JP3128208B2 - Manufacturing method of ring-shaped parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ring-shaped part formed by cold forging from a columnar material.

[0002]

2. Description of the Related Art When a ring-shaped part such as a bearing race is manufactured by forging, as shown in FIG. 9, a cylindrical blank A is usually cut by cutting or cutting a rod or wire (I). The blank A is subjected to preliminary upsetting (II) and (III), and the upper and lower end surfaces and the outer peripheral surface are corrected to form a cylindrical material B, which is then extruded (IV).
To form a cup-shaped part C. Next, the bottom D of the cup-shaped component C is punched out by a punching process (V) to form a ring-shaped member E, and further ironing (VI) and the like are performed. F is molded.

[0003]

Here, in the extrusion process (IV), the extrusion load is closely related to the cross-section reduction rate. As shown in FIG. 10, the extrusion load increases as the cross-section reduction rate increases. To increase. If the material to be forged is high in strength, and if the cross-section reduction rate is large, the stress acting on the extruded punch becomes close to or higher than the pressure resistance of the punch material (see FIG. 11), and the punch has a short service life or premature breakage. And extrusion becomes impossible. Therefore, there is a limit to the cross-sectional reduction rate that can be extruded.

[0004] The blank A is generally manufactured by cutting from a bar or a wire, but the volume of each blank A varies at the time of cutting. With conventional technology,
Extrusion (IV) determines the length of the ring-shaped member E
However, the columnar material B during the extrusion process is usually
Since the one end face B ′ side is a free end, the influence of the variation in the volume of the blank A appears on the free end face C ′ side of the cup-shaped component C as a margin. As a result, the length of the ring-shaped part F which is a finished product varies, and this variation is considerably large in a ring-shaped part having a large sectional reduction rate.

Further, at the time of the extrusion (IV) of the columnar material B, one end face B 'side is not restrained by the tool at all, so that the natural deformation state at the time of the extrusion remains in the ring-shaped member E as it is, The end face E ′ cannot be formed into a required shape.

On the other hand, the end face E ′ is ironed (V
At the time of ironing (VI), a tool is forcibly applied to the end face E ', or the end face E' of the ring-shaped member E is fixed in order to obtain the end face F 'having a required shape by performing correction at the time of I). Even if a tool is forcibly applied to the free end face B 'of the cylindrical material B during the extrusion (IV) in order to form the end face shape neatly, the cup-shaped part C or the ring-shaped member E due to the variation in the volume of the blank A Insufficient restraint of the tool due to the variation in the length of the tool, or conversely, the material becomes too full in the tool and excessive force acts on the tool,
There is a possibility that troubles such as early breakage of the tool may occur.

Further, in the punching process (V) for punching the bottom D of the cup-shaped part C, if the bottom D is thin,
As shown in FIG. 12, the punch F side at the time of punching,
Cracks H are immediately generated near the corners of the push punch G on the opposite side, and a large fracture surface I is generated on the inner peripheral surface side of the ring-shaped member E, thereby deteriorating the inner diameter dimensional accuracy. On the other hand, when the thickness of the bottom portion D is increased to prevent the occurrence of the fracture surface I, there is a problem that the volume of the swarf J increases and the material yield during forging deteriorates.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and is intended to provide a cup-shaped or ring-shaped material having a large cross-sectional reduction ratio even when the strength of the material is high. The purpose of the present invention is to provide a tool that can be formed into a part and that can improve the life of tools such as an extrusion punch. A pre-extrusion process for forming a first cup-shaped part having
Of the cup-shaped part in the vicinity of the bottom is pressed against the second cup-shaped part having an inner diameter smaller than the inner diameter of the first cup-shaped part from the vicinity of the bottom to the open end having the same inner diameter as the inner diameter of the ring-shaped part. A ring, wherein the main extrusion process is performed, and a punching process is performed in which a bottom of the second cup-shaped component is punched into the same size as the inner diameter of the ring-shaped component to form a ring-shaped component. In a method of manufacturing a shaped part.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in FIGS. 1 to 8. FIG. 1 shows the processing steps according to the method of the present invention. processing,
(II) is pre-extrusion processing, (III) is main extrusion processing, (I
V) is each step of the punching process. In the case where the cylindrical material 1 can be obtained by cutting without cutting or deforming a wire or a bar, the above-described process for correcting the end face and the outer peripheral face is performed. It is not necessary to go through the pre-upsetting step (I).

