JP2008095722A - Sliding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sliding method having a high reducing effect of a friction coefficient. <P>SOLUTION: The sliding method provided for sliding a first member 11 and a second member 11 through a viscous fluid is constituted to slide the first member having fine recessed part 13 formed on a sliding surface with the second member so that the absolute value of moving speed of the first member is larger than the absolute value of moving speed of the second member when a contact part between the first member and the second member is viewed from a fixed coordinate system. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sliding method for sliding a first member and a second member through a viscous fluid.

  In order to reduce friction when sliding the first member and the second member through a viscous fluid such as a lubricating oil, a concave portion such as a fine depression or groove is formed on the sliding surface. (See Patent Documents 1 and 2). The formation of the concave portion is expected to have an effect of oil sump by the concave portion, control of oil flow in the contact portion by the concave portion, or an effect of micro dynamic pressure by the concave portion.

The technology for forming such fine recesses is applied, for example, to reduce the friction between the rotating and sliding crankpin and the bearing metal, and to reduce the friction between the reciprocatingly sliding piston ring and the bore. Has been.
JP 2002-213612 A JP 2002-235852 A

  Although it is possible to reduce friction by forming fine concave portions, further reduction of friction is required. Further, in the conventional sliding method, there is no mention as to which fine concave portion should be formed on the moving side or fixed side member.

  Therefore, an object of the present invention is to provide a sliding method having a high friction reducing effect.

The present invention according to claim 1, which achieves the above object, comprises a sliding method of sliding the first member and the second member through a viscous fluid.
When the first member in which a fine recess is formed on the sliding surface with the second member is viewed from a coordinate system in which a contact portion between the first member and the second member is fixed, the first member The sliding method is characterized in that sliding is performed such that the absolute value of the moving speed of the second member becomes larger than the absolute value of the moving speed of the second member.

  According to the present invention, when the first member in which the fine recess is formed is viewed from the coordinate system in which the contact portion between the first member and the second member is fixed, the absolute value of the moving speed of the first member is the first value. Since the sliding is performed so as to be larger than the absolute value of the moving speed of the two members, it is possible to provide a sliding method that is highly effective in reducing friction and excellent in wear resistance and seizure resistance.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1A is a diagram schematically showing a form in which the first and second members 11 and 12 that slide in rotation are in contact with each other, and FIG. 1B shows the first and second sliding in a reciprocating manner. It is a figure which shows typically the form with which members 11 and 12 contact.

  The sliding method according to the present invention is a sliding method in which the first member 11 and the second member 12 are slid through lubricating oil as a viscous fluid. 13 is viewed from a coordinate system in which the contact portion between the first member 11 and the second member 12 is fixed, the absolute value of the moving speed of the first member 11 is It is slid so as to be larger than the absolute value of the moving speed. In other words, focusing on the point of “which side of the first member 11 and the second member 12 should the fine concave portion 13 be formed”, “the contact between the first member 11 and the second member 12”. When viewed from the coordinate system in which the portion is fixed, the fine concave portion 13 is formed in the first member 11 on the high-speed movement side. ” When viewed from the coordinate system in which the contact portion is fixed, by forming the recess 13 in the first member 11 on the high-speed movement side, the oil film thickness is smaller than when forming the recess 13 on the second member 12 on the low-speed movement side. As a result, the coefficient of friction can be reduced. Therefore, the effect of reducing friction is high, and the effects of excellent wear resistance and seizure resistance are obtained.

  Referring to FIGS. 1A and 1B, “when the contact portion between the first member 11 and the second member 12 is viewed from a fixed coordinate system, the first member 11 on the high-speed movement side has a fine recess. Will be described.

  FIG. 1A shows a form in which rotating and sliding members are in contact with each other, such as between a shaft 111 and a bearing metal 112 that rotatably holds the shaft 111. In the case of such a contact form, the point A in the drawing of the bearing metal 112 is always in contact with the shaft 111. Therefore, “when viewed from the coordinate system in which the contact portion is fixed, the minute concave portion 13 is formed in the member on the high-speed movement side” means that the minute concave portion 13 is formed in the shaft 111. Therefore, in this case, the shaft 111 corresponds to the first member 11, and the bearing metal 112 corresponds to the second member 12.

