JP2014018908A - Surface treatment method for moving body of cylindrical type hydraulic device, and cylindrical type hydraulic device with the moving body subjected to the surface treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface treatment method for treating an outer circumferential surface of a moving body constituting a cylindrical type hydraulic device using spray coating of tungsten, the surface treatment method capable of expressing a sealing performance required, and to provide the cylindrical type hydraulic device with the moving body subjected to the surface treatment.SOLUTION: A surface treatment method sequentially includes: a film formation step of forming a sprayed coating surface D including tungsten by a spraying method on an outer circumferential surface coming into slide contact with at least a sealing member of a moving body 3a; a first polishing step of polishing the sprayed coating surface D by bringing a polishing tool T into abutment with the sprayed coating surface D of the moving body 3a, and also by applying a composite movement of an oscillating movement C for reciprocating the tool by a predetermined distance along a central axis direction of the moving body 3a, and a traverse movement B for reciprocating the tool over the entire area of the sprayed coating surface D similarly along the central axis direction of the moving body 3a, to the polishing tool T; and a second polishing step of polishing the sprayed coating surface D finishing the first polishing step by providing only the traverse movement B to the polishing tool T.

Description

  TECHNICAL FIELD The present invention relates to a surface treatment method for a moving body in a cylindrical hydraulic / pneumatic device, and a cylindrical hydraulic / pneumatic device including a moving body subjected to this surface treatment.

  Conventionally, as a cylindrical hydraulic / pneumatic device, a cylindrical body having an internal space, a moving body inserted into the internal space of the cylindrical body, and a seal member disposed between the cylindrical body and the moving body, As one specific device related to such a cylindrical hydraulic / pneumatic device, for example, an aircraft leg device can be cited. An example of this leg device is shown in FIGS. FIG. 9 is a front sectional view showing main components of the leg device, and FIG. 10 is an enlarged view showing an E portion of FIG.

  As shown in FIGS. 9 and 10, the leg device 1 includes an outer cylinder 2 having an inner space, an inner cylinder 3 that is movably inserted in the inner space of the outer cylinder 2 in the axial direction, An upper cam cylinder 4 that is fixed to the inner cylinder 3 and moves together with the inner cylinder 3 in the inner space of the outer cylinder 2, a lower cam cylinder 5 that is fitted to the inner peripheral surface of the outer cylinder 2, and the outer cylinder The seal members 6a and 6b for preventing leakage of the fluid filled in the internal space of the tube 2 and the inner peripheral surface of the outer tube 2 and the outer peripheral surface of the inner tube 3, And a lower bearing 7 for holding the members 6a and 6b. The upper end of the outer cylinder 2 is connected to the aircraft body, and the wheel 8 is attached to the lower end of the inner cylinder 3. The inner cylinder 3 includes an inner cylinder body 3 a and an upper bearing 3 b that directly contacts the inner peripheral surface of the outer cylinder 2. Of the two sealing members 6a and 6b, one sealing member 6a is interposed between the inner cylinder body 3a and the other sealing member 6b is interposed between the outer cylinder 2 and the other sealing member 6a. .

  In the leg device 1, the inner cylinder 3 and the upper cam cylinder 4 contract by moving upward in the inner space of the outer cylinder 2, and the inner cylinder 3 and the upper cam cylinder 4 move in the inner space of the outer cylinder 2. It is configured to extend by moving downward. That is, the aircraft contracts while the aircraft is traveling on the ground and expands when the aircraft takes off.

  By the way, since the outer peripheral surface of the inner cylinder main body 3a is in sliding contact with the seal member 6a during the movement in the vertical direction, the outer peripheral surface has wear resistance due to a problem on the seal. It has been required to have high accuracy with respect to the surface roughness. For this reason, conventionally, a method has been generally employed in which the outer peripheral surface of the inner cylinder main body 3a is subjected to chrome plating, and then the plated portion is mirror-finished.

