JP3196710B2 - Heating roller, metal material used for manufacturing the roller, and image forming apparatus using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating roller, a metal material used for manufacturing the heating roller, and an image forming apparatus using the same, and more particularly, to an effective method for increasing the heat conductivity and strength of the heating roller. The present invention relates to a heating roller, a metal material used for manufacturing the heating roller, and an image forming apparatus using the same.

[0002]

2. Description of the Related Art In a heating roller used in a fixing section of an image forming apparatus such as a printer or a copying machine, in order to improve heat conductivity to a material to be heated, a core metal constituting the heating roller is used. In general, metals having high thermal conductivity such as aluminum alloys are used.

The above-described heating roller acts to apply heat while rotating while applying a predetermined pressure to the material to be heated at the time of fixing an image. Therefore, the heating roller only withstands the force from the pressing and rotating mechanism. Strength is required. Therefore, when an aluminum alloy is used as the core metal of the heating roller as described above, the thickness thereof must be large enough to withstand the above-described force. Since the use of such a thick aluminum alloy is costly, it is known that the cost is reduced by using an iron-based metal core.

As described above, when an iron-based material is used, the iron-based material has poor heat conductivity as compared with an aluminum alloy. , It is necessary to make the thickness thinner.

However, since iron-based materials are difficult to process,
When the outer diameter of the iron-based material is changed by turning or grinding, if the wall thickness is to be reduced, a scale-like unevenness or an elliptical shape is generated on the processed surface. Therefore, it has been difficult to improve the heat conductivity only with an iron-based material and finish the surface of the heating roller to a desired smoothness.

In order to solve this problem, Japanese Patent Application Laid-Open No. 221149/1990 discloses that a tubular base made of aluminum is provided on the outer peripheral surface of a tubular base made of iron, and the aluminum base is subjected to surface processing. The technique configured as described above is disclosed.

The composite pipe made of iron and aluminum is manufactured as follows. First, a composite pipe material is obtained in which a tubular base material made of iron is inserted into a pipe made of aluminum having an inner diameter matching the outer diameter of the base material. Thereafter, the composite pipe material is subjected to drawing with a die having an outer diameter smaller than the outer diameter of the aluminum pipe, and the iron and aluminum pipes are brought into close contact with each other.

[0008]

However, Japanese Patent Application Laid-Open No. Hei 2-2
When the composite pipe material is formed by the drawing method described in Japanese Patent No. 11469, uneven thickness occurs on the aluminum side having a low material hardness due to a difference in a lubricant used in drawing and a difference in the material hardness. There has been a problem that the temperature distribution varies, and a constant amount of heat cannot be supplied to the material to be heated.

In order to solve the above problem, it is necessary to precisely polish the surface of the aluminum, and this polishing is costly. Therefore, this composite pipe is not suitable as a core metal for a heating roller. Was.

A release layer made of a resin such as a fluorine resin is formed on the outer periphery of the heating roller. However, the coating of the release layer needs to be subjected to a rust-preventive treatment. As the rust material, a heat-resistant zinc phosphate film-based material has been used.

However, since the treated surface of the zinc phosphate film-based rust preventive is rough, when the resin bearing is used for rotating the heating roller, there is a problem that the treated surface wears the resin bearing. Was.

Accordingly, the present invention provides a heating roller which prevents deformation of a composite tube material generated at the time of a cold working method, has high thermal conductivity and strength, and prevents abrasion of a resin bearing serving as a roller bearing. It is an object of the present invention to provide a metal material used for the production and an image forming apparatus using the same.

[0013]

According to one aspect of the present invention, there is provided a heating roller for use in a fixing device of an image forming apparatus, the first roller having a predetermined coefficient of thermal expansion. A first base formed of a tube, and a second base formed of a second metal pipe provided in close contact with the outer peripheral surface of the first base and having a smaller coefficient of thermal expansion than the first metal pipe. Wherein the second base is provided with a heat supply unit in which the thickness of the second metal tube is reduced at a position where the material to be heated is conveyed.

