JPH0332439A - Cold forging method for stepped hollow member - Google Patents

Abstract

PURPOSE:To obtain high working accuracy by working a deep part of a hole of a work to a hemispherical shape at the time of preforming, forming continuously an opening end of this hole and a connecting part of the hemispherical deep part, and setting a distance between this connecting part and a stepped part brought to upsetting the specific folds or above of the diameter of the hemispherical bottom part. CONSTITUTION:Preforming is executed by a cold forging device for preforming and on one end face of a work W brought to cutting, a hole 2 of prescribed depth is formed. Upsetting is executed by a cold forging device for upsetting and on the upper part of the work W, a tooth surface 3 is formed, a stepped part 3 is formed on its rear, and also, holes 3b, 3c are formed on the upper and the lower faces of the center in the axial direction. A distance L between a connecting line P of a deep part 2a of the hole 2 of the work W and the stepped part 3a is set to >=0.4 fold of the diameter D of the deep part 2a. Piercing is executed by a cold forging device for piercing and a wall thickness portion (t) between the holes 3a, 3b is brought to blanking and a hollow part 4 is formed. In such a way, high working accuracy is obtained and a stable product can be supplied continuously.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a step hollow member in which the dimensions of the hole during preforming before upsetting are set in consideration of workability during upsetting. Regarding a cold forging method.

[Problems to be solved by conventional technology and invention 1 As is well known, cold forging has a high material yield rate, product dimensional accuracy,
Not only does it have excellent surface finish and strength, but it is also highly productive, and is often used as a means of producing vehicle parts.

For example, when cold forging is used to form a stepped hollow member such as a side gear used in an automobile differential gear, the stepped part (tooth surface) is first formed by upsetting. Next, a hollow part (a part through which the DI shaft is pushed) is formed by punching.

In addition, in general, if the wall thickness during punching is relatively thick, it is not possible to punch the hole sufficiently, so in order to reduce the wall thickness, preforming is performed before the upsetting process. A hole is drilled to a specified depth.

However, if the hole depth during preforming exceeds a predetermined value, the balance between the centrifugal flow in which the material flows outward and the centripetal flow in which the material flows inward is lost, resulting in the formation of stepped Forging defects such as shrinkage and entrainment are more likely to occur in the parts.

For this reason, conventionally, as seen in Japanese Patent Publication No. 63-55381, processing such as faceting the end face of the workpiece has been carried out during preforming before upsetting. Due to the influence of material flow, variation in friction coefficient due to pre-lubrication treatment, variation in annealing hardness, etc., upsetting machining accuracy will vary, and as a result, hole punching precision will also vary, resulting in product defects. There is a problem with high rates.

[Objective of the Invention 1] The present invention has been made in view of the above circumstances, and is a stepped hollow material that can obtain high upsetting machining accuracy and punching machining accuracy and can continuously supply stable products. The object of the present invention is to provide a method for cold forging parts.

[Means and effects for solving the problem] The present invention preforms a hole of a certain depth in the axial end face of a workpiece cut to a predetermined size, and then presses the workpiece in the axial direction to form a step on the outer periphery. In a cold forging method for a stepped member in which a hollow part is formed by upsetting a part of the workpiece and then punching a hole in the thick part corresponding to the hole in the axial direction to form a hollow part, during preforming, The deep part is machined into a hemispherical shape, and the opening end of this hole and the tangential part of the hemispherical deep part are formed continuously, and the distance between this tangential part and the stepped part to be swaged is set as described above. It is 0.4 times or more the diameter of the hemispherical bottom.

Examples of tre Ming] Hereinafter, the present invention will be described in detail based on the drawings.

The drawings show an embodiment of the present invention; Fig. 1 is a process diagram showing the processing order of a workpiece by cold forging, Fig. 2 is a conceptual diagram illustrating the setting of hole dimensions during preforming, and Fig. 3 is Figure 4 is an enlarged view of the main parts of the cold forging equipment for preforming, Figure 4 is an enlarged view of the main parts of the cold forging equipment for upsetting, and Figure 5 is an enlarged view of the main parts of the cold forging equipment for punching. It is.

