JP2011074975A - Slide bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost slide bearing having a simple configuration and capable of maintaining low friction torque. <P>SOLUTION: This slide bearing 1 supports a heat roller such as a fixing roller and a pressing roller of an image forming device. The slide bearing 1 comprises an outer ring 3 and an inner ring 2. One of the outer ring 3 and the inner ring 2 is made of synthetic resin and another is made of sintered metal. An outer peripheral surface of the inner ring 2 is a convex curved surface and an inner peripheral surface of the outer ring 3 is a concave curved surface corresponding to the convex curved surface. The outer ring 3 is a shape divided into two in a radial direction. The inner ring 2 is put between the two divided outer rings 3. The inner peripheral surface of the outer ring 3 and the outer peripheral surface of the inner ring 2 are in sliding contact relatively. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sliding bearing, and more particularly to a sliding bearing used for supporting a heated roller (heat roller) such as a fixing roller or a pressure roller of a fixing device in an image forming apparatus such as a copying machine, a printer, and a facsimile machine.

  In general, an image forming apparatus has a fixing device in which toner is attached to an electrostatic latent image formed by an optical device, and the toner image is transferred to a copy sheet and further fixed. In this fixing step, the toner image is passed between a fixing roller incorporating a heater and a pressure roller. As a result, the transfer image composed of the toner image is fixed on the copy sheet by heat fusion.

  The fixing roller is made of a soft metal in which a linear or rod-shaped heater is incorporated in the shaft center portion, and is formed in a cylindrical shape in which a small-diameter shaft portion projects from both ends. The fixing roller is made of a metal material having excellent thermal conductivity such as aluminum or aluminum alloy (A5056, A6063). The surface of the fixing roller is finished by turning or polishing. The fixing roller surface is coated or covered with a non-adhesive resin such as a fluororesin. The surface temperature of the fixing roller is heated to about 180 to 250 ° C. by a heater.

  The pressure roller is made of an iron material or a soft material coated with silicon rubber or the like, and is driven to rotate by pressing a copy sheet against the fixing roller. The pressure roller is heated to about 70 to 150 ° C. by heat transfer from the heating roller. Alternatively, like the fixing roller, a heater is provided inside and heated to about 150 to 250 ° C.

  Hereinafter, a roller that is heated by heat transfer from a built-in heater or another member, such as the above-described fixing roller and pressure roller, is referred to as a “heat roller”.

  A heat roller heated to a high temperature is rotatably supported by a housing via a rolling bearing formed of a deep groove ball bearing at both end shaft portions, and a synthetic resin is interposed between the rolling bearing and the shaft portion of the heat roller. A heat insulating sleeve made up of, etc. is interposed. This is to prevent the heat from escaping from the rolling bearings at both ends during heating of the heat roller to prevent the temperature distribution along the axial direction of the heat roller from becoming non-uniform and to prevent the bearing from deteriorating at high temperatures.

  In addition, as a support roller for the heat roller, there is one using a resin sliding bearing. For example, the sliding bearing is formed from a synthetic resin such as polyphenylene sulfide (hereinafter referred to as PPS) resin, polyamide resin, polyamideimide resin, polyimide (hereinafter referred to as PI) resin, or polyetheretherketone resin. As a specific example, a PPS resin having excellent heat resistance and mechanical strength is used as a ring-shaped bearing body, a fluororesin layer is adhered to the sliding surface, or a PPS resin blended with a fluororesin is used. A technique for integrally molding the entire plain bearing is known (see Patent Document 1).

  When using a resin sliding bearing, the resin sliding bearing itself has a heat insulating property, and therefore, generally, a heat insulating sleeve is not interposed between the resin sliding bearing and the shaft portion of the heat roller. Usually, in a fixing device of an image forming apparatus, a rolling bearing is used as a heat roller bearing for intermediate to high-end machines, and a plastic sliding bearing is used for a popular machine.

Japanese Patent Laid-Open No. 5-117678

  However, the deep groove ball bearing, which is a bearing for the heat roller of the fixing device in the image forming apparatus described above, has a complicated structure and is expensive to manufacture. Further, in order to prevent non-uniform temperature distribution and high temperature deterioration of the bearing, the above-described resin heat insulating sleeve is required, which further increases the cost. In addition, there is a problem in quality such that the bearing is damaged by moment load such as deflection of the support shaft of the heat roller and mounting accuracy.