According to a second aspect of the present invention, in the first aspect of the present invention, the second metal tube has a material hardness higher than that of the first metal tube.

[0015] The invention of claim 3 is the invention of claim 1 or 2, further comprising a resin layer covering the peripheral surface of the heat supply section.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the second base is bent at a predetermined gap in the direction of the first base outside an end face of the first base. A bent portion, wherein the bent portion has the first base and the second base.
A bearing mounting portion for mounting a bearing for rotating the base is formed.

According to a fifth aspect of the present invention, in the fourth aspect of the invention, the bearing mounting portion includes a coating portion having a rust-proof coating on a contact surface with the bearing, and the coating portion includes the coating portion. It has a coating surface in which a metal is impregnated in a pinhole formed on the surface of the substrate.

According to a sixth aspect of the present invention, in the first aspect, the metal tube forming the first base is an aluminum-based metal tube, and the metal tube forming the second base is , Characterized in that it is an iron-based metal tube.

According to a seventh aspect of the present invention, there is provided a transfer means for transferring a toner image to a transfer material, and a fixing means for heating and pressing the transfer material on which the toner image has been transferred by the transfer means to fix the toner image. In the image forming apparatus provided with the fixing device, the fixing unit is provided in close contact with a first base formed of a first metal tube having a predetermined coefficient of thermal expansion, and an outer peripheral surface of the first base. A second base formed of a second metal pipe having a smaller coefficient of thermal expansion than the first metal pipe, wherein the second base is located at a position where a material to be heated is conveyed. A heating roller having a heat supply unit in which the thickness of the metal tube is reduced is provided.

[0020] The invention according to claim 8 is a metal tube material used for manufacturing a heating roller used in a fixing device of an image forming apparatus, wherein the first metal tube has a predetermined coefficient of thermal expansion; A second metal pipe, which is provided in close contact with the outer peripheral surface of the first metal pipe and has a smaller coefficient of thermal expansion than the first metal pipe, wherein an end face of the second metal pipe is 1
The second metal pipe is located outside the end face of the metal pipe, and the second metal pipe has a heat supply unit in which the thickness at the position where the material to be heated is conveyed is reduced.

According to a ninth aspect of the present invention, in the eighth aspect of the present invention, the second metal tube has a material hardness higher than that of the first metal tube.

According to a tenth aspect of the present invention, in the eighth aspect of the present invention, the first metal tube is an aluminum-based metal tube, and the second metal tube is an iron-based metal tube. It is characterized by the following.

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a heating roller according to the present invention, a metal material used for manufacturing the same, and an image forming apparatus using the same will be described in detail with reference to the accompanying drawings.

First, the outline of the present invention will be described with reference to FIG. FIG. 1 is a sectional view showing the structure of the heating roller according to the present invention.

According to the present invention, as shown in the figure, an iron tube 1 having a small coefficient of thermal expansion is brought into close contact with the outer peripheral surface of an aluminum tube 2 having a large coefficient of thermal expansion, and a material to be heated is conveyed on the surface of the iron tube 1. Grind and thin according to the position. In addition, by providing a rust-preventive coating 5 having a smooth treated surface on the bearing mounting portion 12 serving as a shaft of the roller, deformation of the composite pipe material generated at the time of the cold construction method is prevented, and thermal conductivity and strength are increased. Another object of the present invention is to provide a heating roller for preventing abrasion of a resin bearing serving as a roller bearing, a metal material used for manufacturing the heating roller, and an image forming apparatus using the same.

The iron tube 1 may be a metal tube made of an iron-based alloy containing iron as a main component, and the aluminum tube 2 may be a metal tube made of an aluminum-based alloy containing aluminum as a main component. There may be. Hereinafter, the terms “iron tube” and “aluminum tube” mean the above metals.

