JP5885547B2 - Ball joint manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a ball joint used in a link mechanism such as a stabilizer connecting rod or a mission control unit of an automobile.

As this type of ball joint, a ball stud having a ball that is a swing center of the link mechanism at the tip of the shaft member, a holder that covers the maximum diameter portion of the ball stud and that is in sliding contact with the spherical surface of the ball, What is composed of is known.

  Japanese Laid-Open Patent Publication No. 9-189322 (Patent Document 1) discloses a method for manufacturing the ball joint. In this manufacturing method, a steel ball for a bearing having a high sphericity is used as the ball, and the holder is formed by casting using the ball as a core. Thereby, the spherical surface of the steel ball for bearing can be transferred to the holder, and the holder has a metal sliding contact surface with high sphericity. Further, the ball stud is completed by electrical resistance welding of the shaft member to the ball after the casting of the holder. For this electric resistance welding, it is necessary to pass a welding current between the ball and the shaft member. However, since the holder cast with the ball as the core is in close contact with the ball, The electrode is not brought into direct contact with the holder, but the electrode is brought into contact with a holder that is in close contact with the ball, whereby a welding current is passed between the ball and the shaft member.

  Further, the metal sliding contact surface of the holder formed as described above is in close contact with the ball due to shrinkage that occurs after casting, and the ball stud cannot be swung with respect to the holder. For this reason, in the ball joint disclosed in Patent Document 1, the ball sliding is applied to the ball stud in the axial direction, and the metal sliding contact surface of the holder formed by casting is pressed by the spherical surface of the ball. Is plastically deformed to form a very small gap between the holder and the ball, thereby separating the two and enabling the ball stud to swing with respect to the holder.

  On the other hand, Japanese Patent Application Laid-Open No. 2004-316771 (Patent Document 2) discloses a ball joint manufacturing method in which a ball and a holder cast as a core are separated by a resin sliding contact member. The resin sliding contact member covers the maximum diameter portion of the ball stud and is in sliding contact with the spherical surface of the ball, and the holder covers the periphery of the resin sliding contact member and holds the resin sliding contact member. The holder is formed by casting using a ball covered with the resin sliding contact member as a core, and the resin sliding contact member is fixed to the holder with a resin sliding contact surface that follows the spherical surface of the ball. Is done.

  The ball stud is formed by electric resistance welding of a shaft member to the ball after casting of the holder, as in the above-mentioned Patent Document 1. However, since a resin sliding contact member exists between the ball and the holder, it is impossible to apply a welding current to the ball using the holder as in Patent Document 1. For this reason, the resin sliding contact member and the holder are provided with a power supply opening, and the power supply electrode is brought into direct contact with the ball through the power supply opening.

  Furthermore, in the ball joint manufacturing method of Patent Document 2, the resin sliding contact member is reheated after completion of casting of the holder, thereby reducing the force with which the resin sliding contact member clamps the ball. The movement of the ball stud with respect to the holder is managed. That is, in the ball joint of Patent Document 2, there is no need to positively form a gap between the ball and the holder by plastically deforming the holder as in Patent Document 1.

JP-A-9-189322 Japanese Patent Application Laid-Open No. 2004-316771

  In the manufacturing method of Patent Document 1, it is not necessary to provide a power supply opening for the holder as in Patent Document 2, and there is an advantage that foreign matter can be prevented from entering from the outside. However, in order to move the ball stud smoothly, it is necessary to apply an external force to the ball stud to plastically deform the metal sliding contact surface of the holder, and this plastic deformation amount affects the motion accuracy of the ball stud. Given this, it was necessary to strictly control this process.

  On the other hand, in the ball joint obtained by the manufacturing method disclosed in Patent Document 2, the resin sliding contact member and the ball are in sliding contact with no gap, and the ball stud can move smoothly. On the other hand, it is necessary to provide the aforementioned power supply opening for the holder and the resin sliding contact member, and this power supply opening is closed by a closing cap after the ball stud is completed in order to prevent foreign matter from entering from the outside. There was a need. The closing cap is fixed to the holder by caulking the peripheral edge of the power supply opening. However, since the other member is fixed to the opening of the holder, the work is fully performed. Even if expected, there was a possibility that the sealing performance between the closing cap and the holder would be insufficient due to unforeseen reasons.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide electric resistance welding of a shaft member to the ball without providing a power supply opening for a holder cast with the ball as a core. It is another object of the present invention to provide a method for manufacturing a ball joint that does not have a metal sliding contact surface with a ball and that can ensure a smooth operation of the ball stud with respect to the holder.