  On the other hand, a plastic sliding bearing such as a PPS resin can be used without interposing a heat insulating sleeve, and has an advantage that it can be produced at low cost because it has a simple structure and can be injection-molded. However, this resin sliding bearing has a problem that the friction torque is about 2 to 5 times as high as that of the deep groove ball bearing. In particular, when the bearing surface of the heat roller is rough, there is a problem that the friction torque is further increased, and at the same time, wear is increased and the specification cannot be satisfied.

  Even if grease is applied to the bearing sliding surface in order to reduce the friction torque, there is a case where the grease is insufficient in a portion that receives a strong load and the specification cannot be satisfied.

  The present invention has been made in order to cope with such a problem, and an object thereof is to provide a plain bearing that has a low-cost and simple structure and can maintain a low friction torque.

  The sliding bearing of the present invention comprises an outer ring and an inner ring, and either the outer ring or the inner ring is made of synthetic resin and the other is made of sintered metal, and the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring And are relatively in sliding contact with each other. In particular, the sliding bearing is a bearing that supports a heat roller, and the heat roller is a heater built in the heat roller or a roller heated by heat transfer from another member.

  The outer peripheral surface of the inner ring is a convex curved surface, and the inner peripheral surface of the outer ring is a concave curved surface corresponding to the convex curved surface. Further, the outer ring has a shape divided into two in the radial direction, and the inner ring is sandwiched between the outer rings divided into two, so that the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring are relatively It is incorporated so as to be in sliding contact.

  As another aspect, the outer ring has inner ring incorporating grooves formed at two opposing locations on the inner peripheral surface thereof, and the inner ring incorporating groove is formed to open at least one end surface of the outer ring. The inner ring is incorporated into the outer ring through the inner ring incorporating groove. The inner ring is inserted into the outer ring through the inner ring mounting groove in a state in which the axis of the inner ring is shifted from the axis of the outer ring, and then the inner ring and the outer ring are relatively rotated to rotate the inner ring. The shaft center of the outer ring and the shaft center of the outer ring are combined to be incorporated in the outer ring.

  Grease is enclosed between the inner ring and the outer ring, and a grease holding recess for holding the grease is formed on the outer peripheral surface of the inner ring. The depth of the grease retaining recess is 0.03 to 0.7 mm at the deepest portion.

  The grease retaining recess is an inverted conical dimple having a diameter of 0.3 to 2.0 mm, which is provided in plural on the entire outer circumference of the inner ring. The dimple has an opening angle of 10 to 45 degrees.

  The grease retaining recess is a plurality of two rows of rectangular grooves having a C shape provided on the entire outer circumference of the inner ring, and is formed so that the lower side of the H shape faces the rotation direction of the inner ring. It is characterized by being. Further, the plurality of rectangular grooves are inclined grooves in which the grooves deepen from the rectangular side on the rotation direction side toward the opposite side.

  The synthetic resin is a resin composition containing a solid lubricant. The base resin of the resin composition is a PPS resin.

  The sintered metal contains at least one selected from copper (hereinafter referred to as Cu) and iron (hereinafter referred to as Fe) as a main component.

  The grease is at least one selected from fluorine grease and urea grease.

  The sliding bearing of the present invention comprises an outer ring and an inner ring, and either the outer ring or the inner ring is made of synthetic resin and the other is made of sintered metal, and the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring Therefore, the number of parts is small and the structure is simple compared to conventional rolling bearings. Thus, the manufacturing process can be simplified and the manufacturing cost can be reduced. In addition, since either the outer ring or the inner ring is made of synthetic resin, the heat insulation effect is high and the heat efficiency of the heat roller does not decrease. Moreover, since the other of the outer ring or the inner ring is made of sintered metal, the heat dissipation effect is high and the bearing life is long. Furthermore, since it is composed of an outer ring and an inner ring, it can be formed in the same size as a conventional rolling bearing, and it can be replaced with a rolling bearing and is compatible.

