A composite body, a method for manufacturing a composite body, and a buffer.

Abstract

To provide a coupling body capable of improving the strength of a connection part between a rod-shaped member and a mate member, a method for manufacturing a coupling body, and a buffer using them.SOLUTION: Since a finished surface roughness (surface roughness) of surface roughness adjustment parts 57, 58 is larger (rougher) than a finished surface roughness of pressure receiving surfaces 55A, 56A before surface roughness adjustment or a finished surface roughness of pressure receiving surfaces 55B, 56B without surface roughness adjustment, a frictional force (frictional resistance) generated between a material of a solenoid case 31 (mate member) that has flowed into first annular grooves 55, 56 and the inner surfaces of the first annular grooves 55, 56 of a piston rod 51 (rod-shaped member) increases, so that it is possible to improve the strength of a connection part 12 between the piston rod 51 and the solenoid case 31.SELECTED DRAWING: Figure 4

Description

【Technical Field】 【0001】 The present invention relates to a combination of two members joined by a plastic flow bonding method, a method for manufacturing the combination, and a shock absorber manufactured by the manufacturing method. 【Background Art】 【0002】 Patent Document 1 discloses a method for joining two members in which a piston rod (rod-shaped member) and a solenoid case (counterpart member) are joined by a plastic flow bonding method. 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2009-202193 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 By the way, in a piston-integrated type damping force adjustable hydraulic shock absorber in which a piston mechanism is built in a cylinder, since the control valve is arranged coaxially with the piston rod, the effective stroke is shorter than that of a control valve side-mounted type damping force adjustable hydraulic shock absorber or a conventional hydraulic shock absorber. In such a piston-integrated type damping force adjustable hydraulic shock absorber, since the solenoid case receives a rebound load, it is necessary to increase the strength of the joint portion between the piston rod and the solenoid case. 【0005】 An object of the present invention is to provide a combination capable of increasing the strength of the joint portion between a rod-shaped member and a counterpart member, a method for manufacturing the combination, and a shock absorber manufactured by the manufacturing method. 【Means for Solving the Problems】 【0006】 The present invention relates to a two-member joint in which one end of a rod-shaped member is fitted into a fitting hole of a mating member, and the material of the mating member is plastically flowed into an annular groove provided on the circumferential surface of one end of the rod-shaped member, wherein a friction generating means is provided on the inner surface of the annular groove, and the friction generating means is a projection or groove extending in the axial direction of the rod-shaped member on the inner surface of the annular groove. The present invention provides a method for manufacturing a composite body of two members, which is bonded by fitting one end of a rod-shaped member into a fitting hole of a mating member and causing the material of the mating member to undergo plastic flow and flow into a groove provided on the circumferential surface of one end of the rod-shaped member, characterized in that the method comprises: a groove forming step of forming the groove on the circumferential surface of one end of the rod-shaped member; a surface roughness adjustment step of making the surface roughness of the inner surface of the groove of the rod-shaped member rougher; and a plastic flow step of causing the material of the mating member to flow into the groove of the rod-shaped member. The buffer of the present invention comprises a cylinder in which a working fluid is sealed, a piston mechanism that divides the inside of the cylinder into two chambers, a piston rod whose one end is coupled to the piston mechanism and whose other end extends to the outside of the cylinder, and a coupling portion formed by fitting one end of the piston rod into a fitting hole of the piston mechanism and causing the material of the piston mechanism to plastically flow into a groove provided on the circumferential surface of one end of the rod-shaped member, wherein the inner surface of the groove is groove The inner surface of the rod-shaped member is provided with friction generating means, which are projections or grooves extending in the axial direction of the rod-shaped member. [Effects of the Invention] 【0007】 According to the present invention, the strength of the joint between the rod-shaped member and the mating member can be increased. [Brief explanation of the drawing] 【0008】 [Figure 1] This is a cross-sectional view of a portion of the buffer according to