JP2012223798A - Method of manufacturing ring-like preformed material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cold-work a ring-shaped material before cold forging that reduces the processing cost by sizing the outer diameter instead of turning the outer diameter surface to improve the yield and productivity. A method for obtaining a bearing shape material from a ring-shaped material before cold forging is provided.
A cold forging material for an outer race in a method for processing an end surface and an inner diameter of a ring-shaped material for cold forging into a cold forging material for an outer race by simultaneously forging by cold forging. Prior to cold forging, the outer diameter of the ring-shaped material is sized, and the inner surface is turned to cold-process the ring-shaped material before cold forging. This ring-shaped material before cold forging A method for processing a ring-shaped material, in which the clearance between the forging die and the ring-shaped material before cold forging is kept constant and the bearing material is processed by cold forging.
[Selection] Figure 1

Description

  The invention of the present application relates to a method for manufacturing a ring-shaped material for a bearing race into a bearing shape material by cold forging, and in particular, the outer diameter sizing (hereinafter referred to as “outer diameter sizing”) of the ring-shaped material before cold forging. This relates to a method of manufacturing a ring-shaped material sized outside diameter into a bearing shape material by cold forging.

  As a conventional method of manufacturing a bearing material, when manufacturing a bearing material, an outer ring-shaped material is used to maintain a constant clearance between the forging die and the ring-shaped material before cold forging. It is necessary to turn the radial surface in advance to improve the accuracy of the dimensions and roundness, which greatly reduces the material yield. In addition, after turning the ring-shaped material before cold forging, it becomes a problem if scratches or other scratches are generated in the outer diameter portion, and therefore it is necessary to process them one by one in the manufacturing process. For this reason, since it is not possible to process a plurality of pieces at a time, productivity is lowered and equipment costs are increased.

  Conventionally, as a method of manufacturing a bearing race, in a method of manufacturing a hollow material manufactured from a bearing steel pipe by cold forging, the bearing steel pipe is cut at a predetermined width perpendicular to the center axis of the bearing steel pipe. A ring is manufactured, and the inner diameter surface and outer diameter surface of the cutting ring are respectively turned to predetermined diameters to obtain a material before forging, and cold forging is performed while constraining the inner diameter surface of the material before forging. The outer race and the inner race of the bearing race are manufactured by separating the outer race into the outer race and the inner race, and turning these predetermined surfaces while leaving the other surfaces forged. Has been proposed (see, for example, Patent Document 1).

  Furthermore, as a method of manufacturing a bearing outer ring shape material, a method of manufacturing a single bearing outer ring shape material by cold forging a hollow blank made from a seamless steel pipe such as bearing steel into a ring. After cutting, the inner and outer diameter surfaces of the resulting ring are turned, and these surfaces are shot blasted and lubricated to form ring-shaped blanks, which are then cold ironed by cold forging. A method for forming a bearing outer ring shape material has been proposed (see, for example, Patent Document 2).

  However, in these methods of Patent Document 1 and Patent Document 2, as in the above-described conventional method, the yield is lowered to improve the accuracy of the ring-shaped material and the roundness, and the outer diameter surface is further reduced. There was a problem that scratches were generated.

JP 2007-130673 A JP 2009-277331 A

  Therefore, the problem to be solved by the present invention is a processing method for solving the above-mentioned conventional problems, and by introducing a method for sizing the outer diameter instead of turning the outer diameter surface, Using a ring-shaped material before cold forging manufactured by this method and a cold-forged ring-shaped material manufactured by this method, which achieves a reduction in processing cost by improving yield and productivity. It is to provide a method for producing a bearing blank by cold forging.

  The means of the present invention for solving the above-mentioned problems is the method according to claim 1, wherein the end face and the inner diameter portion of the ring-shaped material are simultaneously reduced by cold forging and processed into a cold forged raw material of the outer race. Is the method. In this method, the outer diameter of the ring-shaped material is first sized prior to the cold forging that is processed into the cold forging material of the outer race. Next, this is a method for producing a ring-shaped material, in which the inner surface of the ring-shaped material sized outside is turned to obtain a ring-shaped material for cold forging.