  Specific examples of the members that rotate and slide include a crank pin and a bearing metal. When the present invention is applied to this combination, the crank pin corresponds to the first member 11, the bearing metal corresponds to the second member 12, and the minute recess 13 is formed in the crank pin. By forming the recess 13 in the crank pin, the oil film thickness can be increased as compared with the case where the recess 13 is formed in the bearing metal, and a sliding method that can sufficiently exhibit the friction reducing effect can be provided.

  FIG. 1B shows a form in which reciprocating members are in contact with each other, such as between the plate 121 and the ring 122. In the case of such a contact form, the point B in the figure of the ring 122 is always in contact with the plate 121. Therefore, “when viewed from the coordinate system in which the contact portion is fixed, the minute concave portion 13 is formed in the member on the high speed movement side” means that the minute concave portion 13 is formed in the plate 121. Therefore, in this case, the plate 121 corresponds to the first member 11 and the ring 122 corresponds to the second member 12.

  Specific examples of the reciprocating members include a bore and a piston ring. When the present invention is applied to this combination, the bore corresponds to the first member 11, the piston ring corresponds to the second member 12, and the fine recess 13 is formed in the bore. By forming the recess 13 in the bore, it is possible to provide a sliding method in which the oil film thickness is increased and the friction reducing effect can be sufficiently exhibited as compared with the case where the recess 13 is formed in the piston ring.

  The second member 12 is preferably stationary. By making the sliding surface of the second member 12 opposite to the first member 11 formed with the fine recesses 13 stationary, the effect of increasing the oil film thickness is increased, and a more excellent friction reducing effect is obtained. Because you can.

  The direction of the moving speed of the first member 11 and the direction of the moving speed of the second member 12 are preferably the same. This is because by making the moving speed directions of the first and second members 11 and 12 the same, the effect of increasing the oil film thickness is increased, and a more excellent friction reducing effect can be obtained.

  There is no restriction | limiting in particular in the material of the 1st member 11 and the 2nd member 12, A various material is used according to a use. For example, in a sliding member for an internal combustion engine having a piston and a cylinder, it is desirable that the sliding member be made of a metal such as iron or aluminum. Moreover, there is no restriction | limiting in particular about a shape, The sliding member of all shapes can be employ | adopted.

  The ratio h / t of the recess 13 formed in the first member 11 is 0, where t is the depth, and h is the oil film thickness (corresponding to the viscous fluid film thickness) when sliding. It is desirable that it be formed to be 0.04 or more and 5 or less. When the ratio h / t is smaller than 0.04, a sufficient oil film cannot be secured and metal contact occurs, so that not only the friction reduction effect is not sufficiently exhibited, but also the friction coefficient may increase. On the other hand, if the ratio h / t exceeds 5, the oil film thickness h is too large with respect to the depth t of the recess 13, so that the dynamic pressure effect cannot be sufficiently exhibited, and the friction reducing effect may not be sufficiently exhibited. Therefore, when the ratio h / t is set to 0.04 or more and 5 or less, the friction reduction effect can be effectively expressed.

  As for the recessed part 13, it is desirable that the occupation area rate of the recessed part 13 in a sliding surface is 0.5% or more and 10% or less. When the occupied area ratio is smaller than 0.5%, the ratio of the concave portions 13 is too small, so that the dynamic pressure effect cannot be sufficiently exhibited, and the friction reducing effect may not be sufficiently exhibited. On the other hand, if it exceeds 10%, the ratio of the flat end portion is relatively reduced, so that the load capacity is reduced. As a result, direct contact between the metals occurs, and the friction reducing effect is not sufficiently exhibited. Friction may increase. Moreover, there is a concern that the wear resistance and the seizure resistance are also lowered. Therefore, an excellent friction reducing effect can be obtained by setting the occupied area ratio of the recess 13 to 0.5% or more and 10% or less.

  It is desirable that the recess 13 has a maximum diameter of 500 μm or less. If it exceeds 500 μm, the size of the recess 13 with respect to the contact surface is too large. For example, at the entrance, oil flows backward through the recess 13 to promote metal contact. As a result, the coefficient of friction increases. There is a fear. Therefore, since the size of the concave portion 13 on the contact surface is optimized by setting the concave portion 13 to a maximum diameter of 500 μm or less, a friction reducing effect can be effectively exhibited.

  2A is a perspective view showing the recess 13 formed on the sliding surface, and FIG. 2B is a cross-sectional view taken along line 2B-2B of FIG. 2A.

