JPH05119654A - Roll for fixing device - Google Patents

Abstract

PURPOSE:To obtain a roll for a fixing device which can prevent the degradation in friction force by assuring prescribed elastic force uniformly in the longitudinal direction of the roll. CONSTITUTION:Rubber layer 3 are provided at the end in the axial direction of a sponge layer 2 of the roll for the fixing device having a surface coating layer 5 via the sponge layer 2 around a shaft-shaped arbor 1 and plural through- holes 4 extending in the axial direction are formed through the rubber layers 3 and the sponge layer 3 around the arbor 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device roll for fixing an unfixed image as a permanent image on a recording material such as paper, which is used in a copying machine, a printer or the like to which electrophotography is applied.

[0002]

2. Description of the Related Art In recent years, in copying machines, printers and the like to which electrophotography is applied, the fixing rolls used in the fixing device have been made smaller and lighter as the size and weight have been reduced. For example, as shown in FIGS. 5 and 6 of the accompanying drawings, a sponge layer 12 is formed around a shaft-shaped core metal 11,
A roll is known in which a surface coating layer 15 is formed on the outer periphery of the sponge layer, and a plurality of straight through holes 14 or spiral through holes are formed in the sponge layer in parallel with the longitudinal direction of the core metal (Japanese Patent Laid-Open No. Hei 10 (1999) -31977). 2-282833).

[0003]

However, in the conventional fixing roll having the above-mentioned structure, the end portion is deformed with a higher degree of freedom than the central portion, so that the elasticity at the end portion is in the central portion. It tends to be slightly lower than that. Further, paper powder and other dusts intrude from the end of the sponge due to long-term paper feeding, and the elasticity of the sponge layer deteriorates, and the elasticity of the end further deteriorates. Furthermore, the natural elasticity of the unvulcanized component of the material forming the sponge due to long-term use deteriorates the elasticity of the sponge layer, resulting in a decrease in the elasticity of the ends. As a result, there is a drawback that the fixing property at the end portion is inferior to that at the central portion. In addition to this, when the above roll is used as a roll which is driven by being in contact with a roll transmitting a driving force and receiving a frictional force, the roll is pressed against the roll transmitting the driving force because the roll itself is soft. It is not possible to reduce the frictional force. Further, since the fixing roll has a material on the surface that improves the releasability of the transfer material,
This also reduces the frictional force. As a result, when the load on the fixing roll during rotation increases, the roll will not rotate.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a fixing device roll capable of uniformly securing a predetermined elastic force in the lengthwise direction of the roll and preventing a decrease in frictional force. ..

[0005]

According to the present invention, the above object is to provide a fixing device roll having a surface coating layer around a shaft-shaped core metal with a sponge layer interposed therebetween. This is achieved by providing a rubber layer on the core metal and forming a plurality of through holes extending in the axial direction through the rubber layer and the sponge layer around the core metal.

[0006]

In the present invention having the above-mentioned structure, the roll itself is reinforced at the end portion as compared with the central portion to have high elasticity. Therefore, when it comes into contact with the driving roll, the end portion, which is originally liable to be deformed, is not so much deformed, and is substantially the same as the central portion, that is, the entire roll is uniformly deformed in its longitudinal direction. Therefore, the frictional force is not reduced. In addition, the rubber layer prevents dust and foreign matter from entering the sponge portion from the outside. Further, as a result, deterioration of the sponge layer due to long-term use is prevented, and the uniform deformation is maintained.

[0007]

Embodiments of the present invention will now be described with reference to FIGS. 1 to 4 of the accompanying drawings. FIG. 1 is a sectional view of a fixing roll as a first embodiment of the present invention, and FIG. 2 is a side view thereof.

In the figure, reference numeral 1 denotes a mandrel which forms a shaft, and is relatively thick around the sponge layer 2 except a predetermined range at both ends thereof.
Are formed. Rubber layers 3 are provided on both outer sides of the sponge layer 2. The rubber layer 3 may be adhered to the sponge layer 2 or may be integrally molded with the sponge layer 2. The rubber layer 3 is formed of a material that is less likely to be deformed and has greater elasticity than the sponge layer 2. The rubber layer 3 can also be formed by suppressing foaming at both ends of the sponge layer 2.

A plurality of through holes 4 extending in the longitudinal direction of the core metal 1 are formed in the sponge layer 2 and the rubber layer 3 around the core metal 1. The through hole 4 may extend linearly or may have a spiral shape, for example. The sponge layer 3 is set to be wider than the maximum paper passing width of the fixing device in the longitudinal direction of the core metal 1, and the rubber layer 3 is located in the non-paper passing portion. This is to avoid wrinkles on the transfer paper when there is a portion with different elasticity in the paper passing portion, and this is to be avoided.