the first embodiment, taken from the axial plane. [Figure 2] This is a cross-sectional view of the combined body according to the first embodiment, along the axial plane. [Figure 3]This is an enlarged view of section A in Figure 2. [Figure 4] This is an explanatory diagram of the manufacturing method according to the first embodiment, and is a conceptual diagram of the cutting process in the surface roughness adjustment step. [Figure 5] This is an explanatory diagram of theoretical roughness. [Figure 6] This is an explanatory diagram of the manufacturing method according to the first embodiment, showing the state before pressurization. [Figure 7] This is an explanatory diagram of the manufacturing method according to the first embodiment, showing the state in which the second annular recess is formed. [Figure 8] This is an explanatory diagram of the manufacturing method according to the first embodiment, showing the state in which the first annular recess is formed. [Figure 9] This is an explanatory diagram of the manufacturing method according to the first embodiment, and is a conceptual diagram of another form of cutting in the surface roughness adjustment process. [Figure 10] This is a conceptual diagram of the second embodiment. [Figure 11] This is a conceptual diagram of another embodiment of the second embodiment. [Figure 12] This is a conceptual diagram of another embodiment of the second embodiment. [Figure 13] This is a conceptual diagram of the third embodiment, where (a) is a cross-sectional view and (b) is a front view. [Figure 14] This is a conceptual diagram of another embodiment of the third embodiment, where (a) is a cross-sectional view and (b) is a front view. [Modes for carrying out the invention] 【0009】 (First Embodiment) A first embodiment of the present invention will be described with reference to the attached figures. Figure 1 is a cross-sectional view, taken from the axial plane, of a part of a piston-integrated type damping force adjustable hydraulic shock absorber 1 (hereinafter referred to as "shock absorber 1") in which the piston mechanism 21 is built into the cylinder 2. For convenience, the vertical direction in Figure 1 will be referred to as the "vertical direction". 【0010】 As shown in FIG. 1, the piston mechanism 21 has a piston 3 and a damping force adjustment mechanism 22. The piston 3 is fitted into the cylinder 2 and divides the inside of the cylinder 2 into two chambers, i.e., a cylinder upper chamber 2A and a cylinder lower chamber 2B. The piston mechanism 21 is coupled to the lower end portion 52 (one end portion) of the piston rod 51. The upper end portion (the other end portion, not shown) of the piston rod 51 extends to the outside of the cylinder 2. Note that the piston rod 51 is a hollow shaft having a hollow portion 53 formed therein. 【0011】 The damping force adjustment mechanism 22 has a valve mechanism portion 23 and a solenoid 24. Note that the configuration of the shock absorber 1 excluding the joint portion 12 of the combined body 11 (see FIG. 2) of the piston rod 51 and the piston mechanism 21 is the same as that of the conventional shock absorber. Therefore, for the purpose of simplifying the description in the specification, a detailed description of the damping force adjustment mechanism 22 will be omitted. 【0012】 FIG. 2 is a cross-sectional view taken along the axial plane of the combined body 11 of two members, i.e., the piston rod 51 (rod-shaped member) and the solenoid case 31 (mating member). FIG. 3 is an enlarged view of the joint portion 12 (portion A in FIG. 2) of the combined body 11. As shown in FIG. 2, the solenoid case 31 is formed in a lid-shaped cylindrical shape with an open lower end. A fitting hole 33 into which the lower end portion 52 of the piston rod 51 is fitted is provided at the center of the lid portion 32 of the solenoid case 31. Note that the internal components of the solenoid 24 (see FIG. 1) are housed in the solenoid case 31. Further, a bump stopper 4 (see FIG. 1) is abutted against the upper end surface 34 of the solenoid case 31. 【0013】 As shown in FIG. 3, the combined body 11 is obtained by fitting the lower end portion 52 of the piston rod 51 into the fitting hole 33 of the solenoid case 31 of the piston mechanism 21 in a plastic flow process described later, and locally pressurizing the solenoid case 31 in this state, thereby plastically flowing the material of the solenoid case 31 into the first annular grooves 55, 56 and the second annular groove 59 provided on the outer peripheral surface 54 (circumferential surface) of the lower end portion 52 of the piston rod 51. 