JP4253593B2 - Sliding surface structure and forming method of sliding member - Google Patents

Description

  The present invention relates to a structure and a method for forming a sliding surface of a sliding member such as a piston ring or a cylinder liner of an internal combustion engine, and more particularly, to one that can suppress the dropout of an embedded low friction material.

  In order to give self-lubricating properties to sliding surfaces such as piston rings and cylinder liners, a configuration has been proposed in which various low-friction materials are arranged on the sliding surface of the base material and combined. For example, Patent Document 1 discloses a structure in which a substantially cylindrical solid lubricant 320 made of graphite or the like is embedded in a sliding surface 302 of a base material 301 as shown in FIGS. 3 (a) and 3 (b). Yes. Patent Document 2 discloses a structure in which particles and whiskers of a material excellent in oil adsorption are dispersed in a base material.

Japanese Utility Model Publication No. 4-80963 Japanese Patent Laid-Open No. 7-145436

  However, in these structures, there is a problem that the low friction material embedded in the base material is easily dropped.

  Accordingly, an object of the present invention is to provide a sliding surface structure capable of suppressing the falling of the low friction material when the low friction material is disposed on the sliding surface of the base material in order to provide the sliding surface with self-lubricating properties, and It is to provide a forming method.

The first aspect of the present invention is a step of forming a low friction material layer on the surface of a base material, and a recess that removes a part of the low friction material layer and exposes a part of the base material as a sliding surface. Forming a recess in the low friction material layer at least in part with a tapered portion whose cross-sectional area decreases from the inside to the inside, forming a constraining layer in contact with the surface of the recess, and the formed Removing the surface of the constraining layer by a predetermined thickness to expose the low friction material layer .

According to the second aspect of the present invention , a low friction material layer is formed on the surface of the base material by printing to expose a part of the base material, and the taper whose cross-sectional area is reduced from the sliding surface to the inside. Forming a recess having at least a part in the low friction material layer, forming a constraining layer in contact with the surface of the recess, and removing the surface of the constraining layer formed by a predetermined thickness. And a step of exposing the low friction material layer .

According to a third aspect of the present invention , a low friction material layer is formed on the surface of a base material, and a part of the low friction material layer is removed to expose a part of the base material. A recess having at least part of a tapered portion whose cross-sectional area decreases as it goes to is formed in the low friction material layer, a constraining layer in contact with the surface of the concavity is formed, and the surface of the formed constraining layer is predetermined The sliding surface structure of the sliding member is characterized in that only the thickness is removed to expose the low friction material layer .

According to a fourth aspect of the present invention , a low friction material layer is formed on the surface of the base material by printing to expose a part of the base material, and the taper whose cross-sectional area is reduced from the sliding surface to the inside. Forming a recess having at least a portion in the low friction material layer, forming a constraining layer in contact with the surface of the recess, and removing the surface of the constraining layer by a predetermined thickness to form a low friction material The sliding surface structure of the sliding member is characterized in that the layer is exposed .

  Embodiments of the present invention will be described below with reference to the drawings. The sliding member 1 according to the first embodiment is a substantially annular piston ring, and, as shown in FIG. 1 (d), a low friction material layer 20 exposed on at least a part of the sliding surface 2, and a sliding member. And a constraining layer 30 that adheres to the base material 10 of the moving member 1 and contacts the low friction material layer 20 to restrain the low friction material layer 20 in the normal direction of the sliding surface 2 from the outside. Further, the overall shape of the low friction material layer 20 is a retaining shape or a reverse taper shape in which the cross-sectional area increases from the sliding surface 2 toward the inside.

  A method for forming the sliding surface 2 of the sliding member 1 according to the first embodiment is as follows. In FIG. 1A, first, the low friction material layer 20 is formed on the sliding surface 2 of the base material 10 made of steel.

For this low friction material layer 20, for example, a solid lubricant such as molybdenum disulfide (MoS ₂ ) or PTFE (tetrafluoroethylene) is dispersed and held in a resin material such as polyamide, phenol, polyimide, etc. The formed slurry is formed by applying the slurry to the sliding surface 11 of the base material 10 and firing the slurry. The film thickness of the low friction material layer 20 is preferably about several μm to 10 μm. In such a low-friction material layer 20, the resulting coating is soft and slightly inferior in wear resistance, but a low friction coefficient can be maintained by the solid lubricant or resin material remaining on the sliding surface. is there.