Next, in the pre-extrusion processing step (II) of the cylindrical material 1, as shown in FIG. 2, the pre-extrusion punch 2 has an inner diameter φb smaller than the inner diameter φa of the target ring-shaped part. Extrusion into the first cup-shaped part 3. At this time, since the cross-sectional reduction rate is smaller than when extruding to the inner diameter dimension φa of the same size as the inner diameter dimension of the target ring-shaped part, the deformation rate and the degree of constraint of the columnar material 1 are reduced, and the pre-extrusion processing is performed. The molding load at the time becomes small.

In the next main extrusion step (III), the first cup-shaped part 3 obtained in the pre-extrusion processing step (II) is extruded as shown in FIGS.
Extrusion molding. The extrusion punch 4 is for forming an inner diameter φa of the same size as the inner diameter of the target ring-shaped part, and has a cylindrical part (large diameter part) 5 having an outer shape for forming the inner diameter of the ring-shaped part; At the tip thereof, a convex portion (small diameter portion) 6 having an outer diameter φc smaller than the inner diameter size φb of the first cup-shaped component 3 formed in the pre-extrusion process (II) is provided. The portion 6 and the distal end surface and the side surface are smoothly connected to each other by R, and have a distal end shape.

In the main extrusion step (III), the second cup-shaped part 7 is formed by extrusion so as to have the inner diameter of the ring-shaped part. In this case, the preliminary extrusion step (II) of the preceding step is performed. The inner diameter side of the first cup-shaped part 3 formed by the above is further extruded by the extrusion punch 4. for that reason,
As shown in FIG. 3, most of the first cup-shaped part 3 on the inner diameter side is already a gap S, and since there is no material on the tip end surface 4A side of the extrusion punch 4, the main extrusion processing is performed. In the step (III), the cross-sectional reduction rate is substantially reduced. Therefore, the forming load at this time is considerably smaller than when the target is extruded to the inner diameter φa of the target ring-shaped part at a time, and is much smaller than the conventional extrusion process.

As described above, in the present invention, the extrusion is finished to the target ring-shaped part dimensions by the two extrusion processes of the pre-extrusion process (II) and the main extrusion process (III). The extrusion load is dispersed in each processing, and the load in each processing step is reduced. In addition, since the extrusion punch 4 has the above-described tip shape, as shown by the arrow in FIG. 4, most of the material located near the tip surface 4A of the extrusion punch 4 smoothly moves in the extrusion direction of the peripheral wall portion. Flow, main extrusion process (III)
Increase of the load during the extrusion in the step can be prevented. Therefore,
Even when the strength of the material is high, a cup-shaped or ring-shaped part having a large cross-sectional reduction rate can be formed, and the life of the tools such as the extrusion punch 4 is improved.

Here, in the main extrusion step (III), the extrusion punch P having the conventional structure as shown in FIG. 5, that is, the tip surface is made flat or a cone having a large tip angle, and the tip surface and the side surface are connected. When a tip having a shape connected at the R portion is used, the first shape formed in the pre-extrusion processing step (II) is used.
Since the inner diameter of the cup-shaped part 3 is smaller than the outer diameter of the extruded punch P, most of the material located on the distal end surface of the extruded punch P moves as the punched end surface moves and the bottom 3A
Extruded to the side. As a result, the indentation punch 10
The material 3A 'extruded with the movement of the punch P is sandwiched between the tip end surface of the extrusion punch P and the bottom 3A and increases the molding load. Can not achieve.

In the present invention, the main extrusion process (I
In (II), before the distal end face 4A of the extrusion punch 4 comes into contact with the bottom 3A of the first cup-shaped component 3, as shown in FIGS. An end-face restraining tool 8 is arranged below the die 9 so as to be in contact with the end face 3B, and upper and lower end faces of the first cup-shaped component 3 are restrained by a pushing punch 10 and the end face restraining tool 8, respectively. In this case, it is necessary to provide a kick pin at the center of the extrusion punch 4 so as to be slidable.

When the lower end surface 3B comes into contact with the end surface restraining tool 8, the end surface 3B cannot move any more, and the flow of the material in the extrusion direction stops. In this case, in the pre-extrusion step (II) of the previous step, the inner diameter side of the first cup-shaped part 3 is in a state of no material, and the tip end face 4A of the extrusion punch 4
And a gap S between the first cup-shaped part 3 and the bottom 3A.
Therefore, even if the lower end face 3B of the first cup-shaped component 3 is restrained by the end face restraining tool 8, the excess portion of the material moves to the gap S as shown by the arrow in FIG. . Therefore, even after the end face 3B of the extruded first cup-shaped part 3 comes into contact with the end face restraining tool 8, the forming load does not increase abruptly, and the pushing punch 10 pushes the material to the regular position. Thus, the second cup-shaped part 7 can be formed.