【0014】 The first annular grooves 55 and 56 extend circumferentially along the outer surface 54 of the piston rod 51, and their cross-section along the axial plane is formed as an isosceles right triangle with a vertex angle θ1 (see Figure 4). That is, the vertex angle θ1 is 90 degrees. The first annular groove 56 is located directly above the first annular groove 55, and its width W1 in the axial direction ("up and down direction" in Figure 3) and depth D1 in the radial direction ("left and right direction" in Figure 3) are set to be the same as those of the first annular groove 55. The second annular groove 59, like the first annular grooves 55 and 56, is formed as an isosceles right triangle with a vertex angle of 90 degrees in its cross-section along the axial plane, and is located at a distance Y axially above the first annular groove 56. The second annular groove 59 has a width W2 and depth D2 that are smaller than the width W1 and depth D1 of the first annular grooves 55 and 56. 【0015】 A first annular recess 36, having a channel-shaped cross-section according to the axial plane of the connecting body 11, is provided on the inner circumference side of the lower end surface 35 of the lid 32 of the solenoid case 31 (near the fitting hole 33 and the first annular groove 55). On the other hand, a second annular recess 37, having a channel-shaped cross-section according to the axial plane of the connecting body 11, is provided on the inner circumference side of the upper end surface 34 of the lid 32 of the solenoid case 31 (near the fitting hole 33 and the second annular groove 59). The radial width W3 and axial depth D3 of the first annular recess 36 are set to be larger than the radial width W4 and axial depth D4 of the second annular recess 37. In other words, the volume of the first annular recess 36 is set to be larger than the volume of the second annular recess 37. 【0016】 Furthermore, the material used for the solenoid case 31 (the mating component) is a softer metal than the material used for the piston rod 51 (the rod-shaped component). For example, the material for the piston rod 51 is S45C carbon steel for machine structural use, while the material for the solenoid case 31 is S10C carbon steel for machine structural use (free-cutting steel). 【0017】 In the first embodiment, surface roughness adjustment sections 57 and 58 (friction generating means) are provided on the inner surfaces of the first annular grooves 55 and 56 of the piston rod 51. As shown in Figure 4, the surface roughness adjustment sections 57 and 58 are machined surfaces obtained by machining (turning) the pressure-receiving surfaces 55A and 56A of the piston rod 51 that receives pressure during the extension stroke of the shock absorber 1. The surface roughness adjustment sections 57 and 58 have a larger finished surface roughness (surface roughness) than the pressure-receiving surfaces 55B and 56B of the piston rod 51 that receives pressure during the contraction stroke of the shock absorber 1. 【0018】 Referring to Figure 5, when the surface roughness (theoretical roughness) in cutting is h [μm], the feed rate of the cutting edge 41 (tool) per revolution of the piston rod 51 (workpiece, see Figure 4) is f [mm / rev], and the corner radius of the insert of the cutting edge 41 (e.g., "throwaway chip", see Figure 4) is RE [mm], then h = (f 2 The thickness is ( / 8RE) × 1000 [μm]. 【0019】 Therefore, in the first embodiment, in the surface roughness adjustment process described later, a cutting edge 41 with a small corner radius (RE) of the insert is used, and the feed rate (f) is set to a large value, thereby roughening the surface roughness adjustment sections 57, 58, and consequently the pressure-receiving surfaces 55A, 56A of the first annular grooves 55, 56. Here, the feed rate (f) in the surface roughness adjustment process is larger than the feed rate recommended by the tool manufacturer. 【0020】 Next, a manufacturing method for the combined body 11 of the two members, the piston rod 51 (rod-shaped member) and the solenoid case 31 (counter member), will be described. (Groove formation process) In the groove formation process, a first annular groove 55, 56 and a second annular groove 59 are formed on the outer circumferential surface 54 of the lower end portion 52 (one end portion) of the piston rod 51 by cutting, plastic deformation, etc. 【0021】 (Surface roughness adjustment process) In the surface roughness adjustment process, as shown in Figure 4, a cutting blade 41 with an acute tip angle θ2 is used to cut the pressure-receiving surfaces 55A and 56A of the piston rod 51 that receives pressure (receives rebound load) during the extension stroke of the shock absorber 1, thereby forming surface roughness adjustment sections 57 and 58 on the inner surfaces of the first annular grooves 55 and 56 of the piston rod 51. As shown in Figure 4, in the surface roughness adjustment process, the end face 42 of the cutting blade 41 in the feed direction is positioned parallel to the pressure-receiving surfaces 55B and 56B. 