  Next, as shown in FIG. 1B, a plurality of recesses 21 are formed on the surface of the low friction material layer 20 by cutting using a cutting tool. The recess 21 is a spiral or annular streak formed in the circumferential direction over the entire circumference of the outer peripheral surface of the sliding member 1 that is a piston ring. The depth of the recess 21 is set to such a depth that a part of the base material 10 is exposed at the bottom of the recess 21. The width of the recess 21 is about 0.1 mm, and the depth of the recess 21 is about 10 μm. Further, the cross-sectional shape of the recess 21 is a shape in which the cross-sectional area is reduced from the surface of the sliding surface 2 toward the inside, that is, a draft gradient. As a result of such cutting, the shape of the low-friction material layer 20 is formed into a retaining shape or a reverse taper shape in which the cross-sectional area increases from the surface of the sliding surface 2 toward the inside.

  Next, as shown in FIG. 1C, a constraining layer 30 made of a wear-resistant material is formed so as to cover the entire sliding surface 2 including the recess 21. For example, a ceramic-based thermal spray material such as alumina, chromia, or zirconia is used as the wear-resistant material constituting the constraining layer 30, and the formation thereof is performed by, for example, plasma spraying. In this case, it is possible to form a thick film with a film thickness of about several tens of μm to several hundreds of μm, but the coating surface has a surface roughness of about several μm to 20 μm Rz, and grinding and polishing processing is required.

  Next, as shown in FIG. 1 (d), the surface of the constraining layer 30 is lapped with a lapping machine to remove the surface of the constraining layer 30 by a predetermined thickness, and the low friction material layer 20 is removed. Expose. By such a cutting process, the low friction material layer 20 and the constraining layer 30 are present on the outermost surface of the sliding surface 2, and both are alternately distributed. In addition, since the sliding member 10 of this embodiment is a piston ring, the cutting process for creation of a joint is performed after the above process.

  In the sliding member 1 formed as described above, since the low friction material layer 20 and the constraining layer 30 exist on the outermost surface of the sliding surface 2, the self-lubricating property of the low friction material layer 20 and the constraint Both the wear resistance of the layer 30 can be imparted to the sliding surface 2. Further, since the constraining layer 30 is provided separately from the base material 10, the low friction material layer or the solid lubricant is applied to the surface of the base material 10 as compared with the structure in which the solid lubricant is simply dispersed in the base material. It can be aligned correctly.

  In addition, the shape of the low friction material layer 20 is formed as a retaining shape or a reverse taper shape in which the cross-sectional area increases as it goes from the surface of the sliding surface 2 to the inside, and the constraining layer 30 is formed on the outside thereof. 30 adheres to the base material 10 and interferes with the low friction material layer 20 from the outside (that is, when the low friction material layer 20 tries to move in the peeling direction, the compressive stress of the constraining layer 30 causes the sliding surface 2 The low-friction material layer 20 is constrained by the constraining layer 30. Such restraint by the constraining layer 30 can be rephrased as an action of the constraining layer 30 gradually increasing the stress in the same manner as the wedge or dovetail groove when the low friction material layer 20 tries to move in the peeling direction. As described above, in this embodiment, the adhesive force between the base material 10 and the constraining layer 30 can contribute to the constraining of the low friction material layer 20, and the adhesiveness or peeling between the base material 10 and the low friction material layer 20. Even if the strength is small, the low friction material layer 20 can be suitably prevented from falling off.

  Further, in this embodiment, the shape of the recess 21 is a tapered shape whose cross-sectional area decreases as it goes from the sliding surface 2 to the inside. Therefore, when this is formed from the outside, the formation is easy. By forming the constraining layer 30 so as to be in contact with the surface of 21, a structure in which the low friction material layer 20 is geometrically constrained can be easily formed.

  Further, in this embodiment, since the concave portion 21 is formed with the circumferential direction of the sliding member 1 as the longitudinal direction, the shape of the low friction material layer 20 after the formation is also the sliding direction when the sliding member 1 is used. The direction substantially perpendicular to the middle and up and down directions can be the longitudinal direction, and the drop-off can be suitably suppressed.

  Next, a second embodiment will be described. Similarly, the sliding member 101 according to the second embodiment is a piston ring, and as shown in FIG. 2E, a low friction material layer 120 exposed on at least a part of the sliding surface 102, and a base material. And a constraining layer 130 for constraining the low friction material layer 120 in the normal direction of the sliding surface 102 from the outside by adhering to the low friction material layer 120. The overall shape of the low friction material layer 120 is an inversely tapered shape in which the cross-sectional area increases from the surface of the sliding surface 102 to the inside.

  A method for forming the sliding surface 102 of the sliding member 101 according to the second embodiment is as follows. In FIG. 2A, first, a plurality of substantially arc-shaped cross-sections 103 are formed on a sliding surface 102 of a base material 110 made of steel by cutting using a cutting tool. The low friction material layer 120 is formed so as to cover it. The material and coating method of the low friction material layer 120 are the same as those of the low friction material layer 20 in the first embodiment.

