JPH07139541A - Rubber roller and manufacture thereof - Google Patents

Abstract

PURPOSE:To make the surface condition favorable and improve contact performance with the other roller and the like by forming the boundary part between small diameter shaft parts formed on both end parts of a shaft body and the other part into taper parts, and forming a rubber elastic body layer part on them into nearly same shape. CONSTITUTION:As for the shaft body 1 of a rubber roller, the shaft body of which both ends are formed into small diameter shaft parts, and the boundary part between the small diameter shaft part and the other part is formed into a taper part, is used. The shaft body 1 is fixed with a metal mold fixing member 10 so as to be positined inside a metal mold. Further, the shaft body 1 is previously spread with adhesive 8 on the part on which a rubber elastic body layer 2 is formed. By filling unvulcanized rubber composite in the gap between the shaft body 1 and the metal mold 9, heating, vulcanizin, and drawing the mold, the rubber elastic body layer 2 part is formed into a taper shape because the rubber elastic body layer 2 is shrunk along the form of the shaft body 1 by vulcanization, and the rubber roller can be manufactured without executing a postwork such as polishing of the surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber roller used in office automation equipment such as printers and electrophotographic copying machines, and a method for producing the rubber roller.

[0002]

2. Description of the Related Art Conventionally, a rubber roller having a rubber elastic layer formed on the outer periphery of a shaft has been widely used as a component of the OA equipment. For example, in an electrophotographic copying machine, a developing roller that supplies toner to the surface of the photosensitive drum,
Examples of the fixing roller include a fixing roller for fixing the toner under pressure, a pressure roller, and a paper feeding roller. These rubber rollers are used while being in pressure contact with each other or with other rollers or members having a metal surface or a resin surface. For example, in the fixing roller and the pressure roller, as shown in FIG. 10, both ends of the shaft portion of the fixing roller 15 are fixed, and both ends of the shaft portion of the pressure roller 14 are loaded with springs or the like, It is used by rotating the roller in a state of being pressed against it. The above-mentioned paper feed roller is also used in the same manner. In the developing roller, the layer forming member is brought into pressure contact with the developing roller to generate friction. However, there is a problem in that the rubber roller is floated or bent due to the use in such a pressed state. That is, in the fixing roller and the pressure roller shown in FIG. 10, since a load is applied to both ends of the shaft portion to bring them into pressure contact with each other, the rubber roller central portion 6 bends as shown in FIG. For this reason, there arises a problem that the contact state of both rollers is deteriorated at this portion and the image quality of the copied image is deteriorated.

[0003]

In order to solve the problem of floating and bending, the rubber elastic layer 5a is gradually changed from the end to the center as shown in FIG. 11 (B). It has been proposed and partially implemented to make a so-called crown shape that rises up. With such a shape, even if a large load is applied and the rubber roller is pressed against the rubber roller, floating or the like does not occur. This crown-shaped rubber elastic body layer is formed by first forming a cylindrical rubber elastic body layer 5 on the outer periphery of the shaft body 4 as shown in FIG. It is produced by However, this method has a problem that the manufacturing process is lengthened and the cost is increased because the rubber roller is further processed after being manufactured. Further, there is also a problem in that the surface condition of the rubber roller deteriorates when subjected to processing such as polishing. Therefore, it is difficult to apply this method to a fixing roller, a developing roller, or the like that requires the surface of the rubber elastic layer to have a mirror-finished surface with Ra of 0.5 or less. Further, a resin layer or the like may be further formed on the surface of the rubber roller to add new characteristics. At this time, if the surface of the rubber elastic layer that is the base is rough, this effect appears in the roller surface layer. On the other hand, as another method of forming the rubber elastic layer into a crown shape, as shown in FIG.
As shown in FIG. 1 (C), there is a method of forming a coating layer 7 by coating a coating material or the like on the outer periphery of the rubber elastic layer 5b while changing the thickness. In this case, in order to make the contactability of the rubber roller sufficient, it is necessary to thicken the central portion of the coating layer 7. However, in order to do so, it is necessary to increase the coating amount of the coating material, which causes problems such as an increase in cost and workability due to dripping during the coating operation. As described above, in the conventional method, when trying to solve the problem such as floating of the rubber roller, other problems such as deterioration of the surface state of the rubber elastic layer occur. Therefore, it is strongly desired to develop a technique that completely solves the problems such as floating without causing other problems.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a low cost rubber roller having a good surface condition and excellent contact with other rollers and a method for producing the same. To do.

