JPH08240220A - Bearing structure for high temperature and bearing structure of heating fixer - Google Patents

Abstract

PURPOSE: To restrain stress caused by temperature variation of an sliding bearing and restrain the wear of the sliding bearing and a fixing roller caused by so-called screw action. CONSTITUTION: This bearing structure is applied to a heating fixer for supporting rotatably a fixing roller 1 having a heater 2 built therein at the end with an sliding bearing 3. A bushing 8 made of a heat resisting material is provided between the sliding bearing 3 and fixing roller 1. The bushing 8 is moved into sliding contact with the sliding bearing 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing structure for high temperature used in various industrial equipment, and more specifically, a copying machine,
The present invention relates to a bearing structure of a heat fixing device in an electrophotographic device such as a laser beam printer.

[0002]

2. Description of the Related Art Generally, an electrophotographic apparatus is one in which toner is attached to an electrostatic latent image formed by an optical device, the toner image is transferred to a copy sheet, and further fixed. In the fixing step, The toner image is heat-fused on the copy paper by a fixing roller with a built-in heater. 5 to 7
Are examples of various conventional bearing structures. In each case, the fixing roller 51 has a linear heater 52 built in at the axial center thereof, and is rotatably supported at the end by bearings 53 to 55. 56 shows a housing.

In the example of FIG. 5, a ball bearing is used for the bearing 53, and a heat insulating bush 57 is fixed to a small diameter journal portion 51a protruding from the end portion of the fixing roller 51, and the bearing 53 is provided on the outer periphery thereof. Is provided. The heat insulating bush 57 is
The heat dissipation from the bearing 53 of the fixing roller 51 is prevented, the heat loss is reduced, and the fixing property is improved. As an example of adopting a bearing structure as shown in the figure, for example, Japanese Patent Laid-Open No. 6-6
There is one disclosed in Japanese Patent No. 7558. The example of FIG. 6 is an example in which a resin slide bearing fixed to the housing 56 is used as the bearing 54, and the slide bearing 54 is the fixing roller 51.
It is rotatably in contact with the outer diameter surface of. The fixing roller 51 is
The bearing 54 has substantially the same diameter over the portion supported by the bearing.

In the example of FIG. 7, a cylindrical slide bearing is used as the bearing 55, and the bearing holding member 5 fixed to the housing 56.
A heat insulating bush 59 is interposed between the bearing 8 and the bearing 55. The heat insulating bush 59 is the bearing holding member 58.
The bearing 55 is also fixed to the inner diameter surface of the heat insulating bush 59 in a pressed fit state. Rotational support by sliding contact is performed between the inner surface of the bearing 55 and the outer diameter surface of the fixing roller 51. In some documents, the bearing holding member 58 is referred to as a bearing, and the sliding bearing 55 is simply described as a tubular member. However, regardless of the name of the part, the bearing 55 performs rotational support by sliding contact. As a conventional example of such a bearing type, for example, Japanese Utility Model Publication No. 61-4
There is one disclosed in Japanese Patent Publication No. 920.

[0005]

In the example of FIG. 5 and other general examples, since the rolling bearing in which expensive high temperature grease such as heat resistant fluorine grease is filled is used as the bearing 53, the fixing is performed. There are problems that the cost of the parts becomes relatively high and that it is difficult to reduce the size. Therefore, the use of slide bearings is desired for cost reduction. The heat resistance of grease is determined by the base oil and the thickener. Examples of the base oil of the heat resistant grease include silicone oil, fluorosilicone oil, perfluoroalkyl ether oil, perfluoropolyether oil, phenyl ether oil, and the like.
As the thickener, urea powder, boron nitride powder,
Fluorine-based resin powders such as tetrafluoroethylene resin powder, lithium complex, and the like, and various high-temperature heat-resistant greases in which these are appropriately blended are available. Examples thereof include complex greases such as calcium complex grease, aluminum complex grease and lithium complex grease, fluorine greases such as PTFE grease and PTFE-PFAE grease, and silicone greases. These are about 200-250 ° C, and the maximum instantaneous temperature is about 300 ° C.
Some can be used at a high temperature of about ℃, but the viscosity is high and the consistency is hard because of the blending amount of base oil and thickener to enhance heat resistance. Therefore, such a rolling bearing filled with a large amount of grease has a relatively high rotational torque because the viscosity of the grease is high and the consistency is hard. In addition, depending on the severe operating temperature conditions, the grease may be slightly hardened or oxidized,
Depending on the specifications, there were times when grease had to be added and lubricated. Further, both the base oil and the thickener are very expensive, resulting in a high temperature bearing which is expensive and has a high rotational torque and may require refueling work, and it is required to improve the bearing.

