JP6545781B2 - Sliding bearing - Google Patents

Description

  The present invention relates to a slide bearing, and more particularly to a slide bearing in which a resin layer mainly composed of polyethylene resin is formed by injection molding on a sliding surface of a metal base material.

  As a slide bearing for use in office equipment, medical instruments, food machines and other general machines, one having a resin layer formed on a sliding surface of a base material such as sintered metal has been proposed. For example, a sintered metal is used as a bearing outer peripheral portion, and a resin material is insert-molded in a sliding portion of the bearing outer peripheral portion to form a resin layer, and at least the resin layer is in contact with the surface of the bearing outer peripheral portion A fine recess is provided on the surface of the bearing outer peripheral portion, and (the linear expansion coefficient of the resin material) × (thickness of the resin layer) in the resin layer is 0.15 or less, and the total apparent area occupied by the recess is There is known a high precision sliding bearing in which the area of the surface portion of the bearing outer peripheral portion in contact with the resin layer is 25 to 95% (see Patent Document 1). This high precision slide bearing is excellent in lubricity while having high precision because dimensional change due to temperature change of the resin layer can be suppressed. In addition, since the resin layer is formed on the sliding portion, the attack on the soft counterpart and the generation of the abnormal noise are suppressed. Furthermore, since the resin layer enters the fine recesses, the anchor effect improves the adhesion between the bearing outer peripheral portion and the resin layer.

  In addition, in order to prevent deterioration of bearing performance due to gate marks at the time of injection molding, in a slide bearing having the same configuration, a tunnel having a plurality of grooves on the sliding surface and setting the gate position at the bottom position of the grooves A bearing in which a resin layer is formed by a gate is known (see Patent Document 2).

  These plain bearings are mainly developed as a substitute for rolling bearings, and polyethylene (hereinafter referred to as “base resin”) is used as a base resin for resin layers when used at a site where the operating temperature conditions are relatively low to achieve a low coefficient of friction. Often referred to as "PE" resin). PE resin can obtain a low coefficient of friction as compared with the case where polyacetal resin, polyphenylene sulfide resin, polytetrafluoroethylene (hereinafter referred to as "PTFE") resin or the like is adopted as a base resin.

Unexamined-Japanese-Patent No. 2003-239976 Patent No. 4515824

  In the above-described office equipment, in recent years, high functionalization, energy saving, and compactness are required, and therefore, the specification conditions (contact pressure (load) and sliding speed) of the sliding bearing are more severe. Also, when a slide bearing is used as a substitute for a rolling bearing, the substitutable range largely depends on the corresponding PV value (the surface pressure (P) multiplied by the sliding velocity (V)) of the slide bearing and 5 MPa M / min. About 20%, 15 MPa · m / min. About 85% of substitution is possible above.

  From such a background, as a slide bearing as a substitute for a rolling bearing in these devices, it is required to be able to handle a high PV value while maintaining a low coefficient of friction. As a general method for improving the friction and wear characteristics of resin sliding bearings, there is a method of blending solid lubricants such as PTFE resin powder, graphite powder, molybdenum disulfide and so on, but when base resin is other than PE resin It is difficult to make the dynamic friction coefficient μ about 0.1 or less.

  In the case of using a high molecular weight PE resin capable of injection molding as the base resin of the resin layer in the slide bearings of the structures of Patent Documents 1 and 2, although the low friction coefficient can be maintained, a high PV value (for example, 5 MPa · m In the case of exceeding / min., Sufficient abrasion resistance may not be obtained. On the other hand, when a non-injection moldable ultrahigh molecular weight polyethylene (hereinafter referred to as "UHMWPE") resin having an average molecular weight exceeding 1,000,000 is used as a base resin, insert injection molding can not be performed and productivity is inferior.

  The present invention has been made to address such problems, and it is an object of the present invention to provide a slide bearing capable of coping with high PV values while maintaining a low coefficient of friction and having excellent productivity. .

  The slide bearing according to the present invention is a slide bearing having a metal base and a resin layer integrally molded by injection molding using a resin material on the surface to be a sliding surface of the base, The material is a material mainly composed of an injection-moldable PE resin (A) and containing a non-injection-moldable UHMWPE resin (B), wherein the UHMWPE resin (B) is the PE resin (B). 5 to 30 mass% is included with respect to the total mass of A) and said UHMWPE resin (B). In particular, in the above-mentioned sliding bearing, the PV value obtained by multiplying the surface pressure (P) and the sliding speed (V) is 5 MPa · m / min. It is characterized in that it is a bearing used under conditions exceeding.

  It is characterized in that the weight average molecular weight of the above-mentioned UHMWPE resin (B) is 1,000,000 to 4,000,000. Further, the injection-moldable PE resin (A) is characterized in that the MFR measured at a load of 10 kg at 190 ° C. is 1 to 30 g / 10 min based on JIS K 7210.

