JP2019065925A - Slide bearing - Google Patents

Abstract

To provide a low-friction and low-torque slide bearing having a bearing surface in contact with an outer peripheral surface of a rotary shaft, being capable of reducing frictional wear between the bearing surface and the rotary shaft and reducing adverse influences caused by a generated abrasion powder and further also being improved in a supply performance and a holding property of grease or the like.SOLUTION: A slide bearing 1 comprises a bearing surface 3 in contact with an outer peripheral surface of a rotary shaft 4. The bearing surface 3 is a cylindrical surface or partially cylindrical surface along the outer peripheral surface of the rotary shaft 4 and includes a groove 5 in an axial direction of the rotary shaft 4 in a portion of the bearing surface 3 receiving a load in slide contact with the rotary shaft 4. Within the groove 5, an implanted part 14 is included by implanting fibers, and the implanted part 14 is impregnated with a lubricant or the like.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a slide bearing. In particular, the slip applied to applications that support the rotation shaft of a fixing roller of a fixing unit in an image forming apparatus such as a copying machine, a multifunction machine, a printer (laser beam printer, ink jet printer, etc.) and a facsimile It relates to a bearing.

  A fixing device of an image forming apparatus such as a copying machine or a printer fixes the unfixed toner transferred from the photosensitive drum to a sheet by heat and pressure. The fixing device simultaneously applies heat and pressure by causing a sheet to enter between a fixing roller containing a heat source such as a halogen heater and a ceramic heater in a cylindrical body and a pressure roller installed opposite to the fixing roller. A mechanism for fixing the toner is common. The outer peripheral surface of one of the fixing roller and the pressure roller is an elastic body such as synthetic rubber, and the other is a rigid body. Also, instead of the pressure roller, a mechanism for pressing an endless belt made of stainless steel, polyimide resin or the like to the fixing roller side via an elastic body is also employed.

  The fixing roller and the pressure roller are rotatably supported by bearings at both ends of the rotation shaft. As the bearing, a ball bearing (rolling bearing), a sintered oil-impregnated bearing, a resin slide bearing or the like is used. As a resin slide bearing used for such an application, a U-shape having an opening or a cylindrical shape is often used, and in use, grease is often applied to a bearing surface.

  Since copying machines and printers are increasing in printing speed and reducing power consumption year after year, bearings are required to cope with high load and high speed conditions, to reduce torque, and to improve friction and wear resistance. Further, depending on the structure of the fixing device, conductivity is also required. Ball bearings have higher load resistance and lower torque than sintered oil-impregnated bearings and resin slide bearings, but are expensive. Although sintered oil-impregnated bearings are low in cost, they have the disadvantage that they have less design freedom than injection-molded resin slide bearings. Therefore, the application of a slide bearing is desired even in models with high printing speed.

  As a method of reducing the contact area between the bearing surface and the rotary shaft, the torque is reduced by setting the axial length of the portion where the bearing surface contacts the rotary shaft to be shorter than the total axial length of the slide bearing. A method has been proposed (see Patent Document 1).

  In addition, for the purpose of improving lubrication characteristics including reduction of rotational torque of the bearing, a rolling bearing in which a flocked portion formed by flocking fibers is formed on the surface that contacts the lubricant other than the contact surface with the rolling element. It is proposed (refer patent document 2).

Japanese Patent Application Laid-Open No. 5-26228 International Publication No. 2015/141822

  However, with the recent increase in printing speed of image forming apparatuses in recent years, the required characteristics for bearings have become more severe. For example, it is required to minimize the bearing diameter in order to reduce the cost. If the bearing diameter is reduced, the contact between the bearing and the shaft can not be received over the entire inner diameter of the bearing due to high load. As a result, at the time of initial use of the bearing, there is a problem that a large amount of wear powder is generated in the bearing because the bearing edge receives a load. Further, the generated wear powder is retained by the grease, and there is a problem that the retained wear powder adversely affects the frictional wear in a vicious cycle in which the bearing is further worn.

  In general, in the case of forming a grease groove or in the case of forming a flocked portion for the purpose of improving the retention of grease, the opposite effect may be obtained depending on the shape, position, and use conditions. Effect may not be obtained.

