JP2001254733A - Rolling bearing for electophotographic process equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the design versatility of a roll equipped on electrophotograhic process equipment, and to reduce the creep between an inner ring of a bearing and a heat insulation bush. SOLUTION: In a rolling bearing which supports a fixing roller of the electrophotographic process equipment, the inside diameter of the inner ring 1 is set to be >=20 mm to <=35 mm, and the ratio [B/H] of the bearing width B to the sectional height H is set to be >=1.5 to <=2.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine (digital PPC, color PPC, etc.) and a printer (color LPC).
The present invention relates to a rolling bearing that rotatably supports a roll provided in an electrophotographic process device such as a BP and a color LED.

[0002]

2. Description of the Related Art An electrostatic transfer copying machine is equipped with a number of rolls such as a photosensitive drum, a developing drum, a fixing roller, a pressure roller, a heat roller, and a paper feed roller.

FIG. 6 shows a fixing roller 26 as an example of the various rolls. The fixing roller 26 is rotatably supported by the mounting frame 12 by a pair of rolling bearings 11 (for example, deep groove ball bearings shown in FIG. 7) mounted on both shaft ends. The inner ring 1 of the rolling bearing 11 is fitted to the shaft end of the fixing roller 26 via the heat-resistant bush 14 and is locked in the axial direction by the retaining ring 15. Further, the outer ring 2 of the rolling bearing 11 is fitted on the inner periphery of a mounting frame 12 made of a steel plate, and is locked in the axial direction by a retaining ring 17. A retaining ring 17 that locks the outer ring 2 is fitted in a retaining ring groove 2b formed on the outer diameter surface of the outer ring 2, and abuts the end surface of the mounting frame 12 in the axial direction. Is positioned with.

[0004]

However, in recent years,
In many cases, a four-tandem tandem system in which four photosensitive drums are juxtaposed is used in an image forming unit of a color printer, a color copier, or the like. The quadruple tandem system is a single light source system shown in FIG.
Unlike the method of developing each color in (3), each color is developed on each of the four photosensitive drums, and has a merit that a high-speed output is possible because of a simple process and a short paper feed line.

On the other hand, the four-tandem tandem system tends to be mechanically large and complicated due to an increase in the number of drums. Therefore, when the four-tandem tandem system is employed while maintaining the conventional copying machine size, each of the four-tandem tandem systems is required. Further downsizing of components is required. Rolling bearings that support the rolls also need to be miniaturized. In particular, there is a strong demand to reduce the outer diameter to increase the degree of design freedom around the bearings.

However, in recent years, the load applied to the roll tends to increase with the progress of high speed operation. Therefore, it is not possible to secure a sufficient load capacity simply by replacing the bearing with a small-diameter bearing. It hinders the response to the change.

Although the pressing force in the fixing section also tends to increase due to the increase in speed, the heat insulating bush inserted between the bearing inner ring of the bearing supporting the fixing roller and the roller shaft is formed of a resin material having low rigidity. Therefore, it is difficult to improve the radial load capacity of the fixing roller, and it is not possible to sufficiently meet the demand for high speed.

Furthermore, since the resin heat-resistant bush is fitted into the inner peripheral surface of the bearing inner ring with a clearance fit in consideration of the difference in the amount of thermal expansion between the heat-insulating bush and the inner ring. Is likely to occur, and there is a concern that the hammer eye surface may be worn (especially on the heat insulating bush side).

Further, since the fixing roller shaft 26a is often made of aluminum, it is easily bent, and this bending may adversely affect image accuracy.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a rolling bearing suitable for an electronic process device, particularly a developing unit and a fixing unit of a quadruple tandem system.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a rotatable roll mounted on an electrophotographic process device, comprising a plurality of inner and outer rings and a plurality of rollers interposed between the inner and outer rings. The inner diameter of the inner ring is not less than 20 mm and not more than 35 mm, and the ratio B / H of the width B of the bearing to the section height H is not less than 1.5 and not more than 2.0. It was done. "Width dimension B" here
Represents the axial width of the outer ring, and the "section height H" is
(Outer diameter of outer ring−Inner diameter of inner ring) / 2.

