JP2000145798A - Bearing with sealing function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To integrally form a rubber seal and also an O-ring to reduce the manhours of assembling or the cost. SOLUTION: In an elastomer bearing having an outside surface 11 to be mounted on a housing and an inside surface 8 for supporting a rotating shaft, an annular lip part 9 protruded radially inward from one end side of the inside surface 8 is integrally formed to the circumferentially extended and annularly continued protruding part 10 of the outside surface 11. As the material of such a bearing with sealing function, a thermoplastic elastomer with a JIS-A hardness ranging from 70 to 90 or a thermoplastic elastomer-containing composition with a JIS-A hardness ranging from 70 to 90 is preferably used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing with a seal function suitable for use in a developing section of a copying machine, a printer, a facsimile, or the like, in a portion which comes into contact with fine powder such as toner.

[0002]

2. Description of the Related Art A conventional bearing 21 having a sealing function is used in a developing section of a copying machine, a printer, a facsimile or the like as described above, for use in a portion which comes into contact with toner which is a fine powder.
Has a configuration in which a rubber seal 23 and an O-ring 24 are mounted on a bearing body 22, as shown in FIG. 4, in order to prevent the toner from flowing out of the developing section and to prevent toner from entering the bearing section. .

The bearing body 22 has an outer diameter portion 27 for mounting in the opening 30 of the housing, a flange portion 28, and an inner diameter portion 26 for supporting the rotating shaft, thereby reducing sliding resistance with the shaft. Therefore, an oil-free resin bearing made of polyacetal or the like to which a lubricant such as oil is added is used.

The rubber seal 23 is made of nitrile rubber, has an annular lip 25 protruding in the axial direction, and is mounted on the bearing body 22 so as to abut the outer periphery of the rotating shaft.
The toner is prevented from entering the inner diameter portion 26.

As described above, since the oil-free resin bearing used for the bearing body 22 is generally one having a JIS-A hardness of 90 or more, when fitted into the opening 30 of the housing, the outer diameter portion 27 is formed. A gap is formed along the opening 30,
The toner leaks from such a gap. In order to prevent such leakage of toner, O
A ring 24 is attached to seal between the opening 30 and the outer diameter portion 27.

Therefore, even if the toner rushes to the bearing portion, the inner peripheral surface is covered with the rubber seal 25 and the outer peripheral surface is covered with the O-ring 2.
4, the toner does not enter the inner diameter portion 26 and does not leak from the outside of the outer diameter portion 27.

[0007]

The bearing 21 with the seal function having the above structure has satisfactory sealing function and bearing function. However, three parts, namely, the bearing body 22, the rubber seal 23 and the O-ring 24 are assembled. Due to the configuration, time and labor are required for assembly, and in addition, the cost of parts, especially the rubber seal 23, is large, and there are problems in both production and cost. Therefore, the rubber seal 23
Although the material was changed and the assembling work was improved, it was not satisfactory due to structural limitations, and on the contrary, there was a problem that sealing performance was lowered.

The present invention has been made in view of these problems, and has a sealing function and a bearing function equivalent to those of a conventional bearing incorporating a rubber seal or an O-ring, and is provided with a sealing function which is excellent in productivity and in price. It is intended to provide a bearing.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention relating to a bearing with a sealing function is provided by an elastomeric cylindrical bearing having an outer peripheral surface mounted on a housing and an inner peripheral surface supporting a rotating shaft. And an annular lip protruding radially inward from one end of the inner peripheral surface and abutting on the outer peripheral surface of the rotating shaft is formed integrally with the cylindrical bearing ( Claim 1). Here, the “one end side” described in the present specification is a concept that includes a case where it is adjacent to one end of the inner peripheral surface and a case where it is separated from one end of the inner peripheral surface. This also includes the case where a larger-diameter cylindrical inner circumferential surface space is formed and a lip portion is formed in any of the spaces. According to this means, the lip portion comes into contact with the outer peripheral surface of the rotary shaft, and the space on both sides of the lip portion can be shielded. Therefore, by arranging the bearing having the sealing function with the lip side facing the region where the fine powder such as toner is interposed, it is possible to prevent toner and the like from entering the inner peripheral surface. In other words, the bearing with a sealing function is such that a sealing mechanism for the inner peripheral surface, such as a conventional rubber seal, is integrally formed. Is unnecessary.

