JP2000275994A - Roller supporting structure for fixing device and rolling bearing for fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of erroneous alignment. SOLUTION: An outer ring 3b is provided with a part having a difference in level 7 at one end part of an outer diameter surface. The part 7 is constituted of a vertical wall 7a whose squareness to an axial line X is controlled with required accuracy and an outside diameter wall 7b which is in parallel with the axial line X and also whose outside diameter is controlled with the required accuracy. The outer ring 3b is attached to an attaching frame 2 in a state where the outside diameter wall 7b of the part 7 is fitted in the inner periphery 2a of the attaching frame 2 and the vertical wall 7a abuts on the end surface 2b of the attaching frame 2. A rolling body 3c may be formed of a ceramic material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrostatic transfer copying machine,
In a fixing device such as a laser printer, an ADF, a sorter, and an RDH, the present invention relates to a support structure for rotatably supporting a roller with respect to a mounting member and a rolling bearing used for the support structure.

[0002]

2. Description of the Related Art For example, a fixing device of an electrostatic transfer copying machine is a device for fixing a toner image transferred on a sheet to a sheet, and is mainly composed of a fixing roller and a pressure roller. The fixing roller has a heater inside, and fixes the toner image transferred to the sheet by heating the toner image onto the sheet. The pressing roller is disposed in parallel with the fixing roller while pressing the fixing roller, and rotates following the fixing roller. The pressure roller has a role of stabilizing the toner image that has been heated and fixed on the sheet by the fixing roller.

FIG. 3 shows a conventional fixing roller support structure. The fixing roller 11 is rotatably supported on the mounting frame 12 by a pair of rolling bearings 13 mounted on both shaft ends. The inner ring 13a of the rolling bearing 13 is fitted to the shaft end of the fixing roller 11 via a heat-resistant bush 14, and is locked in the axial direction by a retaining ring 15. Also,
The outer ring 13b of the rolling bearing 13 is fitted on the inner periphery of the mounting frame 12, and is locked in the axial direction by a retaining ring 16. The retaining ring 16 is fitted in a retaining ring groove formed on the outer diameter surface of the outer ring 13b, and axially contacts the end surface of the mounting frame 12 to position the outer ring 13b in the axial direction.

[0004]

The conventional structure in which the outer ring 13b of the rolling bearing 13 is locked to the mounting frame 12 by the retaining ring 16 has the following problems.

[0005] (1) The flatness of the width surface of the retaining ring 16 is not very high, and there is a slight axial gap between the retaining ring 16 and the retaining ring groove.

(2) When an axial load exceeding the fitting force of the retaining ring 16 into the retaining ring groove is applied due to thermal displacement of the fixing roller 11 or the like, the retaining ring 16 elastically expands its diameter to support the axial load. Therefore, the perpendicularity to the fixing roller 11 cannot be maintained.

(3) According to the circumstances (1) and (2),
Misalignment occurs between the inner ring 13a and the outer ring 13b of the rolling bearing 13, which tends to shorten the life of the rolling bearing 13 in combination with a high ambient temperature.

(4) By increasing the width of the retaining ring 16 and increasing the fitting force to the retaining ring groove, the allowable range for the axial load can be increased.
In some cases, the raceway surface of the outer ring 13b is deformed, which may impair the bearing function.

(5) In the conventional structure in which the outer ring 13b is provided with a retaining ring groove, there is a limit to downsizing due to the problem of the strength of the outer ring.

An object of the present invention is to solve the above-mentioned problem of misalignment in the conventional structure, improve the bearing life, and provide a more compact roller support structure.

[0011]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention relates to a roller supporting structure of a fixing device in which a shaft end of a roller is rotatably supported with respect to a mounting member by a rolling bearing. A step is provided on the outer diameter surface of the outer ring,
The stepped portion is brought into contact with the mounting member in the axial direction to perform the axial positioning of the outer race.

Further, the present invention includes an inner ring mounted on a shaft end of a roller of the fixing device, and an outer ring mounted on a mounting member, and rotatably supports the shaft end of the roller with respect to the mounting member. In the rolling bearing for a fixing device described above, a step portion is provided on the outer diameter surface of the outer ring so as to abut the mounting member in the axial direction to position the outer ring in the axial direction.

In the above-mentioned rolling bearing, particularly when the roller is a heat roller for heating and fixing a toner image, the rolling element disposed between the inner and outer rings is preferably formed of a ceramic material. In this case, it is desirable to form the inner ring by quenching steel containing Si or Al and having an oxygen content of 13 ppm or less and then tempering at a high temperature of 230 ° C to 300 ° C.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a support structure of the fixing roller 1 in the fixing device. The fixing roller 1 has a double shaft end 1a.
Is rotatably supported by a pair of rolling bearings 3 mounted on a mounting frame 2 as a mounting member. A resin layer 1 b made of a resin material such as PTFE is formed on the outer periphery of the fixing roller 1.
And a heater 1c is provided inside. Also,
A driving gear 4 (or sprocket) is connected to (or integrally provided with) one end of the fixing roller 1.

