JP5726673B2 - Sliding surface structure - Google Patents

Description

  The present invention relates to a sliding surface structure.

  Surface texturing is one of the methods for improving sliding characteristics, such as expanding the fluid lubrication area and reducing friction. Grating-like periodic structure with submicron periodic pitch and groove depth is known to have extremely high load capacity and rigidity at submicron oil film thickness, and is used for reciprocating sliding and rotational sliding. Has been.

  However, in situations where sufficient dynamic pressure cannot be obtained, such as immediately after starting or immediately before stopping, aggression by the periodic structure part becomes a problem. Here, the aggression property by the periodic structure portion is wear increase property or damage property to the counterpart member. In order to reduce the aggressiveness of the periodic structure portion, it is effective to make the height of the convex portion of the periodic structure portion lower than the height flush with the portion where the periodic structure is not formed.

  Therefore, conventionally, there is a thrust bearing in which a convex portion whose height is higher than the convex portion of the periodic structure portion is provided on the rotation center portion on the sliding surface (Patent Document 1). In this thrust bearing, when the rotation is stopped, the entire sliding surface (the surface facing the mating sliding surface) is in contact with the apex of the convex portion without contacting the mating sliding surface. For this reason, at the time of start-up, the contact between the apex of the convex portion and the other-side sliding surface is limited to the vicinity of the rotation center, and the influence on the start-up torque due to friction is made small.

JP 2001-12456 A

  In the thing of patent document 1, it is necessary to form a convex part on a sliding surface. As a forming method in this case, there is a method of forming the convex portion as a separate member and then joining the sliding surface, or a method of cutting or grinding so as to leave the convex portion. For this reason, any of the forming methods has many processing steps and is inferior in productivity.

  Moreover, the oil film formed in a periodic structure part tends to become thick by forming a convex part. Thus, when the oil film becomes thick, low load capacity and low rigidity are caused.

  If the height of the convex portion of the periodic structure portion is made lower than the height flush with the portion where the periodic structure is not formed, the load capacity is adversely affected. Therefore, it is desired to develop a patterning that does not affect the load capacity and to set an appropriate height.

  In view of the above problems, the present invention provides a sliding surface structure that can reduce the aggressiveness of a periodic structure part while suppressing a reduction in load capacity.

The sliding surface structure of the present invention is a sliding surface structure in which the sliding surface of the first member and the sliding surface of the second member slide relative to each other under a lubricant. On the sliding surface of at least one of the members, the periodic structure portions of the grating-like unevenness and the non-periodic structure forming portions are alternately formed along the sliding direction, and the convex portion height position of the periodic structure portion the set lower than the height position of the unformed portions, Rutotomoni to generate pressure at the interface between the periodic structure portion and the periodic structure unformed portion, the periodic structure portion is communicated with the sliding surface periphery, the fluid Introduced inside the sliding surface .

  According to the sliding surface structure of the present invention, by setting the convex portion height position of the periodic structure portion to be lower than the height position of the non-formed portion, the periodic structure portion is activated at the time of sliding start and at the time of sliding stop. Aggression is reduced. Here, the aggression property by the periodic structure portion is wear increase property or damage property to the counterpart member. In addition, since the periodic structure portion communicates with the periphery of the sliding surface, the lubricant can be introduced into the sliding surface from the periphery of the sliding surface by the sliding operation of the first member and the second member ( This action is called a fluid introduction effect). The periodic structure portion and the periodic structure non-formed portion are alternately formed along the sliding direction, and the period height is set by setting the convex portion height position of the periodic structure portion lower than the height position of the non-formed portion. Pressure is generated at the boundary between the structure portion and the unformed portion, and a pressure gradient is generated in the sliding direction (this action is called a step effect). Thus, by providing the periodic structure portion and the non-formed portion, the reduction in load capacity can be reduced even if the height difference between the height position of the convex portion of the periodic structure portion and the height position of the non-formed portion is increased. .