  Referring to FIG. 2, the shape of the recess 13 is the length from the front side of the slip direction 21 to the position 17 indicating the extreme value of the bottom surface of the recess 13 in the cross-sectional shape of the recess 13 in the slide direction 21. When S is S, it is desirable that S / L is 0.2 or less. The symbol t in FIG. 2 indicates the depth of the recess 13. If S / L exceeds 0.2, the oil flow on the wall surface of the recess 13 does not act effectively, so that the dynamic pressure effect is not sufficiently obtained and the friction reducing effect is not sufficiently exhibited. Therefore, when S / L is 0.2 or less, the dynamic pressure effect is sufficiently exhibited, and an excellent friction reducing effect is obtained.

  As shown in FIG. 2A, the shape of the recess 13 is preferably flat in a direction 22 orthogonal to the sliding direction 21. The shape flat in the direction 22 orthogonal to the sliding direction 21 is a shape in which the maximum length in the orthogonal direction 22 is larger than the maximum length in the sliding direction 21. The flat shape is not limited to a rectangle, and may be an elliptical shape, a polygonal shape, or a circular shape. Since the shape of the recess 13 is flat in the orthogonal direction 22, a large amount of lubricating oil can be caused to flow into the sliding portion, and friction can be reduced.

  The above-described first and second members 11 and 12 are preferably used for sliding portions of an internal combustion engine or a transmission. By applying the first and second members 11 and 12 that exhibit a sufficient friction reduction, it is possible to reduce the friction in the sliding portion of the internal combustion engine or the transmission, and to reduce the wear resistance and resistance of the sliding portion. The seizure property can be improved.

(Example)
The friction reducing effect was confirmed by two types of tests, an inscribed two-cylinder test and a piston ring / bore simulation test.

  FIG. 3 is a perspective view showing the inscribed two-cylinder testing machine 30 with a part cut away, and FIGS. 4A to 4D are cross-sectional views showing the cross-sectional shape of the recess 13 formed on the sliding surface. 5-8 is a top view which shows the arrangement | positioning form of the recessed part 13 on the sliding surface in Examples 1-7.

  The inscribed two-cylinder test was performed in order to confirm the effect of reducing friction between members that slidably rotate, such as between a crankpin and a bearing metal. Referring to FIG. 3, the inscribed two-cylinder testing machine 30 includes an inner cylinder 31 and an outer cylinder 32 that slide through a lubricating oil 33 as a viscous fluid. In the contact region 34 indicated by a dotted line in the figure, the outer surface of the inner cylinder 31 and the inner surface of the outer cylinder 32 are in sliding contact. An arrow W in the figure indicates a radial load acting on the inner cylinder 31.

  The outer cylinder 32 is obtained by press-fitting aluminum metal having an inner diameter of 45 mm into a steel cylinder having an outer diameter of 60 mm. On the other hand, the inner cylinder 31 is a quenching and tempering material of steel (SCM440H steel) having an outer diameter of φ43 mm.

  An AC servomotor (not shown) is attached to each of the inner cylinder 31 and the outer cylinder 32 so that the rotation can be controlled independently. Then, an oil film was formed between the inner cylinder 31 and the outer cylinder 32 by immersing the inner cylinder 31 and the outer cylinder 32 in an oil bath containing 5 W 30 of oil.

  In the experiment, a radial load of 20 kg, an oil temperature of 80 ° C., a relative sliding speed of 6 m / s, an average speed of 2 m / s, a rotational torque is measured by a torque sensor attached to the inner cylindrical shaft, and a tangential force is calculated. The coefficient of friction was determined by dividing by.

  In Examples 1 to 7, the recess 13 was formed only on the outer surface of the inner cylinder 31. In each of Examples 1 to 7, (1) Friction coefficient μ1 when the inner cylinder 31 formed with the recess 13 is rotated and the outer cylinder 32 is fixed, that is, when the recess 13 is formed on the moving member, (2 ) When the inner cylinder 31 formed with the recess 13 is fixed and the outer cylinder 32 is rotated, that is, when the recess 13 is formed on the fixed member, (3) Both the inner cylinder 31 and the outer cylinder 32 Were measured in the same direction to measure the friction coefficient μ3 when the inner cylinder 31 was rotated so that the moving speed of the inner cylinder 31 was larger than the moving speed of the outer cylinder 32. In each of the first to seventh embodiments, the friction coefficient ratio α (μ1 / μ2) when the concave portion 13 is formed on the moving member with respect to the concave portion 13 formed on the fixed member, the inner cylinder 31 and the outer cylinder 31 The friction coefficient ratio β (μ1 / μ3) when the outer cylinder 32 was stationary with respect to the case where both the cylinders 32 were rotated was obtained.