When the lip portion is inclined in the axial direction (claim 2), the elastic lip portion obliquely contacts the rotating shaft while pressing the rotating shaft with a predetermined elasticity. Prevention of intrusion of fine powder can be more complete.

Furthermore, when the circumferentially extending annular ridge is integrally formed on the outer peripheral surface of the bearing with the sealing function (claim 3), the bearing with the sealing function is formed in a housing or the like as described above. When fitted into the opening, the convex portion of the means has a function of sealing a gap with the opening.
In other words, the conventional fitting surface between the bearing and the opening requires O
Since the ring is integrally formed, the O-ring mounting operation required for the conventional bearing can be omitted.

As a material for the above-mentioned bearing with a sealing function, J
It is preferable to use a thermoplastic elastomer having an IS-A hardness of 70 to 90 or a composition containing a thermoplastic elastomer having a JIS-A hardness of 70 to 90 (claim 4).
Here, the “JIS-A hardness” described in the present specification is:
It means the hardness by the spring hardness test (A type) specified in JIS. If the hardness is less than 70, the sliding resistance between the bearing and the shaft increases, so that the toner and the like are melted by frictional heat, which further increases the sliding resistance. On the other hand, if the hardness exceeds 90, the force of tightening the shaft by the lip portion increases, and as a result, the lip portion is easily worn, that is, the sealing function is easily reduced.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings as appropriate. FIGS. 1A and 1B are schematic cross-sectional views showing a bearing with a seal function according to an embodiment of the present invention, and FIGS. 2A and 2B are FIGS.
It is a typical sectional view showing a bearing with a seal function concerning a form different from a bearing with a seal function of.

A bearing 1 with a seal function shown in FIG. 1A has an inner peripheral surface 2 in the form of a cylindrical inner peripheral surface for supporting a cylindrical rotary shaft, similarly to a normal bearing, and additionally has an annular lip portion. 3 is equipped with one. The lip portion 3 is protruded from one end of the inner peripheral surface 2 inward in the radial direction and inclined in the direction of the inner peripheral surface 2. In other words, the lip portion 3 is formed in the shape of a peripheral wall of a truncated hollow cone. The shape of the lip portion 3 is reduced in thickness from the root side to the tip (inner diameter end) side, that is, the cross-sectional shape is formed at an acute angle. The lip portion 3 having the above structure comes into contact with the peripheral surface of the fitted rotating shaft while applying a pressing force. Therefore, when fine powder such as toner is present on the side on which the lip portion 3 is provided on both sides of the bearing 1 with the seal function, the lip portion 3 can prevent the fine powder from entering the inner peripheral surface 2. . Therefore, as described above, a rubber seal or the like which is necessary for the conventional bearing to prevent the intrusion of the fine powder such as the toner becomes unnecessary.

As a material of the bearing 1 with a sealing function,
Thermoplastic elastomer is used, for example, styrene,
Olefin, ester, urethane, amide, N
Although there is no particular limitation such as BR type and fluorine type, those having a JIS-A hardness (hereinafter simply referred to as “hardness”) of 70 to 90 are suitable. If the hardness is less than the above range, the sliding resistance on the inner peripheral surface 2 increases, so that the toner is melted by frictional heat, and the sliding resistance further increases. If it exceeds the range, the lip 3
This is because the force for tightening the rotating shaft is increased, so that the lip portion 3 is easily worn, and the sealing function is easily reduced.

In the case of a thermoplastic elastomer having a hardness not in the above range, a general-purpose thermoplastic resin is added to adjust the hardness to the above range, so that it can be used as a material of the bearing 1 with a sealing function. For example, a) in the case of a styrene-based thermoplastic elastomer having a hardness of 40, adding an acrylonitrile-butylene-styrene copolymer;
b) In the case of an ester-based thermoplastic elastomer having a hardness of more than 90, an amorphous polyester having a hardness of 40 is added. c) In the case of a fluorine-based thermoplastic elastomer having a hardness of less than 70, tetrafluoroethylene-perfluoroalkyl is used. The hardness can be adjusted to the above range by adding a vinyl ether copolymer or an ethylene tetrafluoroethylene copolymer.

