JP2014024091A - Manufacturing method for bearing ring member of wheel bearing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method by which a bearing ring of a hub bearing is manufactured at low cost, with reduced cutting volume after being forged and without requiring a split die to be used, the bearing ring having, at an intermediate portion in an axial direction, an undercut portion that has an inner diameter larger than that of both axial-direction sides of the intermediate portion.SOLUTION: The manufacturing method for a bearing ring comprises the steps of: forming an intermediate member 30 having an outward flange 6 that is thicker in an axial direction and smaller in an inner diameter direction than a final shape; squeezing the outward flange in the axial direction without deforming portions other than the outward flange as much as possible to enlarge the outer diameter thereof, thereby forming an undercut shape 23 in a part of an axial-direction part of the inner periphery of the flange.

Description

  The present invention relates to an improvement in a manufacturing method of a bearing ring member constituting a wheel bearing rolling bearing unit, which is used for rotatably supporting a braking rotary member such as a vehicle wheel and a brake disk with respect to a suspension device. . Specifically, the amount of cutting required for making a ring member having a so-called undercut portion whose inner diameter is larger than both axial portions at the axially intermediate portion of the inner peripheral surface is reduced. Thus, the manufacturing cost is reduced.

  2. Description of the Related Art Wheel bearing rolling bearing units are widely used to rotatably support braking rotating members such as automobile wheels and brake disks with respect to a suspension device. As such a wheel-supporting rolling bearing unit, an inner ring rotating type as shown in FIGS. 5 to 6 is generally used, but in some cases, an outer ring rotating type as shown in FIG. 7 is used. Things are also used.

  First, the inner ring rotating type wheel support rolling bearing unit 1 shown in FIG. 5 is for a driven wheel (a front wheel of an FR vehicle and an MR vehicle, a rear wheel of an FF vehicle), an outer ring 2, a hub 3, A plurality of rolling elements 4 and 4 are provided. Of these, the outer ring 2 has two rows of outer ring raceways 5a and 5b at two positions in the axial direction of the inner peripheral surface. In the state, it refers to the center side in the width direction of the vehicle, and the right side in Fig. 5 to 7. On the other hand, the left side in Figs. The same is applied to the outer flange 6. Further, the hub 3 has an outward flange 7 on the outer peripheral surface near the outer end in the axial direction, and double row inner ring raceways 8a and 8b at two positions in the axial direction between the intermediate portion and the inner end portion. Have. A plurality of rolling elements 4, 4 are arranged between the inner ring raceways 8a, 8b and the outer ring raceways 5a, 5b for each row, and the hub on the inner diameter side of the outer ring 2 is disposed. 3 rotations are possible. In the state of use, the outward flange 6 of the outer ring 2 is coupled and fixed to a knuckle that constitutes a suspension device, and the wheel and the braking rotary member are coupled and fixed to the outward flange 7 of the hub 3.

Further, the inner ring rotating type wheel bearing rolling bearing unit 1a shown in FIG. 6 is for driving wheels (the rear wheels of the FR and MR vehicles, the front wheels of the FF vehicles, and all the wheels of the 4WD vehicles). In the case of the wheel-supporting rolling bearing unit 1a shown in FIG. 6, a spline hole 9 is formed in the axial direction at the center of the hub 3a in the radial direction so that the drive shaft is spline-engaged in use. .
Further, the outer ring rotating type wheel bearing rolling bearing unit 1b shown in FIG. 7 is for a driven wheel, and includes a pair of inner rings 10, 10, a hub 11, and a plurality of rolling elements 4, 4. Prepare. Of these, the pair of inner rings 10, 10 each have a single row of inner ring raceways 8a, 8b on the outer peripheral surface, and are arranged side by side in the axial direction. The hub 11 has double-row outer ring raceways 5a and 5b at two positions in the axial direction of the inner peripheral surface, and an outward flange 7 at a portion near the outer end in the axial direction of the outer peripheral surface. Then, a plurality of the rolling elements 4, 4 are arranged between the outer ring raceways 5a, 5b and the inner ring raceways 8a, 8b for each row, and the outer diameters of the inner races 10, 10 are arranged. The hub 11 can be rotated on the side. In the state of use, both the inner rings 10 and 10 are externally fitted and fixed to an axle provided in the suspension device, and the wheels and the braking rotating member are coupled and fixed to the outward flange 7 of the hub 11.
In the case of the rolling bearing units 1, 1 a, 1 b for supporting the wheels described above, balls are used as the rolling elements 4, 4, but the rolling bearing units for supporting the wheels for heavy vehicles are used. In some cases, a tapered roller may be used as the rolling element.