Hereinafter, the structure of the heating roller according to the present invention will be described in more detail with reference to FIG. The heating roller according to the present invention is used for a fixing unit in an image forming apparatus such as a printer. The fixing unit includes a heating roller that heats the transfer material on which the toner image is formed, and a pressure roller that presses the transfer material, and heat-presses the transfer material to fix the toner image on the transfer material. Let it.

As shown in FIG. 1, the heating roller according to the present invention has therein a heat source 4 serving as a heat source for heating the transfer material, and transfers the heat generated from the heat source 4 to the aluminum tube 2. Then, heat is supplied to the transfer material via the iron tube 1. As the heat source 4, a heater of about 800 W is used.

Since the aluminum tube 2 and the iron tube 1 serve as a medium for supplying heat to a material to be heated such as a transfer material, to shorten the warm-up time and reduce power consumption,
In general, it is preferable to transfer heat as quickly as possible,
Since the aluminum alloy has a high thermal conductivity, the thickness of the aluminum tube 2 does not particularly matter when it comes to the requirement of the thermal conductivity. It becomes a problem.

Therefore, in the heating roller according to the present invention,
As shown in FIG. 1, an iron pipe 1
Is provided with a heat supply unit 10 having a reduced thickness. As described above, by reducing the thickness of the metal tube having a small thermal conductivity corresponding to the position where the material to be heated is conveyed, it is possible to improve the speed of supplying heat to the material to be heated.

In the heat supply unit 10 as described above, the strength of the thinned portion is weakened. However, in the present invention, the heat supply unit 10 is provided on the outer peripheral surface of the metal tube having a high coefficient of thermal expansion. As a result, the metal tube expands during heating to exert a force to push up the heat supply unit 10, so that the strength of the heat supply unit 10 can be increased and a uniform load can be applied to the material to be heated.

As shown in this embodiment, when aluminum is used as the metal tube having a large coefficient of thermal expansion and iron is used as the metal tube provided on the outer peripheral surface, the difference in the coefficient of thermal expansion between aluminum and iron causes 0.06 tube diameter
It expands toward the iron tube side by about mm to 0.1 mm and applies force.

The upper surface of the heat supply unit 10 shown in FIG. 1 is coated with a resin such as a fluororesin in order to increase the degree of adhesion to the material to be heated. Abutted.

As described above, the heat supply unit 1 in which the iron tube 1 is thinned
By coating the surface of No. 0 with the resin layer 3, the degree of adhesion of the material to be heated is increased, so that the effect of supplying heat can be efficiently performed.

Further, the heating roller according to the present invention is provided with a bent portion 11 formed by bending the iron tube 1 toward the aluminum tube 2 outside the end surface of the aluminum tube 2 as shown in FIG. Have been. The bent portion 11 is formed about 3 mm outside the end face of the aluminum tube 2. The bent portion 11 and the end face of the aluminum tube 2 may be brought into contact with each other from the beginning, but it is preferable to provide a certain gap in consideration of the thermal expansion of the aluminum tube 2. That is, the distance between the end surface of the aluminum tube 2 and the bent portion 11 is determined by the coefficient of thermal expansion of the aluminum tube 2 and the aluminum tube 2.
Is determined in consideration of the temperature rise by the heat source 4.

It is preferable that the length of bending the iron tube 1 be greater than the thickness of the aluminum tube 2.
As shown in FIG. 1, an iron tube 1 is formed so as to cover an aluminum tube 2.

As described above, by providing the bent portion 11 outside the end face of the metal tube having a large coefficient of thermal expansion, even if the metal tube is thermally expanded, a change in the length can be suppressed. .

Since the heating roller as described above conveys the material to be heated while rotating, bearing attachment portions 12 for attaching bearings are provided at both ends of the heating roller. As shown in FIG. 1, the bearing mounting portion 12 has a throttle structure in which both ends of the iron tube 1 are narrowed to a small diameter.

As described above, by forming the bearing mounting portion 12 with a metal having a small coefficient of thermal expansion and a high strength, the strength against the rotation of the heating roller can be increased, and when the temperature of the metal rises. Even if there is, it is possible to prevent the bearing mounting portion 12 from being affected by the temperature.

