Ball joint socket, ball joint, and method for manufacturing a ball joint socket

Abstract

To provide a socket of a ball joint which can securely hold a bearing seat, a ball joint including the socket, and a method of manufacturing a socket of a ball joint.SOLUTION: A socket 4 includes a cylindrically formed metallic body part 20 holding a bearing seat, at least one concave part 37 formed on an inner peripheral surface 25 of the body part 20, and a convex part 38 formed in an edge part of the concave part 37 and rising from the inner peripheral surface 25.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a socket of a cylindrical ball joint that holds a bearing sheet, a ball joint provided with the same, and a method for manufacturing the socket of the ball joint.

Background Art

[0002] Conventionally, as a ball joint, a cylindrical ball sheet that rotatably holds the ball portion of a ball stud is housed in a cylindrical socket (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0007] According to the present invention, the bearing seat can be firmly held in the socket. [Brief explanation of the drawing]

[0008] [Figure 1] This shows a socket of a ball joint according to one embodiment of the present invention, where (a) is a cross-sectional view showing the main body portion before bending of the bent portion, (b) is a plan view of (a), and (c) is an enlarged cross-sectional view showing a part of the inner circumferential surface of the main body portion. [Figure 2] (a) is a front view showing an example of the inner surface of the socket, and (b) is a front view showing another example of the inner surface of the socket. [Figure 3] This is a cross-sectional view showing a ball joint equipped with the same socket. [Figure 4] This is a front view showing an example of a manufacturing apparatus for the sockets mentioned above. [Modes for carrying out the invention]

[0009] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

[0010] In Figure 3, 1 represents a ball joint. Ball joint 1 is an automotive ball joint used, for example, in the steering system of an automobile. In this embodiment, ball joint 1 will be explained using an example of a ball joint (inner ball joint (IBJ)) used in the rack end of a steering system to transmit the steering amount transmitted from the steering wheel side to the tire side.

[0011] The ball joint 1 comprises a ball stud 2, which is the ball-side member; a bearing seat 3, which is the sliding member (ball seat); and a socket 4, which is the receiving member. Although not shown, the ball joint 1 may also be equipped with a dust cover.

[0012] The ball stud 2 has a spherical ball portion 10 at one end, and a shaft-shaped stud portion 11 is connected from the ball portion 10 to the other end. The ball stud 2 is made of steel or the like. Hereafter, the ball stud 2 will be described based on its neutral position.

[0013] The ball portion 10 is held in place by the bearing seat 3 so that a portion of its outer surface can slide or rotate.

[0014] The stud portion 11 is the part that is connected to an external member to which a load is applied. In this embodiment, the stud portion 11 is the part that is connected to the tire side (tie rod end). The stud portion 11 may be molded integrally with the ball portion 10, or it may be molded separately from the ball portion 10 and then integrated with the ball portion 10 by welding or the like.

[0015] The bearing seat 3 is formed in a cylindrical shape from synthetic resin. The bearing seat 3 integrally comprises a seat body portion 13, which is the cylindrical retaining member body portion, and a load receiving portion 14 connected to the end of the seat body portion 13. The bearing seat 3 has at least one seat opening 15 at one end, which is the opening of one retaining member. The seat opening 15 is located at one end of the seat body portion 13 or the bearing seat 3. In this embodiment, the bearing seat 3 also has another seat opening 16 at the other end, which is the opening of the other retaining member. The other seat opening 16 is formed to penetrate the load receiving portion 14. The inner circumferential surface of the bearing seat 3 is the sliding contact surface with the ball portion 10. Grooves, recesses, protrusions, etc. may be formed on the inner circumferential surface of the bearing seat 3 as needed. The bearing seat 3 is formed from a synthetic resin or the like, which has excellent wear resistance and a high modulus of elasticity. In other words, the bearing seat 3 is made from a material that is softer than the socket 4. Furthermore, the bearing seat 3 is not limited to being formed as a single, integral piece; it may also be formed by combining multiple seat members, such as a two-piece type.