Since the length of the second cup-shaped part 7 corresponding to the ring portion after punching is restricted by the distance between the indenting punch 10 and the end face restraining tool 8, one cup is formed. The difference between the maximum and minimum lengths of the cups is reduced, and the variation in the length of each cup is also reduced. As a result, the difference between the maximum length and the minimum length in the ring obtained in the next punching step (IV) was about 0.3 mm at maximum in the prior art, but at maximum in the ring of the present invention. 0.15
mm or less. Also, since the increase in load can be suppressed,
Tool life does not deteriorate.

In the main extrusion step (III), the end face 3B of the extruded first cup-shaped part 3 is contacted with the end face restraining tool 8 to increase the load. A surface (portion C) between the large diameter portion 5 for forming the inside diameter and the small diameter portion 6 smaller than the inside diameter of the first cup-shaped part 3 extruded in the preliminary extrusion step (II);
Since the load is shared by both the end face restraining tool 8 (D part) arranged on the B side, the tool life of each tool does not decrease.

Further, in the main extrusion step (III), FIG.
As shown in FIG. 7, when the shape of the end face restraining tool 8 disposed on the end face 3B side of the first cup-shaped component 3 to be extruded is made appropriate, at least one end face 11A of the ring-shaped component 11 becomes flat. A defined end face shape having a flat or flat part and a subsequent arc or slope towards the inner and outer diameter surfaces is obtained, without subsequent post-processing.

Next, in the punching step (IV), the bottom 7A of the second cup-shaped part 7 formed in the main extrusion step (III) is punched, and a ring-shaped part 1 as a finished product is obtained.
This is a process for molding into 1. In the step of punching the bottom 7A of the second cup-shaped component 7, if the bottom 7A is thin,
As shown in FIGS. 8 and 12, cracks are immediately generated from near the corners of both the punch 12 and the punch 13 on the opposite side during punching. A large fractured surface is generated and the dimensional accuracy of the inner diameter is deteriorated. On the other hand, the bottom 7
When A is thickened, the volume of the swarf increases, and the material yield during forging deteriorates.

In the present invention, the thickness of the bottom 3A of the cup-shaped part 3 is reduced to the extrusion limit in the pre-extrusion processing step (II). Next, re-extrusion is performed in the main extrusion processing step (III), and the substantial punching length H is increased at the step between the large diameter portion 5 and the small diameter portion 6 of the extrusion punch 4 (see FIG. 8). )
Therefore, even if the thickness of the bottom 3A of the cup-shaped part 3 is reduced to the extrusion limit in the pre-extrusion processing step (II), the same effect as that obtained by increasing the thickness of the bottom to prevent a fracture surface can be obtained.

Thus, in the punching step (IV),
Punching punch 12 side and pushing punch 13 on the opposite side
The generation of early cracks from the vicinity of the corners on both sides can be suppressed, and a large fractured surface does not occur on the inner diameter side of the ring-shaped component 11, thereby improving the inner diameter dimensional accuracy. In addition, since the thickness of the bottom 3A of the cup-shaped part 3 can be reduced to the extrusion limit in the pre-extrusion step (II), the volume of the scrap of the bottom 3A can be reduced, and the yield of the material can be improved.

[0023]

Since the present invention has the above configuration,
(1) Even when the strength of the material is high, it is possible to mold a cup-shaped or ring-shaped part having a large cross-sectional reduction rate,
In addition, the life of tools such as an extrusion punch is improved. (2) Even if the end faces of the cup-shaped part are restrained by tools during the main extrusion, the forming load does not increase sharply, and the indentation punch can push the material to the regular position, so that one ring The difference between the maximum and the minimum of the inside length is reduced, and the variation in the length of each ring is also reduced.
(3) Between the large-diameter portion forming the inner diameter of the product of the extrusion punch and the small-diameter portion smaller than the inner diameter of the pre-extruded cup-shaped component, with respect to the increase in load after the both end surfaces of the cup-shaped component are restrained by the tool. Since the load is shared by both the surface of the material to be extruded and the tool disposed on the end face side of the material to be extruded, the life of each tool does not decrease.

(4) When the shape of the end face restraining tool disposed on the end face side of the material to be extruded is made appropriate, at least one end face of the product is directed to a flat portion or a flat portion, and subsequently to the inner and outer diameter surfaces. It is possible to obtain a product having a predetermined end face shape having an arc portion or an inclined portion. (5) Even if the thickness of the bottom of the cup-shaped part is reduced to the extrusion limit by the pre-extrusion processing, the substantial punching length can be increased, so that an early crack from the vicinity of the punching punch and the punching punch on the opposite surface at the time of punching. Can be suppressed. Therefore,
A large fracture surface does not occur on the inner diameter side of the ring-shaped part, and the accuracy of the inner diameter dimension is improved. (6) Compared with the ring-shaped parts obtained by the conventional forging technology, the length and dimensional accuracy are significantly improved. At the same time, a predetermined shape can be obtained while at least one of the end faces remains forged. Man-hours required for grinding and the like can be reduced.