【0022】 (Plastic flow process) In the plastic flow process, as shown in Figure 6, the lower end portion 52 of the piston rod 51 is fitted into the fitting hole 33 of the solenoid case 31, and the lid portion 32 of the solenoid case 31 is restrained by a jig 45. In this state, the vicinity of the fitting hole 33 on the lower end surface 35 of the lid portion 32 of the solenoid case 31 is locally pressurized by a first punch 46 of a press device (not shown), and the vicinity of the fitting hole 33 on the upper end surface 34 is locally pressurized by a second punch 47. 【0023】 Then, based on Tresca's deformation conditions, first, the material of the solenoid case 31 facing the second annular groove 59 undergoes deformation (plastic flow) into the second annular groove 59, and as shown in Figure 7, the material of the solenoid case 31 fills the second annular groove 59, and a second annular recess 37 is formed on the upper end surface 34 of the lid portion 32 of the solenoid case 31. Next, the material of the solenoid case 31 facing the first annular grooves 55, 56 undergoes deformation (plastic flow) into the first annular grooves 55, 56, and as shown in Figure 8, the material of the solenoid case 31 fills the first annular grooves 55, 56, and a first annular recess 36 is formed on the lower end surface 35 of the lid portion 32 of the solenoid case 31. 【0024】 In a piston-integrated, damping-adjustable hydraulic shock absorber, the solenoid case is subjected to rebound load, therefore, it was necessary to improve the strength of the connection between the piston rod and the solenoid case. 【0025】 Therefore, in the first embodiment, the lower end 52 (one end) of the piston rod 51 (rod-shaped member) is fitted into the fitting hole 22 of the solenoid case 31 (mating member) of the piston mechanism 21, and the material of the solenoid case 31 is plastically flowed and flows into the first annular grooves 55, 56 and the second annular groove 59 provided on the outer peripheral surface 54 of the lower end 52 of the piston rod 51 to form a joint 11 of two members. Surface roughness adjustment parts 57, 58 (friction generating means) are provided on the pressure receiving surfaces 55A, 56A of the first annular grooves 55, 56 of the piston rod 51, which receive the load (rebound load) during the extension stroke of the buffer 1, to form a joint 12. In the first embodiment, the surface roughness of the surface roughness adjustment sections 57 and 58 is made greater (rougher) than the surface roughness of the pressure receiving surfaces 55A and 56A before surface roughness adjustment, or the surface roughness of the pressure receiving surfaces 55B and 56B without surface roughness adjustment. This makes it possible to increase the frictional force (frictional resistance) generated between the material of the solenoid case 31 that flows into the first annular grooves 55 and 56 and the inner surface of the first annular grooves 55 and 56 of the piston rod 51, thereby improving the strength of the joint 12 between the piston rod 51 and the solenoid case 31. As a result, it is possible to prevent the piston rod 51 from coming loose from the solenoid case 31. 【0026】 Furthermore, in the first embodiment, in the surface roughness adjustment process, the end face 42 of the cutting edge 41 in the feed direction is positioned parallel to the pressure receiving surfaces 55B and 56B to increase the cutting resistance, thereby making the pressure receiving surfaces 55A and 56A rougher. As shown in Figure 9, in the surface roughness adjustment process, the cutting blade 41 is positioned such that the angle between the end face 42 of the cutting blade 41 and the pressure receiving surfaces 55B, 56B is the same as the angle between the end face 43 of the cutting blade 41 and the pressure receiving surfaces 55A, 56A, with the tip of the cutting blade 41 in contact with the vertex P of the annular grooves 55, 56. In other words, the cutting blade 41 is positioned so that the input direction of the cutting blade 41 is perpendicular to the axis of the piston rod 51, and the pressure receiving surfaces 55A, 56A and 55B, 56B are cut in a single pass. This forms surface roughness adjustment sections 57, 58 on the pressure receiving surfaces 55A, 56A and 55B, 56B, allowing for surface roughness adjustment of the pressure receiving surfaces 55A, 56A and 55B, 56B. 【0027】 (Second Embodiment) Next, a second embodiment will be described with reference to Figure 10. Regarding parts common to the first embodiment, the same designations and symbols will be used, and redundant explanations will be omitted. 【0028】 In the first embodiment, during the surface roughness adjustment process, the pressure-receiving surfaces 55A and 56A of the first annular grooves 55 and 56, which receive the load (rebound load) during the extension stroke of the shock absorber 1, are cut at a feed rate (f) greater than the recommended feed rate, thereby forming surface roughness adjustment sections 57 and 58 (friction generating means and cut surfaces) on the pressure-receiving surfaces 55A and 56A of the piston rod 51. 