JPH03239278A - Fixing device for electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To facilitate maintenance and to prolong the life of a device by attachably/detachably providing a heat insulating material which absorbs mechanical impact and fatigue by heating occurring on a follower shaft when the fixing device works on the outside of the follower shaft. CONSTITUTION:An NB collar 17 is press-fitted in a composite type bearing 16 which is press-fitted in a flange 15 and heat insulating plastic collar 20 whose thickness is several mm and which can be detached is mounted on the outside of the collar 17. By attachably/detachably mounting the heat insulating material 20 made of plastic on the outside of the follower shaft 12, the life of the shaft 12 is prolonged and the plastic collar 20 is easily replaced. Therefore, the life of the follower shaft 12 is drastically prolonged by replacing it before attaining a fatigue limit value. Thus, maintenance is easily performed and the life of the follower shaft 12, consequently, the life of the fixing device is greatly prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a fixing device for an electrophotographic machine, and particularly to the structure of a fixing roll.

[Conventional technology]

FIG. 4 shows a system diagram of a conventionally used electrophotographic system. In the figure, ]- is a charger, 2 is a photoreceptor charged by the charger 1, 3 is a laser beam that forms an electrostatic latent image on the photoreceptor 2, and 4 is a developer that visualizes the electrostatic latent image. , 5
7 is a transfer device that transfers the toner image formed by the developing device 4 onto paper 6; 7 is a fixing roll that heats and presses the paper 6 to which the toner image has been transferred; 8 is a heat roll for heating; and 9 is a heating roll. This is a backup roll for pressure.

A photoreceptor 2 whose surface is uniformly charged by a charger 1 is irradiated with a laser beam 3 to form an electrostatic latent image, and a developer 4 supplies toner to the photoreceptor 2 for development. This toner is then transferred onto paper 6 by transfer device 5. The paper 6 that has been transferred is sent to a fixing roll 7, passes between a heat roll 8 and a backup roll 9, and is heated and pressurized to complete the fixing.

FIG. 5, FIG. 6, and FIG. 7 show a sectional view of the fixing roll, an exploded view of the heat roll, and a sectional view of the driven shaft, respectively. In each figure, 10 is a heater lamp, 1
1 is an opening shaft of the heat roll 8, 12 is a driven shaft of the heat roll 8, 13 is a drive key 14 that connects the opening shafts 1, 1- of the heat roll 8, and a fixing frame 15 is a driven shaft that supports the fixing roll 7. 2 is a flange, 16 is a composite type bearing, 17 is a collar, J8 is a heat insulating material installed between the composite type bearing 16 and collars 1-7, and 19 is a buffer spring.

The heat roll 8 is made of a metal having good thermal conductivity and whose surface is coated with a non-adhesive resin such as Teflon or silicone rubber, and has a heater lamp and an O removably attached therein. The backup roll 9 has a metal core coated with heat-resistant rubber such as silicone rubber, and rotates while being in pressure contact with the heat roll 8 (FIG. 5).

One end of the drive shaft 1 is connected to a drive source through a gear, and the other end is connected to a heat roll 8 through a drive key 13 (FIG. 6).

The driven shaft 12 is press-fitted between a flange 15 of a coupling member that is coupled to the fixing frame 14, a composite bearing 16, a collar 17 of a support member that supports the fixing roll 7, and a collar 1-7 and the composite bearing 16. The fixing roller 7 is composed of a heat insulating material 18 and a spring 19 that presses a composite bearing 16 press-fitted into the flange 15 toward the fixing roll 7 (FIG. 7).

[Problem to be solved by the invention]

As mentioned above, the heat roll rotates while being supported by the moving shaft and the driven shaft, and together with the backup roll heats and presses the toner image transferred to the paper to fix it. In this case, the backup roll is rotated by the pressing means. Since it is pressed in the direction of the heat roll, the heat roll is periodically eccentric, and the composite bearing and the heat insulating material of the driven shaft continue to be periodically subjected to fatigue due to mechanical shock and fatigue due to heat.

Figure 8 shows the operating situation between the heat roll 8 and the driven shaft 12 during opening, and there is a large gap between them due to the difference in thermal expansion and the influence of dimensional tolerances. Figure 9 shows the fatigue curve of the driven shaft, where the horizontal axis shows the number of printed pages Mp (megapages), and the vertical axis shows the composite value S of fatigue due to mechanical loading and fatigue due to heat. When the number of printed pages Mp reached a certain value, the fatigue limit value SQ was suddenly reached, and a phenomenon occurred in which the composite bearing and the heat insulating material were destroyed.

As described above, in the conventional fixing device, (A) the composite bearing and the heat insulating material have a very short lifespan, so the expensive driven shaft has to be replaced in a short period of time;

(B) In order to make effective use of the expensive driven shaft, it was necessary to replace the insulation material and maintain the composite bearing at short intervals.