  In the above-mentioned resin material, the above-mentioned UHMWPE resin (B) is characterized in that it is blended in the form of powder having an average particle diameter of 10 to 200 μm. In addition, this average particle diameter is a measured value by a laser diffraction method.

  The resin material is characterized in that it contains porous silica and silicone oil, and the porous silica is compounded in a state of being impregnated with the silicone oil in advance. In the above-mentioned resin material, the above-mentioned porous silica and the above-mentioned silicone oil are contained by 25-50 mass% to the whole resin material with a total mass of these.

  The thickness of the resin layer is 0.1 to 0.5 mm. The metal base is a sintered metal base.

  The above slide bearing is characterized in that it is used in a temperature atmosphere of 80 ° C. or less.

  The slide bearing of the present invention has a metal base and a resin layer integrally molded by injection molding using a resin material on the surface to be a sliding surface of the base, and the above resin material is injected A material comprising a moldable PE resin (A) as a main component and a non-injection moldable UHMWPE resin (B), wherein the UHMWPE resin (B) comprises a PE resin (A) and a UHMWPE resin ( Since it is contained in an amount of 5 to 30% by mass with respect to the total mass with B), the resin layer can be insert injection-molded, excellent in productivity, low friction at high PV value, and excellent in abrasion resistance. Furthermore, since the resin material contains porous silica and silicone oil and is compounded in a state in which the porous silica is impregnated with silicone oil beforehand, low friction can be maintained for a long period of time. As a result, the sliding bearing of the present invention can be suitably used as a substitute for a rolling bearing in many applications.

It is a perspective view and a sectional view showing an example of a slide bearing of the present invention. It is sectional drawing which shows the aspect of the structure of the resin layer formed in a bearing outer peripheral part. It is a figure which shows the relationship between PV value and a wear coefficient.

  The slide bearing according to the present invention has a metal base and a resin layer integrally molded (insert molding) by injection molding using a resin material on the surface of the base to be a sliding surface, The resin material which forms this resin layer is a material which has PE resin (A) which can be injection-molded as a main component, and contains a predetermined amount of non-injection moldable UHMWPE resin (B).

As PE resin (A) which becomes a main component of a resin material, PE resin which can be injection-molded should just be sufficient. The injection molding conditions may be, for example, those that can be injection molded at a molding temperature of 200 ° C. to 270 ° C. and an injection pressure of 100 to 160 MPa. In addition, high density, high molecular weight PE resin is excellent in various properties such as abrasion resistance, self-lubricity, impact resistance, chemical resistance, light weight lighter than specific gravity of water, dimensional stability due to low water absorption, etc. preferable. For example, a high density PE resin having a density (ASTM D 1505) of 942 kg / m ³ or more is preferable, and the upper limit of the density of the high density PE resin is less than 1000 kg / m ³ , strictly 980 kg / m ³ or less.

  As MFR (melt flow rate: JIS K 7210 (190 ° C., 10 kgf)) of the PE resin (A), 1 to 30 g / 10 min is preferable, 1 to 15 g / 10 min is more preferable, and 2 to 6 g / 10 min Is particularly preferred. The weight average molecular weight is less than 1,000,000, and preferably about 250,000 to 950,000. The structure may be linear or branched including a branch of a methyl group. In addition, PE resin of (A) component may be used individually by 1 type, and 2 or more types may be mixed and used.

Commercial products of PE resin (A) which can be used in the present invention include Lubber L 3000 (density: 969 kg / m ³ , MFR: 15 g / 10 min) manufactured by Mitsui Chemicals, Inc., L 4000 (density: 967 kg / m ³⁾ MFR: 6 g / 10 min), L5000 (density: 966 kg / m ³ , MFR: 2 g / 10 min), and the like.

  The UHMWPE resin (B) blended in the resin material is a non-injection moldable UHMWPE resin. UHMWPE resin is a resin in which the molecular weight of usually 20,000 to 300,000 of PE resin is increased to about 500,000 to 11,000,000, and has low friction characteristics. In addition, UHMWPE resin has a high molecular weight and therefore has good abrasion resistance. However, among UHMWPE resins, those having a molecular weight of 1,000,000 or more have extremely high viscosity at melting and hardly flow, so they can not be molded as a base resin by the usual injection molding method, and usually, they are heated After the material is formed by compression molding or ram extrusion, it is machined into a desired shape. Such non-injection moldable UHMWPE resin (B) has lower friction characteristics than the injection moldable PE resin (A) and is excellent in abrasion resistance. The non-injection moldable UHMWPE resin (B) preferably has a higher molecular weight than the PE resin (A).

