JP2011074979A - Slide bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a slide bearing of low cost and a simple structure which achieves effective use of filled grease and keeps friction torque low. <P>SOLUTION: The slide bearing 1 is a bearing supporting a rotor rotating in only one direction. Grease is filled between the inner ring 2 and the outer ring 3. A grease retention groove 4 retaining grease is formed on an outer circumference surface of the inner ring 2. The grease retention groove 4 is a plurality of truncated chevron shaped two row rectangle groves provided on a whole circumference of an outer circumference of the inner ring 2. The groove is formed in such a manner that a lower side of the truncated chevron shape is oriented to a rotation direction of the inner ring 2 and is an inclined groove of which depth becomes deeper toward an opposite edge from a rectangle edge at the rotation direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sliding bearing used for supporting a heating roller of a fixing device in an image recording apparatus such as a copying machine, a printer, and a facsimile machine.

  In general, an image recording apparatus attaches toner to an electrostatic latent image formed by an optical device, transfers the toner image to a copy sheet, and further fixes it. 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), and the surface is finished by turning or polishing, and the surface has a highly non-adhesive resin such as fluororesin. Is coated or coated. The surface temperature of the fixing roller is heated to about 180 to 250 ° C. by a heater.

  The pressure roller that rotates by pressing the copy paper against the fixing roller is made of an iron material or a soft material coated with silicon rubber or the like, and is heated to about 70 to 150 ° C. by heat transfer from the heating roller. The

  In particular, a fixing 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 between the rolling bearing and the shaft portion of the fixing roller. In order to prevent heat from escaping from the rolling bearings at both ends during heating of the fixing roller and non-uniform temperature distribution along the axial direction of the fixing roller, and to prevent high temperature deterioration of the bearing, synthetic resin, etc. The insulation sleeve which consists of is interposed.

  In addition, as a support bearing for the fixing roller, there is a type using a resin sliding bearing, and a synthetic resin such as polyphenylene sulfide (hereinafter abbreviated as PPS) resin, polyamide resin, polyamideimide resin, polyimide resin, or polyether ether ketone resin. Formed from. 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).

Japanese Patent Laid-Open No. 5-117678

  However, the deep groove ball bearing of the fixing roller bearing of the fixing device in the image recording 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.

  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 sliding surface roughness of the fixing roller is large, there is a problem that the friction torque becomes larger, and at the same time, the wear becomes larger, so that 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 to cope with such problems, and provides a sliding bearing that has a low-cost, simple structure, can effectively use the enclosed grease, and can keep the friction torque low. Objective.

  The sliding bearing of the present invention is a sliding bearing comprising a combination of an inner ring and an outer ring, in which grease is sealed between the inner ring and the outer ring, and supports a rotating body that rotates only in one direction. A grease holding groove for holding the grease is formed on the outer peripheral surface, and the grease holding groove is a plurality of rectangular grooves of two rows indicating a C shape provided on the entire outer periphery of the inner ring. And the lower side of the C-shape is formed so as to face the rotation direction of the inner ring.

  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 depth of the grease retaining groove is 0.01 to 0.5 mm at the deepest portion in each of the plurality of grooves.

  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 that is divided into two in the radial direction, and the inner ring is sandwiched between the outer rings that are 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 with each other. It is characterized by that.

  The inner ring and the outer ring are synthetic resin moldings. The synthetic resin is a PPS resin.

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

  The rotating body is a fixing roller or a pressure roller for fixing a toner image in an image recording apparatus to a sheet.

  Since the sliding bearing of the present invention comprises a combination of an inner ring and an outer ring, grease is sealed between the inner ring and the outer ring, and a grease holding groove for holding grease is formed on the outer peripheral surface of the inner ring. Grease is held in the grease holding groove, and the friction torque can be kept low. Moreover, since it is a simple structure composed of an inner ring and an outer ring, it can be manufactured at a lower cost than a rolling bearing. As a result, in comparison between a deep groove ball bearing with low friction torque but high manufacturing cost and a plastic sliding bearing with low friction torque but high friction torque (no grease retaining groove), the balance between friction torque and manufacturing cost Therefore, it can be located between the two.

