JP2014057999A - Method for manufacturing outer ring of rolling bearing unit for supporting wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an outer ring comprising an undercut section where an inner diameter is larger than that of both sides of a section in an axial direction, at an intermediate section in the axial direction at a low cost.SOLUTION: Firstly, by executing plastic working of metallic material 10 in processes of (A) → (B) → (C) → (D) → (E), intermediate material 19, without comprising a small diameter section or an undercut section and comprising sections for serving as the small diameter section and the undercut section and formed as cylindrical parts, is formed. Thereafter, a diameter of a part of the cylindrical parts 18 is reduced by the plastic working in processes (E) → (F) → (G), and final intermediate material 9 comprising the small diameter section and the undercut section is formed.

Description

  The present invention relates to a method of manufacturing an outer ring equivalent member constituting a wheel bearing rolling bearing for rotatably supporting a wheel with respect to a suspension device of an automobile. In particular, the present invention intends to realize a manufacturing method that can produce an outer ring equivalent member having a so-called undercut portion, which has an inner diameter larger than both sides of the portion in the axial direction in the axial direction, at low cost. Yes.

  A wheel-supporting rolling bearing for rotatably supporting a wheel with respect to an automobile suspension system is composed of a double-row outer ring raceway formed on an inner peripheral surface of an outer ring equivalent member and a multi-row outer ring raceway formed on an outer peripheral surface of an inner ring equivalent member. By providing a plurality of rolling elements for each row between the inner ring raceways of the rows, relative rotation between the outer ring equivalent member and the inner ring equivalent member is made free. Which of the outer ring equivalent member and the inner ring equivalent member is coupled and fixed to the suspension device and to which the wheel is supported and fixed (which is a stationary wheel and which is a rotating wheel) depends on the design. There is also a structure. The pitch circle diameters of the rolling elements in both rows are often the same as each other, but different structures are also known. In addition, both structures are known depending on the difference in whether the pitch circle diameter in which row is to be increased or the wheel to be supported is a driven wheel or a driving wheel in different cases.

  As described above, there are many specifications for the rolling bearing unit for supporting the wheel, and the necessity for realizing a shape different from the conventional one is increasing due to diversification of requirements in recent years. For example, among the double row outer ring raceways formed on the inner peripheral surface of the outer ring, a shape in which the inner diameter of the outer ring raceway portion near the center with respect to the axial direction is sufficiently larger than the inner diameter of both side portions in the axial direction of the outer ring raceway, That is, there is a case where it is required to provide an outer ring having an undercut portion at an axially intermediate portion of the inner peripheral surface. In any case, the outer ring is made of a metal material such as medium carbon steel, but if an outer ring having an undercut portion as described above on the inner peripheral surface is made by a conventional method, the cost increases. It is difficult to ensure sufficient durability. This point will be described with reference to FIG.

  The shape of the outer ring 1 to be manufactured is indicated by a chain line in FIGS. This outer ring 1 has a main body portion formed in a substantially cylindrical shape, and double row angular outer ring raceways 2a and 2b are arranged at two positions apart from each other in the axial direction on the inner peripheral surface. Each has a flange portion 3 in the middle of the direction. Both the outer ring raceways 2a and 2b are formed on both axial side surfaces of the first small-diameter portion 4 having a smaller inner diameter, provided in the axially intermediate portion of the inner peripheral surface of the outer ring 1. The shape described above is the same as that of the outer ring of a wheel bearing rolling bearing unit that has been generally used in the past, and can be produced without any particular problems by the conventional manufacturing method. In particular, in the case of the outer ring 1 shown in FIG. 10, the diameter of one end portion in the axial direction (upper end portion in FIG. 10) of the cylindrical main body portion 5 is made smaller than the diameter of the intermediate portion in the axial direction or the other end portion. Thus, this portion is the second small diameter portion 6. As the second small diameter portion 6 is provided, the portion between the second small diameter portion 6 and the first small diameter portion 4 has an inner diameter larger than those of the first and second small diameter portions 4 and 6. A large undercut portion 7 is obtained. Based on the presence of such an undercut portion 7, it is difficult to reduce the manufacturing cost of the outer ring 1 and to ensure durability.

  That is, in general, the outer ring 1 is manufactured by performing a forging process, which is a kind of plastic working, on a cylindrical material made of medium carbon steel and making it an intermediate material close to the shape of the outer ring after completion. The intermediate material is subjected to a cutting process such as cutting and grinding to obtain the outer ring 1 having a desired shape and surface properties. The forging process is performed by crushing (plastically deforming) the material in the axial direction between a receiving die that moves in the axial direction of the material and a pressing die. When the intermediate material has a shape portion close to the undercut portion 7 (a portion recessed radially outward from the inner peripheral surface as compared to the portion between the end openings), after the forging process as described above Of the receiving mold and the pressing mold, the mold obtained by processing the portion cannot be separated from the intermediate material. For this reason, when the outer ring 1 as shown by a chain line in FIG. 10 is manufactured by a conventional method, an intermediate material 8 having no undercut portion as shown in FIG. 8, it is necessary to largely scrape the inner peripheral surface intermediate portion corresponding to the undercut portion 7. For this reason, the labor of processing increases, the yield of materials deteriorates and the manufacturing cost increases, and it becomes difficult to improve the surface properties of both the outer ring raceways 2a and 2b. That is, as the intermediate portion of the inner peripheral surface is greatly scraped, so-called fiber flow cut portions in the metal material are easily exposed on the surfaces of the outer ring raceways 2a and 2b. In addition, among the metal materials constituting the material, a clean portion (a radial intermediate portion of the material) that is advantageous in terms of ensuring the durability of both the outer ring raceways 2a and 2b is designated as the outer ring raceways 2a and 2b. It becomes difficult to expose the part.

  It corresponds to the undercut portion 7 of the outer ring 1 after completion, as shown in FIG. 10B, with respect to the conventional manufacturing method as shown in FIG. If the intermediate material 8a having a larger inner diameter can be produced by plastic working such as forging, all of the above problems can be solved. However, as described above, such an intermediate material 8a cannot be manufactured by a conventional manufacturing method.

  Conventionally, methods described in Patent Documents 1 and 2 are known as a method of manufacturing a metal part having an undercut portion by plastic working such as forging. Among these, in the manufacturing method described in Patent Document 1, a cylindrical portion protruding in the axial direction from the radially intermediate portion of the annular portion is bent inward in the radial direction, whereby a portion closer to the inner diameter of the annular portion. The undercut portion is defined between the cylindrical portion and the tip portion of the cylindrical portion. Moreover, in the manufacturing method described in Patent Document 2, an axial intermediate portion or other end portion of an intermediate material having a large diameter portion at one axial end portion and a cylindrical intermediate portion or other end portion in the axial direction is used. It crushes to an axial direction, forms another large diameter part, and makes an undercut part between this another large diameter part and the said large diameter part.

  In the manufacturing method described in Patent Document 1, since the shape of the portion where the undercut portion is provided is limited (limited to the inner diameter side portion of the partial conical cylindrical shape), the race ring member of the wheel bearing rolling bearing unit Not suitable for manufacturing. In addition, the manufacturing method described in Patent Document 2 considers that a metal part having an undercut portion existing on the outer peripheral surface is taken into consideration, and the inner peripheral surface such as the outer ring 1 shown in FIG. This is not suitable for the production of the race member of the wheel bearing rolling bearing unit having the undercut portion 7.

JP 2007-125614 A JP 2008-194704 A International Publication No. 2009/096434 Pamphlet

  In view of the circumstances as described above, the present invention can manufacture an outer ring-equivalent member having an undercut portion at an intermediate portion in the axial direction having an inner cut larger than both sides of the portion in the axial direction at low cost. Invented to realize the method.

The bearing member of the rolling bearing unit for supporting a wheel, which is the object of the manufacturing method of the present invention, is made of a metal material in a substantially cylindrical shape, and has an inner diameter smaller than the axially opposite side portions at the axially intermediate portion of the inner peripheral surface. The first small diameter portion is provided with a second small diameter portion at a portion spaced apart from the first small diameter portion in the axial direction, and a portion between the first and second small diameter portions is provided between the first and second small diameter portions. The undercut portion has a larger inner diameter than both small diameter portions.
In particular, any of the manufacturing methods of the bearing member of the rolling bearing unit for wheel support of the present invention does not have the second small diameter portion and the undercut portion by first plastically processing a metal material. An intermediate material having a cylindrical portion as the second small diameter portion and the undercut portion is formed. Thereafter, the inner diameter of the cylindrical portion is reduced by plastic working such as drawing or fleshing, so that the second small diameter portion and the undercut portion are formed (technical commonality of each invention).

After forming the intermediate material in this way, in order to form the second small diameter portion and the undercut portion, in the case of the invention according to claim 1, the diameter of a part of the cylindrical portion is plastically processed. Shrink by (drawing). The portion whose diameter is reduced is also cylindrical, and this portion is parallel to the central axis.
In order to carry out the invention described in claim 1, specifically, as in the invention described in claim 2, first, by crushing a metal and cylindrical material from both sides in the axial direction, A preliminary intermediate material having a pair of circular concave holes opened on both end faces and a partition wall partitioning the circular concave holes is formed. Thereafter, a central portion of the partition wall is punched out to form a circular hole, and a portion near the outer diameter of the partition wall remaining around the circular hole is defined as a first small diameter portion.
Further, when the invention described in claim 2 is carried out, preferably, as in the invention described in claim 3, the central portion of the partition wall is punched to form a circular hole (the same process). The inner diameter of the portion close to the opening of one of the circular concave holes is reduced, and the second small diameter portion and the undercut portion are included. Form.