[0016] The seat body portion 13 is pre-formed into a straight cylindrical shape having a constant or substantially constant inner diameter. With the bearing seat 3 housed inside the socket 4, it deforms in accordance with the deformation of the socket 4, so as to gradually reduce in diameter along the outer circumferential surface of the ball portion 10 toward one end that is away from the load-receiving portion 14. With the seat body portion 13 housed in the socket 4, the seat body portion 13 is a bent portion of the retaining member, called a seat bent portion 18, where the bend point is at a predetermined axial position, in this embodiment, at a position that intersects with a plane including the equator position E of the ball portion 10, and the portion extending from the equator position E to one end that is the peripheral edge of one of the seat openings 15 is bent so as to gradually reduce in diameter toward one end.

[0017] The load-receiving portion 14 is formed by gradually decreasing in diameter in the direction away from the seat body portion 13, that is, toward the other end of the bearing seat 3. The outer circumferential surface of the load-receiving portion 14 is formed in a truncated cone shape.

[0018] One sheet opening 15 is preformed to have a diameter dimension larger than that of the ball portion 10, and in a state where the bearing sheet 3 is accommodated in the socket 4, the diameter is reduced to a dimension smaller than that of the ball portion 10 by the sheet bending portion 18.

[0019] The socket 4, also called a housing or the like, is made of metal formed by forging, casting, or the like. In the present embodiment, the socket 4 has a bottomed cylindrical main body portion 20. That is, the main body portion 20 integrally has a side wall portion 22 that is a cylindrical receiving-side member main body and a closing portion 23 that closes the end portion of the side wall portion 22. Inside the main body portion 20, an inner chamber 24 for accommodating the bearing sheet 3 is formed by the side wall portion 22 and the closing portion 23, and this inner chamber 24 is surrounded by the inner peripheral surface 25 of the socket 4. Further, an opening 26 that communicates the inner chamber 24 with the outside of the socket 4 is formed at one end portion that is the end portion on the opposite side of the closing portion 23 in the axial direction of the main body portion 20, that is, the tip end portion side of the side wall portion 22. Note that a cover fixing groove as a cover attachment portion for fixing a dust cover may be formed in the socket 4.

[0020] As shown in FIG. 1(a), the side wall portion 22 is preformed in a straight cylindrical shape having a constant or substantially constant inner diameter dimension, and as shown in FIG. 3, in a state where the bearing sheet 3 is accommodated inside the socket 4 or the main body portion 20 (inner chamber 24), a position intersecting a plane including the equatorial position E of the ball portion 10 at a predetermined position in the axial direction, in the present embodiment, is used as a bending point, and a portion extending from this bending point to one end portion that is the peripheral edge portion of the opening 26 is bent so as to gradually reduce the diameter toward the one end portion to form a bending portion 28. That is, the inner chamber 24 is formed to be narrower at the position of the bending portion 28. That is, at the position of the bending portion 28, the inner peripheral surface 25 of the socket 4 gradually reduces the diameter toward the one end portion. Due to this bending portion 28, the bearing sheet 3 holding the ball portion 10 is prevented from coming off the socket 4. As an example, the bending portion 28 is a caulking portion formed by caulking and deforming one end portion side of the side wall portion 22 toward the central axis side.

[0021] Further, the bent portion 28 is located at one end of the side wall portion 22 or the socket 4 and is not formed at the other end. That is, the other end side of the side wall portion 22 is a straight cylindrical non-bent portion 30. The non-bent portion 30 forms a portion extending from a position intersecting the plane including the equator position E of the ball portion 10 to the closing portion 23. At the position of the non-bent portion 30, the diameter dimension of the inner peripheral surface 25 of the socket 4 is constant or substantially constant.

[0022] The closing portion 23 is formed continuously with the other end of the side wall portion 22. The closing portion 23 is formed in a direction intersecting the axial direction of the side wall portion 22 and closes the other end of the side wall portion 22. The closing portion 23 is axially opposed to the ball portion 10 via the bearing sheet 3 and is the portion that receives the largest load from the ball stud 2 side in the socket 4. Further, an external connection portion 32 connected to an external connected portion such as a handle side (rack shaft) may be formed coaxially with the main body portion 20 outside the closing portion 23. In the present embodiment, the connection portion 32 is formed, for example, in a male screw shape. The connection portion 32 is not an essential configuration.

[0023] The inner chamber 24 is formed so as to gradually decrease in diameter toward the other end of the socket 4 at a position corresponding to the closing portion 23.