  The ball joint manufacturing method of the present invention that achieves the above-described object has a sliding surface of the ball stud with the ball to cover the maximum diameter portion of the ball, and the spherical surface of the ball is exposed in the opposite direction. A body that covers the periphery of the resin sliding contact member by molding a resin sliding contact member having one opening and a second opening, and casting with the ball and the resin sliding contact member placed thereon as a core. And a blocking portion that covers the spherical surface of the ball protruding from the second opening of the resin sliding contact member and contacts the ball, and is exposed from the first opening of the resin sliding contact member. Forming a holder that is not in contact with the spherical surface, and abutting the shaft member against the ball exposed from the first opening of the resin sliding contact member and bringing the electrode into contact with the shaft member while contacting the ball Ho An electrode is brought into contact with the closed portion of the die, the ball and the shaft member are joined by electric resistance welding to form the ball stud, and a gap forming load is applied to the ball stud in the axial direction, And a step of making the tip concave spherical surface of the closing part non-contact.

  Since the holder is integrally provided with a closing portion that covers the spherical surface of the ball protruding from the second opening of the resin sliding contact member and contacts the ball, the shaft member is electrically resistance welded to the ball. In doing so, it is possible to apply a welding current to the ball from the closed portion by bringing the power feeding electrode into contact with the holder. In other words, the ball stud can be welded without providing a power supply opening for the holder, and a closing cap that closes the power supply opening is not necessary, thereby reducing the number of parts and simplifying the production process. be able to.

  Further, when an axial gap forming load is applied to the ball stud after the ball stud has been welded, the ball stud ball presses the closed portion of the holder that is in contact with the ball stud, and the closed portion is plastic. Deform. At this time, the resin sliding contact member existing between the main body portion of the holder and the ball stud ball is elastically deformed by receiving the gap forming load, but the resin sliding member is removed in a state where the gap forming load is removed. Since the shape of the contact member is restored, the ball is separated from the plastically deformed closed portion, and the ball and the closed portion of the holder are not in contact with each other. Further, before and after the closing portion is plastically deformed, the resin sliding contact member and the ball are kept in contact with no gap. Therefore, the ball stud ball is not in contact with the cast holder at all, and since the ball is in sliding contact with the resin sliding contact member without any gap, it is possible to ensure the smooth operation of the ball stud with respect to the holder. It becomes.

It is front sectional drawing which shows an example of embodiment of the ball joint manufactured by the method of this invention. FIG. 2 is a front view showing a state where a resin sliding contact member is covered on a ball in the ball joint manufacturing method shown in FIG. 1. FIG. 2 is a cross-sectional view showing a state in which a holder is cast using a ball and a resin sliding contact member as a core in the ball joint manufacturing method shown in FIG. 1. FIG. 2 is a front sectional view showing a cast holder in the method for manufacturing the ball joint shown in FIG. 1. FIG. 2 is a front cross-sectional view showing a state in which a shaft member is welded to a ball held by a holder in the ball joint manufacturing method shown in FIG. 1. FIG. 2 is a front cross-sectional view showing a step of forming a gap between the closed portion of the holder and the ball in the method for manufacturing the ball joint shown in FIG. 1. It is front sectional drawing which shows the other example of the process of forming a clearance gap between the closed part of a holder, and a ball | bowl.

  Hereinafter, the ball joint manufacturing method of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows an example of an embodiment of a ball joint manufactured by the method of the present invention. The ball joint includes a ball stud 1 having a ball 10 at the tip of a shaft member 11, a resin sliding contact member 3 that is covered with the ball 10 and that is in sliding contact with the ball 10, and around the resin sliding contact member 3. A holder 2 is molded and the resin sliding contact member 3 is fixed thereto, and the ball stud 1 is pivotably connected to the holder 2 around the ball.

