JP5316837B2 - Ball joint manufacturing method - Google Patents

Description

  The present invention relates to a ball joint manufacturing method.

  In general, a ball joint has a spherical head provided at one end of a ball stud and a resin sheet covering the spherical head. One end of the housing is sealed and the other end is used as an inlet for the resin sheet and the spherical head. It is configured to be accommodated in a cylindrical accommodation chamber. Further, the resin sheet is generally formed in a cup shape in which a bottom portion facing the bottom of the storage chamber is provided at one end of the cylindrical peripheral wall portion, and the opposite side is opened.

For example, an inner ball joint or the like of a steering device for an automobile prevents the ball head from coming off by caulking the entrance and making it smaller in diameter than the other part in a state where the resin sheet and the ball head are accommodated in the accommodation chamber. It is configured by pressurizing a resin sheet.
The resin sheet is loaded into the ball joint and pressurized, and the first pressure receiving pressure is received when a force is applied to the bottom side of the resin sheet in the direction of pressing the ball head of the ball stud against the bottom of the storage chamber. And a second pressure receiving region that receives the force when a force is exerted in a direction in which the ball head is pulled out of the storage chamber.

  Comparing these two areas, the second pressure receiving area is provided around the opening through which the rod extending so as to protrude from the ball head of the ball stud is inserted, and since the pressure receiving area is smaller than the first pressure receiving area, the load load is reduced. In this second pressure receiving region, there is a problem that so-called sag, in which the thickness of the resin sheet decreases locally with time, and abnormal noise due to backlash are likely to occur.

If the resin sheet is made of a relatively hard resin, settling can be prevented. In this case, however, the elasticity of the resin sheet will be reduced, so that variations in the processing dimensions when caulking the entrance of the storage chamber will cause elastic deformation of the resin sheet. Cannot be sufficiently absorbed, and the variation in the pressure applied to the resin sheet becomes large. For example, the steering device cannot stabilize the torque. Therefore, it has been proposed that the resin sheet has a split structure made up of a first sheet including the first pressure-receiving region and a resin relatively harder than the first sheet, and including a second sheet including the second pressure-receiving region. (For example, refer to Patent Document 1).
Japanese Patent Publication No. 6-8645

  When the resin sheet is divided into two parts, the variation in processing dimensions when caulking the inlet of the storage chamber is prevented while the settling of the second pressure receiving region is prevented by the relatively hard second sheet. The torque can be stabilized to some extent by absorbing the elastic deformation of the sheet and reducing the variation in the pressurization. However, the effect is not yet sufficient, and there is a problem that the number of parts and the number of assembly steps increase when the split structure is used.

  The present invention has been made under such a background, and without increasing the number of parts and the number of assembly steps, the generation of abnormal noise is prevented over a long period of time, and the variation in pressurization is small. It is an object of the present invention to provide a manufacturing method for manufacturing a ball joint that can stabilize torque when used in a steering device.

In order to achieve the above object, the present invention comprises a ball stud (18) having a ball head (23) at one end and a thermosetting resin that preliminarily covers the ball head and is preliminarily cured. The resin sheet (17) is accommodated in the accommodation chamber of the housing (16) having the accommodation chamber (19) for accommodating the resin sheet and the ball head, and the entrance of the accommodation chamber is crimped to have a small diameter. The resin sheet is heated to a temperature higher than the heat deformation temperature of the resin to cause heat deformation so that the resin can conform to the surface of the ball head and the inner peripheral surface of the storage chamber, and the resin is fully cured. A method for manufacturing a ball joint (12) is provided (claim 1). In addition, alphanumeric characters in parentheses represent corresponding components in the embodiments described later.

According to the present invention, the entire resin sheet including the second pressure receiving region on the opening side of the cup can be formed by a hard cured product of a thermosetting resin . For this reason, it is possible to satisfactorily suppress the occurrence of settling in the second pressure receiving region or the entire wear and prevent the generation of abnormal noise due to looseness over a long period of time.
Further, by heating after caulking the entrance of the accommodation chamber, the resin sheet made of a thermosetting resin in a temporarily cured state that can be thermally deformed before the main curing is thermally deformed, and the surface of the ball head and the accommodation chamber It can be made to fit well with the inner peripheral surface and the like. Therefore, despite the fact that the thermosetting resin is fully cured together with the thermal deformation by the heating and the entire resin sheet is formed as a one-piece with the hard cured product as described above, Compared to the structure, the variation in processing dimensions when caulking the entrance of the storage chamber to a small diameter can be absorbed well by the thermal deformation to reduce the pressure variation. For example, the torque of the steering device can be reduced more than ever. Can also be stabilized.