  Next, as shown in FIG. 2 (b), the surface of the low friction material layer 120 is lapped by a lapping machine to remove the surface of the low friction material layer 120 by a predetermined thickness. To flatten. This step may be omitted.

  Next, as shown in FIG. 2C, a plurality of concave portions 121 having a substantially arc-shaped cross section are formed on the surface of the low friction material layer 120 by cutting using a cutting tool. The recess 121 is a spiral or annular streak formed in the circumferential direction over the entire circumference of the outer peripheral surface of the sliding member 101 which is a piston ring, and the previously formed streak 103 is the vertical direction in the figure. It is formed at an offset position so as not to coincide with each other. The depth of the recess 121 is set such that a part of the base material 110 is exposed at the bottom of the recess 121. The width of the recess 121 is about 0.1 mm, and the depth of the recess 121 is about 10 μm. Further, the cross-sectional shape of the recess 121 is a shape in which the cross-sectional area is reduced from the surface of the sliding surface 102 toward the inside, that is, a draft gradient. As a result of such a cutting process, the shape of the low friction material layer 120 is formed in a retaining shape or a reverse taper shape in which the cross-sectional area increases from the surface of the sliding surface 102 to the inside.

  Next, as shown in FIG. 2 (d), a constraining layer 130 made of an abrasion resistant material is formed so as to cover the entire sliding surface 102 including the recess 121. The material and coating method of the constraining layer 130 are the same as those of the constraining layer 30 in the first embodiment.

  Next, as shown in FIG. 2 (e), the surface of the constraining layer 130 is lapped by a lapping machine to remove the surface of the constraining layer 130 by a predetermined thickness, and the low friction material layer 120 is removed. Expose. By such a cutting process, the low friction material layer 120 and the constraining layer 130 are present on the outermost surface of the sliding surface 102, and both are alternately distributed.

  In the sliding member 101 formed as described above, since the low friction material layer 120 and the constraining layer 130 are present on the outermost surface of the sliding surface 102, the low friction material layer is the same as in the first embodiment. Both the self-lubricating property of 120 and the wear resistance of the constraining layer 130 can be imparted to the sliding surface 102.

  Further, in this embodiment, the shape of the low friction material layer 120 is formed as a retaining shape or a reverse tapered shape whose cross-sectional area increases as it goes from the surface of the sliding surface 102 to the inside, and the constraining layer 130 is formed on the outside thereof. Therefore, the constraining layer 130 adheres to the base material 110 and interferes with the low friction material layer 120 from the outside, whereby the low friction material layer 120 is constrained by the constraining layer 130. Therefore, in the present embodiment, the adhesive force between the base material 110 and the constraining layer 130 can contribute to the constraining of the low friction material layer 120, and the adhesion or peel strength between the base material 110 and the low friction material layer 120 is high. Even if it is small, the dropout of the low friction material layer 120 can be suitably suppressed.

  Further, in this embodiment, the shape of the recess 121 is a tapered shape whose cross-sectional area decreases as it goes from the sliding surface 102 to the inside. Therefore, when this is formed from the outside, the formation is easy. By forming the constraining layer 130 so as to contact the surface of 121, a structure in which the low friction material layer 120 is geometrically constrained can be easily formed.

  In each of the above embodiments, the overall shape of the recesses 21 and 121 is a tapered shape whose cross-sectional area decreases from the sliding surfaces 2 and 102 to the inside, but the recesses in the present invention are from the sliding surfaces. As long as at least a part of the taper part whose cross-sectional area decreases toward the inside is provided, a corresponding part of the constraining layer covered by the confined part can have a shape (that is, constraining). The layer 30 can be made to contact the low friction material layer 20 from the outside in the normal direction of the sliding surface 2 so that the low friction material layer 20 is constrained. Obtainable. In addition, the shape of the recess in the present invention is not only a skewed shape in which the cross-sectional area is linearly or continuously decreasing like the recesses 21 and 121 in each of the above embodiments, but also a stepped shape or a screw in which the cross-sectional area decreases discretely Various shapes such as mountain shapes can be arbitrarily adopted.

  In addition, even when the concave portion in the present invention does not have a tapered portion whose cross-sectional area decreases as it goes from the sliding surface to the inside, according to the forming method of the present invention, a fine restraint structure can be easily formed, In addition, the expected effect of suppressing the dropout of the low friction material layer can be obtained to a considerable extent by expanding the material interface area per volume.