In the example of FIG. 6, since a sliding bearing is used for the bearing 54, the cost is low, but there is a problem that it is difficult to improve the durability. That is, since the resin bearing 54 is in direct contact with the fixing roller 51, stress in the thrust direction and the circumferential direction of the fixing roller 51 is generated in the bearing 54 due to temperature fluctuations. In recent years, the temperature of the fixing roller 51 has been raised with the quick start and the improvement of the material of the toner, and therefore the problem of the stress of the slide bearing 54 has become serious. Further, the fixing roller 51 is made of a soft metal material such as aluminum by turning. However, due to the spiral groove-like fine irregularities formed on the surface by the turning, a screw action is generated and a thrust is applied in one direction. Acts to promote wear of the slide bearing 54 and the fixing roller 51. For these reasons, it is difficult to improve the durability of the slide bearing 54 and the fixing roller 51.

In the example of FIG. 7, the heat loss is reduced by the presence of the heat insulating bush 59 and the fixing property is improved, but the sliding bearing 55 is in direct sliding contact with the surface of the fixing roller 51 as in the example of FIG. Therefore, it is difficult to improve wear resistance as in the example of FIG. Further, since the heat insulating bush 59 is arranged on the outer circumference of the slide bearing 55, the stress of the slide bearing 55 due to the temperature fluctuation of the fixing roller 51 occurs as in the case where the heat insulating bush 59 is not provided. As other conventional examples, various types using a heat insulating bush as in the example of FIG. 7 have been proposed.
Since both of them are configured to make sliding contact with the surface of the fixing roller, it is difficult to improve durability due to stress caused by wear and temperature fluctuations.

The present invention solves such a problem, and can suppress the stress due to the temperature fluctuation of the sliding bearing and the wear due to the so-called screw action to improve the durability of the sliding bearing and the fixing roller. It is an object of the present invention to provide a bearing structure for a heat fixing device that can be used.

[0009]

The bearing structure of the present invention comprises:
In a high temperature bearing structure in which a shaft is rotatably supported by a slide bearing, a bush made of a heat resistant material is interposed between the slide bearing and the shaft so as to rotatably contact the slide bearing. It is characterized by This bearing structure is applied, for example, to a bearing structure of a heat fixing device in which a fixing roller having a built-in heater is rotatably supported by a slide bearing at its end. The bush may be made of a material having higher heat resistance than the plain bearing. Also,
The bush may be made of ceramics, and the bush may be made of a resin material having heat resistance higher than the shaft surface temperature.

According to this structure, the fixing roller is in sliding contact with the sliding bearing via the bush of the heat-resistant resin material provided on the outer circumference. Therefore, even if the fixing roller is made of a turned aluminum product, the thread action due to the thread groove-like irregularities on the surface does not occur, and the sliding bearing and the fixing roller are not worn by this screw action. In addition, since the bush made of a heat-resistant material is interposed, there is also an adiabatic effect of heat conduction from the fixing roller to the sliding bearing, and the stress of the sliding bearing due to temperature fluctuation is reduced. These improve the durability of the slide bearing and the fixing roller.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. FIG. 1A is a cutaway front view of the fixing device. The fixing roller 1 includes a linear or rod-shaped heater 2
Is made of a soft metal and has a cylindrical shape with the same diameter over its entire length. The material of the fixing roller 1 is, for example, aluminum or aluminum alloy (A5056, A6063, etc.), and the surface is finished by turning, polishing, or the like. The fixing roller 1 is rotatably supported by the housing 4 at both ends via slide bearings 3 and 3, and a gear 5 for receiving rotational power is provided on one end side of the slide roller 3 at one end. A pressure roller 6 is provided in contact with the fixing roller 1 in parallel with the fixing roller 1, and is rotatably supported by the housing 4 via bearings 7, 7 at both ends. The copy paper is fed between the fixing roller 1 that is rotationally driven and the pressure roller 6 that is driven, and the toner image is fixed by heat fusion by the fixing roller 1.

