JP2006116550A - Pressing die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently secure the service life of the working surface 22 of a pressing die 17 by improving this pressing die 17 which is used for forming a caulked part 11 in the inner end part of a hub main body 6. <P>SOLUTION: The hardness of the working surface 22 is ≥60HRC (Rockwell C hardness) and mirror finishing is applied to this working surface 22. By adopting this constitution, the above problem is solved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The stamping die according to the present invention includes, for example, a caulking portion at an end portion of the shaft member so that an inner ring externally fitted to an end portion of the shaft member such as a hub main body constituting the wheel supporting hub unit is coupled and fixed to the shaft member. Used to form

  A wheel support hub unit is used to rotatably support the wheel of the automobile with respect to the suspension system. As such a wheel supporting hub unit, Patent Document 1 describes a structure as shown in FIG. This wheel support hub unit supports a hub 2 on the inner diameter side of an outer ring 1 in a freely rotatable manner via a plurality of rolling elements 3 and 3. Out of these, the outer ring 1 has a pair of outer ring raceways 4a and 4b formed on the inner peripheral surface, and a coupling flange 5 for supporting and fixing to the suspension device on the outer peripheral surface.

  The hub 2 is formed by combining a hub body 6 that is a shaft member and an inner ring 7. Of these, the hub body 6 is mounted to support the wheel at a portion closer to the outer end of the outer peripheral surface (the end on the outer side in the width direction of the vehicle when assembled to the vehicle, the left end in FIG. 1 and the lower end in FIG. 2). The flange 8 is also connected to the first inner ring raceway 9a at the intermediate portion, and the inner end (the end at the center in the width direction of the vehicle when assembled to the vehicle, the right end in FIG. 1 and the upper end in FIG. 2). Small-diameter step portions 10 having small diameters are formed. The first inner ring raceway 9a may be formed on the outer peripheral surface of a separate inner ring that is externally fitted to the intermediate portion of the hub body 6.

  The inner ring 7 has a second inner ring raceway 9b on the outer peripheral surface. Such an inner ring 7 is externally fitted to the small-diameter step portion 10 by an interference fit, and is pressed against the step surface 12 of the small-diameter step portion 10 by a caulking portion 11 provided at the inner end portion of the hub body 6. ing. Further, a plurality of each of the rolling elements 3 and 3 is provided between the outer ring raceways 4a and 4b and the inner ring raceways 9a and 9b, respectively, so as to be freely rollable. In the illustrated example, balls are used as the rolling elements 3 and 3. However, in the case of an automobile hub unit that is heavy in weight, a tapered roller may be used instead of the ball.

  Among the wheel supporting hub units configured as described above, the caulking portion 11 is formed by the inner ring 7 that is externally fitted to the small-diameter step portion 10 of the cylindrical portion 13 provided at the inner end portion of the hub body 6. A portion closer to the tip that protrudes in the axial direction than the inner end surface is formed by plastic deformation outward in the diameter direction by a rocking press device 14 as shown in FIG. In the state before the caulking portion 11 is formed, the outer peripheral surface of the inner and outer peripheral surfaces of the cylindrical portion 13 has a cylindrical shape, but the inner peripheral surface has a shape toward the opening. It has a partially conical cylindrical shape with an increasing diameter.

  The rocking press device 14 includes a holder 15, a holding jig 16, and a pressing die 17. Of these, the holder 15 is formed in a bottomed cylindrical shape by a metal material having a sufficiently large rigidity. Then, the center portion of the outer end surface of the hub 2 is supported on the upper surface of the bottom portion 18 via a receiving jig 19 so as to be slightly displaceable. By supporting the central portion of the outer end surface of the hub 2 in such a state, it is possible to prevent an excessive moment load from being applied to the hub 2 when the caulking portion 11 is formed. The holding jig 16 is formed in a substantially annular shape as a whole by combining a pair of jig elements 20, 20 each formed in a semicircular arc shape. Such a holding jig 16 holds the shoulder portion 21 of the inner ring 7 in a state of being connected to the upper end opening of the holder 15 by a connecting means (not shown). Further, the pressing die 17 is provided with a processing surface 22 which is an annular concave curved surface on the lower end surface. Such a pressing die 17 swings about the central axis of the hub 2 (the central axis of the hub 2 is tilted by an angle θ with respect to the central axis of the hub 2). It can be swung around the center).