  However, recently, regarding chrome plating, environmental problems have been pointed out. Therefore, as disclosed in Japanese Patent No. 4307196, a thermal spray coating containing tungsten is formed on the surface to be treated by a so-called thermal spraying method. However, surface treatment methods have been studied in which the formed sprayed coating is mirror-finished.

  Examples of the thermal spray coating containing tungsten include tungsten carbide (WC) and a mixture of tungsten carbide and chrome carbide.

Japanese Patent No. 4307196

  From the background as described above, the inventors of the present invention diligently studied to apply the surface treatment method using the thermal spray coating to the surface treatment of the outer peripheral surface of the inner cylinder main body 3a. And first, in order to finish the surface roughness of the sprayed coating surface having high hardness with high accuracy, a grindstone provided with at least one of diamond particles and cubic boron nitride particles is used as an abrasive grain. The grindstone is brought into contact with the sprayed coating surface formed on the outer peripheral surface of the inner cylinder main body 3a rotated about the axis, and reciprocated by a predetermined distance along the central axis direction of the inner cylinder main body 3a. The sprayed coating was polished by applying to the grindstone a combined operation of a vibrating operation to be performed and a traverse operation in which the entire sprayed coating was reciprocated along the central axis direction.

  In this way, by giving the grindstone a combined operation of vibration operation and traverse operation, the grinding action of the grindstone on the surface of the sprayed coating can be enhanced, and the feed line of the grindstone is transferred to the surface of the sprayed coating. Therefore, the surface roughness can be finished with higher accuracy than required for sealing performance.

  However, even when the surface roughness of the thermal spray coating is finished with a higher precision than required for sealing performance, if the inner cylinder body 3a is repeatedly expanded and contracted, the inner space of the outer cylinder 2 is filled. This causes a problem that the fluid that is leaked from the sliding contact portion between the inner cylinder main body 3a and the seal member 6a.

  Therefore, as a result of further investigations to investigate the cause of the present inventors, by repeatedly expanding and contracting the inner cylinder main body 3a, the shavings of the seal member adhere to the outer peripheral surface of the inner cylinder main body 3a, We have obtained the knowledge that the sealing performance deteriorates due to the attached shavings and the fluid leaks. Further, the sticking of shavings on the sealing member is a so-called cross hatch pattern formed on the thermal spray coating by polishing. It came to the knowledge that it was caused by (polishing mark formed by abrasive grains).

  The present invention has been made in view of the above circumstances, and an object thereof is a surface treatment method for treating the outer peripheral surface of a moving body constituting a cylindrical hydraulic / pneumatic device using thermal spraying of tungsten. The present invention provides a surface treatment method capable of exhibiting a sealing performance and a cylindrical hydraulic / pneumatic device including a moving body subjected to the surface treatment.

The present invention for solving the above problems is as follows.
A cylindrical body having an internal space; a cylindrical or rod-shaped movable body that is movably inserted in the internal space of the cylindrical body; and an inner peripheral surface of the cylindrical body and an outer peripheral surface of the movable body The movement in a cylindrical hydraulic / pneumatic apparatus provided with a seal member disposed between and in sliding contact with the outer peripheral surface of the movable body to prevent leakage of a fluid filled in the internal space of the tubular body The present invention relates to a method for surface treatment of the outer peripheral surface of a body.

And this surface treatment method is
A coating forming step of forming a thermal spray coating containing tungsten by a thermal spraying method on at least an outer peripheral surface of the movable body that is in sliding contact with the seal member;
In a state where the movable body is rotated about the axis, a polishing working surface of a polishing tool provided with at least one of diamond particles and cubic boron nitride particles as abrasive grains is brought into contact with the sprayed coating surface of the movable body. A combined operation of a vibration operation that reciprocates a predetermined distance along the central axis direction of the moving body and a traverse operation that reciprocates the entire area of the sprayed coating along the central axis direction of the moving body. A first polishing step for applying to the polishing tool and polishing the sprayed coating surface;
The polishing surface of the polishing tool is brought into contact with the sprayed coating surface of the moving body while the moving body is rotated about the axis, and only the traverse operation is applied to the polishing tool, and the first polishing step A second polishing step of polishing the sprayed coating surface finished
The film forming step, the first polishing step, and the second polishing step are sequentially performed.

