Sliding member

Abstract

In a sliding member in which a low-hardness first member and a high-hardness second member slide via a lubricant, the shape relationship between a large undulation and a small roughness imparted to the first member is optimized, both the retention and wettability of the lubricant are improved, and the sintering resistance is further improved. In a sliding member in which a first member and a second member having a higher hardness than the first member slide with a lubricant interposed therebetween, an isotropic texture having a valley area of 1000-20000 [mu] m < 2 > / mm and an RLO ([lambda] c 0.08 mm) of 1-12% is imparted to a portion of the first member in contact with the second member.

Description

Technical Field

[0001] The present invention relates to a sliding component in which a low-hardness component and a high-hardness component slide via a lubricant. Background Art

[0002] Various proposals have been made to improve the durability of sliding parts in which two parts slide via a lubricant. For example, in order to improve the durability by improving the seizure resistance of rolling bearings, the surface of the retainer is roughened to increase the retention force of the lubricant.

[0003] For example, Patent Document 1 describes a rolling bearing in which a rough surface having tiny micro-recesses and a plurality of large recesses larger than the micro-recesses is provided on the inner circumferential surface of a retainer, and the large recesses are provided as grooves having a width of more than 0 μm and less than 5000 μm, the grooves are arranged in parallel with intervals, and the ratio of the width to the interval is more than 0% and less than 71.4%. In addition, it is described that the above-mentioned specific surface roughness is provided to a retainer or a sealing lip made of a resin such as polyphenylene sulfide as a retainer.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 6485014 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, there is no specific mention of micro-recesses in Patent Document 1. Although it is described that the micro-recesses allow the lubricant to move by capillary action, there are certain conditions for the roughness at which the lubricant wets and spreads, and therefore a sufficient effect cannot be expected.

[0009] Therefore, the object of the present invention is to optimize the shape relationship between large undulations and minute roughness imparted to the first component in a sliding component in which a first component with low hardness and a second component with high hardness slide via a lubricant, thereby improving both the retention and wettability of the lubricant and further improving the seizure resistance.

[0010] Means for solving problems

[0011] The mechanism of improved seizure resistance is considered to be that the large undulations act as oil storage, and the micro-concave-convex plays the role of supplying the base oil of the grease and the lubricating oil to the contact surface with the counterpart material, thereby maintaining the lubrication state of the sliding surface for a long time. Therefore, it is necessary to define the shapes of both the large undulations and the micro-concave-convex, and to balance the oil storage and the supply of the lubricant. By applying this technology to the surface of the first component with low hardness that contacts the second component with high hardness, it is possible to improve lubricity and reduce friction and wear, thereby improving the seizure resistance of the sliding component as a whole and achieving a longer life.

[0012] The present invention has been accomplished based on such findings, and the above-mentioned object of the present invention is achieved by the following [1] structure of a sliding component.

[0013] [1] A sliding component, characterized in that:

[0014] In the sliding member, a first member and a second member having a higher hardness than the first member slide with each other via a lubricant.

[0015] The contact portion of the first member that contacts the second member is provided with an isotropic texture, wherein the valley area of ​​the texture is 1000 μm 2 / mm or more and 20000μm 2 / mm or less, and RLo (λc=0.08mm) is 1% or more and 12% or less.

[0016] In addition, preferred embodiments of the sliding component of the present invention relate to the following [2] to [8].

[0017] [2] The sliding component according to [1], characterized in that

[0018] The valley area is 4000 μm 2 / mm or more and 12000μm 2 / mm or less.

[0019] [3] The sliding component according to [2], characterized in that:

[0020] The valley area is 6000 μm 2 / mm or more and 12000μm 2 / mm or less.

[0021] [4] The sliding component according to [3], characterized in that:

[0022] The valley area is 8000 μm 2 / mm or more and 10000μm 2 / mm or less.

[0023] [5] The sliding component according to any one of [1] to [4], characterized in that:

[0024] The first component is a resin component, and the second component is a metal component or a ceramic component.

[0025] [6] The sliding component according to [5], characterized in that:

[0026] The first member is a resin cage of a rolling bearing, and the second member is a metal rolling element or a ceramic rolling element.