  The sliding bearing can be suitably used as a built-in heater or a bearing that supports a heat roller heated by heat transfer from another member, for example, a fixing roller or a pressure roller in an image forming apparatus.

  Further, since the outer peripheral surface of the inner ring is a convex curved surface and the inner peripheral surface of the outer ring is a concave curved surface corresponding to the convex curved surface, it is possible to impart alignment to the outer ring with respect to the inner ring. For this reason, the bearing is not damaged even if the support shaft is bent due to the mounting accuracy of the support shaft of the heat roller or the moment load.

  Further, the outer ring has a shape divided into two in the radial direction, and the inner ring is sandwiched between the outer rings divided into two, and is incorporated so that the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring are in sliding contact. Therefore, it can be easily assembled to the support shaft. In particular, even when the outer peripheral surface of the inner ring is a convex curved surface and the inner peripheral surface of the outer ring is a concave curved surface corresponding to the convex curved surface, the assemblability to the support shaft is excellent.

  Further, the outer ring has an inner ring incorporating groove formed at two opposite positions on the inner peripheral surface thereof, and the inner ring incorporated groove is formed to open at least one end surface of the outer ring. Since the inner ring is incorporated into the outer ring via the inner ring incorporating groove, the inner ring can be incorporated into the outer ring without dividing the outer ring. In addition, the inner ring is assembled into the outer ring by inserting the inner ring into the outer ring through the inner ring assembling groove with the inner and outer rings axially displaced, and then rotating the inner and outer rings relative to each other to align the axes. So it can be installed without elastic deformation of inner and outer rings.

  Further, grease is sealed between the inner ring and the outer ring, and a grease holding recess for holding the grease is formed on the outer peripheral surface of the inner ring, so that the grease is held in the grease holding recess and the friction torque can be kept low. . Moreover, since the depth of the grease retaining recess is 0.03 to 0.7 mm at the deepest portion, the grease can be retained in the grease retaining recess sufficiently and without waste.

  Further, since the grease holding recesses are inverted conical dimples having a diameter of 0.3 to 2.0 mm provided on the entire circumference of the outer peripheral surface of the inner ring, grease can be supplied to the sliding surface by the wedge effect. . Moreover, since the approach angle of the opening portion of the inverted conical dimple is 10 to 45 degrees, the wedge effect is enhanced.

  Further, the grease retaining recess is a plurality of two rows of rectangular grooves having a C shape provided on the entire circumference of the outer peripheral surface of the inner ring, and is formed so that the lower side of the C shape faces the rotation direction of the inner ring. Therefore, when the inner ring rotates, the grease is always scraped from the lower side of each groove to the upper side, that is, the central part in the bearing width direction. Therefore, a film made of grease is easily and continuously formed in the center portion in the bearing width direction where the bearing receives the most load, and smooth rotation with low friction torque can be obtained. In addition, since the plurality of rectangular grooves are inclined grooves whose grooves deepen from the rectangular side on the rotation direction side toward the opposite side, the grease is easily scraped and the above-described effect is improved.

  Moreover, since the synthetic resin forming one of the outer ring and the inner ring is a resin composition containing a solid lubricant, the rotational torque is stabilized even without lubrication. Even in the case of grease lubrication, when the grease runs out, the rotational torque does not increase abnormally.

  Further, since the base resin of the resin composition is a PPS resin, it can be used for supporting the fixing roller and the pressure roller in the image forming apparatus without interposing a heat insulating sleeve. Moreover, since it can be injection-molded, it can be produced at low cost.

  Moreover, since the sintered metal which forms the other of an outer ring | wheel or an inner ring | wheel is a sintered metal which has Cu or Fe or both as a main component, it is excellent in heat dissipation. In addition, it can be easily manufactured by compression molding, and can be produced at low cost with little dimensional change.

  Further, since the grease to be enclosed is at least one selected from fluorine grease and urea grease, even if it is used as a sliding bearing for supporting the heat roller, the life of the sliding bearing can be extended. Even when the fixing roller in the image forming apparatus is supported, there is no deterioration with respect to the fixing temperature.

