JP3765898B2 - Manufacturing method of bearing race - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
This invention relates to a method of manufacturing a bearing ring of miniature bearings.
[0002]
[Prior art]
Conventionally, the inner and outer rings of a miniature bearing have been manufactured by the following process.
First, the material is processed into a ring shape by cold forging, the ring-shaped material is turned to form and chamfer the raceway groove and seal groove, and then heat treated before grinding the raceway groove and inner and outer diameters. I do.
[0003]
[Problems to be solved by the invention]
However, the above manufacturing method has the following problems.
(1) In order to prevent the seal groove that was turned before heat treatment from being deformed by the heat treatment and to prevent scales and dust generated by the heat treatment from entering the seal groove, a vacuum furnace must be used for the heat treatment. In other words, the cost increases.
(2) Since chamfering cannot be performed only by cold forging, chamfering is performed by turning, and the cycle time increases accordingly.
(3) Since the ring-shaped material processed by cold forging has a large eccentricity, the machining allowance for grinding finish increases, and the cycle time increases accordingly.
{Circle around (4)} Since the ring-shaped shaped material processed by cold forging has a step difference in its inner diameter, the cycle time becomes longer to finish grinding the inner diameter.
[0004]
An object of the present invention is to provide a method for manufacturing a bearing race that can eliminate such a problem, reduce the manufacturing cost by omitting the turning process, and reduce the cycle time.
[0005]
[Means for Solving the Problems]
The method of manufacturing a bearing race of the present invention is a method of manufacturing a bearing race which is an outer ring or an inner ring of a miniature bearing, and is ring-formed by cold forging and sealed at both edges of the inner diameter surface or outer diameter surface. The method includes a step of obtaining a material having a stepped portion for mounting, a step of heat-treating the material, and a step of forming a raceway groove on an inner diameter surface or an outer diameter surface of the heat-treated material by grinding. .
According to this configuration, since it is possible to omit the conventionally required turning process, it is possible to reduce the cost and shorten the cycle time of the grinding finish.
[0006]
In the above structure, a seal mounting groove is formed by grinding the stepped portion of the inner surface or outer diameter surface of the heat-treated material. Further, the grinding of the raceway groove and the grinding of the seal mounting groove are simultaneously performed using a grindstone having a raceway grinding ridge on the outer periphery and a pair of seal mounting groove grinding ridges located on both sides of the ridge . In this configuration, there is no intrusion into seal mounting groove such scale and dust since machining the seal mounting groove after the heat treatment, there is no deformation of the seal mounting groove by heat treatment, the continuous regardless of the vacuum furnace heat treatment This can be done in a furnace, and the cost can be reduced accordingly.
Further, in the cold forging process, after the former process for forming the material in a ring shape, the inner and outer diameters of the material may be finished to a predetermined diameter by a pressing process. In the case of this configuration, the eccentricity generated in the material in the former process can be improved by the pressing process, and the step difference generated in the material in the former process can be eliminated by the pressing process. Therefore, the machining allowance in the grinding finish is reduced, and the cycle time can be shortened accordingly.
Moreover, in the said press process, you may make it chamfer the edge part of the internal-diameter surface or outer-diameter surface of a raw material. In the case of this configuration, since the chamfering can be performed in the cold forging process, the cycle time can be further shortened.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
An example of a proposal that is the basis of the present invention will be described with reference to FIG. The method of manufacturing a bearing race of this proposed example is a method of manufacturing an inner ring of a miniature deep groove ball bearing, which includes a process A for preparing a cold forged ring-shaped material 1H and a process for heat-treating the material 1H. B and process C in which the raceway groove 3 is formed by grinding on the outer diameter surface of the heat-treated material 1H.
[0008]
The cold forging process A includes a former process A1, a barrel process A2, and a pressing process A3. In the former process A1, for example, a material 1A (outer dimensions: 6.5 mm φ × 3.87 mm, weight: 1.006 gr) obtained by shearing a coil material or a bar material made of SUJ2, which is a high carbon chromium bearing steel, is formed into a ring shape by cold extrusion. The material 1E is processed by pressing the material 1A placed in the die with the corresponding punch (A11), the material 1B is inverted, and the same compression processing is repeated to obtain the disk-shaped material 1C and (A12). The material 1C is put into another die and pressed and compressed by a corresponding punch, and the material 1D is inverted and repeated to obtain a ring-shaped material 1E (A13, A14). The barrel process A2 is a process of deburring the material 1E processed in the former process A1.
[0009]
The pressing process A3 is a process of finishing the inner and outer diameters of the ring-shaped material 1E that has undergone the processing of the former process A1 to a predetermined diameter. In this process, the material width is finished and the chamfering 4 is performed on the edge of the inner diameter surface. Finishing is also done. In other words, the ring-shaped material 1E placed in the die is pressed with a corresponding punch and pressed to perform width finishing and chamfering on one side of the material 1E (A31), and the same pressing is performed by inverting the material 1F. Is repeated to finish the width and chamfering of the other side of the material 1F (A32), and then finish the inner and outer diameters (A33). In this pressing step A3, the outer diameter may be chamfered.
[0010]
Thus, by adding the pressing step A3 after the former step A1, the variation in the width of the material is reduced to 1/6, the variation in the outer diameter is 4/5, and the variation in the inner diameter is 1 /. Each can be improved to 6.
Further, the inner diameter chamfering process of the ring-shaped material 1H can be performed in the cold forging process A, and it is not necessary to add another process for the chamfering process. Therefore, the cycle time can be shortened accordingly.
