Manufacturing method of a sliding member for shock absorber, manufacturing method of a shock absorber, sliding member for shock absorber and shock absorber

Abstract

To provide a manufacturing method of a slide member which enables improvement of retention of a lubrication oil between slide members while improving operability and can keep smooth sliding of the slide member, and to provide a manufacturing method of a buffer, the slide member, the buffer, and a riding quality adjustment method.SOLUTION: A manufacturing method of a slide member which slides in the presence of a lubrication oil includes: a first polishing step in which a surface of the slide member is polished in a circumferential direction of the slide member by using a polishing tape having a first grind stone to form multiple grooves going around in the circumferential direction at the slide member; and a second polishing step in which the slide member after the first polishing step is polished to form a cross section of the surface as seen in a longitudinal direction of the slide member into a plateau shape.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to For shock absorbers Manufacturing method of sliding member, manufacturing method of shock absorber, For shock absorbers Sliding members and cushioning In a vessel Regarding. [Background technology]

[0002] 2. Description of the Related Art Conventionally, a technique for mechanically polishing an outer peripheral surface of a piston rod of a shock absorber in order to improve the operability of the shock absorber has been known (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-042208 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the outer circumferential surface of the piston rod is mirror-finished to allow the piston rod to slide smoothly in a shock absorber, the lubricating oil that should be present between sliding members such as the piston rod and the seal member leaks out from between the sliding members, and squeeze-out occurs, in which the lubricating oil cannot be retained between the sliding members (or in the oil pool).Therefore, there has been a demand for a sliding member and a shock absorber that can maintain smooth sliding of the sliding members by improving the retention of the lubricating oil between the sliding members while improving operability.

[0005] The present invention can improve the retention of lubricating oil between the sliding members while improving operability, and can maintain smooth sliding of the sliding members. For shock absorbers Manufacturing method of sliding member, manufacturing method of shock absorber, For shock absorbers Sliding member and buffer Vessel The aim is to provide. [Means for solving the problem]

[0006] The present invention relates to the following (1) to (7): For shock absorbers The present invention relates to a method for manufacturing a sliding member. (1) Sliding motion is performed in the presence of lubricant For shock absorbers A method for manufacturing a slide member, comprising the steps of: The shock absorber sliding member is a cylindrical rod, and the outer circumferential surface of the rod The above-mentioned is polished by using a polishing tape having a first grindstone. Rod Grind in the circumferential direction, rod a first polishing step for forming a plurality of grooves in a circumferential direction on the surface of the substrate; rod Polishing the above rod In the longitudinal direction Outer surface A second polishing step for forming a cross section into a plateau shape. In the first polishing step, the polishing tape is fed out while the rod is being rotated, and the polishing tape is brought into contact with the rod for polishing, and a feed speed of the polishing tape is 1 / 10 or less relative to a rotation speed of the rod. A method for manufacturing a sliding member. (2) The first grindstone has an average grain size of 15 to 100 μm. For shock absorbers A method for manufacturing a sliding member. (3) The second polishing step is performed by using a polishing tape having a second grindstone having an average grain size smaller than that of the first grindstone. Rod The above-mentioned (1) or (2) is ground in the circumferential direction. For shock absorbers A method for manufacturing a sliding member. (4) The second grindstone has an average grain size of 0.1 to 12 μm, as described in any one of (1) to (3) above. For shock absorbers A method for manufacturing a sliding member. ( 5 In the first polishing step, Rotate the rod While rotating the polishing tape, the polishing tape is fed out. rod The polishing is performed by contacting the rod The above for the turning speed rod In the longitudinal direction of rod and the polishing tape, the relative moving speed of which is 1 / 100 or less. 4 ) For shock absorbers A method for manufacturing a sliding member. ( 6 In the first polishing step, the polishing tape is rod The present invention relates to any one of the above (1) to (5), which does not perform oscillation by moving the same back and forth in the longitudinal direction. For shock absorbers A method for manufacturing a sliding member.

