown in FIG. 5 is conventionally manufactured by cutting with a helical broach. FIG. 6 shows the internal gear helical gear 16 of FIG.
Shows a die device in the case of forming an annular material by cold forging. That is, the mandrel 14 having a toothed portion is fixed in the die 13, and the die 1 is
3 shows the case where the material 16 is pushed into the forming space between the mandrel 14 and the mandrel 14 and the helical tooth profile is formed on the inner peripheral side of the material by cold forging.

[0003]

However, the conventional method has the following problems. Cutting with a helical broach requires higher processing costs and longer processing time than forming. In addition, since the cutting tool life is short and the cutting tool cost is high, the cost of consumables is also high. Further, in the cold forging process, when the material is pushed into the forming space, an excessive load is applied from the material to the tooth profile of the fixed mandrel, and if the tooth height is high, the mold tooth profile is damaged. Further, it is difficult to secure the accuracy of the tooth profile of the product.

The reason why these problems occur in cold forging is as follows. In the case of the cold forging die configuration shown in FIG. 6, when the material 16 is pushed downward by the sleeve punch 15, the material of the material 16 hits the upper flank of the twisted tooth profile of the mandrel 14. ,
Causes large bending stress on teeth. As the tooth height increases, the bending stress also increases and the tooth breaks from the root, so cold forging cannot be applied to the molding of tooth profiles with high teeth.

Further, as shown in FIG. 8, when the molded tooth profile of the material 16 is pushed downward past the teeth of the mandrel 14, the excess portion is restrained by the teeth of the mandrel 14. Since it is not available, accuracy cannot be secured. Generally, the land width of the mandrel tooth profile is usually 3 to 5 mm in order to reduce processing pressure and frictional resistance during extrusion processing.
However, it is not possible to maintain the accuracy up to the passing part.

An object of the present invention is to provide an internal tooth helical toothed part,
An object of the present invention is to provide a forging device capable of cold-forging a tooth profile with high accuracy without damaging the tooth profile generation part of the die.

[0007]

The above object can be achieved by the following forging device according to the present invention. That is, an annular die is pushed into a forming space formed between an annular die, a mandrel having a tooth forming profile formed in a portion to be inserted into the die, and a molding space formed between the die and the tooth forming profile of the mandrel. In a forging device having a sleeve punch, a land portion protruding toward the inner peripheral side is formed in the die, the tooth profile of the tooth forming profile of the mandrel is a helical tooth profile, and the mandrel is movable in the mandrel axial direction and A forging device rotatably supported around the mandrel axis.

[0008]

In the forging device of the present invention, the material is pushed into the forming space by the sleeve punch, brought closer to the inner peripheral side by the land portion of the die, and bites into the tooth profile portion of the mandrel. Since the mandrel is movable in the axial direction and the rotating direction, the tooth profile of the mandrel is formed on the material while a load is applied to the tooth surfaces of the mandrel (the upper and lower surfaces of the twisted teeth). Therefore, an excessive bending stress is not generated in the tooth profile of the mandrel as compared with the conventional case where the load is mainly applied only from the upper tooth surface. That is, it is possible to perform cold forging of high carbon steel parts without damaging the mandrel.

Further, since the tooth profile of the material bites into the tooth trace of the mandrel and is always constrained by the tooth profile of the mandrel, a highly accurate tooth profile part can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the forging device according to the present invention will be described below with reference to FIGS. As shown in FIG. 1, the forging device according to the embodiment of the present invention has a die 2, a mandrel 1, and a sleeve punch 4. The forging device further includes a sleeve knockout 3 and a knockout pin 5
And has a spacer 6 and a spring 7.

The die 2 is an annular fixing member, and its axis is oriented in the vertical direction. An annular material 8 is inserted into the die 2. The upper part 2a of the die 2 has a large inner diameter into which the material 8 can be inserted, and has a land portion 2b having an inner diameter smaller than the outer diameter of the material 8 in the middle, and the lower portion 2c below the land portion 2b has a slightly larger diameter than the land portion 2b. Has been done. When the material 8 is pushed from the upper portion 2a of the die 2 toward the land portion 2b, the material 8 is squeezed toward the inner peripheral side by the land portion 2b and is pressed to form the material 9 (the material 8 before molding is The material 9 is used in the middle or after molding.

The mandrel 1 comprises a tooth bearing profile 1a having a helical tooth profile on the outer periphery, a holder 1b for supporting the tooth profile profile 1a from below, and a thrust bearing comprising a spherical seat for pressing the tooth profile profile 1a from above. 1c and thrust bearing 1c
Is formed of a bolt 1d which is inserted into the tooth-forming shaped portion 1a and screwed into the holder 1b. However, the tooth forming portion 1a
Is around the axis with respect to the holder 1b and the bolt 1d,
It is set to be rotatable.

The mandrel 1 is inserted inside the die 2 so that the tooth forming shape portion 1a comes inside the land portion 2b of the die 2. Further, the mandrel 1 is movably supported from below by a spring 7, and when pushed down together with the material 9 by the sleeve punch 4 at the time of molding, the mandrel 1 is bent downwards with respect to the die 2 with the bending of the spring 7. It can be moved relatively.

Tooth forming profile 1a of mandrel 1 and die 2
The annular space between and is the tooth forming feature. The outer diameter of the tooth forming portion is narrowed at the land portion 2b. Therefore, when the material 9 is pushed downward, the material 9 is pushed toward the inner peripheral side by the land portion 2b, and the material 9 is hard to be inserted into the tooth profile of the tooth forming profile 1a of the mandrel 1, and the tooth profile of the internal teeth is formed in the material 9.