Double-row outer ring raceways 5a and 5b are arranged at two positions in the axial direction of the inner peripheral surface of the bearing ring members such as the outer ring 2 and the hub 11 constituting the wheel bearing rolling bearing units 1, 1a and 1b described above. The bearing ring member having the outward flanges 6 and 7 at positions close to one axial direction of the outer peripheral surface is formed by subjecting a metal material to forging and then finishing such as cutting and grinding. It is done. A method of making a race ring member by such forging has been widely known, for example, as described in Patent Documents 1 and 2.
Next, according to an example of a conventional method of manufacturing a ring member, double row outer ring raceways 5a and 5b are arranged at two positions in the axial direction of the inner peripheral surface as shown in FIGS. Of these, the manufacturing method of the outer ring 2 in which the outward flange 6 is formed at a position overlapping with the outer ring raceway 5a on one axial side (the upper side in FIGS. 8 to 9) in the radial direction will be described as an example. FIG. 10 is added to the description.

In order to manufacture such an outer ring 2, first, a metal columnar raw material 12 as shown in FIG. 10A is prepared.
Then, in the first upsetting process, the raw material 12 is crushed in the axial direction to obtain a first intermediate material 13 as shown in FIG. The first intermediate material 13 has a shape such as a beer barrel or a thick disk shape in which the outer diameter of the intermediate portion in the axial direction is larger than the outer diameter of both end portions in the axial direction.
When such a first intermediate material 13 is obtained, both axial end surfaces of the first intermediate material 13 are surrounded by a rough forming die in the subsequent rough forming step. A pair of rough forming pressing punches is pressed against the center of the first intermediate material 13 to cause plastic deformation. Then, a second intermediate material 14 as shown in FIG. 10C is obtained. The second intermediate material 14 includes a pair of recesses 15a and 15b that open on both axial end surfaces, a partition wall 16 that exists between the bottoms of the recesses 15a and 15b, and one axial side of the outer peripheral surface ( And an outward flange 6 formed so as to protrude radially outward at a position close to the upper side of FIG.

When such a second intermediate material 14 is obtained, both ends of the second intermediate material 14 in the axial direction are surrounded by a finish forming die in the subsequent finish forming step. Press a pair of finish forming press punches onto the surface. As a result, the partition wall 16 is crushed in the direction of reducing the thickness, and the shape of the cylindrical portion 17 existing around the partition wall 16 is changed to the shape of the outer ring 2 shown in FIGS. Get closer. And the 3rd intermediate material 18 as shown to (D) of FIG. 10 is obtained.
When such a third intermediate material 18 is obtained, in the subsequent punching step, the partition wall portion 16 of the third intermediate material 18 is punched and removed except for the outer peripheral edge portion, so that FIG. A fourth intermediate material 19 as shown in FIG.
When such a fourth intermediate material 19 is obtained, the burrs 20 remaining on the outer peripheral edge of the outward flange 6 of the fourth intermediate material 19 are removed in the subsequent deburring step, so that ( A fifth intermediate material 21 as shown in F) is obtained.
Thereafter, the outer ring 2 shown in FIGS. 8 to 9 is completed by performing finishing processing such as cutting or grinding by turning or the like on each part of the fifth intermediate material 21.

  By the way, there are many specifications for the rolling bearing unit for supporting the wheel, and further, due to diversification of demands in recent years, there is an increasing need to realize a shape different from the conventional one. 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. More specifically, in the outer ring rotating type wheel support rolling bearing unit 1b shown in FIG. 7 described above, the inner diameter of the cylindrical portion 22 called the pilot portion provided on the outer end portion in the axial direction of the hub 11 There is a specification to make it smaller than the inner diameter of the outer ring raceway 5a on the outer side in the direction. In the case of such a specification, a portion between the cylindrical portion 22 and the outer ring raceway 5a becomes an undercut portion having an inner diameter larger than both axial side portions. When the bearing ring having such an undercut portion is manufactured by the conventional manufacturing method shown in FIG. 10, the cost increases. This point will be described with reference to FIGS.