[0007] The present invention relates to the following: 7 The gist of the present invention is a manufacturing method for a shock absorber. ( 7 )Above (1) to ( 6 ) For shock absorbers A shock absorber is manufactured using the manufacturing method of the sliding member. For shock absorbers A method for manufacturing a shock absorber, comprising the steps of: manufacturing a sliding member.

[0010] The present invention relates to the following: 8 The gist of the present invention is a method for manufacturing a sliding member for a shock absorber. ( 8 ) A method for manufacturing a shock absorber sliding member according to any one of (1) to (6) above. A method for manufacturing a shock absorber sliding member according to any one of (1) to (6) above, wherein, when polishing a shock absorber sliding member used in a shock absorber of a moving body, the shock absorber sliding member is polished so that an outer peripheral surface cross section in the longitudinal direction has a plateau shape in order to adjust the ride comfort of the moving body using the shock absorber, and the load length ratio (tp) in the longitudinal direction is adjusted. Effect of the Invention

[0011] According to the present invention, it is possible to improve the retention of lubricating oil between the sliding members while improving operability, and thus to maintain smooth sliding of the sliding members. For shock absorbers Manufacturing method of sliding member, manufacturing method of shock absorber, For shock absorbers Sliding member and buffer Vessel can be provided. [Brief description of the drawings]

[0012] [Figure 1] 1 is a diagram for explaining a tape polishing device according to the present invention; [Diagram 2] FIG. 2 is a diagram showing a visualization of the measurement results of a piston rod polished by the polishing method according to the present embodiment, measured using a laser-type surface roughness measuring device. [Diagram 3]5 is a conceptual diagram for explaining a groove formed in the sliding member according to the embodiment. FIG. [Figure 4] 2 is a schematic diagram for explaining a surface cross section in a longitudinal direction of the sliding member according to the embodiment. FIG. [Diagram 5] FIG. 13 is a diagram showing the results of measuring the surface roughness of a piston rod of a shock absorber by using a laser type surface roughness measuring device after tape polishing using the polishing method according to the present embodiment. [Figure 6] FIG. 1 shows the results of measuring the surface roughness of a Bowden test piece, the surface of which is chrome-plated, by polishing with a polishing tape under specified polishing conditions and using a laser-type surface roughness measuring device. [Figure 7] 1 is a graph plotting the relationship between the load length ratio (tp) and the number of times the test piece reaches one point for test examples (B) and (D) to (G). [Figure 8] 1A and 1B are diagrams for explaining the relationship between a plateau shape and ride comfort. [Figure 9] FIG. 13 is a diagram for explaining an amplitude-dependent index. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention relates to a method for manufacturing a sliding member that repeats sliding motion (particularly reciprocating sliding motion) in the presence of lubricating oil, such as a piston rod used in a shock absorber of a vehicle. Conventionally, when manufacturing a sliding member, mechanical polishing has been performed on the surface of the sliding member in order to smooth the sliding motion of the sliding member. However, when the surface of the sliding member is mirror-finished, squeeze-out may occur, in which the lubricating oil interposed between the sliding member and the mating member leaks out due to the sliding motion. In this embodiment, a manufacturing method for a sliding member that can smooth the sliding motion of the sliding member and suppress the occurrence of squeeze-out will be described by taking a piston rod of a shock absorber as an example of a sliding member.

[0014] The method for manufacturing a piston rod according to this embodiment is characterized in that two-stage polishing is performed when mechanically polishing the outer circumferential surface of a cylindrical piston rod, and the piston rod can be manufactured by a known method otherwise. Specifically, the method is characterized in that the piston rod is polished in two stages in the circumferential direction of the piston rod with different types of polishing tapes by a tape polishing device 1 shown in FIG. 1, thereby manufacturing a piston rod having grooves that go around the circumferential direction of the piston rod and having a plateau-shaped surface cross section in the longitudinal direction as shown in FIG. 2. FIG. 1 is a configuration diagram showing the tape polishing device 1 according to this embodiment. FIG. 2 is a diagram in which the surface roughness of a piston rod polished by the polishing method according to this embodiment is visualized by measuring the surface roughness of the piston rod using a laser-type surface roughness measuring device.