  According to the second aspect of the present invention, the ring-shaped material provided for the cold forging manufactured by the processing method according to the first aspect of the present invention is further maintained with a constant clearance between the forging die and the ring-shaped material before the cold forging. This is a method for producing a bearing shape material, in which cold forging is performed to obtain a bearing shape material.

  By sizing the outer diameter by the means of claim 1 above, the dimensional accuracy of the outer diameter of the material before cold forging can be improved without improving the hardness of the outer diameter surface of the material before cold forging. The outer diameter turning can be omitted, and the dimensional change of the outer diameter and inner diameter of the material before cold forging by the sizing process is approximately the same as the CAE analysis value obtained by the computer. The invention of the present application has excellent effects, such as a small increase in hardness due to the cost and no occurrence of cracks due to an increase in hardness due to the outer diameter sizing.

It is a trial drawing which shows the example of a sizing process, (a) is a ring-shaped raw material (blank), (b) is a raw material before cold forging, (c) shows a cold forging product. The schematic diagram of an outer diameter sizing is shown. The schematic diagram of cold forging is shown. Schematic diagram showing the need to improve the roundness of the ring-shaped material (blank) by sizing the outer diameter, (a) is a case where the outer diameter of the blank is not displaced and smaller than the inner diameter of the die, and no improvement is required (b ) Shows a case where the blank has a deviation in the outer diameter and needs to be improved more than the inner diameter of the die. It is a graph which shows the hardness distribution of the longitudinal direction position of the ring-shaped raw material surface before and after the outer diameter sizing with a sizing allowance of 0.8 mm, (a) before the outer diameter sizing and (b) after the outer diameter sizing. It is a graph which shows each dimensional change of the outer diameter of a ring-shaped raw material which carried out sizing of 0.8 mm as sizing allowance, an internal diameter, and the width by the actual machine, and the thing by CAE analysis. It is a graph which predicts the change of the hardness and the plastic strain of an outer-diameter part accompanying the change of a sizing allowance, taking a sizing allowance on a horizontal axis and taking hardness and the plastic strain of an outer-diameter part on a vertical axis | shaft.

  Embodiments of the present invention will be described with reference to the drawings. A steel tube made of bearing steel having an outer diameter 1 of φ72.4 mm and an inner diameter 2 of φ57.3 mm was cut into a width 3 of 29.7 mm to obtain a ring-shaped material 4 shown in FIG. Next, this ring-shaped material 4 is sized with an sizing margin of 0.8 mm and sized with an outer diameter of 71.6 mm. The outer diameter 1 is 71.6 mm, the width 3 is 29.9 mm, and the inner surface is turned. Thus, the material 5 before cold forging shown in FIG. 1B having an inner diameter 2 of φ56.6 mm was obtained. Further, the material 5 before cold forging is cold forged by die forging, the outer diameter 1 shown in (c) is φ72.3 mm, the inner diameter 2a of the shortest dimension which is the dimension of the central portion of the width 3 is φ56.8 mm, A cold forged blank 6 having an intermediate inner diameter 2b of φ32.3 mm and a width 3 of 32 mm at both ends of the width 3 was obtained.

  Dimension and accuracy between the ring-shaped material 4 before sizing the ring-shaped material 4 and the material 5 before sizing the outer diameter after obtaining the material 5 before cold forging in the above process The change of was measured. As a result, the standard deviation of the outer diameter dimension was improved from 0.023 before the outer diameter sizing to 0.012 after the outer diameter sizing. Further, the roundness of the outer diameter 1 of the ring-shaped material 4 having the number n of 36 was 0.07 mm on average before the outer diameter sizing, but the trueness of the material 5 before cold forging after the outer diameter sizing The circularity improved to 0.04 mm at maximum and 0.02 mm on average. Since the standard deviation was also 0.01, the cold forged product 6 was within a tolerance of the outer diameter of ± 0.1 mm. From these, it was found that an outer diameter sizing process can be introduced as an alternative to the turning process. That is, as shown in FIG. 2, by introducing an outer diameter sizing process in which the ring-shaped material 4 is inserted in the direction of the arrow into the inner diameter 7a of the slightly lower recess of the outer diameter sizing die 7, the outer diameter sizing process is performed. By sizing the outer diameter of the ring-shaped material 4 with the die 7, as shown in FIG. 3, the clearance 10 between the ring-shaped forging die 8 and the ring-shaped material 4 before cold forging is kept constant, The roundness of the outer diameter of the blank that is the ring-shaped material 4 can be improved.