  In addition, since the inner ring is made of sintered metal and the outer ring is made of synthetic resin, the entire bearing is hardly affected by thermal expansion, and uneven wear of the outer ring does not occur. Further, the heat efficiency of the heat roller does not decrease by making the inner ring made of synthetic resin and the outer ring made of sintered metal. For this reason, energy cost can be suppressed low.

It is a perspective view of a slide bearing as one embodiment of the present invention, and a perspective view showing a state before union of inner and outer rings. It is a front view which shows an example of the grease holding | maintenance recessed part provided in the sliding surface of the inner ring | wheel outer periphery of a slide bearing. FIG. 3 is an enlarged cross-sectional view of a grease holding recess in FIG. 2. It is a perspective view which shows the other example of the grease holding | maintenance recessed part provided in the sliding surface of the inner ring | wheel outer periphery of a slide bearing. FIG. 5 is a partially enlarged perspective view of a grease holding recess in FIG. 4. It is a schematic diagram of a shaft heating type high temperature radial testing machine. It is a perspective view which shows the other aspect of the slide bearing of this invention.

  In the sliding bearing of the present invention, either the outer ring or the inner ring is made of synthetic resin. Although the kind of synthetic resin is not specifically limited, it is necessary to be a synthetic resin having characteristics that meet at least the use conditions (heat resistance, mechanical strength, etc.) of the sliding bearing. Moreover, if it is a synthetic resin which can be injection-molded, it can be manufactured easily and the dimensional accuracy can be made uniform, which is preferable in managing the fitting gap.

  Examples of synthetic resins include polyacetal (POM) resin, nylon resin (nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, nylon 46, semi-aromatic nylon having an aromatic ring in the molecular chain. Etc.), injection of polytetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA) resin, tetrafluoroethylene / hexafluoropropylene copolymer (FEP) resin, ethylene-tetrafluoroethylene copolymer (ETFE) resin, etc. Examples thereof include a moldable fluororesin, an injection moldable PI resin, a PPS resin, a wholly aromatic polyester resin, a PEEK resin, and a polyamideimide resin. Each of these synthetic resins may be used alone or may be a polymer alloy in which two or more kinds are mixed. Or the polymer alloy which mix | blended said synthetic resin with the synthetic resin with low lubrication characteristics other than the above may be sufficient.

  Among these synthetic resins, it is preferable to use a PPS resin that is excellent in heat resistance and mechanical strength and relatively inexpensive. By using the PPS resin, the sliding bearing of the present invention can be suitably used for a sliding bearing that supports a fixing roller or the like that operates at a high temperature of the image forming apparatus.

  Moreover, glass fibers, carbon fibers, and various mineral fibers (whiskers) may be added to these synthetic resins to increase the strength. In addition, it is possible to improve the lubrication characteristics by adding a solid lubricant or the like to these synthetic resins. Examples of the solid lubricant include polytetrafluoroethylene (hereinafter referred to as PTFE) resin, graphite, and molybdenum disulfide.

  In the sliding bearing of the present invention, the other of the outer ring and the inner ring made of the synthetic resin is made of sintered metal. Although the kind of sintered metal is not particularly limited, for example, Fe-based, Cu-based, Fe-Cu-based, Cu-tin (hereinafter referred to as Sn) -based, or Cu-Fe-Sn-based alloys can be used. Moreover, what added carbon, graphite, molybdenum disulfide, etc. as a sliding material to these can also be used. Among these sintered metals, it has excellent heat dissipation, is easy to manufacture by compression molding, and can be produced at low cost with little dimensional change. Therefore, it should contain at least one selected from Cu and Fe as a main component. Is preferred.

  In the sliding bearing of the present invention, when a sintered metal is used for the inner ring and a synthetic resin is used for the outer ring, the entire sliding bearing is hardly affected by thermal expansion, and uneven wear of the outer ring does not occur. Further, when a synthetic resin is used for the inner ring and a sintered metal is used for the outer ring, it is possible to suppress a decrease in the heat efficiency of the heat roller, and to reduce the energy cost of the fixing device.

