JPS63293575A - Fixing device in electrophotographing device - Google Patents

Abstract

PURPOSE:To suppress the destruction of a key groove part due to the pression of a key and to extend the life of a fixing roll by fitting a cushioning material for a drive key to the key groove part of a fixing roll. CONSTITUTION:The cushioning material 16 obtained by working a stainless steel plate capable of resisting sliding abrasion and having high rigidity like a U-shape with ears is fixed on the sides of the key groove part 13 on the end part of at least one fixed roll out of a pair of fixing rolls 8 for heating and fixing a toner image on a supporting body by mutually pressing against each other. At the time of engaging the drive key on the driving force transmission shaft side with the key groove part 13, transmitting driving force and executing heating and fixing, the point contact pressure of the drive key is diffused to face pressure in a fixed range by the cushioning material 16 and sliding abrasion resistance between the drive key and the key groove part 13 is sharply reduced. Thereby, the life of the fixing roll can be extended and maintenance cost can be sharply reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a heat fixing roll in a fixing device of an electrophotographic apparatus.

[Background of the invention]

In an electrophotographic apparatus such as an electrophotographic printing apparatus shown in FIG. 4, a photosensitive member 2 whose surface is uniformly charged by a charger is used.
is irradiated with light 3 such as a laser beam to form an electrostatic latent image,
Toner is supplied to this by the developing device 4, and development is performed. Next, the toner is transferred to a paper 6 by a transfer device 5, preheated by a heating plate 7, and completed fixing while heating the paper by a set of heat-pressure fixing rolls 8 each having one heating roll. In FIGS. 5 and 6, at least one of the fixing rolls 8 has a heater lamp 11 detachably attached to the center thereof, and is an aluminum roll made of A3052 or the like with good thermal conductivity and whose surface is coated with a non-adhesive resin such as Teflon. The driving force transmission shaft 9
The fixing roller is driven through a drive key 10 made of hardened carbon steel or the like having a hardness of HRC 30 to 50, and the toner image is fixed while the two fixing rolls are brought into contact with each other under heat and pressure.

Conventionally, if the key groove section 13 provided at the end of the fixing roll 8 continues to receive the driving force from the drive key 10 for a long time, it will break due to heat and fatigue when the amount of printed pages reaches a certain number of pages. was occurring.

The process of breaking the keyway portion of the fixing roll will be explained using FIG. In the fixing roll 8 that rotates while being heated and pressurized, a gap 14 is created between the fixing roll 8 and the driving force transmission shaft 9 due to the difference in thermal expansion and dimensional tolerance. When a pair of press-contacted fixing rolls is driven by the driving force transmission shaft 9 via the drive key 1o, the driving force transmission shaft 9 is pressed in the direction of the other fixing roll by a suppressing means (not shown). The movement of the key 10 relative to the keyway portion 13 is a kind of sliding motion accompanied by radial sliding as shown in A→B−+CnD.6 Because the keyway portion in a normal power transmission unit deforms and breaks due to the contact pressure of the key. It is only necessary to consider the compressive strength, but in the case of a fuser roll that rotates under pressure to avoid thermal deformation as described above, it is not only possible to break due to surface pressure, but also to cause the key to "slide" relative to the key groove. It became clear that failure due to sliding wear was a major cause of failure. In this case, the following problems occur.

(1) Because the key groove breaks down much faster than in a normal drive system, the fuser roll is an expensive fuser roll whose surface has been subjected to high-precision Teflon grinding processing, even though the heat-conductive pressure contact member still has some lifespan. I have no choice but to replace it.

(2) When the key groove is destroyed and rattling occurs, especially in high-speed electrophotographic equipment, there is a time lag between the amount of paper fed by the paper feed tractor and the amount of paper pulled by the fixing roll, resulting in transfer in the transfer unit. Printing defects occur due to misalignment. Further, rotational deviation occurs between the upper fixing roll and the lower fixing roll in the fixing section, resulting in printing defects.

(3) Destruction of the keyway portion causes noise between it and the drive portion.

[Purpose of the invention]

An object of the present invention is to solve the above-mentioned drawbacks of the conventional example, and to provide an electrophotographic apparatus having a fixing roll which rotates under pressure without causing thermal deformation, and which has a length far longer than the conventional example that enables stable transmission of driving force. Our goal is to provide a fuser roll with a long lifespan.