  The ball stud 1 is formed by electric resistance welding of a rod-shaped shaft member 11 to a steel ball for a bearing having a high sphericity that becomes a ball 10. The shaft member 11 is formed with a flange 12 having a seating surface for fixing a body to be attached such as a link, and a male screw 13 is formed on the opposite side of the ball 10 with the flange 12 interposed therebetween. ing. Moreover, the said collar part 12 is formed in the shape of a hexagon nut, and it is possible to fasten the external thread 13 of the said ball stud 1 to to-be-attached bodies, such as a link, using a spanner wrench.

  The resin sliding contact member 3 has a first opening 31 and a second opening 32 through which the spherical surface of the ball 10 is exposed in opposite directions, and is formed in an annular shape, and substantially matches the spherical surface of the ball 10 on the inside. The concave spherical resin sliding contact surface 30 is provided. The shaft member 11 of the ball stud 1 is joined to the spherical surface of the ball 10 exposed from the first opening 31. The resin sliding contact member 3 covers the maximum diameter portion of the ball 10 and covers approximately 2/3 of the spherical surface of the ball 10.

  On the other hand, the holder 2 includes a main body 20 provided around the resin sliding contact member, a fixing portion 21 for coupling the main body 20 to the link, and the resin sliding contact member. The main body part 20, the fixing part 21, and the closing part 23 are integrally formed by die casting of an aluminum alloy or a zinc alloy. Although not shown in FIG. 1, the fixing portion 21 is formed with a female screw so that, for example, a male screw formed at the tip of a rod or the like constituting the link can be coupled. Further, the main body 20 can be directly fixed to the mounted body without providing the fixing portion 21.

  The main body portion 20 is formed in an annular shape outside the resin sliding contact member 3, and the resin sliding contact member 3 is fixed to the main body portion 20. Further, the main body 20 is provided with a holder opening 22 corresponding to the first opening 31 of the resin sliding contact member 3, and the first opening of the resin sliding contact member 3 is provided from the holder opening 22. The peripheral edge of the opening 31 is slightly exposed. That is, the main body 20 of the holder 2 is not in contact with the spherical surface of the ball 10 exposed from the first opening.

  Further, the closing portion 23 of the holder 2 is formed integrally with the main body portion 20 by the above-described casting. The closed portion is in contact with the convex spherical surface of the ball 10 protruding from the second opening 32 of the resin sliding contact member 3 when the holder 2 is cast. A gap is formed between the ball 10 and the concave concave surface 23a of the closing portion 23 that contacts the ball 10, and the ball 10 and the closing portion 23 are kept in non-contact when the ball joint is completed. Yes. That is, when the ball stud 1 swings with respect to the holder 2, the ball 10 is in contact only with the resin sliding contact surface 30 of the resin sliding contact member 3.

  Further, a boot seal 4 is attached between the outer peripheral edge of the main body portion 20 of the holder 2 and the shaft member 11 of the ball stud 1, and a gap between the ball 10 of the ball stud 1 and the main body portion 20 of the holder 2. In addition to preventing dust and dirt from entering the seal pocket 40, a seal pocket 40 for accommodating a lubricant such as grease is formed. Here, the end 41 on the ball stud 1 side of the boot seal 4 is in close contact with the shaft member 11 due to its elasticity, while the end 42 on the holder 2 side is sandwiched between the outer peripheral edge of the holder 2 by a locking ring. Therefore, the ball stud 1 does not come off even when the ball stud 1 swings or rotates. The boot seal 4 is attached to the ball stud 1 and the holder 2 after forming a gap between the tip concave spherical surface 23a of the closing portion 23 and the ball 10 in the final stage of the manufacturing process described later.

  Next, a specific method for manufacturing the ball joint of this embodiment will be described.