  An embodiment of the slide bearing of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a sliding bearing of the present invention and a perspective view showing a state before the inner and outer rings are combined. The sliding bearing 1 of the present invention is composed of only an inner ring 2 (the whole view is FIG. 2 or FIG. 4) and an outer ring 3, and the inner peripheral surface of the outer ring 3 and the outer peripheral surface of the inner ring 2 are in sliding contact with each other. The sliding surface of the inner peripheral surface of the outer ring 3 and the outer peripheral surface of the inner ring 2 may be a cylindrical shape that is flat in the axial direction. However, as shown in FIG. By forming the peripheral surface with a concave curved surface corresponding to the convex curved surface, the sliding bearing 1 can be aligned. In this case, the outer peripheral surface of the inner ring 2 having the convex curved surface is formed as a parting surface (parting line) in the injection molding of the inner ring by making the entire circumference of the central portion (maximum diameter portion) in the width direction of the inner ring 2 flat. Even if (PL)) is set at the central portion (maximum diameter portion) in the width direction of the inner ring 2, it is not necessary to post-process the PL trace.

  As shown in FIG. 1, in the sliding bearing 1, the outer ring 3 has a shape divided into two in the radial direction, and the inner ring 2 is sandwiched between the outer ring lower part 3a and the outer ring upper part 3b of the outer ring 3 divided into two parts. The inner ring surface of the outer ring 3 and the outer ring surface of the inner ring 2 are assembled in sliding contact.

  As shown in FIG. 1, a key 3c and a key groove 3d on one side of the split surface divided in the radial direction of the outer ring lower part 3a are provided at the left and right target positions, and the split surface of the outer ring upper part 3b corresponds to these. A keyway and a key are provided. By doing in this way, the outer ring | wheel lower part 3a and the outer ring | wheel upper part 3b can be used as a common molded object. Moreover, even if it is an outer ring | wheel with a flange as shown in FIG. The outer ring lower part 3a and the outer ring upper part 3b are combined in such a manner that after the inner ring 2 is assembled to the outer ring lower part 3a, the key 3c of the outer ring lower part 3a is used as the key groove of the outer ring upper part 3b, and the key groove 3d of the outer ring lower part 3a is used. This can be done easily by fitting the key.

  Although the outer ring 3 has been described by exemplifying the case of two divisions, it can be divided into three or more divisions. Moreover, the structure which does not divide | segment an outer ring | wheel may be sufficient as long as an inner ring | wheel can be integrated. For example, as shown in FIG. 7, the sliding bearing 1 includes an outer ring 3 having a concave curved inner peripheral surface in which inner ring incorporating grooves 3 e are formed at two opposing positions on the inner peripheral surface, and a convex curved surface corresponding to the concave curved surface. The structure which consists of the inner ring | wheel 2 which has these outer peripheral surfaces may be sufficient. With such a structure, the inner ring 2 and the outer ring 3 are relatively rotated after the inner ring 2 is inserted into the outer ring 3 from the inner ring mounting groove 3e with the axis of the inner ring 2 and the axis of the outer ring 3 shifted by 90 degrees. The inner ring 2 can be incorporated into the outer ring 3 by aligning the axis of the inner ring 2 and the axis of the outer ring 3.

  When grease lubrication is employed, it is preferable to form a grease retaining recess on one or both of the inner ring and the outer ring so that grease can be held and supplied to the sliding surface. The design of the grease retaining recess is set so that the grease does not leak from the sliding bearing 1 within the sliding surfaces of the inner ring 2 and the outer ring 3. When the grease retaining recess is formed in the inner ring 2, it is preferable that the inner ring 2 in which grease is sufficiently applied (enclosed) in advance in the grease retaining recess is assembled in the outer ring 3 during assembly.

  The depth of the grease retaining recess is preferably 0.03 to 0.7 mm at the deepest portion. The depth is the distance from the outer peripheral surface (front surface) of the inner ring 2 to the bottom of the concave portion. When the bottom of the concave portion is inclined, the depth of the deepest portion (the deepest portion) is within the above range. It is preferable to do. If the depth of the recess is less than 0.03 mm, the recess is too shallow to hold sufficient grease for lubrication. On the other hand, if the depth of the recess exceeds 0.7 mm, the recess becomes too deep and grease accumulates at the bottom of the recess, increasing the amount of grease that does not contribute to lubrication.