  The weight average molecular weight of the non-injection moldable UHMWPE resin (B) is preferably 1,000,000 to 4,000,000. With less than one million UHMWPE resin powders, the effect of improving the wear resistance is poor. If it exceeds 4 million, thin formability is impaired.

  In the resin material, the non-injection moldable UHMWPE resin (B) is contained in an amount of 5 to 30% by mass with respect to the total mass (A + B) of the PE resin (A) and the non-injection moldable UHMWPE resin (B). If the amount is less than 5% by mass, the effect of improving the wear resistance is poor, and the pressure at 5 MPa · m / min. In the case of use at a PV value exceeding that, the wear resistance may be inferior. On the other hand, if it exceeds 30% by mass, injection moldability may be impaired. Preferably it is 8-30 mass%, More preferably, it is 14-30 mass%.

In the present invention, among the UHMWPE resins, particularly the non-injection moldable UHMWPE resin is used not as the main component of the resin layer but as a filler for improving wear resistance. The non-injection moldable UHMWPE resin (B) and the PE resin (A) are both resins of the same type having a main chain containing -CH ₂ -CH ₂ -units and are excellent in compatibility. The non-injection moldable UHMWPE resin (B) is dispersed in the PE resin (A) in a completely or partially dissolved state by melt-kneading at the time of injection molding.

  At the time of melt-kneading at the time of injection molding of the resin material, the non-injection moldable UHMWPE resin (B) is blended in the form of powder having an average particle diameter of 10 to 200 μm. Preferably, it is in the form of powder having an average particle size of 10 to 50 μm. By blending in the form of a fine powder, the thin-film formability of the resin layer is not inhibited, and the compatibility is also excellent, and abrasion resistance can be easily improved. Moreover, the powder of two or more types of UHMWPE resin (B) in which average particle diameters differ can also be mix | blended. Furthermore, the powder shape of the non-injection moldable UHMWPE resin (B) is preferably spherical since it is excellent in kneadability. The average particle size is a measured value by a laser diffraction method.

As a commercial product of non-injection moldable UHMWPE resin powder (B) which can be used in the present invention, trade name Miperon (spherical, weight average molecular weight: 2,000,000, density: 940 kg / m ³ , average particle diameter) manufactured by Mitsui Chemicals, Inc. 25-30 μm), the trade name of Hythex Million manufactured by Mitsui Chemicals, Inc. (weight average molecular weight: 1,150,000-4,000,000, density: 935-940 kg / m ³ , average particle diameter: 120-160 μm), and the like.

  The resin material forming the resin layer of the slide bearing is porous silica (C) which is a filler having communicating holes in addition to the injection moldable PE resin (A) and the non-injection moldable UHMWPE resin (B) It is preferable to blend the lubricant and the lubricant (D). Furthermore, a solid lubricant (E) can also be blended.

  As porous silica (C), the powder which has amorphous silicon dioxide as a main component can be used. For example, an aqueous solution of an alkali silicate containing an aggregate of fine particles having a primary particle diameter of 15 nm or more and an alkali metal salt or an alkaline earth metal salt is emulsified in an organic solvent and gelated with carbon dioxide And true spherical porous silica and the like. In the present invention, porous silica in which primary fine particles having a particle diameter of 3 to 8 nm are aggregated to form spherical silica particles is particularly preferable because it has communicating holes. The average particle diameter of the true spherical silica particles is preferably 0.5 to 100 μm, and in consideration of easy handling and slidability, 1 to 20 μm is particularly preferable. As such a true spherical porous silica, there may be mentioned trade name Sunsphere manufactured by AGC S.I.

A true spherical silica particle in which primary particles having a particle size of 3 to 8 nm are aggregated has a specific surface area of 200 to 900 m ² / g, preferably 300 to 800 m ² / g, a pore volume of 1 to 3.5 ml / g, It is preferable to have the characteristics that the pore diameter is 5 to 30 nm, preferably 20 to 30 nm, and the oil absorption is 150 to 400 ml / 100 g, preferably 300 to 400 ml / 100 g. In addition, it is preferable that the pore volume and the oil absorption amount be 90% or more before immersion, even if it is again dried after being immersed in water. In addition, said specific surface area and pore volume are the values measured according to JISK5101 by the nitrogen adsorption method, and oil absorption amount.

  In addition, it is preferable that the inner and outer surfaces of the true spherical silica particles be covered with silanol (Si-OH), since it is easy to hold lubricating oil and the like inside. In addition, porous silica can be subjected to surface treatment of organic and inorganic types suitable for the base material. The shape of the particles is not particularly limited, and non-spherical porous silica may be used as long as the average particle diameter, specific surface area, oil absorption and the like are within the range of the true spherical silica particles. In addition, spherical and spherical particles are more preferable from the viewpoint of the aggressivity to the counterpart material and the kneadability. Here, the term "spherical" refers to a sphere having a ratio of the minor axis to the major axis of 0.8 to 1.0, and the term "spherical" refers to a sphere closer to a true sphere than the above-mentioned spherical.