  Therefore, the sliding surface structure of the present invention has both the fluid introduction effect and the step effect. The load capacity due to the step effect is less affected by the height position of the convex portion of the periodic structure portion being lower than the height position of the portion where the periodic structure is not formed, compared with the load capacity due to the fluid introduction effect.

  It is preferable that the height difference between the height position of the convex portion of the periodic structure portion and the height position of the non-formed portion is equal to or greater than the arithmetic average roughness of the sliding surface. Moreover, it is preferable that the height difference between the height position of the convex portion of the periodic structure portion and the height position of the non-formed portion is equal to or less than the maximum height roughness of the sliding surface.

  The periodic pitch of the periodic structure portion is preferably 10 μm or less, and the depth of the concave portion of the periodic structure portion is preferably 1 μm or less.

  The periodic structure portion is preferably formed in a self-organized manner by irradiating a linearly polarized laser beam with an irradiation intensity in the vicinity of the processing threshold and scanning the overlapped portion in an overlapping manner. Moreover, it is preferable that the periodic structure portion and the height difference are formed by simultaneous processing.

  In the sliding surface structure of the present invention, the aggression by the periodic structure portion at the time of sliding start and stop is mitigated, the increase in wear of the mating member can be prevented, and the sliding surface structure has a stable function over a long period of time. It can be demonstrated. In addition, since the fluid introduction effect and the step effect are combined, the aggressiveness of the periodic structure portion can be effectively mitigated while keeping the load capacity from being reduced, and a high quality sliding surface structure can be provided.

  If the height difference between the convex part height position of the periodic structure part and the height position of the non-formed part is equal to or greater than the arithmetic average roughness of the sliding surface, sufficient dynamic pressure cannot be obtained immediately after starting or immediately before stopping. Even in a scene, the periodic structure part slides with almost no load support. For this reason, the aggressiveness of a periodic structure part can be reduced significantly.

  If the height difference between the height position of the convex portion of the periodic structure portion and the height position of the non-formed portion is set to be equal to or less than the maximum height roughness of the sliding surface, a significant reduction in load capacity can be prevented. .

  When the concavo-convex pitch of the periodic structure portion is 10 μm or less, the leakage of the lubricant (side leakage) can be suppressed redundantly, and the dynamic pressure can be obtained efficiently. When the depth of the concave portion of the periodic structure portion is 1 μm or less, variation in the flying height when dynamic pressure is generated can be reduced, which contributes to improvement in rigidity.

  The periodic structure is irradiated with a linearly polarized laser beam with an irradiation intensity in the vicinity of the processing threshold, scanned while overlapping the irradiated part, and formed by self-organization. Those having a pitch and a depth of unevenness can be easily formed.

  In the case where the periodic structure portion and the height difference are formed by simultaneous processing, the processing time can be shortened, and the productivity can be improved and the cost can be reduced. Simultaneous processing is possible by adjusting the output of the laser, and the height difference can be formed with the periodic structure portion with high accuracy and stability.

It is a principal part expanded sectional view of the sliding surface structure which shows embodiment of this invention. FIG. 2 is a simplified diagram of a sliding surface having a periodic structure portion of the sliding surface structure shown in FIG. 1. It is an enlarged view of the periodic structure part formed in the said sliding surface. It is a simplification figure of the laser surface processing apparatus for forming the said periodic structure part. FIG. 6 is a simplified view of a sliding surface in which the groove direction of the periodic structure portion is a direction that is alternately opposed along the sliding direction. It is a simplified view of a sliding surface on which a periodic structure portion of a reciprocating sliding pattern is formed. It is a simplified diagram of a sliding surface on which a periodic structure part of a spiral pattern is formed. It is a simplified diagram of a sliding surface on which a periodic structure portion of a step pattern is formed. It is a graph which shows the relationship between digging depth and load capacity. It is a graph which shows the relationship between digging depth and load capacity. It is a graph which shows the relationship between a sliding speed and a friction coefficient. It is a graph for demonstrating the definition of arithmetic mean roughness. It is a graph for demonstrating the definition of maximum height roughness.