A cylindrical bush 8 made of a heat-resistant resin material is interposed between the slide bearings 3, 3 at both ends and the outer diameter surface of the fixing roller 1, as shown in an enlarged view in FIG. 1 (B). There is. The bush 8 is attached to the outer periphery of the fixing roller 1 in a fitted state, is prevented from rotating with respect to the fixing roller 1 via a key 8a which is a rotation preventing means, and has an outer diameter surface which is an inner diameter surface of the slide bearing 3. Sliding contact with the bearing surface 3a. Key 8a
Is integrally projected on the inner diameter surface of the bush 8 along the axial direction, and engages with the key groove 1a provided on the outer diameter surface of the end portion of the fixing roller 1. Further, the bush 8 has a flange 8 b on the outer periphery at the center side end of the fixing roller 1, and is engaged with the inner side surface of the slide bearing 3. A retaining ring 9 is fitted in a retaining ring groove 10 of the fixing roller 1 in contact with the end face of the bush 8 on the side of the flange 8b, and the retaining ring 9 and the slide bearing 3 form the bush 8 at both ends of the fixing roller 1. The axial movement of the bush 8 and the fixing roller 1 is constrained by the flange 8b being sandwiched. The key 8a is provided integrally with the bush 8 instead of
It may be an independent member and may be engaged with a key groove formed in both the bush 8 and the fixing roller 1.

The plain bearing 3 is a resin ring-shaped member having an outer diameter surface formed into a stepped cylindrical surface, and is a flat surface which is a rotation preventing portion at a part of the large diameter portion of the outer diameter surface in the circumferential direction. The portion 3b (FIG. 2) is formed. The plain bearing 3 is mounted by being fitted in a bearing mounting hole provided in the housing 4, and is engaged with the flat portion in the bearing mounting hole of the housing 4 by the flat portion 3b to be prevented from rotating.

A material example will be described. The bush 8 is made of a polyamide-imide type, a polyimide type, a polyether imide type, a polyether ketone type, a polyether ether ketone type, a polyarylene sulfide type, etc., and is reinforced with various fillers. The super heat resistant resin having the above can be used. For the sliding bearing 3, a resin material having excellent sliding characteristics such as polyphenylene sulfide resin (hereinafter referred to as “PPS resin”) or polyamide is used. Of these, the following materials will give a bearing with excellent heat resistance and wear resistance. That is, the plain bearing 3 is made of PP
S-based resin, 5-40% by weight of tetrafluoroethylene resin,
Molten fluororesin 3 to 20% by weight and one or more heat-resistant synthetic resin 5 selected from the group consisting of aromatic polyester resins, polyimide resins, polyetherketone resins, aromatic polyamide resins and phenol resins. Three
It is preferably composed of a resin composition containing 0% by weight as an essential component. Further, further, an inorganic or organic filler of carbon such as glass fiber, carbon fiber, graphite or the like is added in an amount of about 3 to 5 parts by weight in an amount of about 3 to 18 parts by weight.
Each may be added for each part by weight. If it is less than about 3 parts by weight, the reinforcing effect cannot be expected, and if it is more than about 18 parts by weight, it is expected that the mating material will be damaged. By mixing such a filler with a resin material, the deflection temperature under load can be adjusted to about 30
It can be improved up to 100 ° C or higher.

As the physical properties of the fibrous reinforcing material or powdery additive of the filler, the specific resistance is about 10 ^-2 Ω · cm.
It is preferable that the conductive material or the semi-conductive material has a specific resistance of about 10 ⁻⁴ Ω · cm or less, and the conductive material or the semi-conductive material has a specific resistance of about 10 ⁻⁴ Ω · cm or less. 3 to 15% by weight may be separately mixed.

Examples of such a conductive substance having sliding properties include, for example, ferrous metals, non-ferrous metals,
Inorganic materials and the like are listed, and specific examples include the following. The specific resistance values are shown in parentheses.

Iron (about 9.71 × 10 ⁻⁶ Ω · cm), iron oxide (about 4 × 10 ⁻³ Ω · cm), aluminum (about 2.65 ×)
10 ^-6 Ω · cm), carbon (approximately 4 × 10 ^{-5 to} 7 × 10 ^-5
Ω / cm).