  When the caulking portion 11 is formed at the inner end portion of the hub body 6, a part in the circumferential direction of the machining surface 22 of the die 17 is formed on a portion in the circumferential direction of the cylindrical portion 13 provided at the inner end portion. Press. In the illustrated example, this pressing force is generated by pressing the hub 2 upward via the holder 15. In this state, the pressing position of the processing surface 22 against the cylindrical portion 13 is moved in the circumferential direction by swinging the pressing die 17. As a result, the work surface 22 is pressed against the cylindrical portion 13 and the cylindrical portion 13 is plastically deformed radially outwardly, partially and continuously in the circumferential direction, so that the caulking is performed. Part 11 is formed. When the caulking portion 11 is formed in this way, the caulking portion 11 is formed by simultaneously performing the operation of plastically deforming the cylindrical portion 13 radially outward as in a general forging process. This caulking portion 11 can be formed with a small processing load as compared with the case of forming.

  By the way, in the case of the conventional pressing die 17 that constitutes the oscillating press device 14 as described above, sometimes the working surface 22 has a short life. When this cause was investigated, in the case of the conventional pressing die 17, the hardness and finish of the processed surface 22 were not managed with particular care {specifically, the material of the pressing die 17 was changed. In the case of tool steel, the hardness of the processed surface 22 is about HRC (Rockwell hardness / C scale) 58 to 62, and the processed surface 22 is finished with a surface roughness Ra (center). It was found that it was caused to be about 0.2 to 0.4 μm (in some cases, the processed eyes could be seen with the naked eye) in terms of line average roughness. That is, there is a close relationship between the life of the processed surface 22 and the hardness and finish of the processed surface 22. In the case of the conventional die 17, the hardness and finish of the processed surface 22 are appropriately set. As a result, it was found that the short-lived die 17 as described above appeared.

JP 2000-2111302 A

  In view of the circumstances as described above, the stamping die of the present invention was invented so that the life of the machined surface can be stably extended by appropriately managing the hardness and finish of the machined surface.

The pressing die of the present invention has an annular processing surface. Then, in a state in which a part of the processing surface in the circumferential direction is pressed against a part of the annular processing portion constituting the workpiece in the circumferential direction, the center axis of the processing surface is oscillated and displaced. The pressing position of the processed surface against the part is moved in the circumferential direction. As a result, the plastic working of the workpiece is partially and continuously advanced in the circumferential direction.
In particular, in the stamping die of the present invention, the hardness of the processed surface is HRC 60 or more, and the processed surface is mirror-finished {the surface roughness after finishing is Ra 0.2 μm or less or Ry (in the maximum height notation). ) Processing that is 0.8 μm or less and can be made invisible with the naked eye. For example, it includes electrolytic polishing as well as free abrasive processing such as lapping, polishing by attaching abrasive grains to a tape, polishing with a grindstone, and superfinishing (vanishing finish, hard turning finish). } Is given.

  In the case of the stamping die of the present invention configured as described above, since the hardness and finish of the processed surface are appropriately managed, the life of the processed surface can be stably extended. In the case of the stamping die of the present invention, since the surface roughness of the processed surface is good (Ra 0.2 μm or less or Ry 0.8 μm or less), when the processed part is plastically deformed by this processed surface, Local stress is unlikely to occur on the surface of the processed part. Moreover, the surface roughness of the processed part after plastic deformation is also improved. Therefore, it is possible to improve the strength and rust prevention of the processed part after plastic deformation.

  As described in claim 2, the stamping die of the present invention is provided at the end of a shaft member constituting a wheel support hub unit (for example, as shown in FIGS. 1 and 2 described above). Can be used to form a caulking portion for connecting and fixing the inner ring.

  In the case where the present invention is carried out and the material of the die is steel, the upper limit value of the hardness of the processed surface is preferably HRC80. This is because the processing cost for increasing the altitude of the processed surface can be suppressed.

Moreover, when implementing this invention, Preferably, after processing a mirror surface finish to a processed surface, even if this processed surface is observed with a stereoscopic optical microscope (10 to 40 times), the processed eyes are not visible The surface of
In this way, the effects of the present invention as described above can be sufficiently obtained.

尚、この表１中、加工面２２の寿命評価を示す３種類の記号のうち、「◎」は、この加工面２２の寿命が前述した従来の押型１７の加工面２２の平均寿命よりも長かった場合を、「〇」は、同じくこの平均寿命と同等だった場合を、「△」は、同じくこの平均寿命よりも短かった場合を、それぞれ示している。 An experiment conducted for confirming the effect of the present invention will be described with reference to FIG. In the experiment, six types of molds 17 (Sample 1), each of which is made of tool steel (for example, alloy tool steel, high-speed tool steel) and whose hardness and finishing method of the machining surface 22 are changed, respectively. ~ 6) were prepared. And the lifetime of the process surface 22 of each of these samples 1-6 was investigated by performing the formation operation | work of the crimping | compression-bonding part 11 with the rocking press apparatus 14 incorporating these each samples 1-6. The experimental results are shown in Table 1 below.

