JP2019158122A - Slide bearing - Google Patents

Abstract

To provide a slide bearing which can reduce an adverse effect caused by wear powder produced by the rotation of a rotating shaft, and can maintain a favorable slide state on a slide face, in the slide bearing in which a radial load vertical to an axial line of the rotating shaft is applied on the bearing face.SOLUTION: A slide bearing 1 comprises a bearing face 3 contacting with an external peripheral face of a rotating shaft 4, and a non-contact face not contacting with the external peripheral face of the rotating shaft 4 at a bearing inner face side. A radial load vertical to an axial line of the rotating shaft 4 is applied on the bearing face 3. The slide bearing has a flock part 5 in which organic fibers such as synthetic resin fibers are flocked at the non-contact face.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sliding bearing. In particular, a slip applied to an application for supporting a rotating shaft of a fixing roller, a pressure roller, or the like of a fixing unit in an image forming apparatus such as a copying machine, a multifunction machine, a printer (laser beam printer, an inkjet printer, etc.) or a facsimile. Related to bearings.

  A fixing device of an image forming apparatus such as a copying machine or a printer fixes unfixed toner transferred from a photosensitive drum to a sheet by heat and pressure. The fixing device applies heat and pressure at the same time by allowing the paper to enter between a fixing roller with a built-in heat source such as a halogen heater or a ceramic heater in a cylinder and a pressure roller installed opposite to the fixing roller. A mechanism for fixing 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. Further, 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 through 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 this bearing, a ball bearing (rolling bearing), a sintered oil-impregnated bearing, a resin sliding bearing, or the like is used. As a resin sliding bearing used for such an application, a U-shaped or cylindrical shape having an opening is often used, and grease is often applied to the bearing surface during use.

  Copiers and printers are becoming increasingly faster and more energy efficient year after year, and bearings are required to handle high loads and high speed conditions, lower torque, and improve 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 sliding bearings, but they are expensive. Although the sintered oil-impregnated bearing is low in cost, it has a disadvantage that the degree of freedom in design is lower than that of a resin sliding bearing that can be injection molded. For this reason, application of a resin sliding bearing is desired even in a so-called high-end model having a high printing speed.

  As a method of reducing the contact area between the bearing surface of the resin sliding bearing and the rotating shaft, by setting the axial length of the portion where the bearing surface contacts the rotating shaft shorter than the total axial length of the sliding bearing, A method for reducing torque has been proposed (see Patent Document 1).

  In addition, for the purpose of improving lubrication characteristics including reduction of rotational torque of the bearing, there is provided a rolling bearing in which a flocked portion formed by flocking fibers is formed on a surface that comes into contact with the lubricant other than the contact surface with the rolling element. It has been proposed (see Patent Document 2).

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

  However, with the recent increase in printing speed of image forming apparatuses, the required characteristics for bearings have become more severe. For example, a reduction in bearing diameter is required for cost reduction. Since the reduction of the bearing diameter is also the reduction of the diameter of the shaft, the shaft is bent due to the increased load, and contact between the bearing and the shaft cannot be received over the entire bearing width. As a result, during initial use of the bearing, there is a problem that a large amount of wear powder is generated in the bearing because it receives a load at the bearing edge. Further, the generated wear powder is held by grease, and there is a problem that the friction wear is adversely affected by virtue of the vicious cycle in which the bearing is further worn by the held wear powder.

  In general, when a grease groove is formed in a load section or a flocked part for the purpose of improving the retention of grease, etc., the effect may be adversely affected depending on the shape, position, and usage conditions. There is a risk that sufficient effects cannot be obtained.

  The present invention has been made to cope with these problems, and includes a bearing surface that contacts the outer peripheral surface of the rotating shaft and a non-contact surface that does not contact the outer peripheral surface of the rotating shaft, and is provided with respect to the axis of the rotating shaft. It is an object of the present invention to provide a sliding bearing that can reduce the adverse effects of abrasion powder generated by shaft rotation and maintain a good sliding state on the bearing surface in a sliding bearing that is vertically loaded with a radial load.

  The sliding bearing of the present invention includes a bearing surface that contacts the outer peripheral surface of the rotating shaft, and a non-contact surface that does not contact the outer peripheral surface of the rotating shaft on the inner surface of the bearing, and is a radial that is perpendicular to the axis of the rotating shaft. A sliding bearing in which a load is applied to the bearing surface, wherein the non-contact surface has a flocked portion in which organic fibers are flocked.