Of these, aluminum fibers, carbon fibers and the like are preferable because they have the properties of conductivity and semi-conductivity while also playing the role of reinforcing fibers. Further, the slidability may be emphasized by selecting the above-mentioned substance in the powder form instead of the fibrous form.

By filling such a conductive material in an amount within the above range, it is possible to obtain a bearing structure having conductivity in addition to heat resistance and heat insulation, so that development of an electrophotographic apparatus is possible. It is possible to remove static electricity due to the influence of electric charges from the charging device and static electricity generated from each operating part through each ground member, such as a device or a fixing device. It is considered that this makes it possible to prevent a situation in which foreign matter such as dust as described above adheres to the sliding portion of the bearing due to static electricity and causes abnormal wear.

With regard to such a bearing structure, if at least the bearings and bushes that slide adjacently are made of such a conductive material or a semiconductive material, static electricity is transmitted through each bearing and finally conductive such as metal. Since it is possible to remove static electricity by escaping from the flexible housing, each grounding member can be omitted, and for example, the fixing device and the developing device of the electrostatic copying machine can be made smaller and lighter, and the cost can be reduced. Also leads to

The volume resistivity of such a conductive, semi-conductive or micro-conductive plain bearing / bush is 10 ¹⁷ Ω · cm or less, preferably 1 to 10 ⁸ Ω · cm or less. It need not be a value. The preferred measuring method is ASTM D-257, but is not particularly limited.

According to the bearing structure having this structure, the fixing roller 1 makes sliding contact with the slide bearing 3 via the bush 8 made of a heat-resistant resin material provided on the outer periphery. Therefore, the fixing roller 1
Even if it is made of a turned product such as an aluminum alloy, the thread action due to the thread groove-shaped irregularities on the surface does not occur, and the sliding bearing 3 and the fixing roller 1 are not worn due to this thread action. Because the bush is manufactured by injection molding, the outer periphery of the bush becomes the transfer surface of the cavity surface of the mold. This is because a smooth surface is formed on the bush surface by finishing the finish of the cavity surface with a comma and wrap. In addition, since the bush 8 made of a heat-resistant resin material is interposed, there is also an adiabatic effect of heat conduction from the fixing roller 1 to the slide bearing 3, and the slide bearing 3 due to temperature fluctuations.
Stress is relieved. As a result, the durability of the slide bearing 3 and the fixing roller 1 is improved. Further, due to the heat insulating property of the bush 8, heat dissipation from the fixing roller 1 through the sliding bearing 3 and the housing 4 is suppressed, heat loss is prevented, and the fixing property is improved.

An experimental example will be described. In the bearing structure of the embodiment of FIG. 1, the following materials were used and a comparative example of the structure of FIG. 6 was tested for wear. The plain bearing 3 is made of PPS.
Molding was performed using a resin material to obtain a test piece. For the bush 8, a polyamide-imide resin-based material (PAI (Amorco's Torlon 4203)) and a polyimide resin-based material (PI (Mitsui Toatsu Kagaku's NEW-TP1)) were used. A conductive substance and a semiconductive substance are mixed in these. The bushing material may be a heat-resistant synthetic resin of each of the compositions of the plain bearing material, or the PPS resin is the main component, and each of the synthetic resins is the main component. It may be a composition. The experiment was conducted by a high temperature radial test. A high temperature Laal tester manufactured by NTN Precision Resins Co., Ltd. was used as the tester. In this case, the aluminum alloy material (A606 whose surface temperature was controlled to 220 ° C) was used.
3, the surface roughness of 3.2S) as a mating member,
Bushing (inner diameter 2
4.9, outer diameter 35.0, width 10.0 (mm)) were press-fitted. A sliding bearing (inner diameter 35.3, outer diameter 45.0, width 6 (mm)) rotatably fitted around the outer circumference of this bush was pressed against the peripheral surface of the mating material with a pressure of 3.5 kgf / cm ² , A 100-hour test was performed with 20 seconds of operation and 1 second of intermittent operation. The results are shown below.