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

  As shown in FIG. 1, the sliding surface structure according to the present invention is such that the sliding surface 1a of the first member 1 and the sliding surface 2a of the second member 2 slide relative to each other under the lubricant L. It is. In this case, the first member 1 and the second member 2 may be carbon steel, copper, aluminum, platinum, cemented carbide, silicon ceramics such as silicon carbide or silicon nitride, engineer plastic, etc. It may be. Further, the lubricant L may be water or alcohol, or may be a lubricating oil such as engine oil. That is, various lubricants can be used depending on the material of the first and second members 1 and 2 and the environment in which they are used. Moreover, the 1st member 1 was made into the ring body as shown, for example in FIG. 2, and the 2nd member 2 was comprised by the disk shaped body, for example.

  The upper surface of the first member 1 becomes the sliding surface 1a, and the lower surface of the second member 2 becomes the sliding surface 2a. A plurality of grating-like irregular periodic structures 3 are formed on the sliding surface 1a of the first member 1 at a predetermined pitch in the circumferential direction. That is, the periodic structure portions 3 and the non-periodic structure portion 4 having grating-like irregularities are alternately formed along the sliding direction.

  As shown in FIG. 3, the periodic structure portion 3 is formed by alternately arranging minute concave portions 5 and minute convex portions 6 at a predetermined pitch. It is preferable that the irregular pitch of the periodic structure portion 3 is 10 μm or less and the depth of the concave portion 5 is 1 μm or less. In this case, the concave portion 5 of the periodic structure portion 3 communicates (opens) with the outer peripheral edge (sliding surface peripheral edge) 1 b of the first member 1. There is no opening in the inner peripheral edge 1 c of the first member 1.

  The periodic structure portion 3 is curved in a spiral shape, the bending direction of each periodic structure portion 3 is set to be the same, and at least one of the first member 1 and the second member 2 rotates about its axis. Thus, the periodic structure portion 3 of the first member 1 is set such that the lubricant is introduced into the first member 1 from the outer peripheral side of the sliding surface 1a.

  The periodic structure portion 3 is formed in a self-organized manner by irradiating a linearly polarized laser beam with an irradiation intensity in the vicinity of the processing threshold and scanning the overlapping portions in an overlapping manner. Specifically, the femtosecond laser surface processing apparatus shown in FIG. 4 is used. A laser (eg, pulse width: 120 fs, center wavelength: 800 nm, repetition frequency: 1 kHz, pulse energy: 0.25 to 400 μJ / pulse) generated by a laser generator 11 (titanium sapphire femtosecond laser generator) is reflected by a mirror 12. It is folded back toward the work material W and guided to the mechanical shutter 13. At the time of laser irradiation, the mechanical shutter 13 is opened, the laser irradiation intensity can be adjusted by the half-wave plate 14 and the polarization beam splitter 16, the polarization direction is adjusted by the half-wave plate 15, and the condenser lens (focal length) : 150 mm) 17, the surface of the work material W on the XYθ stage 19 is condensed and irradiated. A femtosecond laser is a light source that compresses energy in an extremely short time unit of the order of femtoseconds (one thousandth of a second).

  That is, when a workpiece (working material) W is irradiated with a linearly polarized laser beam at a fluence near the ablation threshold, the pitch and grooves on the order of wavelengths are caused by interference between incident light and scattered light or plasma waves along the surface of the processing material W. A grating-like periodic structure having a depth is formed in a self-organizing manner perpendicular to the polarization direction. At this time, the periodic structure part can be expanded over a wide range by scanning the femtosecond lasers while overlapping them.

  Laser scanning may be performed by moving the XYθ stage 19 that supports the processing material W while fixing the laser, or may move the laser while fixing the XYθ stage 19. Alternatively, the laser and the XYθ stage 19 may be moved simultaneously. In addition, the said FIG. 3 is the figure which imaged the periodic structure part 3 formed with the said femtosecond laser surface processing apparatus with the electron microscope.