Alternatively, after forming the intermediate material as described above, in order to form the second small diameter portion and the undercut portion, as in the invention described in claim 4, it is larger than the inner diameter of the cylindrical portion. By pushing a punch having an outer diameter smaller than the outer diameter into the cylindrical portion from the axial end surface of the cylindrical portion, a part of the metal material constituting the cylindrical portion is placed on the inner diameter side of the cylindrical portion and in the axial direction. The second small-diameter portion and the undercut portion are formed by moving the portion closer to the center (subjecting to the meat).
In order to carry out the invention described in claim 4, specifically, as in the invention described in claim 5, one end face is obtained by crushing a metal columnar material in the axial direction. A first preliminary intermediate material having a circular concave hole whose inner diameter is smaller than that of the middle part or the one end part and a bottom plate part that closes the bottom part of the circular concave hole is formed. Thereafter, the bottom plate portion is punched out to provide an intermediate material having a cylindrical portion penetrating in the axial direction and having the other axial end portion of the cylindrical portion as a first small diameter portion. Next, the punch is pushed in from the axial end surface of the cylindrical portion of the intermediate material.
Further, when carrying out the invention described in claim 5, preferably, as in the invention described in claim 6, first, the axial end surface is changed from the axial end surface of the cylindrical portion of the intermediate material. The amount of protrusion in the axial direction of the portion to be pressed is pushed in the preforming punch that is large at the radially intermediate portion and also small at the radially inner end portion. Then, the metal material near the one end of the cylindrical portion is moved to the central portion in the axial direction to form a spare second small diameter portion having a shape in which the portion near the inner diameter protrudes toward one end in the axial direction. After that, the finish forming punch is pushed in such that the protruding amount in the axial direction of the portion that presses the spare second small diameter portion is large at the inner diameter portion and gradually decreases at the outer diameter portion. Then, the metal material in the portion closer to the inner diameter of the reserve second small diameter portion is moved to the central portion in the axial direction to form the second small diameter portion.

  According to the method of manufacturing the bearing member of the rolling bearing unit for supporting a wheel according to the present invention configured as described above, the undercut has a larger inner diameter than the both sides of the portion in the axial direction at the intermediate portion in the axial direction. An outer ring equivalent member having a portion can be produced at low cost. That is, by subjecting a metal material such as medium carbon steel to plastic processing such as forging, it can be processed into an intermediate material having a shape close to the completed state including the undercut portion. For this reason, it is not necessary to greatly cut off the intermediate portion of the inner peripheral surface of the intermediate material, and the manufacturing cost can be reduced by reducing the labor of processing and improving the yield of the material. In addition, since it is not necessary to greatly scrape the inner peripheral surface intermediate portion of the intermediate material, the fiber flow cutting portion is exposed on the surface portion of the double row outer ring raceway provided on the inner peripheral surface of the outer ring equivalent member, Or it becomes easy to prevent that the non-clean part in the said material exposes to these both outer ring track parts.

Sectional drawing which shows the 1st example of embodiment of this invention in process order. Sectional drawing which shows the preliminary process for shrinking | reducing the diameter of the one end part of an intermediate material with the state (A) just before a process start, and the state (B) just after completion | finish of a process. Sectional drawing which similarly shows finish processing with the state (A) just before a process start, and the state (B) just after completion | finish of a process. Sectional drawing similar to FIG. 2 which shows the 2nd example of embodiment of this invention. Sectional drawing which shows the 3rd example in order of a process. Sectional drawing which shows the preliminary process for moving the metal material of the one end part inner diameter part of an intermediate material to the axial direction intermediate part in the state (A) just before a process start, and the state (B) just after completion | finish of a process. The X section expanded sectional view of (B) of Drawing 6 for explaining the movement state of the metal material accompanying this preliminary processing. Sectional drawing which shows the finishing process for moving the metal material of the one end part inner diameter part of an intermediate material to the axial direction intermediate part in the state (A) just before a process start, and the state (B) just after completion | finish of a process. The Y section expanded sectional view of FIG. 8 (B) for demonstrating the movement state of the metal material accompanying this finishing process. The partial cross section which shows each when the outer ring used as the object of the manufacturing method of this invention is made with the conventional manufacturing method (A), and when it is made with the manufacturing method of this invention (B).

[First example of embodiment]
1 to 3 illustrate a first example of an embodiment of the present invention corresponding to claims 1 and 2. In the manufacturing method of this example, as shown in FIG. 1G, the final intermediate material 9 having a larger inner diameter corresponding to the undercut portion 7 (see FIG. 10) of the finished outer ring 1 is plasticized. It is made by forging which is a kind of processing. The shape of the final intermediate material 9 is basically the same as that of the intermediate material 8a shown in FIG. The forging process described below, which sequentially plastically deforms the material 10 to form the final intermediate material 9, is performed by heating (heating the material to be processed or the intermediate material at each stage to a temperature exceeding 900 ° C. It is preferable that the processing force (capacity of the press machine) is reduced and the work piece is less susceptible to damage such as cracks. However, depending on the shape and dimensions of the workpiece, it can be performed warmly (in a state where the workpiece is heated to 600 to 900 ° C.). Furthermore, the initial stage processing with relatively little change in the shape of the workpiece can be performed cold depending on the dimensions of the workpiece.

  In the case of the manufacturing method of the present example in order to produce the final intermediate material 9 as described above, first, a long material is cut into a predetermined length to obtain a cylindrical shape as shown in FIG. Material 10 is obtained. Next, by crushing the material 10 in the axial direction to reduce the axial dimension and to increase the outer diameter, the outer diameter of the central portion in the axial direction as shown in FIG. The thickest disc-shaped first intermediate material 11 is the largest.

Next, the first intermediate material 11 is subjected to a first-stage rough forming process to obtain a second intermediate material 12 as shown in FIG. The rough finishing process is performed by forging process in which the first intermediate material 11 is crushed between a pressing mold and a receiving mold that move in the axial direction.
The second intermediate material 12 thus produced is then subjected to a second stage of rough forming to obtain a third intermediate material 13 as shown in FIG. The third intermediate material 13 includes a raw flange portion 15 on the outer peripheral surface of the cylindrical portion 14 and a partition wall portion 16 on the inner diameter side portion. Of the cylindrical portion 14, with respect to the one-side cylindrical portion 17 existing on one side (lower side in FIG. 1) with respect to the axial direction from the bare flange portion 15, the diameter and thickness dimension in the radial direction are set to the final intermediate material 9. The diameter and the thickness dimension of the corresponding part are the same. On the other hand, with respect to the other cylindrical portion 18 existing on the other side (upper side in FIG. 1) in the axial direction than the raw flange portion 15 in the cylindrical portion 14, the diameter of the final intermediate material 9 is the same. Is larger than the diameter of the corresponding part, and the thickness dimension in the radial direction is smaller than the thickness dimension of the corresponding part. In addition, the inner diameter side part of the said cylindrical parts 17 and 18 is equivalent to the circular recessed hole part described in the claim.
Such a third intermediate material 13 is subjected to a piercing (punching by pressing) process for punching and removing the central portion excluding the outer diameter side end portion of the partition wall portion 16, as shown in FIG. Such a fourth intermediate material 19 is used. The circular center hole 35 formed by the piercing process corresponds to the first small diameter portion described in the claims.

  None of the first to fourth intermediate materials 11 to 13 and 19 produced by the above processing has an undercut portion that obstructs the retraction of the mold (between the first small diameter portion and the openings at both ends). In addition, there is no portion having an inner diameter smaller than that of the first small diameter portion). Therefore, for example, it can be easily processed by a well-known forging method described in Patent Document 3 and the like. For this reason, illustration and description of the specific structure and operation of a mold or the like used in the processing method from the material 10 to the fourth intermediate material 19 are omitted.

  The fourth intermediate material 19 is subjected to diameter reduction processing by forging, which is a feature of the present invention, on the other side cylindrical portion 18, through the fifth intermediate material 20 shown in FIG. The final intermediate material 9 shown in FIG. Hereinafter, the process of using the fourth intermediate material 19 as the fifth intermediate material 20 and further using the fifth intermediate material 20 as the final intermediate material 9 will be described in detail with reference to FIGS.

  First, in order to process the fourth intermediate material 19 into the fifth intermediate material 20, as shown in FIG. 2A, the fourth intermediate material 19 is secured to a base of a press machine. Set on the molding die 21. The preforming die 21 has a circular hole portion 22 into which the one-side cylindrical portion 17 of the fourth intermediate material 19 is fitted with no gap at the center, and a step portion 23 for abutting the end surface of the one-side cylindrical portion 17. And a recessed hole portion 24 for accommodating the raw flange portion 15 on the outer peripheral surface of the fourth intermediate material 19. When the fourth intermediate material 19 is set in such a preforming die 21, the preforming punch unit 25 provided above the preforming die 21 is moved down to the other cylindrical portion 18. At the same time, the thickness of the other cylindrical portion 18 in the radial direction is increased.

  The preforming punch unit 25 is formed by fixing a preforming inner punch 26 and a preforming outer punch 27 concentrically with each other to the lower surface of the ram of the press machine. Of these, the outer diameter of the preforming inner punch 26 is smaller than the inner diameter of the other cylindrical portion 18 to be reduced, and the fifth intermediate material 20 is obtained by reducing the diameter of the other cylindrical portion 18. The size is commensurate with the inner diameter of the other cylindrical portion 18a (slightly smaller than the inner diameter when springback is considered, or the same as the inner diameter when not necessary). The preforming outer punch 27 has an annular shape as a whole, and has a stepped center hole 28 having a circular cross section. The central hole 28 is formed by connecting a lower end portion of the small diameter portion 29 provided at the upper end portion and an upper end portion of the large diameter portion 30 provided at the intermediate portion by the step portion 31, and further, opening the lower end of the large diameter portion 30. The part is provided with a guide inclined surface 32 that is inclined in a direction in which the inner diameter increases as it goes downward. Of these, the inner diameter of the large-diameter portion 30 is commensurate with the outer diameter of the other cylindrical portion 18a of the fifth intermediate material 20 (in consideration of springback, it is slightly smaller than this outer diameter, and should be taken into consideration). If not, it is the same as this outer diameter). Further, the inner diameter of the lower end portion of the guide inclined surface 32 is larger than the outer diameter of the end surface of the other cylindrical portion 18 to be reduced in diameter.

  In order to manufacture the fifth intermediate material 20, as described above, the fourth intermediate material 19 is set on the preforming die 21 as shown in FIG. The preforming punch unit 25 is lowered with a large force together with the ram of the press machine. Then, the said other side cylindrical part 18 approachs into the said large diameter part 30, being guided by the said guide inclined surface 32, and reducing the diameter, The said 5th intermediate material 20 provided with the said other side cylindrical part 18a. To be processed. The thickness dimension in the radial direction of the other cylindrical portion 18a of the fifth intermediate material 20 is thicker than the thickness dimension in the same direction of the other cylindrical portion 18 of the fourth intermediate material 19 by the reduced diameter. Become. Thus, in the case of this example, the thickness of the other cylindrical portion 18 having a thickness smaller than the thickness (predetermined value) of the other cylindrical portion 18a to be manufactured is reduced and the thickness is increased. Therefore, it is easy to reduce the diameter of the other cylindrical portion 18. 1 (E) → (F) in FIG. 1 and (A) → (B) in FIG. 2, the end face of the other cylindrical portion 18a is The stepped portion 31 of the central hole 28 of the pre-shaped outer punch 27 remains separated. The reason for this is to prevent the thickness of the other cylindrical portion 18a from becoming excessively large so that the following finish forming operation for reducing the diameter can be easily performed.

