JP2810355B2 - Heat roller and heat roll fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat roller used in a heat roll fixing device, and more particularly to a heat roller having a short set-up time and a further reduced outer diameter deformation and bending. Further, the present invention relates to a heat roll fixing device having such a heat roller.

[0002]

2. Description of the Related Art A heat roll fixing device has been widely put into practical use as a fixing device of a copying machine or a printing apparatus. In this heat roll fixing device, a heat roller in which a release layer such as a fluorine resin layer or a silicon rubber layer is formed on an outer peripheral surface and a backup roller in which a thick silicon rubber or the like is formed on an outer peripheral surface are used. The recording paper on which the unfixed toner image is formed passes between these rollers, and the toner image is heated and fused by heat from the heat roller. The heat roller is formed in a hollow shape, and a heater such as a halogen lamp is disposed inside the heat roller. The heat roller is heated to about 170 ° C. to 180 ° C. by infrared light from an infrared lamp, and the toner image is heated and fused. ing.

In a heat roll fixing device, a pressing force is applied between a heat roller and a backup roller to elastically deform the backup roller to form an appropriate nip width, and a toner image is passed through the nip. Is heated and fused. Since the fixing performance is closely related to the nip width, it is extremely important to form a uniform nip width over substantially the entire length of the heat roller.

[0004]

In a copying machine having a heat roll fixing device, it is set so that the copying operation does not start unless the heat roller is heated to a preset temperature after the main switch of the main body is turned on. Therefore, it is important to shorten the rise time of the heat roller as much as possible. In order to shorten the start-up time during setup, it is conceivable to reduce the thickness of the roller body (for example, an aluminum core) of the heat roller as much as possible to reduce the heat capacity of the heat roller.

However, when the thickness of the core metal is reduced,
The rigidity of the roller is reduced, and as a result, not only the outer diameter of the roller is changed but also the roundness is reduced, and the paper passing property and the fixing property are significantly deteriorated.

Further, in the heat roller fixing device, since the heat roller and the pressure roller are pressed against each other, bending occurs in the heat roller. When bending occurs, the nip width at the central portion of the roller in the axial direction decreases, and the nip width at both ends in the axial direction increases. As a result, the inconvenience that the fixability of the central portion of the roller significantly deteriorates occurs. In particular, as the thickness of the core metal of the heat roller becomes thinner, the amount of bending is greatly increased, so that not only insufficient fixing appears, but also the paper passing performance is significantly deteriorated. On the other hand, if the thickness of the cored bar is increased to reduce the amount of bending, the heat capacity is increased, and there is a disadvantage that the start-up time during setup is lengthened. Thus, in the heat roll fixing device, the shortening of the startup time at the time of set-up and the prevention of the deformation and bending of the heat roller are contradictory, and measures for solving both of these items at once are still realized. It is not the fact.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a heat roller which can solve both the problems of shortening the set-up time and reducing the deformation and bending of the heat roller at once. It is a further object of the present invention to provide a heat roll fixing device having a greatly reduced set-up time and excellent paper passing performance and fixing performance.

[0008]

A heat roller according to the present invention comprises a hollow roller body having a release layer formed on an outer peripheral surface thereof, and a spiral coil spring disposed coaxially inside the roller body. Wherein the outer diameter surface of the spiral coil spring is disposed so as to press against the inner peripheral surface of the roller body.

The present inventor has conducted various experiments and analyzes on a method for increasing the rigidity of the heat roller, and has found that it is extremely effective to use a spiral coil spring as a reinforcing member. First, since the infrared lamp is disposed inside the heat roller, a reinforcing member located in a space around the axis of the heat roller cannot be disposed. However, since the coil spring can be coaxially arranged along the inner peripheral surface of the heat roller, a sufficient space for arranging the infrared lamp can be secured.