  As the lubricant (D), a substance having a lubricating effect such as a lubricating oil which is liquid at normal temperature, an ionic liquid, or a grease containing a thickener in the lubricating oil can be used.

  As the lubricating oil, any oil generally used for bearings can be used. For example, spindle oil, refrigeration oil, turbine oil, machine oil, mineral oil such as dynamo oil, polybutene, poly-α-olefin, alkyl naphthalene, Hydrocarbon synthetic oils such as alicyclic compounds, or ester oils of natural fats and oils, phosphoric acid esters, diester oils, polyglycol oils, silicone oils, polyphenyl ether oils, alkyl diphenyl ether oils, alkyl benzenes, fluorinated Non-hydrocarbon-based synthetic oils such as oil may be mentioned. As greases, these lubricating oils are used as a base oil, and soap thickeners such as metal soaps and complex metal soaps, or non-soap thickeners such as bentone, silica gel, urea compounds and urea / urethane compounds. And greases using In addition, solid wax may be blended.

  In the slide bearing of the present invention, since low friction is required, it is preferable to use silicone oil as the lubricant (D) among the above. The silicone oil is compatible with the silanol groups remaining on the porous silica surface described above. As the silicone oil, either a silicone oil having no functional group or a silicone oil having a functional group can be used.

  When the porous silica (C) and the lubricant (D) are mixed in the resin material, the kneading order is not particularly limited, but the porous silica and the lubricant are previously kneaded to impregnate the porous silica with the lubricant. After mixing, it is preferable to knead with other materials. It is also possible to impregnate a lubricant after the base resin and the porous silica are kneaded to form a compact. In addition, since porous silica easily absorbs moisture and absorbs water, it is preferable to dry it before kneading. The drying method is not particularly limited, and drying in an electric furnace, vacuum drying, or the like can be employed. Since the lubricating oil can be sufficiently retained in the porous silica and the kneadability is also excellent, it is preferable to be blended with other materials in the state of oil-impregnated porous silica in which the porous silica is impregnated with silicone oil or the like in advance.

  In the resin material, the porous silica (C) and the lubricant (D) such as silicone oil are preferably contained in a total mass (C + D) of 25 to 50% by mass based on the whole resin material. More preferably, it is 25 to 45% by mass, still more preferably 30 to 40% by mass, and most preferably 35 to 40% by mass. In addition, it is preferable to set it as (C) :( D) = about 1: 3 in mass conversion as breakdown. By blending 25 to 50% by mass of the oil-impregnated porous silica with respect to the entire resin material, the lubricating oil can be provided with excellent supplyability, and excellent frictional wear characteristics can be maintained.

  Moreover, it is also possible to impregnate the above-mentioned lubricating oil in the bearing peripheral part which consists of a sintered metal base material, and make it leak out to a sliding face via a resin layer which has the above-mentioned communicating hole structure, and to make it lubricate.

  As the solid lubricant (E), PTFE resin, graphite, molybdenum disulfide, boron nitride, tungsten disulfide and the like can be used.

  The PTFE resin (powder) may be any of molding powder by suspension polymerization, fine powder by emulsion polymerization, and heat-fired PTFE resin powder, but heat-fired PTFE resin powder may be employed. preferable. This is because molding powders and fine powders which are not heat-fired have low friction characteristics but are inferior in uniform dispersibility and abrasion resistance. The heat-fired PTFE resin powder may be a powder obtained by heat-baking (material forming, heat treatment) molding powder or fine powder, or a powder obtained by further irradiating this powder with γ-rays or electron beams. The particle diameter of the PTFE resin powder is not particularly limited, but in order to obtain stable low friction characteristics, the average particle diameter is preferably 5 to 30 μm.

  In addition, an appropriate filler can be added to the resin material forming the resin layer of the slide bearing in order to improve the friction and wear characteristics and to reduce the linear expansion coefficient. For example, fibers such as glass fiber, carbon fiber, pitch carbon fiber, PAN carbon fiber, aramid fiber, alumina fiber, polyester fiber, polyester fiber, boron fiber, silicon carbide fiber, boron nitride fiber, silicon nitride fiber, metal fiber, and the like Such as calcium carbonate and talc, silica, clay, mica and other minerals, inorganic whiskers such as aluminum borate whisker and potassium titanate whisker, various heat resistant resins such as polyimide resin and polybenzimidazole Can be mentioned. In addition, when there exists a possibility of attacking a soft mating material, a fibrous filler is not mix | blended. Furthermore, known additives may be used in combination in amounts that do not inhibit the effects of the present invention. For example, additives such as antistatic agents (carbon nanofibers, carbon black, graphite, etc.), mold release agents, flame retardants, weather resistance improvers, antioxidants, pigments, etc. may be added as appropriate, and these are added The method is also not particularly limited.