[0024]

As is clear from this table, Examples 1 and 2
Almost no wear was observed on either the slide bearing or the fixing roller. In the comparative example, the fixing roller had a screw action and abrasion was observed. In Table 1, ◯ marks and X marks indicate that no wear exceeding a predetermined level was observed.
And the case where it is recognized. Plain bearing 3 and bush 8
The combination with and is not particularly limited, but if possible, it is preferable to use a resin having a different material as a main component and a slightly different hardness, and if the materials are the same, stick-slip or depending on the surface condition of the sliding surface, It is expected that some abrasion will occur due to adhesion. Also, the plain bearings 3 with different main components
And the bush 8 are combined, the fixing roller 1 has a surface temperature of about 150 ° C. to about 230 ° C. or higher, and the higher one has an instantaneous maximum temperature of about 300 ° C. or higher. Since high temperature heat resistance is required, it is preferable to select a material having higher heat resistance than the slide bearing 3. The ring member made of heat-resistant resin exhibits heat insulating characteristics of about 30 ° C. to 60 ° C. at the above-mentioned temperature, although it depends on specifications and conditions. , The sliding part is lower than the roller surface temperature and is not severe. The heat resistance and hardness of the resin molded product depends on the compounding amount of each resin, the addition amount of the filler, etc.
Although it is difficult to judge in a general way, the thermal properties and hardness of each standard heat-resistant resin are as follows. still,
The respective values in parentheses are listed from the front in the order of glass transition temperature, melting point, deflection temperature under load, Rockwell hardness (partial Shore hardness), linear expansion coefficient, and volume resistivity. In addition, those for which clear measurement points are difficult to measure, those for which it is unknown, and some items of the thermosetting resin are expressed as −. An abbreviation is added to each resin.

Phenolic resin (PF) (-,-, 74-14
4 ℃, M93 ~ 128, 1.1 ~ 6.8 × 10 ^-5 / ℃ 10 ¹² ~ 1
0 ¹⁸ Ω · cm) Polyimide resin (PI) (-,-, 350-360 ° C, M11
8, 0.8 to 6.6 x 10 ^-5 / ° C, 10 ¹⁶ to 10 ¹⁸ Ω · cm Thermoplastic polyimide resin (PI) (250 ℃, 388 ℃, 23
8 to 260 ° C, E52 to 99, 0.4 to 6 × 10 ^-5 / ° C, 10 ⁷ to
10 ¹⁸ Ω · cm) Polyamide-imide resin (PAI) (280-290 ℃, 300
℃, 270 ~ 282 ℃, E86 ~ 104, 0.9 ~ 4.1 × 10 ^-5 /
℃, 0.8 × 20.3 × 10 ¹⁶ Ω · cm Polyetherimide resin (PEI) (200-210 ℃, 21
5 ~ 217 ℃, 200 ~ 210 ℃, M109, 1.4 ~ 5.6 × 10 ^-5
/ ° C., 10 ¹⁶ to 10 ¹⁷ Ω · cm) Polyether ketone resin (PEK) (165 to 170 ° C., 36
5 to 380 ° C, 168 ° C, −, −, −) Polyether ether ketone resin (PEEK) (145
℃, 335 ℃, 150 ℃, M98, 0.8 ~ 6.2 × 10 ^-5 / ℃, 1
0 ⁵ to 10 ¹⁷ Ω · cm) Polyphenylene sulfide resin (PPS) (90 ° C, 28
5 ~ 290 ℃, 105 ~ 136 ℃, R123, 0.6 ~ 6.3 × 10 ^-5
/ ° C, 10 to 10 ¹⁷ Ω · cm) 46 polyamide resin (46PA) (78 to 80 ° C, 290 ° C,
220 ℃, R118 ~ 121, 3 ~ 8.5 × 10 ^-5 / ℃ 10 ¹⁵ Ω
・ Cm) wholly aromatic polyester resin (POB, LCP) (-, 41
2 ℃, 180 ~ 355 ℃, R60 ~ 66, 0.1 ~ 12 × 10 ^-5 / ℃,
10 ² to 10 ¹⁷ Ω · cm) Tetrafluoroethylene resin (PTFE) (-, 327 ℃, 55
℃, Shore hardness D50 ~ 65, 3.9 ~ 18 × 10 ^-5 / ℃,> 10
¹⁷ Ω · cm) These have a glass transition temperature of at least 70 ° C and a melting point of at least 215 ° C (thermoplastic resin),
The structural material has a deflection temperature under load of at least 70 ° C. or higher, preferably 150 ° C. or higher. Each of these different types of resins has different heat resistance and hardness, and the combination is selected according to the specifications / conditions such as normal temperature, instantaneous maximum temperature and melting point, deflection temperature under load, and heat resistance temperature such as glass transition temperature. . As described above, the heat resistance temperature of the resin is preferably higher than the specification / condition temperature, and for safety, it is preferably about 30 ° C. to 60 ° C. or higher than the specification temperature. As the sliding material, a fluorocarbon resin such as a tetrafluoroethylene resin or a molten fluororesin, an aromatic polyester resin, or the like is a preferable material because it is excellent in friction and wear characteristics and is unlikely to cause stick slip. Such a resin material may be formed on the inner peripheral surface of the slide bearing 3 or the outer peripheral surface of the bush 8, and the bush 8 and the slide bearing 3 slide on the structural material 3A as shown in FIG. 3B. It may be a composite molded body of two kinds of materials with the moving material 3B. The sliding member 3B is formed as a sleeve fitted in the circular hole of the structural member 3A. This seems to be slightly disadvantageous in terms of cost, but has excellent wear resistance.