[0024] The inner peripheral surface 25 is a portion that contacts or is in close proximity to the outer peripheral surface of the bearing sheet 3. At least a part of the inner peripheral surface 25 is formed with a rough surface processing portion 35. The rough surface processing portion 35 is formed by processing the inner peripheral surface 25, contacts the outer peripheral surface of the bearing sheet 3, and is a portion that bites into the outer peripheral surface of the bearing sheet 3. The holding strength of the bearing sheet 3 with respect to the socket 4 or the main body portion 20 is set by the rough surface processing portion 35.

[0025] In the present embodiment, as shown in FIG. 1(c), the rough surface processing portion 35 has at least one recess 37 and a convex portion 38 formed at the outer edge portion of the recess 37. In the illustrated example, a plurality of recesses 37 are formed, and convex portions 38 are formed at the outer edge portions of each of these recesses 37.

[0026] The recesses 37 are formed as hemispherical depressions (dimples). The diameter of the recesses 37 is set according to the beam shape (beam diameter) of the laser L that forms the recesses 37. In this embodiment, the recesses 37 are formed in a regular or irregular arrangement at a predetermined pitch. As an example of a regular arrangement, as shown in Figures 2(a) and 2(b), the recesses 37 are arranged at equal or approximately equal intervals at a predetermined pitch P1 in the circumferential direction of the inner circumferential surface 25, and also at equal or approximately equal intervals at a predetermined pitch P2 in the axial direction of the inner circumferential surface 25. The pitches P1 and P2 of the recesses 37 are set according to the durability performance required of the ball joint 1 (Figure 3) and / or the size of the ball joint 1 (Figure 3). The circumferential pitch P1 and the axial pitch P2 of the inner circumferential surface 25 may be the same or different. The arrangement of the recesses 37 may be a planar square grid, as shown in Figure 2(a), or a planar oblique grid (staggered pattern), as shown in Figure 2(b).

[0027] The protrusion 38 shown in Figure 1(c) is formed along the outer edge of the recess 37. The protrusion 38 is formed when a portion of the material of the inner circumferential surface 25, which melted during the formation of the recess 37, is pushed out from the recess 37 and solidified. Preferably, the protrusion 38 is an annular shape that extends along the periphery of the recess 37, but it may be interrupted in part and have an arc shape or the like. The protrusion 38 protrudes with a smaller amount of projection than the depth of the recess 37. In cross-sectional shape, the protrusion 38 is mountain-shaped, protruding on both sides of the recess 37, and each mountain portion has a smaller width dimension than the recess 37, and in the illustrated example, it is formed with a width dimension of less than half that of the recess 37.

[0028] The position and range in which the roughened surface portion 35 shown in Figures 1(a) and 3 is formed are set according to the durability performance required for the ball joint 1. In this embodiment, the roughened surface portion 35 is the entire portion of the inner circumferential surface 25 of the main body portion 20 of the socket 4 that extends to one end. For example, the roughened surface portion 35 is a band-shaped region of the inner circumferential surface 25 extending from the point where the side wall portion 22 intersects with the plane containing the equator position E of the ball portion 10, i.e., the bending point of the bent portion 28, to the end where the opening 26 is located. In other words, the roughened surface portion 35 is the region on the inner circumferential surface 25 of the main body portion 20 of the socket 4 that corresponds to the bent portion 28. That is, the roughened surface portion 35 is the inner circumferential surface of the bent portion 28. Therefore, recesses 37 and protrusions 38 are formed around the entire circumference of the inner circumferential surface of the bent portion 28. The roughened surface portion 35 is such that the protrusions 38 bite into the outer circumferential surface of the seat bent portion 18 of the bearing seat 3. In Figure 3, the roughened surface area 35 is shown with its irregularities emphasized and its shape schematically illustrated for clarity.