  In the first step, the resin sliding contact member 3 is formed and mounted on a bearing steel ball that becomes the ball 10. As an example of the material of the resin sliding contact member 3, polyether ether ketone (manufactured by Victorex / trade name: PEEK) is used, and the thickness thereof is set to about 0.8 mm, for example. FIG. 2 is a front view showing a state where the resin sliding contact member 3 is mounted on the ball 10. The resin sliding contact member 3 is formed in an annular shape having an inner diameter that matches the outer diameter of the ball 10, and has the first opening 31 and the second opening 32 where the spherical surface of the ball 10 is exposed in opposite directions as described above. Have. The inner diameter D2 of the second opening 32 is set to be smaller than the inner diameter D1 of the first opening 31, and the distance H from the center O of the ball 10 to the first opening 31 and the center O of the ball 10 are set. When the distance h from the second opening 32 is compared, H <h. Therefore, the contact area between the resin sliding contact member 3 and the spherical surface of the ball 10 is smaller on the first opening 31 side than the center O of the ball 10 and larger on the second opening 32 side. .

  The inner diameter of the first opening 31 of the resin sliding contact member 3 is determined from the relationship with the movable range of the ball stud 1 relative to the holder 2. However, in consideration of the case where a radial load in a direction perpendicular to the axial direction acts on the ball stud 1, it is preferable that the contact area between the resin sliding contact member 3 and the ball 10 is large. In particular, the inner diameter of the second opening 32 of the resin sliding contact member 3 is preferably set as small as possible. As described above, the inner diameter D2 of the second opening is set smaller than the inner diameter D1 of the first opening. Is preferred.

  As an example of covering the resin sliding contact member 3 with the ball 10, the resin sliding contact member 3 is injection-molded using the ball 10 as a core, and the molding of the resin sliding contact member 3 and the mounting to the ball 10 are performed as one. It is possible to carry out in one process. When the resin sliding contact member 3 is molded using the ball 10 itself as a core in this way, the mounting effort to the ball 10 is omitted, and the spherical surface of the ball 10 is the resin sliding contact surface 30 of the resin sliding contact member 3. Therefore, the resin sliding contact member 3 and the ball 10 are in surface contact with no gap, and the sliding contact state between them can be improved.

  Note that only the resin sliding contact member 3 is formed without using the ball 10 as a core, and the ball 10 is introduced into the resin sliding contact member 3 from the first opening 31 of the molded resin sliding contact member 3. The resin sliding contact member 3 may be attached to the ball 10 by pushing it in.

  Next, the holder 2 is die-cast. In this die casting, as shown in FIG. 3, a ball 10 and a resin sliding contact member 3 attached to the ball 10 are inserted into a core in a pair of upper and lower casting molds 5 and 6. In this state, a molten aluminum alloy or zinc alloy is press-fitted into the cavity 7 in the mold. At this time, the ball 10 is fitted to a concave spherical support seat 60 formed on the mold 6 with the spherical surface exposed from the first opening 31 of the resin sliding contact member 3, and the support seat 60 has a peripheral edge. It contacts the periphery of the first opening 31 of the resin sliding contact member 3. In order to securely fix the ball 10 to the support seat 60, a magnetic attractive force may be applied to the ball 10 from the support seat 60.

  Thereby, as shown in FIG. 4, the holder 2 in which the ball 10 and the resin sliding contact member 3 are wrapped with the alloy is cast. In the cast holder 2, the holder opening 22 is formed at a portion corresponding to the support seat 60 of the mold 6, and the ball 10 is exposed only from the holder opening 22. The holder 2 is not in contact with the ball 10 in the first opening 31 of the resin sliding contact member 3, but the second opening 32 is covered with a closing portion 23 formed integrally with the main body 20. The closing portion 23 is formed with a tip concave spherical surface 23 a that contacts the spherical surface of the ball 10 protruding from the second opening 32. When the holder 2 is cast, the resin sliding contact member 3 attached to the ball 10 is embedded in the main body 20 of the cast holder 2, and the resin sliding contact with the ball 10 is made. The resin sliding contact surface 30 of the contact member 3 and the tip concave spherical surface 23a of the closing portion 23 are formed as one concave spherical surface that is continuous without a step. The concave spherical surface is in contact with the spherical surface of the ball 10 without a gap.