Next, the coil spring can have an extremely high outer shape holding ability by appropriately setting its material, quenching conditions, and the like, and has an outer shape that is hardly deformed even when a radially inward external force acts. Has holding ability.
In other words, as a characteristic of the coil spring, when the force in the axial direction is applied, the diameter of the coil spring is easily reduced or expanded, and the outer shape is easily deformed. There are characteristics that are difficult to do. Furthermore, utilizing the characteristic that the diameter of the coil spring is easily reduced by applying a tensile force in the axial direction, the coil spring is inserted into the heat roller in a reduced diameter state, and then is opened. A radial outward pressing force is generated against the peripheral surface. This pressing force is a strong resistance to a radially inward force acting from the pressing roller. Furthermore, since the portion of the coil spring that is not opposed to the pressure roller is restrained by the heat roller, an elastic repulsion is generated in the coil spring itself with respect to the pressing force from the pressure roller. Acts to prevent deformation of the roller.
Therefore, by appropriately utilizing the outer shape holding performance of the coil spring itself, the radial outward pressing force, and the repulsive force against the pressing force, the outer shape of the heat roller, that is, the circularity, with respect to the pressing force from the pressing roller. Properly maintained.
By maintaining the concentricity of the heat roller, the bending amount can be suppressed to an extremely small range.

[0011] By reducing the amount of bending,
Even when a large pressing force is applied between the heat roller and the pressure roller, a uniform pressing force can be applied over the entire length of the heat roller, and a uniform nip width can be formed. As a result, it is possible to realize a heat roll fixing device in which the fixing property and the paper passing property are further improved.

Further, by utilizing the reinforcing force of the spiral coil spring, the thickness of the heat roller can be further reduced, and as a result, the start-up time during setup can be greatly reduced.

Further, the heat roller according to the present invention is formed with a roller portion having a release layer formed on the outer peripheral surface, and formed on both sides of the roller portion by drawing so as to have a diameter smaller than the outer diameter of the roller portion. A hollow roller body having a journal portion for connecting a drive mechanism, and a shoulder connecting the roller portion and the journal portion; and a roller body disposed inside the roller body so as to be in pressure contact with the inner peripheral surface thereof. A coil spring having a spiral shape, wherein the coil spring is held by shoulders formed at both ends. Thus, by forming the journals and shoulders at both ends of the roller body by drawing, the shoulders extend in a plane perpendicular to the roller axis, and the shoulders themselves also have a reinforcing effect on bending. In addition, the occurrence of bending can be further prevented. In addition, the shoulder can prevent the axial movement of the coil spring. Particularly, when the roller body is manufactured from a thin metal tube, the shoulder and the journal can be easily formed by drawing. Therefore, forming the shoulder by drawing is difficult in manufacturing and at both ends. It is extremely effective as a reinforcing member for bending.

Further, according to the method of manufacturing a heat roller of the present invention, there is provided a heat roller having a roller portion having a release layer formed on an outer peripheral surface, and a spiral coil spring for reinforcement being loaded inside. In doing this, a cylindrical metal tube is prepared, the diameter of the spiral coil spring is reduced by applying a tensile force, the contracted coil spring is inserted inside the metal tube, and then the tensile force is released. The coil spring is pressed against the inner peripheral surface of the metal tube, and both ends of the metal tube on which the coil spring is arranged are drawn,
A journal portion having a diameter smaller than the outer diameter of the roller portion, and a shoulder portion connecting the journal portion and the roller portion are formed, and a coil spring disposed inside is held by shoulder portions formed at both ends of the metal tube. It is characterized by. In this manner, by arranging the coil spring inside the metal tube and thereafter performing drawing on both ends, a shoulder having a reinforcing effect on bending and a holding performance of the coil spring can be formed by a simple processing. In particular, when a thin metal tube is used to reduce the heat capacity, the shoulder and the journal can be easily formed by drawing, so forming the shoulders at both ends of the roller body by drawing is not possible. This is extremely beneficial in conjunction with reducing heat capacity and reducing set-up time.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagrammatic sectional view showing the structure of an example of a heat roll fixing device according to the present invention.
FIG. 1 is a diagrammatic sectional view showing a configuration of an example of a heat roller according to the present invention. Heat roller fixing device is heat roller 1
And a pressure roller 2, which support the axes so as to be parallel to each other. The heat roller 1 is rotatably supported on frames 4a and 4b via bearings 3a and 3b. The heat roller 1 has a hollow shape, and an infrared lamp 5 serving as a heating source is disposed therein. Attach a gear 6 to one end of the heat roller 1,
It is connected to the drive mechanism on the main body side via this gear.