  As described above, if the fourth intermediate material 19 is pressed between the preforming die 21 and the pre-shaping punch unit 25 to obtain the fifth intermediate material 20, then the fifth intermediate material 20 is obtained. As shown in FIG. 3, the fifth intermediate material 20 is pressed between the finish molding die 33 and the finish molding punch unit 34 to obtain the final intermediate material 9. The basic structures of the finish molding die 33 and the finish molding punch unit 34 are the same as those of the preforming die 21 and the preforming punch unit 25. However, the finish forming die 33 is fitted in the center hole 35 of the fourth intermediate material 19 to the fifth intermediate material 20 (a circular hole formed by punching the partition wall portion 16) without a gap. The mandrel 36 is provided. In a state where the fifth intermediate material 20 is set on the finish molding die 33, the tip portion (lower half) of the one-side cylindrical portion 17 of the fifth intermediate material 20 is a cylinder provided on the finish molding die 33. It is accommodated in a space (cavity) defined by the inner peripheral surface of the portion 22a, the upper surface of the stepped portion 23a, and the outer peripheral surface of the base end portion of the mandrel 36. Further, the front half (upper half) of the mandrel 36 is fitted into the center hole 35 without a gap.

  When the finish molding punch unit 34 is lowered from this state, the other cylindrical portion 18a is guided by the guide inclined surface 32a and enters the large diameter portion 30a while reducing its diameter, and this other cylindrical portion is introduced. The final intermediate material 9 including the other cylindrical portion 18b having a smaller diameter and a larger thickness than the portion 18a is processed. The other cylindrical portion 18b corresponds to the second small diameter portion described in the claims. In this way, in the finish molding using the fifth intermediate material 20 as the final intermediate material 9, unlike the above-described preliminary molding, the end surface of the other cylindrical portion 18b is used as the inner punch for finish molding. 37 and the step forming portion 31 a provided on the finish forming outer punch 38 constituting the finish forming punch unit 34. The other cylindrical portion 18b is pressed in the axial direction with a sufficiently large force while the inner and outer peripheral surfaces are constrained, and the shape and size of the other cylindrical portion 18b are changed to the finish forming punch. Finish with good precision according to the shape of the inner surface of the unit 34 (obtain a clear undercut shape). During finish molding performed in this manner, a large force (load, stress) is applied to the fifth intermediate material 20 to the final intermediate material 9. However, since the mandrel 36 is fitted in the center hole 35 of the fifth intermediate material 20 to the final intermediate material 9 and the inner diameter side of the one-side cylindrical portion 17 without any gap, the fifth intermediate material 20 to the final intermediate material 9 are inserted. No harmful deformation occurs in the intermediate material 9 other than the other axial side portions 18a to 18b.

The final intermediate material 9 obtained in this step is a material before cutting (turning) and grinding described later, and its shape is not the final shape as a product. Accordingly, since particularly high shape accuracy and dimensional accuracy are not required, it is not always necessary to abut the end surface of the other cylindrical portion 18b against the step portion 31a.
In the above embodiment, the fourth intermediate material 19 shown in FIG. 1E is processed into the final intermediate material 9 shown in FIG. The case where the fifth intermediate material 20 is molded has been described. However, this step can be changed depending on the degree of processing the other cylindrical portion 18 of the fourth intermediate material 19 into the other cylindrical portion 18b of the final intermediate material 9 (a large amount of processing). For example, when the amount of processing is small (the ratio of diameter reduction is low), the processing step of the fifth intermediate material 20 may be omitted, and the fourth intermediate material 19 may be processed directly into the final intermediate material 9. it can. Conversely, when the amount of processing is large (the ratio of diameter reduction is high), the processing from the fourth intermediate material 19 to the final intermediate material 9 can be performed in more stages.

  In any case, the final intermediate material 9 obtained is taken out between the finish molding die 33 and the finish molding punch unit 34 and sent to the next finishing process (cutting process and grinding process), The outer ring 1 is completed (see the chain line in FIG. 10). The final intermediate material 9 produced by the manufacturing method of this example has a slightly larger cross-sectional shape than the cross-sectional shape of the outer ring 1 also indicated by a chain line, as shown by the solid line in FIG. . For this reason, the machining allowance in the finishing process is small, and the outer ring 1 having an undercut portion as shown by a chain line in FIG. 10 is obtained by improving the efficiency of the finishing process and improving the yield of the material. Can be manufactured at low cost. Further, it is difficult to expose the cut portion of the fiber flow on the surface of the pair of outer ring raceways, which is advantageous in terms of ensuring the rolling fatigue life of both outer raceways.

[Second Example of Embodiment]
FIG. 4 shows a second example of an embodiment of the present invention corresponding to claims 1 to 3. In the case of this example, the step of processing the fourth intermediate material 19 shown in FIG. 1E is omitted, and the third intermediate material 13 shown in FIG. It is intended to be processed into the shape of the fifth intermediate material 20 shown in FIG. Therefore, in the case of this example, the axial length of the preforming inner punch 26a constituting the preforming punch unit 25a is set to the preforming inner punch 26 used in the first example of the embodiment described above. It is longer than (see FIG. 2) and the outer peripheral edge of the tip is sharpened. Then, as shown in FIG. 4 (A) → (B), the central portion of the partition wall portion 16 existing in the inner diameter side axial direction intermediate portion of the third intermediate material 13 is punched to form a circular center hole 35. At the same time (actually slightly before and after in time), the diameter of the other cylindrical portion 18 is reduced and the thickness dimension of the other cylindrical portion 18 in the radial direction is increased. Then, it is processed into the shape of the fifth intermediate material 20 shown in FIG. Such a processing method of this example can be carried out when the inner diameter of the center hole 35 is smaller than the inner diameter of the other cylindrical portion 18a after processing (this condition is satisfied in most cases).
Other configurations, operations, and effects are the same as those of the first example of the above-described embodiment, and thus overlapping illustrations and descriptions are omitted.

[Third example of embodiment]
FIGS. 5-9 has shown the 3rd example of embodiment of this invention corresponding to Claims 4-6. In the manufacturing method of this example, as shown in FIG. 5G, the final intermediate material 9a in which the inner diameter of the portion corresponding to the undercut portion 7 (see FIG. 10) of the outer ring 1 after completion is increased is plasticized. It is made by forging which is a kind of processing. The shape of the final intermediate material 9a is basically the same as the intermediate material 8a shown in FIG. 10B and the final intermediate material 9 shown in FIG. However, in FIG. 5 and FIGS. 10 and 1, the axial positions are upside down. Note that the forging process described below, which sequentially plastically deforms the material 10 to obtain the final intermediate material 9a, can be performed hot to reduce the processing force (capacity of the press machine) and to be processed. Although it is preferable from the viewpoint of making it difficult to cause damage such as cracks in the object, it can be performed warmly depending on the shape and dimensions of the workpiece. Furthermore, the initial stage processing with relatively little change in the shape of the workpiece can be performed cold depending on the dimensions of the workpiece.

  In the case of the manufacturing method of the present example in order to produce the final intermediate material 9a as described above, first, a long material is cut into a predetermined length to obtain a cylindrical shape as shown in FIG. Material 10 is obtained. Next, the material 10 is crushed in the axial direction to reduce the axial dimension and perform an upsetting process to expand the outer diameter, so that the outer diameter of the central portion in the axial direction as shown in FIG. The largest intermediate material 11a in the form of a beer barrel is used.

Next, the first intermediate material 11a is subjected to a first-stage rough forming process to obtain a second intermediate material 12a as shown in FIG. The rough finishing process is performed by forging process in which the first intermediate material 11a is crushed between a pressing mold and a receiving mold that move in the axial direction.
The second intermediate material 12a thus produced is then subjected to a second stage rough forming process to obtain a third intermediate material 13a as shown in FIG. The third intermediate material 13a has a bare flange portion 15a on the outer peripheral surface of the cylindrical portion 14a, and a bottom plate portion 39 on one end portion (the lower end portion in FIG. 5D) of the cylindrical portion 14a. Further, a portion closer to one end of the cylindrical portion 14a (portion closer to the bottom plate portion 39 than the raw flange portion 15a) is a middle portion or a portion closer to the other end (the portion opposite to the bottom plate portion 39 with respect to the raw flange portion 15a). ) And a thin wall. The portion of the third intermediate material 13a surrounded by the first preliminary intermediate material described in the claims by the inner peripheral surface of the cylindrical portion 14a and the inner surface of the bottom plate portion 39 is described in the claims. It corresponds to each circular concave hole.

Such third intermediate material 13a is subjected to piercing (punching by pressing) processing for punching and removing the entire bottom plate portion 39 to form a fourth intermediate material 19a as shown in FIG. 5E. . The fourth intermediate material 19a is formed in the intermediate material described in the claims with a small-diameter and thin-walled one-side cylindrical portion 40 as compared to the intermediate portion or the portion near the other end. It corresponds to the first small diameter portion described in the claims. In the case of this example, the diameter and the thickness dimension of the one-side cylindrical portion 40 are the same as the diameter and thickness dimension of the corresponding portion of the final intermediate material 9a. On the other hand, with respect to the raw flange portion 15a in the cylindrical portion 14a, the thickness of the corresponding portion of the final intermediate material 9a with respect to the other cylindrical portion 41 existing on the opposite side of the bottom plate portion 39. It is larger than the size. Further, the outer diameter of the other cylindrical portion 41 is the same as the outer diameter of the corresponding portion of the final intermediate material 9a.
None of the first to fourth intermediate materials 11a to 13a, 19a produced by the above processing has an undercut portion that becomes an obstacle to retracting the mold. Therefore, it can be easily processed by a conventionally known forging method. For this reason, illustration and description are omitted for the specific structure and operation of the mold or the like used in the processing method from the material 10 to the fourth intermediate material 19a.