[0015] First, a description will be given of a tape polishing device 1 according to this embodiment. As shown in Fig. 1, the tape polishing device 1 according to this embodiment has a feed motor 11 for feeding out the polishing tape T, a feed outlet 12 for the polishing tape T, a roller 13 for pressing the polishing tape T against the piston rod O, a take-up outlet 14 for the polishing tape T, and a take-up motor 15 for taking up the polishing tape.

[0016] In this embodiment, the piston rod O is set on the lathe 2, and the tape polishing device 1 is disposed on the side of the piston rod O. Then, by moving the roller 13 toward the piston rod O while rotating the piston rod O in the circumferential direction on the lathe 2, the polishing tape T wound around the roller 13 is brought into contact with the side surface of the piston rod O, and the piston rod O can be polished in the circumferential direction with the polishing tape T. The roller 13 is preferably made of an elastic resin such as urethane rubber. By making the roller 13 out of an elastic resin, the polishing tape T can be brought into contact with the piston rod O over a wide range. The hardness of the roller 13 is not particularly limited, but in this embodiment, a roller with a Shore A hardness of 90 or HS90 is used. However, the hardness of the roller 13 is not limited to this, and for example, a roller with a Shore A hardness of 30 to 70 or a roller with a Shore A hardness of HS30 to HS70 can be used. In addition, the roller 13 may be changed between the first polishing step and the second polishing step, in which case the hardness of the roller 13 used in the first polishing step may be made higher than that of the roller 13 used in the second polishing step.

[0017] In this embodiment, as described later, the piston rod O is polished with the polishing tape T while the polishing tape T is moved slowly in the longitudinal direction of the piston rod O, but in order to prevent the degree of polishing of the piston rod O from becoming uneven due to wear of the polishing surface of the polishing tape T, the polishing tape T is fed from the feed port 12 by the feed motor 11 while the polishing tape T is wound from the winding port 14 by the winding motor 15 as needed, thereby making it possible to polish the piston rod O uniformly. In particular, by making the feed speed of the polishing tape T faster than the moving speed of the polishing tape T in the longitudinal direction of the piston rod O, the piston rod O can be polished uniformly.

[0018] In this embodiment, the piston rod O is polished in two stages using two types of polishing tapes T1 and T2. Specifically, in the first stage of polishing, a first polishing step is performed in which the piston rod O is polished using a first polishing tape T1 having a grindstone with a larger average grain size than the second polishing tape T2 used in the second stage of polishing. The first polishing tape T1 is not particularly limited as long as the average grain size of the grindstone is larger than that of the second polishing tape T2, and for example, a polishing tape having a grindstone with an average grain size of 15 μm to 100 μm, more preferably a grindstone with an average grain size of 30 μm to 80 μm, and even more preferably a grindstone with an average grain size of 60 μm to 80 μm can be used. Also, the size of the grindstone may be defined by the "grain size" instead of the "average grain size" of the grindstone. In this case, the first abrasive tape T1 can be a tape having a grindstone with a smaller grit size than the second abrasive tape T2, for example, a tape having a grindstone with a grit size of 1000 to 120, more preferably a tape having a grindstone with a grit size of 400 to 150, can be used.

[0019] In the first polishing step, the piston rod O is polished in the circumferential direction using the first polishing tape T1, so that a groove that goes around the piston rod O in the circumferential direction is formed in the piston rod O as shown in FIG. 2. In the first polishing step, the rotation speed of the piston rod O is not particularly limited, but may be, for example, 1000 to 3000 rpm. On the other hand, the feed speed of the first polishing tape T1 is set to a speed slower than the rotation speed of the piston rod O, and is preferably set to a speed of 1 / 10 or less of the rotation speed of the piston rod O, and more preferably set to a speed of 1 / 100 or less of the rotation speed of the piston rod O. If the feed speed of the first polishing tape T1 is set to be approximately the same as the rotation speed of the piston rod O, the position of the grindstone (position in the longitudinal direction) may change before the piston rod O makes one rotation, and it may not be possible to form a groove that goes around the piston rod O in the circumferential direction as shown in FIG. 2. Therefore, by setting the feed speed of the first abrasive tape T1 to a speed slower than the rotation speed of the piston rod O, it is possible to form a groove that goes around the piston rod O in the circumferential direction, as shown in FIG.