  In this surface treatment method, as described above, first, in the coating forming step, a sprayed coating containing tungsten is formed by a spraying method on at least the outer peripheral surface of the movable body that is in sliding contact with the seal member. The film thickness of the sprayed coating to be formed is appropriately set as necessary, but is generally 0.076 to 0.3 mm.

  Next, in the first polishing step, with the moving body rotated about the axis, the polishing working surface of the polishing tool is brought into contact with the sprayed coating surface of the moving body, and the vibration operation and the traverse operation are performed. A composite operation is applied to the polishing tool to polish the sprayed coating surface. In this way, by providing the polishing tool with a combined operation of vibration operation and traverse operation, the polishing action of the polishing tool on the surface of the sprayed coating can be enhanced, and the feed line of the polishing tool is set on the surface of the sprayed coating. It is possible to prevent transfer, that is, it is possible to prevent the occurrence of polishing marks on the sprayed coating surface due to the traverse operation, so that the surface roughness is higher than required for sealing performance. It can be finished with precision.

  The moving distance in the vibration operation is a very small distance that is very shorter than the moving distance in the traverse operation.

  Next, the second polishing step is performed on the sprayed coating surface of the moving body after the surface roughness is finished with high accuracy by the first polishing step. In the second polishing step, as described above, only the traverse operation is given to the grindstone.

  In the first polishing step, since the vibration operation is imparted to the polishing tool, the polishing action is high. As a result, the surface roughness obtained is highly accurate, but on the other hand, the object to be polished is obtained. On the surface, a cross hatch pattern (polishing mark formed by abrasive grains) is formed along with the vibration operation. As described above, this cross-hatch pattern causes the shavings of the sealing member to adhere to the outer peripheral surface of the moving body due to the movement of the moving body in the axial direction, and causes the sealability to deteriorate due to the attached shavings. It is.

  Therefore, the sprayed coating surface of the moving body after the surface roughness is finished with high accuracy by the first polishing step is polished by only the traverse operation without the vibration operation in the second polishing step. Thus, the cross hatch pattern formed in the first polishing step can be erased while maintaining the surface roughness with high accuracy.

  Thus, by performing the second polishing step after the first polishing step, it is possible to finish the sprayed coating surface of the moving body with a highly accurate surface roughness and a polished surface having no cross hatch pattern. it can. Therefore, there is no leakage of fluid due to the cross hatch pattern, which has been a problem in the past.

The present invention also includes a cylinder having an internal space,
A cylindrical or rod-like moving body that is inserted into the inner space of the cylindrical body so as to be movable in the axial direction of the cylindrical body,
It is disposed between the inner peripheral surface of the cylindrical body and the outer peripheral surface of the movable body and is in sliding contact with the outer peripheral surface of the movable body to prevent leakage of the fluid filled in the internal space of the cylindrical body. A cylindrical hydraulic / pneumatic device including a seal member,
The movable body relates to a cylindrical hydraulic / pneumatic device in which at least an outer peripheral surface in sliding contact with the seal member is processed by the surface treatment method.

  According to this cylindrical hydraulic / pneumatic apparatus, the sprayed coating surface formed on at least the outer peripheral surface that is in sliding contact with the sealing member of the moving body is polished with a high surface roughness and no cross-hatch pattern. Can be finished. Therefore, there is no fluid leakage caused by the cross hatch pattern, which has been a problem in the past.

  In the second polishing step, it is preferable to rotate the movable body so that the peripheral speed of the outer peripheral surface is 11 m / min or more. In this way, the surface roughness of the sprayed coating surface can be finished with higher accuracy, and the shavings of the seal member can be more effectively prevented from adhering to the outer peripheral surface of the moving body.