[0027] [7] The sliding component according to [5], characterized in that

[0028] The second member is a metal rolling element or a ceramic rolling element of the linear motion device, and the first member is a spacer existing between the metal rolling elements or between the ceramic rolling elements.

[0029] [8] The sliding component according to [5], characterized in that

[0030] The first member is a gear made of resin, and the second member is a gear made of metal or ceramic.

[0031] Effects of the Invention

[0032] According to the sliding component of the present invention, by optimizing the shape relationship between the large undulations and the minute roughness formed on the sliding contact surface of the first component with low hardness that slides in contact with the second component with high hardness, the lubricity between the two components can be improved, and the friction and wear can be reduced, thereby improving the sintering resistance and achieving a further extended life of the sliding component. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a cross-sectional view showing an angular contact ball bearing as an example of the sliding component of the present invention.

[0034] Figure 2 This is a diagram showing the results of measuring the surface irregularities of the resin sample used in Experiment 1.

[0035] Figure 3A It is a diagram showing an example of calculation of the valley area.

[0036] Figure 3B is a flowchart showing a method for calculating the valley area.

[0037] Figure 4 is a graph showing the results of Experiment 1.

[0038] Figure 5 This is a graph collectively showing the valley areas and micro-roughness of the resin samples used in Experiment 2.

[0039] Figure 6 This is a graph collectively showing the valley areas and micro-roughness of the resin samples used in Experiment 2.

[0040] Figure 7 is a graph showing the results of Experiment 2.

[0041] Figure 8 This is a graph showing the relationship between RLo (λc=0.08 mm) and sintering life of a resin sample having a large oil storage capacity.

[0042] Fig. 9 This is a schematic diagram for explaining sampling in Experiment 3.

[0043] Fig.10 It is a graph which shows the result of Experiment 3 (RLo (λc=0.08 mm)).

[0044] Fig.11 This is a graph showing the results of Experiment 3 (valley area). DETAILED DESCRIPTION

[0045] As an embodiment of the sliding part of the present invention, a rolling bearing is used as an example to explain it below. In addition, this embodiment represents an example of the present invention, and the present invention is not limited to this embodiment. In addition, various changes or improvements can be applied to this embodiment, and the method of applying such changes or improvements is also included in the present invention.

[0046] In this embodiment, there is no limitation on the type of rolling bearing. Figure 1 The shown angular contact ball bearing is guided on the outer ring.

[0047] Figure 1 The angular contact ball bearing shown in the figure comprises: an inner ring 1 having a raceway surface 1a on the outer circumference; an outer ring 2 having a raceway surface 2a on the inner circumference opposite to the raceway surface 1a of the inner ring 1; a plurality of rolling elements (balls) 3 arranged to roll freely between the raceway surface 1a of the inner ring 1 and the raceway surface 2a of the outer ring 2; a retainer 4 that retains the plurality of rolling elements 3 between the inner ring 1 and the outer ring 2; and a contact type seal 5 that covers the opening of the gap between the inner ring 1 and the outer ring 2. In addition, the rolling element 3 is made of metal or ceramic, and corresponds to a "second member" with high hardness. In addition, the gap between the inner ring 1 and the outer ring 2 is filled with a lubricant such as grease or lubricating oil (not shown), and is sealed by the seal 5.

[0048] The retainer 4 is made of resin, for example, PPS (polyphenylene sulfide), polyamide, polyacetal, PEEK (polyetheretherketone resin), fluororesin can be used. In addition, the resin retainer 4 is equivalent to the "first component" with low hardness. In addition, it can also contain reinforcing materials such as glass fiber and carbon fiber. In addition, the shape of the retainer 4 is not limited, and it can be applied to all bearing retainers such as crown-shaped, corrugated, cage-shaped, and angular.

[0049] In the present embodiment, at least the contact surface of the cage 4 that contacts other members, namely, the inner surface of the pocket and the outer ring guide surface of the cage 4, is provided with a specific texture as described below, that is, a predetermined large undulation and a predetermined fine roughness.

[0050] The large undulations can be expected to retain the lubricant in the valley portion of the concave and convex part. The larger the valley portion that retains the lubricant, the higher the oil storage effect can be expected, and its size can be calculated based on the area (valley area) of the portion equivalent to (Pk+Pvk) of the cross-sectional profile. In addition, Pk and Pvk are respectively specified by ISO: 21920, Pk is the level difference of the core part (コア portion), and Pvk is the height of the protruding valley.