The pressure roller 2 is formed with a heat-resistant elastically deformable elastic rubber layer such as silicon rubber, for example, and its both ends are rotatable on separate frames 8a and 8b via bearings 7a and 7b, respectively. To support. The bearings 7a and 7b are each provided with a spring 9 serving as a pressing means.
The pressure roller 2 is connected to the heat roller 1 by the springs 9a and 9b. The pressing force of the springs 9a and 0b can be set freely according to the required specifications.
g. As the pressing means, various types of elastic members other than springs can be used in the illustrated form.
The pressing force is set such that an appropriate nip width is formed in consideration of the hardness and elastic force of the elastic rubber layer of the pressure roller 2, the paper feeding speed, the set temperature, and the like.

As shown in FIG. 2, the heat roller 1 has a roller body 10 of an aluminum pipe having a cylindrical thickness of about 0.3 to 0.8 mm, for example. 11 is formed. The release layer 11 can be composed of a fluororesin having high releasability, oil-impregnated silicone rubber, or a silicone rubber layer having a fluororesin layer formed on the surface thereof. At both ends of the roller body 10, journal portions 12a and 12b for connecting a driving mechanism are provided. The roller body 10 has a straight shape having a constant outer diameter along its axis, or a crown shape in which the outer diameter gradually increases and decreases along the axis or an inverted crown shape in which the outer diameter gradually decreases and increases. be able to.

In this embodiment, the outer diameter of the roller body is 30φ and the inner diameter is 29φ. A spiral coil spring 1 is provided inside the roller body 10 so as to be pressed against the inner peripheral surface thereof.
3 are arranged coaxially. The coil spring 13 is made of a slantless wire having a wire diameter of 1.5 mm, and has an outer diameter of, for example,
0φ, and the coil pitch is 18 mm.

The wire diameter, outer diameter, and coil pitch of the spiral coil spring 13 are determined in consideration of the setup start-up time, the thickness of the core metal of the roller body, the pressure applied between the heat roller and the pressure roller, and the like. And set according to the use and performance of the fixing device.

Next, a method of manufacturing the heat roller shown in FIG. 2 will be described. An aluminum tube having a predetermined outer diameter and inner diameter is prepared. The length of the aluminum tube in the axial direction is the sum of the paper passing width and the portion constituting the journal portion, and the length of the coil spring is a length corresponding to the paper passing width. Next, the coil spring is inserted into a predetermined axial position with its diameter reduced inside the raw tube by applying a tensile force in the axial direction to the coil spring, and then opened. By releasing the tensile force, the diameter of the coil spring is increased and the coil spring is pressed and held on the inner peripheral surface of the raw tube. Next, both ends constituting the journal portion are formed by drawing. Thereafter, a release layer is formed on the outer peripheral surface of the raw tube. According to this configuration, the coil spring can be easily disposed inside the roller body even if the heat roller has a journal portion having a diameter smaller than the outer diameter of the roller body.

FIG. 4 shows a modification of the heat roller according to the present invention. In this example, a straight roller body without a journal portion is used as the roller body 10. In this case, the bearing and the driving element are directly connected to both ends. In this case, drawing work becomes unnecessary, and the manufacturing operation becomes easy.

Next, a description will be given of a performance comparison between a heat roller incorporating a spiral coil spring and a heat roller not incorporating a spiral coil spring. A-3 size heat roller for a commercial copying machine was prepared and its performance was compared. The heat roller used in the experiment had an outer diameter of 30φ and an inner diameter of 2
8.8φ. The crimping force is 7 kg on one side and a total of 1
4 kg. The coil spring used has a wire diameter of 1.5 mm,
The outer diameter was 30φ and the coil pitch was 18 mm. In the experiment, A-5052 and A606 were used as heat roller materials.
3 using two types of aluminum materials and having a wall thickness of 0.3.
Three types of rollers of 4t, 0.5t and 0.6t were prototyped.

The measurement items are a setup start-up time required to raise the temperature from room temperature to a set temperature of 185 ° C., and a change in the outer diameter of the heat roller. This change in outer diameter is
As shown in FIG. 3, since the cross section of the heat roller is deformed into an elliptical shape during pressure bonding, the outer diameter Δd of the elliptical shape is measured.
It is represented by an increment Δd-30 from 0φ. The measurement position of the change in the outer diameter is the center position in the axial direction of the heat roller. Further, using a 600 W halogen lamp, 18
The time required to raise the temperature to 5 ° C. was measured. The experimental results are shown in Tables 1 and 2.