  The present invention has been made to address these problems, and in a slide bearing provided with a bearing surface in contact with the outer peripheral surface of a rotating shaft, the friction between the bearing surface and the rotating shaft can be reduced, and the generated wear An object of the present invention is to provide a low-wear and low-torque slide bearing which can reduce the adverse effect of powder and is excellent in supplyability and retention of grease and the like.

  The sliding bearing according to the present invention is a sliding bearing comprising a bearing surface in contact with the outer peripheral surface of a rotating shaft, wherein the bearing surface is a cylindrical surface or a partial cylindrical surface along the outer peripheral surface of the rotating shaft. A flocked portion having one or a plurality of grooves along the axial direction of the rotating shaft in a portion receiving the load in sliding contact with the rotating shaft in the bearing surface, and fibers being flocked in the grooves It is characterized by having.

  It is characterized in that the above-mentioned flocking part is impregnated with a lubricant. In addition, the tip of the fiber is in contact with the rotation shaft.

  In the bearing surface, an offset load in a non-perpendicular direction is applied to the axis of the rotating shaft, and of axial both end portions of the bearing surface, the axial end portion on the side where the load received by the offset load is large, It is characterized in that it has an inclined groove formed so as to expand the diameter of the bearing surface toward the axial outer side of the end.

  It is characterized in that the fibers which are flocked in the flocked part are synthetic resin fibers. Further, the slide bearing of the present invention is characterized in that it is a bearing for supporting a rotation shaft of a fixing roller or a pressure roller in an image forming apparatus.

  The slide bearing of the present invention can reduce the contact area at the load portion and reduce the friction between the bearing surface and the rotating shaft, as compared to the case where there is no predetermined groove. Further, wear powder can be held at the flocked portion in the groove, and the adverse effect of wear due to the generated wear powder can be reduced. Furthermore, since the flocking part in the groove is impregnated and held with a lubricant such as grease or lubricating oil, it is excellent in its holding property and supply property, and the lubricant can be stably supplied to the load part for a long period of time. As a result, the sliding bearing of the present invention can maintain a good sliding condition in the load portion, resulting in a low wear and low torque sliding bearing.

It is the perspective view and sectional drawing which show an example of the sliding bearing of this invention. It is the perspective view and sectional drawing which show the other example of the slide bearing of this invention. It is a perspective view which shows the other example of the sliding bearing of this invention. FIG. 5 is a schematic view (side view) showing the configuration of a fixing unit of the image forming apparatus. FIG. 2 is a schematic view (cross section) showing the configuration of a fixing unit of the image forming apparatus.

  The configuration of the fixing portion of the image forming apparatus using the slide bearing of the present invention will be described based on FIGS. 4 and 5. FIG. FIG. 4 is a schematic view of the fixing unit viewed from the side. The image forming apparatus forms an image captured by the optical unit with toner on the transfer belt in the developing unit and the photosensitive unit. As shown in FIG. 4, in the fixing unit, the toner 9 is transferred to the sheet 10 and is printed on the sheet 10. At this time, the sheet 10 passes between the fixing roller 6 and the pressure roller 7 (nip portion), and is heated and pressurized at about 200 ° C. to burn the toner 9. The peeling member 8 is provided at a position in contact with or in proximity to the fixing roller 6 so that the sheet 10 having passed through the nip portion can be peeled off from the fixing roller 6. In the fixing roller 6, heat is transmitted through the belt, or the heater 12 is built in and the temperature becomes high. The respective rotation shafts of the fixing roller 6 and the pressure roller 7 are rotatably supported by bearings. Here, the pressure roller 7 is pressed against the fixing roller 6 by a spring 11 or the like through the slide bearing 1 of the present invention.

  The offset load acting on the slide bearing 1 will be described with reference to FIG. FIG. 5 is a schematic cross-sectional view of the fixing unit. The slide bearing 1 supporting the rotation shaft 4 of the pressure roller 7 is always pressed in a direction perpendicular to the axis of the rotation shaft 4 with a load in one direction, but in fact the rotation shaft 4 is bent. A load is received at the edge 3 a of the bearing surface 3. Thus, the magnitude of the load received at the axial position of the bearing surface 3 is different. Due to the deflection and thermal expansion of the rotary shaft 4, both axial load and radial load are applied to the bearing surface 3, and a non-perpendicular (oblique) load is applied to the axis of the rotary shaft. When the printing speed is increased, it is necessary to burn the toner in a short time, so both the temperature of the fixing roller 6 and the pressing force of the pressure roller 7 become high, and the use condition of the bearing becomes severe.