FIG. 1 shows a rolling bearing 3 that rotatably supports a shaft end 1 a of a fixing roller 1 with respect to a mounting frame 2. The rolling bearing 3 includes an inner ring 3a mounted on the shaft end 1a of the fixing roller 1, an outer ring 3b mounted on the mounting frame 2, a raceway surface 3a1 of the inner ring 3a, and an outer ring 3b.
A plurality of rolling elements, for example, a ball 3c, a retainer 3d for holding the ball 3c at a predetermined circumferential position, and a pair of seal members 3e for sealing the inside of the bearing.
And Grease is sealed inside the bearing.

The inner ring 3a is fitted to the outer periphery of the shaft end 1a of the fixing roller 1 via, for example, a heat-resistant bush 5, and is axially locked by a retaining ring 6 fitted to the outer periphery of the shaft end 1a. You. That is, the inner ring 3a and the retaining ring 6 are not in contact with each other.

The outer race 3b has a step 7 at one end of the outer diameter surface. The step portion 7 is composed of a vertical wall 7a whose perpendicularity to the axis X is controlled to required accuracy, and an outer diameter wall 7b parallel to the axis X and whose outer diameter is controlled to required accuracy. The outer ring 3b is mounted on the mounting frame 2 with the outer diameter wall 7b of the stepped portion 7 fitted to the inner periphery 2a of the mounting frame 2 and the vertical wall 7a abutted on the end face 2b of the mounting frame 2.
Attached to.

The vertical wall 7a of the stepped portion 7 abuts against the end face 2b of the mounting frame 2, whereby the axial position of the outer race 3b and the perpendicularity to the mounting frame 2 and the axis X are secured with required accuracy. Outer diameter wall 7 of step 7
By fitting b with the inner circumference 2a of the mounting frame 2, the radial position of the outer ring 3b is secured with required accuracy.
Also, the vertical wall 7a of the step portion 7 is not affected by the axial load.
And the end surface 2b of the mounting frame 2 abuts and supports the mounting frame 2, so that the allowable range for the axial load is wide, and misalignment due to thermal displacement of the fixing roller 1 and the like hardly occurs. Furthermore, compared with the conventional structure in which a retaining ring groove is formed on the outer diameter surface of the outer ring, in securing the minimum thickness of the outer ring 3b (the thickness of the portion where the distance from the outer surface to the raceway surface 3b1 is minimum). This is advantageous, and it is possible to reduce the size of the bearing while maintaining the same level of strength as in the related art, thereby making it possible to reduce the size of the support structure. The axial dimension of the outer diameter wall 7b of the stepped portion 7 is preferably about 20% of the axial dimension of the outer ring 3 in order to secure the strength of the outer ring 3b, to reduce the size, and to suppress the processing cost.

FIG. 4 shows another embodiment of the rolling bearing 3. In this embodiment, the step portion 7 on the outer diameter surface of the outer ring 3b is provided at an end located on the center side of the fixing roller 1. Compared with the configuration shown in FIG. 1, there is an advantage that the mounting work on the mounting frame 2 is facilitated.

FIG. 5 shows another embodiment of the rolling bearing 3. As in the embodiment shown in FIG. 4, the stepped portion 7 of the outer diameter surface of the outer ring 3 b is provided at the end located at the center side of the fixing roller 1. A portion near the periphery is bent to form a cylindrical portion 2c, and the inner periphery of the cylindrical portion 2c is fitted to the outer diameter surface of the outer ring 3b. There is an advantage that the radial position of the outer ring 3b with respect to the mounting frame 2 is more stable than the configuration shown in FIGS.

By the way, the heat-resistant bush 5 protects other parts from the heat of the fixing roller 1.
Is used to maintain the heat balance (maintain the balance) of the fixing roller 1 and the mounting frame 2 to insulate the fixing roller 1 and secure the charging property of the fixing roller 1. A slit is provided in the axial direction to release thermal expansion at the time. When there is a gap between the inner ring 3a and the heat-resistant bush 5 or between the heat-resistant bush 5 and the shaft end 1a, noise may be generated by opening or closing the slit of the heat-resistant bush 5. is there. In such a case, the inner surface 3a and the end surface of the inner ring 3a are coated with a fluorine-based resin or grease to secure the charging property (insulation property) of the fixing roller 1 and at the same time generate the abnormal noise. However, it is difficult to completely prevent the generation of abnormal noise, and this leads to an increase in man-hours and an increase in cost.

As a solution to this problem, as shown in FIG. 6, it is conceivable to form the rolling element 3c of the rolling bearing 3 from a ceramic material. In this case, the inner ring 3 of the rolling bearing 3
a shows the fixing roller 1 without using the heat insulating bush 5;
Is mounted directly on the shaft end 1a. Shaft end 1a of inner ring 3a
The inner peripheral surface of the inner race 3a is fixed to the shaft end 1 as shown in the figure.
In addition to press-fitting to the outer peripheral surface of a, it may be performed using a retaining ring 6 as in FIG.

