JP2002178083A - Die for sizing stainless steel ring material after crf forming for increasing die life - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shape of a sizing die having a die life longer than a life of a conventional die by optimizing the die shape by using an approach part radius R of the approach part A of a round cross section and a bearing part length L of the sizing die as a parameter with use of a CAE(calculation acid engineering) analysis for increasing a die life. SOLUTION: In the sizing die 3 used for sizing a stainless steel ring material 1 after CRF(cold roll forming) forming, a cross sectional shape of a sizing face of the approach part A is formed to be a round shape, the approach part radius R as a radius of the round shape is stipulated to be 250-400 mm, the bearing part length L continuing the approach part A is stipulated to bed 3-8 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sizing die for sizing a stainless steel ring material after CRF forming (cold rolling).

[0002]

2. Description of the Related Art A stainless ring material after CRF usually has poor roundness and often does not satisfy the requirements. Therefore,
Using a sizing mold, the ring side face is elastically and plastically deformed to achieve the required roundness. This processing is called sizing processing. Although there is not much application in the past regarding the improvement of the mold life in the sizing mold used for the sizing process, the improvement of the mold life has been realized mainly by preventing seizure by improving lubrication. By the way, this sizing is similar to drawing from the viewpoint of plastic working. Prior art exists in the field of this drawing process. For example, there is a technique that can apply a vibration to a difficult-to-work material without causing seizure by applying vibration to the die in a radial direction by ultrasonic waves. In addition, there is a technique for preventing seizure by providing a taper angle in a region of a mold in contact with a workpiece.

[0003]

The life of a sizing die for sizing a stainless ring material by CRF is, for example, up to 380,000 for a bearing steel material (SUJ2), while it is a maximum for a stainless steel material (SUS430). 2
~ 50,000. Seizure is considered as a factor that shortens the life of the sizing mold. That is, SUJ2
Compared with the stainless steel, the stainless steel is seized more quickly with the sizing die, and thus has a significantly shorter life. In this regard, as a cause of the occurrence of seizure, a high load in a contact area between a stainless ring material to be processed and a sizing die can be cited. Therefore, in the present invention, in order to improve the life of the sizing die, CAE (calculation support technology) analysis is used to
By optimizing using the radius R of the approach portion of the circular approach portion A, which is a part of the mold for sizing, and the length L of the subsequent bearing portion as parameters, a sizing mold shape having a longer mold life than before is provided. It is to be.

[0004]

SUMMARY OF THE INVENTION According to the present invention, a material deformation analysis in an elasto-plastic region is performed by using CAE (Computational Assistance Technology) analysis, which has been remarkably advanced in recent years. The radius R of the sizing surface of the circular approach portion A and the length L of the bearing portion following the approach portion A are examined using the parameters as parameters, and the contact area between the stainless ring material 1 to be processed and the sizing mold 3 is determined. The mold load was studied. As the evaluation index, the product of the load in the normal direction 4 from the mold surface and the contact length, which is considered to have the most influence on the occurrence of seizure, was employed. By comparing the load and the contact length at each point on the obtained die surface, the optimum die shape capable of minimizing the die load was derived.

[0005] That is, a means of the present invention for solving the above-mentioned problems is to provide a sizing die used for sizing a stainless ring material after CRF molding, wherein the cross-sectional shape of the sizing surface of the approach portion A is circular, The radius R of the approach portion, which is the radius of the circle, is 250 to 400 m.
m, and the length L of the bearing portion following the approach portion A is specified to be 3 to 8 mm. That is, with respect to the sizing die 3 for sizing the stainless ring material 1 as the workpiece, the sizing surface of the approach portion A is circular, the radius of the approach portion R as the radius of the circle is 250 to 400 mm, and the approach portion A A sizing mold 3 having a mold part length L of 3 to 8 mm, which is excellent in mold life.

[0006] It is considered that the seizure is caused by the coupling between the contact length between the stainless ring material 1 to be processed and the sizing mold 3 and the load in the normal direction 4 of the sizing surface of the sizing mold 3. . Therefore, it is necessary to set upper and lower limits for the two parameters. Regarding the approach portion radius R, if the approach portion radius R is too long, the contact length increases, and if the approach portion radius R is too short, the processing increases too quickly and the load increases. Regarding the bearing portion length L, if the bearing portion length L is too long, the contact length similarly increases. If the bearing portion length L is short, springback occurs and good roundness cannot be obtained.