In Table 1, among the three types of symbols indicating the life evaluation of the machined surface 22, “は” indicates that the service life of the machined surface 22 is longer than the average life of the machined surface 22 of the conventional die 17 described above. In this case, “◯” indicates a case where it is equivalent to this average life, and “Δ” indicates a case where it is shorter than this average life.

  As shown in Table 1 above, Samples 3, 5, and 6 having a life evaluation of “」 ”have a hardness of HRC60 or higher on the processed surface 22 and lapping as a mirror finish method for the processed surface 22 ( In this experiment, a finishing method in which the processed surface 22 is manually polished using diamond abrasive grains while rotating the sample, and when the finishing method is performed, the surface roughness of the processed surface 22 becomes good. Since the coefficient of friction with the caulking portion 11 is reduced, adhesion is less likely to occur at the contact portion between the machining surface 22 and the caulking portion 11 during machining. Samples 2 and 4 having a life evaluation of “◯” have a hardness of HRC60 or higher on the machined surface 22, but mirror finish is not adopted as a finishing method of this machined surface {in this experiment, grinding Finish + light lapping (a level of lapping that may be visible to the naked eye)} (sample 2) or lapping is used as the finishing method of the processed surface 22 However, the hardness of the processed surface 22 was less than HRC60 (Sample 4, which may be less than HRC60). Sample 1 having a life evaluation of “Δ” has a hardness of the processed surface 22 of less than HRC60, and does not employ a polishing finish such as lapping as a finishing method of the processed surface 22 {this experiment Then, a grinding finish and a light lap finish (a level of lap finish that may be visible to the naked eye) is adopted}.

  From the above experimental results, in order to stably extend the life of the machined surface 22, the hardness of the machined surface 22 should be HRC 60 or more, and mirror finish should be adopted as a finishing method for the machined surface 22. It could be confirmed.

  When the crimping portion 11 is formed using the pressing die 17 of the present invention, the pressing die 17 is used on the way (for example, about 1/10 to 1/2 of the average life of the pressing die 17). Each time, it is preferable to re-finish the mirror surface of the machining surface 22. In this way, the processed surface 22 that has become rough due to the processing can be made smooth again, and the processed surface 22 can be cracked or the like compared to the case where the mirror surface finishing of the processed surface 22 is not performed again. Damage is less likely to occur. For this reason, the lifetime of this processed surface 22 can be made longer. In other words, more caulking portions 11 can be formed with a single stamping die 17.

Sectional drawing which shows an example of the hub unit for wheel support provided with the crimping part known conventionally. Sectional drawing which shows the state which forms a crimping part with a pressing die.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer ring 2 Hub 3 Rolling element 4a, 4b Outer ring raceway 5 Coupling flange 6 Hub main body 7 Inner ring 8 Mounting flange 9a, 9b Inner ring raceway 10 Small diameter step part 11 Caulking part 12 Step surface 13 Cylindrical part 14 Oscillating press device 15 Holder 16 Holding jig 17 Stamping die 18 Bottom 19 Receiving jig 20 Jig element 21 Shoulder 22 Processing surface

Claims (2)

  It has an annular machining surface, and the center axis of the machining surface is swung while a part of the machining surface in the circumferential direction is pressed against a part of the annular machining part constituting the workpiece. In a pressing die that displaces and moves the pressing position of the work surface against the work part in the circumferential direction, thereby allowing the plastic working of the work part to proceed partly and continuously in the circumferential direction. The stamping die is characterized in that the hardness of the processed surface is HRC60 or more, and the processed surface is mirror-finished.   The inner ring is fitted on a small-diameter step provided on the outer peripheral surface of one end of the shaft member, and the portion protruding from the one end surface of the inner ring at the end of the cylindrical portion that is one end of the shaft member is radially outward. One end surface of the inner ring is held down by a caulking part formed by plastic deformation in the direction, and the cylindrical shape is the work part in order to produce a wheel support hub unit that is coupled and fixed to the shaft member. 2. The pressing die according to claim 1, wherein a portion protruding from one end face of the inner ring at a portion near the tip of the portion is used for plastic deformation in a radially outward direction to form the caulking portion.

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