  The fourth intermediate material 19a is subjected to meat gathering processing, which is a feature of the present invention, on the other side cylindrical portion 41, through the fifth intermediate material 20a shown in FIG. The final intermediate material 9a is used. The processing using the fourth intermediate material 19a as the fifth intermediate material 20a and the processing using the fifth intermediate material 20a as the final intermediate material 9a are both performed with a die having a punch (pressing die) and a mandrel. (Receiving mold) This is performed by a meat gathering process in which a part of the intermediate material is pressed in the axial direction. First, an undercut portion forming operation using the fourth intermediate material 19a as the fifth intermediate material 20a will be described with reference to FIGS.

  First, as shown in FIG. 6A, the fourth intermediate material 19 a is set on a fixed die 43 provided with a mandrel 42 at the center, and further suppressed by a movable die 44. That is, the one-side cylindrical portion 40 is interposed in a cylindrical space between the outer peripheral surface of the mandrel 42 and the recess 45 formed in the fixed die 43 so as to allow deformation of the one-side cylindrical portion 40. Without insertion (substantially without a gap). The raw flange portion 15 a is accommodated in a recessed hole portion 24 a formed on the upper surface of the fixed die 43. Further, an annular movable die 44 called a floating die is provided in the other cylindrical portion 41 without interposing a gap that allows the outer diameter of the other cylindrical portion 41 to expand (substantially a gap). (Without intervening).

  From this state, as shown in FIGS. 6A to 6B, the preforming punch 46 is pressed against the tip surface of the other cylindrical portion 41. Then, the metal material near the tip of the other cylindrical portion 41 (upward in FIGS. 5 to 6) and at the inner diameter side half is moved toward the axial center of the fourth intermediate material 19a, and the fifth intermediate material is moved. 20a. Of the preforming punch 46, the outer diameter of the preforming pressing portion 47 that presses the tip surface of the other cylindrical portion 41 is larger than the inner diameter of the other cylindrical portion 41 and is also smaller than the outer diameter. That is, the preforming punch 46 is, in order from the front end side (lower end side), a cored bar portion 48 having a small outer diameter near the inner diameter of the other cylindrical portion 41, the preforming pressing portion 47, The outer cylindrical portion 41 has an outer diameter that is larger than the inner diameter and smaller than the outer diameter, and has a tapered outer peripheral surface that is inclined in a direction in which the outer diameter gradually increases toward the base end (upper end). An intermediate step portion 49 and an upper large-diameter portion 50 that can be inserted without rattling on the inner diameter side of the movable die 44 are provided. The preforming pressing portion 47 is provided as a front end surface of the intermediate step portion 49, which is a continuous portion with the intermediate step portion 49 and the core metal portion 48. The preforming pressing portion 47 has a partial arc-shaped cross-sectional shape, and the protruding amount in the axial direction is large at the radially intermediate portion, and is also small at the inner diameter portion and the outer diameter portion.

  As the preforming punch 46 is pushed in, the metal material of the portion (a) in FIG. 7 (the upper portion of the two locations with fine hatching in FIG. 7) is pressed downward, The metal material bulges to the lower part (similarly, the lower part of the fine hatching) of the figure. That is, the metal material of the radially inner portion near the opening end (one end, upper end) of the other cylindrical portion 41 is moved radially inward at the axially central portion. Then, as shown in FIG. 5F and FIG. 6B, a preliminary small-diameter portion 51 having a shape in which a portion closer to the inner diameter protrudes toward one end side (upper side) in the axial direction (described in the claims) The fifth intermediate material 20a is provided with a preliminary second small diameter portion). During the preforming process, the upper large-diameter portion 50 enters the inner diameter side of the movable die 44 without rattling and ensures concentricity between the fourth intermediate material 19a and the preforming punch 46. Further, the cored bar part 48 regulates the inner diameter dimension of the preliminary small diameter part 51 to prevent the preliminary small diameter part 51 from becoming excessively small, thereby obtaining the preliminary small diameter part 51 having a desired dimension. .

  As shown in FIG. 8, the fifth intermediate material 20 a is subjected to finish molding so that the preliminary small diameter portion 51 becomes the small diameter portion 52 (second small diameter portion described in claims). The final intermediate material 9a as shown in (G) of FIG. 8 and (B) of FIG. In this finish forming process, as shown in FIG. 8A, the fifth intermediate material 20a is set on a fixed die 43a provided with a mandrel 42a at the center, and further suppressed by a movable die 44a. The shapes, dimensions, and functions of the mandrel 42a, the fixed die 43a, and the movable die 44a are the same as the mandrel 42, the fixed die 43, and the movable die 44 (see FIG. 6) used for the above-described preforming.

  From the state in which the fifth intermediate material 20a is set to the mandrel 42a, the fixed die 43a, and the movable die 44a, the finish forming punch 53 is provided as shown in FIGS. The finishing molding pressing portion 54 is pressed against one side surface (upper surface) in the axial direction of the preliminary small diameter portion 51. And among the metal materials which comprise the preliminary | backup small diameter part 51, the metal material which comprises an inner diameter side half part is moved from the axial direction one end side to the center side (from the upper side of FIGS. 8-9 to the lower side). That is, the metal material in the portion near one end in the axial direction (the upper portion in FIGS. 8 to 9 and the portion in FIG. 9) of the two positions with fine hatching in FIG. A metal material is bulged in a portion closer to the center (the lower portion in FIGS. 8 to 9 and the second portion in FIG. 9). The finish molding pressing portion 54 of the finish molding punch 50 has a large protruding amount in the axial direction at a portion near the inner diameter (the inner diameter portion is a flat surface in a direction perpendicular to the central axis of the finish molding punch 50. Yes, it gradually decreases at the portion closer to the outer diameter (the outer diameter-side half is a convex curved surface whose cross-sectional shape is a quarter arc). Similarly to the preforming punch 46, the finish molding punch 50 also includes a cored bar portion 48a, an intermediate step portion 49a, and an upper large diameter portion 50a. The difference between the finish molding punch 53 and the preforming punch 46 is only the shape of the finish molding pressing portion 54, the core metal portion 48a, the intermediate step portion 49a, and the upper large diameter portion. The shape, size, and function of 50a are the same as those of the core metal part 48, the intermediate step part 49, and the upper large diameter part 50 (see FIG. 6) of the preforming punch 46.

As the finish forming punch 53 is pushed in, the metal material in the portion C shown in FIG. 9 is moved to the second portion shown in FIG. As shown in (B), the final intermediate portion is provided with a small-diameter portion 52 (second small-diameter portion described in claims) that is a flat surface in which a portion closer to the inner diameter exists in a direction perpendicular to the central axis. Let it be material 9a.
In the case of this example, in order to make the small-diameter portion 52, after forming the preliminary small-diameter portion 51 having the inner-diameter side end projecting toward one end in the axial direction, the inner diameter of the preliminary small-diameter portion 51 is formed. Since the close-down portion is crushed in the axial direction to form the small diameter portion 52, a thinned portion is unlikely to occur on the other axial end side of the small diameter portion 52. That is, the shape of both side surfaces in the axial direction of the small diameter portion 52 is finished as desired. On the other hand, the step of forming the preliminary small diameter portion 51 is omitted {from the fourth intermediate material 19a shown in FIG. 5E, the final intermediate material 9a shown in FIG. In the case}, as shown by a chain line α in FIG. 9, a thinned portion is likely to occur on the other axial end side of the obtained small diameter portion 52.

  Also in this example, the obtained final intermediate material 9a is taken out from between the mandrel 42a, the fixed die 43a, the movable die 44a, and the finish molding punch 53, and is subjected to the next finishing step ( (Cutting process and grinding process) to complete the outer ring 1 (see the chain line in FIG. 10). Also for the final intermediate material 9a produced by the manufacturing method of this example, the machining allowance in the finishing process is small, and this is shown by a chain line in FIG. 10 due to the efficiency of the finishing process and the improvement in the yield of the material. Such an outer ring 1 having an undercut portion can be manufactured at low cost.

  As in the present invention, after a metal material is plastically processed to form an intermediate material that does not have an undercut portion, the diameter of a part of the cylindrical portion is reduced by plastic processing such as drawing or fluffing. The method of forming the undercut portion is not limited to the manufacture of the race ring member of the wheel bearing rolling bearing unit, and can be used for the manufacture of various metal parts having an undercut portion in the middle portion of the inner peripheral surface.

DESCRIPTION OF SYMBOLS 1 Outer ring 2a, 2b Outer ring track 3 Flange part 4 First small diameter part 5 Main body part 6 Second small diameter part 7 Undercut part 8, 8a Intermediate material 9, 9a Final intermediate material 10 Material 11, 11a First intermediate material 12, 12a Second intermediate material 13, 13a Third intermediate material 14, 14a Cylindrical portion 15, 15a Raw flange portion 16 Bulkhead portion 17 Single side cylindrical portion 18, 18a, 18b Other side cylindrical portion 19, 19a Fourth intermediate material 20, 20a Fifth intermediate material Intermediate material 21 Pre-forming dies 22, 22a Circular hole portions 23, 23a Step portions 24, 24a Concave hole portions 25, 25a Pre-forming punch units 26, 26a Pre-forming inner punches 27 Pre-forming outer punches 28 Central holes 29 Small diameter Part 30, 30a Large diameter part 31, 31a Step part 32, 32a Guide inclined surface 33 Die 3 for finish molding Finish forming punch unit 35 Center hole 36 Mandrel 37 Finish forming inner punch 38 Finish forming outer punch 39 Bottom plate part 40 One side cylindrical part 41 Other side cylindrical part 42, 42a Mandrel 43, 43a Fixed die 44, 44a Movable die 45 Concave part 46 Pre-forming punch 47 Pre-forming pressing portion 48, 48a Core metal portion 49, 49a Intermediate step portion 50, 50a Upper large-diameter portion 51 Pre-small diameter portion 52 Small-diameter portion 53 Finish forming punch 54 Finish forming pressing portion

The present invention relates to a method for manufacturing an outer ring constituting a wheel bearing rolling bearing for rotatably supporting a wheel with respect to a suspension device of an automobile. In particular, the present invention intends to realize a manufacturing method capable of manufacturing an outer ring having a so-called undercut portion having an inner diameter larger than both sides of the portion in the axial direction at an intermediate portion in the axial direction at low cost.