  And in the sliding surface structure of this invention, as shown in FIG. 1, the convex part height position of the periodic structure part 3 is set lower than the height position of the non-formation part 4. As shown in FIG. The height difference between the convex portion height position 10 of the periodic structure portion 3 and the height position 11 of the non-formed portion 4 is defined as the sliding surface 1a (the inner diameter side of the non-formed portion 4 and the periodic structure portion 3 on the upper surface of the first member 1). Of the average surface roughness Ra). Further, this height difference is set to be equal to or less than the maximum height roughness Rz of the sliding surface 1a.

As shown in FIG. 12, the arithmetic average roughness Ra is obtained by extracting only the reference length from the roughness curve in the direction of the average line, the X axis in the direction of the average line m of the extracted portion, and the direction of the vertical magnification. When the Y-axis is taken and the roughness curve is represented by y = f (x), the value obtained by the following equation 1 is represented by micrometers (μm).

  Further, as shown in FIG. 13, the maximum height roughness Rz is obtained by extracting only the reference length from the roughness curve in the direction of the average line m, and roughening the interval between the peak line and the valley line of the extracted part. It is measured in the direction of the vertical magnification of the curve, and this value is expressed in micrometers (μm). That is, (Rz = Rp + Rv).

  In the present invention, as shown in FIG. 1, the digging depth (height difference) T from the sliding surface 1 a to the convex portion height position 10 of the periodic structure portion 3 is referred to as the height of the convex portion 6 of the periodic structure portion 3. The depth (depth of the concave portion 5 of the periodic structure portion 3) is called a periodic structure portion depth T1, and the gap between the sliding surfaces during the sliding motion is called a smooth portion clearance S.

  The periodic structure portion 3 and the height difference (digging depth) T can be formed by simultaneous processing. That is, in the femtosecond laser surface processing apparatus, when the periodic structure portion 3 is formed, the simultaneous processing can be performed by adjusting the output of the laser.

  In the sliding surface structure of the present invention, the convex structure height position 10 of the periodic structure portion 3 is set lower than the height position 11 of the non-formed portion 4, so that the periodic structure at the time of sliding start and at the time of sliding stop is set. The aggression by the part is reduced. Here, the aggression property by the periodic structure part 3 is wear increase property or damage property to the counterpart member. Further, since the periodic structure portion 3 communicates with the sliding surface peripheral edge 1b, the lubricant L is introduced from the sliding surface peripheral edge 1b into the sliding surface inward by the sliding operation of the first member and the second member. (This action is called the fluid introduction effect). The periodic structure portions 3 and the non-formed portions 4 are alternately formed along the sliding direction, and the convex portion height position 10 of the periodic structure portion 3 is set lower than the height position 11 of the non-formed portion 4. Thus, pressure is generated at the boundary between the periodic structure portion 3 and the non-formed portion 4, and a pressure gradient is generated in the sliding direction (this action is called a step effect). As described above, by providing the periodic structure portion 3 and the non-formed portion 4, even if the height difference between the convex portion height position 10 of the periodic structure portion 3 and the height position 11 of the non-formed portion 4 is increased, the load is increased. The decrease in capacity can be reduced.

  Therefore, the sliding surface structure of the present invention has both the fluid introduction effect and the step effect. The load capacity due to the step effect is less affected by the fact that the convex height position 10 of the periodic structure portion 3 is lower than the height position 11 of the periodic structure-unformed portion 4 compared to the load capacity due to the fluid introduction effect.

  That is, in the sliding surface structure of the present invention, the aggression by the periodic structure portion 3 at the time of starting and stopping the sliding is mitigated, and increase in wear of the counterpart member (in this case, the second member 2) can be prevented. As a sliding surface structure, a stable function can be exhibited over a long period of time. In addition, since the fluid introduction effect and the step effect are combined, the aggressiveness of the periodic structure portion 3 can be effectively mitigated while suppressing the reduction of the load capacity, and a high quality sliding surface structure can be provided.