[0020] Furthermore, in the first polishing step, the speed at which the first polishing tape T1 is moved in the longitudinal direction of the piston rod O is set to 1 / 100 or less, more preferably 1 / 1000 or less, of the rotation speed of the piston rod O. In addition, in the first polishing step, oscillation (swinging) of moving the first polishing tape 1T back and forth in the longitudinal direction of the piston rod O to smooth the polished surface is not performed. In this way, by performing the first polishing step, it is possible to form a groove that goes around in the circumferential direction as shown in FIG. 2 or FIG. 3(B) on the piston rod O, instead of a helical (diagonal) groove as shown in FIG. 3(A), and it is possible to suppress the occurrence of squeeze-out. That is, when a helical groove is formed on the piston rod as shown in FIG. 3(A) or when the piston rod is mirror-finished, the lubricating oil may leak out between the sliding members (or to the outside of the oil pool) by running down the helical groove or moving along the mirror-finished surface. On the other hand, as shown in FIG. 2 or 3(B), by forming a groove going around the piston rod O in the circumferential direction, the lubricating oil can be retained in the groove going around the piston rod O in the circumferential direction, and the lubricating oil can be retained between the sliding members (or in an oil pool). In the above-mentioned example, the first polishing tape T1 is moved in the longitudinal direction of the piston rod O, but the present invention is not limited to this. The piston rod O may be moved in the longitudinal direction of the piston rod O while the position of the first polishing tape T1 is fixed. In this case, too, it is preferable to set the relative movement speed between the first polishing tape T1 and the piston rod O in the longitudinal direction of the piston rod O to 1 / 100 or less, more preferably 1 / 1000 or less, of the rotation speed of the piston rod O.

[0021] In the second polishing step, the piston rod O is polished using the second polishing tape T2. The second polishing tape T2 is a polishing tape having an abrasive having a smaller average grain size than the first polishing tape T1. The second polishing tape T2 is also not particularly limited as long as the average grain size of the abrasive is smaller than that of the first polishing tape T1, and for example, a polishing tape having an abrasive having an average grain size of 0.1 μm to 12 μm can be used. Similarly to the first polishing tape T1, the size of the abrasive of the second polishing tape T2 can also be defined by the grain size. In this case, the second polishing tape T2 can be a tape having an abrasive having a larger grain size than the first polishing tape T1, and for example, a tape having an abrasive having a grain size of 20000 to 1500 can be used. In the present invention, the "average grain size" and "grain size" of the first polishing tape T1 and the second polishing tape T2 can be the "average grain size" and "grain size" specified for commercially available polishing tapes.

[0022] In the second polishing step, the piston rod O is polished using the second polishing tape T2 having an abrasive having a smaller average grain size than the first polishing tape T1, so that the surface cross section of the piston rod O in the longitudinal direction can be formed into a plateau shape (trapezoidal shape) as shown in FIG. 4(B). Here, FIG. 4 is a schematic diagram for explaining the surface cross section of the piston rod in the longitudinal direction according to this embodiment, FIG. 4(A) is a schematic diagram showing the surface cross section of the piston rod in the longitudinal direction after the first polishing step polished with the first polishing tape T1, and FIG. 4(B) is a schematic diagram showing the surface cross section of the piston rod in the longitudinal direction after the second polishing step polished with the second polishing tape T2. As shown in FIG. 4(A), in the first polishing step, the piston rod O is polished in the circumferential direction using the first polishing tape T1 having an abrasive having a larger average grain size, so that mountain-shaped unevenness (unevenness with a sharp tip) is formed in the longitudinal direction of the piston rod O. In the second polishing step, the piston rod is polished with the second polishing tape T2, and since the average grain size of the grindstone of the second polishing tape T2 is smaller than that of the first polishing tape T1, the peaks S on the surface of the piston rod O after the first polishing step can be polished, and as a result, as shown in Fig. 4(B), the peaks S on the surface of the piston rod are scraped off, and the surface cross section in the longitudinal direction is formed into a plateau shape (trapezoidal shape). Note that R1 in Fig. 4(A) is the part of the piston rod before the first polishing step, and R2 in Fig. 4(B) is the part of the piston rod after the first polishing step and before the second polishing step.