Injection molding is suitable as a method for producing the bearing 1 with a sealing function. The material can be easily molded by injection molding into a mold. Molding means other than such injection molding, such as vulcanization molding of rubber or cast molding of urethane, is also possible, but requires a plurality of steps, and is therefore less economical than injection molding.

The bearing 4 with a sealing function shown in FIG. 1B is different from the bearing with a sealing function shown in FIG. 1A in that a lip portion 6 is integrally formed at one end of an inner peripheral surface 5 for supporting a rotating shaft. It is the same as the bearing 1. However, the lip portion 6 is inclined such that its tip is separated from the inner peripheral surface 2 of the bearing 4 with a sealing function. Therefore, the lip 6
When the bearing 4 with the sealing function is disposed so as to face
The tip of the lip 6 is inclined in the toner interposition direction.
The effect of preventing the intrusion of the toner is higher when the lip portion 6 is inclined toward the side from which the toner comes.

The bearing 7 with a seal function shown in FIG. 2 has a lip 9 integrally formed at one end of an inner peripheral surface 8 as shown in FIG.
It is the same as the bearings 1 and 4 with the sealing function of (a) and (b), and is the same as the bearing 4 with the sealing function of FIG. 1B in that the lip 9 is inclined so as to protrude outward. is there.
However, the bearing 7 with a sealing function is a cylindrical outer peripheral surface 1.
1, a ridge 10 is integrally formed. This ridge 1
Numeral 0 protrudes in a semicircular cross section and is continuous for one round in the circumferential direction. Since the elastomer material having a hardness of 70 or more and 90 or less used for the bearing with a seal function 7 is relatively easily deformed, even if the elastomer material is fitted and attached to the mounting opening, it is deformed along the opening and the gap is formed. Does not occur. Therefore, although there is an effect of preventing toner leakage without using an O-ring, which is necessary for a conventional bearing, the ridge portion 1 which functions as an O-ring like the bearing 7 with a sealing function is provided.
By forming 0 integrally, the integrity of the toner leakage prevention effect can be enhanced.

[0020]

Hereinafter, the present invention will be described in detail with reference to Examples.
Of course, the present invention should not be construed as being limited based on the description of this embodiment.

Example 1 A bearing having a seal function of Example 1 was obtained by injection molding a urethane-based thermoplastic elastomer having a JIS-A hardness of 70 (trade name “Rezamin P-4585” manufactured by Dainichi Seika Co., Ltd.). Was. This bearing with a sealing function is the same as the bearing with a sealing function 12 shown in FIG. 3 and has a lip on one end side of the inner peripheral surface, and the tip of the lip is inclined so as to project outward. Things.

[Examples 2 to 10] The hardness was 75,
Except for using 79, 80, 84, 85, 86, 87, 88, and 90, the same procedure as in Example 1 was performed to obtain bearings with seal functions of Examples 2 to 10.

Reference Example A polyacetal (trade name "Duracon AW-01" manufactured by Polyplastics Co., Ltd.) is formed into a round bar by an extruder, and this is cut to obtain a substantially cylindrical bearing body. An NBR rubber seal (manufactured by NOK) having a lip is attached to one end of the inner peripheral surface of the bearing body, and an O-ring (manufactured by NTN) is further provided on the outer peripheral surface of the bearing body.
To obtain a bearing of Comparative Example 1 similar to the bearing 21 shown in FIG.

[Comparative Examples 1 to 6] Hardness was 58 and 6 respectively.
Except for 0, 65, 93, 95, and 98, the same procedures as in Example 1 were performed to obtain bearings with seal functions of Comparative Examples 1 to 6.

[Evaluation of Characteristics] Using the bearings with a seal function of Examples 1 to 10, Reference Example and Comparative Examples 1 to 6, an experiment was conducted to evaluate the toner sealability and the torque of the rotating shaft. As shown in FIG. 3, the apparatus used in this experiment fits a pair of bearings 12 with a seal function on both ends of a cylindrical toner box 14 so that the lip portions 13 of the bearings are paired with each other.
One cylindrical stainless steel rotary shaft 15 is supported by the pair of bearings 12 having a seal function. This rotating shaft 15
Has a motor 16 connected to one end thereof and a torque meter 1 connected to the other end.
7, and a stirring screw 18 for stirring the toner was provided on the outer peripheral portion. Further, the inside of the toner box 14 was filled with toner.