  An example of a preferable grease retaining recess is a dimple as shown in FIG. FIG. 3 is a sectional view of the dimple portion. A plurality of dimples 4 that are grease retaining recesses shown in FIGS. 2 and 3 are provided in the entire circumference of the outer peripheral surface of the inner ring 2 and have an inverted conical shape having a predetermined diameter R. Since the dimple 4 has an inverted conical shape, the grease can be efficiently supplied to the lubricating surface by the wedge effect accompanying the rotation of the inner ring 2. By using the dimple 4 as the grease retaining recess, it is possible to assemble the rotating shaft such as a heat roller regardless of the direction in which the inner ring 2 is assembled. Moreover, a common molded object can be used also when supporting both shafts of a rotating shaft.

  The diameter R of each dimple hole is 0.3 to 2.0 mm. If the diameter R of each dimple hole is less than 0.3 mm, the retention of grease is poor, and if it exceeds 2.0 mm, the amount of grease that does not contribute to lubrication increases.

  The entrance angle α of each dimple hole is preferably 10 to 45 °. If it is less than 10 °, dimple formation is not easily performed, and if it exceeds 45 °, the wedge effect may not be obtained. Moreover, when designing with a diameter of 2.0 mm and an approach angle of 45 °, the recess depth D can be set within 0.7 mm by flattening the bottom.

  Another preferred grease retaining recess is shown in FIG. The grease retaining recess shown in FIG. 4 is a plurality of rows of rectangular grooves 5 showing a half-shape provided on the entire circumference of the outer peripheral surface of the inner ring 2, and the lower side of the half-shape faces the rotation direction of the inner ring 2. It is formed as follows. During the rotation of the inner ring 2, the grease sealed between the inner ring 2 and the outer ring is scraped and moved from the lower side to the upper side in each groove 5. Since the upper side of the letter C in each groove 5 is located at the center in the width direction of the inner ring 2, the grease moves to the center 2a by the above movement. Note that the time when the inner ring 2 rotates is when the inner ring 2 rotates relative to the outer ring 3 and includes the case where the inner ring 2 is fixed and the outer ring 3 rotates.

  As shown in FIG. 5, the grease retaining groove 5 is preferably an inclined groove that becomes deeper from the rectangular side 5a on the rotation direction side toward the opposite side 5b. By making the groove deeper from the rotation direction side toward the opposite side, it becomes easier to scrape the grease when the inner ring 2 is rotated than when there is no such inclination. However, the sliding bearing formed with the grease retaining recess shown in FIG. 4 and FIG. 5 determines the direction to be assembled with respect to the rotational direction of the rotating shaft such as a heat roller, so when supporting both shafts of the rotating shaft, The inner ring 2 in which the grease retaining recess is formed cannot use a common molded body.

  By forming the grease retaining recesses (dimple 4 and groove 5) as described above on the outer peripheral surface of the inner ring 2, a film made of grease can be easily and continuously formed in the center part in the width direction of the bearing (inner ring) that receives the most load. A smooth, low friction torque rotation is obtained. 2, 4, and 5 exemplify the case where the grease holding recess is formed on the outer peripheral surface of the inner ring 2, the grease holding recess can also be formed on the inner peripheral surface of the outer ring 3.

  In the sliding bearing of the present invention, the grease sealed between the inner ring and the outer ring and in the grease retaining recess can be used without particular limitation as long as it is normally used for a bearing. Examples of the base oil constituting the grease include mineral oils such as paraffinic mineral oils and naphthenic mineral oils, hydrocarbon synthetic oils such as polybutene oils, poly-α-olefin oils, alkylbenzene oils, alkylnaphthalene oils, and alicyclic compounds. Or non-hydrocarbon synthetic oils such as natural fats and oils, polyol ester oils, phosphate ester oils, diester oils, polyglycol oils, silicone oils, polyphenyl ether oils, alkyl diphenyl ether oils, and fluorinated oils. These base oils may be used alone or in combination of two or more.