If the sliding bearing and the bush are made of a resin material of the same material or a resin material having relatively similar characteristics,
SP-based steel sheets such as SPCC, SPCD, SPCE, etc. may be interposed between the sliding surfaces as a measure against adhesion and creep, and such steel sheets are plated with nickel-based plating, chrome-based plating or the like. It may be a steel plate.

The bush material may be a molded body of the following ceramic material other than the heat resistant resin. In (), the maximum operating temperature and hardness (H
v) and the linear expansion coefficient. Alumina (aluminum oxide) (Al ₂ O ₃ ) (1600 to 1900 ° C, 1200 to 2300 Kgf / mm ² , 4.6 to 9.3 ×
10 ^-6 / ℃) Zirconia (ZrO ₂ ) (800 ℃, 1200 ~ 1500Kgf / mm ² , 9.5 ~ 11 × 10 ^-6 /
℃) Silica (quartz glass) (1150 ℃, −, 0.5 × 10 ^-6 / ℃) Silicon carbide (SiC) (1100 to 1600 ℃, 2000 to 2900 Kgf / mm ² , 3.1 to 5 × 10
^-6 / ℃) Silicon Nitride (Si ₃ N ₄ ) (1400-1500 ℃, 1500-1800Kgf / mm ² , 1.9-4 × 10
^-6 / ℃) Sialon (Si _6-Z Al _Z O _Z N _8-Z ) (Z = 0 ~
4.2) (-, 1800 to 2000 Kgf / mm ² , 2.8 to 3 x 10 ^-6 / ° C) Aluminum nitride (aluminum nitride) (AlN) (-, 1000 to 1200 Kgf / mm ² , 4.4 to 5.7 x 10 ^-6 / ° C) Titanium nitride (TiN) (-, 1200 to 1600 Kgf / mm ² ,-) Tungsten carbide (-,-,-)

These are super heat resistant and the heat insulating property is relatively excellent in the resin material, but the coefficient of linear expansion is about 1/10 smaller than that of the resin material. It is possible to provide a bearing device that is easy to make small and has high clearance accuracy. Particularly, when the bush and the roller are fitted together, the linear expansion coefficients of the two should be close to each other. Therefore, the difference between the linear expansion coefficient of the bush and the roller is within about Δα = 1 to 100 times, preferably Δα = 1.
It is preferable to set it within about 10 times. By applying to the bush a material having a coefficient of linear expansion that is relatively the same as that of the roller and having heat insulation, it is possible to increase the accuracy of the clearance between the bush and the roller, and It is possible to provide a high-temperature bearing device that has less rattling even when applied to a bearing for use, and that does not stress each member at low temperatures.