(7) In the pre-extrusion step, the thickness of the bottom can be reduced to the extrusion limit, so that the volume of the bottom scrap can be reduced and the material yield can be improved. (8) If the main extrusion is performed with the extrusion punch having the tip shape according to the present invention, much of the material located on the tip face of the punch flows smoothly in the extrusion direction of the side wall without accumulating at the tip of the punch, and the load of the load is reduced. Increase can be prevented. (9) Even if both end faces of the cup-shaped part are constrained by tools, both the tool life is not reduced because the load is shared by both the end face constraining tool disposed on the end face side to be extruded and the extruding punch. . There are various effects.

[Brief description of the drawings]

FIG. 1 is a view showing a processing step of a ring-shaped part according to the method of the present invention.

FIG. 2 is a cross-sectional view at the end of pre-extrusion processing.

FIG. 3 is a cross-sectional view at the start of main extrusion.

FIG. 4 is a partial cross-sectional view illustrating the operation during the main extrusion.

FIG. 5 is a cross-sectional view during and after extrusion processing by a conventional apparatus.

FIG. 6 is a cross-sectional view during and after main extrusion according to the present invention.

FIG. 7 is a cross-sectional view immediately before and at the end of the main extrusion according to the present invention.

FIG. 8 is a cross-sectional view just before the start of the punching process and during the punching process.

FIG. 9 is a view showing a processing step of a conventional ring-shaped part.

FIG. 10 is a graph showing an example of a cross-sectional reduction rate and a surface pressure applied to a pressing punch.

FIG. 11 is a graph showing an example of material hardness and surface pressure applied to an extrusion punch.

FIG. 12 is an explanatory view showing a broken state at the time of bottom punching of a cup-shaped component.

[Explanation of symbols]

 Reference Signs List 1 cylindrical material 2 pre-extrusion punch 3 first cup-shaped component 3A bottom 3B end surface 4 extrusion punch 4A distal end surface 5 large-diameter portion 6 small-diameter portion 7 second cup-shaped component 7A bottom 8 end-face restraining tool 9 die 10 push-in punch DESCRIPTION OF SYMBOLS 11 Ring-shaped component 11A End surface 12 Punching punch 13 Pushing punch

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaaki Odone 3- 10-15 Yawata-cho, Shinminato-shi, Toyama Pref. Japan High Frequency Steel Industry Co., Ltd. Toyama Works (72) Inventor Mitsuaki Nakata Ishimaru 708, Takaoka-shi, Toyama No. 16 Inside Nukei Shiatsu Co., Ltd. (72) Inventor Hiroshi Okamoto 16 at 708 Ishimaru, Takaoka City, Toyama Prefecture Inside Nukei Shiatsu Co., Ltd. (72) Inventor Katsushi Irizawa 16 at 708 Ishimaru, Takaoka City, Toyama Prefecture (56) References JP-A-8-267173 (JP, A) JP-A-1-89833 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21K 21/06 B21D 28 / 00,53 / 16 B21J 5/06

Claims (3)

(57) [Claims] 1. A pre-extrusion process for forming a cylindrical material into a first cup-shaped part having an inner diameter smaller than the inner diameter of a ring-shaped part, and the first cup-shaped part is provided with a first cup near the bottom. A main extrusion step of extruding an inner diameter smaller than the inner diameter of the ring-shaped part into a second cup-shaped part having the same inner diameter as the inner diameter of the ring-shaped part from the vicinity of the bottom to the open end; A step of punching the bottom of the part with the same size as the inner diameter of the ring-shaped part to form a ring-shaped part. 2. In a main extrusion step of extruding the first cup-shaped part into a second cup-shaped part, before a tip end face of an extrusion punch comes into contact with a bottom part of the first cup-shaped part, 2. The method for producing a ring-shaped component according to claim 1, wherein the end face of the cup-shaped component is restrained and extruded. 3. A large-diameter portion having an outer diameter for forming an inner diameter of a ring-shaped component, and said first cup-shaped portion is provided at a tip of said large-diameter portion in the main extrusion process of the manufacturing method according to claim 1. A small diameter portion having an outer diameter smaller than the inner diameter of the component,
A method of manufacturing a ring-shaped component, comprising extruding the large-diameter portion, the small-diameter portion, and the tip surface and the side surface thereof with an extruding punch having a tip shape smoothly connected to each other by an arc.