[0051] Here, in order to verify the oil storage performance of large fluctuations, the following experiment 1 was carried out.

[0052] (Experiment 1: Verification of oil storage performance under large fluctuations)

[0053] The experiment of comparing the sintering life is conducted by sliding a resin sample used as a retainer and a metal part used as a rolling element, changing the valley area representing the large undulations of the resin sample. It should be noted that the surface of the metal part is a surface shape of grinding and finishing used in general rolling elements. The valley area of ​​the resin sample is measured using a stylus-type roughness measuring machine and a non-contact white interference surface shape measuring machine. In addition, a rotary friction tester is used in the measurement of the sintering life. It should be noted that the judgment of sintering is set at the moment when the friction coefficient monitored in the test exceeds the specified value.

[0054] As the resin samples, as shown in Table 1, four types of resin samples A to D having different valley areas were used. Figure 2 The results of measuring the concavo-convex shapes of the surfaces of the resin samples are shown in FIG. Figure 2 In each graph, the vertical axis represents the depth of the valley portion (μm), and the horizontal axis represents the measurement position (mm).

[0055] in addition, Figure 3A The valley area of ​​the resin sample C is shown as an example of the calculation of the valley area. The shaded portion in the figure is the valley area, that is, (Pk+Pvk).

[0056] [Table 1]

[0057] Table 1. Texture shapes

[0058]

[0059] Here, refer to Figure 3B The calculation method of the valley area is described. Figure 3B FIG. 1 is a flow chart showing a method for calculating the valley area. Figure 3B As shown, first, the concavo-convex shape of the surface of the sample as the object is measured (step S1: surface shape measurement). Then, for the measured surface shape, a cross-sectional profile that has been subjected to tilt correction and shape removal processing is prepared (step S2: tilt correction, shape removal processing), and a load curve is prepared based on the obtained cross-sectional profile (step S3: load curve preparation). Then, Ppk, Pk, Pvk and Pmrk1 are calculated respectively according to the load curve (step S4: calculation of Ppk, Pk, Pvk, Pmrk1). Furthermore, the part of the cross-sectional profile corresponding to Pmrk1 or above is extracted (step S5: extraction of the cross-sectional profile corresponding to Pmrk1 or above), and after preparing the profile of the part corresponding to Pk+Pvk, the area of ​​the valley part is calculated, and the value is divided by the data length of the cross-sectional profile as the value per unit length, which is taken as the valley area (step S6: calculation of the valley area per unit length).

[0060] In addition, the Ppk, Pk, Pvk, and Pmrk1 shown above use parameters defined in ISO:21920.

[0061] Then, in Figure 4 In the graph, the relationship between the valley area and the sintering life is shown. The valley area and the sintering resistance (sintering life) are linearly related. The valley area is 1000 μm 2 / mm or more, indicating that resin sample A has no oil storage ( Figure 4 The sintering resistance of the resin sample A) is about 1.5 times that of the resin sample A). In addition, the valley area is 4000μm 2 / mm or more, it shows about 2.6 times, and the valley area is 5000μm 2 / mm or more, it shows about 3 times, and the valley area is 6000μm 2 / mm or more shows about 3.5 times higher sintering resistance, and excellent sintering resistance effect can be expected. On the other hand, the larger the valley area, the larger the unevenness, which may cause vibration and bad sound of the retainer. Therefore, it is considered that the maximum valley area is 20000μm 2 / mm or less.

[0062] Based on the above, it can be said that for large fluctuations, the valley area corresponding to the portion (Pk+Pvk) is 1000 μm 2 / mm or more, more preferably 4000 μm2 / mm or more, more preferably 5000 μm 2 / mm or more, more preferably 6000μm 2 / mm or more, most preferably 8000μm 2 / mm or more, and 20000μm 2 / mm or less, more preferably 15000 μm 2 / mm or less, more preferably 12000μm 2 / mm or less, most preferably 10000μm 2 Any shape below 0.1mm will do.

[0063] In addition, it is believed that the supply of lubricant to the contact surface is caused by the wetting and spreading of oil, and the speed of wetting and spreading is related to the presence or absence of fine irregularities on the surface. In the following, in Experiment 2, verification was conducted on the difference in fine roughness.