Above the tooth forming portion, the sleeve punch 4 is provided.
Is provided so that it can move up and down. When the sleeve punch 4 is pushed downward by the upper ram of the press, the sleeve punch 4
Pushes the material 9 downward. When the upper ram is raised, the sleeve punch 4 is hooked and lifted by the punch holder 11 fixed to the upper ram.

As shown in FIG. 2, a sleeve knockout 3 for extruding the tooth profile part 9 after molding is provided below the tooth forming profile. Sleeve knockout 3
When the knockout pin 5 is pushed upward, the knockout pin 5 is pushed up via the spacer 10 to push up the molded product 9. Further, the mandrel 1 has a brim 1e formed in the vicinity of the lower end thereof so that the mandrel 1 is engaged with the stepped portion 6a formed on the fixed spacer 6 so that upward movement of a certain value or more is restricted. It has become.

FIG. 3 shows the annular blank 8 before forming. Figure 4
Shows a material state in which the helical tooth profile of the internal teeth is formed by using the apparatus shown in FIGS. 1 and 2.

Next, the operation will be described. Ring material 8 in Figure 3
Is passed through the mandrel 1 and inserted into the tooth forming profile in the die 2. Next, the upper ram is lowered. The sleeve punch 4 hits the end surface of the material 8 and the end surface of the mandrel 1, and pushes down each to start extrusion of the material outer diameter (FIG. 1).
Of the right half before molding).

The outer diameter of the material is reduced, the material flows to the inner diameter side of the material, and the helical tooth profile is successively formed by the tooth forming portion 1a having the helical tooth profile. At this time, mandrel 1
Slides downward together with the material 9 that is being formed, and reduces the stress load on the tooth profile 1a. This downward sliding creates a gap between the sleeve punch 4 and the mandrel 1 (see the left half of FIG. 1). The guide portion length of the sleeve punch 4 is set so that the mandrel tooth forming portion 1a can be guided by the sleeve punch inner diameter 4a even after the completion of the forming. In this case, if not guided, the material flows to the end surface of the tooth forming profile 1a, and the end surface of the tooth forming profile 1a is damaged.

When the ram reaches the bottom dead center, the extrusion of the outer diameter of the material is completed, and the shaping of the internal teeth of the helical tooth is also completed (see the state after the shaping in the left half of FIG. 1).

The product is taken out as follows. Raise the ram as shown in FIG. After the ram has moved up, the knockout pin 5 is moved up, so that the sleeve knockout 3 pushes up the material 9 via the spacer 10. The mandrel 1 rises with the material 9, and when the brim 9a of the material 9 is pulled out from the die 2, the brim 1e of the mandrel hits the stepped portion 6a of the spacer 6 and the upward movement of the mandrel 1 is fixed. (See the knockout process in Figure 2).

Further, as the sleeve knockout 3 rises, the material 9 is extracted from the tooth forming profile 1a,
The knockout is completed (see the state after knockout in FIG. 2). At this time, the tooth forming portion 1a of the mandrel rotates in the twisting direction. The stress load on the tooth profile of the tooth forming profile is small. In addition, since the thrust bearing 1c is provided between the bolt 1d and the tooth forming portion 1a, the rotation is easy and seizure is prevented.

[0023]

According to the present invention, the following effects are obtained. I. With the mandrel movable in the axial and rotational directions, the material can be brought closer to the mandrel side at the land of the die, so the load is applied from both sides of the teeth of the mandrel's tooth forming part, and the molded teeth of the mandrel are excessive. No bending stress is generated. Therefore, it is possible to prevent the mandrel from being damaged. B. Since the molded tooth profile of the material is always constrained by the tooth profile of the mandrel, a product with high tooth profile accuracy can be obtained. C. Since the helical tooth profile can be processed by cold forging, the strength of the tooth profile can be increased without cutting the material flow line as in the cutting process. D. By cold forging, the processing time can be greatly shortened and the cost can be reduced significantly.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state before and after forming of a forging device according to an embodiment of the present invention.

2A and 2B are cross-sectional views showing a part of the forging device of FIG. 1 during and after knocking out a material after forging.

FIG. 3 is a cross-sectional view of a material before forging.

FIG. 4 is a cross-sectional view of a material after forging and a product after cutting.

FIG. 5 is a cross-sectional view of a tooth profile part having a helical tooth profile formed by cutting.

FIG. 6 is a cross-sectional view of a conventional forging device for cold forging gear parts.

7 is a cross-sectional view of a tooth profile part that has been cold forged by the apparatus of FIG.

8 is a partial cross-sectional view of the apparatus of FIG. 6 in which the material tooth profile passes through the tooth profile of the mandrel.

[Explanation of symbols]

 1 Mandrel 1a Tooth forming part 2 Die 2b Land part 3 Sleeve knockout 4 Sleeve punch 5 Knockout pin 6 Spacer 7 Spring 8 Material before molding 9 Material in the middle of molding and after molding

Claims (1)

[Claims] 1. An annular material in a molding space formed between an annular die, a mandrel having a tooth forming profile formed in a portion to be inserted into the die, and a molding space formed between the die and the tooth forming profile of the mandrel. In a forging device having a sleeve punch for pushing in, a land portion projecting to the inner peripheral side is formed in the die, the tooth profile of the tooth forming profile of the mandrel is a helical tooth profile, and the mandrel is moved in the axial direction of the mandrel. A forging device, which is supported so as to be rotatable about the mandrel axis.