[0029] On the inner circumferential surface 25, the portion other than the roughened portion 35 is a non-roughened portion 40 with a lower surface roughness than the roughened portion 35. In other words, if the entire inner circumferential surface 25 is roughened, the non-roughened portion 40 is not formed on the inner circumferential surface 25. In this embodiment, the non-roughened portion 40 is the region on the inner circumferential surface 25 of the main body portion 20 of the socket 4 that corresponds to the non-bent portion 30 or the closed portion 23. That is, the non-roughened portion 40 is the region of the inner circumferential surface 25 extending from the point where the side wall portion 22 intersects with the plane containing the equator position E of the ball portion 10, i.e., the bending point of the bending portion 28, to the closed portion 23 on the opposite side of the opening 26.

[0030] The opening 26 is the portion whose periphery is surrounded by the bent portion 28. The opening 26 is formed in a circular shape. The opening 26 is the portion with the smallest inner diameter inside the side wall portion 22. The opening 26 is initially formed with an inner diameter larger than the outer diameter of the ball portion 10 and the bearing seat 3, and when the bearing seat 3 is housed inside the socket 4, it is surrounded by the bent portion 28 so that its inner diameter becomes smaller than the outer diameter of the ball portion 10 and the bearing seat 3. In addition, an expanding portion 42 may be formed in a series in the opening 26. The expanding portion 42 is formed in a slope that gradually expands in diameter from the opening 26 toward one end of the socket 4. The expanding portion 42 is for avoiding interference between the stud portion 11 and the socket 4 when the ball stud 2 swings.

[0031] Next, a method for manufacturing the socket 4 of the ball joint 1 and a method for manufacturing the ball joint 1 will be described according to one embodiment.

[0032] First, in the forming process, as shown in Figure 1(a), the main body 20 of the socket 4 is formed into a bottomed cylindrical shape with an opening 26 at one end. At this time, the main body 20 is formed into a straight cylindrical shape in which the side wall 22 does not bend across one end and the side wall 22 has a constant or substantially constant inner diameter.

[0033] Next, after the forming process, the main body 20 undergoes a washing process in which it is washed with water and a drying process in which it is dried. In the roughening process, the main body 20 is roughened in the necessary areas of the inner circumferential surface 25 to form a roughened surface area 35. The roughened surface area 35 is formed using, for example, the processing device 50 shown in Figure 4. In this embodiment, the processing device 50 preferably uses a laser marker having a holding base 51 for holding the main body 20 and a laser irradiation unit 52 for irradiating the main body 20 held on the holding base 51 with a laser L.

[0034] The main body 20 is held on the support base 51 with the opening 26 facing upward.

[0035] The laser irradiation unit 52 is, for example, movably mounted. In the illustrated example, there are multiple laser irradiation units 52, for example, a pair, positioned on opposite sides (left and right in the figure) with respect to the center of the holding base 51. However, there may be one laser irradiation unit 52 or three or more.

[0036] The processing apparatus 50 then irradiates the main body 20, which is fixed in the irradiation position by the holding base 51, with a laser L from the laser irradiation unit 52 through the opening 26 onto the inner circumferential surface 25. At this time, it is preferable that the laser irradiation unit 52 irradiates the inner circumferential surface 25 of the main body 20 with the laser L in the circumferential direction in areas A of a predetermined angle (predetermined width). In other words, since the laser L has a focal length, it is difficult to irradiate a wide area of ​​the inner circumferential surface 25 with the desired intensity, so in order to ensure the accuracy of rough surface processing, it is preferable to irradiate each of the predetermined narrow areas A.

[0037] As shown in Figure 1(b), the above-mentioned region A is a rectangular region obtained by dividing the inner circumferential surface 25 of the main body 20 into a predetermined number of equal parts in the circumferential direction, for example, 10 to 12 in this embodiment. The regions A (Figure 1(b)) to which each laser irradiation unit 52 irradiates with the laser L shown in Figure 4 are preferably different from each other. Preferably, the laser irradiation unit 52 irradiates with the laser L to regions A (Figure 1(b)) that are separated by angles equal to the number of laser irradiation units 52 dividing 360° in the circumferential direction of the main body 20. In this embodiment, the laser irradiation unit 52 irradiates with the laser L in the circumferential and axial directions to regions A (Figure 1(b)) that are opposite each other, that is, 180° apart from each other, with respect to the central axis of the main body 20.

[0038] Preferably, the laser L is irradiated at the same position at least twice to cause evaporation in the material on the inner circumferential surface 25 of the main body 20 at that position. The lasers L irradiated from each laser irradiation unit 52 are arranged in different phases to prevent interference even if they intersect.