[0023] In the second polishing process, unlike the first polishing process, a groove that goes around in the circumferential direction is not formed, so that the second polishing tape T2 is not polished in the circumferential direction of the piston rod O as in the first polishing process, but rather, for example, the piston rod O is oscillated in the longitudinal direction and polished in the longitudinal direction of the piston rod. On the other hand, in the second polishing process, similar to the first polishing process, the piston rod O can be polished in the circumferential direction of the piston rod O using the second polishing tape T2. Also, in the second polishing process, the second polishing tape T2 may be moved in the longitudinal direction of the piston rod O, or the piston rod O may be moved in the longitudinal direction of the piston rod O while the position of the second polishing tape T2 is fixed. In this case, the relative movement speed between the second polishing tape T2 and the piston rod O in the longitudinal direction of the piston rod O is preferably set to 1 / 100 or less, more preferably 1 / 1000 or less, of the rotation speed of the piston rod O.

[0024] In the second polishing step, polishing is performed using a polishing tape in the same manner as in the first polishing step, and the following effect can be achieved. That is, even if "waviness" occurs on the polished surface of the piston rod O in the first polishing step, in the second polishing step, the second polishing tape T2 is pressed against the piston rod O polished in the first polishing step by the roller 13, which is a rubber roller, so that the second polishing tape T2 changes its shape to match the "waviness" and can polish the piston rod O, thereby making it possible to uniformly polish the piston rod O with the second polishing tape T2.

[0025] In addition, the second polishing step can be configured to perform polishing without using a polishing tape as long as the method can change the mountain-shaped unevenness shown in Fig. 4(A) to the plateau-shaped unevenness shown in Fig. 4(B). In this case, polishing can be performed using an elastic grindstone such as rubber or sponge, or buff polishing can be performed using an abrasive cloth.

[0026] In this embodiment, after the first polishing step is completed, the first polishing tape T1 is removed from the tape polishing device 10, and the second polishing tape T2 is attached to the tape polishing device 10, thereby executing the second polishing step. However, the present invention is not limited to the above method, and for example, two tape polishing devices 10, one with the first polishing tape T1 attached and the other with the second polishing tape T2 attached, may be arranged side by side, and the piston rod O may be polished by the tape polishing device 10 with the first polishing tape T1 attached, and then successively polished by the tape polishing device 10 with the second polishing tape T2 attached.

[0027] Next, an embodiment of the present invention will be described. FIG. 5 shows the result of measuring the surface roughness of a piston rod of a shock absorber by tape polishing using the polishing method according to this embodiment and using a laser type surface roughness measuring device. For example, in the example shown in FIG. 5(a), a first polishing step is performed using a first polishing tape T1 having an average grain size of 60 μm, and then a second polishing step is performed using a second polishing tape T2 having an average grain size of 3 μm at a polishing speed of 4.4 mm / s and a polishing pressure of 0.26 MPa. The above-mentioned "polishing speed" refers to the speed at which the second polishing tape T2 is moved in the longitudinal direction of the piston rod, and the faster the polishing speed, the faster the polishing position of the piston rod changes, and the fewer the number of times the piston rod O is polished at the same position. Similarly, in the examples shown in Fig. 5(b) to (e), the first polishing step was performed using the first polishing tape T1 with an average grain size of 60 µm or 30 µm, and then the second polishing tape T2 with an average grain size of 3 µm was used to perform tape polishing at a polishing speed of 4.4 mm / s or 8.8 mm / s and a polishing pressure of 0.26 Mpa or 0.15 Mpa. From the surface roughness measurement results shown in Fig. 5, it was found that the surface cross section in the longitudinal direction can be formed into a plateau shape as shown in Fig. 4(B) by performing the second polishing step using the second polishing tape T2 after the first polishing step using the first polishing tape T1. It was also found that the plateau shape of the polished surface of the sliding member (for example, the depth of the groove, the size of the flat part, the load length ratio (tp), etc.) can be changed by changing the size of the grindstone of the first polishing tape T1 and the polishing speed and polishing pressure in the second polishing step.