Since the ceramic material has excellent properties of insulation and heat insulation, the above functions are not impaired even if the heat-resistant bush 5 is omitted as described above. Since the heat-insulating bush 5 can be omitted, the generation of abnormal noise can be completely prevented by eliminating the sound source, and the cost can be reduced by reducing the number of parts and the number of assembly steps. Further, a longer life of the bearing, which is a general effect when a ceramic material is used, is also achieved. When the heat insulating bush 5 is omitted as described above, how to secure the insulating property of the fixing roller 1 becomes a problem.
Although an attempt has been made to ensure insulation by using an insulating material in places other than the above, such an insulating structure is not necessary if the above structure is used.

On the other hand, since the thermal conductivity of the ceramic material is about 1/10 of that of the steel material, when the rolling element 3c is formed of the ceramic material as described above, the heat from the fixing roller 1 easily accumulates on the inner race 3a. It is feared that the bearing function may be adversely affected. Therefore, in this case, for example, a steel material disclosed in Japanese Patent Publication No. 6-33441 is preferably used as the material of the inner ring 3a. This steel material contains Si or Al, and after quenching steel having an oxygen content of 13 ppm or less, 230%
Tempered at a high temperature of 300C to 300C, and has long life, high heat resistance, and long-term dimensional stability.

Specifically, the above steel materials are, by weight, 0.95% to 1.10% of carbon, 1-2% of silicon or aluminum, 1.15% or less of manganese, 0.90% or less of chromium.
After quenching a steel material that is 1.60%, balance iron and impurities and has an oxygen oil content of 13 ppm or less, 230 ° C.
Tempering is performed at a high temperature of up to 300 ° C. to reduce the retained austenite to 8% or less and the hardness to 60 HRC or more. In this case, the steel structure may be carburized simultaneously with the quenching.

Of course, the material of the inner ring 3a is not limited to the above as long as it is a material having high heat resistance. For example, a bearing steel (SUJ material) modified to improve heat resistance can be used.

Although each of the embodiments described above relates to a fixing roller supporting structure in a fixing device, the present invention is similarly applicable to a pressing roller supporting structure in a fixing device.

[0029]

The present invention has the following effects.

(1) Since the outer ring is positioned in the axial direction by abutting the step portion provided on the outer diameter surface of the outer ring with the mounting frame, the mounting accuracy of the outer ring to the mounting frame is secured as compared with the conventional structure. This is easy and the work of mounting the retaining ring for locking the outer ring becomes unnecessary, so that the assembling process is simplified.

(2) Since the axial load can be supported by the contact between the stepped portion provided on the outer diameter surface of the outer ring and the mounting frame, the allowable range for the axial load is wide, and errors due to the thermal displacement of the roller and the like. Alignment is less likely to occur.

(3) The misalignment is less likely to occur, thereby increasing the life of the rolling bearing.

(4) Compared with the conventional structure, it is advantageous in securing the minimum thickness of the outer ring, and the roller support structure is compact by reducing the bearing size while maintaining the same strength as the conventional one. Can be achieved.

(5) Since the rolling element is formed of a ceramic material, a heat-resistant bush is not required, the generation of abnormal noise can be reliably prevented, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a rolling bearing according to an embodiment.

FIG. 2 is a cross-sectional view illustrating a roller support structure according to the embodiment.

FIG. 3 is a cross-sectional view showing a conventional roller support structure.

FIG. 4 is a sectional view showing a rolling bearing according to another embodiment.

FIG. 5 is a sectional view showing a rolling bearing according to another embodiment.

FIG. 6 is a sectional view showing a rolling bearing according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing roller 1a Shaft end part 2 Mounting frame 3 Rolling bearing 3a Inner ring 3b Outer ring 5 Heat resistant bush 7 Stepped part

Claims (6)

[Claims] 1. A roller supporting structure of a fixing device in which a shaft end of a roller is rotatably supported by a mounting member with respect to a mounting member, wherein a step portion is provided on an outer diameter surface of an outer ring of the rolling bearing. A roller supporting structure of the fixing device, wherein the outer ring is axially contacted with the mounting member to perform axial positioning of the outer ring. 2. The roller support structure of a fixing device according to claim 1, wherein the rolling element disposed between the inner ring and the outer ring of the rolling bearing is formed of a ceramic material. 3. The inner race of a rolling bearing is made of Si or Al.
3. The roller support structure of a fixing device according to claim 2, wherein the steel is quenched at a high temperature of 230 ° C. to 300 ° C. after quenching steel having an oxygen content of 13 ppm or less. 4. A fixing device comprising: an inner ring mounted on a shaft end of a roller of a fixing device; and an outer ring mounted on a mounting member, wherein the fixing device rotatably supports the shaft end of the roller with respect to the mounting member. A rolling bearing for a fixing device, wherein a stepped portion is provided on an outer diameter surface of the outer race in the axial direction so as to abut against the mounting member to position the outer race in the axial direction. 5. The rolling bearing for a fixing device according to claim 4, wherein the rolling element disposed between the inner ring and the outer ring is formed of a ceramic material. 6. After quenching steel whose inner ring contains Si or Al and has an oxygen content of 13 ppm or less,
The rolling bearing for a fixing device according to claim 5, wherein the bearing is tempered at a high temperature of 230C to 300C.