The upper and lower limits of the radius R of the approach portion and the upper limit of the length L of the bearing portion are values calculated from the results of the CAE analysis using the above-mentioned index. The lower limit of the bearing portion length L is a length necessary to obtain good roundness.
Approach part radius R is 150 to less than 250 mm, 400
Although the mold life is improved in the range of super to 450 mm, it is not very practical. The preferred approach radius R is between 250 and 400 mm as described above. Also, the length of the bearing part L
In the range of more than 8 to 10 mm, the mold life is similarly improved, but is not very practical. If it is less than 3 mm, springback occurs and good roundness cannot be obtained. A preferred bearing length L is 3 to 8 mm as described above.

Hereinafter, the operation of the present invention will be described.
FIG. 1 is an explanatory view showing a mold comprising a punch 2 and a sizing mold 3 of the present invention. The sizing step is to push the stainless ring material 1 into the sizing mold 3 by the punch 2 to thereby form the side surface 5 of the stainless ring material 1.
This is a process to obtain the roundness of the ring. The radius R of the approach portion and the length L of the bearing, which are the shape parameters of the sizing mold 3, are as shown in FIG.
As the evaluation index, the product of the load in the normal direction 4 of the sizing mold 3 and the contact length between the stainless ring material 1 as the workpiece and the sizing mold 3 is employed.

From the comparison between the evaluation index obtained in this way and the mold life obtained by actual machining, if the evaluation index in the contact area is 35 (N / mm) or less, the mold life is reduced. It turned out to be improved to 40,000. Therefore, the radius R of the approach portion is 150 to 600 mm, and the length L of the bearing portion is
Was subjected to CAE analysis in a range of 3 to 12 mm, and an evaluation index was calculated for a contact area between the stainless ring material 1 as a workpiece and the sizing mold 3. 2 and 3 show the results. 2 and 3, the evaluation index is 35.
The position of (N / mm) is indicated by a dotted line. From the test results on the actual machine, it was found that if this evaluation index was 35 (N / mm) or less, the mold life would be 40,000. Therefore, two parameters were set so as to be below the dotted line. There is a need to.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. The sizing process is performed cold, and a stainless ring material 1 is used as a material. The circularity of the ring is improved by pressing a stainless ring material 1 formed by CRF (cold rolling) into a sizing mold 3 with a punch 2. Both the punch 2 and the sizing die 3 are made of carbide tools. Regarding the shape parameters of the sizing mold 3, the approach portion radius R is 250 mm and the bearing portion length L is 3 mm.
And actually processed. As a result, while the life of the sizing mold was conventionally about 10,000 pieces, the result of the sizing mold 3 having the above shape was about 50,000 pieces.

[0011]

As described above, the present invention provides a CRF
The approach portion radius R of the approach portion A having a circular cross section of the sizing die used for sizing processing of the side surface of the subsequent stainless ring material is 250 to 400 mm, and the length L of the bearing portion following the approach portion A is 3 to 8 mm. By defining and optimizing the mold shape, the shot life of the mold can be extended several times, and as a result, the running cost during processing can be kept low, and unprecedented superior effects can be achieved. To play.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating a sizing mold.

FIG. 2 is a graph showing a relationship between an approach portion radius R and a load × contact length.

FIG. 3 is a graph showing a relationship between a bearing portion length L and a load × contact length.

[Explanation of symbols]

 Reference Signs List 1 stainless steel ring material 2 punch 3 sizing mold 4 normal direction 5 side A approach part L bearing part length R approach part radius

Claims (1)

[Claims] In a sizing die used for sizing a stainless ring material after CRF molding, a cross-sectional shape of a sizing surface of an approach portion is circular, and an approach portion radius R, which is a radius of the circle, is 250 to 250 mm.
A CR having a diameter of 400 mm and a length L of a bearing portion following the approach portion of 3 to 8 mm.
Mold for sizing stainless ring material after F forming.