A resin bearing is mounted on the bearing mounting portion 12. Since the resin bearing is easily affected by the treated surface of the bearing mounting portion 12, in the present invention,
The surface of the bearing mounting portion 12 is coated with a zinc phosphate film, and a pinhole formed on the surface of the zinc phosphate film is impregnated with a metal such as zinc, copper, or tin.

As described above, by coating the bearing mounting portion with the coating material impregnated with metal on the surface pinhole portion of the zinc phosphate film, rust prevention due to heat and smoothness of the treated surface can be improved, and the bearing can be improved. Even if a resin bearing is used as the material, wear of the bearing can be prevented.

The heating roller according to the present invention comprises a transfer means for forming a toner image on a transfer material, and a fixing means for heating and pressing the transfer material onto which the toner image has been transferred by the transfer means to fix the toner image. It is used for the fixing means of an image forming apparatus provided.

As described above, since the heating roller according to the present invention is used for the fixing means of the image forming apparatus, heat is uniformly supplied to the entire surface of the transfer material, so that image unevenness which is likely to occur during fixing can be prevented. can do.

Next, a method of manufacturing the heating roller shown in FIG. 1 will be described with reference to FIGS.

FIG. 2 is a cross-sectional view showing a step of inserting the aluminum tube 2 inside the iron tube 1 in the method of manufacturing the heating roller shown in FIG. In the figure, the inner diameter is 34 mm,
An inner diameter of 28 mm, a thickness of 0.7 mm is applied to an iron tube 1 having a thickness of 0.7 mm.
The example which inserts the aluminum tube 2 of mm is shown. Although the same length is used as the iron tube 1 and the aluminum tube 2 in the same figure, if a short length is used as the aluminum tube 2, the grinding process shown in FIG. You can also.

Next, the composite pipe obtained by the above insertion step is inserted into a die having an inner diameter of 31 mm, and the iron pipe 1 and the aluminum pipe 2 are brought into close contact by a cold drawing method or an extrusion method.

FIG. 3 is a cross-sectional view showing a state in which the iron pipe 1 and the aluminum pipe 2 are in close contact with each other by the cold drawing method or the extrusion method. In the composite pipe shown in the figure, since the iron pipe 1 having a high material hardness is narrowed by a die, the thickness of the aluminum pipe 2 having a soft material hardness is hardly affected, and the aluminum pipe 2 changes only by about 0.02 mm. No result was obtained.

Since the aluminum tube 2 is a main medium for heat conduction, it is very important that the thickness does not change in the manufacturing process of the heating roller.

As described above, according to the present invention, since a metal tube having a large material hardness is formed on the outside, deformation at the time of cold drawing or extrusion is prevented, so that a close and accurate composite tube can be manufactured. it can.

Next, as shown in FIG. 4, both ends of the aluminum pipe 2 of the composite pipe obtained as described above are ground.

FIG. 4 is a sectional view showing a state where the composite pipe shown in FIG. 3 is ground. The grinding length of the aluminum tube is determined in consideration of the positions of the bearing mounting portion 12 and the bent portion 11 shown in FIG.

Next, as shown in FIG. 5, drawing is performed on the ground portion to reduce the diameter of both ends of the iron tube 1.

FIG. 5 is a sectional view showing a state in which a bearing mounting portion is formed on the composite pipe shown in FIG. As shown in the figure,
The position where the iron tube 1 is bent is a position slightly apart from both ends of the aluminum tube 2.

Next, as shown in FIG. 6 (FIG.
FIG. 2 is a cross-sectional view showing a state where the surface of FIG. 1 is ground to form the heat supply unit 10 shown in FIG. 1. ), The surface of the iron tube 1 is ground corresponding to the position where the material to be heated is conveyed to a thickness of about 0.3 mm.