【0029】 In contrast, in the second embodiment, projections 61 extending intermittently in the circumferential direction, that is, multiple projections 61 arranged along the circumferential direction, are provided on the pressure-receiving surfaces 56A and 56B of the first annular groove 55 and the second annular groove 56 of the piston rod 51 (rod-shaped member), thereby forming surface roughness adjustment sections 57 and 58 (friction generating means) on the pressure-receiving surfaces 55A and 55B and 56A and 56B of the piston rod 51. 【0030】 The projections 61 are provided on the pressure-receiving surfaces 55A, 55B and 56A, 56B in multiple stages (two stages in the second embodiment) spaced apart in the axial direction of the piston rod 51 (the "up and down direction" in Figure 10). The projections 61 also have a cross-section of a right-angled isosceles triangle with respect to the axial plane of the piston rod 51. The projections 61 have a bottom surface 62 perpendicular to the axis L of the piston rod 51 and a side surface 63 parallel to the axis L of the piston rod 51. 【0031】 In the second embodiment, during the plastic flow process, the material of the solenoid case 31 (mating member) is filled into the first annular grooves 55, 56 of the piston rod 51, which have protrusions 61 on the pressure-receiving surfaces 55A, 55B and 56A, 56B. As a result, the contact area between the inner surfaces of the annular grooves 55, 56 of the piston rod 51 and the solenoid case 31 is increased compared to the first embodiment, and the strength of the joint 12 between the piston rod 51 and the solenoid case 31 can be improved. In the second embodiment, it is possible to exert a greater resistance force to the rotational torque acting on the joint 12 than in the first embodiment. 【0032】 As shown in Figure 11, instead of the projection 61, grooves 65 extending intermittently in the circumferential direction, i.e., multiple grooves 65 arranged along the circumferential direction, can be provided on the pressure-receiving surfaces 55A, 55B of the first annular groove 55 and the pressure-receiving surfaces 56A, 56B of the first annular groove 56 of the piston rod 51, thereby forming surface roughness adjustment sections 57, 58 (friction generating means) on the pressure-receiving surfaces 55A, 55B and 56A, 56B of the piston rod 51. Furthermore, in the second embodiment, the surface roughness adjustment sections 57 and 58 can be made into projections 61 or grooves 65 that extend continuously in the circumferential direction over the pressure-receiving surfaces 55A and 55B of the first annular groove 55 and the pressure-receiving surfaces 56A and 56B of the first annular groove 56 of the piston rod 51. Furthermore, as shown in Figure 12, instead of protrusions 61 or grooves 65, the pressure-receiving surfaces 55A, 55B of the first annular groove 55 and the pressure-receiving surfaces 56A, 56B of the first annular groove 56 of the piston rod 51 are knurled, and irregularities are provided on the pressure-receiving surfaces 55A, 55B of the first annular groove 55 and the pressure-receiving surfaces 56A, 56B of the first annular groove 56 of the piston rod 51, thereby forming surface roughness adjustment parts 57, 58 (friction generating means) on the pressure-receiving surfaces 55A, 55B of the first annular groove 55 and the pressure-receiving surfaces 56A, 56B of the first annular groove 56 of the piston rod 51. 【0033】 (Third embodiment) Next, a third embodiment will be described with reference to Figures 13(a) and 13(b). Furthermore, for parts common to the first or second embodiment, the same designations and symbols will be used, and redundant explanations will be omitted. 【0034】 In the second embodiment, projections 61 extending intermittently in the circumferential direction are provided on the pressure-receiving surfaces 55A, 55B of the first annular groove 55 and 56A, 56B of the first annular groove 56 of the piston rod 51, thereby forming surface roughness adjustment sections 57, 58 (friction generating means) on the pressure-receiving surfaces 55A, 55B of the first annular groove 55 and 56A, 56B of the first annular groove 56. 【0035】 In contrast, in the third embodiment, projections 71 extending in the axial direction (the "up and down direction" in Figure 13) are provided between the pressure-receiving surfaces 55A and 55B of the first annular groove 55 of the piston rod 51 (rod-shaped member), and between the pressure-receiving surfaces 56A and 56B of the first annular groove 56, thereby forming surface roughness adjustment sections 57 and 58 (friction generating means) in the first annular grooves 55 and 56 of the piston rod 51 (rod-shaped member). The projections 71 have a width W5 and are provided in the first annular grooves 55 and 56 at regular intervals in the circumferential direction. 