  The concave fine shape was formed by mask blasting. In mask blasting, optical lithography technology is used to form a concave fine shape on a resin mask, the resin mask is affixed to the outer surface of the inner cylinder 31, and then ceramic particles having an average particle diameter of 25 μm are applied to the projection nozzle. Were projected under the condition of a projection pressure of 0.5 MPa to obtain a concave fine shape. After forming the fine shape of the concave portion, the bulge of the edge portion formed around the concave shape was removed with a tape wrap film having a particle size of 9 μm and used for the test. The depth of the recess 13 was 3 μm.

  The cross-sectional shape of the recess 13 includes a semicircular arc shape (FIG. 4A), a rectangular shape (FIG. 4B), a two-row triangular shape (FIG. 4C), and a triangular shape (FIG. 4D). did. In Table 1 below, the cross-sectional shape is represented by the symbols “U”, “R”, “W4”, and “T3”.

  As for the arrangement form of the recesses 13, the zigzag arrangement (FIG. 5 (A)) in the first embodiment, the zigzag arrangement (FIG. 5 (B)) in the second embodiment, the hexagon arrangement (FIG. 6 (A)) in the third embodiment, Example 4 is a houndstooth arrangement (FIG. 6B), Example 5 is a houndstooth arrangement (FIG. 7A), and Example 6 is a houndstooth arrangement (FIG. 7B). 7 is a houndstooth arrangement (FIG. 8).

  The experimental results are shown in Table 1 below.

  As shown in Table 1, the friction coefficient ratio α in the case where the concave portion 13 is formed in the moving member with respect to the case where the concave portion 13 is formed in the fixed member is smaller than 1 in any case. The effect of the present invention was confirmed that the oil film thickness can be increased and the friction can be reduced by forming the recess 13 in the moving member rather than forming the recess 13 in the fixed member. Further, the friction coefficient ratio β when the outer cylinder 32 is stationary with respect to the case where both the inner cylinder 31 and the outer cylinder 32 are rotated is smaller than 1 in any case. The effect of the present invention that the oil film thickness can be increased and friction can be reduced by resting the member opposite to the member on which the recess 13 is formed was confirmed.

  FIG. 9 is a perspective view showing the piston ring / bore simulation test machine 40, and FIG. 10 is a view showing the arrangement of the recesses 13.

  The piston ring / bore simulation test was performed in order to confirm the effect of reducing friction between the reciprocating members such as between the piston ring and the bore. Referring to FIG. 9, the piston ring / bore simulation tester 40 includes a ring 41 and a plate 42 that slide through lubricating oil as a viscous fluid. In the experiment, the ring 41 was fixed and only the plate 42 was slid back and forth. The double arrow in the figure indicates the sliding direction 21 and the single arrow indicates the load direction. The reciprocating sliding motion was performed by converting the rotational motion into the reciprocating motion using a crank mechanism. The sliding distance, that is, the length H along the sliding direction 21 was 30 mm per process. The width B of the contact portion between the ring 41 and the plate 42 was 40 mm.

  As a material for the ring 41, an SCM435 carburizing and tempering material was used. The tip of the ring 41 was formed in an arc shape with a curvature radius of 30 mm. The surface of 30 mm radius was Cr plated with 100 μm, and the sliding surface of the ring 41 was finished with an arithmetic average roughness Ra of 0.2 μm. On the other hand, a plate material of austenitic cast iron (FCA) having a thickness of 40 mm × 60 mm × 5 mm was used as the material of the plate 42. The roughness of the flat part was finished to Ra 0.05 μm or less.

  In the experiment, the pressing load was 250 N, the sliding distance per reciprocation was 30 mm, the sliding speed was 600 times / min, and 5 W30 oil (oil supply temperature 25 ° C.) was dropped onto the sliding surface at 0.8 cc / min. I went. Using a load cell attached to the ring 41, the load of the shear force component was detected, and the friction coefficient was obtained by dividing by the pressing load.

  In Examples 8 and 9, a concave concave shape was formed on the plate 42 on the moving side. The occupation area ratio of the recess 13 was 2.5% in Example 8 and 5% in Example 9.