At this time, in the present invention, the presence of the aluminum tube 2 on the inner peripheral surface of the iron tube 1 acts to reinforce the iron tube 1 during grinding. Prevents the occurrence of irregularities that occur during
The heat supply unit 10 having a small thickness and high surface accuracy can be formed.

Next, as shown in FIG. 7 (FIG. 7 is a sectional view showing a state in which a resin layer is formed on the upper surface of the iron tube 1 shown in FIG. 6), the upper surface of the heat supply unit 10 is made of fluororesin. And the surface of the bearing mounting portion is coated with a zinc phosphate film. Here, as shown in the figure, the coating of the heat supply unit 10 is preferably performed from the thick part so that the thin part is completely covered with the resin.

The rust-preventive coating 5 applied to the surface of the bearing mounting portion 12 is formed by immersing the bearing mounting portion 12 in a zinc phosphate solution to form a zinc phosphate film, and performing pinholes of the zinc phosphate film by replacement sealing treatment. Part is impregnated with metal such as zinc, copper and tin.

Here, this rust-proof coating may be applied to the entire surface of the iron pipe before the aluminum pipe 2 shown in FIG. 2 is inserted, or after the adhesion step shown in FIG. 3, the grinding step shown in FIG. The present invention can be applied to any stage after the drawing process shown in FIG. 5 and after the grinding process shown in FIG. 6 and the coating of the entire surface of the composite pipe or only the surface of the bearing mounting portion. The effect of can be obtained.

Finally, if the heat source 4 is inserted and fixed,
Can be obtained.

In addition to the above-described steps, the inner surface of the composite pipe may be subjected to a black treatment in order to efficiently absorb the heat generated from the heat source 4.

[0078]

As described above, according to the present invention,
A heating roller that prevents deformation of the composite pipe material generated during the cold construction method, has high thermal conductivity and strength, and prevents abrasion of a resin bearing serving as a roller bearing, and a metal material used for the production thereof, and And an image forming apparatus using the same.

Further, by reducing the thickness of the metal tube having a small thermal conductivity corresponding to the position where the material to be heated is conveyed, the speed of supplying heat to the material to be heated can be improved.

In the present invention, since the heat supply unit 10 is provided on the outer peripheral surface of the metal tube having a high coefficient of thermal expansion, the metal tube expands at the time of heating and a force to push up the heat supply unit 10 acts. The strength of the supply unit 10 can be increased, and a uniform load can be applied to the material to be heated.

Further, by coating the surface of the heat supply section 10 having the thinned iron tube 1 with the resin layer 3, the degree of adhesion of the material to be heated is increased, so that the heat supply effect can be efficiently performed.

Further, by providing the bent portion 11 outside the end face of the metal tube having a large coefficient of thermal expansion, even if the metal tube is thermally expanded, a change in the length can be suppressed.

Further, by forming the bearing mounting portion 12 with a metal having a small coefficient of thermal expansion and a high strength, the strength against rotation of the heating roller can be increased and the temperature of the metal increases. Also, the bearing mounting part 12
Can be prevented from being affected by temperature.

Further, by coating the bearing mounting portion with a coating material impregnated with metal on the surface pinhole portion of the zinc phosphate film, rust prevention due to heat and smoothness of the treated surface can be improved. Even when a bearing is used, wear of the bearing can be prevented.

Further, by using the heating roller according to the present invention for the fixing means of the image forming apparatus, the heat is uniformly supplied to the entire surface of the transfer material. Can be.

In addition, by forming a metal tube having a large material hardness on the outside, deformation at the time of cold drawing or extrusion is prevented, so that it is possible to manufacture a close and accurate composite tube.

Further, in the present invention, the presence of the aluminum tube 2 on the inner peripheral surface of the iron tube 1 allows the iron tube 1 to be ground during grinding.
To prevent the occurrence of irregularities that occur when the iron tube 1 is made thinner, which is a conventional problem, and to form the heat supply unit 10 having a small thickness and high surface accuracy. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of a heating roller according to the present invention.