  Next, the shaft member 11 is welded to the ball 10. For such welding, projection welding which is a kind of electric resistance welding is used. Specifically, as shown in FIG. 5, the end surface of the shaft member 11 is pressed against the spherical surface of the ball 10 exposed from the holder opening 22 with a predetermined force F1, while the closing portion 23 of the holder 2 and The electrodes 14 and 15 are brought into contact with the shaft member 11, respectively, and a welding current is supplied to the closing portion 23 and the shaft member 11. An electrode mounting surface 24 is formed on the outer side of the closing portion 23, and the electrode mounting surface 24 has a circular shape centered on the axial center line of the ball stud 1. The electrode 15 is formed in an annular shape and abuts against the flange 12 of the shaft member 1.

  Since the holder 2 is cast with the ball 10 and the resin sliding contact member 3 as a core, as described above, the closed portion 23 of the holder 2 is formed with a concave concave spherical surface 23a to which the spherical surface of the ball 10 is transferred. The tip concave spherical surface 23a is in contact with the spherical surface of the ball 10 without a gap. For this reason, by bringing the electrode 14 into contact with the closed portion 23, a welding current can be passed from the closed portion 23 to the ball 10, and the ball 10 and the shaft member 11 can be electrically resistance welded. It becomes.

  When the electric resistance welding is completed in this way, as shown in FIG. 6, the tip surface of the shaft member 11 is joined to the ball 10, and the ball 10 is connected to the main body of the holder 2 via the resin sliding contact member 3. The ball stud 1 held by the part is completed.

  In order to perform electrical resistance welding between the ball 10 and the shaft member 11, it is necessary that the energization resistance between the closing portion 23 and the ball 10 is smaller than the energization resistance between them. If the current-carrying resistance between the blocking portion 23 and the ball 10 is greater than that between the ball 10 and the shaft member 11, the boundary surface between the blocking portion 23 and the ball 10 generates heat, This is because the blocking portion 23 is fixed to the ball 10. Therefore, the contact area between the blocking portion 23 and the ball 10, that is, the area of the spherical surface of the ball 10 that protrudes from the second opening 32 and contacts the tip concave spherical surface 23 a of the blocking portion 23 is as follows. It is necessary to set larger than the welded part area. Here, the welded portion area is an area where the tip end surface of the shaft member 11 is joined to the ball 10, specifically, a circular area in the welded portion indicated by reference numeral 70 in FIG. 11 corresponds to a cross-sectional area of 11. More precisely, it is the surface area of the spherical surface of the ball 10 at the part where the shaft member 11 is joined to the ball 10.

  At the stage after the casting of the holder 2 and before the shaft member 11 is welded to the ball 10, the main body portion 20 of the holder 2 moves outside the resin sliding contact member 3 due to the shrinkage of the holder 2 that proceeds after casting. Therefore, a large resistance acts on the rotation of the ball 10 relative to the resin sliding contact member 3 as it is. Further, since the tip concave spherical surface 23a formed in the closing portion 23 of the holder 2 by the casting is in close contact with the ball 10, the free rotation of the ball 10 is also prevented in this respect.

  However, when the shaft member 11 is electrically resistance-welded to the ball 10 after the holder 10 is cast, the ball 10 is heated by using the vicinity of the joint portion between the ball 10 and the shaft member 11 as a heat source. The heat is also transmitted to the resin sliding contact member 3 that is tightening. Since the ball 10 and the resin sliding contact member 3 have a difference in coefficient of thermal expansion and also have a difference in contraction speed at the time of cooling, the resin sliding contact member 3 once spread by heating is not at the time of cooling. It is not possible to completely return to the original shape at the contraction stage, and it is possible to loosen the resin sliding contact member 3 with respect to the ball 10.

  At this time, the ball 10 itself undergoes a slight thermal expansion at a lower temperature than normal temperature and pushes and spreads the resin sliding contact member 3. However, since the heat source is a joint portion between the ball 10 and the shaft member 11, the ball 10 10, the amount of expansion increases in the vicinity of the first opening 31, and the amount of expansion decreases in the vicinity of the second opening 32 away from the heat source than in the vicinity of the first opening 31. That is, the amount by which the resin sliding contact member 3 is expanded by the thermal expansion of the ball 10 is larger in the vicinity of the first opening 31 than in the vicinity of the second opening 32. As a result, in a state where the bonding of the ball 10 and the shaft member 11 is completed and the ball is cooled, the ball 10 is slightly displaced in the direction in which the ball 10 is lifted from the closing portion 23. Although the contact is made with the concave concave spherical surface 23a, the contact surface pressure between them is reduced.