  As described in detail above, according to the present invention, after performing the first polishing step in which the combined operation of the vibration operation and the traverse operation is applied to the grindstone, the second polishing step in which only the traverse operation is applied to the grindstone is performed. As a result, the sprayed coating surface of the moving body can be finished with high surface roughness and a polished surface without a cross-hatch pattern. Therefore, there is no leakage of fluid due to the cross hatch pattern, which has been a problem in the past.

It is explanatory drawing for demonstrating the procedure of the surface treatment method which concerns on one actual form of this invention. It is explanatory drawing for demonstrating the procedure of the surface treatment method which concerns on one actual form of this invention. It is explanatory drawing for demonstrating the procedure of the surface treatment method which concerns on one actual form of this invention. It is a table | surface which shows the result of having measured the surface roughness of the inner cylinder main body which concerns on Examples 1, 2 and Comparative Examples 1,2. 2 is a photograph showing the outer peripheral surface (sprayed coating surface) of the inner cylinder main body according to Example 1; 6 is a photograph showing the outer peripheral surface (sprayed coating surface) of an inner cylinder main body according to Example 2. FIG. 4 is a photograph showing an outer peripheral surface (sprayed coating surface) of an inner cylinder main body according to Comparative Example 1. FIG. 6 is a photograph showing an outer peripheral surface (sprayed coating surface) of an inner cylinder main body according to Comparative Example 2. It is the front sectional view which showed the main components of the conventional aircraft leg apparatus. It is the enlarged view to which the E section in FIG. 9 was expanded.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

  The cylindrical hydraulic / pneumatic device according to the present embodiment is the aircraft leg device 1 shown in FIGS. 9 and 10 described above, and surface treatment is performed on the outer peripheral surface of the inner cylinder main body 3a. In addition, since the specific structure of the leg apparatus 1 is as above-mentioned, the detailed description is abbreviate | omitted.

  The surface treatment method according to the present embodiment includes a coating forming process for forming a sprayed coating on the outer peripheral surface of the inner cylinder main body 3a, and a first polishing process and a second polishing process for polishing the formed sprayed coating. A polishing step is performed. Hereinafter, each step will be described.

A. Film Forming Process In the film forming process, a sprayed film is formed on the outer peripheral surface of the inner cylinder body 3a by a high-speed flame spraying method using tungsten carbide powder in a state where the inner cylinder body 3a is rotated about the axis. . High-speed flame spraying is a method in which powder material is sprayed using high-pressure gas mixed with propylene, hydrogen, etc. and oxygen as fuel, and since the flame is formed so that the ignition gas wraps the powder material, the powder is uniform. The film is accelerated while being heated to form a high-quality film on the surface of the object. The spraying method is not limited to the high-speed flame spraying method, and a sprayed coating may be formed by another spraying method. The thickness of the sprayed coating formed in this coating forming process is approximately 0.076 to 0.3 mm.

B. Polishing Step Next, the thermal spray coating surface formed on the outer peripheral surface of the inner cylinder body 3a is subjected to polishing using the polishing apparatus 10 shown in FIG.

[Polishing equipment]
A polishing apparatus 10 shown in FIG. 1 has the same basic configuration as an apparatus called a so-called cylindrical grinder, and includes a spindle 11 on which a chuck 12 for holding an inner cylinder body 3a as a workpiece is mounted, and the chuck 12 and a grinding wheel base 14 for supporting the polishing tool T.

  The main shaft 11 is rotatably supported by a main shaft (not shown), and the core pushing table 13 is movable in a direction to advance and retreat with respect to the chuck 12.

  The grindstone table 14 is appropriately driven by a feeding device (not shown), and is movable in the axial direction of the main shaft 11 and in a direction perpendicular to the main axis 11, and further in the axial direction of the main shaft 11. A traverse operation that reciprocates along a predetermined stroke along the direction indicated by the arrow B in FIGS. 2 and 3 is applied. Note that the stroke of the traverse operation can be set according to the polishing range of the object to be polished, and is set to a stroke that can trace the required polishing range.