[0005]

In order to achieve the above object, the present invention is a rubber roller having a rubber elastic layer formed on the outer periphery of a shaft body, wherein both ends of the shaft body have a small diameter shaft. And a boundary portion between the small-diameter shaft portion and the other portion is formed into a tapered portion, and the rubber elastic layer portion corresponding to the tapered portion is formed into a tapered shape substantially similar to the above. A method of manufacturing a rubber roller in which a rubber elastic layer is formed on the outer periphery of a shaft body, in which both ends are formed into a thin shaft portion, and Prepare a shaft body in which the boundary part with the part is formed in a taper part, place this shaft body in a mold having a cylindrical inner peripheral mold surface, and leave a gap between the shaft body and the mold surface. The unvulcanized rubber composition is introduced into the vulcanizate, which is vulcanized to form a rubber elastic layer on the outer periphery of the shaft, and then The the method of demolding for the rubber roller and the second aspect.

[0006]

In other words, the present inventors have conducted a series of researches centering on the method for forming the rubber elastic layer in order to solve the problems such as floating of the rubber roller without causing other problems. In the process of this research, I got the idea to utilize the vulcanization shrinkage of rubber. That is, as the shaft body, use is made of a shaft body in which both ends are formed in a small-diameter shaft portion, and a boundary portion between the small-diameter shaft portion and other portions is formed in a tapered portion, and the shaft body is formed into a cylindrical shape. It is a manufacturing method in which the unvulcanized rubber composition is placed in a mold having an inner peripheral mold surface, the unvulcanized rubber composition is introduced into a gap between the shaft body and the mold surface, and vulcanized. As a result, it was found that the rubber elastic body layer contracts along the shape of the shaft body due to the vulcanization, so that the portion of the rubber elastic body layer corresponding to the tapered portion of the shaft body is also formed in a tapered shape. Arrived According to the present invention, a rubber roller as shown in FIG. 1 can be manufactured at low cost without performing post-processing such as polishing. In the figure, 1 is a shaft, and 2 is a rubber elastic layer.

Next, the present invention will be described in detail.

The rubber roller of the present invention can be produced, for example, by using a shaft and an unvulcanized rubber composition as a material and using a mold having a cylindrical inner peripheral mold surface.

As shown in FIG. 2, both ends of the rubber roller shaft are formed in a small-diameter shaft portion 1b. The small-diameter shaft portion 1b and the other portion (large-diameter shaft portion) 1a are formed. It is necessary to use the one in which the boundary portion is formed in the tapered portion 1c. Usually, the inclination ratio of the tapered portion 1c is the ratio of the difference between the diameter (b) of the small diameter shaft portion 1b and the diameter (a) of the large diameter shaft portion 1a with respect to the length (L) of the tapered portion 1c [(a-
b) / L]. The inclination ratio of the taper portion 1c of the shaft body 1 used in the present invention is appropriately determined depending on the type of the rubber roller, the place where it is used, etc.
b) /L=0.01 to 1, preferably 0.015
The range is from 0.15 to 0.15. The size of the shaft body 1 is also appropriately determined depending on the type of rubber roller and the like, but the length of the entire shaft body is 180 to 500 mm, preferably 220 to 4 mm.
50 mm, the length of the small-diameter shaft portion 1b is 100 mm or less, preferably 10 to 20 mm, and the diameter (b) of the small-diameter shaft portion 1b is 3 to
20 mm, preferably 6 to 10 mm, and the large diameter shaft portion 1a diameter (a) is set to 3.5 to 22 mm, preferably 7 to 11 mm.