A conventional rolling bearing for electrophotographic process equipment generally has a B / H of about 1.0 to 1.2. In the present invention, this value is set to 1.5, which is higher than that of a conventional product. ≤
B / H ≦ 2.0 was set. As B / H increases, the degree of flatness of the bearing increases, and the bearing becomes thinner and wider (has a large axial dimension). Therefore, according to the present invention, the inner diameter is the same as that of the conventional product. Even so, the outer diameter of the bearing can be reduced, and the free space in the radial direction can be increased to increase the degree of freedom in designing the periphery of the bearing. In addition, since the width B of the bearing is sufficiently ensured, it is possible to increase the amount of filled grease, to reduce the surface pressure of the contact, and to suppress a decrease in load capacity.

Even when a resin heat insulating bush is arranged on the inner periphery of the bearing inner ring, the frictional force acting on the sword eye surface increases due to the increase in the width B, so that the creep between the slash eye surfaces is reduced to reduce the wear. It can also be suppressed. Furthermore, since the width of the area (roller support area) that supports the roller shaft in the inner circumference of the bearing inner ring increases in the axial direction,
Shaft deflection is also suppressed, contributing to image stabilization.

When the diameter of the bearing is reduced in the conventional product shown in FIG. 7, the area where the retaining ring groove 2b is formed is close to the outer diameter area of the outer ring raceway surface 2a, and it is difficult to machine the retaining ring groove 2b due to insufficient wall thickness. However, by increasing the width dimension B as in the present invention, it is easy to perform the retaining ring groove processing outside the outer diameter region of the outer ring raceway surface 2a, and to secure a sufficient wall thickness to improve workability and outer ring. It is possible to improve the strength.

If the B / H ratio is less than 1.5, it may not be possible to secure the minimum thickness required for forming the retaining ring groove on the outer ring, and if H is too large. ,
The outer diameter cannot be reduced. On the other hand, B / H
When the ratio exceeds 2.0, the grease is not sufficiently supplied to the raceway surface because the width dimension is too large, the incorporation of the ball is deteriorated, and the assembling becomes difficult, and the occupied space in the axial direction becomes so large that it cannot be ignored. When the bearing is tilted due to roll deflection or the like, the seal 5 or 6 on one side comes into contact with the inner ring 1 to increase the torque, and it becomes difficult to confirm the ball at the time of shipping inspection.

This rolling bearing for electrophotographic process equipment is a bearing that rotatably supports a roll (including a photosensitive drum as well as a developing drum) provided in a developing unit of a quadruple tandem system or a roll of a fixing unit. It is suitable as.

Number of rolling elements of rolling bearing and PCD (mm)
The ratio [PCD / (number of rolling elements)] is preferably 1 or more. The larger this value is, the smaller the number of rolling elements is, so that the manufacturing cost can be reduced.

Further, a roll device according to the present invention includes a roll mounted on an electrophotographic process device, a housing, and the above-described rolling bearing for an electrophotographic process device rotatably supporting the roll with respect to the housing. It is.

This roll device is particularly preferable when the developing section of the electrophotographic process equipment is of a quadruple tandem type, or when the roll is a roll of a fixing section.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
A description will be given based on FIG.

FIG. 1 conceptually shows a color copying machine having a laser exposure type quadruple tandem image forming section 30, in which four photosensitive drums 31 are arranged in parallel along an endless belt-like transfer member 37. Have been. A charging electrode 34 is provided around each photosensitive drum 31, and yellow (Y), magenta (M), and cyan (C) obtained by color-separating document image information are provided on the downstream side in the rotation direction of the charging electrode 34. , Black (BK)
An exposure device 32 that forms an electrostatic latent image by exposing each of the color signals to the photosensitive drum 31 by laser exposure is provided. Further, on the downstream side in the rotation direction of the photosensitive drum 31, a developing unit 33 for developing with the developer (toner) of each color is disposed, and on the downstream side, a transfer electrode 35 is disposed.