[Summary of the Invention] The present invention provides a fixing device for an electrophotographic apparatus that has a pair of fixing rolls and drives at least one of the fixing rolls by a drive transmission shaft having a drive key. By providing a cushioning material against the key groove, damage to the key groove due to the sliding movement of the key can be prevented.
This is intended to significantly extend the life of the fixing roll.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the invention. In the figure, a cushioning material 15 is embedded in the side surface of the key groove portion 13 at the end of the fixing roll 8. In FIG. 2, the key groove portion 13 of the fixing roll 8 is made of SU with a thickness of 0.5 m that is resistant to sliding wear and has high rigidity.
A cushioning material 16 made of a stainless steel plate processed into a U-shape with ears is fixed.

The cushioning material 16 diffuses the point contact pressure of the drive key 10 into a surface pressure within a certain range, and the sliding friction resistance between the drive key 10 and the keyway 13 is significantly reduced. FIG. 3 shows the relationship between the wear amount and time of the keyway portion of the fixing roll of the present invention and the conventional fixing roll. As is clear from FIG. 3, the allowable limit wear amount ε of the keyway. The time required for the fixing roll of the present invention to reach this point is two to three times longer than that of a conventional fixing roll.

In this embodiment, stainless steel was used as the buffer material, but other steel materials or metals, various engineering plastics, etc. with appropriate hardness and slip characteristics can be used. The cushioning material may be fixed to the keyway by press-fitting it into the end using its elasticity, or by gluing, caulking, screwing, or other methods. Further, the key groove portion may be coated with a suitable buffer material.

〔Effect of the invention〕

As described above, the present invention provides a buffer material in the key groove portion of the fixing roll to prevent damage to the key groove portion of the fixing roll. It is possible to almost completely eliminate the problem of printing defects in the system. Furthermore, it is possible to dramatically extend the life of the expensive fixing roll and significantly reduce maintenance costs. Further, it has a practical effect of completely eliminating the generation of noise due to destructive deformation of the keyway portion.

[Brief explanation of drawings]

FIG. 1A is a side view showing an embodiment of the present invention, and FIG. 1B is a plan view thereof. FIG. 2 is a perspective view showing an embodiment of the present invention. FIG. 3 is a graph showing the life of the fixing roll of the present invention. FIG. 4 is a schematic diagram of a conventional electrophotographic printing apparatus, and FIG. 5 is a longitudinal sectional view showing a conventional fixing roll. FIG. 6 is a perspective view showing the drive section. FIG. 7 is a schematic diagram showing a key groove wear process in a fixing roll that is heated and pressurized. 8: Fixing roll 9: Driving force transmission shaft 10 Drive key 13: Key groove portion 15. 16: Cushioning material Name of patent applicant Hitachi Koki Co., Ltd. Figure 5 Figure 6 Figure 13 Figure 7 ■-111■ □O□■ Procedural amendment (formality) August 26, 1988 Director-General of the Patent Office
``1 Indication of the case Patent Application No. 129297 of 19882 Title of the invention Fixing device in an electrophotographic device 3 Relationship with the case of the person making the amendment Patent applicant address 2-6-2-4 Otemachi, Chiyoda-ku, Tokyo Date of amendment order: July 28, 1988 or later

Claims (1)

[Scope of Claims] 1. An electronic drive force transmitting shaft is engaged with the end of at least one of a pair of fixing rolls that heat and fix the toner image on a support by being in pressure contact with each other to drive the fixing roll. In a fixing device for a photographic apparatus, a key groove portion is provided at the end of the fixing roll, a drive key that engages with the key groove portion is provided on the driving force transmission shaft, and the key groove portion provides contact pressure and slip resistance generated by the drive key. A fixing device for an electrophotographic apparatus, characterized in that it is provided with a cushioning material that reduces the amount of noise. 2. A fixing device in an electrophotographic apparatus according to claim 1, characterized in that a thin metal material is used as the cushioning material. 3. A fixing device in an electrophotographic apparatus according to claim 2, characterized in that a stainless steel plate is used as a buffering agent. 4. The fixing device in an electrophotographic apparatus according to claim 3, wherein a stainless steel plate having a thickness of 0.5 to 1.0 mm is used as the buffer. 5. At both ends of the fixing roll, approximately 1 point relative to the center of the roll
2. The fixing device for an electrophotographic apparatus according to claim 1, wherein key groove portions are provided at positions facing each other at an angle of 80 degrees, and a cushioning material is provided in each key groove portion. 6. A fixing device in an electrophotographic apparatus according to claim 1, characterized in that a plastic material is used as the cushioning material.