  If the hub 11a to be manufactured has a general shape as shown by a chain line in FIG. 11, the fifth intermediate material 21a having a shape as shown by a solid line in FIG. 11 is obtained by the method shown in FIG. Then, the fifth intermediate material 21a may be cut for finishing. Since the amount of cutting at the time of finishing is not particularly large, the yield of the material is not particularly deteriorated.

  On the other hand, when the hub 11b having the shape as shown in FIG. 12 is manufactured, the amount of cutting in finishing is increased, and the yield of the material is deteriorated. The hub 11b has an inner diameter of a cylindrical portion 22a provided at an outer end in the axial direction smaller than an inner diameter of the outer ring raceway 5a on the outer side in the axial direction, and a portion between the cylindrical portion 22a and the outer ring raceway 5a is The undercut portion 23 has an inner diameter larger than both axial side portions.

That is, the hub 11b as shown in FIG. 12, than the inner diameter _{R 23} of the outer ring 5a portion serving as the undercut portion 23, the inner diameter _{R 22} of the cylindrical portion 22a which is a second small diameter portion, and a first small-diameter portion The inner diameter R ₂₄ of the shoulder portion 24 existing between the double row outer ring raceways 5a and 5b is small (R ₂₃ > R ₂₂ , R ₂₄ ). In the case of such a shape having the undercut portion 23, the conventional method shown in FIG. 10 cannot form a shape close to the hub 11b only by forging by the convenience of extracting the mold in the axial direction. In order to manufacture the hub 11b, an intermediate material 25 having a shape indicated by a solid line in FIG. 13 is formed by forging, and then the intermediate material 25 is cut, so that a portion between the solid line and the chain line in FIG. To be the hub 11b.

  As is clear from comparison between the solid line and the broken line in FIG. 13, if the undercut portion 23 exists, it is necessary to largely scrape the intermediate portion of the inner peripheral surface of the intermediate material 25 at a portion corresponding to the undercut portion 23. There is. For this reason, the processing time becomes long, and the yield of the material deteriorates to increase the manufacturing cost.

  The inner diameter of the portion corresponding to the undercut portion 23 of the hub 11 after completion as shown by a chain line in FIGS. 12 and 13 with respect to the conventional manufacturing method as shown in FIG. If the intermediate material having a large thickness can be produced by plastic working such as forging, all of the above problems can be solved. However, as described above, the conventionally known forging method cannot produce the intermediate material as described above.

  Conventionally, methods described in Patent Documents 3 to 7 are known as methods for manufacturing a metal part having an undercut portion by plastic working such as forging. Among these, in the manufacturing method described in Patent Document 3, the cylindrical portion protruding in the axial direction from the radial intermediate portion of the cylindrical portion is radially reduced inwardly, whereby the axial direction of the cylindrical portion is reduced. An undercut portion is formed at a position near the middle. In addition, in the manufacturing method described in Patent Document 4, 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. Another large diameter portion is formed by crushing in the axial direction, and an undercut portion is defined between the another large diameter portion and the large diameter portion.

JP 2005-83513 A International Publication No. 2009/096434 Pamphlet JP 2007-125614 A JP 2008-194704 A German Patent Publication DE 199 14 969 German Patent Publication DE102007016071 Japanese Patent Application No. 2011-155346

  In the manufacturing method described in Patent Document 3, the shape of the portion where the undercut portion is provided is limited (limited to the inner diameter side of the conical portion), so that the bearing ring member of the wheel bearing rolling bearing unit is manufactured. Not suitable for. In addition, the manufacturing methods described in Patent Documents 4 to 6 consider that a metal part having an undercut portion existing on the outer peripheral surface is taken into consideration, and the inner periphery like the hub 11b shown in FIG. It is not suitable for the production of the race member of the wheel bearing rolling bearing unit having the undercut portion 23 on the surface.

  In the manufacturing method described in Patent Document 7, an undercut portion can be formed on the inner peripheral surface, but it is necessary to constrain the outer periphery of the cylindrical portion with a mold before forming the undercut portion. Further, since it is necessary to use a movable mold in which the counter punch and the lower mold move independently, there is a problem that the mold structure becomes complicated, and the setup time and the mold cost increase. In addition, in the process of forming the shape shown in FIG. 1C of Patent Document 7, it is necessary to form a thin and deep cylindrical portion by forward extrusion, but such forward extrusion processing has a very large cross-sectional area reduction rate. Therefore, the load on the mold is large, and in some cases, the forward extrusion itself may be difficult.