[0064] (Experiment 2: Verification of small roughness differences)

[0065] As shown in Table 2, resin samples C to C4 and D to D4 with different oil storage and micro-roughness were prepared. It should be noted that, as resin samples C2 to C4, resin samples with the same valley area as resin sample C with "medium" oil storage, which showed excellent seizure resistance in Experiment 1, were used, and the micro-roughness of each was made different. In addition, as resin samples D2 to D4, resin samples with the same valley area as resin sample D with "large" oil storage, which showed excellent seizure resistance in Experiment 1, were used, and the micro-roughness of each was made different.

[0066] The minute roughness can be expressed by the roughness RLo using a small cutoff filter, and here the RLo using λc: 0.08mm is used. In addition, "RLo" is one of the roughness standards described in ISO: 1984 and is called "extension length of the profile". Then, the portion exceeding 100% of the ratio of the length measured in the profile curve to the length of the profile is expressed in "%". In addition, in a smooth surface without bumps and depressions, it is 0%.

[0067] The surface properties of each resin sample used in the evaluation are shown in Table 2, and the relationship between the valley area and RLo (λc: 0.08 mm) of each resin sample is shown in a graph. Figure 5 and Figure 6 The “micro roughness” was determined by 3D profiling using a white interferometric surface profile measuring instrument called TALISURE CCI manufactured by AMTEC.

[0068] [Table 2]

[0069] Table 2. List of sample shapes

[0070]

[0071] Then, in the same manner as in Experiment 1, the sintering life was measured using a rotary friction tester using a metal component as a rolling element. The results are shown in Figure 7 .

[0072] like Figure 7 As shown, in the comparison of resin samples C to C4 with medium oil storage, the sintering life is the same regardless of the presence or size of the micro-roughness. On the other hand, in the comparison of resin samples D to D4 with large oil storage, it can be confirmed that in the resin sample D3 where the RLo (λc: 0.08mm) rise is observed, the sintering life is about 1.5 times that of the resin sample D with "extremely small" micro-roughness.

[0073] Figure 8 The relationship between RLo (λc = 0.08mm) and sintering life of resin samples with large oil storage is shown. They have a linear relationship. If the sintering life when RLo≈0 is calculated by extrapolation as a benchmark, it can be seen that when RLo=1%, the sintering resistance is about 1.5 times, when RLo=2%, the sintering resistance is about 2 times, when RLo=3%, the sintering resistance is about 2.5 times, when RLo=5%, the sintering resistance is about 3.5 times, and when RLo=7%, the sintering resistance is about 4.5 times.

[0074] It can be said that for minute roughness, RLo (λc: 0.08 mm) is greater than 1%, more preferably greater than 2%, further preferably greater than 3%, further preferably greater than 5%, and most preferably greater than 7%. In addition, RLo (λc: 0.08 mm) is less than 12%, more preferably less than 10%, and most preferably less than 9%, and the shape is good.

[0075] As can be seen from the above, by providing a texture with a large valley area capable of storing oil, that is, an area corresponding to (Pk+Pvk) and RLo (λc: 0.08 mm) = 1% or more indicating a micro roughness, particularly high seizure resistance can be expected.

[0076] It should be noted that the magnitude of the minute roughness parameter RLo (λc: 0.08 mm) has a limit, and it is considered that the magnitude that can be given in reality is RLo (λc: 0.08 mm) = 12% or less.

[0077] As described above, from Experiments 1 and 2, it can be seen that by giving the valley area of ​​the portion corresponding to (Pk+Pvk) to be 1000 μm 2 / mm or more, preferably 6000 μm 2 / mm or more and 20000μm 2 / mm or less and a texture with RLo (λc: 0.08 mm) of 1% to 12% can obtain high seizure resistance.

[0078] The texture is preferably an isotropic texture that can obtain the same value when measured in any direction. It is believed that by setting the texture to be isotropic, the oil storage effect and the effect of supplying the lubricant to the contact surface based on the micro-roughness can be expected to be manifested regardless of the sliding direction.

[0079] (Experiment 3: Verify that a predetermined isotropic texture is applied in all directions)

[0080] Resin samples having surface properties shown in Table 3 were prepared. The resin samples were the same as those in Experiment 2.