When the original is scanned by an irradiating means (not shown), the photosensitive drum 31 rotates in the direction of the arrow,
4 is charged to a constant voltage. Next, each photosensitive drum 31 is irradiated with a laser beam of each color obtained by color-separating the original image from the exposure device 32, and an electrostatic latent image of each color is formed on the photosensitive drum 3.
1 is formed on each surface. Here, toner of each color having the opposite polarity charge adheres from the developing drum 33a of the developing unit 33 to form a visible image, and each visible image is sequentially multiplex-transferred to the transfer member 37 by charging the transfer electrode 35. 37
Is transferred to paper (shown by a broken line). The electrostatically attracted state between the transfer body 37 and the paper is released by the separation electrode 39, and the paper is sent to the fixing unit 25, where the fixing roller 26 and the pressure roller 27 heat and pressurize the toner image. To be fixed.

FIG. 2 exemplifies a rolling bearing for rotatably supporting a fixing roller 26 on a steel plate mounting stay 12 (see FIG. 6) serving as a housing in a fixing section 25 of the electrophotographic process apparatus. . In this embodiment, as the rolling bearing, a deep groove ball bearing is exemplified. The deep groove ball bearing includes an inner ring 1 fixed to a shaft-side member such as a heat-resistant bush 14 (see FIG. 6), and a mounting frame 12.
And the like, a ball 3 as a rolling element interposed between a raceway surface 1a of the inner race 1 and a raceway surface 2a of the outer race 2, and the balls 3 are held at equal circumferential intervals. Main components are a retainer 4 and a pair of seals 5 and 6 for sealing the openings between the inner and outer rings 1 and 2 at both ends of the bearing. Although a non-contact type seal is shown as the seals 5 and 6 provided at both ends of the bearing, a contact type seal may be used. The bearing internal space S sealed with the seals 5 and 6 is filled with grease (not shown).
Various greases such as urea, silicone and fluorine can be used. In a rolling bearing for the fixing roller 26 used in a high-temperature atmosphere (about 200 ° C.), it is desirable to use fluorine grease excellent in high-temperature durability.

Since the shaft diameter of the rollers mounted on the electrophotographic process equipment is generally 20 to 35 mm, the inner diameter of the bearing (the inner diameter of the inner ring) is also adopted in the range of 20 mm or more and 35 mm or less. The ratio B / H of the axial width B of the outer race 2 to the cross-sectional height H is set to 1.5 or more and 2.0 or less. Here, the “section height H” means (the outer diameter dimension D of the outer ring−the inner diameter dimension d of the inner ring) / 2. The diameter series of the bearing in the illustrated example is 7.

By setting the B / H ratio in this way,
Since the outer diameter D of the outer ring 2 is smaller than that of the conventional product in which the inner diameter d of the inner ring 1 is equal, the required space in the radial direction is reduced, and the degree of freedom in designing the peripheral structure at both ends of the fixing roller 26 is increased. Becomes possible. Further, in the conventional product, when the outer diameter D of the bearing is limited, it may be difficult to arrange the heat insulating bush 14. However, even in the case of the same outer diameter D, the inner diameter d of the bearing increases. Therefore, the heat insulating bush 14 can be arranged.

Since the width B of the bearing is larger than that of the conventional product, the surface pressure between the bearing inner ring 1 and the heat insulating bush 14 is reduced. In this case, since the roller support region expands in the axial direction, the bending of the roller shaft 26a is suppressed, and the image is stabilized. Further, since the frictional force acting on the hammer-eye surfaces of the inner ring 1 and the heat insulating bush 14 also increases, the creep between the hammer-eye surfaces can be reduced and the abrasion thereof can be suppressed.

In the above-structured deep groove ball bearing, the ball 3
The number of the balls 3 can be arbitrarily selected as long as it is at least three or more, as long as it can be incorporated between the inner and outer rings 1 and 2. However, in order to reduce costs, the number of the balls 3 should be as small as possible. Is desirable.