According to the present invention, since the resin sheet is formed in one piece, it is possible to prevent an increase in the number of parts and the number of assembly steps .

The resin sheet is poured by pouring molten resin into the gap where the housing and the ball head are positioned and cooling to solidify, or by pouring a thermosetting resin such as liquid or powder and heating and curing. Can also be considered. However, in this case, it is not possible to form an optimally shaped resin sheet having a lubricating oil groove, a through hole, or the like at the bottom.
In order to form an optimally shaped resin sheet with small variations in pressurization by satisfactorily absorbing variations in processing dimensions when caulking the entrance of the storage chamber, in addition to having the oil grooves and through holes in predetermined positions The production method of the present invention is optimal.

Embodiments of the present invention will be specifically described below with reference to the drawings.
FIG. 1 is a schematic diagram illustrating a schematic configuration of a steering apparatus 1 including a ball joint according to an embodiment manufactured by the manufacturing method of the present invention. The steering device 1 includes a steering wheel 2 as a steering member and a rack and pinion mechanism 3 as a turning mechanism for turning steered wheels (not shown).

The steering wheel 2 is connected to the rack and pinion mechanism 3 via a steering shaft 4 and an intermediate shaft 5. The rotation of the steering wheel 2 is transmitted to the rack and pinion mechanism 3 via the steering shaft 4 and the intermediate shaft 5.
The rack and pinion mechanism 3 includes a pinion shaft 6 and a rack shaft 7. The pinion shaft 6 includes a shaft portion 8 connected to the intermediate shaft 5 and a pinion 9 connected to the tip of the shaft portion 8. The rotation of the steering wheel 2 is transmitted to the pinion shaft 6 via the steering shaft 4 and the intermediate shaft 5.

The rack shaft 7 extends along the left-right direction of the vehicle. A rack 10 is formed on the rack shaft 7. The pinion 9 and the rack 10 are meshed with each other. The rotation of the pinion shaft 6 is converted into an axial movement of the rack shaft 7 by the rack 10 and the pinion 9.
The rack shaft 7 is inserted into a cylindrical housing 11. Both end portions of the rack shaft 7 protrude from the housing 11. One end of a tie rod 14 is connected to each end of the rack shaft 7 via an inner ball joint 12. An outer ball joint 13 is provided at the other end of the tie rod 14 (so-called tie rod end). Although not shown, the steered wheels are connected to the outer ball joint 13 via a knuckle arm.

  A cylindrical rack boot 15 is disposed at each end of the housing 11. One end of each rack boot 15 is fitted around the end of the housing 11 and is fixed to the end. Further, the other end of each rack boot 15 is externally fitted to the tie rod 14 and is fixed to the tie rod 14. The end of the housing 11 and the inner ball joint 12 are covered with a corresponding rack boot 15. The rack boot 15 prevents foreign matters such as water and dust from entering the housing 11 and the inner ball joint 12.

  In the steering operation (rotation operation), as described above, the rotation of the steering wheel 2 is transmitted to the pinion shaft 6 by the steering shaft 4 and the intermediate shaft 5, and the rotation of the pinion 9 is moved in the axial direction of the rack shaft 7 through the rack 10. Converted. The axial movement of the rack shaft 7 at that time is transmitted to the tie rod 14 via the inner ball joint 12, and the movement of the tie rod 14 is further transmitted to the knuckle arm via the outer ball joint 13.

FIG. 2 is a cross-sectional view of a part of the steering device 1 including the inner ball joint 12 and the outer ball joint 13.
The inner ball joint 12 includes a housing 16 connected to the end of the rack shaft 7, and a resin sheet 17 and a ball stud 18 held by the housing 16. The housing 16 includes a storage chamber 19 that stores the resin sheet 17 and the ball stud 18, and a connecting portion 20 that is connected to the end of the rack shaft 7. The storage chamber 19 has a cylindrical shape with a sealed bottom and has an inlet. The resin sheet 17 has a cup shape and includes a peripheral wall portion 21 and a bottom portion 22. The resin sheet 17 is disposed so that the bottom portion 22 faces the bottom of the storage chamber 19.