The bearings with seal function of the above-mentioned Examples 1 to 10, Reference Example and Comparative Examples 1 to 6 are used as the bearing with seal function 12 of the above apparatus, and the rotation speed of the rotating shaft 15 is continuously set to 400 rpm. Operation was performed and the following measurements were performed. First, the time until the toner leaked from the bearing 12 with the seal function was measured, and the toner sealability was evaluated. Here, the evaluation of the toner sealability was based on the time until the toner leaked was 80 hours.
The case where the time was less than 0 hours was evaluated as x. Also, after starting operation, 2
The torque of the rotating shaft after 0 hour, 40 hours, 80 hours, and 100 hours was measured by the torque meter 17 and evaluated. Here, as the evaluation of the torque, the torque was 200 gf · cm.
基準, 200 if less than 200 gf · cm
The case of gf · cm or more was evaluated as x. These results are shown in Table 1 for Examples and Table 2 for Reference Examples and Comparative Examples.
Shown in

[0027]

[Table 1]

[0028]

[Table 2]

As shown in Table 1, the bearings with a sealing function of Examples 1 to 10 have good toner sealing properties and do not require a rubber seal or an O-ring as in the reference example. Further, the torques of the bearings with seal functions of Examples 1 to 10 are sufficiently small, and are values that can be sufficiently used as bearings. On the other hand, as shown in Table 2, the bearings with a sealing function of Comparative Examples 1 to 6 have poor toner sealing properties, and do not need rubber seals or O-rings as in the reference example. Furthermore, the bearings with a seal function of Comparative Examples 1 to 3 have a large torque and are not suitable as bearings. Further, it was found that the use of expensive components can be eliminated as compared with the reference example, and the number of assembly steps can be significantly reduced.

[0030]

As described above, in the bearing with the seal function of the present invention, the sealing performance of the rubber seal or the O-ring and the bearing performance of the oilless resin bearing are integrally formed by the elastomer having the JIS-A hardness of 70 to 90. As a result, the number of assembly steps can be reduced, the cost can be reduced, and the productivity can be improved.

[Brief description of the drawings]

FIG. 1A is a schematic cross-sectional view showing a bearing with a sealing function according to an embodiment of the present invention, and FIG. 1B is a bearing with a sealing function according to a different form from the bearing with a sealing function in FIG. FIG.

FIG. 2 is a schematic sectional view showing a bearing with a sealing function according to a different form from the bearing with a sealing function in FIGS. 1 (a) and 1 (b).

FIG. 3 is a schematic cross-sectional view showing an experimental device of an example.

FIG. 4 is a schematic sectional view showing a conventional bearing with a sealing function.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bearing with a sealing function 2 Inner peripheral surface 3 Rip part 4 Bearing with a sealing function 5 Inner peripheral surface 6 Rip part 7 Bearing with a sealing function 8 Inner peripheral surface 9 Rip part 10 Convex part 11 Outer peripheral surface 12 Bearing with a sealing function 13 Lip Unit 14 Toner box 15 Rotary shaft 16 Motor 17 Torque meter 18 Stirring screw

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 2H077 AD06 CA13 FA22 3J016 AA02 BB03 3J043 AA16 BA05 CA02 CB13 CB14 DA11 FB20

Claims (4)

[Claims] 1. An elastomeric cylindrical bearing having an outer peripheral surface mounted on a housing and an inner peripheral surface for supporting a rotating shaft, protruding radially inward from one end of the inner peripheral surface and rotating. A bearing with a seal function, wherein an annular lip portion abutting on the outer peripheral surface of the shaft is formed integrally with the cylindrical bearing. 2. The bearing with a sealing function according to claim 1, wherein the lip portion is inclined in the axial direction. 3. The bearing with a sealing function according to claim 1, wherein the annularly extending ridge extending in the circumferential direction of the outer peripheral surface is formed integrally. 4. The composition according to claim 1, wherein the composition comprises a thermoplastic elastomer having a JIS-A hardness of 70 to 90 or a composition containing a thermoplastic elastomer having a JIS-A hardness of 70 to 90. Bearing with seal function.