  The polishing tool T held on the grinding wheel base 14 is set within a predetermined minute distance (for example, in the range of 1 to 5 mm) along the axial direction of the main shaft 11 by an appropriate vibration applying device (not shown). A vibration operation (operation in the direction indicated by arrow C shown in FIGS. 1 and 2) that reciprocates by a distance is provided.

  The polishing tool T is a grindstone having a substantially rectangular parallelepiped shape, and is a diamond grindstone in which diamond particles as abrasive grains are fixed to the polishing surface Ta. The abrasive grains are not limited to diamond particles, but may be cubic boron nitride particles. Further, the polishing tool T is not in the form of the above-described grindstone, but instead may be in the form of a film in which the abrasive grains are uniformly applied and fixed on the surface. In this case, the film is formed in a roll shape, and the abrasive grain fixing surface is brought into contact with the object to be polished while the film is successively drawn out.

  The following 1st grinding | polishing process and 2nd grinding | polishing process are implemented with respect to the sprayed coating surface formed in the outer peripheral surface of the inner cylinder main body 3a using the grinding | polishing apparatus 10 provided with the above structure.

[First polishing step]
In the first polishing step, first, the inner cylinder body 3a is held by the chuck 12 and the core push stand 13 so that the axis thereof is coaxial with the axis of the main shaft 11, and then the main shaft 11 is rotated around the axis. . The rotational speed of the main shaft 11 can be set as appropriate, but it is preferable to set the rotational speed so that the peripheral speed of the outer peripheral surface of the inner cylinder main body 3a is 11 m / min or more.

  Next, as shown in FIG. 1, the grindstone base 14 is moved in the direction indicated by the arrow A toward the inner cylinder main body 3a, and the polishing action surface Ta of the polishing tool T is changed to the thermal spray coating surface of the inner cylinder main body 3a (see FIG. 1, the abutting operation is performed on the polishing tool T, and the polishing tool T is vibrated in a direction parallel to the central axis direction of the inner cylinder main body 3a.

  Next, as shown in FIG. 2, the grinding wheel base 14 is reciprocated in the direction indicated by the arrow B, and a traverse operation is imparted to the polishing tool T. Thereby, the polishing tool T is given a composite operation in which the vibration operation and the traverse operation are combined, and the thermal spray coating surface D of the inner cylinder main body 3a is polished by the composite operation.

  In this way, by giving the polishing tool T a combined operation of the vibration operation and the traverse operation, the polishing action of the polishing tool T on the sprayed coating surface D can be enhanced, and the feed line of the polishing tool T can be improved. It is possible to prevent transfer to the thermal spray coating surface D, that is, it is possible to prevent the polishing coating traces from being generated on the thermal spray coating surface D due to the traverse operation. It is possible to finish with higher accuracy than required.

  In the first polishing step, the traverse operation is executed as many times as the thermal spray coating surface D is finished to a predetermined surface roughness, and the process is terminated. The operation cycle of the vibration operation is appropriately set in the range of 150 to 1000 times / min, and the operation cycle of the traverse operation is also appropriately set in the range of 1 to 3 times / min.

[Second polishing step]
In the second polishing step, after the first polishing step is finished, as shown in FIG. 3, the vibration operation is stopped from being applied to the polishing tool T and the inner cylinder body 3a is not vibrated. The traverse operation is applied to the polishing tool T while being in contact with the thermal spray coating surface D.

  In addition, the operation cycle of the traverse operation in the second polishing step may be the same as or different from the first polishing step, and is appropriately set in the range of 1 to 3 times / min.

  A cross-hatch pattern resulting from the vibration operation is formed on the sprayed coating surface D after the first polishing step, but in the second polishing step, a polishing process in which only the traverse operation is applied to the polishing tool T is performed. The cross hatch pattern formed in the first polishing step can be eliminated while maintaining the highly accurate surface roughness obtained in the one polishing step.

  In the second polishing step, the traverse operation is executed as many times as the cross hatch pattern formed on the sprayed coating surface D disappears, and the process ends.