Further, the eccentricity of the ring-shaped material 1H in the cold forging process A can be improved to 1/5 or less, and the step difference generated in the former process A1 can be eliminated by the pressing process A3. Therefore, it is possible to reduce the machining allowance for grinding finishing in the subsequent grinding process C, and to shorten the cycle time accordingly.
[0011]
In the process B of heat-treating the ring-shaped material 1H processed in the cold forging process A, for example, a continuous furnace is used. In the grinding process C in which the raceway groove 3 is formed by grinding on the outer diameter surface of the ring-shaped material 1H that has undergone heat treatment, a CBN electrodeposition grindstone is used. Thus, by using the CBN electrodeposition grindstone for grinding the raceway groove 3, the cycle time can be made comparable to the cycle time of the raceway groove processing in the conventional manufacturing method. In the grinding process C, the inner groove is ground in addition to the grinding of the raceway grooves 3, but as described above, the cold forging process A improves the eccentricity of the ring-shaped material 1H and removes the step difference. Therefore, it is possible to shorten the cycle time for grinding the inner diameter.
[0012]
As described above, in the above manufacturing method, the turning process can be omitted, the cycle time is shortened, and the machining accuracy is improved, so that the machining cost as a whole can be reduced.
[0013]
FIG. 2 shows an embodiment of the present invention. The bearing ring manufacturing method of this embodiment is a method of manufacturing an outer ring of a miniature deep groove ball bearing, and the fact that the cold forging process A includes a former process A1 and a pressing process A3 is shown in FIG. As in the case of the manufacturing method, a coil material of high carbon chromium bearing steel (SUJ2) is used as a material. In this case, in the cold forging process A, the step portion 5 for the seal mounting groove is formed at the opening edge of the inner diameter of the ring-shaped material 2H. Also in this embodiment, a continuous furnace is used in the process B of heat-treating the ring-shaped material 2H. In this case, since the seal mounting groove 6 is processed in the grinding process C after the heat treatment process B, the thermal deformation of the seal mounting groove processed before the heat treatment as in the case of the conventional example, the scale into the seal groove, and dust In order to prevent such intrusion, the use of a vacuum furnace is not necessary, thereby reducing the cost of the heat treatment process B.
[0014]
In the grinding process C, the raceway grooves 3 and the seal attachment grooves 6 are formed on the inner diameter surface of the ring-shaped material 1H by grinding. A CBN electrodeposition grindstone 7 shown in FIG. 3A is used for processing the raceway groove 3 and the seal mounting groove 6. The CBN electrodeposited grindstone 7 is intended the maximum outer diameter D _o which is slightly smaller than the minimum inside diameter D _i of the ring-shaped material 2H, raceway groove grinding ridges 7a and a pair of seal mounting groove on its outer peripheral surface Grinding ridges 7b, 7b. FIG. 3B is an enlarged cross-sectional view of the seal mounting groove grinding ridge 7b (S portion) of the CBN electrodeposition grindstone 7 of FIG. In this CBN electrodeposited grinding wheel 7, both seal mounting groove grinding ridges 7b are formed on the stepped portions 5 on both opening edges of the inner surface of the ring-shaped material 2H, and the raceway groove grinding ridges 7a are formed on the inner diameter of the ring-shaped material 2H. It arrange | positions so that it may each press to the intermediate part of a surface, and grinding of the track groove 3 and the seal attachment groove 6 is performed simultaneously. In the grinding process C, width grinding, outer diameter grinding, super processing, and tumbler processing are also performed.
[0016]
In the above-described embodiment, the method for manufacturing the outer ring having the seal mounting groove 6 has been described. However, depending on the type of the bearing, the inner ring manufacturing method has the same procedure as the method for manufacturing the outer ring on the outer diameter surface. The seal mounting groove may be ground. The material used in the present invention can be any steel as long as it can be used for rolling bearings (for example, SUS440C).
[0017]
【The invention's effect】
In the method for manufacturing a bearing race according to the present invention, it is possible to reduce the cost and shorten the cycle time by omitting the conventionally required turning process.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a method for manufacturing a bearing race according to a proposed example as the basis of the present invention.
FIG. 2 is an explanatory view showing a method for manufacturing a bearing race according to an embodiment of the present invention .
FIG. 3A is an explanatory view showing a use state of a grindstone employed in the manufacturing method, and FIG. 3B is an enlarged cross-sectional view showing a main part of the grindstone.
[Explanation of symbols]
1A to 1H ... Material 2A to 2H ... Material 3 ... Track groove 4 ... Chamfer 6 ... Seal mounting groove A ... Cold forging process A1 ... Former process A3 ... Pressing process B ... Heat treatment process C ... Grinding process

Claims (3)

A method of manufacturing a bearing race which becomes an outer ring or an inner ring of a miniature bearing, and is made of a ring-shaped material by cold forging and having a stepped portion for seal mounting on both edges of the inner surface or outer surface. a process of obtaining, the steps of heat treating the material, process and the in inner diameter surface or outer diameter surface of the heat-treated material step is formed by grinding the inner surface or the outer diameter surface to the raceway grooves of the heat-treated material Forming a seal mounting groove on the part by grinding, and grinding the track groove and seal mounting groove on the outer periphery, and a pair of seal mounting grooves positioned on both sides of the track groove grinding protrusion on the outer periphery. A method for manufacturing a bearing race which is simultaneously performed using a grindstone having grinding ridges . In the cold forging process, after the former step of forming the material into a ring shape, manufacturing method of the bearing ring of claim 1 Symbol placement finish inner and outer diameters of the material in the press process to a predetermined diameter. The method for manufacturing a bearing race according to claim 2 , wherein the pressing step chamfers the edge of the inner diameter surface or outer diameter surface of the material.

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