  Further, in each of the above embodiments, the recesses 21 and 121 are formed as streak and formed by cutting using a cutting tool. However, the recess in the present invention is not limited to the streak shape, for example, a dimple shape or the like. It may be scattered. The method for forming the recesses is not limited to cutting, and may be printing, resin molding using a mold, engraving by laser, or etching by chemical action when forming the low friction material layer. When printing is used to form the low-friction material layer, the formation of the low-friction material layer and the formation of the recesses can be performed simultaneously by using, for example, a silk screen or a stencil. Moreover, the surface removal process of the constraining layer shown in FIGS. 1D and 2E can also be performed by a method other than cutting.

  In each of the above embodiments, the low-friction material layers 20 and 120 are formed by applying and baking a resin material containing a fixed lubricant. However, the low-friction material in the present invention includes other various materials. It can be selected and its formation method is arbitrary. For example, DLC (Diamond-Like Carbon), which is known as a material with low friction and excellent wear resistance, may be used as the material of the low friction material layer. The formation is performed by PVD (Physical Vapor Deposition) or CVD (Chemical Vapor Deposition) such as plasma CVD. With DLC, a hard film having a thickness of about several μm and an HV (Vickers hardness) of 1000 or more can be obtained, and high wear resistance and high smoothness that does not require post-processing can be obtained.

  In addition, as the wear resistant material constituting the constraining layers 30 and 130 in the present invention, various materials other than those listed in the above embodiments can be selected, and the formation method thereof is arbitrary, and other than the ceramic type. A thermal spray material, that is, a cermet-based or metal-based thermal spray material may be used, and a hard coating can be formed particularly with ceramic-based and cermet-based thermal spray materials. For the cermet-based sprayed material, high-speed flame spraying such as HVOF (High Velocity Oxy-Fuel) is used, and the WC-Co-based material is particularly suitable.

  In addition, a hard film made of a nitride such as TiN or CrN, a carbide such as TiC or SiC, or a composite carbonitride such as TiCN can be used as an abrasion resistant material. It can be performed by ion plating. For example, when a TiN or CrN film is formed on a steel substrate at a film forming temperature of 350 ° C. to 550 ° C. by arc ion plating, even if the film thickness is about 0.1 μm to several μm, the TiN film is HV2000. A very hard constraining layer of about HV1400 can be formed with a CrN film, and sufficient wear resistance as a machine part can be obtained (however, the CrN film can be formed to a thickness of 10 μm or more). In addition, various other PVDs such as sputtering, and also CVD can be used to form the wear resistant material.

  In each of the above embodiments, the sliding member is a piston ring. However, in the present invention, various engine parts such as a cylinder liner and a piston skirt, and various mechanical devices and machine elements that require lubrication such as a bearing are slid. It can be widely applied to members.

(A) thru | or (d) are sectional drawings which show the sliding face structure of the sliding member which concerns on 1st Embodiment of this invention, and its formation method. (A) thru | or (e) are sectional drawings which show the sliding face structure of the sliding member which concerns on 2nd Embodiment of this invention, and its formation method. An example of the conventional sliding surface structure is shown, (a) is the sectional view, and (b) is the front view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,101 Sliding member 2,102 Sliding surface 10,110 Base material 20,120 Low friction material layer 21,121 Concavity 30,130 Constraining layer

Claims (4)

Forming a low friction material layer on the surface of the base material;
Removing a part of the low-friction material layer to expose a part of the base material, the recessed part having at least a tapered part whose cross-sectional area decreases from the sliding surface to the inside ; Forming the low friction material layer;
Forming a constraining layer in contact with the surface of the recess;
Removing the surface of the formed constraining layer by a predetermined thickness to expose the low friction material layer;
The sliding surface forming method of the sliding member containing this. By forming a low-friction material layer on the surface of the base material by printing, it is a concave portion that exposes a part of the base material, and has at least a tapered portion whose cross-sectional area decreases as it goes from the sliding surface to the inside. Forming a recess in the low friction material layer;
Forming a constraining layer in contact with the surface of the recess;
Removing the surface of the formed constraining layer by a predetermined thickness to expose the low friction material layer;
The sliding surface forming method of the sliding member containing this. A low friction material layer is formed on the surface of the base material,
Removing a part of the low-friction material layer to expose a part of the base material, the recessed part having at least a tapered part whose cross-sectional area decreases from the sliding surface to the inside; Formed in a low friction material layer,
Forming a constraining layer in contact with the surface of the recess,
A sliding surface structure of a sliding member, wherein the surface of the formed constraining layer is removed by a predetermined thickness to expose a low friction material layer. By forming a low-friction material layer on the surface of the base material by printing, it is a concave portion that exposes a part of the base material, and has at least a tapered portion whose cross-sectional area decreases as it goes from the sliding surface to the inside. Forming a recess in the low friction material layer;
Forming a constraining layer in contact with the surface of the recess,
A sliding surface structure of a sliding member, wherein the surface of the formed constraining layer is removed by a predetermined thickness to expose a low friction material layer.

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