  If the height difference between the height position 10 of the convex portion 3 of the periodic structure portion 3 and the height position 11 of the non-formed portion 4 is equal to or greater than the arithmetic average roughness of the sliding surface, sufficient dynamic pressure such as immediately after starting or immediately before stopping. Since the periodic structure portion 3 slides with almost no load support even in a situation where the above cannot be obtained, the aggressiveness of the periodic structure portion 3 can be greatly reduced.

  If the height difference between the convex part height position 10 of the periodic structure part 3 and the height position 11 of the non-formed part 4 is less than or equal to the maximum height roughness of the sliding surface 1a, a significant reduction in load capacity is prevented. can do.

  When the concavo-convex pitch of the periodic structure portion 3 is 10 μm or less, leakage of the lubricant L (side leakage) can be suppressed redundantly, and dynamic pressure can be obtained efficiently. When the depth of the concave portion 5 of the periodic structure portion 3 is 1 μm or less, variation in the flying height when dynamic pressure is generated can be reduced, which contributes to improvement in rigidity.

  The periodic structure is irradiated with a linearly polarized laser beam with an irradiation intensity in the vicinity of the processing threshold, scanned while overlapping the irradiated part, and formed by self-organization. Those having a pitch and a depth of unevenness can be easily formed.

  If the periodic structure portion 3 and the height difference are formed by simultaneous machining, the machining time can be shortened, and the productivity can be improved and the cost can be reduced. Simultaneous machining is possible by adjusting the output of the laser, and the height difference can be formed with the periodic structure portion 3 stably and with high accuracy.

  Next, FIG. 5 shows a symmetrical shape in the periodic structure portion 3 adjacent in the circumferential direction. That is, for example, if the rotation direction of the second member 2 is the clockwise direction (arrow A direction), the lubricant introduction effect of introducing the lubricant L into the inside of the periodic structure portion 3a is exhibited. For this reason, even in this case, the fluid introduction effect and the step effect are combined. In addition, in the periodic structure part 3b between 3a and 3a, the lubricant L is discharged from the inside to the peripheral edge 1b.

  In the sliding surface structure shown in FIG. 5, if the rotation direction of the second member 2 is the counterclockwise direction (arrow B direction), the lubricant introduction into which the lubricant L is introduced into the periodic structure portion 3b is provided. The effect is demonstrated. For this reason, even in this case, the fluid introduction effect and the step effect are combined. In addition, in the periodic structure part 3a between 3b and 3b, the lubricant L is discharged from the inside to the peripheral edge 1b.

  In each of the embodiments described above, the sliding direction is the rotational direction, but FIG. 6 shows a sliding surface 1a having a sliding surface structure in which the sliding direction is a linear direction. In this case, the periodic structure portions 3 and the periodic structure non-formed portions 4 are alternately formed along the sliding direction.

  Moreover, it forms so that the direction of the periodic structure part 3 adjacent along a sliding direction may become symmetrical. That is, when the sliding direction of the second member 2 is the arrow C direction, the periodic structure portion 3c exhibits the lubricant introduction effect of introducing the lubricant L into the interior as indicated by the arrow E, and the periodic structure portion 3d. Exhibits the lubricant discharging effect of discharging the lubricant L to the outside as indicated by the arrow F. Further, when the sliding direction of the second member 2 is the direction of the arrow D, the 3d periodic structure portion exhibits a lubricant introduction effect of introducing the lubricant L therein, and the 3c periodic structure portion applies the lubricant L. Demonstrates the effect of discharging the lubricant discharged to the outside. Therefore, even in this case, both the fluid introduction effect and the step effect are provided.

  As mentioned above, although it demonstrated per embodiment of this invention, this invention is not limited to the said embodiment, A various deformation | transformation is possible, for example, in the said embodiment, the periodic structure part 3 is set to the 2nd member 2 side. It may be formed on both sides of the first member 1 and the second member 2. Further, the shapes of the first member 1 and the second member 2 are not limited to those in the illustrated example, and can be configured in other various shapes. The size, arrangement pitch, and the like of the periodic structure portion 3 can be variously changed according to the size, material, lubricant type, sliding speed, and the like of the first and second members to be used.