  In view of the circumstances as described above, the present invention can manufacture an outer ring equivalent member having an undercut portion, which has an inner diameter larger than both sides of the portion in the axial direction, at an intermediate portion in the axial direction at a low cost. It aims to provide a simple method.

  The object of the present invention is achieved by the following method.

  The first small-diameter portion that is made of a metal material in a substantially cylindrical shape and has an inner diameter smaller than the axially opposite side portions in the axially intermediate portion of the inner peripheral surface, and the axial direction that is axially spaced from the first small-diameter portion A second small-diameter portion is provided at one end, and a portion between the first and second small-diameter portions is an undercut portion having an inner diameter larger than the first and second small-diameter portions. A method of manufacturing a bearing ring member in which a pair of outer ring raceways are provided in a portion sandwiching the first small diameter portion from both sides in the axial direction, and the first end portion in the axial direction is formed by plastic working a metal material. Compared to the final shape on the outside of the cylindrical part that should be the first small diameter part and the undercut part, and the intermediate part in the axial direction of the material without providing the first small diameter part and the undercut part. An outward flange that is thick in the axial direction and small in the radial direction, and the outward flange After forming an intermediate material having a small cylindrical portion at the end opposite to the cylindrical portion and a partition wall portion serving as a boundary of the inner peripheral surface of the cylindrical portion and the small cylindrical portion, Without changing the shape of the small cylindrical portion and the shape near the other end of the cylindrical portion, this outward flange is crushed in the axial direction with a mold to enlarge the outer diameter, and the inner peripheral surface of the cylindrical portion is A method of manufacturing a bearing ring member, wherein the undercut portion is formed at an axial position corresponding to the outward flange.

  In the present invention, as shown in FIG. 2, in the third intermediate material, which is the shape before the undercut shape is formed, the outward flange has a smaller diameter and a thicker wall than the final shape, and the partition wall portion is a small cylindrical portion. By disposing in the vicinity, the depth of the concave portion of the cylindrical portion is made deeper than before. As a result, the pressing portion of the mold that plastically processes the inner diameter side of the cylindrical portion does not come into contact with the partition wall except in the terminal stage of the compression molding process of the outward flange. Therefore, since no plastic deformation occurs in the inner diameter part, no material is supplied from the inner diameter side toward the outer flange, and when the outer flange is compressed and moved to the outer diameter side, the inner diameter side material is drawn into the outer flange. An undercut shape is formed on the inner diameter part.

  In the present invention, compared to the manufacturing method described in Patent Document 7, it is only necessary to form a thick and shallow cylindrical portion, and therefore, forward extrusion molding is facilitated. In addition, since the movable die is not required for forming the undercut portion, the die structure is simple and time is not required for setup, and low cost can be realized. According to the present invention, even if the outer ring of the hub bearing is such that the portion having the smallest inner diameter as shown in FIG. 12 is a small cylindrical portion or the inner diameter of the small cylindrical portion is significantly smaller than the raceway surface diameter. As shown in FIG. 4, it is possible to significantly reduce the cutting allowance for the inner diameter portion as shown in FIG. 4, and the material cost and the cost associated with the cutting can be greatly reduced.

It is sectional drawing which shows embodiment of this invention in process order. It is sectional drawing shown in the state just before a process start of the process which expands an outer diameter, squeezing the outward flange of a 3rd intermediate material to an axial direction. It is sectional drawing shown in the state immediately after completion of a process of expanding the outside diameter, crushing the outward flange of a 3rd intermediate material to an axial direction. It is drawing which shows an example of the outer ring | wheel of a hub bearing in which the site | part where an internal diameter becomes the minimum is a small cylindrical part, or the internal diameter of a small cylindrical part is significantly smaller than a track surface diameter. It is sectional drawing which shows the 1st example of the rolling bearing unit for wheel support incorporating the outer ring | wheel of the hub bearing which can become the object of the manufacturing method of this invention. It is sectional drawing which shows the 2nd example. It is sectional drawing which shows the 3rd example. Sectional drawing which shows an example of the outer ring | wheel which has a general shape. It is a perspective view similarly. It is sectional drawing which shows the process of making the intermediate material for making this outer ring | wheel by forging process in order. It is sectional drawing which shows the relationship between the intermediate material obtained by the forging process, and the outer ring | wheel produced by giving a finishing process to this intermediate material regarding the outer ring | wheel of the hub bearing which has a general shape. It is sectional drawing which shows an example of the shape of the hub (outer ring) used as the object of the manufacturing method of this invention. When manufacturing this hub, it is sectional drawing which shows the relationship between the intermediate material produced with the conventionally forging method, and the hub after completion.