[0039] As a result, as shown in Figure 1(c), the material (material M1) constituting the inner circumferential surface 25 evaporates at the position where the laser L is irradiated, and the material (molten material M2) surrounding the evaporated portion melts and is pushed out by the irradiation pressure of the laser L, forming a recess 37. Furthermore, the molten material M2 pushed out from the recess 37 towards the surface side of the inner circumferential surface 25 cools and solidifies again upon contact with the outside air, forming a protrusion 38 on the outer edge of the recess 37. Multiple recesses 37 and their corresponding protrusions 38 are formed regularly or irregularly in each region A (Figure 1(b)).

[0040] When the laser irradiation unit 52 finishes irradiating one region A with the laser L, it similarly irradiates the region A adjacent to that region A in the circumferential direction of the main body 20 with the laser L, thereby performing surface roughening on all regions A in the same manner.

[0041] Furthermore, the remaining portion of the inner circumferential surface 25, excluding the roughened portion 35 where the recesses 37 and protrusions 38 are formed, becomes the unroughened portion 40 shown in Figure 1(a). Note that, although the unroughened portion 40 is not subjected to roughening, other surface treatments may be applied as long as the surface roughness of the unroughened portion 40 is less than that of the roughened portion 35.

[0042] Furthermore, after the surface roughening process, as an insertion process, a ball seat 3, which rotatably holds the ball portion 10 of a separately formed ball stud 2, is inserted from the opening 26 into the interior (inner chamber 24) of the main body 20 of the socket 4.

[0043] Then, following the insertion process, a bending process is performed in which the portion of the socket 4 from the equator position E of the ball portion 10, which is a predetermined position, to the end portion having the opening 26 is bent toward the central axis by crimping deformation or the like to form a bent portion 28, which prevents the ball seat 3 inserted inside from coming out. The end face of one end of the socket 4 is formed as an expanded portion 42 by the bending process.

[0044] After this, dust covers and other components are attached to the ball stud 2 and socket 4 as needed, and the opening 26 is covered with the dust cover to complete the ball joint 1.

[0045] By forming it in this way, the roughened portion 35 of the socket 4 bites into the outer surface of the seat bend portion 18 of the ball seat 3, creating an anchoring effect and preventing the ball seat 3 from falling out of the socket 4, i.e., preventing seat flow.

[0046] As described above, by forming at least one recess 37 on the inner circumferential surface 25 of the main body 20, and by forming a protrusion 38 rising from the inner circumferential surface 25 on the edge of the recess 37, the surface roughness of the inner circumferential surface 25 can be made rougher, thereby increasing the frictional force of the contact surface between the inner circumferential surface 25 and the bearing seat 3. Therefore, when a load is applied from the ball stud 2 to the socket 4 in the compressive and tensile directions, the bearing seat 3 can be firmly held in the socket 4 by frictional force, making it difficult for the bearing seat 3 to move within the main body 20 of the socket 4, thereby improving the pull-out strength, compressive strength, and thus the durability performance.

[0047] Furthermore, such recesses 37 and protrusions 38 can be formed by, for example, irradiating the inner circumferential surface 25 of a cylindrical main body 20 made of metal with a laser to melt the material to form the recesses 37, and by solidifying the molten material that is extruded from the recesses 37 to the edges of the recesses 37 by the laser irradiation pressure. In other words, in the conventional method of roughening the surface roughness of the inner circumferential surface 25 by, for example, a film treatment with phosphoric acid, the surface treatment takes time, so it is necessary to keep the workpiece in the process and discharge the workpiece that has finished being treated at the same time as the workpiece is introduced. In such a method, when changing the type of workpiece (setup change), it takes time not only to discharge all the workpieces in the process and refill the process with workpieces, but also to manage the chemicals used for surface treatment, treat wastewater, and check to maintain the concentration suitable for surface treatment, which requires a lot of production energy. In contrast, if the recesses 37 and protrusions 38 are formed by melting and solidifying the material constituting the inner circumferential surface 25 of the main body 20 using a laser L, surface treatment can be performed in a short time, the number of steps is reduced compared to conventional methods, workpiece type changes can be made quickly and easily, and chemical management is unnecessary, thus enabling manufacturing with an environmentally friendly processing method while improving productivity.