  That is, FIG. 4 explains whether or not the roundness of the blank that is the ring-shaped material 4 needs to be improved by sizing the outer diameter. In FIG. 4A, the roundness of the blank of the ring-shaped material 4 is good, the outer diameter 1 of the ring-shaped material 4 is not displaced from the center 8a of the forging die 8, and therefore the forging die 8 Since the inner diameter is smaller than 2, there is no need for improvement. On the other hand, in (b), the roundness of the blank of the ring-shaped material 4 is poor, and the outer diameter 1 of the ring-shaped material 4 has a deviation from the center 8a of the forging die 8, and therefore the ring-shaped material 4 Since the portion of the outer diameter 1 of the portion indicated by the circle on the left side of 4 is larger than the inner diameter 2 of the forging die 8, the case where improvement is required is shown.

  By the way, as shown in FIG. 2, the ring-shaped material 4 before cold forging is subjected to sizing on the outer diameter, so that an increase in hardness due to work hardening may cause cracks. Therefore, the hardness distribution of the material surface of the material 5 before cold forging shown in FIG. 5A, which is the surface of the ring-shaped material 4 before sizing the outer diameter, and the outer diameter after sizing allowance of 0.8 mm. The hardness distribution of the material surface of the cold forging blank 6 of FIG. As can be seen in FIGS. 5A and 5B, the surface hardness of the cold forging blank 6 after sizing of the outer diameter was hardly changed from the hardness of the surface of the material 5 before cold forging. .

  Furthermore, in order to examine the versatility of the outer diameter sizing process, the outer diameter sizing was reproduced by CAE analysis. FIG. 6 shows the amount of change in dimensions between the ring-shaped material 4 before sizing the outer diameter and the material 5 before cold forging after the sizing allowance of 0.8 mm. According to FIG. 6, the outer diameter 1, the inner diameter 2, and the width 3 of the raw material 5 before cold forging after sizing allowance of 0.8 mm are both the values of the outer diameter sizing by the actual machine and the CAE obtained by the computer. Analysis values agreed well. Therefore, the influence of the sizing allowance on the hardness increase was estimated using CAE analysis. As shown in FIG. 7, even when the sizing allowance is 2.0 mm, the increase in hardness is predicted to be 7.5 Hv in terms of Vickers hardness. Thus, the increase in hardness due to the outer diameter sizing was slight compared to 50 Hv by shot blasting. By the way, although the hardness increase of the raw material before cold forging which has been shot blasted is about 50 Hv, since the crack is not generated in the outer diameter portion, the increase in hardness due to the outer diameter sizing of the means of the present invention is as described above. Thus, it is considered that cracks due to the increase in hardness did not occur in the outer diameter 1 because they were minor.

  As described above, since the present invention can create a bearing outer race shape material without turning the outer diameter, it is possible to improve the yield when making a cold forged product from a ring-shaped material, In this case, since no scratches are generated, no countermeasure is required, and batch processing is possible. Therefore, productivity can be improved and equipment costs can be reduced, and manufacturing costs can be reduced.

DESCRIPTION OF SYMBOLS 1 Outer diameter 2 Inner diameter 2a Shortest dimension inner diameter 2b Middle dimension inner diameter 3 Width 4 Ring-shaped material 5 Material before cold forging 6 Cold forging raw material 7 Outer diameter sizing die 7a Inner diameter 8 Forging die 8a Center 9 Punch 10 Clearance

Claims (2)

  In the method of processing the end face and the inner diameter of the ring-shaped material for cold forging simultaneously into the cold forging shape of the outer race by cold forging, the cold forging into the cold forging shape of the outer race is performed. A method for producing a ring-shaped material, characterized in that, prior to cold forging, after sizing the outer diameter of the ring-shaped material, the inner surface is turned to obtain a ring-shaped material for cold forging.   The ring-shaped material to be used for cold forging manufactured by the method according to claim 1 is further subjected to cold forging while maintaining a constant clearance between the forging die and the ring-shaped material before cold forging. To obtain a bearing shape material.

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