(Structure) The symbol W in the figure is a cylindrical workpiece, and as shown in Fig. 1, this workpiece undergoes (a) cutting process, (b) preforming process, (C) upsetting process, (d) Through the hole punching process, the side gear 1 of the differential gear device, which is an example of a stepped hollow member, is completed.

The cutting process is performed using a well-known shearing machine (not shown) to adjust the size of the workpiece W.

The preforming is performed in a cold forging device A for preforming, and a hole 2 of a predetermined depth is formed in one end surface of the workpiece W. The deep part 2a of this hole 2 is formed into a hemispherical shape with a diameter,
Further, a tangent line P at the end of the deep portion 2a and the opening end 2b of the hole 2 are tangent to each other.

Further, the upsetting process is performed using a cold R forming apparatus B for upsetting process, and a tooth surface 3 is formed on the upper part of the workpiece W, and a stepped part 3a is formed on the back surface of this tooth surface 3. ing. Further, holes 3b and 3c of a predetermined depth are formed in the upper and lower surfaces of the work W at the center in the axial direction.

As shown in FIG. 2, the distance between the tangential part P of the deep part 2a of the hole 2 of the workpiece W during the preforming and the stepped part 3a of the workpiece W during the upsetting process is as follows: Above deep part 2a
(L≧0.4)
0).

Further, the punching process is performed using a cold punching machine αC, and the thick part t between the holes 3b and 3C formed on the upper and lower surfaces of the upholstered workpiece W is punched out. A hollow portion 4 is formed.

FIG. 3 shows the configuration of the cold forging apparatus during preforming.

A reinforcing ring 12 is placed on the pressure receiving plate 11 of this cold forging device A for preforming, and a die 14 is attached to this reinforcing ring 12. Note that the reference numeral 15 is a mechanical lid bin that also serves as a pressure receiving plate.

Further, a punch 16 is provided oppositely above the die 14, and this punch 16 is vertically provided via a pressure receiving plate 17 to a punch holder 18 that is connected to a lifting device (not shown).

Further, the tip 16a of the punch 16 is formed into a hemispherical shape with a diameter, and the tangential line P at the hem and the base are connected by a tangential line, and the punch 16 forms the hole 2 in the workpiece W.

FIG. 4 shows the configuration of the cold RPJ forging device 8 for upsetting.

A die 23 is attached to a reinforcing ring 22 placed on a pressure receiving plate 21 on the fixed side of this cold forging device B for upsetting, a counter punch 24 is erected in the center of this die 23, and a counter punch 24 is installed at the lower end of the die 23. Epiphtabine 25 is abutted.

Further, a movable bonder 26 is provided above the die 23 and a die 27 is mounted around the bonder 26, and the punch 26 and the die 27 are connected to a lifting device (not shown) via a pressure receiving plate 29. The punch holder 30 is provided vertically.

The punch 26 and die 27 on the movable side and the die 2 on the fixed side
3. Using the counter punch 24, press the workpiece W in the wheel direction to form the tooth surface 3, the stepped portion 3a, and the holes 3b and 3c in the preformed workpiece W, respectively.

FIG. 5 shows the configuration of a cold-open forging device 1C for punching.

4! The placed die 32 is placed in V4 and 1. A hole punch 34 is provided above the die 32 and is vertically mounted on a movable punch holder (not shown).

The hollow portion 4 is formed by punching out the thick portion t between the holes 3b and 3c of the upholstered workpiece W using the hole punch 34.

(for production) Next, the operation of the embodiment with the above configuration will be explained.

(Pre-forming process) Cutting the machine into a predetermined size and attaching it to the die 14 of the device A until the cold # for pre-forming is completed, and then a punch holder 18 (not shown) is installed oppositely above the die 14. [1f
Drive fi to lower it.