Wheel supporting rolling bearing for rotatably supporting the wheel relative to vehicle suspension system, the outer ring raceway of the double row formed on the inner peripheral surface of the outer ring, the inner ring raceway of the double row formed on an outer peripheral surface of the inner ring By providing a plurality of rolling elements for each row, the relative rotation between the outer ring and the inner ring is made free. Which of these outer ring and inner ring is connected and fixed to the suspension system, and which wheel is supported and fixed to which (which is a stationary wheel and which is a rotating wheel) depends on the design, and any structure exists. To do. The pitch circle diameters of the rolling elements in both rows are often the same as each other, but different structures are also known. In addition, both structures are known depending on the difference in whether the pitch circle diameter in which row is to be increased or the wheel to be supported is a driven wheel or a driving wheel in different cases.

  As described above, there are many specifications for the rolling bearing unit for supporting the wheel, and the necessity for realizing a shape different from the conventional one is increasing due to diversification of requirements in recent years. For example, among the double row outer ring raceways formed on the inner peripheral surface of the outer ring, a shape in which the inner diameter of the outer ring raceway portion near the center with respect to the axial direction is sufficiently larger than the inner diameter of both side portions in the axial direction of the outer ring raceway, That is, there is a case where it is required to provide an outer ring having an undercut portion at an axially intermediate portion of the inner peripheral surface. In any case, the outer ring is made of a metal material such as medium carbon steel, but if an outer ring having an undercut portion as described above on the inner peripheral surface is made by a conventional method, the cost increases. It is difficult to ensure sufficient durability. This point will be described with reference to FIG.

  The shape of the outer ring 1 to be manufactured is indicated by a chain line in FIGS. This outer ring 1 has a main body portion formed in a substantially cylindrical shape, and double row angular outer ring raceways 2a and 2b are arranged at two positions apart from each other in the axial direction on the inner peripheral surface. Each has a flange portion 3 in the middle of the direction. Both the outer ring raceways 2a and 2b are formed on both axial side surfaces of the first small-diameter portion 4 having a smaller inner diameter, provided in the axially intermediate portion of the inner peripheral surface of the outer ring 1. The shape described above is the same as that of the outer ring of a wheel bearing rolling bearing unit that has been generally used in the past, and can be produced without any particular problems by the conventional manufacturing method. In particular, in the case of the outer ring 1 shown in FIG. 10, the diameter of one end portion in the axial direction (upper end portion in FIG. 10) of the cylindrical main body portion 5 is made smaller than the diameter of the intermediate portion in the axial direction or the other end portion. Thus, this portion is the second small diameter portion 6. As the second small diameter portion 6 is provided, the portion between the second small diameter portion 6 and the first small diameter portion 4 has an inner diameter larger than those of the first and second small diameter portions 4 and 6. A large undercut portion 7 is obtained. Based on the presence of such an undercut portion 7, it is difficult to reduce the manufacturing cost of the outer ring 1 and to ensure durability.

  That is, in general, the outer ring 1 is manufactured by performing a forging process, which is a kind of plastic working, on a cylindrical material made of medium carbon steel and making it an intermediate material close to the shape of the outer ring after completion. The intermediate material is subjected to a cutting process such as cutting and grinding to obtain the outer ring 1 having a desired shape and surface properties. The forging process is performed by crushing (plastically deforming) the material in the axial direction between a receiving die that moves in the axial direction of the material and a pressing die. When the intermediate material has a shape portion close to the undercut portion 7 (a portion recessed radially outward from the inner peripheral surface as compared to the portion between the end openings), after the forging process as described above Of the receiving mold and the pressing mold, the mold obtained by processing the portion cannot be separated from the intermediate material. For this reason, when the outer ring 1 as shown by a chain line in FIG. 10 is manufactured by a conventional method, an intermediate material 8 having no undercut portion as shown in FIG. 8, it is necessary to largely scrape the inner peripheral surface intermediate portion corresponding to the undercut portion 7. For this reason, the labor of processing increases, the yield of materials deteriorates and the manufacturing cost increases, and it becomes difficult to improve the surface properties of both the outer ring raceways 2a and 2b. That is, as the intermediate portion of the inner peripheral surface is greatly scraped, so-called fiber flow cut portions in the metal material are easily exposed on the surfaces of the outer ring raceways 2a and 2b. In addition, among the metal materials constituting the material, a clean portion (a radial intermediate portion of the material) that is advantageous in terms of ensuring the durability of both the outer ring raceways 2a and 2b is designated as the outer ring raceways 2a and 2b. It becomes difficult to expose the part.

  It corresponds to the undercut portion 7 of the outer ring 1 after completion, as shown in FIG. 10B, with respect to the conventional manufacturing method as shown in FIG. If the intermediate material 8a having a larger inner diameter can be produced by plastic working such as forging, all of the above problems can be solved. However, as described above, such an intermediate material 8a cannot be manufactured by a conventional manufacturing method.

  Conventionally, methods described in Patent Documents 1 and 2 are known as a method of manufacturing a metal part having an undercut portion by plastic working such as forging. Among these, in the manufacturing method described in Patent Document 1, a cylindrical portion protruding in the axial direction from the radially intermediate portion of the annular portion is bent inward in the radial direction, whereby a portion closer to the inner diameter of the annular portion. The undercut portion is defined between the cylindrical portion and the tip portion of the cylindrical portion. Moreover, in the manufacturing method described in Patent Document 2, an axial intermediate portion or other end portion of an intermediate material having a large diameter portion at one axial end portion and a cylindrical intermediate portion or other end portion in the axial direction is used. It crushes to an axial direction, forms another large diameter part, and makes an undercut part between this another large diameter part and the said large diameter part.

In the manufacturing method described in Patent Document 1, since the shape of the portion where the undercut portion is provided is limited (limited to the inner diameter side portion of the partial conical cylindrical shape), the outer ring of the wheel support rolling bearing unit is manufactured. Not suitable for. In addition, the manufacturing method described in Patent Document 2 considers that a metal part having an undercut portion existing on the outer peripheral surface is taken into consideration, and the inner peripheral surface such as the outer ring 1 shown in FIG. This is not suitable for the production of the race member of the wheel bearing rolling bearing unit having the undercut portion 7.

JP 2007-125614 A JP 2008-194704 A International Publication No. 2009/096434 Pamphlet

In view of the circumstances as described above, the present invention provides a method for manufacturing an outer ring having an undercut portion at an intermediate portion in the axial direction that has an inner diameter larger than both sides of the portion in the axial direction at a low cost. It was invented to realize.

The outer ring of the rolling bearing unit for supporting a wheel, which is the object of the manufacturing method of the present invention, is made of a metal material in a substantially cylindrical shape, and has an inner diameter smaller than the axially opposite side portions at the axially intermediate portion of the inner peripheral surface. The first small-diameter portion is provided with a second small-diameter portion in a portion axially separated from the first small-diameter portion, and a double row outer ring raceway is provided on both side portions in the axial direction of the first small-diameter portion . The portion between the second small-diameter portions is an undercut portion having an inner diameter larger than those of the first and second small-diameter portions, and a flange is formed on a portion of the outer peripheral surface where the position in the axial direction coincides with the undercut portion. A part is provided .
In particular, the manufacturing method of the outer ring of the rolling bearing unit for wheel support of the present invention is such that the second small-diameter portion does not have the second small-diameter portion and the undercut portion by first plastically processing a metal material. And the part which should become an undercut part is made into a cylindrical part, and the intermediate material provided with the raw flange part in the outer peripheral surface of the axial direction intermediate part of this cylindrical part is formed. Thereafter, the inner diameter of the cylindrical portion is reduced by plastic working, which is drawing , to form the second small diameter portion and the undercut portion .

After forming the intermediate material in this way, in order to form the second small diameter portion and the undercut portion, the lower end of the small diameter portion provided at the upper end portion with the intermediate material set on a preforming die. And a large-diameter portion provided in the intermediate portion are continuously provided by a step portion, and a guide inclined surface that is inclined in a direction in which the inner diameter increases toward the lower side is provided at the lower end opening of the large-diameter portion. A preforming punch unit having a molding outer punch is pressed against the intermediate material. Thus, plastic working (drawing) is performed in which at least a part of the cylindrical portion is formed into a partially conical cylindrical shape that is inclined in a direction in which the diameter decreases as it goes upward .
When carrying out the method of manufacturing the outer ring of the rolling bearing unit for supporting a wheel according to the present invention as described above, specifically, as in the invention described in claim 2, first, a cylindrical material made of metal is used as a shaft. By squeezing from both sides in the direction, a preliminary intermediate material having a pair of circular concave holes opened on both end faces and a partition wall partitioning the circular concave holes is formed. Thereafter, a central portion of the partition wall is punched out to form a circular hole, and a portion near the outer diameter of the partition wall remaining around the circular hole is defined as a first small diameter portion.
Further, when the invention described in claim 2 is carried out, preferably, as in the invention described in claim 3, the central portion of the partition wall is punched to form a circular hole (the same process). The inner diameter of the portion close to the opening of one of the circular concave holes is reduced, and the second small diameter portion and the undercut portion are included. Form.

According to the manufacturing method of the outer ring of the rolling bearing unit for supporting a wheel of the present invention configured as described above, an undercut portion having an inner diameter larger than both sides of the portion in the axial direction is provided in the intermediate portion in the axial direction. The outer ring which has it can be manufactured at low cost. That is, by subjecting a metal material such as medium carbon steel to plastic processing such as forging, it can be processed into an intermediate material having a shape close to the completed state including the undercut portion. For this reason, it is not necessary to greatly cut off the intermediate portion of the inner peripheral surface of the intermediate material, and the manufacturing cost can be reduced by reducing the labor of processing and improving the yield of the material. Further, since the intermediate material needs to an inner peripheral surface middle portion largely scraped of no cutting of the fiber flow, or exposed on the surface portion of the outer ring raceway of the double row provided on the inner peripheral surface of the outer ring, or It becomes easy to prevent the non-clean parts in the material from being exposed to both outer ring raceway parts.