[0081] [Table 3]

[0082] Table 3. List of sample shapes

[0083] Resin samples oil storage Micro roughness A none none C3 middle big C4 middle Extra Large D4 big Extra Large

[0084] Then, if Fig. 9 As shown in Figure 1, for resin sample 10, RLo (λc: 0.08 mm) and valley area were measured at four locations in four directions (0°-45°, 45°, 90°) divided equally by 45°. In addition, for textures with grains, the measurement was performed with the direction perpendicular to the grains as 0° and the direction parallel to the grains as 90°. The results are shown in tables 4 to 6 and Figure 10-11 .in addition, Fig.10 represents the result of RLo, Fig.11 The results of the valley areas are shown. Table 4 shows the average values ​​of the measured values, Table 5 shows the maximum values ​​of the measured values, and Table 6 shows the minimum values ​​of the measured values.

[0085] [Table 4]

[0086] Table 4. Measurement results of RLo (λc: 0.08 mm) and valley area (average value)

[0087]

[0088] [Table 5]

[0089] Table 5. Measurement results of RLo (λc: 0.08 mm) and valley area (maximum value)

[0090]

[0091] [Table 6]

[0092] Table 6. Measurement results of RLo (2c: 0.08 mm) and valley area (minimum value)

[0093]

[0094] As shown in these results, it is found that the valley area corresponding to the portion of (Pk+Pvk) is isotropically provided in each direction is 1000 μm 2 / mm or more and 20000μm 2 / mm or less, and a texture with RLo (λc: 0.08 mm) of 1% to 12%.

[0095] It should be noted that, although the present invention has been described using rolling bearings as an example, there is no limitation on the combination of a first component with low hardness and a second component with high hardness. For example, in a combination of a metal rolling element or a ceramic rolling element in a direct-acting device and a resin spacer disposed between the metal rolling elements or between the ceramic rolling elements, a combination of a resin gear and a metal gear or a ceramic gear, etc., an isotropic texture of the surface properties specified in the present invention can be imparted to the contact portion of the resin component that contacts the metal component or the ceramic component.

[0096] Various embodiments have been described above, but the present invention is certainly not limited to these examples. As long as one skilled in the art can think of various variations or modifications within the scope described in the claims, it is obvious that these variations or modifications also belong to the technical scope of the present invention. In addition, within the scope of not departing from the gist of the invention, the various constituent elements in the above-mentioned embodiments may also be arbitrarily combined.

[0097] In addition, this application is based on the Japanese patent application (Japanese Patent Application No. 2022-154942) filed on September 28, 2022, and the contents are incorporated herein by reference.

[0098] Description of Reference Numerals

[0099] 1 Inner ring

[0100] 2 Outer ring

[0101] 3 rolling element (ball)

[0102] 4 Retainer

[0103] 5 Seals

[0104] 10 Resin samples

Claims

1. A sliding component, characterized in that: In the sliding member, a first member and a second member having a higher hardness than the first member slide with each other via a lubricant. The contact portion of the first member that contacts the second member is provided with an isotropic texture, wherein the valley area of ​​the texture is 1000 μm 2 / mm or more and 20000μm 2 / mm or less, and RLo (λc=0.08mm) is 1% or more and 12% or less.

2. The sliding component according to claim 1, wherein: The valley area is 4000 μm 2 / mm or more and 12000μm 2 / mm or less.

3. The sliding component according to claim 2, characterized in that The valley area is 6000 μm 2 / mm or more and 12000μm 2 / mm or less.

4. The sliding component according to claim 3, characterized in that The valley area is 8000 μm 2 / mm or more and 10000μm 2 / mm or less.

5. The sliding component according to any one of claims 1 to 4, characterized in that The first component is a resin component, and the second component is a metal component or a ceramic component.

6. The sliding component according to claim 5, characterized in that The first member is a resin cage of a rolling bearing, and the second member is a metal rolling element or a ceramic rolling element.

7. The sliding component according to claim 5, characterized in that The second member is a metal rolling element or a ceramic rolling element of the linear motion device, and the first member is a spacer existing between the metal rolling elements or between the ceramic rolling elements.

8. The sliding component according to claim 5, characterized in that The first member is a gear made of resin, and the second member is a gear made of metal or ceramic.

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