  An example of the slide bearing of the present invention will be described based on FIG. FIG. 1 (a) is a perspective view of the slide bearing, and FIG. 1 (b) is an axial sectional view of the slide bearing. As shown in FIG. 1 (a) and FIG. 1 (b), the slide bearing 1 of this embodiment is composed of a U-shaped bearing main body 2 having a predetermined axial thickness. And the like, and has a bearing surface 3 in contact with and supporting the outer peripheral surface of the rotary shaft 4. The bearing surface 3 is formed on the U-shaped bottom side of the bearing body 2 and the U-shaped upper side is open. The bearing surface 3 is a partial cylindrical surface (arc surface) along the outer peripheral surface of the rotating shaft 4. The surface of the bearing surface 3 has a single concave groove 5 along the axial direction of the rotation shaft (X-ray in FIG. 1 (b)). The diameter of the rotary shaft 4 supported by the slide bearing 1 is the same as or slightly smaller than the distance between the inner wall surfaces 2a and 2b of the bearing body 2.

  The groove 5 is provided in a portion (load portion) in sliding contact with the rotary shaft 4 in the bearing surface 3 to receive a load. In the embodiment shown in FIG. 1, the U-shaped bearing main body 2 is provided at the lowest portion between the inner wall surfaces 2a and 2b, and this portion is the portion that receives the most load. The groove 5 is a rectangular groove having a rectangular shape in the depth direction, and has a flocked portion 14 in which fibers are flocked in the groove 5.

  By forming the groove 5 in the load portion of the bearing surface 3, the contact area in the load portion can be reduced, and the friction can be reduced. Further, the generated wear powder is caught between the fibers by the flocked portion 14 of the groove 5 and held there, so that the wear powder can be prevented from being supplied again to the sliding contact surface, and the wear by the generated wear powder Can reduce the adverse effects of Furthermore, since the flocking portion 14 in the groove 5 formed in the load portion is impregnated with a lubricant such as grease or lubricating oil, it is excellent in the retentivity and supply property, and the lubricant in the load portion stably over a long period of time Can be supplied.

  Another example of the slide bearing of the present invention will be described based on FIG. FIG. 2 (a) is a perspective view of the slide bearing, and FIG. 2 (b) is an axial sectional view of the slide bearing. As shown in FIGS. 2 (a) and 2 (b), the slide bearing 1 of this embodiment has inclined grooves 13 in the edge portion 3a of the bearing surface 3 which is in sliding contact with the rotating shaft 4 at the beginning of operation. The edge 3 a is an axial end on the side of the bearing surface 3 on which the load received by the offset load is large. The inclined groove 13 is formed in the edge portion 3 a so as to expand the diameter of the bearing surface 3 which is a circular arc surface toward the axial direction outer side (outside of the bearing). By providing such an inclined groove 13, it becomes easy to receive the above-mentioned uneven load.

  Also in this embodiment, the groove 5 and the flocked portion 14 are formed in the same manner as shown in FIG. When the rotating shaft 4 rotates, initial wear contact is generated by the initial sliding contact at the edge portion 3a of the bearing surface 3, and this wear can be suppressed by the inclined groove 13. In addition, even when the initial wear powder is generated, the wear powder is held between the fibers of the flocked portion 14 of the groove 5 and does not enter the sliding contact surface.

  In each embodiment, the circumferential width of the groove is preferably 2 to 10%, particularly preferably 2 to 6%, of the outer peripheral length of the rotation shaft. It is preferable that the axial length of the groove penetrates to both bearing end surfaces in the axial direction. The depth of the groove is preferably such a depth that the fibers of the flocked part do not protrude or slightly protrude. By improving the feedability of the lubricant held by the flocking part while minimizing the increase in resistance due to the contact by setting the tip end of the fiber of the flocking part to slightly contact (light contact) with the rotating shaft Can.

  Moreover, although the said groove | channel is along the axial direction of a rotating shaft, this may not be limited to what was completely along (parallel or coincidence), and may be slightly inclined. The inclination allowable angle is, for example, about 0 ° to 20 °. This inclination is the same for both the load direction and the horizontal direction (direction perpendicular to the load direction). In addition, although one groove is formed in the vicinity of the arc center of the bearing surface (arc surface) in FIGS. 1 and 2, the invention is not limited thereto, and the number of grooves may be plural.