  That is, in the ball joint of this embodiment, when the electric resistance welding of the shaft member 11 to the ball 10 is completed, the tightening force of the resin sliding contact member 3 to the ball 10 is reduced, and the ball 10 and the closing portion 23 are further reduced. The contact surface pressure with the tip concave spherical surface 23a is reduced, and the ball stud 1 completed by the welding can be moved lightly with respect to the holder 2.

  In particular, in the above-described embodiment, the inner diameter D2 of the second opening 32 of the resin sliding contact member 3 is smaller than the inner diameter D1 of the first opening 31, and the ball 10 is formed from the center of the closing portion 23. More spherical surfaces are in contact with the resin sliding contact member 3 on the side. For this reason, when the fastening force of the resin sliding contact member 3 is reduced by welding the shaft member 11 to the ball 10, the first opening 31 and the second opening 32 are formed to have the same inner diameter. In comparison with the ball 10, the degree of freedom in the direction in which the ball 10 floats from the closing portion 23 is likely to increase. Therefore, in the ball joint of this embodiment, the contact surface pressure between the metal sliding contact surface 23a of the closing portion 23 and the ball 10 can be further reduced, and the contact state between the ball 10 and the closing portion 23 is maintained. The stud 1 can be moved lightly with respect to the holder 2.

  Next, a gap is formed between the closed portion 23 of the holder 2 and the ball 10 of the ball stud 1, and the contact state between the tip concave spherical surface 23 a of the closed portion 23 and the ball 10 is eliminated. In this step, a gap forming load F2 is applied in the axial direction to the ball stud 1 completed by the above-described electric resistance welding, and the ball 10 is pressed against the tip concave spherical surface 23a of the closing portion 23. Specifically, as shown in FIG. 6, an annular pressure receiving jig 80 is disposed on the fixed portion 8, and the electrode mounting surface 24 provided on the closing portion 23 of the holder 2 is disposed on the pressure receiving jig 80. In this state, a gap forming load F2 is applied to the ball stud 1 in a direction in which the ball 10 is pressed against the closing portion 23 of the holder 2.

  Since the pressure receiving jig 80 is in contact with the periphery of the closing portion 23 of the holder 2 so as to surround the axis of the ball stud 1, when the gap forming load F <b> 2 is applied to the ball stud 1, the ball 10 is The closing part 23 of the holder 2 is pressed down so that the closing part 23 is plastically deformed. At this time, the ball 10 is slightly displaced in the holder 2 in accordance with the amount of plastic deformation of the closing portion 23, and between the main body portion 20 of the holder 2 and the ball 10 of the ball stud 1. The resin-sliding contact member 3 existing in the frame is elastically deformed by the gap forming load F2. Thereafter, when the gap forming load F2 is removed, the resin sliding contact member 3 that has been elastically deformed is restored to its original shape, and accordingly, the ball 10 is separated from the tip concave spherical surface 23a of the closing portion 23. Will be displaced. Thereby, a gap is formed between the ball 10 of the ball stud 1 and the closing portion 23 of the holder 2. The size of the gap depends on the size of the gap forming load F2.

  In this step, a gap is positively formed between the ball 10 of the ball stud 1 and the closing portion 23 of the holder 2 by applying the gap forming load F2 to the ball stud 1, but the ball 10 itself Is in contact with the resin sliding contact member 3 fixed to the main body 20 of the holder 2 without a gap, and the contact state between the resin sliding contact member 3 and the ball 10 does not change before and after this step. Therefore, even if a gap is positively formed between the ball 10 of the ball stud 1 and the closing portion 23 of the holder 2, the ball 10 is in sliding contact with the resin sliding contact member 3 without a gap. Thus, there is no problem that the ball stud 1 rattles with respect to the holder 2.