  As a first form of the bearing, the bearing surface is a U-shaped bottom portion side of a U-shaped bearing in cross section, and the non-contact surface is a bearing surface on both ends where the U-shaped bearing is open. As a second form of the bearing, the bearing surface is on the inner bottom side of the cross-sectional cylinder having a diameter larger than that of the rotating shaft, and the non-contact surface is on the inner top side of the cross-sectional cylinder.

  The organic fiber planted in the planted part is a synthetic resin fiber. According to another aspect of the present invention, there is provided a sliding bearing that supports a rotating shaft of a fixing roller or a pressure roller in an image forming apparatus.

  Since the sliding bearing of the present invention has a flocked portion in which organic fibers are flocked on a non-contact surface, the abrasion powder generated and carried on the bearing surface which is a load-loading portion by shaft rotation again becomes a load-loading portion. It is caught at the flocked portion without being carried, and adverse effects such as a decrease in friction and wear characteristics can be prevented. Further, since the grease held in the flocked portion is appropriately conveyed to the load applying portion by the shaft rotation, a low friction coefficient and a low torque can be maintained. For this reason, even when used as a sliding bearing for supporting the rotating shaft of a roller such as a fixing roller or a pressure roller of a fixing unit in an image forming apparatus such as a copying machine, a multifunction machine, a printer, or a facsimile, the bearing surface is good. Can maintain a stable sliding state.

It is a figure which shows an example of the slide bearing of this invention. It is a figure which shows an example of the other slide bearing of this invention. 2 is a schematic diagram of a configuration of a fixing unit of the image forming apparatus. FIG.

  The configuration of the fixing unit of the image forming apparatus using the slide bearing of the present invention will be described with reference to FIG. FIG. 3 is a schematic diagram of the configuration of the fixing unit. The image forming apparatus forms an image captured by an optical unit with toner on a transfer belt at a developing unit and a photosensitive unit. As shown in FIG. 3, in the fixing unit, the toner 9 is transferred onto the paper 10 and printed on the paper 10. At that time, the paper 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. A peeling member 8 is provided at a position in contact with or close to the fixing roller 6 so that the paper 10 that has passed through the nip portion can be peeled from the fixing roller 6.

  Heat is transferred to the fixing roller 6 via a belt, or a heater is built in, so that the fixing roller 6 has a high temperature. The fixing roller 6 and the pressure roller 7 are rotatably supported by bearings at their respective rotation shafts. Here, the pressure roller 7 is pressed against the fixing roller 6 by a spring 11 or the like via the sliding bearing 1 of the present invention. For this reason, the sliding bearing 1 that supports the rotating shaft 4 of the pressure roller 7 always receives a load in one direction (a load in a direction perpendicular to the axis of the rotating shaft 4). When the printing speed is increased, since it is necessary to burn the toner in a short time, both the temperature of the fixing roller 6 and the pressing force of the pressure roller 7 are increased, and the use conditions of the bearing become severe.

An example of the sliding bearing of the present invention will be described with reference to FIG. FIG. 1 shows a U-shaped bearing, FIG. 1 (a) is a perspective view, and FIG. 1 (b) is an AA cross-sectional view shown with a shaft.
As shown in FIGS. 1 (a) and 1 (b), a plain bearing 1 is composed of a bearing body 2 having a U-shaped section having a predetermined axial thickness, and a rotating shaft such as a pressure roller is provided on the bearing body 2. 4 has a bearing surface 3 in contact with and supporting the outer peripheral surface of 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 radial cross section of the bearing surface 3 has an arc shape. The shape of the cross section of the bearing surface 3 is the same in the entire range in the axial direction. The diameter of the rotating shaft 4 supported by the slide bearing 1 is slightly smaller than the distance between the inner wall surfaces 2a and 2b of the bearing body 2. In this form, it has the flocked part 5 in which the organic fiber was flocked to the upper part of the open U-shaped inner wall surface 2a, 2b. In the U-shaped bearing, the flocked portion 5 is provided on both end bearing surfaces that do not contact the outer peripheral surface of the rotating shaft 4.