[0024]

[Table 1]

[0025]

[Table 2]

As is clear from Tables 1 and 2, the change in the outer diameter of the heat roller provided with the coil spring is reduced to almost half that of the heat roller without the coil spring.
From this measurement result, it is clear that the concentricity of the heat roller is greatly improved by the reinforcing effect of the coil spring, and therefore the bending is also greatly improved. Further, the rise time is reduced by about 10% by providing the coil spring. However, the rise time is reduced by about 30% as compared with a roller having the same change in the outer diameter.

The present invention is not limited to the embodiment described above, and various modifications and changes are possible. For example, in the above-described embodiment, a coil spring is provided over substantially the entire length of the roller body.
A desired effect can be obtained even when the coil spring is arranged over a part of the sheet passing width, not necessarily over the entire length. In this case, when coil springs are present near both ends supporting the roller body, a remarkable effect on bending can be exerted.

[0028]

As described above, according to the present invention, since a spiral coil spring is crimped inside the roller body, the rigidity of the roller is further increased, and as a result, a thin roller body is used. However, it is possible to realize a heat roller with further improved bending amount, outer diameter dimension and roundness. Further, since the thickness of the roller body can be further reduced, the start-up time during setup can be greatly reduced without increasing the amount of bending or deteriorating roundness.

Further, in the heat roll fixing device according to the present invention, since a heat roller having higher rigidity as a roller is used, the fixing performance and the paper passing performance are greatly improved.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a configuration of an example of a heat roll fixing device according to the present invention.

FIG. 2 is a schematic sectional view showing the configuration of an example of a heat roller according to the present invention.

FIG. 3 is a diagram showing a change in outer shape of a heat roller.

FIG. 4 is a schematic sectional view showing a modification of the heat roller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat roller 2 Pressure roller 3a, 3b, 7a, 7b Bearing 4a, 4b, 8a, 8b Frame 5 Infrared lamp 6 Gear 10 Roller body 11 Release layer 12a, 12b Journal part 13 Spiral coil spring

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H05B 3/00 335 G03G 15/20 102 G03G 15/20 103

Claims (4)

(57) [Claims] 1. An outer diameter surface of a spiral coil spring, comprising: a hollow roller body having a release layer formed on an outer peripheral surface; and a spiral coil spring disposed coaxially inside the roller body. The heat roller is disposed so as to press against the inner peripheral surface of the roller body. 2. A hollow heat roller having a release layer formed on an outer peripheral surface thereof, and a heat roller disposed substantially parallel to the heat roller and having an elastic layer capable of being elastically deformed formed on an outer peripheral surface thereof. A heat roller comprising: a pressure roller; pressing means for pressing the heat roller and the pressure roller against each other; a heating source disposed inside the heat roller; and a drive mechanism for driving the heat roller and the pressure roller. In the roll fixing device, the heat roller is disposed coaxially with a hollow roller body having a release layer formed on an outer peripheral surface thereof, and an outer diameter surface is provided on an inner peripheral surface of the roller body. A heat roll fixing device comprising a spiral coil spring arranged so as to be in pressure contact with the heat roll fixing device. 3. A roller portion having a release layer formed on an outer peripheral surface thereof. The roller portion is formed on both sides of the roller portion by drawing so as to have a diameter smaller than the outer diameter of the roller portion. A hollow roller body having a journal portion, a shoulder connecting the roller portion and the journal portion, and a spiral coil spring disposed inside the roller body so as to be pressed against an inner peripheral surface thereof. A heat roller, wherein the coil spring is held by shoulders formed at both ends. 4. When manufacturing a heat roller having a roller portion having a release layer formed on its outer peripheral surface and having a spiral coil spring for reinforcement mounted inside, a cylindrical metal tube is used. Prepare, apply a tensile force to the spiral coil spring to reduce the diameter, insert the contracted coil spring inside the metal tube, then release the tensile force and place the coil spring on the inner peripheral surface of the metal tube. Pressed, the both ends of the metal tube in which the coil spring is disposed inside are subjected to drawing processing to form a journal portion smaller in diameter than the outer diameter of the roller portion, and a shoulder portion connecting the journal portion and the roller portion. A method for manufacturing a heat roller, wherein coil springs arranged inside are held by shoulders formed at both ends of the metal tube.