  Further, as the thickener constituting the grease, for example, aluminum soap, lithium soap, sodium soap, composite lithium soap, composite calcium soap, composite aluminum soap and other thickening agents such as diurea compounds and polyurea compounds. Fluorine resin powders such as urea compounds and PTFE resins can be mentioned. These thickeners may be used alone or in combination of two or more.

  Since the slide bearing of the present invention is used to support a fixing roller or the like that operates at a high temperature in an image forming apparatus, the grease also requires heat resistance. Fluorine grease using resin powder as a thickener or urea grease using a urea compound as a thickener is preferably used. Moreover, the grease which mixed these can also be used. In addition, each said grease can be made to contain a well-known additive as needed.

In each example and each comparative example, the synthetic resin and the sintered metal were made of the materials shown below.
(1) Synthetic resin: PPS resin 52% by weight, PTFE resin 33% by weight, graphite 15% by weight
(2) Sintered metal: Fe 60% by weight, Cu 35% by weight, Sn 5% by weight (porosity 20%)
(3) Fluorine grease: DuPont: Krytox GPL205

Examples 1 to 3, Comparative Example 1 and Comparative Example 2
A slide bearing test piece having an inner ring inner diameter of φ25 mm, an outer ring outer diameter of φ37 mm, and a width of 7 mm having a synthetic resin, sintered metal, fluorine grease, and a grease holding recess shown in Table 1 was prepared. This test piece was subjected to the friction and wear test shown below, and the dynamic friction coefficient was measured. The results are also shown in Table 1.

<Friction and wear test>
The dynamic friction coefficient of the sliding bearing 11 was measured using a shaft heating radial tester 10 shown in FIG. The axial heating type radial test machine 10 heats a fixing roller 12 simulating a fixing roller of a fixing device of a copying machine from its inner diameter with a bar heater 13, and controls the surface temperature of the fixing roller 12 to 200 ° C. with a thermocouple 14. . In the test, the sliding bearing 11 was assembled in the housing 15, the fixing roller 12 was inserted into the inner diameter of the inner ring of the sliding bearing 11, pushed up from the lower part of the housing 15 through the ball bearing 17, and a load 16 of 300 N was applied. A turning product (surface roughness Ra 0.5 to 0.7 μm) of aluminum (A5052) was used as the fixing roller 12 material, and the rotation speed of the fixing roller 12 was maintained at 60 rpm through the coupling 18 for 200 hours. The dynamic friction coefficient of the sliding bearing 11 at the initial stage and after 200 hours was calculated by measuring the rotational force of the co-rotating housing 15 with a load cell (not shown). Reference numeral 19 denotes a drive motor.

  As a result of the frictional wear test, the sliding bearing of Example 1 has a high dynamic friction coefficient because of no lubrication, but the dynamic friction coefficient hardly increased even after the 200-hour test. A sliding film of resin is formed on the sliding surface of the sliding bearing, which is considered to be a factor in stabilizing the dynamic friction coefficient. The sliding bearings of Examples 2 and 3 were stable with a low coefficient of dynamic friction even after a 200-hour test from the beginning due to grease lubrication, and almost no wear on the sliding surface of the sliding bearing was observed. On the other hand, in Comparative Example 1 in which the inner ring and the outer ring were formed of synthetic resin and operated without lubrication, the dynamic friction coefficient after the 200-hour test was three times or more of the initial value. Further, black wear powder that seems to be carbonized adhered to the sliding surface. In Comparative Example 2 in which the inner ring and the outer ring were formed of sintered metal and operated with grease lubrication, the dynamic friction coefficient after the 200-hour test was three times the initial value. Moreover, the grease on the sliding surface was almost exhausted.

  The sliding bearing of the present invention is composed of an outer ring and an inner ring, and either the outer ring or the inner ring is made of synthetic resin and the other is made of sintered metal, and the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring are relative to each other. Since the structure is in sliding contact with each other, it has excellent heat dissipation and can be made the same size as a rolling bearing, so that it is compatible and the number of manufacturing processes is reduced, so that the manufacturing cost and the unit price of the product are reduced. Therefore, it can be suitably used as a sliding bearing that supports a heat roller such as a heating roller or a pressure roller of a fixing device in an image forming apparatus such as a copying machine, a printer, or a facsimile machine.