  The sliding bearing is a bearing that supports a rotating body that rotates in only one direction, and the grease retaining groove is a two-row strip type that indicates a half-shape provided on the entire outer periphery of the inner ring. It is a plurality of grooves, and the lower side of the letter C is formed so that the lower side of the groove faces the direction of rotation of the inner ring. Always raked into the department. 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. Further, since the depth of the grease retaining groove is 0.01 to 0.5 mm at the deepest portion in each of the plurality of grooves, the grease can be retained in the groove sufficiently and without waste.

  Moreover, 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, alignment can be imparted.

  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 with each other. Therefore, even if 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 can be incorporated. Further, the inner ring can be sandwiched and assembled after sufficiently applying grease to the grease retaining groove on the outer peripheral surface of the inner ring.

  Further, since the inner ring and the outer ring are molded articles of synthetic resin such as PPS resin, they can be used for supporting the fixing roller and the pressure roller in the image recording apparatus without interposing a heat insulating sleeve, and can be injection molded. Can be produced at low cost.

Further, since the grease to be enclosed is at least one selected from fluorine grease and urea grease, excellent heat resistance is exhibited.

It is a perspective view of the sliding bearing of the present invention and a perspective view showing a state before the inner and outer rings are combined. It is a perspective view which shows the inner ring | wheel (overall view) of the slide bearing in FIG. It is a perspective view which shows the lower half of the outer ring | wheel of the slide bearing in FIG. FIG. 3 is a partially enlarged perspective view of a grease holding groove in FIG. 2. It is the fragmentary sectional view which cut | disconnected the sliding bearing in FIG. 1 to the axial direction. It is a schematic diagram of a shaft heating type high temperature radial testing machine. It is a bar graph which shows a rotational torque comparison test result.

  An embodiment of the slide bearing of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a sliding bearing of the present invention and a perspective view showing a state before the inner and outer rings are combined, FIG. 2 is a perspective view showing an inner ring of the sliding bearing of the present invention, and FIG. It is a perspective view which shows the lower half of the outer ring | wheel of a bearing. As shown in FIG. 1, the sliding bearing 1 of the present invention comprises a combination of an inner ring 2 (overall view is FIG. 2) and an outer ring 3, and a grease holding groove 4 that holds grease is formed on the outer peripheral surface of the inner ring 2. Has been. Grease (not shown) is sealed between the inner ring 2 and the outer ring 3. 1 and 2, the direction indicated by the white arrow is the rotation direction of the inner ring 2.

  The sliding bearing 1 supports a rotating body such as a fixing roller or a pressure roller for fixing a toner image in the image recording apparatus on a sheet at the inner diameter of the inner ring 2. When the rotating body has a shaft, the shaft is supported by the inner ring 2. The rotating bodies such as the fixing roller and the pressure roller of the image recording apparatus rotate only in one direction, and the rotating direction of the inner ring 2 is the rotating direction of the rotating body.

  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. At the time of assembly, it is preferable to incorporate the inner ring 2 into which the grease is sufficiently applied (enclosed) in the grease retaining groove 4 in advance to the outer ring 3.

  As shown in FIGS. 1 and 3, a key 3c and a key groove 3d are provided at one of the split surfaces divided into two in the radial direction of the outer ring lower portion 3a at the left and right target positions. Corresponding key grooves and keys 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.

  The grease retaining groove 4 will be described in detail based on FIG. 2 and FIG. 4 is a partially enlarged perspective view of FIG. As shown in FIGS. 2 and 4, the grease retaining groove 4 is a plurality of two rows of rectangular grooves having a C shape provided on the entire outer periphery of the inner ring 2, and the lower side of the C is the inner ring. It is formed so as to face the direction of rotation 2. 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 4. Since the upper side of the letter C in each groove 4 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. 4, the grease retaining groove 4 is preferably an inclined groove that becomes deeper from the rectangular side 4a on the rotation direction side toward the opposite side 4b. 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.

  The depth of the grease retaining groove 4 is preferably 0.01 to 0.5 mm at the deepest portion in each of the plurality of grooves. The depth of the groove is the distance from the outer peripheral surface (front surface) of the inner ring 2 to the groove bottom, and when the groove is an inclined groove, the depth on the deep side (opposing side 4b side) is within the above range. It is preferable that If the groove depth is less than 0.01 mm, the groove is too shallow to hold sufficient grease for lubrication. On the other hand, if the groove depth exceeds 0.5 mm, the groove is too deep and grease accumulates at the groove bottom, increasing the amount of grease that does not contribute to lubrication.