FIG. 3 shows the shaft runout (center of the bearing) due to the passage of the ball when the radial load (9.8 N) is applied when the number of balls 3 of the product of the present invention shown in FIG. 2 is 24, 16, or 12. (Change in position). “Skip” in the figure represents the radial gap of the bearing. As shown in the figure, the difference in shaft runout due to the difference in the number of balls is as small as about 1 μm or less. Therefore, even when the number of balls is reduced, the shaft runout characteristics are hardly affected. FIG. 4 shows that the outer ring 2 is
The radial deformation of the bearing when pressed in the radial direction at N is measured. From the figure, the radial deformation due to the difference in the number of balls is almost the same. In any case, the ratio of the PCD (mm) to the number of balls [PCD / (number of balls)] is 1 or more.
Since the radial load actually applied to the roller of a copying machine or a printer is substantially equal to or greater than this, even if the number of balls is reduced within a range satisfying the above ratio,
It is considered that the shaft runout and the amount of elastic deformation of the bearing are hardly affected.

In the above description, the case where the present invention is applied to the bearing for the fixing roller 26 is exemplified. However, the present invention is not limited to this, and other rolls provided in the electrophotographic process equipment, for example, Pressure roller 27, photosensitive drum 3
The present invention can be widely applied to a rolling bearing for supporting a roll such as a developing drum 33a or the like.

[0030]

As described above, according to the present invention, since the outer diameter of the rolling bearing is smaller than that of the conventional product, the degree of freedom in designing the periphery of the roll in the electrophotographic process equipment is increased, and the peripheral structure is further improved. Compactness can be achieved. At the same time, the deflection of the roller shaft due to the radial load can be reduced, and a highly accurate visible image can be obtained. Further, it is possible to suppress the creep between the bearing inner ring and the shaft member fitted to the inner circumference thereof, and the wear of the hammer-eye surface due to this,
Roll life can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view conceptually showing a quadruple tandem system.

FIG. 2 is a sectional view of a rolling bearing according to the present invention.

FIG. 3 is a diagram showing a calculation result of shaft runout due to a difference in the number of balls.

FIG. 4 is a view showing a result of measuring a radial deformation amount of a bearing due to a difference in the number of balls.

FIG. 5 is a sectional view conceptually showing a single light source system.

FIG. 6 is a sectional view of a fixing unit of the copying machine.

FIG. 7 is a sectional view of a conventional rolling bearing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner ring 1a Inner ring raceway surface 2 Outer ring 2a Outer ring raceway surface 3 Rolling element (ball) 4 Cage 5 Seal 6 Seal 25 Fixing unit 26 Fixing roller 33 Developing unit B Width dimension H Sectional height

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/20 103 G03G 15/20 103 3J103 (72) Inventor Tsukasa Toyoda Omida 3066 F-term in NTT Co., Ltd.

Claims (7)

[Claims] 1. A rolling bearing rotatably supporting a roll mounted on an electrophotographic process device and having an inner ring and an outer ring, and a plurality of rolling elements interposed between the inner and outer rings, wherein the inner diameter of the inner ring is A rolling bearing for electrophotographic process equipment having a ratio of B / H of width B to cross-section height H of 1.5 to 2.0 which is not less than 20 mm and not more than 35 mm. 2. The rolling bearing for an electrophotographic process device according to claim 1, wherein a roll provided in a four-tandem developing unit is rotatably supported. 3. The rolling bearing for an electrophotographic process device according to claim 1, wherein the roller of the fixing unit is rotatably supported. 4. The ratio [P] between the number of rolling elements and PCD (mm).
4. The rolling bearing according to claim 1, wherein CD / (number of rolling elements)] is 1 or more. 5. A roll provided in an electrophotographic process device, a housing, and the rolling bearing for an electrophotographic process device according to claim 1, which rotatably supports the roll with respect to the housing. Roll device. 6. The roll device according to claim 5, wherein the developing section of the electrophotographic process device is of a four-tandem type. 7. The roll device according to claim 5, wherein the roll is a roll of a fixing unit.