Sectional drawing which shows the 1st example of embodiment of this invention in process order. Sectional drawing which shows the preliminary process for shrinking | reducing the diameter of the one end part of an intermediate material with the state (A) just before a process start, and the state (B) just after completion | finish of a process. Sectional drawing which similarly shows finish processing with the state (A) just before a process start, and the state (B) just after completion | finish of a process. Sectional drawing similar to FIG. 2 which shows the 2nd example of embodiment of this invention. Sectional drawing which shows one example of the reference example regarding this invention in order of a process. Sectional drawing which shows the preliminary process for moving the metal material of the one end part inner diameter part of an intermediate material to the axial direction intermediate part in the state (A) just before a process start, and the state (B) just after completion | finish of a process. The X section expanded sectional view of (B) of Drawing 6 for explaining the movement state of the metal material accompanying this preliminary processing. Sectional drawing which shows the finishing process for moving the metal material of the one end part inner diameter part of an intermediate material to the axial direction intermediate part in the state (A) just before a process start, and the state (B) just after completion | finish of a process. The Y section expanded sectional view of FIG. 8 (B) for demonstrating the movement state of the metal material accompanying this finishing process. The partial cross section which shows each when the outer ring used as the object of the manufacturing method of this invention is made with the conventional manufacturing method (A), and when it is made with the manufacturing method of this invention (B).

[First example of embodiment]
1 to 3 illustrate a first example of an embodiment of the present invention corresponding to claims 1 and 2. In the manufacturing method of this example, as shown in FIG. 1G, the final intermediate material 9 having a larger inner diameter corresponding to the undercut portion 7 (see FIG. 10) of the finished outer ring 1 is plasticized. It is made by forging which is a kind of processing. The shape of the final intermediate material 9 is basically the same as that of the intermediate material 8a shown in FIG. The forging process described below, which sequentially plastically deforms the material 10 to form the final intermediate material 9, is performed by heating (heating the material to be processed or the intermediate material at each stage to a temperature exceeding 900 ° C. It is preferable that the processing force (capacity of the press machine) is reduced and the work piece is less susceptible to damage such as cracks. However, depending on the shape and dimensions of the workpiece, it can be performed warmly (in a state where the workpiece is heated to 600 to 900 ° C.). Furthermore, the initial stage processing with relatively little change in the shape of the workpiece can be performed cold depending on the dimensions of the workpiece.

  In the case of the manufacturing method of the present example in order to produce the final intermediate material 9 as described above, first, a long material is cut into a predetermined length to obtain a cylindrical shape as shown in FIG. Material 10 is obtained. Next, by crushing the material 10 in the axial direction to reduce the axial dimension and to increase the outer diameter, the outer diameter of the central portion in the axial direction as shown in FIG. The thickest disc-shaped first intermediate material 11 is the largest.

Next, the first intermediate material 11 is subjected to a first-stage rough forming process to obtain a second intermediate material 12 as shown in FIG. The rough finishing process is performed by forging process in which the first intermediate material 11 is crushed between a pressing mold and a receiving mold that move in the axial direction.
The second intermediate material 12 thus produced is then subjected to a second stage of rough forming to obtain a third intermediate material 13 as shown in FIG. The third intermediate material 13 includes a raw flange portion 15 on the outer peripheral surface of the cylindrical portion 14 and a partition wall portion 16 on the inner diameter side portion. Of the cylindrical portion 14, with respect to the one-side cylindrical portion 17 existing on one side (lower side in FIG. 1) with respect to the axial direction from the bare flange portion 15, the diameter and thickness dimension in the radial direction are set to the final intermediate material 9. The diameter and the thickness dimension of the corresponding part are the same. On the other hand, with respect to the other cylindrical portion 18 existing on the other side (upper side in FIG. 1) in the axial direction than the raw flange portion 15 in the cylindrical portion 14, the diameter of the final intermediate material 9 is the same. Is larger than the diameter of the corresponding part, and the thickness dimension in the radial direction is smaller than the thickness dimension of the corresponding part. In addition, the inner diameter side part of the said cylindrical parts 17 and 18 is equivalent to the circular recessed hole part described in the claim.
Such a third intermediate material 13 is subjected to a piercing (punching by pressing) process for punching and removing the central portion excluding the outer diameter side end portion of the partition wall portion 16, as shown in FIG. Such a fourth intermediate material 19 is used. The circular center hole 35 formed by the piercing process corresponds to the first small diameter portion described in the claims.

None of the first to fourth intermediate materials 11 to 13 and 19 produced by the above processing has an undercut portion that obstructs the retraction of the mold (between the first small diameter portion and the openings at both ends). In addition, there is no portion having an inner diameter smaller than that of the first small diameter portion). Therefore, for example, it can be easily processed by a well-known forging method described in Patent Document 3 and the like. For this reason, illustration and description of the specific structure and operation of a mold or the like used in the processing method from the material 10 to the fourth intermediate material 19 are omitted.

  The fourth intermediate material 19 is subjected to diameter reduction processing by forging, which is a feature of the present invention, on the other side cylindrical portion 18, through the fifth intermediate material 20 shown in FIG. The final intermediate material 9 shown in FIG. Hereinafter, the process of using the fourth intermediate material 19 as the fifth intermediate material 20 and further using the fifth intermediate material 20 as the final intermediate material 9 will be described in detail with reference to FIGS.

  First, in order to process the fourth intermediate material 19 into the fifth intermediate material 20, as shown in FIG. 2A, the fourth intermediate material 19 is secured to a base of a press machine. Set on the molding die 21. The preforming die 21 has a circular hole portion 22 into which the one-side cylindrical portion 17 of the fourth intermediate material 19 is fitted with no gap at the center, and a step portion 23 for abutting the end surface of the one-side cylindrical portion 17. And a recessed hole portion 24 for accommodating the raw flange portion 15 on the outer peripheral surface of the fourth intermediate material 19. When the fourth intermediate material 19 is set in such a preforming die 21, the preforming punch unit 25 provided above the preforming die 21 is moved down to the other cylindrical portion 18. At the same time, the thickness of the other cylindrical portion 18 in the radial direction is increased.

  The preforming punch unit 25 is formed by fixing a preforming inner punch 26 and a preforming outer punch 27 concentrically with each other to the lower surface of the ram of the press machine. Of these, the outer diameter of the preforming inner punch 26 is smaller than the inner diameter of the other cylindrical portion 18 to be reduced, and the fifth intermediate material 20 is obtained by reducing the diameter of the other cylindrical portion 18. The size is commensurate with the inner diameter of the other cylindrical portion 18a (slightly smaller than the inner diameter when springback is considered, or the same as the inner diameter when not necessary). The preforming outer punch 27 has an annular shape as a whole, and has a stepped center hole 28 having a circular cross section. The central hole 28 is formed by connecting a lower end portion of the small diameter portion 29 provided at the upper end portion and an upper end portion of the large diameter portion 30 provided at the intermediate portion by the step portion 31, and further, opening the lower end of the large diameter portion 30. The part is provided with a guide inclined surface 32 that is inclined in a direction in which the inner diameter increases as it goes downward. Of these, the inner diameter of the large-diameter portion 30 is commensurate with the outer diameter of the other cylindrical portion 18a of the fifth intermediate material 20 (in consideration of springback, it is slightly smaller than this outer diameter, and should be taken into consideration). If not, it is the same as this outer diameter). Further, the inner diameter of the lower end portion of the guide inclined surface 32 is larger than the outer diameter of the end surface of the other cylindrical portion 18 to be reduced in diameter.

In order to manufacture the fifth intermediate material 20, as described above, the fourth intermediate material 19 is set on the preforming die 21 as shown in FIG. The preforming punch unit 25 is lowered with a large force together with the ram of the press machine. Then, the said other side cylindrical part 18 approachs into the said large diameter part 30, being guided by the said guide inclined surface 32, and reducing the diameter, The said 5th intermediate material 20 provided with the said other side cylindrical part 18a. To be processed. The thickness dimension in the radial direction of the other cylindrical portion 18a of the fifth intermediate material 20 is thicker than the thickness dimension in the same direction of the other cylindrical portion 18 of the fourth intermediate material 19 by the reduced diameter. Become. Thus, in the case of this example, the thickness of the other cylindrical portion 18 having a thickness smaller than the thickness (predetermined value) of the other cylindrical portion 18a to be manufactured is reduced and the thickness is increased. Therefore, it is easy to reduce the diameter of the other cylindrical portion 18. 1 (E) → (F) in FIG. 1 and (A) → (B) in FIG. 2, the end face of the other cylindrical portion 18a is The stepped portion 31 of the center hole 28 of the preforming outer punch 27 remains separated. The reason for this is to prevent the thickness of the other cylindrical portion 18a from becoming excessively large so that the following finish forming operation for reducing the diameter can be easily performed.

As described above, if the fourth intermediate material 19 is pressed between the preforming die 21 and the preforming punch unit 25 to obtain the fifth intermediate material 20, then the fifth intermediate material 20 is obtained. As shown in FIG. 3, the fifth intermediate material 20 is pressed between the finish molding die 33 and the finish molding punch unit 34 to obtain the final intermediate material 9. The basic structure of the finish molding die 33 and the finish molding punch unit 34 is the same as that of the preforming die 21 and the preforming punch unit 25. However, the finish forming die 33 is fitted in the center hole 35 of the fourth intermediate material 19 to the fifth intermediate material 20 (a circular hole formed by punching the partition wall portion 16) without a gap. The mandrel 36 is provided. In a state where the fifth intermediate material 20 is set on the finish molding die 33, the tip portion (lower half) of the one-side cylindrical portion 17 of the fifth intermediate material 20 is a cylinder provided on the finish molding die 33. It is accommodated in a space (cavity) defined by the inner peripheral surface of the portion 22a, the upper surface of the stepped portion 23a, and the outer peripheral surface of the base end portion of the mandrel 36. Further, the front half (upper half) of the mandrel 36 is fitted into the center hole 35 without a gap.

  When the finish molding punch unit 34 is lowered from this state, the other cylindrical portion 18a is guided by the guide inclined surface 32a and enters the large diameter portion 30a while reducing its diameter, and this other cylindrical portion is introduced. The final intermediate material 9 including the other cylindrical portion 18b having a smaller diameter and a larger thickness than the portion 18a is processed. The other cylindrical portion 18b corresponds to the second small diameter portion described in the claims. In this way, in the finish molding using the fifth intermediate material 20 as the final intermediate material 9, unlike the above-described preliminary molding, the end surface of the other cylindrical portion 18b is used as the inner punch for finish molding. 37 and the step forming portion 31 a provided on the finish forming outer punch 38 constituting the finish forming punch unit 34. The other cylindrical portion 18b is pressed in the axial direction with a sufficiently large force while the inner and outer peripheral surfaces are constrained, and the shape and size of the other cylindrical portion 18b are changed to the finish forming punch. Finish with good precision according to the shape of the inner surface of the unit 34 (obtain a clear undercut shape). During finish molding performed in this manner, a large force (load, stress) is applied to the fifth intermediate material 20 to the final intermediate material 9. However, since the mandrel 36 is fitted in the center hole 35 of the fifth intermediate material 20 to the final intermediate material 9 and the inner diameter side of the one-side cylindrical portion 17 without any gap, the fifth intermediate material 20 to the final intermediate material 9 are inserted. No harmful deformation occurs in the intermediate material 9 other than the other axial side portions 18a to 18b.