C. Summary As described above, in the surface treatment method according to the present embodiment, the polishing tool T has a combined operation in which the vibration operation and the traverse operation are combined with respect to the sprayed coating surface D of the inner cylinder main body 3a on which the sprayed coating is formed. Since the first polishing step of applying and polishing, and the second polishing step of applying only the traverse operation to the polishing tool T and performing the polishing are sequentially performed, the sprayed coating surface D of the inner cylinder main body 3 a The surface roughness can be finished with high accuracy and a polished surface having no cross hatch pattern.

  Therefore, even if the inner cylinder main body 3a processed by the surface treatment method according to the present embodiment is used as a part of the leg device 1, fluid leakage due to the cross hatch pattern, which has been a problem in the past, occurs. There is nothing.

  Needless to say, in the present embodiment, there is no problem even if rough polishing is performed prior to the first polishing step described above.

  Each inner cylinder main body 3a according to Examples 1 and 2 and Comparative Examples 1 and 2 was created, and the surface roughness and polishing traces were evaluated, and an operation test was performed to observe the leakage state of the internal fluid. . The results are shown in FIGS.

  In Examples 1 and 2 and Comparative Examples 1 and 2, a thermal spray coating of tungsten carbide having a coating thickness of about 0.1 mm was formed in the spray coating formation step. In addition, the operation test was performed by assembling the obtained inner cylinder body 3a as the leg device 1, enclosing the fluid at 900 psi (initial enclosure pressure), and adjusting the expansion / contraction stroke amount of the inner cylinder body 3a from the fully extended state. It was stretched about 100 to 7.5 inches and then held overnight in a fully stretched state, and the leakage state of the fluid was observed. The polishing conditions in Examples 1 and 2 and Comparative Examples 1 and 2 were as follows.

[Example 1]
The inner cylinder body 3a was rotated so that the peripheral speed of the outer peripheral surface of the inner cylinder body 3a was 18.3 m / min, and the first polishing process and the second polishing process were performed. In the first polishing step, a diamond grindstone of # 1000 (average abrasive grain size: 14 to 22 μm) was used, the stroke of the vibration operation was 2.5 mm, and the operation cycle was 600 times / min. Further, the operation cycle of the traverse operation was set to 2 times / min. In the second polishing step, a diamond grindstone with # 2000 (average abrasive grain size of 5 to 10 μm) was used, and the operation cycle of the traverse operation was set to 2 times / min.

[Example 2]
The inner cylinder body 3a was rotated so that the peripheral speed of the outer peripheral surface of the inner cylinder body 3a was 30.4 m / min, and the first polishing process and the second polishing process were performed. In the first polishing step, a diamond grindstone of # 1000 (average abrasive grain size: 14 to 22 μm) was used, the stroke of the vibration operation was 2.5 mm, and the operation cycle was 600 times / min. Further, the operation cycle of the traverse operation was set to 2 times / min. In the second polishing step, a diamond grindstone with # 2000 (average abrasive grain size of 5 to 10 μm) was used, and the operation cycle of the traverse operation was set to 2 times / min.

[Comparative Example 1]
Only the first polishing step was performed by rotating the inner cylinder main body 3a so that the peripheral speed of the outer peripheral surface of the inner cylinder main body 3a was 18.3 m / min. In the first polishing step, a diamond grindstone of # 1000 (average abrasive grain size: 14 to 22 μm) was used, the stroke of the vibration operation was 2.5 mm, and the operation cycle was 600 times / min. Further, the operation cycle of the traverse operation was set to 2 times / min.

[Comparative Example 2]
The inner cylinder body 3a was rotated so that the peripheral speed of the outer peripheral surface of the inner cylinder body 3a was 18.3 m / min, and the first polishing step was performed twice. In the first machining, a diamond grindstone of # 1000 (average abrasive grain size of 14 to 22 μm) is used, the stroke of the vibration operation is 2.5 mm, the operation cycle is 600 times / min, and the operation cycle of the traverse operation Was set to 2 times / min. In the second processing, a diamond grindstone of # 2000 (average abrasive grain size is 5 to 10 μm) is used, the stroke of the vibration operation is 2.5 mm, the operation cycle is 600 times / min, and the operation cycle of the traverse operation Was set to 2 times / min.