  In the slide bearing of the present invention, the most preferable composition as the resin material for forming the resin layer is injection-moldable PE resin (A), non-injection moldable UHMWPE resin (B), porous silica (C), silicone oil Etc. is a composition comprising substantially four components of a lubricant (D). In this case, when the porous silica (C) and the lubricant (D) such as silicone oil are 25 to 50% by mass with respect to the whole resin material in total mass (C + D), PE resin (A) and UHMWPE The total mass (A + B) with the resin (B) is 50 to 75% by mass with respect to the entire resin material.

  In the resin material forming the resin layer of the slide bearing, the means for mixing and kneading the various raw materials is not particularly limited, and they are mixed by a Henschel mixer, ball mixer, ribbon blender, Loedige mixer, etc. The mixture is melt-kneaded with a melt extruder such as a shaft extruder to obtain molding pellets. In addition, side materials may be used to feed part of the filler material when melt kneading is performed using a twin-screw extruder or the like. Using this molding pellet, the resin layer is injection molded on the metal base by insert molding. By employing injection molding, it is excellent in precision moldability and productivity. Further, a treatment such as annealing may be employed to improve physical properties.

  Even when a porous silica impregnated with silicone oil is compounded only by using the PE resin (A) as the resin base material of the resin material, the PV value is 3 MPa · m / min. It could be used under conditions up to a certain degree, and there was a risk that the abrasion resistance would be significantly deteriorated at a PV value exceeding this. On the other hand, the abrasion resistance at a high PV value is significantly improved by substituting and blending a part of the PE resin (A) with the non-injection moldable UHMWPE resin (B) in a predetermined compounding range. It was possible. In particular, Libumer L5000 manufactured by Mitsui Chemicals, Inc. is used as PE resin (A), and Miperon XM 220 manufactured by Mitsui Chemicals, Inc. is adopted as non-injection moldable UHMWPE resin (B). By blending porous silica impregnated with silicone oil, 15 MPa · m / min. It was possible to obtain a slide bearing that can exhibit excellent wear resistance even with the above high PV value (see Examples described later). As a result, the sliding bearing of the present invention can be suitably used as a substitute for a rolling bearing in many applications.

  The slide bearing of the present invention will be described with reference to FIG. Fig.1 (a) shows the perspective view of a slide bearing, FIG.1 (b) shows AA sectional drawing, respectively. In the slide bearing 1, the bearing outer peripheral portion 2 is formed of a sintered metal base material, and on the inner peripheral side to be a sliding portion of the bearing outer peripheral portion 2, a resin layer using the above-described resin material (pellet for molding) 3 is insert-molded through a tunnel gate. The resin layer 3 has a plurality of grooves 4 on the bearing sliding surface, and a gate mark 5 is formed at the bottom of the grooves 4. In FIG. 1A, the plurality of grooves 4 are formed as axial grooves 4A and 4B in the radial sliding surface of the cylindrical bearing, and the gate mark 5 is formed at the bottom position of the axial groove 4A. The gate mark 5 is not formed in 4B. Further, the plurality of grooves 4 can be provided on the radial sliding surface, the thrust sliding surface, or both the radial sliding surface and the thrust sliding surface of the cylindrical bearing.

  Insert molding through a tunnel gate can be performed using a known mold structure. Since the tunnel gate mark is formed at the bottom position of the groove, gate processing in the forming process is not necessary, and mass production is possible while having high accuracy.

  The plurality of axial grooves 4 are composed of a groove 4A having a tunnel gate mark and a groove 4B having no tunnel gate mark. Further, they are arranged such that the distance on the bearing sliding surface from the both sides of the groove 4A to the groove 4B is equal. Preferably, the same number of grooves A and grooves B are formed at equal intervals. By this arrangement, a weld portion at the time of injection molding is formed in the groove B. Furthermore, wear powder can be captured in the groove 4 to suppress the occurrence of abnormal wear.

  The bearing outer peripheral part 2 is a cylindrical member which comprises the outer peripheral part of a slide bearing, and is a member which has a sliding part. The sliding portion means an inner diameter side sliding portion for supporting a load in the radial direction, and when supporting a load in the thrust direction, not only the above-mentioned internal sliding portion but also the end surface slide Also includes moving parts.