The material for forming the shaft is not particularly limited, and examples thereof include stainless steel generally used as the shaft of the roller.

The unvulcanized rubber composition, which is a material for forming the rubber elastic layer of the rubber roller, can be obtained by blending a rubber component as a base material with an additive such as a vulcanizing agent.

As the above-mentioned rubber component, those used for ordinary rubber rollers are used, for example, ethylene-propylene rubber, styrene-butadiene rubber (SBR),
Examples include synthetic rubber and natural rubber such as silicone rubber, urethane rubber, nitrile rubber, butadiene rubber, hydrin rubber, acrylic rubber, norbornene polymer. Among these, it is preferable to use SBR.

As the vulcanizing agent, a general rubber vulcanizing agent is used, and examples thereof include sulfur, organic sulfur compounds, metal oxides and peroxides. Among these, it is preferable to use sulfur.

Then, the above-mentioned vulcanizing agent and, if necessary, a rubber additive such as a vulcanization accelerator and a filler are mixed with a rubber component, and these are kneaded with a roll, a kneader or the like to obtain an unvulcanized rubber. The composition can be prepared.

Next, the rubber roller of the present invention can be manufactured by using the above shaft and the unvulcanized rubber composition, for example, as shown below.

That is, first, a mold having a cylindrical inner peripheral mold surface is prepared. The mold may be a pipe shape. Further, it is preferable that the inner peripheral surface of the mold is mirror finished by honing or the like. By using such a mold, the surface of the rubber elastic layer of the obtained rubber roller becomes a mirror surface. Therefore,
It also becomes possible to manufacture a fixing roller, a developing roller and the like which require a high degree of surface condition.

Then, as shown in FIG. 3, the shaft 1 is fixed to the mold fixing member 10 so that the shaft 1 is located inside the mold 9. It is preferable to use the mold fixing member 10 that can prevent the shaft body 1 from extending in the longitudinal direction due to heating during vulcanization. Further, it is preferable that the shaft body 1 and the mold 9 are fixed such that the shaft deflection (coaxiality) is 0.2 mm or less. That is, if the runout exceeds 0.2 mm, the rotatability of the rubber roller obtained will deteriorate.

Further, it is preferable that the shaft body 1 is coated with the adhesive 8 in advance on the portion where the rubber elastic layer is formed. The adhesive is not particularly limited, and includes phenol resin type, chlorinated rubber type, elastomer type,
Examples include coupling (organosiloxane-based) agents.

Then, the unvulcanized rubber composition 2a is filled in the gap between the shaft body 1 and the mold 9. The thickness of the unvulcanized rubber composition 2a layer formed at this time is not uniform, and gradually increases from the large diameter shaft portion 1a toward the small diameter shaft portion 1b along the taper portion 1c. . Then, the unvulcanized rubber composition 2a is heated and vulcanized, and by demolding it,
As shown in FIG. 1, a portion of the rubber elastic body layer 2 corresponding to the tapered portion 1c of the shaft body 1 is formed in a tapered shape substantially similar to the above. This is because the vulcanization shrinkage of rubber occurs in proportion to the thickness of the unvulcanized rubber composition 2a layer. That is,
In the present invention, as described above, the unvulcanized rubber composition 2a
The thickness of the layer is not uniform and gradually increases from the large-diameter shaft portion 1a toward the small-diameter shaft portion 1b along the tapered portion 1c. Therefore, vulcanization shrinkage also occurs according to the wall thickness, and as a result, the rubber elastic layer portion corresponding to the tapered portion 1c of the shaft body is tapered. As described above, in the present invention, both ends of the rubber elastic layer can be formed in a taper shape at the same time as the rubber is vulcanized, so that it is not necessary to make the taper shape by post-processing such as polishing. This is one of the features of the present invention. Further, in the present invention, for example, the mirror surface of the inner peripheral surface of the mold is directly transferred to the surface of the rubber elastic body layer 2. Therefore, it is possible to obtain a rubber elastic layer having a mirror finish. This is also a feature of the present invention.