FIG. 2 shows a method of manufacturing the heating roller shown in FIG.
Sectional drawing which shows the process of inserting the aluminum pipe 2 inside the iron pipe 1. FIG.

FIG. 3 is a sectional view showing a state in which the iron pipe 1 and the aluminum pipe 2 are in close contact with each other by a cold drawing method or an extrusion method.

FIG. 4 is a sectional view showing a state where the composite pipe shown in FIG. 3 is ground;

FIG. 5 is a sectional view showing a state in which a bearing mounting portion is formed on the composite pipe shown in FIG. 4;

FIG. 6 is a diagram showing a heat supply unit 1 shown in FIG.
Sectional drawing which shows the state which formed 0. FIG.

FIG. 7 is a sectional view showing a state in which a resin layer is formed on the upper surface of the iron tube 1 shown in FIG. 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Iron pipe, 2 ... Aluminum pipe, 3 ... Resin layer, 4 ... Heat source, 5 ... Rust prevention coating, 10 ... Heat supply part, 11 ... Bent part, 12 ... Bearing mounting part.

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Claims (10)

(57) [Claims] 1. A heating roller used in a fixing device of an image forming apparatus, wherein a first roller formed of a first metal tube having a predetermined coefficient of thermal expansion.
A first substrate, which is provided in close contact with an outer peripheral surface of the first substrate,
And a second base formed of a second metal tube having a smaller coefficient of thermal expansion than the metal tube of the above, wherein the second base is located at a position where a material to be heated is conveyed. A heating roller comprising a heat supply unit having a reduced thickness. 2. The heating roller according to claim 1, wherein the second metal pipe has a material hardness higher than that of the first metal pipe. 3. The apparatus according to claim 1, further comprising a resin layer covering a peripheral surface of the heat supply unit.
A heating roller as described in the above. 4. The second substrate has a bent portion that is bent outside of an end face of the first substrate at a predetermined gap in the direction of the first substrate, and the bent portion has the bent portion. 2. The heating roller according to claim 1, wherein a bearing mounting portion for mounting a bearing for rotating the first base and the second base is formed. 5. The bearing mounting portion includes a coating portion in which a contact surface with the bearing is rust-proof coated, wherein the coating portion is formed by impregnating a pinhole portion formed on the surface of the coating portion with metal. The heating roller according to claim 4, wherein the heating roller has a coated surface. 6. The metal tube forming the first base is an aluminum-based metal tube, and the metal tube forming the second base is an iron-based metal tube. Item 2. A heating roller according to Item 1. 7. An image forming apparatus comprising: a transfer unit for transferring a toner image onto a transfer material; and a fixing unit for fixing the toner image by heating and pressing the transfer material onto which the toner image has been transferred by the transfer unit. The fixing unit includes a first metal tube formed of a first metal tube having a predetermined coefficient of thermal expansion.
A first substrate, which is provided in close contact with an outer peripheral surface of the first substrate,
And a second base formed of a second metal tube having a smaller coefficient of thermal expansion than the metal tube of the above, wherein the second base is located at a position where a material to be heated is conveyed. An image forming apparatus comprising: a heating roller having a heat supply unit having a reduced thickness. 8. A metal tube material used for manufacturing a heating roller used in a fixing device of an image forming apparatus, comprising: a first metal tube having a predetermined coefficient of thermal expansion; and an outer periphery of the first metal tube. A second metal pipe provided in close contact with a surface and having a smaller coefficient of thermal expansion than the first metal pipe, wherein the end face of the second metal pipe is more than the end face of the first metal pipe. The metal tube material, wherein the second metal tube has a heat supply unit in which the thickness of the position where the material to be heated is conveyed is reduced. 9. The metal tube material according to claim 8, wherein the second metal tube has a material hardness higher than that of the first metal tube. 10. The metal tube material according to claim 8, wherein the first metal tube is an aluminum-based metal tube, and the second metal tube is an iron-based metal tube.