  Further, in the process of forming a gap between the closing portion 23 of the holder 2 and the ball 10 of the ball stud 1, the gap may be formed through two steps. For example, as a step before using the above-described annular pressure receiving jig 80 (see FIG. 6), as shown in FIG. 7, a disk-shaped pressure receiving force is applied to the electrode mounting surface 24 formed outside the closing portion 23. The jig 81 is brought into contact, and in this state, the gap forming load F2 is applied to the ball stud 1, and then the gap forming load F2 is applied again using the annular pressure receiving jig 80. After such a two-step process, in the process using the disc-shaped pressure receiving jig 81, the closing portion 23 is crushed between the ball 10 and the pressure receiving jig 81 and plastically deformed, In the process using the annular pressure receiving jig 80, the closing portion 23 is pushed down. Thereby, compared with the case where only the annular pressure receiving jig 80 is used, a larger gap can be formed between the closing portion 23 of the holder 2 and the ball 10 of the ball stud 1.

  The shape of the pressure receiving jigs 80 and 81 described above is merely an example, and when the gap forming load F2 is applied to the ball stud 1, the closing portion 23 of the holder 2 is pressed by the ball 10 to be plastic. If it can be deformed, its shape can be selected as appropriate.

  Then, according to such a method for manufacturing a ball joint, when the shaft member 11 is electrically resistance-welded to the ball 10, a power supply opening is formed with respect to the holder 2 covering the periphery of the ball 10. No need for a cap for closing the power supply opening after completion of the welding of the ball stud 1, it is possible to realize a reduction in the number of parts and simplification of the production process, and the production cost. Can be reduced.

  After the clearance forming load F2 is removed, the concave spherical surface 23a of the closing portion 23 and the ball 10 of the ball stud 1 are not in contact with each other, and the ball 10 is in resin sliding contact with the resin sliding contact member 3. Only the surface 30 is in contact. Thereby, the ball 10 of the ball stud 1 does not rub against the metal holder 2 formed by casting during the swinging motion of the ball stud 1, and the ball stud 1 rattles against the holder 2. In this way, smooth operation of the ball stud 1 can be ensured over a long period of time.

  DESCRIPTION OF SYMBOLS 1 ... Ball stud, 2 ... Holder, 3 ... Resin slidable contact member, 10 ... Ball, 11 ... Shaft member, 20 ... Main-body part, 23 ... Closure part, 23a ... Concave spherical surface of a tip, 31 ... First opening part, 32 ... Second opening

Claims (4)

A resin sliding contact member having a sliding contact surface with a ball of the ball stud to cover the maximum diameter portion of the ball and having a first opening and a second opening in which the spherical surface of the ball is exposed in opposite directions. Molding process;
The ball and the spherical surface of the ball protruding from the second opening of the resin sliding contact member by casting the ball and the resin sliding contact member placed on the ball as a core Forming a holder that has a closing portion that covers and touches the ball, and that is not in contact with the spherical surface of the ball exposed from the first opening of the resin sliding contact member;
The shaft member is abutted against the ball exposed from the first opening of the resin sliding contact member, and the electrode is brought into contact with the shaft member, while the electrode is brought into contact with the closing portion of the holder in contact with the ball. And joining the shaft member by electric resistance welding to form the ball stud;
A method of manufacturing a ball joint, comprising: applying a gap forming load in the axial direction to the ball stud to make the ball and the concave concave spherical surface of the closed portion non-contact. The ball joint manufacturing method according to claim 1, wherein the resin sliding contact member covers a maximum diameter portion of the ball, and an inner diameter of the second opening portion is set smaller than an inner diameter of the first opening portion. Method. The resin sliding contact member has the second opening so that a spherical surface area of the ball that contacts the closing portion of the holder through the second opening is larger than a welded area of the tip surface of the shaft member to the ball. The ball joint manufacturing method according to claim 2, wherein an inner diameter of the portion is set. 4. The ball joint manufacturing method according to claim 3, wherein when the gap forming load is applied to the ball stud, an annular pressure receiving jig is brought into contact with the closed portion of the holder.

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