The final intermediate material 9 obtained in this step is a material before cutting (turning) and grinding described later, and its shape is not the final shape as a product. Accordingly, since particularly high shape accuracy and dimensional accuracy are not required, it is not always necessary to abut the end surface of the other cylindrical portion 18b against the step portion 31a.
In the above embodiment, the fourth intermediate material 19 shown in FIG. 1E is processed into the final intermediate material 9 shown in FIG. The case where the fifth intermediate material 20 is molded has been described. However, this step can be changed depending on the degree of processing the other cylindrical portion 18 of the fourth intermediate material 19 into the other cylindrical portion 18b of the final intermediate material 9 (a large amount of processing). For example, when the amount of processing is small (the ratio of diameter reduction is low), the processing step of the fifth intermediate material 20 may be omitted, and the fourth intermediate material 19 may be processed directly into the final intermediate material 9. it can. Conversely, when the amount of processing is large (the ratio of diameter reduction is high), the processing from the fourth intermediate material 19 to the final intermediate material 9 can be performed in more stages.

In any case, the final intermediate material 9 obtained is taken out between the finish molding die 33 and the finish molding punch unit 34 and sent to the next finishing process (cutting process and grinding process), The outer ring 1 is completed (see the chain line in FIG. 10). The final intermediate material 9 produced by the manufacturing method of this example has a slightly larger cross-sectional shape than the cross-sectional shape of the outer ring 1 also indicated by a chain line, as shown by the solid line in FIG. . For this reason, the machining allowance in the finishing process is small, and the outer ring 1 having an undercut portion as shown by a chain line in FIG. 10 is obtained by improving the efficiency of the finishing process and improving the yield of the material. Can be manufactured at low cost. Further, it is difficult to expose the cut portion of the fiber flow on the surface of the pair of outer ring raceways, which is advantageous in terms of ensuring the rolling fatigue life of both outer raceways.

[Second Example of Embodiment]
FIG. 4 shows a second example of an embodiment of the present invention corresponding to claims 1 to 3. In the case of this example, the step of processing the fourth intermediate material 19 shown in FIG. 1E is omitted, and the third intermediate material 13 shown in FIG. It is intended to be processed into the shape of the fifth intermediate material 20 shown in FIG. Therefore, in the case of this example, the axial length of the preforming inner punch 26a constituting the preforming punch unit 25a is set to the preforming inner punch 26 used in the first example of the embodiment described above. It is longer than (see FIG. 2) and the outer peripheral edge of the tip is sharpened. Then, as shown in FIG. 4 (A) → (B), the central portion of the partition wall portion 16 existing in the inner diameter side axial direction intermediate portion of the third intermediate material 13 is punched to form a circular center hole 35. At the same time (actually slightly before and after in time), the diameter of the other cylindrical portion 18 is reduced and the thickness dimension of the other cylindrical portion 18 in the radial direction is increased. Then, it is processed into the shape of the fifth intermediate material 20 shown in FIG. Such a processing method of this example can be carried out when the inner diameter of the center hole 35 is smaller than the inner diameter of the other cylindrical portion 18a after processing (this condition is satisfied in most cases).
Other configurations, operations, and effects are the same as those of the first example of the above-described embodiment, and thus overlapping illustrations and descriptions are omitted.

[ Example of Reference Example of the Present Invention ]
5 to 9 show an example of a reference example related to the present invention . In the manufacturing method of the present reference example , as shown in FIG. 5G, the final intermediate material 9a in which the inner diameter of the portion corresponding to the undercut portion 7 (see FIG. 10) of the outer ring 1 after completion is increased, It is made by forging which is a kind of plastic working. The shape of the final intermediate material 9a is basically the same as the intermediate material 8a shown in FIG. 10B and the final intermediate material 9 shown in FIG. However, in FIG. 5 and FIGS. 10 and 1, the axial positions are upside down. Note that the forging process described below, which sequentially plastically deforms the material 10 to obtain the final intermediate material 9a, can be performed hot to reduce the processing force (capacity of the press machine) and to be processed. Although it is preferable from the viewpoint of making it difficult to cause damage such as cracks in the object, it can be performed warmly depending on the shape and dimensions of the workpiece. Furthermore, the initial stage processing with relatively little change in the shape of the workpiece can be performed cold depending on the dimensions of the workpiece.

In the case of the manufacturing method of the present reference example for producing the final intermediate material 9a as described above, first, a long material is cut into a predetermined length to obtain a circle as shown in FIG. A columnar material 10 is obtained. Next, the material 10 is crushed in the axial direction to reduce the axial dimension and perform an upsetting process to expand the outer diameter, so that the outer diameter of the central portion in the axial direction as shown in FIG. The largest intermediate material 11a in the form of a beer barrel is used.

Next, the first intermediate material 11a is subjected to a first-stage rough forming process to obtain a second intermediate material 12a as shown in FIG. The rough finishing process is performed by forging process in which the first intermediate material 11a is crushed between a pressing mold and a receiving mold that move in the axial direction.
The second intermediate material 12a thus produced is then subjected to a second stage rough forming process to obtain a third intermediate material 13a as shown in FIG. The third intermediate material 13a has a bare flange portion 15a on the outer peripheral surface of the cylindrical portion 14a, and a bottom plate portion 39 on one end portion (the lower end portion in FIG. 5D) of the cylindrical portion 14a. Further, a portion closer to one end of the cylindrical portion 14a (portion closer to the bottom plate portion 39 than the raw flange portion 15a) is a middle portion or a portion closer to the other end (the portion opposite to the bottom plate portion 39 with respect to the raw flange portion 15a). ) And a thin wall .

This kind of the third intermediate material 13a, is subjected to piercing (punching by press) process to remove punched across the bottom plate portion 39, such as shown in (E) of FIG. 5, the fourth intermediate material 19a . In the case of this reference example , the diameter and the thickness dimension in the radial direction of the one-side cylindrical portion 40 are the same as the diameter and thickness dimension of the corresponding portion of the final intermediate material 9a. On the other hand, with respect to the raw flange portion 15a in the cylindrical portion 14a, the thickness of the corresponding portion of the final intermediate material 9a with respect to the other cylindrical portion 41 existing on the opposite side of the bottom plate portion 39. It is larger than the size. Further, the outer diameter of the other cylindrical portion 41 is the same as the outer diameter of the corresponding portion of the final intermediate material 9a.
None of the first to fourth intermediate materials 11a to 13a, 19a produced by the above processing has an undercut portion that becomes an obstacle to retreating the mold. Therefore, it can be easily processed by a conventionally known forging method. For this reason, illustration and description are omitted for the specific structure and operation of the mold or the like used in the processing method from the material 10 to the fourth intermediate material 19a.

The fourth intermediate material 19a is subjected to meat gathering processing on the other cylindrical portion 41, thereby passing through the fifth intermediate material 20a shown in FIG. 5 (F) to be the final intermediate material 9a. The processing using the fourth intermediate material 19a as the fifth intermediate material 20a and the processing using the fifth intermediate material 20a as the final intermediate material 9a are both performed with a die having a punch (pressing die) and a mandrel. (Receiving mold) This is performed by a meat gathering process in which a part of the intermediate material is pressed in the axial direction. First, an undercut forming operation using the fourth intermediate material 19a as the fifth intermediate material 20a will be described with reference to FIGS.

  First, as shown in FIG. 6A, the fourth intermediate material 19 a is set on a fixed die 43 provided with a mandrel 42 at the center, and further suppressed by a movable die 44. That is, the one-side cylindrical portion 40 is interposed in a cylindrical space between the outer peripheral surface of the mandrel 42 and the recess 45 formed in the fixed die 43 so as to allow deformation of the one-side cylindrical portion 40. Without insertion (substantially without a gap). The raw flange portion 15 a is accommodated in a recessed hole portion 24 a formed on the upper surface of the fixed die 43. Further, an annular movable die 44 called a floating die is provided in the other cylindrical portion 41 without interposing a gap that allows the outer diameter of the other cylindrical portion 41 to expand (substantially a gap). (Without intervening).

  From this state, as shown in FIGS. 6A to 6B, the preforming punch 46 is pressed against the tip surface of the other cylindrical portion 41. Then, the metal material near the tip of the other cylindrical portion 41 (upward in FIGS. 5 to 6) and at the inner diameter side half is moved toward the axial center of the fourth intermediate material 19a, and the fifth intermediate material is moved. 20a. Of the preforming punch 46, the outer diameter of the preforming pressing portion 47 that presses the tip surface of the other cylindrical portion 41 is larger than the inner diameter of the other cylindrical portion 41 and is also smaller than the outer diameter. That is, the preforming punch 46 is, in order from the front end side (lower end side), a cored bar portion 48 having a small outer diameter near the inner diameter of the other cylindrical portion 41, the preforming pressing portion 47, The outer cylindrical portion 41 has an outer diameter that is larger than the inner diameter and smaller than the outer diameter, and has a tapered outer peripheral surface that is inclined in a direction in which the outer diameter gradually increases toward the base end (upper end). An intermediate step portion 49 and an upper large-diameter portion 50 that can be inserted without rattling on the inner diameter side of the movable die 44 are provided. The preforming pressing portion 47 is provided as a front end surface of the intermediate step portion 49, which is a continuous portion with the intermediate step portion 49 and the core metal portion 48. The preforming pressing portion 47 has a partial arc-shaped cross-sectional shape, and the protruding amount in the axial direction is large at the radially intermediate portion, and is also small at the inner diameter portion and the outer diameter portion.