Another example of the slide bearing of the present invention will be described with reference to FIG. FIG. 2 shows a cross-sectional cylindrical bearing having a bearing surface having a diameter larger than that of the rotating shaft, FIG. 2 (a) is a perspective view, and FIG. 2 (b) is a BB cross-sectional view shown with the shaft.
As shown in FIGS. 2 (a) and 2 (b), the sliding bearing 1 'is composed of a cylindrical bearing body 2' having a predetermined axial thickness, and a pressure roller or the like is provided on the bearing body 2 '. It has a bearing surface 3 ′ in contact with and supporting the outer peripheral surface of the rotating shaft 4. The bearing surface 3 ′ is formed on the inner bottom side of the bearing body 2 ′. The bearing surface 3 ′ is a partial cylindrical surface (arc surface) along the outer peripheral surface of the rotating shaft 4. The radial cross section of the bearing surface 3 'has an arc shape. The shape of the cross section of the bearing surface 3 ′ is the same in the entire range in the axial direction. The diameter of the rotating shaft 4 supported by the sliding bearing 1 ′ is slightly smaller than the diameter of the bearing body 2 ′. Therefore, a radial load perpendicular to the axis of the rotating shaft 4 is applied to the bearing surface 3 ′, so that a space corresponding to the diameter difference between the bearing body 2 ′ and the rotating shaft 4 is provided on the inner top side 3 ″ of the cross-sectional cylinder. Can do. That is, a space portion is formed on the inner top side 3 ″ that is the opposite load side to the bearing surface 3 ′. This inner top side 3 ″ is a non-contact surface that does not contact the outer peripheral surface of the rotating shaft 4. In this form, it has the flocked part 5 in which the organic fiber was flocked on the surface on the inner top side.

  By providing the flocked portion 5, the wear powder generated on the bearing surface 3 or 3 ′ is organically transferred to the bearing surface 3 or 3 ′, which is a load-loading portion, by the rotation of the rotating shaft 4. By being caught between the system fibers and held there, adverse effects on frictional wear can be prevented.

  The organic fiber can physically hold the wear powder between the fibers and can also be held by the action of static electricity. Organic fibers include polyolefin resins such as polyethylene and polypropylene, polyamide resins such as nylon, aromatic polyamide resins, polyethylene terephthalate, polyethylene naphthalate, polyethylene succinate, polyester resins such as polybutylene terephthalate, acrylic resins, vinyl chloride And synthetic resin fibers such as vinylon, regenerated fibers such as rayon and acetate, and natural fibers such as cotton, silk, hemp and wool. Of these, synthetic resin fibers are preferable.

  The shape of the synthetic resin fiber is not particularly limited as long as it is a short fiber shape that does not interfere with other members that adversely affect the bearing function when flocked to a non-contact surface. As a specific shape, for example, those having a length of 0.5 to 2.0 mm and a thickness of 0.5 to 50 dtex are preferable, and the density of the fibers in the flocked portion is the ratio of the fibers to the flocked area Is preferably 1 to 40%. The short fiber has a straight type and a bend type (a fiber tip is bent), and a cross-sectional shape includes a circular shape and a polygonal cross-sectional shape.

  The flocked portion 5 can be formed by flocking a short fiber on the surface of the non-contact surface, for example. Spraying or electrostatic flocking can be employed as a flocking coating method. It is preferable to employ electrostatic flocking because a large amount of fibers can be densely and vertically planted in an arbitrary position on the surface of the non-contact surface in a short time. As the electrostatic flocking method, a known method can be adopted. For example, as an electrostatic flocking method, (1) a step of applying an adhesive to a range where the sliding bearing 1 or 1 ′ is subjected to electrostatic flocking; (2) electrostatic charging by spraying charged short fibers on the non-contact surface of the sliding bearing; (3) drying the surface on which the short fibers are temporarily attached, sufficiently curing the adhesive, and fixing the short fibers to the surface of the non-contact surface. A method including a process etc. is mentioned.

  Examples of the adhesive that can be used for electrostatic flocking include an adhesive mainly composed of urethane resin, epoxy resin, acrylic resin, vinyl acetate resin, polyimide resin, silicone resin, and the like. For example, urethane resin solvent adhesive, epoxy resin solvent adhesive, vinyl acetate resin solvent adhesive, acrylic resin emulsion adhesive, acrylate-vinyl acetate copolymer emulsion adhesive, vinyl acetate emulsion adhesive , Urethane resin emulsion adhesive, epoxy resin emulsion adhesive, polyester emulsion adhesive, ethylene-vinyl acetate copolymer adhesive and the like. These may be used alone or in combination of two or more.

  A soft metal such as aluminum or aluminum alloy (A5052, A5056, A6063) is used as the material of the rotating shaft of each roller which is a counterpart of the sliding bearing of the present invention.