  Embodiments of the present invention will be described with reference to the drawings.

  The embodiment of the present invention will be described with reference to FIGS. In the manufacturing method of this example, as shown in FIG. 1 (F) and FIG. 4, the inner diameter of the portion corresponding to the undercut portion 23 (see the chain line in FIG. 4, FIG. 13 and FIG. 12) of the hub 11b after completion. The final intermediate material 26 having a large thickness is made by forging which is a kind of plastic working. Note that the forging process described below, which sequentially plastically deforms the raw material 12a to form the final intermediate material 26, is performed by hot (the material to be processed or the intermediate material at each stage is heated to a temperature exceeding 900 ° C. It is preferable to carry out the process (in a heated state) from the viewpoint of suppressing the processing force (the capacity of the press) to a small level and making the work piece 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 26 as described above, first, a long material is cut into a predetermined length to obtain a cylindrical shape as shown in FIG. The raw material 12a is obtained. Next, the raw material 12a is crushed in the axial direction to reduce the axial dimension and perform an upsetting process to expand the outer diameter, whereby the outer diameter of the central portion in the axial direction as shown in FIG. Is the first intermediate material 13a having a beer barrel shape.

Next, a rough forming process is performed on the first intermediate material 13a to obtain a second intermediate material 27 as shown in FIG. The rough forming process is performed by a forging process in which the first intermediate material 13a is crushed between a pressing mold and a receiving mold that move in the axial direction. Then, the second intermediate material 27 is defined as one end side in the axial direction (upper side in FIG. 1) as the solid portion 28 and the other end side in the axial direction (lower side in FIG. 1) as the cylindrical portion 29. Such processing of the second intermediate material 27 is conventionally known in the field of metal processing (forging), for example, the first intermediate material 13a is inserted into a die and a receiving die inside a die, for example. It can be easily performed by forward extrusion or backward extrusion that strongly presses in the axial direction. Incidentally, draft angles are provided on both the inner and outer peripheral surfaces of the cylindrical portion 29 to facilitate separation from the mold after the cylindrical portion 29 having a long axial dimension is formed.

  The second intermediate material 27 produced as described above is subsequently subjected to preliminary finishing molding, and the solid portion 28 is plastically deformed, whereby a third intermediate material 30 as shown in FIG. To do. The third intermediate material 30 reduces the axial dimension and outer diameter of the solid portion 28 and forms a recess 31 at the center of one end surface. The small cylindrical portion 32 surrounding the concave portion 31 is the second small diameter portion described in the claims. A partition wall 33 is formed between the bottom surface of the recess 31 and the inner end surface of the inner space of the cylindrical portion 29. Since this partition part 33 is a part used as a scrap, it makes it as thin as possible. Furthermore, the outward flange 6 is formed by shrinking the solid portion 28 and moving the surplus generated by forming the concave portion 31 radially outward. The axial direction position of the outward flange 6 is the radially outer position of the undercut portion 23 [see FIG. 1 (F), FIGS. 2 to 4, 12, 13] formed later. Further, in the third intermediate material 30, the outward flange has a smaller diameter and a thicker wall than the final intermediate material.

  None of the first to third intermediate materials 13a, 27, and 30 produced by the above processing has an undercut portion that obstructs the retraction of the mold in the axial direction (the above-described one formed at one end in the axial direction). There is no portion having an inner diameter smaller than that of the other end opening portion between the small cylindrical portion 32 and the other axial end opening portion). Therefore, for example, it can be easily processed by a forging method described in Patent Document 2 and the like. For this reason, illustration and description are omitted for the specific structure and operation of a mold or the like used in the processing method from the raw material 12a to the third intermediate material 30.