As the preforming punch 46 is pushed in, the metal material of the portion (a) in FIG. 7 (the upper portion of the two locations with fine hatching in FIG. 7) is pressed downward, The metal material bulges to the lower part (similarly, the lower part of the fine hatching) of the figure. That is, the metal material of the radially inner portion near the opening end (one end, upper end) of the other cylindrical portion 41 is moved radially inward at the axially central portion. Then, as shown in FIG. 5F and FIG. 6B, the fifth intermediate portion is provided with a preliminary small-diameter portion 51 having a shape in which a portion closer to the inner diameter protrudes toward one end side (upper side) in the axial direction. The material 20a is assumed. During the preforming process, the upper large-diameter portion 50 enters the inner diameter side of the movable die 44 without rattling and ensures concentricity between the fourth intermediate material 19a and the preforming punch 46. Further, the cored bar part 48 regulates the inner diameter dimension of the preliminary small diameter part 51 to prevent the preliminary small diameter part 51 from becoming excessively small, thereby obtaining the preliminary small diameter part 51 having a desired dimension. .

As shown in FIG. 8, the fifth intermediate material 20a is subjected to finish molding for making the preliminary small diameter portion 51 into the small diameter portion 52, and is shown in FIGS. 5 (G) and 8 (B). Such a final intermediate material 9a is used. In this finish forming process, as shown in FIG. 8A, the fifth intermediate material 20a is set on a fixed die 43a provided with a mandrel 42a at the center, and further suppressed by a movable die 44a. The shapes, dimensions, and functions of the mandrel 42a, the fixed die 43a, and the movable die 44a are the same as the mandrel 42, the fixed die 43, and the movable die 44 (see FIG. 6) used for the above-described preforming.

From the state in which the fifth intermediate material 20a is set to the mandrel 42a, the fixed die 43a, and the movable die 44a, the finish forming punch 53 is provided as shown in FIGS. The finishing molding pressing portion 54 is pressed against one side surface (upper surface) in the axial direction of the preliminary small diameter portion 51. And among the metal materials which comprise the preliminary | backup small diameter part 51, the metal material which comprises an inner diameter side half part is moved from the axial direction one end side to the center side (from the upper side of FIGS. 8-9 to the lower side). That is, the metal material in the portion near one end in the axial direction (the upper portion in FIGS. 8 to 9 and the portion in FIG. 9) of the two positions with fine hatching in FIG. A metal material is bulged in a portion near the center (the lower portion in FIGS. 8 to 9 and the second portion in FIG. 9). The finish molding pressing portion 54 of the finish molding punch 53 has a large protruding amount in the axial direction at a portion near the inner diameter (the inner diameter portion is a flat surface in a direction perpendicular to the central axis of the finish molding punch 53. Yes, it gradually decreases at the portion closer to the outer diameter (the outer diameter-side half is a convex curved surface whose cross-sectional shape is a quarter arc). Similarly to the preforming punch 46, the finish forming punch 53 also includes a cored bar portion 48a, an intermediate step portion 49a, and an upper large diameter portion 50a. The difference between the finish molding punch 53 and the preforming punch 46 is only the shape of the finish molding pressing portion 54, and the core metal portion 48a, the intermediate step portion 49a, and the upper large diameter portion. The shape, size, and function of 50a are the same as those of the core metal part 48, the intermediate step part 49, and the upper large diameter part 50 (see FIG. 6) of the preforming punch 46.

As the finish forming punch 53 is pushed in, the metal material in the portion C shown in FIG. 9 is moved to the second portion shown in FIG. As shown in (B), the final intermediate material 9a is provided with a small-diameter portion 52 that is a flat surface in which a portion closer to the inner diameter exists in a direction perpendicular to the central axis.
In the case of this reference example , in order to make the small diameter portion 52, the preliminary small diameter portion 51 having the inner diameter side end portion protruding toward one end in the axial direction as described above is formed. Since the portion closer to the inner diameter is crushed in the axial direction to form the small-diameter portion 52, a thin portion is unlikely to occur on the other axial end side of the small-diameter portion 52. That is, the shape of both side surfaces in the axial direction of the small diameter portion 52 is finished as desired. On the other hand, the step of forming the preliminary small diameter portion 51 is omitted {from the fourth intermediate material 19a shown in FIG. 5E, the final intermediate material 9a shown in FIG. In the case}, as shown by a chain line α in FIG. 9, a thinned portion is likely to occur on the other axial end side of the obtained small diameter portion 52.

Also in the case of this reference example , the final intermediate material 9a obtained is taken out from between the mandrel 42a, the fixed die 43a, the movable die 44a, and the finish forming punch 53, and then the next finish processing step. It sends to (a cutting process and a grinding process), and is completed as the outer ring | wheel 1 (refer the dashed line of FIG. 10). With respect to the final intermediate material 9a produced by the manufacturing method of the present reference example, the machining allowance in the finishing process is small, and the efficiency of the finishing process and the improvement of the material yield are shown in FIG. As shown, the outer ring 1 having an undercut portion can be manufactured at low cost .

DESCRIPTION OF SYMBOLS 1 Outer ring 2a, 2b Outer ring track 3 Flange part 4 First small diameter part 5 Main body part 6 Second small diameter part 7 Undercut part 8, 8a Intermediate material 9, 9a Final intermediate material 10 Material 11, 11a First intermediate material 12, 12a Second intermediate material 13, 13a Third intermediate material 14, 14a Cylindrical portion 15, 15a Raw flange portion 16 Bulkhead portion 17 Single side cylindrical portion 18, 18a, 18b Other side cylindrical portion 19, 19a Fourth intermediate material 20, 20a Fifth intermediate material Intermediate material 21 Pre-forming dies 22, 22a Circular hole portions 23, 23a Step portions 24, 24a Concave hole portions 25, 25a Pre-forming punch units 26, 26a Pre-forming inner punches 27 Pre-forming outer punches 28 Central holes 29 Small diameter Part 30, 30a Large diameter part 31, 31a Step part 32, 32a Guide inclined surface 33 Die 3 for finish molding Finish forming punch unit 35 Center hole 36 Mandrel 37 Finish forming inner punch 38 Finish forming outer punch 39 Bottom plate part 40 One side cylindrical part 41 Other side cylindrical part 42, 42a Mandrel 43, 43a Fixed die 44, 44a Movable die 45 Concave part 46 Pre-forming punch 47 Pre-forming pressing portion 48, 48a Core metal portion 49, 49a Intermediate step portion 50, 50a Upper large-diameter portion 51 Pre-small diameter portion 52 Small-diameter portion 53 Finish forming punch 54 Finish forming pressing portion

Claims (6)

  The first small-diameter portion, which is made of a metal material in a substantially cylindrical shape and has an inner diameter smaller than both axial portions at the axially intermediate portion of the inner peripheral surface, is separated from the first small-diameter portion in the axial direction. A track of a rolling bearing unit for supporting a wheel provided with a second small-diameter portion, and a portion between the first and second small-diameter portions being an undercut portion having an inner diameter larger than the first and second small-diameter portions. A method of manufacturing a ring member, which is obtained by plastic processing a metal material, and does not have the second small diameter portion and the undercut portion, and the portion to be the second small diameter portion and the undercut portion is a cylindrical portion. After the intermediate material is formed, the diameter of a part of the cylindrical portion is reduced by plastic working to form the second small diameter portion and the undercut portion. A manufacturing method of a ring member.   By crushing a cylindrical material made of metal from both sides in the axial direction, a preliminary intermediate material having a pair of circular concave holes opened on both end faces and a partition wall partitioning the circular concave holes was formed. 2. The wheel support according to claim 1, wherein the central portion of the partition wall is punched out to form a circular hole, and the portion near the outer diameter of the partition wall remaining around the circular hole is defined as a first small diameter portion. A method for manufacturing a ring member of a rolling bearing unit.   The center part of the partition wall is punched out to form a circular hole, and at the same time, the inner diameter of the portion near the opening of one of the pair of circular concave holes is reduced to form the second small diameter part and the undercut part. The manufacturing method of the bearing ring member of the rolling bearing unit for wheel support described in Claim 2.   The first small-diameter portion, which is made of a metal material in a substantially cylindrical shape and has an inner diameter smaller than both axial portions at the axially intermediate portion of the inner peripheral surface, is separated from the first small-diameter portion in the axial direction. A track of a rolling bearing unit for supporting a wheel provided with a second small-diameter portion, and a portion between the first and second small-diameter portions being an undercut portion having an inner diameter larger than the first and second small-diameter portions. A method of manufacturing a ring member, which is obtained by plastic processing a metal material, and does not have the second small diameter portion and the undercut portion, and the portion to be the second small diameter portion and the undercut portion is a cylindrical portion. After the intermediate material is formed, this cylindrical portion is configured by pushing a punch having an outer diameter larger than the inner diameter of the cylindrical portion and smaller than the outer diameter into the cylindrical portion from the axial end surface of the cylindrical portion. A part of the metal material, this circle And and moved toward the center portion in the axial direction in the inner diameter side of the parts, the manufacturing method of the second small diameter portion and the bearing ring member of a wheel support rolling bearing unit, characterized in that to form the undercut.   By crushing a cylindrical material made of metal in the axial direction, a circular concave hole having an opening at one end surface and an inner diameter of the other end portion being smaller than the intermediate portion or the one end portion and a bottom portion of the circular concave hole After forming the first preliminary intermediate material provided with the bottom plate portion to be closed, this bottom plate portion is punched out and provided with a cylindrical portion penetrating in the axial direction, and the other axial end portion of this cylindrical portion is defined as the first small diameter portion. The manufacturing method of the bearing ring member of the rolling bearing unit for wheel support according to claim 4, wherein an intermediate material is used and then a punch is pushed in from an axial end surface of the cylindrical portion of the intermediate material. From the axial end surface of the cylindrical portion of the intermediate material, first, the amount of protrusion in the axial direction of the portion that presses this axial end surface is large at the radial intermediate portion and is also small at the radially inner end portion. And moving the metal material near the one end of the cylindrical portion to the axial central portion, thereby forming a spare second small diameter portion having a shape in which the portion near the inner diameter protrudes toward the one end in the axial direction. The amount of protrusion in the axial direction of the portion that presses the second small-diameter portion is large in the portion near the inner diameter, and the finish forming punch that gradually decreases in the portion near the outer diameter is pushed in, so that the metal material in the portion near the inner diameter of the preliminary second small-diameter portion The manufacturing method of the bearing ring member of the wheel bearing rolling bearing unit according to claim 5, wherein the second small diameter portion is moved to the axially central portion.

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