  The ball stud 18 is integrally formed with a spherical head 23 having a spherical outer surface and a rod 24 extending so as to protrude from the spherical head 23. The spherical head 23 is covered with the resin sheet 17, and the rod 24 protrudes from the storage chamber 19. A part of the tie rod 14 is constituted by a ball stud 18. That is, the tie rod 14 includes a ball stud 18 and a connecting shaft 25 connected to the rod 24 of the ball stud 18.

The entrance of the storage chamber 19 is caulked after receiving the ball head 23 covered with the resin sheet 17 to have a small diameter so that the ball head 23 and the resin sheet 17 are prevented from coming off.
A male screw portion 26 is formed at the tip portion (right end portion in FIG. 2) of the rod 24. The male screw portion 26 is screwed into a female screw hole 27 formed in the connecting shaft 25. The male screw portion 26 is screwed into the female screw hole 27, whereby the connecting shaft 25 is coaxially connected to the ball stud 18.

  A lock nut 28 is screwed into the male screw portion 26. The ball stud 18 and the connecting shaft 25 are fixed to each other by a lock nut 28. Further, the screwing amount of the male screw portion 26 with respect to the female screw hole 27 is adjusted by a lock nut 28. The toe angle of the steered wheel can be adjusted by adjusting the screwing amount of the male screw portion 26 into the female screw hole 27.

  The ball head 23 is held so as to be wrapped in the storage chamber 19 via the resin sheet 17. The inner peripheral surface of the resin sheet 17 has a shape along the outer surface of the ball head 23. The ball head 23 is slidable with respect to the resin sheet 17. A lubricant such as grease is filled between the resin sheet 17 and the ball head 23. The ball stud 18 can swing with respect to the housing 16 with the ball head 23 as a fulcrum. Therefore, the movement of the rack shaft 7 (see FIG. 1) in the axial direction is not transmitted linearly to the tie rod 14 in the axial direction, but is transmitted in the angular direction where the inner ball joint 12 swings.

  On the other hand, the outer ball joint 13 includes a housing 29 and a resin sheet 30 and a ball stud 31 held by the housing 29. The housing 29 includes a cylindrical member 32 in which the resin sheet 30 is disposed, and a closing plate 33 fixed to the one end so as to close one end (the lower end in FIG. 2) of the cylindrical member 32. The cylindrical member 32 is integrally formed at the distal end portion of the connecting shaft 25, for example.

  The resin sheet 30 includes a cup-shaped first sheet 34 and a plate-shaped second sheet 35. The first sheet 34 is integrally provided with a peripheral wall portion 36 and a bottom portion 37. The first sheet 34 is disposed such that the peripheral wall portion 36 is along the inner peripheral surface of the cylindrical member 32. The second sheet 35 is interposed between the bottom 37 of the first sheet 34 and the closing plate 33. The resin sheet 30 is held between an annular flange 38 projecting inward from the other end (upper end in FIG. 2) of the cylindrical member 32 and the closing plate 33.

  The ball stud 31 is integrally formed with a spherical head 39 having a spherical outer surface and a rod 40 protruding upward from the spherical head 39. The spherical head 39 is covered with the first sheet 34, and the rod 40 protrudes from the cylindrical member 32. The spherical head 39 is held by the housing 29 via the first sheet 34. That is, the ball stud 31 is held by the housing 29 via the first sheet 34.

  The inner peripheral surface of the first sheet 34 is shaped along the outer surface of the ball head 39. The spherical head 39 is slidable with respect to the resin sheet 30. A lubricant such as grease is filled between the first sheet 34 and the ball head 39. The ball stud 31 can swing with respect to the housing 29 with the ball head 39 as a fulcrum. Further, the ball stud 31 is rotatable around the central axis of the rod 40. The outer ball joint 13 transmits the movement of the tie rod 14 to the knuckle arm in the swinging angular direction.

  A cylindrical cover 41 is attached to the housing 29 and the ball stud 31. One end of the cover 41 is fitted around the end of the cylindrical member 32 and is fixed to the end. The other end of the cover 41 is externally fitted to the rod 40 and is fixed to the rod 40. An end of the cylindrical member 32 and a part of the rod 40 are covered with a cover 41. The cover 41 prevents foreign matters such as water and dust from entering the outer ball joint 13.