  In Comparative Example 1, a concave concave shape was formed on the ring 41 on the fixed side. The occupation area ratio of the recess 13 was set to 5%. In Comparative Example 2, no recess is formed in either the ring 41 or the plate 42. The concave portions 13 were regularly arranged in a rectangular pattern with a size of 80 × 320 μm (see FIG. 10).

  The concave fine shape was formed by mask blasting. In mask blasting, optical microlithography is used to form a concave fine shape on a resin mask, and after the resin mask is attached to a plate or ring surface, alumina abrasive grains having an average particle diameter of 20 μm are applied from a projection nozzle. The distance to the workpiece was set to 100 mm, and projection was performed under the conditions of a projection flow rate of 100 g / min and a projection pressure of 0.4 MPa to obtain a concave fine shape. After forming the fine shape of the concave portion, the bulge of the edge portion formed around the concave shape was removed with a tape wrap film having a particle size of 9 μm and used for the test. The depth of the recess 13 was 3 μm.

  The experimental results are shown in Table 2 below.

  As shown in Table 2, the ratio of the friction coefficients of Examples 8 and 9 to the friction coefficient of Comparative Example 1 is smaller than 1 in any case. Although the friction reduction effect can be obtained even when the concave portion 13 is formed in the fixed side member (ring 41) from Comparative Examples 1 and 2, as in the case of the inscribed two-cylinder test, the fixed side member ( The effect of the present invention that the oil film thickness is increased and the friction can be further reduced by forming the recess 13 in the member (plate 42) on the moving side rather than forming the recess 13 in the ring 41) was confirmed.

FIG. 1A is a diagram schematically showing a form in which the first and second members that are rotating and sliding contact each other, and FIG. 1B is a diagram in which the first and second members that are reciprocatingly sliding are illustrated. It is a figure which shows typically the form which contacts. 2A is a perspective view showing a recess formed in the sliding surface, and FIG. 2B is a cross-sectional view taken along line 2B-2B in FIG. 2A. FIG. 3 is a perspective view showing a part of the inscribed two-cylinder testing machine. 4A to 4D are cross-sectional views showing the cross-sectional shape of the recesses formed on the sliding surface. 5A and 5B are plan views showing the arrangement of the recesses on the sliding surface in Examples 1 and 2. FIG. 6A and 6B are plan views showing the arrangement of the recesses on the sliding surface in Examples 3 and 4. FIG. FIGS. 7A and 7B are plan views showing the arrangement of the recesses on the sliding surface in Examples 5 and 6. FIG. In Example 7, it is a top view which shows the arrangement | positioning form of the recessed part on a sliding surface. It is a perspective view which shows a piston ring / bore simulation tester. It is a figure which shows the arrangement | positioning form of a recessed part.

Explanation of symbols

11 first member,
12 Second member,
13 recess,
17 Position indicating the extreme value of the bottom of the recess,
21 Sliding direction,
30 Inscribed 2 cylinder testing machine,
31 inner cylinder,
32 outer cylinder,
33 Lubricating oil,
40 Piston ring / bore simulation tester,
41 rings,
42 plates,
111 shaft (first member),
112 bearing metal (second member),
121 plate (first member),
122 Ring (second member).

Claims (7)

In the sliding method of sliding the first member and the second member through the viscous fluid,
When the first member in which a fine recess is formed on the sliding surface with the second member is viewed from a coordinate system in which a contact portion between the first member and the second member is fixed, the first member A sliding method characterized by sliding so that the absolute value of the moving speed of the second member becomes larger than the absolute value of the moving speed of the second member.   The sliding method according to claim 1, wherein the second member is stationary.   The sliding method according to claim 1 or 2, wherein the direction of the moving speed of the first member and the direction of the moving speed of the second member are the same.   The ratio of h / t is 0.04 or more and 5 or less, where t is the depth of the recess and h is the thickness of the viscous fluid film during sliding. 4. The sliding method according to any one of 3 above.   The sliding method according to any one of claims 1 to 4, wherein the recessed portion has an area ratio of the recessed portion on the sliding surface of 0.5% or more and 10% or less.   The sliding method according to claim 1, wherein the recess has a maximum diameter of 500 μm or less.   In the cross-sectional shape of the concave portion in the sliding direction, when the length of the outermost surface is L and the length from the front side of the sliding direction to the position showing the extreme value of the bottom surface of the concave portion is S, S / L is 0.2 or less. The sliding method according to claim 1, wherein the sliding method is provided.

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