【0036】 In the third embodiment, during the plastic flow process, the material for the solenoid case 31 (mating member) is filled between adjacent protrusions 71 of the first annular groove 55 and between adjacent protrusions 71 of the first annular groove 56. This increases the contact area between the inner surfaces of the annular grooves 55 and 56 of the piston rod 51 and the solenoid case 31 compared to the first embodiment, thereby improving the strength of the joint 12 between the piston rod 51 and the solenoid case 31. Furthermore, the protrusions 71 can exert a greater resistance force against the rotational torque acting on the joint 12 than the protrusions 61 in the second embodiment. 【0037】 As shown in Figures 14(a) and 14(b), instead of the projection 71, grooves 75 extending vertically along the pressure-receiving surfaces 55A, 55B and 56A, 56B are provided on the pressure-receiving surfaces 55A, 55B and 56A, 56B of the first annular groove 55 and the first annular groove 56 of the piston rod 51, thereby forming surface roughness adjustment sections 57, 58 (friction generating means) on the pressure-receiving surfaces 55A, 55B of the first annular groove 55 and 56A, 56B of the first annular groove 56 of the piston rod 51. The grooves 75 are formed in an isosceles trapezoidal shape in cross-section with respect to the axial plane of the piston rod 51. 【0038】 The embodiments are not limited to the forms described above, and can be configured as follows, for example. In the embodiments described above, an example was given in which the surface roughness adjustment parts 57, 58 (friction generating means) are formed by machining the piston rod 51 (rod-shaped member). However, the surface roughness adjustment parts 57, 58 (friction generating means) can also be formed on the pressure-receiving surfaces 55A, 55B of the first annular groove 55 and the pressure-receiving surfaces 56A, 56B of the first annular groove 56 of the piston rod 51 by chemically treating them with chemicals such as nital and picric acid. [Explanation of symbols] 【0039】 11 Joint, 12 Joint, 31 Solenoid case (mating member), 33 Fitting hole, 51 Piston rod (rod-shaped member), 52 Lower end (one end of rod-shaped member), 55, 56 First annular groove (annular groove), 55A, 55B, 56A, 56B Pressure receiving surface (inner surface of annular groove), 57, 58 Surface roughness adjustment part (friction generating means)

Claims

[Claim 1] A two-member assembly formed by fitting one end of a rod-shaped member into a fitting hole of a mating member, and causing the material of the mating member to undergo plastic flow and flow into an annular groove provided on the circumferential surface of one end of the rod-shaped member, A friction generating means is provided on the inner surface of the annular groove. The friction generating means is a coupling characterized by a projection or groove that extends continuously or intermittently in the circumferential direction along the inner surface of the annular groove. [Claim 2] The composite according to claim 1, The friction generating means is a coupling characterized by a projection or groove extending in the axial direction of the rod-shaped member on the inner surface of the annular groove. [Claim 3] A method for manufacturing a joint of two members, in which one end of a rod-shaped member is fitted into a fitting hole of a mating member, and the material of the mating member is plastically flowed into a groove provided on the circumferential surface of the one end of the rod-shaped member to join them together, A groove forming step in which the groove is formed on the circumferential surface of one end of the rod-shaped member, A surface roughness adjustment step to make the surface roughness of the inner surface of the groove of the rod-shaped member rougher, A plastic flow process in which the material of the mating member flows into the groove of the rod-shaped member, A method for producing a compound, characterized by having the following characteristics. [Claim 4] A method for manufacturing the composite according to claim 3, A method for manufacturing a composite, characterized in that, in the surface roughness adjustment step, the inner surface of the groove of the rod-shaped member is machined at a feed rate greater than the feed rate of the recommended cutting conditions. [Claim 5] A cylinder in which the working fluid is sealed, A piston mechanism that divides the inside of the cylinder into two chambers, A piston rod, with one end connected to the piston mechanism and the other end extending to the outside of the cylinder, A joint is formed by fitting one end of the piston rod into the fitting hole of the piston mechanism and causing the material of the piston mechanism to undergo plastic flow and flow into a groove provided on the circumferential surface of one end of the rod-shaped member, A shock absorber equipped with, A buffer characterized in that friction generating means, which are projections or grooves extending in the axial direction of the rod-shaped member, are provided on the inner surface of the groove.

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