Next, a specific configuration of the ball joint according to this embodiment will be described by taking the inner ball joint 12 as an example.
FIG. 3 is a partial cross-sectional view showing a schematic configuration of the inner ball joint 12 according to the embodiment manufactured by the manufacturing method of the present invention. FIG. 4 is a partial cross-sectional view showing a state in the middle of manufacturing the inner ball joint 12 by the manufacturing method of the present invention.

With reference to FIG. 3, the inner ball joint 12 includes a ball stud 18, a housing 16, and a resin sheet 17. The ball stud 18 is an integrally molded product using a single member made of metal such as steel, and includes a ball head 23 and a rod 24. The center C of the spherical head 23 is disposed on the central axis L1 of the rod 24.
The housing 16 accommodates the ball head 23 and supports the ball stud 18 via the resin sheet 17 so as to be swingable with the ball head 23 as a fulcrum. The housing 16 is an integrally molded product using a single member made of metal such as steel, and includes a storage chamber 19 and a connecting portion 20. The storage chamber 19 includes a cylindrical peripheral wall 42 that surrounds the spherical head 23, and a bottom wall 43 that is connected to one end of the peripheral wall 42 in the axial direction and seals one end of the cylinder to form the bottom.

  The bottom of the storage chamber 19 has a tapered shape in which the opening diameter increases from one side surface (inner bottom surface) 45 of the bottom wall 43 to the other end (front end) side of the peripheral wall 42 from the inner bottom surface 45 side. And the tapered surface 46 is connected to the inner bottom surface 45 and the inner peripheral surface 44 of the peripheral wall 42, and the inner head 45 and the tapered surface 46 and the inner peripheral surface 44 accommodate the ball head 23 and the resin sheet 17. An accommodating space 47 is defined. The inner peripheral surface 44 and the tapered surface 46 are opposed to the surface of the spherical head 23. The connecting portion 20 is formed integrally with the bottom wall 43.

  An opening 48 is formed at the other end (tip) of the peripheral wall 42, and the spherical head 23 is accommodated in the accommodation space 47 through the opening 48. The rod 24 is inserted through the opening 48. The peripheral portion 49 of the opening 48 of the peripheral wall 42 has a smaller diameter than the other portions of the peripheral wall 42, and the ball head 23 and the resin sheet 17 are prevented from coming out of the storage chamber 19. 3 and 4, this peripheral portion 49 has a small diameter by caulking (plastically deforming) the other end (tip) of the peripheral wall 42 on the side of the opening 48 of the peripheral wall 42 having a substantially constant outer diameter. It is said that.

Referring to FIG. 4, the resin sheet 17 is provided with a bottom portion 22 opposite to the bottom of the storage chamber 19 at one end of the peripheral wall portion 21 whose outer periphery is formed in a cylindrical shape along the inner peripheral surface 44 of the storage chamber 19. One end of the other end is formed in a cup shape having an opening 50 through which the rod 24 is inserted. The bottom portion 22 is formed in a tapered shape along the tapered surface 46 in the bottom of the storage chamber 19.
A through hole 51 is formed at the center of the bottom 22. The through hole 51 is formed concentrically with the central axis L <b> 2 of the resin sheet 17. By providing the through-hole 51, when a force acts on the resin sheet 17 from the ball head 23, the deformation can be promoted to reduce the impact. The through hole 51 is filled with a lubricant such as grease.

3 and 4, the resin sheet 17 and the ball head 23 are accommodated in the accommodation space 47 of the accommodation chamber 19, and then the other end (tip) of the peripheral wall 42 on the opening 48 side is caulked, and the peripheral portion By making 49 a small diameter, the cup-shaped resin sheet 17 is elastically deformed and pressurized so as to fill the gap between the storage chamber 19 and the ball head 23.
Then, the resin sheet 17 is heated to the thermal deformation temperature of the thermosetting resin to form a resin sheet 17 (deflection temperature under load) or causes thermal deformation, the thermosetting resin Ru is cured.