[0028] Further, FIG. 6 shows the results of measuring the surface roughness of a chrome-plated Bowden test piece by polishing it with a polishing tape under the polishing conditions shown below, and using a laser-type surface roughness measuring device. That is, the example shown in FIG. 6(A) is an example in which only the first polishing step was performed using a first polishing tape T1 with an average grain size of 60 μm, and the example shown in FIG. 6(B) is an example in which the first polishing step was performed using a first polishing tape T1 with an average grain size of 60 μm, and then the second polishing step was performed using a second polishing tape T2 with an average grain size of 3 μm. Also, the example shown in FIG. 6(C) is an example in which only the first polishing step was performed using a first polishing tape T1 with an average grain size of 30 μm, and the example shown in FIG. 6(D) is an example in which the first polishing step was performed using a first polishing tape T1 with an average grain size of 30 μm, and then the second polishing step was performed using a second polishing tape T2 with an average grain size of 3 μm. Furthermore, FIG. 6(E) shows an example of mirror finishing using an abrasive tape with an average particle size of 1 μm, and FIG. 6(F) shows an example of random polishing not only in the circumferential direction but also in the longitudinal direction and in the oblique direction. In the examples shown in FIG. 6(A) to (F), the polishing speed and polishing pressure were the same. In the example shown in FIG. 6, as in the example shown in FIG. 5, the first polishing step using the first polishing tape T1 alone results in a mountain-shaped surface cross section in the longitudinal direction as shown in FIG. 4(A), whereas the second polishing step using the second polishing tape T2 after the first polishing step can form a plateau-shaped surface cross section in the longitudinal direction as shown in FIG. 4(B). In addition, in FIG. 6(A) to (D), it can be seen that grooves are formed around the circumferential direction, but in FIG. 6(F), it can be seen that grooves are formed in the oblique direction (spiral shape).

[0029] Furthermore, the load length ratio (tp) and the number of times of reaching one point defined in JIS B0601:1994 were measured for the test examples shown in Fig. 6(B), (D) to (F) and the test example (G) in which the first polishing step was performed using the first polishing tape T1 with an average grain size of 80 μm and then the second polishing step was performed using the second polishing tape T2 with an average grain size of 3 μm. Fig. 7 is a graph plotting the relationship between the load length ratio (tp) (unit: %) and the number of times of reaching one point (unit: 10,000 times) for the test examples (B), (D) to (F), and (G). The number of times of reaching one point indicates how many tens of thousands of sliding operations were performed before the lubricating oil leaked out between the sliding members. As shown in Fig. 7, the test example (E) with a mirror finish had the lowest load length ratio (tp) of about 0%, and the number of times of reaching one point was also low at about 1 million times. In addition, in test example (D), in which a first polishing process was performed using a first polishing tape T1 having a grinding wheel with an average grain size of 30 μm, and then a second polishing process was performed using a second polishing tape T2 having a grinding wheel with a grain size of 3 μm, the load length ratio (tp) was just under 20%, but the number of times the single point was reached was low at about 1 million times, similar to test example (E), in which mirror finishing was performed.

[0030] On the other hand, in the test example (G) in which the first polishing process was performed with the first polishing tape T1 having an 80 μm grindstone and then the second polishing process was performed with the second polishing tape T2 having a 3 μm grindstone, the load length ratio (tp) was about 60%, and the number of times of reaching one point was high at about 10 million times. Similarly, in the test example (B) in which the first polishing process was performed with the first polishing tape T1 having a 60 μm grindstone and then the second polishing process was performed with the second polishing tape T2 having a 3 μm grindstone, the load length ratio (tp) was about 70%, and the number of times of reaching one point was also high at about 10 million times. In this way, it was found that there is a certain correlation between the load length ratio (tp) of the sliding member and the number of times of reaching one point, and it was found that the number of times of reaching one point tends to increase as the load length ratio (tp) increases. In addition, in test example (F), where grinding was performed in both the longitudinal and diagonal directions, the load length ratio (tp) was nearly 100% higher, but the number of times it reached one point was about the same as test examples (G) and (B). This is thought to be because in test example (F), grooves were formed in both the longitudinal and diagonal directions, so even though the load length ratio (tp) was high, lubricating oil was likely to leak through the grooves.