DESCRIPTION OF SYMBOLS 1 Sliding bearing 2 Inner ring 2a Inner ring width direction center part 3 Outer ring 3a Outer ring lower part 3b Outer ring upper part 3c Key 3d Key groove 3e Inner ring incorporation groove 4 Dimple 5 Grease holding groove 5a Rotatable rectangular side 5b 5a Opposite side 10 shaft Heating type high temperature radial tester 11 Sliding bearing 12 Fixing roller 13 Bar heater 14 Thermocouple 15 Housing 16 Load 17 Ball bearing 18 Coupling 19 Drive motor

Claims (19)

  It is composed of an outer ring and an inner ring, and either the outer ring or the inner ring is made of synthetic resin and the other is made of sintered metal, and the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring are relatively in sliding contact with each other. A sliding bearing characterized by that.   2. The sliding bearing is a bearing that supports a heat roller, and the heat roller is a heater built in the heat roller or a roller heated by heat transfer from another member. The described plain bearing.   The sliding bearing according to claim 2, wherein the heat roller is a fixing roller or a pressure roller in the image forming apparatus.   4. The plain bearing according to claim 1, wherein the outer peripheral surface of the inner ring is a convex curved surface, and the inner peripheral surface of the outer ring is a concave curved surface corresponding to the convex curved surface.   The outer ring has a shape divided into two in the radial direction, and the inner ring is sandwiched between the two divided outer rings, and the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring are relatively in sliding contact with each other. The sliding bearing according to any one of claims 1 to 4, wherein the sliding bearing is incorporated as described above.   The outer ring is formed with an inner ring incorporating groove at two opposing locations on the inner peripheral surface thereof, and the inner ring incorporating groove is formed to open at least one end surface of the outer ring. 5. The plain bearing according to claim 4, wherein the plain bearing is incorporated in the outer ring through an inner ring incorporating groove.   The inner ring is inserted into the outer ring through the inner ring incorporating groove in a state in which the axis of the inner ring is shifted from the axis of the outer ring, and then the inner ring and the outer ring are rotated relative to each other to rotate the shaft of the inner ring. The plain bearing according to claim 6, wherein the bearing is incorporated in the outer ring by aligning the center with the axis of the outer ring.   The grease is sealed between the inner ring and the outer ring, and a grease holding recess for holding the grease is formed on an outer peripheral surface of the inner ring. The plain bearing described in the item.   9. The sliding bearing according to claim 8, wherein the depth of the grease retaining recess is 0.03 to 0.7 mm at the deepest portion.   10. The slip according to claim 8, wherein the grease retaining recess is an inverted conical dimple having a diameter of 0.3 to 2.0 mm provided on the entire circumference of the outer peripheral surface of the inner ring. bearing.   The sliding bearing according to claim 10, wherein the dimple has an opening angle of 10 to 45 degrees.   The grease retaining recess is a plurality of rows of rectangular grooves having a C shape provided on the entire outer periphery of the inner ring, and is formed so that the lower side of the C shape faces the rotation direction of the inner ring. The sliding bearing according to claim 8 or 9, wherein the sliding bearing is provided.   13. The plain bearing according to claim 12, wherein the plurality of rectangular grooves are inclined grooves whose grooves deepen from the rectangular side on the rotation direction side toward the opposite side.   The sliding bearing according to any one of claims 1 to 13, wherein the synthetic resin is a resin composition containing a solid lubricant.   The plain bearing according to claim 14, wherein the base resin of the resin composition is a polyphenylene sulfide resin.   The sliding bearing according to any one of claims 1 to 15, wherein the sintered metal contains at least one selected from copper and iron as a main component.   The plain bearing according to any one of claims 8 to 16, wherein the grease is at least one selected from fluorine grease and urea grease.   The plain bearing according to any one of claims 1 to 17, wherein the inner ring is made of sintered metal, and the outer ring is made of synthetic resin.   The plain bearing according to any one of claims 1 to 17, wherein the inner ring is made of a synthetic resin, and the outer ring is made of a sintered metal.

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