In the rubber roller, as shown in FIG. 4, both ends 11 of the rubber elastic layer 2 may jump up to release the stress. With such a shape, the contactability with other rollers and the like may decrease. Therefore, as a means for solving this, as shown in FIG. 5, a ring 12 such as a Teflon tube is attached to the boundary between the tapered portion 1c of the shaft body 1 and the small-diameter shaft portion 1b, and then the unvulcanized rubber composition 2a. Can be vulcanized and the ring 12 can be removed. By this method, as shown in FIG. 6, the space 1 is formed at both ends of the rubber elastic layer.
3 is formed to have a lightened shape, the hardness of the end portion of the rubber elastic body layer is artificially reduced, and the problem of contact is solved.

[0021]

As described above, according to the manufacturing method of the present invention, both end portions are formed in the small diameter shaft portion, and the boundary portion between the small diameter shaft portion and the other portion is formed in the tapered portion. Using a body, this shaft is placed in a mold having a cylindrical inner peripheral mold surface, and an unvulcanized rubber composition is introduced into the gap between the shaft and the mold, and when vulcanizing this The heat-shrinkage is used to form a rubber elastic layer having a shape along the outer peripheral shape of the shaft body. Therefore, it becomes possible to automatically manufacture a rubber roller whose both ends have a small diameter. As described above, in the method for manufacturing the rubber roller of the present invention, it is not necessary to process both ends into a small diameter by post-processing such as polishing after forming the rubber elastic layer, so that the process is simplified and the production efficiency is improved. .
Further, in the present invention, by using a mold whose inner peripheral surface is a mirror surface as a mold used for molding, the surface of the rubber elastic layer can be mirror-finished. Therefore, it is most suitable for manufacturing a fixing roller, a developing roller and the like which require a high mirror surface condition. Further, the rubber roller of the present invention has a shape in which the rubber elastic layer has a thicker central portion than both end portions, so that it has excellent contactability with other rollers and the like, and increases the pressure contact load. Even if it does not float. That is, when the rubber roller of the present invention is used as, for example, a fixing roller, the contact property with the pressure roller becomes excellent, and the fixing of the toner becomes uniform, and the obtained copy image has a high image quality. Further, in a rubber roller having a hard rubber elastic layer having a hardness of around 40 (JIS A), conventionally, it was necessary to set the runout (coaxiality) to 0.06 mm or less, but the rubber roller of the present invention Then, the shake standard can be expanded to around 0.15 mm.

Next, examples will be described together with comparative examples.

[0023]

[Example 1] Diameter of small diameter shaft portion (b) 6 mm, diameter of large diameter shaft portion (a) 8 mm, length of tapered portion (L) 30 mm
A shaft body of [(ab) /L=0.067] was prepared. On the other hand, 100 parts by weight of rubber component (SBR) [abbreviated as "part" below) and 2 parts of vulcanizing agent (sulfur), carbon black, paraffin oil, and vulcanization accelerator as additives are blended to obtain unvulcanized A rubber composition was prepared. Then, as shown in FIG. 3, the shaft 1 and the mold 9 having the cylindrical inner peripheral mold surface were mounted on the mold fixing and supporting member 10 and filled with the unvulcanized rubber composition 2a. Then, it was heated and vulcanized at a temperature of 150 ° C. for 60 minutes and then demolded to produce a rubber roller having a rubber elastic layer hardness of 37 (JIS A). The maximum thickness of the rubber elastic layer was 5 mm, and the mold 9 used had a mirror-finished inner peripheral surface.

[0024]

[Example 2] As a shaft body, the diameter (b) of the small-diameter shaft portion was 6 m.
m, the diameter (a) of the large diameter shaft portion was 10 mm, and the length (L) of the taper portion was 30 mm [(ab) /L=0.133]. A rubber roller was produced in the same manner as in Example 1 except for the above.