[Evaluation]
FIG. 4 is a table summarizing the measurement results of the surface roughness of the thermal spray coating surface D of the inner cylinder main body 3a according to Examples 1 and 2 and Comparative Examples 1 and 2, and Ra in the table is arithmetic average roughness, Rp represents the maximum peak height of the roughness curve, and Rz represents the maximum height roughness (all of Ra, Rp, and Rz conform to JIS B 0601). 5 to 8 are photographs showing the outer peripheral surface of the inner cylinder main body 3a after the operation test. FIG. 5 shows Example 1, FIG. 6 shows Example 2, FIG. 7 shows Comparative Example 1, and FIG. 8 is a photograph showing the outer peripheral surface of the inner cylinder main body 3a in Comparative Example 2.

  First, as shown in FIG. 4, in Comparative Example 1 in which the first polishing process was performed only once, Ra, Rp, and Comparative Example 2 were compared with Examples 1, 2 and 2 in which the polishing process was performed twice. It is worse for any value of Rz. From this, it can be understood that the surface roughness can be finished with higher accuracy if the polishing process is performed for a longer time.

  Further, when Example 1 and Example 2 are compared with Comparative Example 2, Comparative Example 2 in which the polishing process in which the vibration operation is applied to the grindstone is performed twice is any value of Ra, Rp, and Rz. From this fact, it can be seen that the surface roughness can be finished with high accuracy by performing polishing with a vibration operation applied to the grindstone. On the other hand, in Example 1, Example 2, and Comparative Example 2, compared with Comparative Example 1, there is no great difference in any of Ra, Rp, and Rz, and a polishing process in which a vibration operation is applied to the grindstone is performed. It can be seen that the surface roughness can be sufficiently finished with high precision also in Example 1 and Example 2 in which the first polishing process and the second polishing process are performed as compared with Comparative Example 2 performed twice.

  Further, when comparing the first embodiment with the second embodiment, the second embodiment has a smaller value for each of Ra, Rp, and Rz. From this, the rotational speed of the inner cylinder main body 3a is increased. It can be seen that the surface roughness can be finished with high accuracy.

  From the above results, it can be seen that the surface roughness can be sufficiently finished with high accuracy by performing the first polishing step and the second polishing step.

  When the thermal spray coating surface of the inner cylinder main body 3a according to Examples 1 and 2 and Comparative Examples 1 and 2 is observed, any one of the thermal spray coating surfaces in Example 1 shown in FIG. 5 and Example 2 shown in FIG. However, no cross hatch pattern is formed. On the other hand, in Comparative Example 1 shown in FIG. 7 and Comparative Example 2 shown in FIG. 8, a cross hatch pattern is formed on the surface of each thermal spray coating. Therefore, as described above, it can be seen that the cross hatch pattern formed by the first polishing process disappears by performing the second polishing process.

  As can be seen from FIGS. 7 and 8, in both cases of Comparative Examples 1 and 2, a large amount of shavings of the seal member 6a adheres in an island shape and is formed on the surface of the sprayed coating. It can be seen that the seal member 6a is greatly scraped off by the pattern. In this case, fluid leakage from the seal portion by the seal member 6a was confirmed in any case.

  On the other hand, as can be seen from FIGS. 5 and 6, in the first embodiment, the shavings of the seal member 6 a are attached in a small amount like islands, but in the second embodiment, the shavings of the sealing member 6 a are not attached at all. However, when the cross hatch pattern is not formed on the surface of the sprayed coating, it is understood that the seal member 6a is difficult to be scraped off. And about Example 1 and 2, the leakage from the said seal part of the fluid which filled was not confirmed.