(C) Since the heat insulating material was press-fitted into the driven shaft, it was extremely difficult to replace the heat insulating material.

An object of the present invention is to provide a fixing device for an electrophotographic machine that is easy to maintain and has a long service life.

[Means to solve the problem]

The present invention includes a heating roll and a pressure roll, and both ends of one of the rolls are connected to a driving shaft and a driven shaft, respectively, and the paper passing between the rolls is heated and pressed to form a toner image. The first aspect of the fixing device of an electrophotographic camera that performs fixing is that a heat insulating material is removably provided on the outside of the driven shaft to absorb fatigue due to mechanical loading and heating that occurs on the driven shaft during operation of the fixing device. A second feature is that plastic is used as the heat insulating material, and the purpose is achieved by providing a fixing device with a long life.

[Effect]

In the fixing device of the electrophotographic machine of the present invention, a heat insulating material is removably attached to the outside of the driven shaft of the heat roll, for example, to absorb mechanical stress and thermal fatigue applied to the driven shaft of the heat roll during operation of the device. Since plastic is used as the material, the fatigue characteristics of the driven shaft are greatly improved, maintenance is simplified, and a long life of the device can be achieved.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. 1st
The figure is an exploded view of a P1-roll showing an embodiment of the fixing device for an electrophotographic apparatus according to the present invention, and FIG. 2 is a sectional view of a heat roll driven shaft. In both figures, the same parts as in FIGS. 5 to 7 are given the same reference numerals. In both figures, 20 is a plastic heat insulating material. As is clear from a comparison with FIG. 7, in FIG. 2, the NB collar 17 is removably attached to the outside of the collar 17. Removable heat-insulating plastic collar 2 meters long
0 (e.g. polyetherimide (Ultem D4001)
(product name)) is attached. This plastic collar 20 makes it possible to reliably absorb stress, mechanical loading and thermal fatigue. Furthermore, the heat insulation effect can be greatly improved compared to the conventional device (FIG. 7).

FIG. 3 shows a fatigue curve diagram of the driven shaft used in this embodiment, in which the horizontal axis represents the number of printed pages Mp, and the vertical axis represents the fatigue value S. Figure 9: Limit fatigue value S compared to (conventional device). It can be seen that which intersection points are significantly extended and the life of the device is significantly extended.

In this way, the heat insulating material 20 of the plastic 7 is attached to the driven shaft 12.
By attaching and detaching it to the outside of the driven shaft, the life of the driven shaft 12 can be extended by three to four times.Furthermore, since the plastic collar 20 can be easily replaced, the fatigue limit value S0 can be reached. If you replace it before, the driven shaft 12
It is possible to extend the service life by 10 to 1-5 times.

Although plastic is used as the material for the heat insulating material in this embodiment, the same effect can be obtained by using metal or ceramics as the material. Also, this insulation material can be applied to locations other than heat rolls that are subject to mechanical and thermal stalls.

〔Effect of the invention〕

As described above, according to the present invention, the following effects can be obtained.

(1) Maintenance of the fixing device can be easily performed.

(2) The life of the driven shaft, and therefore the life of the fixing device, can be significantly extended.

(3) Maintenance costs can be significantly reduced, resulting in great economic effects.

[Brief explanation of drawings]

FIG. 1 is an exploded view of a heat roll showing an embodiment of the fixing device of an electrophotographic machine according to the present invention, FIG. 2 is a sectional view of the driven shaft shown in FIG. 1, and FIG. 3 is a driven shaft shown in FIG. 2. Fig. 4 is a system diagram of an electrophotographic machine, Fig. 5 is a cross-sectional view of a conventional fixing roll, Fig. 6 is an exploded view of the heat roll shown in Fig. 5, and Fig. 7 is a diagram of Fig. 6. 8 is a cross-sectional view of the driven shaft shown in FIG.
FIG. 8 is a fatigue curve diagram of the driven shaft shown in FIGS. 7 is a fixing roll, 8 is a heat roll, 9 is a backup roll, 11 is an opening shaft, 2 is a driven shaft 18. 20 is a heat insulating material. ) 1 figure) 2 figure) 4 figure) 3 figure) 5 figure 0 5 0 [P printing number (gate P) 5・eaves-qylI! 10 Hee 7 Nfu' (S) Force Committee Ne)

Claims (1)

[Claims] 1. A heating roll having a heating element inside, and a pressure roll pressing the heating roll, with both ends of one of the rolls being connected to a driving shaft and a driven shaft, respectively. In an electrophotographic fixing device that heats and presses paper passing between rolls to fix a toner image, a heat insulating material that absorbs mechanical shock and fatigue caused by heating on the driven shaft during operation of the fixing device is provided. A fixing device for an electrophotographic machine, characterized in that the fixing device is detachably provided on the outside of the driven shaft. 2. The fixing device for an electrophotographic machine according to claim 1, wherein the heat insulating material is made of plastic.