  Even if the relative sliding movement between the first member 1 and the second member 2 fixes the first member 1 and reciprocates the second member 2, the second member 2 side is fixed on the contrary. The first member side may be slid. That is, the direction where the periodic structure part 3 is formed may be slid, or the direction where the periodic structure part 3 is not formed may be slid. Further, both the first member 1 and the second member 2 may be slid.

  In the embodiment shown in FIGS. 2 and 5, the number of the periodic structure portions 3 is six and the number of the unformed portions 4 is six. Also in the embodiment shown in FIG. 6, the periodic structure portions are arranged along the sliding direction. However, the present invention is not limited to these, and the periodic structure portion 3 can be arbitrarily increased or decreased. Moreover, the circumferential direction length, radial direction length, etc. of the one periodic structure part 3 and the non-formation part 4 can also be set arbitrarily. However, since the step effect is affected by the circumferential length and radial length of the periodic structure portion 3 and the non-formed portion 4, the circumferential length of the periodic structure portion 3 is about 1 to 5 times the radial length. It is preferable to do. The circumferential length of the non-formed portion 4 is preferably about 0.2 to 2.0 times the circumferential length of the periodic structure portion 3.

  By the way, in the said embodiment, when forming the periodic structure part 3, the femtosecond laser which is a pulse laser was used, However, Pulse lasers, such as picosecond lasers and nanosecond lasers other than a femtosecond laser, can also be used. .

  According to the sliding surface structure of the present invention, the fluid introduction effect and the step effect can be exhibited and low friction can be obtained. For this reason, the sliding surface structure of the present invention can be used for various devices such as various automobile parts, machine parts, and pumps.

  The influence of the drilling depth T on the load capacity was investigated. First, a spiral pattern (FIG. 7) in which a periodic structure (pitch 0.7 μm, depth 0.2 μm) is formed in a spatial shape and a step pattern (FIG. 8) in which a concentric periodic structure 3 is intermittently formed. The load capacity was calculated using infinite groove number theory. That is, in FIG. 8, the periodic structure portions 3 (3e) formed along the circumferential direction and the non-formed portions 4 where the periodic structure portions 3 are not formed are alternately arranged in the circumferential direction between the periodic structure portions 3e. It was established. In this case, the periodic structure portion 3 is not communicated with the sliding surface peripheral edge 1b.

  In the sliding surface structure in which the spiral pattern shown in FIG. 7 is formed, a load capacity is generated mainly by the pumping action by the fluid introduction effect of the periodic structure portion 3. At this time, a large pressure gradient is generated in the radial direction, but almost no pressure gradient is generated in the circumferential direction (sliding direction) because the interval between the periodic structures is fine. On the other hand, in the sliding surface structure in which the step pattern shown in FIG. 8 is formed, pressure is generated at the boundary between the periodic structure portion arranged in the circumferential direction and the non-formed portion, so that a large pressure in the circumferential direction (sliding direction). A gradient occurs. However, since the periodic structure portion 3 is not communicated with the sliding surface peripheral edge 1b, it does not have a fluid introduction effect.

  FIG. 9 shows the relationship between the digging depth T and the load capacity when the smooth portion clearance S is 0.2 μm and the periodic structure portion forming regions of both patterns are optimized. In the sliding surface structure in which the spiral pattern shown in FIG. 7 is formed, a large load capacity is obtained when the digging depth T is 0, but the load capacity decreases exponentially as the digging depth T increases. Further, in the sliding surface structure in which the step pattern shown in FIG. 8 is formed, the load capacity once increases due to the increase in the digging depth and then gradually decreases. That is, the load capacity of the step pattern is less affected by the digging depth T compared to the spiral pattern, and when the digging depth T is 0.1 μm, the load capacity of the step pattern is slightly larger than the spiral pattern.