  From the above results, the first polishing step of polishing the thermal spray coating surface D of the inner cylinder main body 3a on which the thermal spray coating is formed by applying a composite operation in which the vibration operation and the traverse operation are combined to the polishing tool T, and polishing, By sequentially performing the second polishing step in which only the traverse operation is applied to the polishing tool T for polishing, as described above, the thermal spray coating surface D of the inner cylinder main body 3a has a highly accurate surface roughness. A polished surface having no cross hatch pattern can be finished, and the inner cylinder body 3a subjected to the surface treatment in this manner may cause a fluid leakage which has been a problem in the past even if it is used as a component of the leg device 1. I understand that there is no.

DESCRIPTION OF SYMBOLS 1 Aircraft leg apparatus 2 Outer cylinder 3 Inner cylinder 3a Inner cylinder main body 3b Upper bearing 6a, 6b Seal member 7 Lower bearing 10 Polishing apparatus 11 Spindle 12 Chuck 13 Core support 14 Grinding wheel base T Polishing tool

Claims (4)

A cylindrical body having an internal space; a cylindrical or rod-shaped movable body that is movably inserted in the internal space of the cylindrical body; and an inner peripheral surface of the cylindrical body and an outer peripheral surface of the movable body The movement in a cylindrical hydraulic / pneumatic apparatus provided with a seal member disposed between and in sliding contact with the outer peripheral surface of the movable body to prevent leakage of a fluid filled in the internal space of the tubular body A method for surface treatment of the outer peripheral surface of a body,
A coating forming step of forming a thermal spray coating containing tungsten by a thermal spraying method on at least an outer peripheral surface of the movable body that is in sliding contact with the seal member;
In a state where the movable body is rotated about the axis, a polishing working surface of a polishing tool provided with at least one of diamond particles and cubic boron nitride particles as abrasive grains is brought into contact with the sprayed coating surface of the movable body. A combined operation of a vibration operation that reciprocates a predetermined distance along the central axis direction of the moving body and a traverse operation that reciprocates the entire area of the sprayed coating along the central axis direction of the moving body. A first polishing step for applying to the polishing tool and polishing the sprayed coating surface;
The polishing surface of the polishing tool is brought into contact with the sprayed coating surface of the moving body while the moving body is rotated about the axis, and only the traverse operation is applied to the polishing tool, and the first polishing step And a second polishing step of polishing the sprayed coating surface on which the thermal spraying is completed.   2. The surface treatment method for a moving body according to claim 1, wherein, in the second polishing step, the moving body is rotated so that a peripheral speed of an outer peripheral surface thereof is 11 m / min or more. A cylinder having an internal space;
A cylindrical or rod-like moving body that is inserted into the inner space of the cylindrical body so as to be movable in the axial direction of the cylindrical body,
It is disposed between the inner peripheral surface of the cylindrical body and the outer peripheral surface of the movable body and is in sliding contact with the outer peripheral surface of the movable body to prevent leakage of the fluid filled in the internal space of the cylindrical body. A sealing member,
The moving body is
A film forming step of forming a sprayed coating containing tungsten by a thermal spraying method on at least an outer peripheral surface that is in sliding contact with the seal member;
In a state where the movable body is rotated about the axis, a polishing working surface of a polishing tool provided with at least one of diamond particles and cubic boron nitride particles as abrasive grains is brought into contact with the sprayed coating surface of the movable body. A combined operation of a vibration operation that reciprocates a predetermined distance along the central axis direction of the moving body and a traverse operation that reciprocates the entire area of the sprayed coating along the central axis direction of the moving body. A first polishing step for applying to the polishing tool and polishing the sprayed coating surface;
The polishing surface of the polishing tool is brought into contact with the sprayed coating surface of the moving body while the moving body is rotated about the axis, and only the traverse operation is applied to the polishing tool, and the first polishing step A cylindrical hydraulic / pneumatic apparatus characterized in that the outer peripheral surface is surface-treated by sequentially performing a second polishing step of polishing the sprayed coating surface after completion of the step.   The said mobile body is rotated so that the peripheral speed of the said mobile body outer peripheral surface in the said 2nd grinding | polishing process may be 11 m / min or more, The outer peripheral surface is surface-treated. Cylindrical hydraulic / pneumatic equipment.