  The material of the sintered metal base material constituting the bearing outer peripheral portion 2 includes Fe-based sintered metal, Cu-based sintered metal, Fe-Cu-based sintered metal, and may contain C, Zn, or Sn as components. Good. In addition, a small amount of a binder may be added to improve moldability and releasability. Furthermore, a material in which aluminum, Cu, Mg, and Si are mixed, or a metal-synthetic resin in which iron powder is bonded with an epoxy-based synthetic resin may be used. Furthermore, in order to improve adhesion to the resin layer, it is possible to apply surface treatment or to interpose an adhesive, as long as the molding is not inhibited.

  Fe-based sintered metals are preferable when obtaining a slide bearing having excellent mechanical strength and durability with high dimensional accuracy and rotational accuracy. Here, "Fe-based" means that the content of Fe is 90% or more in mass ratio. As long as this condition is satisfied, other components such as Cu, Sn, Zn and C may be contained. Also, "Fe" includes stainless steel. For example, the Fe-based sintered metal is formed into a predetermined shape by degreasing a raw material metal powder containing a content of Fe described above (a small amount of a binder may be added to improve moldability and releasability), and degreased, It can form by giving post-processes, such as sizing, to the sintered compact obtained by baking as needed. Inside the sintered metal, there are a large number of internal pores due to a porous structure, and on the surface there are a large number of surface openings formed by the internal pores opening to the outside. The internal pores can be impregnated with the above-mentioned lubricating oil, for example by vacuum impregnation.

  The resin layer 3 is insert-molded on the sliding portion of the bearing outer peripheral portion 2 made of a sintered metal base material to form a bearing surface that slides on the shaft member. At the time of molding, the molten resin forming the resin layer enters the internal pores of the surface layer portion from the surface opening and solidifies, and thus the resin layer firmly adheres to the base surface by a kind of anchor solidification. Therefore, peeling and falling off of the resin layer due to sliding with the shaft member hardly occur, and high durability can be obtained.

  The surface open area ratio of the surface on which the resin layer made of the sintered metal base material is formed is preferably 20 to 50%. If the surface porosity is less than 20%, the anchor effect on the resin layer may not be sufficiently obtained, and if the surface porosity exceeds 50%, dimensional accuracy and mechanical strength may not be maintained. The “surface open area ratio” is the ratio (area ratio) of the total area of the surface open per unit area of the surface.

  The bearing outer peripheral portion 2 may be formed of a molten metal base material. The molten metal material is preferably iron, aluminum, an aluminum alloy, copper or a copper alloy. Examples of iron include carbon steel for general structure (SS400 etc.), mild steel (SPCC, SPCE etc.), stainless steel (SUS304, SUS316 etc.), etc. These irons may be plated with zinc, nickel, copper etc. . Examples of aluminum include A1100 and A1050, examples of the aluminum alloy include A2017 and A5052 (including an alumite treated product), examples of copper include C1100, and examples of copper alloys include C2700 and C2801.

  When the bearing outer peripheral portion 2 is made of a molten metal base, the bonding surface is roughened into a concavo-convex shape by shot blasting, tumbler, mechanical processing or the like in order to enhance adhesion with the resin layer at the time of insert molding Ra of 4 μm or more) is preferable. In addition, chemical surface treatment such as acid solution treatment (mixture with sulfuric acid, nitric acid, hydrochloric acid, etc. or other solution), alkaline solution treatment (sodium hydroxide, potassium hydroxide etc, or mixture with other solution), etc. is applied. It is preferable to form a fine uneven shape on the bonding surface. The fine uneven shape formed by the chemical surface treatment has a complex three-dimensional structure such as a porous material, so that the anchor effect is easily exhibited, and strong adhesion can be achieved.

  In the resin layer, (linear expansion coefficient of resin material (unit: 1 / ° C.) × (thickness of resin layer (unit: μm)) is preferably 0.15 or less, preferably 0.13 or less, 0.10 More preferably, if the above value is greater than 0.15, the thickness or expansion of the resin layer will also be large, since the outer diameter side of the resin layer is constrained by the metal base material. It can not expand more than the expansion, expand to the inner diameter side and reduce the inner diameter size, resulting in a decrease in the gap with the shaft, and depending on the initial gap setting, there is a possibility that the temperature may rise due to temperature increase. In addition, excessive gap fluctuation is not preferable because it causes torque fluctuation, and it is preferable from the viewpoint of rotational accuracy that the gap be smaller.Furthermore, dimensional change due to water absorption is also large, and excessive gap fluctuation occurs. There is.

  Moreover, the thickness of the resin layer which can be molded is about 50 μm, and if it is thinner than this, the formation becomes difficult. Therefore, the resin expansion coefficient × thickness must be 0.003 or more, preferably 0.01 or more, and more preferably 0.015 or more.