[0031] Furthermore, the influence on the ride comfort of the vehicle was examined by polishing the piston rod of a shock absorber for a vehicle by the polishing method according to this embodiment. Specifically, as shown in Fig. 8(A) to (C), in the polishing method according to this embodiment, the average grain size of the grindstone of the first polishing tape T1, the average grain size of the grindstone of the second polishing tape T2, the polishing speed, polishing pressure, polishing time, etc. of the first polishing step and the second polishing step were changed, and the change in ride comfort was measured when the plateau shape of the surface cross section of the piston rod, such as the load length ratio (tp), was changed. In this embodiment, as shown in Fig. 9, when the friction coefficient at the time of the fine amplitude is μ2 and the friction coefficient at the time of the normal amplitude is μ1, the amplitude-dependent index, which is the ratio (μ2 / μ1) of the friction coefficient μ1 at the time of the normal amplitude to the friction coefficient μ2 at the fine amplitude, was used as an index indicating the ride comfort. As a result, it was found that the ride comfort can be changed by changing the average grain size of the grindstone of the first polishing tape T1, the average grain size of the grindstone of the second polishing tape T2, the polishing speed, polishing pressure, polishing time, etc. in the first and second polishing steps, and by adjusting the shape of the surface cross section in the longitudinal direction of the piston rod (for example, by adjusting the depth of the grooves in the plateau shape, the angle of inclination, the cross-sectional length ratio, etc.) as shown in Figures 8(A) to (C). In particular, it was found that the load length ratio (tp) in the longitudinal direction of the piston rod has a large effect on the ride comfort. Specifically, it was found that the higher the load length ratio (tp), the higher the tendency for the ride comfort to be.

[0032] As described above, in the manufacturing method of the piston rod (sliding member) according to the present embodiment, a first polishing step is performed in which the surface of the piston rod is polished in the circumferential direction of the piston rod using a first polishing tape T1 having a first grindstone, and a second polishing step is performed in which the piston rod polished in the first polishing step is polished in the circumferential direction of the piston rod using a second polishing tape T2 having a second grindstone having an average grain size smaller than that of the first polishing tape T1. This makes it possible to manufacture a piston rod having grooves running in the circumferential direction on the surface of the piston rod and having a surface cross section in the longitudinal direction of the piston rod formed in a plateau shape. In this way, in the piston rod having grooves running in the circumferential direction on the surface and having a surface cross section in the longitudinal direction formed in a plateau shape, the mountain-shaped unevenness is polished to have a plateau shape, so that the piston rod is less likely to get caught by the unevenness of the mating member, and can perform a smooth sliding operation, and even when the piston rod slides, the lubricating oil remains in the grooves running in the circumferential direction, so that the occurrence of squeeze-out, in which the lubricating oil leaks out between the sliding members, can be suppressed. Furthermore, in this embodiment, by setting the average grain size of the first grindstone to 15 to 100 μm and the average grain size of the second grindstone to 0.1 to 12 μm, it was possible to suppress squeeze-out of the lubricant until the number of times of reaching one point reached approximately 10 million times.

[0033] Furthermore, in this embodiment, in the first polishing process, the feed speed of the first polishing tape T1 is set to 1 / 10 or less of the rotation speed of the piston rod, and the relative movement speed of the first polishing tape T1 in the longitudinal direction of the piston rod is set to 1 / 100 or less of the rotation speed of the piston rod. Furthermore, by not performing oscillation to move the first polishing tape T1 back and forth in the longitudinal direction of the piston rod, it is possible to appropriately form a groove running around the circumference of the surface of the piston rod as shown in Figure 2, and it is also possible to set the load length ratio (tp) in the longitudinal direction to 50% or more.