  On the other hand, as in the intermittent spiral pattern (pattern of the present invention) shown in FIG. 2, the periodic structure portions 3 and the unformed portions 4 communicating with the sliding surface peripheral edge 1b are alternately arranged along the sliding direction. However, by combining the fluid introduction effect and the step effect, it is possible to provide a sliding surface structure that can reduce the aggression of the periodic structure portion 3 while keeping the load capacity from being reduced.

  FIG. 10 is obtained by adding the calculation result of the load capacity of the intermittent spiral pattern to FIG. The intermittent spiral pattern has characteristics of a spiral pattern and a step pattern, and a load capacity exceeding the step pattern is obtained in all regions. 9 and 10 is an arbitrary unit (au).

  Next, an experiment using a ring-on-disk test apparatus was performed. The disk test piece constituting the second member 2 was used as a stationary test piece, and the ring test piece constituting the first member 1 was used as a rotation side test piece. Each test piece was finished to have a surface roughness Ra of 0.02 μm and Rz of 0.15 μm. The disk test pieces were all mirror surfaces, and the ring test pieces (outer diameter 16 mm, inner diameter 10 mm) were of two types: spiral pattern (FIG. 7) and intermittent spiral pattern (FIG. 2) (product of the present invention). The pitch of each periodic structure portion 3 was about 0.7 μm and the depth was about 0.2 μm. Further, the digging depth T in the present invention product was about 0.1 μm. Pure water was used as the lubricant. After fixing the load at 10N and starting from a static state at a sliding speed of 1.2m / s, measure the friction coefficient while gradually reducing the sliding speed to 0.15m / s every 5 minutes. The average coefficient of friction at speed was calculated.

  The experimental results of the friction coefficient at each sliding speed are shown in FIG. In the high slip rate region, both the spiral pattern and the intermittent spiral pattern were in a fluid lubrication state in which the friction coefficient decreased as the slip rate decreased. When the sliding speed of the spiral pattern was 0.35 m / s or less, the friction coefficient increased, and mixed lubrication was started. On the other hand, the intermittent spiral pattern (product of the present invention) having both the fluid introduction effect and the step effect maintains fluid lubrication up to 0.24 m / s, and it has been confirmed that a higher load capacity than the spiral pattern can be obtained.

DESCRIPTION OF SYMBOLS 1 1st member 1b Perimeter 1a, 2a Sliding surface 2 2nd member 3a, 3b, 3c, 3d, 3e Periodic structure part 4 Periodic structure non-formation part 5 Concave part 6 Protrusion part 10, 11 Height position

Claims (7)

A sliding surface structure in which the sliding surface of the first member and the sliding surface of the second member slide relative to each other under a lubricant, the sliding surface of at least one of the first member and the second member. On the moving surface, periodic structure parts of grating-like irregularities and non-periodic structure forming parts are alternately formed along the sliding direction, and the convex part height position of the periodic structure part is higher than the height position of the non-forming part. set is low, Rutotomoni to generate pressure at the interface between the periodic structure portion and the periodic structure unformed portion, the periodic structure portion is communicated with the sliding surface peripheral edge, introducing a fluid into the sliding face inwardly Sliding surface structure characterized by   2. The sliding surface structure according to claim 1, wherein a height difference between a height position of the convex portion of the periodic structure portion and a height position of the non-formed portion is equal to or greater than an arithmetic average roughness of the sliding surface. .   3. The height difference between the height position of the convex portion of the periodic structure portion and the height position of the non-formed portion is equal to or less than the maximum height roughness of the sliding surface. Sliding surface structure.   The sliding surface structure according to any one of claims 1 to 3, wherein a periodic pitch of the periodic structure portion is 10 µm or less.   The sliding surface structure according to any one of claims 1 to 4, wherein a depth of the concave portion of the periodic structure portion is 1 µm or less.   The periodic structure part is formed in a self-organized manner by irradiating a linearly polarized laser beam with an irradiation intensity in the vicinity of a processing threshold and scanning the overlapping part in an overlapping manner. The sliding surface structure according to claim 5.   The sliding surface structure according to claim 6, wherein the periodic structure portion and the height difference are formed by simultaneous processing.