[0048] In particular, by irradiating the same position on the inner circumferential surface 25 of the main body 20 with the laser L at least twice, the material of the main body 20 can be reliably evaporated and melted, making it easy to form the recessed portion 37 and the convex portion 38.

[0049] In the bent portion 28 of the main body 20, which is deformed to hold the bearing seat 3, a recess 37 and a protrusion 38 are formed on at least the inner circumferential surface of the bent portion 28. When the bent portion 28 is deformed, the roughened surface portion 35 consisting of the recess 37 and the protrusion 38 bites into the outer circumferential surface of the bearing seat 3, making it difficult for the bearing seat 3 to move within the main body 20 of the socket 4.

[0050] By forming the recessed portion 37 and the convex portion 38 over at least the entire circumference of the inner surface of the bent portion 28, the bearing seat 3 can be made less likely to move within the main body portion 20 of the socket 4, thereby improving durability.

[0051] By regularly forming recesses 37 on the inner circumferential surface 25, the arrangement of the recesses 37 and the protrusions 38 formed on their edges can be controlled, making it easy to control durability performance, and allowing the recesses 37 and protrusions 38 to be easily manufactured using a laser L.

[0052] In the above embodiment, the ball joint 1 is not limited to the steering system of a vehicle, but can also be used in, for example, a suspension system or other devices.

[0053] Furthermore, the ball joint 1 described above can be used not only for vehicles but also for any other application. [Industrial applicability]

[0054] The present invention can be suitably used, for example, in steering systems of vehicles such as automobiles. [Explanation of Symbols]

[0055] 1. Ball joint 3 Bearing Seats 4 sockets 10 Ball Club 20 Main body 25 Inner surface 28. Bending section 37 Recess 38 Convex part L Laser M2 molten material

Claims

1. A cylindrical metal body that holds the bearing seat, Multiple recesses formed on the inner surface of this main body, Each of the recesses has a protrusion formed on its edge and rising from the inner circumferential surface, The recesses and protrusions are formed to bite into the bearing seat and hold it in place, and are regularly formed at positions far apart from each other so as not to be connected to each other. The recess is a hemispherical dimple, The aforementioned protrusion is a molten and solidified metal body that makes up the main body. It is formed in a continuous, seamless manner from the inner surface of the recess to the top of the protrusion. A ball joint socket characterized by the following features.

2. The main body has a bend that deforms to hold the bearing seat, The recesses and protrusions are located at least on the inner circumferential surface of the bent portion. A ball joint socket according to feature 1.

3. The recesses and protrusions are located at least around the entire circumference of the inner surface of the bent portion. The ball joint socket according to feature 2.

4. A cylindrical bearing seat, A ball portion is rotatably held within this bearing seat, A socket according to any one of claims 1 to 3, which holds the bearing seat that holds the ball portion, A ball joint characterized by having the following features.

5. A method for manufacturing a ball joint socket according to any one of claims 1 to 3, The cylindrical body is formed from metal. By irradiating the inner circumferential surface of the main body from the outside of the main body with a laser, a plurality of recesses and a plurality of protrusions formed by the solidification of molten material extruded from these recesses to their edges are regularly formed at positions far apart from each other, such that the recesses and protrusions do not connect to each other. A method for manufacturing a ball joint socket, characterized by the following:

6. The laser is irradiated at the same position on the inner surface of the main body at least twice. A method for manufacturing a ball joint socket according to claim 5, characterized in that it is a method for manufacturing a ball joint socket.

7. The direction of laser irradiation is inclined with respect to the axial direction of the main body. A method for manufacturing a ball joint socket according to claim 5, characterized in that it is a method for manufacturing a ball joint socket.

8. The inner surface of the main body is divided into multiple regions in the circumferential direction and laser irradiation is performed sequentially for each region. A method for manufacturing a ball joint socket according to claim 5, characterized in that it is a method for manufacturing a ball joint socket.

9. Lasers are irradiated from opposite sides with respect to the central axis of the main body. A method for manufacturing a ball joint socket according to claim 5, characterized in that it is a method for manufacturing a ball joint socket.

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