  The thickness of the resin layer is preferably set to 0.1 to 0.5 mm (100 to 500 μm). In the present invention, "the thickness of the resin layer" is the thickness (thickness in the radial direction) of the surface portion which does not enter the metal base. If the thickness of the resin layer is less than 0.1 mm, the durability during long-term use may be poor. On the other hand, if the thickness of the resin layer exceeds 0.5 mm, sink marks may occur and the dimensional accuracy may decrease. In addition, the heat due to friction is unlikely to escape from the friction surface to the metal substrate, and the temperature of the friction surface is increased. Furthermore, as the amount of deformation due to load increases, the true contact area on the friction surface also increases, which may increase the frictional force and the frictional heat generation.

  As the shape of the slide bearing of the present invention, an optimum bearing shape can be selected according to the shape of the sliding portion, such as a radial type, a flat type, a flanged bush and the like. Moreover, although the aspect which has a some groove | channel in a bearing sliding surface was demonstrated in FIG. 1, it is not limited to this, The aspect which does not form this groove may be sufficient.

  Moreover, the location which insert-molds to the bearing outer peripheral part of a resin layer will not be specifically limited if it is a sliding part of a bearing outer peripheral part. For example, the case as shown to Fig.2 (a)-(e) is mentioned. 2 (a) and 2 (e), the resin layer 3 is formed on the radially inner radial sliding surface of the bearing outer peripheral portion 2 in order to support the load in the radial direction. 2 (b) (c) (d), in order to support the load in the radial direction and the thrust direction, the resin layer 3 is formed on the radial sliding surface on the inner diameter side of the bearing outer peripheral portion 2 and the thrust sliding surface It is. Although not shown, it is also possible to apply a resin layer to the outer diameter portion of the bearing as necessary. In addition, as shown to FIG.2 (c) (e), you may employ | adopt the shape of the resin layer which has a hook part which a bearing outer peripheral part and a resin layer do not separate.

  The slide bearing of the present invention is highly accurate and is excellent in sliding characteristics (low friction, low wear), and does not attack soft counterparts such as an aluminum shaft, and can also suppress the generation of abnormal noise. For this reason, it can be used as a bearing for supporting the rotating shaft of rotating parts in developing units, photosensitive units, transfer units and the like of office machines such as copying machines and printers. In addition, since it has PE resin as a main component, it can utilize suitably mainly in the temperature atmosphere below 80 degreeC.

  In addition, 15 MPa · m / min. Since the use with the above high PV value is also possible, it can replace and use to this rolling bearing also about the part used by the load and speed which were conventionally corresponded by the rolling bearing.

  The slide bearings of Examples and Comparative Examples were produced by the following materials and molding methods, and predetermined friction and wear tests were conducted on those which were able to mold a resin layer.

1. Resin material base resin;
(A) Injection moldable PE resin [trade name Lubber L 5000 manufactured by Mitsui Chemicals, Inc.] (density (ASTM D 1505): 966 kg / m ³ , MFR (JIS K 7210 (190 ° C., 10 kgf)): 2 g / 10 min )
filler;
(B) Non-injection moldable UHMWPE resin [Miperon XM 220 manufactured by Mitsui Chemicals, Inc.] (weight average molecular weight: 2,000,000, average particle size (laser diffraction method): 30 μm, bulk specific gravity (ASTM D 1895): 400 kg / M ³ , Shore hardness (ASTM D3418): 65 D, spherical particles)
(C) Porous silica [trade name Sunsphere H53 manufactured by AGC S ITEC Co., Ltd.]
(D) Silicone oil [trade name KF-96H manufactured by Shin-Etsu Chemical Co., Ltd.]
A mixture (oil-impregnated porous silica) having a mixing ratio of porous silica to silicone oil of 1: 3 (mass conversion) is obtained, and this mixture is 39% by mass with respect to the entire resin material, and an injection moldable PE resin A mixture of X% by mass and Y% by mass of non-injection moldable UHMWPE resin was melt-kneaded by a twin-screw extruder to prepare molding pellets. Here, (X mass% + Y mass%) = 61 mass%, and the details are according to Table 2.

2. Outer ring made of sintered metal base (sintered outer ring)
Size: φ 8.5 mm (inner diameter), φ 16 mm (outer diameter), 5 mm (height)
Component: Copper (0.5 to 2.5% by mass), others (3% or less by mass), iron (remaining amount)
Production process: Material powder blending, forming, sintering, sizing, rust prevention and drying

3. Insert Molding Conditions A sintered outer ring of the above shape was inserted into a mold, and insert molding was performed under the following conditions through a tunnel gate using the molding pellet obtained above. The thickness of the resin layer is 0.25 mm.
Finished product size: φ 8 mm (inner diameter), φ 16 mm (outer diameter), 5 mm (height)
Mold temperature: 120 ° C
Molding temperature: 250 ° C
Injection pressure: 100 to 140MPa