[0034] It was also found that when polishing a piston rod with the polishing method according to the present embodiment, the ride comfort of a moving body using a shock absorber having the piston rod can be adjusted by adjusting the load length ratio (tp) in the longitudinal direction of the piston rod. Therefore, it is expected that in the future, it will be possible to appropriately adjust the ride comfort of a shock absorber by polishing the piston rod (or the shape of the piston rod surface).

[0035] Although the preferred embodiment of the present invention has been described above, the technical scope of the present invention is not limited to the description of the above embodiment. Various modifications and improvements can be made to the above embodiment, and such modifications and improvements are also included in the technical scope of the present invention.

[0036] For example, in the above-mentioned embodiment, a piston rod used in a shock absorber is exemplified as a sliding member, but the sliding member according to the present invention is not limited to the piston rod of a shock absorber as long as it is a member that performs a sliding operation in the presence of lubricating oil, and the present invention can be applied to various parts that perform a sliding operation, such as pistons and actuator parts of hydraulic pumps and hydraulic motors. Furthermore, the "lubricating oil" according to the present invention does not only have the function of lubricating the sliding operation of a sliding member, but can also include oil that has the function of transmitting power, such as hydraulic oil for hydraulic equipment.

[0037] The "polishing tape" according to the present invention may also include polishing films that are commercially available. The polishing tape according to the present invention may be either a wrapping tape or a finishing tape, but it is preferable to use a finishing tape as the first polishing tape T1 and a wrapping tape as the second polishing tape. [Explanation of symbols]

[0038] 1...Tape polishing device 11...Feed motor 12…Outlet 13…Roller 14…Winding opening 15…Winding motor 2. Lathe T: Polishing tape T1…First polishing tape T2: Second abrasive tape O…Piston rod

Claims

1. A method for manufacturing a shock absorber sliding member that performs a sliding operation in the presence of a lubricating oil, comprising the steps of: The shock absorber sliding member is a cylindrical rod, a first polishing step of polishing an outer peripheral surface of the rod in a circumferential direction of the rod using a polishing tape having a first grindstone to form a plurality of grooves around the rod in the circumferential direction; a second polishing step of polishing the rod after the first polishing step to form an outer circumferential surface cross section in a longitudinal direction of the rod into a plateau shape; In the first polishing step, the polishing tape is fed out while rotating the rod, and the polishing tape is brought into contact with the rod to polish it, and a feed speed of the polishing tape is 1 / 10 or less relative to a rotation speed of the rod.

2. 2. The method for manufacturing a shock absorber sliding member according to claim 1, wherein the first grindstone has an average grain size of 15 to 100 μm.

3. 3. The method for manufacturing a shock absorber sliding member according to claim 1, wherein the second polishing step polishes the rod in a circumferential direction by using a polishing tape having a second grindstone having an average grain size smaller than that of the first grindstone.

4. 4. The method for producing a shock absorber sliding member according to claim 3, wherein the second grindstone has an average grain size of 0.1 to 12 μm.

5. 5. The method for manufacturing a shock absorber sliding member according to claim 1, wherein in the first polishing step, the polishing tape is fed out while rotating the rod, and the polishing tape is brought into contact with the rod for polishing, and a relative movement speed between the rod and the polishing tape in the longitudinal direction of the rod is 1 / 100 or less of a rotation speed of the rod.

6. 6. The method for manufacturing a shock absorber sliding member according to claim 1, wherein in the first polishing step, oscillation in which the polishing tape is reciprocated in the longitudinal direction of the rod is not performed.

7. 7. A method for manufacturing a shock absorber, comprising the steps of: manufacturing a shock absorber sliding member of a shock absorber by using the method for manufacturing a shock absorber sliding member according to claim 1.

8. 7. The method for manufacturing a shock absorber sliding member according to claim 1, wherein, when polishing the shock absorber sliding member used in a shock absorber of a moving body, the shock absorber sliding member is polished so that an outer peripheral surface cross section in the longitudinal direction has a plateau shape, and a load length ratio (tp) in the longitudinal direction is adjusted in order to adjust a ride comfort of the moving body using the shock absorber.

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