Although these new ceramics may be used for either or both of the slide bearing and the bush, these materials are selected for the bush which has a relatively high roller surface temperature and is strict. It is preferable to select the heat-resistant lubricating resin as the bearing material. This is because the resin material has a self-lubricating property as compared with ceramics, and thus has a lower friction coefficient and lower torque than sliding surfaces of ceramics, and the heat insulating property is also improved as compared with ceramics. In order to impart lubricity to ceramics as well, the sliding surface of the ceramic molded body is coated or impregnated with the above-mentioned lubricating resin by coating or the like, and at least the sliding surface of the ceramic is coated with the lubricating resin. Is also good. Among the ceramic materials, alumina has compressive strength of 100 to 450 Kgf / mm ² bending strength of 5 to 85 Kgf / mm ² Young's modulus of 2.5 to 4.8 × 10 Kgf / mm ² fracture toughness in addition to the above characteristics. 0-4.6 MN / m ^3/2 Poisson's ratio 0.19-0.26 Thermal conductivity 0.004-0.1 cal / cm ・ sec ・ ° C Impact resistance 180-500 ° C Specific heat 0.17-0.33cal / G · ° C, which seems to be relatively excellent on average in terms of mechanical strength, heat resistance, dimensional stability, price, etc.
The material is not particularly limited, as long as it is a bush having heat resistance, thermal characteristics of each material group described above,
A material having a linear expansion coefficient and hardness is preferable.

In the above embodiment, the sliding bearing 3 is mounted in the bearing mounting hole of the housing 4 in a fitted state. However, as shown in FIG. 3, the sliding bearing 3 is provided with mounting pieces 3c extending to both sides. You may make it attach to a housing with a screw member etc. which are penetrated by the attachment hole 12 provided in the attachment piece 3c. Further, as shown in FIG. 4, the rotation stopping means of the bush 8 includes a flat surface portion 13 formed at an end portion of the fixing roller 1,
It may be formed by the flat surface portion 14 formed on the inner diameter surface of the bush 8 and in contact with the flat surface portion 13. In addition, bush 8
May be fixed to the fixing roller 1 in a non-rotating state by press fitting, or the bush 8 may be rotatable together with the fixing roller 1 without being stopped. Even when co-rotating is possible, sliding will mainly occur at the contact surface with the sliding bearing 3 having a small contact resistance. The clearance of each relatively sliding portion depends on the size of the bearing, bush, etc., but can be set as follows. The gap between the rotary sliding bodies such as plain bearings and bushes is calculated by the following formula in consideration of the linear expansion coefficient of each material during high temperature operation ( _TH C). (1) housing an inner diameter _{Maximum: HH H = H H {1} + α 1 (T H -25)} _{Min: HH L = H L {1} + α 1 (T H -25)} (2) bearing outer diameter Maximum: SH _{H = S H {1 + α} 2 (T H -25)} _{Min: SH L = S L {1} + α 2 (T H -25)} (3) operating clearance

[0032]

[Equation 1]

[0033] Here, H _H: internal diameter maximum dimension H _L of the housing: the minimum inner diameter dimension of the housing S _H: the axis of the outer diameter maximum dimension S _L: axis of the outer径最small dimensions d _25H: bearing bore maximum dimension (25 ° C. ) d _25L: bearing bore minimum dimension _{(25 ℃) α 1: T} H linear expansion coefficient of the housing material in ° C. alpha _2: shaft member at T _H ° C., the linear expansion coefficient of the bush member alpha _3: bearing material at T _H ° C. Linear expansion coefficient of typical materials Linear expansion coefficient of copper: Approx. 0.9 to 1.2 × 10 ^-5 / ° C Aluminum: Approx 2.2. To 2.4 × 10 ^-5 / ° C Stainless steel: Approx. 1.7 to 1.8 × 10 ^-5 / C. The linear expansion coefficient of each resin material is as described above. In addition, the minimum clearance, when used in the unlubricated oil state,
Approximately 2 of the shaft diameter and bush diameter to reduce the effect of heat generation.
A gap of about 7/1000 or more may be provided. The sliding part may be in a non-lubricated state, but the initial wear of the sliding part until the transfer film is formed on the mating material of the sliding part is reduced as much as possible, and the life of the bearing is extended. The heat resistant grease may be applied to the sliding surface in a small amount, for example, about 0.1 to 1 gram, so that the rotation torque is not reduced. The fixing device is classified into a dry type and a wet type of oil application, and the paper is passed through the device to fix the toner on the paper. In order to eliminate the heat-resistant grease, it is not necessary to apply the heat-resistant grease, and even if the grease is small, the rotation of the fixing roller 1 or the like as shown in FIG. A step means such as a flange 8b or a retaining ring 9 may be provided on the body or a rotary sliding body such as a slide bearing or a bush to prevent the grease from damming.