摩耗係数
ｋ＝δ／（Ｆ×Ｄ）
ｋ：摩耗係数 ｍｍ／（Ｎ×ｍ） 定義：単位仕事量当たりの真円度増加量
Ｆ：ラジアル荷重 Ｎ
Ｄ：総滑り距離 ｍ
δ：摩耗量（真円度の増加量） ｍｍ δ＝δ１−δ０
δ０：試験前の供試軸受の内径２断面真円度（半径法）の平均値
δ１：試験後の供試軸受の内径２断面真円度（半径法）の平均値 4. Friction and Wear Test The friction and wear test was conducted under the conditions of Table 1 below. The gap between the mating material shaft and the slide bearing was 20 μm (measured at 20 ° C.). Further, the wear coefficient was calculated by the following equation. The results of the friction and wear test are shown in Table 2.

Wear factor k = δ / (F × D)
k: Wear factor mm / (N × m) Definition: Roundness increase per unit work amount F: Radial load N
D: Total slip distance m
δ: Wear amount (increase in roundness) mm δ = δ1-δ0
δ0: Average value of inner diameter 2 cross section roundness (radius method) of test bearing before test δ1: Average value of inner diameter 2 cross section circularity (radius method) of test bearing after test

  As shown in Table 2, each example in which a non-injection moldable UHMWPE resin is contained in a predetermined range in the PE resin is injection moldable, and the coefficient of friction is low at any of the PV values of 5 and 15 MPa · m / min. It is also understood that the wear resistance is excellent.

  Further, as Comparative Example 3, the same as Example 1 except that the non-injection moldable UHMWPE resin (B) is not contained and the injection moldable PE resin (A) is 61 mass% with respect to the entire resin material. The sliding bearings were manufactured under the conditions. The above-mentioned friction and wear test was conducted a plurality of times for this Comparative Example 3 and Example 2, and the relationship between the PV value and the above-mentioned wear coefficient was examined. The results are shown in Table 3 and FIG. In addition, FIG. 3 is the figure which plotted the PV value on the horizontal axis, and set the abrasion coefficient on the vertical axis about the data of Table 3. As shown in FIG.

  As shown in Table 3 and FIG. 3, in Comparative Example 3 which does not contain any non-injection moldable UHMWPE resin, it is understood that the wear resistance is significantly deteriorated when the PV value exceeds 3 MPa · m / min. . Also, at high PV values, the variation in the wear coefficient for each measurement is also large. On the other hand, in Example 2 in which the non-injection moldable UHMWPE resin is partially contained, the abrasion resistance is excellent and the variation is small at any of the PV values of 5, 10 and 15 MPa · m / min. I understand.

  The slide bearing of the present invention can cope with a high PV value while maintaining a low coefficient of friction, and is excellent in productivity, so that it can be suitably used particularly as a substitute for a rolling bearing in office equipment.

1 Slide bearing 2 Bearing outer peripheral portion 3 Resin layer 4 Groove 5 Gate mark

Claims (4)

A slide bearing comprising: a metal base; and a resin layer which is an injection-molded layer of a resin material integrally provided on a surface which is a sliding surface of the base,
In the slide bearing, a bearing outer peripheral portion is made of the metal base material, the resin layer is provided on an inner peripheral side which is a sliding portion of the bearing outer peripheral portion, and the sliding portion rotates the rotating parts of office equipment The axis is supported, and the PV value obtained by multiplying the surface pressure (P) and the sliding speed (V) is 5 MPa · m / min. Bearings used under conditions above
The resin material is impregnated with a silicone oil and a non-injection moldable ultrahigh molecular weight polyethylene resin (B) mainly composed of an injection moldable polyethylene resin (A) and having a weight average molecular weight of 1,000,000 to 4,000,000 And porous silica, and
In the resin material, the powdered ultra-high molecular weight polyethylene resin (B) is contained in a proportion of 5 to 30% by mass with respect to the total mass of the polyethylene resin (A) and the ultra-high molecular weight polyethylene resin (B) In the resin layer, the ultrahigh molecular weight polyethylene resin (B) is dispersed in the polyethylene resin (A) ,
A sliding bearing characterized in that, in the resin material, 35 to 50% by mass of porous silica impregnated with the silicone oil is contained with respect to the entire resin material .   The slide bearing according to claim 1, wherein the injection moldable polyethylene resin (A) has a MFR of 1 to 30 g / 10 min when measured at 190 ° C under a load of 10 kg based on JIS K 7210. . The slide bearing according to claim 1 or 2, wherein the metal base is a sintered metal base. The slide bearing according to any one of claims 1 to 3 , wherein the slide bearing is a bearing used in a temperature atmosphere of 80 ° C or less.

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