  A resin material is preferably used as the bearing material forming the sliding bearing of the present invention. Among the resin materials, at least one thermoplastic selected from polyphenylene sulfide resin, aromatic polyether ketone resin, thermoplastic polyimide resin, polycyanoaryl ether resin, polyamideimide resin, polyetherimide resin, and polyethersulfone resin. It is preferable to use a resin composition containing a resin as a base resin and containing a polytetrafluoroethylene resin and lithium phosphate. As each compounding ratio, for example, 35 to 74% by weight of thermoplastic resin, 10 to 45% by weight of polytetrafluoroethylene resin, and 16 to 30% by weight of lithium phosphate are preferable with respect to the entire resin composition. By making the slide bearing into a molded body of such a resin material, it is possible to form a transition film on the rotating shaft that has the required heat resistance and good lubricity, even if it is a soft aluminum alloy. It shows good lubrication properties without damaging the surface.

Among the thermoplastic resins, it is preferable to use polyphenylene sulfide resin, aromatic polyether ketone resin, or thermoplastic polyimide resin.
If the sliding bearing requires conductivity due to the structure of the fixing portion, conductivity can be imparted by adding one or both of carbon black and carbon nanotube to the resin composition. Although these compounding quantities will not be specifically limited if it is the quantity which can provide desired electroconductivity, For example, 0.03 to 10 weight% is mix | blended with respect to the whole resin composition. The volume resistivity of the molded body of this resin composition is preferably 10 ³ Ω · cm or less. In addition, a known resin additive may be added to the resin composition to the extent that the effects of the present invention are not impaired.

  In the sliding bearing of the present invention, it is preferable that a lubricant such as grease or lubricating oil is interposed in the sliding portion between the bearing surface and the rotating shaft that is the counterpart material. By interposing a lubricant in the sliding portion, torque can be reduced, wear can be suppressed, and the performance life is greatly extended. In addition, since some of the grease is also held in the flocked portion provided on the non-contact surface, oil oozes out from the flocked portion and is appropriately supplied to the load-loading portion, so that the performance life can be further extended.

  The grease and lubricating oil are not particularly limited as long as the torque can be reduced, and those usually used for sliding bearings can be used. A sliding bearing that supports a heat roller such as a fixing roller or a pressure roller of a fixing unit in an image forming apparatus needs to have a heat resistance of 150 ° C. or higher. Under such conditions, it is preferable to use fluorine grease or urea grease having high heat resistance. In addition, when the slide bearing needs conductivity, it is preferable to use conductive grease containing conductive carbon or the like.

  The sliding bearing of the present invention can reduce the adverse effects of abrasion powder generated on the bearing surface and the rotating shaft, and can maintain a good sliding state on the bearing surface, so images of copying machines, multifunction machines, printers, facsimiles, etc. It can be suitably used as a sliding bearing that supports a rotating shaft of a fixing roller or a pressure roller of a fixing unit in the forming apparatus.

DESCRIPTION OF SYMBOLS 1, 1 'Sliding bearing 2, 2' Bearing main body 3, 3 'Bearing surface 4 Rotating shaft 5 Flocking part 6 Fixing roller 7 Pressure roller 8 Peeling member 9 Toner 10 Paper 11 Spring

Claims (5)

A bearing surface that contacts the outer peripheral surface of the rotating shaft and a non-contact surface that does not contact the outer peripheral surface of the rotating shaft are provided on the inner surface of the bearing, and a radial load perpendicular to the axis of the rotating shaft is applied to the bearing surface. A sliding bearing,
A sliding bearing having a flocked portion in which organic fibers are flocked on the non-contact surface.   The plain bearing according to claim 1, wherein the bearing surface is a U-shaped bottom side of a U-shaped bearing in cross section, and the non-contact surface is a bearing surface on both ends opened by the U-shaped bearing.   2. The plain bearing according to claim 1, wherein the bearing surface is an inner bottom side of a cross-sectional cylinder having a larger diameter than the rotating shaft, and the non-contact surface is an inner top side of the cross-sectional cylinder.   The sliding bearing according to any one of claims 1 to 3, wherein the organic fibers are synthetic resin fibers.   The sliding bearing according to any one of claims 1 to 4, wherein the sliding bearing is a bearing that supports a rotating shaft of a fixing roller or a pressure roller in the image forming apparatus.

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