In the rubber rollers of Examples 1 and 2 thus obtained, the surface of the rubber elastic layer was a mirror surface. Then, the shapes of the rubber elastic layers of the rubber rollers of these example products 1 and 2 are laser-scanned (LSM-161).
0, manufactured by Mitutoyo). The result is shown in the graph of FIG. In this graph, the solid line represents the rubber roller of Example product 1, and the dotted line represents the rubber roller of Example product 2. The measured value with this laser scan is 10
It is the average of two measurements. From the graph of FIG. 7, it can be seen that in both the rubber rollers of Examples 1 and 2, both end portions of the rubber elastic body layer are tapered along the tapered portion of the shaft body.

[0026]

Comparative Example An ordinary shaft body having a diameter of 10 mm and having no tapered portion was used. A rubber roller as shown in FIG. 11A was manufactured by the same method as in Example 1 except for this.

Using the rubber roller of this comparative example product and the rubber roller of the above-mentioned example product 1, the relationship between the amount of pressure gap and the runout was examined. The result is shown in the graph of FIG. In this graph, the solid line represents the rubber roller of Example product 1 and the dotted line represents the rubber roller of Comparative example product. The above relationship is
It investigated by the following method.

[Relationship between Pressurization Gap Amount and Runout] The relationship between the pressurization gap amount and runout was examined as shown in FIG. That is, the metal facing polishing roller 17 and the evaluation target roller 1
6 was placed in contact. Then, a load was applied from the direction of the arrow to rotate the rollers 16 and 17. 20 is a motor for rotating the roller. Then, at this time, the contact portion between the rollers 16 and 17 was irradiated with a light 18 and observed with a charge-coupled device (CCD) camera to examine the amount of pressure gap. The runout accuracy of the evaluation target roller at this time was previously confirmed using the laser scan.

From the graph of FIG. 8, the rubber roller of Example 1 did not cause floating due to pressure even when the runout was 0.2 mm. On the other hand, in the rubber roller of the comparative example product, floating occurred when the shake was 0.1 mm or less.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a rubber roller of the present invention.

FIG. 2 is an explanatory view of an end portion of a shaft body used in the rubber roller of the present invention.

FIG. 3 is an explanatory view showing a method for manufacturing a rubber roller of the present invention.

FIG. 4 is an explanatory diagram showing a state where both end portions of the rubber elastic layer are jumped up by releasing stress.

FIG. 5 is an explanatory view showing a state in which a ring is attached to the shaft body to form a rubber elastic body layer.

FIG. 6 is an explanatory view showing a state where both ends of the rubber elastic layer are formed by thinning.

FIG. 7 is a graph in which the shape of a rubber elastic body layer is examined by laser scanning.

FIG. 8 is a graph showing the relationship between the amount of pressurizing gap and runout.

FIG. 9 is an explanatory diagram showing a method for measuring the relationship between the amount of pressurization gap and the shake.

FIG. 10 is an explanatory diagram showing a state in which two sets of rubber rollers face each other and are in contact with each other.

11A is a cross-sectional view of a conventional rubber roller, FIG. 11B is a cross-sectional view of a rubber roller having a conventional rubber elastic layer having a crown shape, and FIG. It is sectional drawing of the changed conventional rubber roller.

[Explanation of symbols]

 1 Shaft 2 Rubber elastic layer

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Claims (2)

[Claims] 1. A rubber roller having a rubber elastic layer formed on the outer periphery of a shaft body, wherein both ends of the shaft body are formed into a small-diameter shaft portion, and the small-diameter shaft portion and other portions are formed. Is formed in a tapered portion, and the rubber elastic layer portion corresponding to the tapered portion is formed in a taper shape substantially similar to the above. 2. A method of manufacturing a rubber roller in which a rubber elastic layer is formed on the outer periphery of a shaft body, wherein both ends are formed into a small diameter shaft portion, and the boundary between the small diameter shaft portion and other portions. A shaft body having a tapered portion is prepared, the shaft body is placed in a mold having a cylindrical inner peripheral mold surface, and unvulcanized rubber is placed in a gap between the shaft body and the mold surface. A method for producing a rubber roller, which comprises introducing a composition, vulcanizing the composition to form a rubber elastic body layer on an outer periphery of a shaft, and then demolding the rubber elastic body layer.