  The third intermediate material 30 is formed by subjecting the outward flange 6 to a compression process in the axial direction by forging, which is a feature of the present invention, and as shown in FIG. The fourth intermediate material 34 having the portion 24 is obtained. During the compression process, the small cylindrical portion 32 and the cylindrical portion 29 are not changed in particular in the radial dimension and the axial dimension, and as a rule remain in their original shape and dimensions.

  The feature of the present invention is to reduce the axial dimension of the outward flange 6 and to move the resulting excess metal material radially outward. At that time, since the upper end surface 45 of the pressing portion 44 does not contact the partition wall portion 33, no material is supplied from the vicinity of the partition wall portion 33 to the outward flange 6, and as a result, the material in the vicinity of the outward flange inner diameter portion moves toward the flange outer peripheral side. The undercut portion 23 is formed by being drawn in. Hereinafter, the process of using the third intermediate material 30 as the fourth intermediate material 34 including the undercut portion 23 and the shoulder portion 24 will be described with reference to FIGS. 2 and 3.

  In order to process the third intermediate material 30 into the fourth intermediate material 34, the third intermediate material 30 is set in a receiving die 35 fixed to a base of a press machine as shown in FIG. The receiving mold 35 is provided with an annular recess 36 into which the cylindrical portion 29 can be fitted without a gap, and a peripheral portion of the annular recess 36 is used as a support surface 37 for abutting one axial surface of the outward flange 6. . The third intermediate material 30 inserts the cylindrical portion 29 into the annular recess 36, abuts one axial surface of the outward flange 6 against the support surface 37, and further places the small cylindrical portion 32 into the pressing die 38. Fits outside. The annular recess 39 of the pressing die 38 is in contact with the small cylindrical portion 32 without a gap, and the flat portion 46 around the annular recess 39 is in contact with the other axial one surface of the outward flange 6. The receiving die 35 is provided with a stepped columnar pressing portion 44 formed by connecting a small-diameter portion 41 on the distal end side and a large-diameter portion 42 close to the base end portion 47 by a curved surface portion 43 inside the annular recess 36. ing. The axial dimension of the pressing portion 44 is in contact with the partition wall 33 when the process of expanding the outer diameter is completed while the outward flange 6 of the third intermediate material 30 shown in FIG. The dimensions to be used.

  Both the outer diameter of the outer peripheral surface 48 of the pressing die 38 and the inner diameter of the inner peripheral surface 49 of the receiving die 35 are cylindrical surfaces whose diameters do not change in the axial direction, and the pressing die 38 and the receiving die 35 are slightly in contact with each other. It is slidable. The pressing die 38 is strongly pressed toward the receiving die 35 by a pressing device (not shown).

  When the third intermediate material 30 is strongly pressed between the receiving die 35 and the pressing die 38, a part of the metal material moves radially outward while the outward flange 6 is crushed in the axial direction. In this plastic working step, the upper end surface 45 of the pressing portion 44 does not contact the partition wall portion 33 of the third intermediate material 30 except for the terminal stage, so that a change in shape occurs in the vicinity of the partition wall portion 33. Further, the shape of the small cylindrical portion 32 is not changed in this step. As a result, since the material for forming the outward flange 6 is not supplied from the partition wall portion 33 and the small cylindrical portion 32, the inner peripheral surface of the cylindrical portion 29 increases as the outer diameter of the outward flange 6 increases. An undercut portion is formed at an axial position corresponding to the outward flange. Moreover, it becomes the 4th intermediate material by which the shoulder part 24 which is the 1st small diameter part described in the claim between the front-end | tip of the said cylindrical part 29 and the said undercut part was formed (refer FIG. 3).

  Subsequently, the fourth intermediate material 34 is subjected to a piercing (punching by pressing) process for punching and removing the entire partition wall 33 to obtain a final intermediate material 26 as shown in FIG. The final intermediate material 26 is sent to the next finishing process (cutting process and grinding process) and completed as the hub 11b (see the chain line in FIG. 4). The final intermediate material 26 produced by the manufacturing method of this example has a slightly larger cross-sectional shape than the cross-sectional shape of the hub 11b also indicated by a chain line, as shown by a solid line in FIG. For this reason, the machining allowance in the finishing process is small, and the hub 11b having the undercut portion 23 as shown in FIG. 12 can be obtained by improving the efficiency of the finishing process and improving the yield of the material. It can be manufactured at low cost.