  By forming the grease retaining groove 4 as described above on the outer peripheral surface of the inner ring 2, a film made of grease is easily and continuously formed in the center portion in the width direction of the bearing (inner ring) that receives the most load. In addition, rotation with low friction torque can be obtained. Note that the above grease retaining grooves can also be formed on the inner peripheral surface of the outer ring.

  FIG. 5 shows a partial cross-sectional view of the plain bearing of FIG. 1 cut in the axial direction. As shown in FIG. 5, the outer peripheral surface of the inner ring 2 is a convex curved surface, and the inner peripheral surface of the outer ring 3 is a concave curved surface corresponding to the convex curved surface. Moreover, it is preferable that the outer peripheral surface of the inner ring 2 having the convex curved surface is flat only in the central portion in the width direction of the inner ring 2 in the cross section in the axial direction. Even if the inner ring 2 and the outer ring 3 have such a shape, since the outer ring 3 has a split shape, the inner ring 2 can be easily incorporated into the outer ring 3 (see FIG. 1). Further, by using this shape, alignment can be imparted to the sliding bearing 1. In addition, the uneven | corrugated relationship in the outer peripheral surface of an inner ring | wheel and the inner peripheral surface of an outer ring | wheel may be a relationship opposite to this embodiment.

  In the sliding bearing of the present invention, the outer ring and the inner ring are preferably formed of a synthetic resin. The type of the synthetic resin is not particularly limited, but it is necessary that the synthetic resin has characteristics that meet at least the usage conditions (heat resistance, mechanical strength, etc.) of the 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. In addition, about an outer ring | wheel, a structural material is used and a metal cutting processed product and a sintered metal body may be sufficient.

  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 recording apparatus.

  Moreover, glass fiber, carbon fiber, and various mineral fibers (whiskers) may be blended with 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 resin, graphite, and molybdenum disulfide.

  In the sliding bearing of the present invention, the grease sealed between the inner ring and the outer ring and in the grease retaining groove can be used without particular limitation as long as it is normally used for the 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. Examples thereof include fluorine resin powders such as urea compounds and polytetrafluoroethylene resins. These thickeners may be used alone or in combination of two or more.

  When the sliding bearing of the present invention is used for supporting a fixing roller or the like that operates at a high temperature in an image recording apparatus, heat resistance is also required for the grease. It is preferable to use a fluorine grease containing a fluororesin powder as a thickener or a urea grease containing a urea compound as a thickener. 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.

Example 1
The whole inner ring of FIG. 2 was integrally molded by injection molding with a mold using a slidable resin material made of PPS resin blended with a fluororesin. As the synthetic resin material, NTN BEAREE AS5054 (PPS resin composition) was used. The outer ring was formed by injection molding of a plurality of outer rings shown in FIG. 1 using NTN BEAREE AS5040 material in which PPS resin was reinforced with glass fiber as a synthetic resin material. The dimensions of the obtained sliding bearing are inner ring inner diameter φ30 mm, outer ring outer diameter φ37 mm (flange outer diameter φ39 mm), and total width 7 mm (flange width 1 mm). As grease, 5 g of fluorine grease (manufactured by DuPont: Krytox GPL205) was uniformly applied to the grease retaining groove of the inner ring. After applying the grease, the inner ring was incorporated into the outer ring to obtain a bearing test piece 11. The obtained bearing test piece 11 was subjected to the rotational torque test shown below to determine the rotational torque. The results are shown in FIG. 7 and the comprehensive judgment considering the manufacturing cost is also shown in Table 1.

<Rotational torque test>
The rotational torque of the bearing test piece 11 was measured using the shaft heating type high temperature radial tester 10 shown in FIG. A shaft heating type high-temperature radial testing machine 10 heats a fixing roller 12 simulating a fixing roller of a fixing device of a copying machine from its inner diameter by a cartridge heater 13, and a thermocouple 14 brings the surface temperature of the fixing roller 12 to a predetermined temperature. It is something to control. In the test, the bearing test piece 11 is assembled in the housing 15, and the fixing roller 12 is inserted into the inner ring inner diameter of the bearing test piece 11. From the lower part of the housing 15, it was pushed up via a ball bearing 17 and a load 16 of 300 N was applied. Aluminum (A5052) turned product (surface roughness Ra 0.5-0.7 μm) is used for the fixing roller 12 material, the rotation speed of the fixing roller 12 is 73 rpm, the surface temperature of the fixing roller 12 is 200 ° C., and the test time is 50 hours. For lubrication, the bearing test piece 11 was tested dry. In this state, the fixing roller 12 is rotated by the drive motor 19 through the coupling 18, and the rotational torque of the bearing test piece 11 is measured by measuring the rotational force of the co-rotating housing 15 with a load cell (not shown). Calculated.