In the bearing structure according to the present invention, a recording pattern is formed on a medium such as a photoconductor by an electric signal given from the outside, and the pattern of the electric quantity formed on the medium is made into a visible pattern. Of course, the present invention can be applied to printers that employ various conversion methods. Examples of such a printer system include an electrophotographic system, an inkjet system, a thermal system, an optical printer system, and an electronic recording system. The types of electrophotography described above include the Carlson method, light / charge injection method, optical polarization method, photovoltaic method, charge transfer method, electrolytic electrophotography method, electrostatic latent image photography method, photoelectrophoresis method, thermostat method. The plastic method can be mentioned. Further, as an optical printer, a laser printer, LE
Examples include D (light emitting diode) printers, liquid crystal shutter printers, and CRT printers. Further, examples of the electronic recording method include an electrostatic recording method, an electrification recording method, an electrolytic recording method, and an electric discharge recording method, and further include a direct method and an indirect method. In addition, there are methods such as a wet method of applying oil and the like and a dry method of the electrostatic recording method.

Specifically, a toner image transfer type dry electrostatic copying machine, a wet electrostatic copying machine, a laser beam printer (L
BP), liquid crystal shutter (LCD) printer, facsimile printer, PPC, light emitting diode (LE)
D) is a general concept of the image forming apparatus such as a printing machine such as a printer such as a silver salt photographic printer (CRT).

The bearing structure according to the present invention is not particularly limited in its use parts such as the paper feed part, the photo-sensitive part, the fixing part and the paper discharge part. In addition to the pressure roller, it can be applied not only to the pressure roller but also to the fixing roller that is used at high temperature, and since it is a heat-resistant resin that can be injection-molded, the complicated shape of the present invention (see FIGS. 2 to 4) However, it is possible to provide a bearing structure that can be easily molded, is efficient in terms of productivity, and is inexpensive.

[0037]

According to the bearing structure for high temperature such as the heat fixing device of the present invention, a bush made of a heat resistant material is interposed between the slide bearing and the rotating body such as the fixing roller, and the bush and the slide bearing are interposed between the bush and the slide bearing. Since the sliding contact is performed by the sliding contact, unlike the sliding contact on the surface of the fixing roller, abrasion of the sliding bearing and the fixing roller due to the so-called screw action of the fixing roller is prevented, and stress due to temperature fluctuation of the sliding bearing is mitigated, Therefore, the durability of the rotating body such as the slide bearing and the fixing roller is improved.

[Brief description of drawings]

FIG. 1A is a partially cutaway front view of a heating and fixing device to which a bearing structure according to an embodiment of the present invention is applied, and FIG. 1B is an enlarged sectional view of a part thereof.

FIG. 2 is an exploded perspective view showing a relationship among a fixing roller, a bush, and a slide bearing in the embodiment.

FIG. 3A is a perspective view showing a slide bearing according to another embodiment, and FIG. 3B is a perspective view showing a slide bearing according to still another embodiment.

FIG. 4 is an exploded perspective view showing a relationship between a fixing roller and a bush in still another embodiment.

FIG. 5 is a cross-sectional view of a conventional example.

FIG. 6 is a cross-sectional view of another conventional example.

FIG. 7 is a cross-sectional view of still another conventional example.

[Explanation of symbols]

1 ... Fixing roller, 2 ... Heater, 3 ... Sliding bearing, 3a ... Bearing surface, 4 ... Housing, 6 ... Pressure roller, 8 ... Bushing, 8a ... Key

Claims (5)

[Claims] 1. In a high temperature bearing structure in which a shaft is rotatably supported by a slide bearing, a bush made of a heat resistant material is rotatably contacted with the slide bearing between the slide bearing and the shaft. The bearing structure for high temperature is characterized in that 2. A bearing structure of a heat fixing device in which a fixing roller having a built-in heater is rotatably supported by a slide bearing at an end thereof, and a fixing structure is provided between the slide bearing and the fixing roller.
A bearing structure of a heat fixing device, wherein a bush made of a heat-resistant material is interposed so as to rotatably contact the slide bearing. 3. The bearing structure according to claim 1, wherein the bush is made of a material having higher heat resistance than the slide bearing. 4. The bearing structure according to claim 1, 2, or 3, wherein the bush is made of ceramics. 5. The bearing structure according to claim 1, 2, or 3, wherein the bush is a resin material having heat resistance higher than a shaft surface temperature.