  In this step, it is not always necessary to finish the molding of the small cylindrical portion 32 in the preliminary finishing molding ((A) to (C) in FIG. 1), but the material that should originally become the small cylindrical portion is the outer flange 6. In order to prevent the small cylindrical portion 32 from forming, it is desirable that the molding of the small cylindrical portion 32 is completed by this step. In this embodiment, the piercing is performed after the undercut portion 23 is formed, but may be performed before the undercut portion 23 is formed.

  In the method of the present application, the undercut portion 23 can be formed large by setting the partition wall portion 33 thin in the axial direction and setting the outer diameter of the outward flange 6 small or thick in the axial direction. . On the contrary, the undercut portion 23 can be made small by setting the partition wall portion 33 thick in the axial direction and setting the outer diameter of the outward flange 6 large or thin in the axial direction.

DESCRIPTION OF SYMBOLS 1, 1a, 1b Rolling bearing unit for wheel support 2 Outer ring 3, 3a Hub 4 Rolling element 5a, 5b Outer ring raceway 6 Outward flange 7 Outward flange 8a, 8b Inner ring raceway 9 Spline hole 10 Inner ring 11, 11a, 11b Hub 12, 12a Raw material 13, 13a First intermediate material 14 Second intermediate material 15a, 15b Recess 16 Partition part 17 Cylindrical part 18 Third intermediate material 19 Fourth intermediate material 20 Burr 21, 21a Fifth intermediate material 22, 22a Cylindrical part 23 Undercut portion 24 Shoulder portion 25 Intermediate material 26 Final intermediate material 27 Second intermediate material 28 Filled portion 29 Cylindrical portion 30 Third intermediate material 31 Recessed portion 32 Small cylindrical portion 33 Bulkhead portion 34 Fourth intermediate material 35 Receiving die 36 Annular recessed portion 37 Bearing part 38 Stamping die 39 Annular recess 40 Substrate part 41 Small diameter part 42 Large diameter part 43 Curved surface part 44 Pushing Part 45 the inner diameter of the inner diameter R ₂₄ shoulder of the inner diameter R ₂₃ undercut of the upper end surface 46 a flat portion 47 base portion 48 within the outer peripheral surface 49 peripheral surface R ₂₂ cylindrical portion

Claims (4)

  The first small-diameter portion that is made of a metal material in a substantially cylindrical shape and has an inner diameter smaller than the axially opposite side portions in the axially intermediate portion of the inner peripheral surface, and the axial direction that is axially spaced from the first small-diameter portion A second small-diameter portion is provided at one end, and a portion between the first and second small-diameter portions is an undercut portion having an inner diameter larger than the first and second small-diameter portions. A method of manufacturing a bearing ring member in which a pair of outer ring raceways are provided in a portion sandwiching the first small diameter portion from both sides in the axial direction, and the first end portion in the axial direction is formed by plastic working a metal material. Compared to the final shape on the outside of the cylindrical part that should be the first small diameter part and the undercut part, and the intermediate part in the axial direction of the material without providing the first small diameter part and the undercut part. An outward flange that is thick in the axial direction and small in the radial direction, and the outward flange After forming an intermediate material having a small cylindrical portion at the end opposite to the cylindrical portion and a partition wall portion serving as a boundary of the inner peripheral surface of the cylindrical portion and the small cylindrical portion, Without changing the shape of the small cylindrical portion and the shape near the other end of the cylindrical portion, this outward flange is crushed in the axial direction with a mold to enlarge the outer diameter, and the inner peripheral surface of the cylindrical portion is A method of manufacturing a bearing ring member, wherein the undercut portion is formed at an axial position corresponding to the outward flange.   The method of manufacturing a bearing ring member according to claim 1, wherein the size of the undercut shape is adjusted by changing an outer diameter and a thickness of the outward flange.   In the step of crushing the outward flange in the axial direction by changing the thickness of the partition wall or by changing the axial dimension of the pressing portion, the partition wall portion is the mold pressing portion. The method for manufacturing a bearing ring member according to claim 1, wherein the amount of plastic deformation is adjusted to adjust the size of the undercut shape.   A race member of a bearing unit for supporting a wheel of an automobile manufactured by the method according to any one of claims 1 to 3.

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