<Manufacturing cost>
Manufacturing costs (calculation costs) were quantified by relative evaluation when Example 1 was set to 100 and recorded respectively.

<Comprehensive judgment>
Considering the results of the rotational torque test in FIG. 7 and the manufacturing cost in Table 1, when there is no inferior rotational torque and calculated cost, it is comprehensively determined that the balance between the two is good, and a “◯” mark is given. If any one of the rotational torque and the calculated cost is inferior, the overall balance is judged to be poor, and “x” marks are recorded respectively.

Comparative Example 1
NTN ball bearing: 6706ZZ with retaining ring (inner ring inner diameter, outer ring outer diameter and width are the same dimensions as the sliding bearing used in Example 1) Evaluation was performed. The results are shown in FIG.

Comparative Example 2
A sliding bearing (same dimension as the sliding bearing used in Example 1) obtained by injection molding a sliding resin material comprising a PPS resin-based composition containing 30% by weight of a fluororesin was used as a bearing test piece. Except for this, the same tests and evaluations as in Example 1 were performed. The results are shown in FIG.

  As a result of the torque comparison test in FIG. 7, the sliding bearing of Example 1 has a rotational torque increase of about 13% compared to the ball bearing of Comparative Example 1, and the rotational torque is reduced by about 17% compared to the resin sliding bearing of Comparative Example 2. Was confirmed. As is apparent from the results in Table 1, it can be seen that the sliding bearing of Example 1 is generally superior to the resin sliding bearing and the ball bearing without the grease retaining groove.

  The sliding bearing according to the present invention comprises a combination of an inner ring and an outer ring, wherein grease is sealed between the inner ring and the outer ring, and a grease retaining groove having a predetermined shape for retaining the grease is formed on the outer peripheral surface of the inner ring. Therefore, the sliding bearing has a good balance between the friction torque and the manufacturing cost, and can be suitably used as a sliding bearing used for a heating roller of a fixing device in an image recording apparatus such as a copying machine, a printer, or a facsimile.

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 4 Grease holding groove 4a Rotational direction side rectangular side 4b 4a Opposite side 10 Axial heating high temperature radial tester DESCRIPTION OF SYMBOLS 11 Bearing test piece 12 Fixing roller 13 Cartridge heater 14 Thermocouple 15 Housing 16 Load 17 Ball bearing 18 Coupling 19 Drive motor

Claims (9)

A sliding bearing comprising a combination of an inner ring and an outer ring, in which grease is enclosed between the inner ring and the outer ring, and supporting a rotating body that rotates only in one direction,
A grease holding groove for holding the grease is formed on the outer peripheral surface of the inner ring, and the grease holding groove is a plurality of two rows of rectangular shapes indicating a C shape provided on the entire outer periphery of the inner ring. The slide bearing is characterized in that the lower side of the C-shape is formed so as to face the rotation direction of the inner ring.   2. The plain bearing according to claim 1, 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.   3. The plain bearing according to claim 1, wherein a depth of the grease retaining groove is 0.01 to 0.5 mm at a deepest portion in each of the plurality of grooves.   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 that is divided into two in the radial direction, and the inner ring is sandwiched between the outer rings that are 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 with each other. The plain bearing according to any one of claims 1 to 4, wherein the plain bearing is provided.   The sliding bearing according to any one of claims 1 to 5, wherein the inner ring and the outer ring are synthetic resin moldings.   The sliding bearing according to claim 6, wherein the synthetic resin is polyphenylene sulfide resin.   The sliding bearing according to any one of claims 1 to 7, wherein the grease is at least one selected from fluorine grease and urea grease.   9. The plain bearing according to claim 1, wherein the rotating body is a fixing roller or a pressure roller that fixes a toner image in an image recording apparatus to a sheet.

Images