Then, the tip 16a of the punch 16 vertically disposed on the punch holder 18 presses the end surface of the workpiece W set on the die 14, and the tip 16a of the punch 16 presses against the end surface of the workpiece W set in the die 14.
A hole 2 having a predetermined shape that follows the shape of a is formed.

(Upsetting process) Next, the preformed workpiece W is set in the die 23 of the cold forging apparatus 1B for upsetting.

Then, the punch 26 is vertically mounted on the punch holder 30 by moving a lifting device (not shown). When the die 27 is lowered, the punch 26 and the die 27 press the work W in the axial direction, and the work W is pushed by the punch 26. The die 27, the die 23 on the stationary side, and the counter punch 24 are pinched, and centrifugal flow and centripetal flow occur along the punches 26, 24 and the dies 27, 23, and the f! A stepped portion 3a on the surface and holes 3b and 3c are formed in a predetermined manner.

According to experiments, during preforming, the deep part 2a of the hole 2 of the workpiece W is machined into a hemispherical shape with a diameter, and the tangential part P of this deep part 2a and the opening end 2b are connected with a tangent, and the The stepped portion 3a and the tangential portion P formed by embedding processing.
A short break with the above! ! By setting the distance at least 0.4 times D, the balance between centrifugal flow and centripetal flow during upsetting is maintained, and it is not affected by variations in the friction coefficient due to the previous I11 sliding treatment and variations in annealing hardness. The upsetting shape becomes stable.

(Drilling process) After that, the upholstered workpiece W is
! 11 Set in the die 32 of the Jil making device C, and use the hole punch 34 to punch the upper and lower holes 3b of the workpiece W.

The hollow part 4 is formed by punching out the thick part t between 3C.

Since the upsetting shape of the workpiece W is stable, the dimensions of the hollow portion 4 formed by this punching process can also be approximately constant.

It should be noted that the present invention is not limited to the above-mentioned embodiments; for example, the stepped hollow member is not limited to the side gear of a differential gear device, and may be applied to any other member formed by cold forging.

Effects of the Invention As described above, according to the present invention, the deep part of the hole of the workpiece is machined into a hemispherical shape during preliminary forming, and the tangent between the opening end of the hole and the hemispherical deep part is and the gap between this tangential part and the stepped part to be upholstered is 0.4 times or more the diameter of the hemispherical bottom part,
The material flow balance during upsetting is maintained, high upsetting accuracy and hole punching accuracy can be obtained, and a stable product can be continuously supplied, among other excellent effects.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and Fig. 1 is a process diagram showing the processing order of a workpiece up to cold @, Fig. 2 is a conceptual diagram illustrating hole dimension setting during preforming, and Fig. 3 Figure 4 is an enlarged view of the main parts of the cold forging equipment for preforming, and Figure 4 is the cold forging equipment for upsetting.
FIG. 5 is an enlarged view of the main parts of the 1#1 forging device, and FIG. 5 is an enlarged view of the main parts of the cold forging device for punching holes. DESCRIPTION OF SYMBOLS 1... Stepped hollow member, 2... Hole, 2a... Deep part, 2b... Open end, 3a... Stepped part, 4... Hollow part, D... Diameter, L...Distance (between the tangential part and the stepped part), P...Tangential part, t...Thick part, W...Workpiece. Figure 3 Figure 4

Claims (1)

[Claims] A hole of a certain depth is preformed in the axial end face of a workpiece cut to a predetermined size, and then the workpiece is pressed in the axial direction to create a stepped portion on the outer periphery, and then the above-mentioned In a cold forging method for a stepped member in which a hollow part is formed by punching a thick part corresponding to a hole in the axial direction, during preforming, the deep part of the hole of the workpiece is machined into a hemispherical shape, and The opening end of this hole and the tangential part of the hemispherical deep part are formed continuously,
A method for cold forging a stepped hollow member, characterized in that the distance between this tangential portion and the stepped portion to be upholstered is 0.4 times or more the diameter of the hemispherical bottom portion.