It is elastically deformed further inner peripheral surface 52 of the resin sheet 17, which is thermally deformed Rutotomoni cured by heating is formed in a shape along the surface of the ball head portion 23, to support the spherical head portion 23 slidably . The outer peripheral surface 53 of the resin sheet 17 is formed in a shape along the inner peripheral surface 44 and the tapered surface 46 of the storage chamber 19, and is supported by the inner peripheral surface 44 and the tapered surface 46.
In a state where the central axis L1 of the rod 24 and the central axis L2 of the resin sheet 17 coincide with each other (the state shown in FIG. 3), the resin sheet 17 passes through the center C of the spherical head 23 and is orthogonal to the central axis L1. A region located farther from the opening 48 of the storage chamber 19 than the plane A is a first pressure receiving region 54.

When the force F1 is applied to the first pressure receiving region 54 in the direction in which the ball head 23 is pressed against the bottom of the storage chamber 19 via the rod 24 (for example, one U1 in the direction along the central axis L2 of the resin sheet 17). This is the region that receives this force F1.
When the central axes L1 and L2 coincide with each other, a region of the resin sheet 17 that is located closer to the opening 48 of the storage chamber 19 than the plane A is defined as a second pressure receiving region 55. Yes.

When the force F2 is applied to the second pressure receiving region 55 in the direction in which the ball head 23 is removed from the opening 48 via the rod 24 (for example, the other U2 in the direction along the central axis L2 of the resin sheet 17). This is the region that receives the force F2.
Since the second pressure receiving region 55 is provided around the opening 50 through which the rod 24 extending so as to protrude from the ball head 23 of the ball stud 18 is inserted, the pressure receiving area is smaller than that of the first pressure receiving region 54. ing. Therefore, the load load tends to increase.

However, by forming the entire resin sheet 17 including the second pressure receiving region 55 with a hard cured product of a thermosetting resin , settling occurs in the second pressure receiving region 55 or the entire resin sheet 17 is worn. The occurrence of abnormal noise due to looseness can be prevented over a long period of time.
In addition, the resin sheet 17 can be thermally deformed by heating after the entrance of the storage chamber 19 is caulked so that the surface of the ball head 23 and the inner peripheral surface 44 and the tapered surface 46 of the storage chamber 19 can be satisfactorily adjusted. . Therefore, despite the fact that the entire resin sheet 17 is formed in one piece with the hard cured material of the thermosetting resin as described above, the entrance of the storage chamber 19 is made more than the conventional one with the split structure. The variation in processing dimensions when caulking to a small diameter can be satisfactorily absorbed by the thermal deformation to reduce the pressure variation, and for example, the torque of the steering device can be stabilized more than before.

Further, according to the present invention, since the resin sheet 17 is formed in one piece, it is possible to prevent an increase in the number of parts and the number of assembly steps .

By previously temporarily cured thermosetting resin to form the or resin sheet 17 to form a resin sheet of optimum shape having a bottom such as oil grooves and through holes for lubrication or the like.

For example, by molding a thermosetting resin using a high-temperature mold, immediately demolding and cooling, a temporarily cured resin sheet 17 in which only the thermosetting resin near the surface is cured can be obtained.
The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the claims. Moreover, the ball joint manufactured by the manufacturing method of the present invention can be used for applications other than the application of connecting the rack shaft and the tie rod.

It is a mimetic diagram showing a schematic structure of steering device 1 provided with a ball joint concerning one embodiment manufactured by a manufacturing method of the present invention. It is a sectional view of a part of a steering device including an inner ball joint and an outer ball joint. It is a partial sectional view showing a schematic structure of inner ball joint 12 concerning one embodiment manufactured by a manufacturing method of the present invention. It is a partial cross section figure which shows the state in the middle of manufacturing the inner ball joint 12 with the manufacturing method of this invention.

Explanation of symbols

  12: ball joint (inner ball joint), 16: housing, 17: resin sheet, 18: ball stud, 19: storage chamber, 23: ball head.

Claims (1)

A ball stud having a sphere head at one end, and a resin sheet formed of a thermosetting resin preliminarily cured and covering the sphere head in a one-piece form, containing the resin sheet and the sphere head The housing having a chamber is housed in the housing chamber, and the inlet of the housing chamber is squeezed to a small diameter, and then heated to a temperature higher than the heat deformation temperature of the resin forming the resin sheet to be thermally deformed. A ball joint manufacturing method , wherein the resin is fully cured while conforming to the surface and the inner peripheral surface of the storage chamber .

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