  Although the form in which a bearing surface is a partial cylindrical surface along the outer peripheral surface of a rotating shaft was demonstrated in FIG. 1 and FIG. 2, a cylindrical body is used for a bearing main body and a bearing surface follows the outer peripheral surface of a rotating shaft It may be a cylindrical surface.

  Another example of the slide bearing of the present invention will be described based on FIG. FIG. 3 is a perspective view of this sliding bearing. The sliding bearing 1 'of this embodiment comprises a bearing body 2 of a substantially cylindrical body having a predetermined axial thickness, and the bearing body 2 contacts the outer peripheral surface of the rotating shaft 4 such as a pressure roller to support it. Bearing surface 3. The bearing surface 3 is formed on the inner peripheral surface of the bearing main body 2, and its shape is a cylindrical surface along the outer peripheral surface of the rotating shaft 4. The surface of the bearing surface 3 has a concave groove 5 along the axial direction of the rotating shaft 4. A flocked portion 14 in which fibers are flocked is provided in the groove 5. The diameter of the rotary shaft 4 supported by the slide bearing 1 'is the same as or slightly smaller than the inner diameter of the cylindrical portion of the bearing body 2.

  In the slide bearing 1 ′ of FIG. 4, a load is received on the bearing surface on the lower side of the cylinder. The groove 5 including the flocked portion 14 is formed in a portion receiving the load of the inner peripheral surface (bearing surface 3) of the bearing main body 2 in consideration of the fixing direction of the bearing main body 2. Thereby, the same effect as in the case of the embodiment of FIG. 1 or the like can be obtained.

  In the configuration shown in each of the above figures, the flocked portion 14 can be formed by flocking a short fiber on the bottom of the groove 5. Spraying or electrostatic flocking can be employed as the flocking coating method. It is preferable to adopt electrostatic flocking because a large amount of fibers can be densely and vertically flocked in a groove in a short time. A publicly known method can be adopted as the electrostatic flocking method. For example, as an electrostatic flocking method, (1) a step of applying an adhesive to the area to which electrostatic flocking is to be applied on the bottom surface of the groove or the like; (2) the shorted charged fibers are sprayed into the groove; (3) drying the surface on which the short fibers are temporarily attached to sufficiently cure the adhesive, and fixing the short fibers in the groove, and the like. .

  Examples of the adhesive that can be used for electrostatic flocking include adhesives having as a main component urethane resin, epoxy resin, acrylic resin, vinyl acetate resin, polyimide resin, silicone resin and the like. For example, urethane resin solvent based adhesives, epoxy resin solvent based adhesives, vinyl acetate resin solvent based adhesives, acrylic resin based emulsion adhesives, acrylic acid ester-vinyl acetate copolymer based emulsion adhesives, vinyl acetate based emulsion adhesives And urethane resin emulsion adhesives, epoxy resin emulsion adhesives, polyester emulsion adhesives, ethylene-vinyl acetate copolymer adhesives, and the like. These may be used alone or in combination of two or more.

  The short fibers used for flocking are not particularly limited as long as they can be used as short fibers for flocking; for example, (1) polyolefin resins such as polyethylene and polypropylene, polyamide resins such as nylon, aromatic polyamide resins, polyethylene terephthalate Polyester resin such as polyethylene naphthalate, polyethylene succinate, polybutylene tephthalate, synthetic resin fiber such as acrylic resin, vinyl chloride, vinylon, (2) Carbon fiber, inorganic fiber such as glass fiber, (3) rayon, acetate etc And natural fibers such as cotton, silk, hemp, wool and the like. These may be used alone or in combination of two or more. Among the above, it is preferable to use a synthetic resin fiber because it is less likely to cause swelling or dissolution by oil, is chemically stable, can produce a large amount of homogeneous fibers, and can be obtained inexpensively.

  The shape of the synthetic resin fiber is not particularly limited. As a specific shape, for example, one having a length of 0.5 to 2.0 mm and a thickness of 0.5 to 50 dtex is preferable, and as the density of fibers in the flocked part, the ratio of the fibers per area of flocking Is preferably 1 to 40%. Further, as the shape of the short fiber, there are straight and bend (the tip of the fiber is bent) type, and the cross-sectional shape is circular and polygonal cross-sectional shape. By using the short fibers of the polygonal cross section, the surface area can be made larger than the short fibers of the circular cross section, and the retention of lubricating oil and the like is improved.