A surface coating layer 5 is uniformly formed on the surfaces of the sponge layer 2 and the rubber layer 3. The roll for the fixing device having such a structure was incorporated in a copying machine having a copying speed of 30 CPM, and a paper passing experiment was conducted.

When the rolls for the conventional fixing device shown in FIG. 5 and FIG. 6 are used, the roll sagging occurs after 5,000 sheets have passed, and from about 10,000 sheets, at the end of the maximum sheet passing width. A decrease in fixability was observed. However, when the roll for the fixing device of this example was used, the fixing property was not deteriorated even when 30,000 sheets were passed.

The sagging at the end of the conventional fixing device roll is
First, the silicone oil applied to the fixing roll permeated from the end of the sponge layer and was deformed as shown in FIG.

Next, a second embodiment of the present invention will be described. FIG. 3 is a sectional view of the fixing roll of this embodiment. In addition,
In the figure, the same parts as those of the previous embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the surface coating layer 5 is formed only in the area of the sponge layer 2. Therefore, the rubber layer 3
The outer diameter of the portion is set to be the same as or slightly smaller than the outer diameter of the sponge layer 2 including the surface coating layer 5. This value is set so that the contact portion between the fixing roll and the pressure roll, that is, the so-called nip portion is uniform.

A sheet passing experiment similar to that of the first embodiment was conducted on the fixing device roll of the present embodiment having the above-mentioned structure. As a result, as in the case of the first embodiment, even after passing 30,000 sheets, good fixing property is exhibited, and slip caused by a reduction in friction with the fixing roller caused by paper dust generated during the paper feeding experiment. Also did not occur. It is considered that this is because the rubber layer 3 provided at the end of the fixing roller maintains friction with the fixing roller.

Next, a third embodiment of the present invention will be described with reference to FIG. In the figure, the same parts as those of the previous embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the cross-sectional shape of the rubber layer 3 at the end is wedge-shaped so that the rubber layer 3 enters the sponge layer 2 inward. In that case, the through holes are formed as in the first embodiment. When a paper passing experiment was conducted on the roll for the fixing device of the present example, a decrease in the fixability at the end portion was observed because the elasticity at the end portion of the fixing roll gradually increased toward the end surface. No, of course
No sagging on the edges occurred. Further, since the end portion of the sponge layer 2 is configured to be closed by the rubber layer 3, it is possible to prevent foreign matter from entering the sponge layer and evaporation of the sponge constituent material.

[0018]

As described above, according to the present invention, since the rubber layer having higher elasticity than the sponge layer in the middle portion is provided at the end portion in the longitudinal direction of the fixing roller, the fixing roller is provided in the entire longitudinal direction. As a result, it is possible to make uniform contact and prevent deterioration of the sponge layer due to intrusion of foreign matter, oil, etc. for a long period of time and deterioration due to evaporation of the sponge constituent material.
Further, if the surface coating layer is formed only in the range of the sponge layer to expose the outer peripheral surface of the rubber layer portion, the frictional force with the driving side roller is ensured and the effect of preventing slippage is also obtained. obtain.

[Brief description of drawings]

FIG. 1 is a sectional view of a fixing roller as a first embodiment of the present invention.

FIG. 2 is a side view of the device of FIG.

FIG. 3 is a sectional view of a fixing roller as a second embodiment of the present invention.

FIG. 4 is a sectional view of a fixing roller as a third embodiment of the present invention.

FIG. 5 is a sectional view of a conventional fixing roller.

FIG. 6 is a side view of the FIG. 5 device.

FIG. 7 is an enlarged cross-sectional view showing an end portion of the device of FIG. 5 after long-term use.

[Explanation of symbols]

 1 core metal 2 sponge layer 3 rubber layer 4 through hole 5 surface coating layer

Claims (7)

[Claims] 1. A roll for a fixing device having a surface coating layer around a shaft-shaped core metal via a sponge layer, wherein a rubber layer is provided at an axial end of the sponge layer, and the rubber layer is provided around the core metal. And a roll for a fixing device, wherein a plurality of through holes extending through the sponge layer in the axial direction are formed. 2. The roll for a fixing device according to claim 1, wherein the through hole extends straight in the longitudinal direction of the cored bar. 3. The roll for a fixing device according to claim 1, wherein the through hole extends spirally in the longitudinal direction of the cored bar. 4. The roll for a fixing device according to claim 1, wherein the rubber layer is provided in a non-sheet passing area. 5. The roll for fixing device according to claim 1, wherein the surface coating layer is formed of a fluororesin. 6. The roll for a fixing device according to claim 1, wherein the surface coating layer is formed of a PFA tube. 7. The fixing device roll according to claim 1, wherein the sponge layer is formed of a mixture of fluororubber and fluororesin.