  A soft metal such as aluminum or aluminum alloy (A5052, A5056, A6063) is used as the material of the rotary shaft of each roller, which is the mating material of the slide bearing of the present invention.

  It is preferable to use a resin material as a bearing material forming the slide bearing of the present invention. Among resin materials, one or more thermoplastic resins selected from polyphenylene sulfide resin, aromatic polyether ketone resin, thermoplastic polyimide resin, polycyanoaryl ether resin, polyamide imide resin, polyether imide resin, and polyether sulfone resin It is preferable to use a resin as a base resin and a resin composition containing a polytetrafluoroethylene resin and lithium phosphate. As each mixture ratio, 35-74 weight% of thermoplastic resin, 10-45 weight% of polytetrafluoroethylene resin, and 16-30 weight% of lithium phosphates are preferable with respect to the whole resin composition, for example. By making the slide bearing a molded product of such a resin material, it is possible to form a transfer film having the required heat resistance and exhibiting good lubricity on the rotary shaft, and in particular even a soft aluminum alloy It does not damage the surface and exhibits good lubricating properties.

Among the thermoplastic resins, it is preferable to use a polyphenylene sulfide resin, an aromatic polyether ketone resin, or a thermoplastic polyimide resin.
In addition, when conductivity is required for the slide bearing in view of the structure of the fixing portion, it is possible to impart conductivity by adding carbon black, carbon nanotubes, or both to the resin composition. Although the compounding quantity of these is not particularly limited as long as it can impart desired conductivity, for example, it is compounded in an amount of 0.03 to 10% by weight with respect to the entire resin composition. The volume resistivity of the molded article of this resin composition is preferably 10 ³ Ω · cm or less. In addition, well-known resin additives may be added to the resin composition as long as the effects of the present invention are not impaired.

  In the sliding bearing according to the present invention, the grease or lubricating oil to be impregnated in the flocked portion and interposed on the sliding surface between the bearing surface and the rotating shaft is not particularly limited as long as torque can be reduced. Can be used. A slide bearing that supports a heat roller such as a fixing roller and a pressure roller of a fixing unit in an image forming apparatus needs heat resistance of 150 ° C. or more. It is preferable to use fluorine grease and urea grease having high heat resistance under such conditions. When the slide bearing needs to be conductive, it is preferable to use a conductive grease containing a conductive carbon or the like.

  The slide bearing of the present invention can reduce the friction between the bearing surface and the rotating shaft, can reduce the adverse effect of the generated wear powder, and is excellent in the supply and retention of grease etc. The present invention can be suitably used as a slide bearing for supporting the rotation shaft of a fixing roller of a fixing unit in an image forming apparatus such as a printer, a facsimile, etc. or a pressure roller.

DESCRIPTION OF SYMBOLS 1 slide bearing 2 bearing main body 3 bearing surface 4 rotating shaft 5 groove 6 fixing roller 7 pressure roller 8 peeling member 9 toner 10 sheet 11 spring 12 heater 13 inclined groove 14 flocked portion

Claims (6)

A sliding bearing comprising a bearing surface in contact with an outer peripheral surface of a rotating shaft, comprising:
The bearing surface is a cylindrical surface or a partial cylindrical surface along the outer peripheral surface of the rotating shaft,
The bearing surface has one or a plurality of grooves along the axial direction of the rotating shaft at a portion in sliding contact with the rotating shaft to receive a load,
A slide bearing characterized by having a flocked portion in which fibers are flocked in the groove.   The slide bearing according to claim 1, wherein the flocking portion is impregnated with a lubricant.   The plain bearing according to claim 1 or 2, wherein a tip of the fiber is in contact with the rotation shaft.   In the bearing surface, an offset load in a non-perpendicular direction is loaded with respect to the axis of the rotary shaft, and an axial end of the axial end of the bearing surface on the side where the load received by the offset load is large, The slide bearing according to any one of claims 1 to 3, further comprising an inclined groove formed to expand the diameter of the bearing surface toward the axial outer side of the end.   The slide bearing according to any one of claims 1 to 4, wherein the fiber is a synthetic resin fiber.   The slide bearing according to any one of claims 1 to 5, wherein the slide bearing is a bearing that supports a rotation shaft of a fixing roller or a pressure roller in an image forming apparatus.

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