JPH0684463U - Magnetic cylinder - Google Patents

Abstract

(57) [Abstract] [Purpose] Mold release at the time of injection molding is good, and there is no scratch at the time of release.
It is intended to provide a magnetic cylinder using a sleeve integrated body. A magnetic cylinder used in an electrophotographic apparatus, wherein a magnet roll having a plurality of magnetic poles formed on the outer peripheral surface is rotatably housed inside a sleeve whose ends are closed by flanges. The structure is such that the magnet rolls have different diameters, and the magnet rolls having different outer diameters at both ends are also incorporated, so that the distance between the inner circumference of the sleeve and the outer circumference of the magnet roll is constant in the length direction of the magnetic cylinder. .

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a magnetic cylinder used in a dry electrophotographic system such as a copying machine, a facsimile, and a laser beam printer.

[0002]

[Prior art]

 A magnetic cylinder as shown in FIG. 4 is used in a developing device of a copying machine or a facsimile. In this magnetic cylinder, a cylindrical sleeve s usually made of a non-magnetic material is provided on the outside of a magnet roll M composed of shafts a and b protruding from both end surfaces of a cylindrical magnet having a plurality of magnetic poles. Both ends are sealed with flanges c and d, and are rotatably supported by a shaft a projecting from one end of the magnet roll M, and a shaft b projecting from the other end is penetrated through the flange d. The shaft b is fixed and supported by projecting it to the outside of the sleeve s, so that the magnet roll M is internally provided in the sleeve s in a non-contact state. By rotating the magnet roll M with respect to the sleeve s, the toner made of a magnetic material is magnetically attracted to the surface of the sleeve s, and the toner is regulated to a constant thickness by the developer passage amount regulating plate, and is formed on the photosensitive drum. It is transferred onto the electrostatic latent image.

On the other hand, when manufacturing the above-mentioned developing cylinder, as shown in FIG. 5, one flange and the sleeve are integrally molded with a vibration absorbing resin or the like to reduce the number of parts and further reduce the manufacturing cost. The applicant of the present invention has proposed a magnetic cylinder that reduces the vibration generated when the magnet roll M rotates. In this case, a magnet roll M is incorporated in a flange / sleeve integrated body e and the opening end is sealed by a flange f.

[0004]

[Problems to be solved by the device]

 As described above, manufacturing one flange and the sleeve by integral molding is effective in reducing the manufacturing cost by reducing the number of parts. However, since it is necessary to perform the molding simultaneously, it is necessary to perform the molding. In some cases, the releasability from is a problem. That is, when a processed product is removed from the mold in injection molding, for example, if a minute scratch is present on the inner surface of the mold, a marked scratch will be left on the molded product. However, on the surface of the magnetic cylinder, fine particles of toner must be carried on the surface in a uniform concentration, so even a minute scratch will seriously affect the image. Therefore, by manufacturing one flange and the sleeve by integral molding, the manufacturing cost is reduced by reducing the number of parts, and the separation that is typical of the occurrence of minute scratches due to the use of injection molding is achieved. Due to the problem of moldability, the production yield of magnetic cylinders was reduced.

[0005]

[Means for Solving the Problems]

 The present invention has been devised in view of the above-mentioned problems, and uses a sleeve or a flange / sleeve integrally molded body that improves the mold release during injection molding and prevents scratches during release. The magnetic cylinder that was used. The present invention, which has solved the above-mentioned problems, is a magnetic cylinder used in an electrophotographic apparatus, in which a magnet roll having a plurality of magnetic poles formed on its outer peripheral surface is rotatably housed inside a sleeve whose ends are closed by flanges. In addition, the outer diameter of both ends of the sleeve may be different, or a magnet roll with different outer diameters at both ends may be installed inside, and the distance between the inner circumference of the sleeve and the outer circumference of the magnet roll may be set in the length direction of the magnetic cylinder. Is constant in.

[0006]

[Action]

 In the magnetic cylinder of the present invention, the outer diameter of both ends of the sleeve is made different as described above, so that the outer circumference of the sleeve is inclined. This gradient becomes the die release taper for mold release during injection molding.

[0007]

【Example】

 Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an example of a magnetic cylinder according to an embodiment of the present invention as an explanatory sectional view. In the example shown in the figure, the sleeve SL and the one flange portion 1 are integrally molded so that the outer diameter and inner diameter of both ends are different to form a flange / sleeve integrally molded body 2. Similarly, the outer diameters of both end portions are the same. A different magnet roll M is installed inside, and the opening end is sealed by the other flange 3 so that the magnet roll M can be rotated with respect to the flange / sleeve integrated body 2. Here, the difference between the outer diameter and the inner diameter of the both ends of the flange / sleeve integrally molded body 2, that is, the gradient which acts as a die release taper for mold release at the time of injection molding is set to 2 °. Also, with respect to the magnet roll M, the gradient due to the difference in outer diameter at both ends is set to 2 °, which is the same as the draft taper, and the inner peripheral portion of the flange / sleeve integrated molded body 2 and the outer peripheral portion of the magnet roll M are arranged in the length direction. The gap was kept constant. The magnetic cylinder shown in FIG. 1 can be manufactured by the following steps, for example.

The flange and the sleeve were made into a pellet of a Seider made by Nippon Petrochemical Co., Ltd., which is a main chain polyester liquid crystal polymer containing 30% by volume of atomizer silver powder having a particle size of 3 μm, and injection was performed at a molding temperature of 370 ° C. By integrally molding by molding, a flange / sleeve integrated molded body 2 of which one side is sealed is obtained. The slope for draft taper of the flange / sleeve integrated body 2 is 2 °. Due to this gradient, the mold can be released from the mold without leaving a significant scratch on the surface of the integrally molded body 2. Subsequently, a magnet roll M penetrating a stainless shaft is bonded to a bonded magnet having a slope 2 ° similar to that of the flange / sleeve integrated body 2 through a rolling bearing 4 and an opening at one end is provided. The flange 3 made of the same liquid crystal polymer material and the same manufacturing method can be used to seal and fix with an epoxy conductive adhesive to obtain a magnetic cylinder as shown in FIG. Here, an example of a magnetic cylinder having conductivity is shown in consideration of applying a voltage to the magnetic cylinder at the time of development, but if a voltage is not applied, the conductive dispersion material is not added. It's okay. Besides the above materials, engineering plastic materials such as polyacetal can also be used.

On the other hand, it is conceivable that only the sleeve SL is made of synthetic resin by injection molding instead of the conventional metal sleeve. In this case as well, as in the above embodiment, the outer diameters at both ends are as shown in FIG. Different sleeves SL may be used, and both ends may be sealed with the flanges 3 and 5.

Further, in order to further improve the toner carrying property, it is also an idea to provide fine irregularities on the surface by blasting or fine grooves by cutting.

Since the magnetic cylinder of the present invention as described above has different outer diameters at its both ends, the positional relationship with the photosensitive drum is different from the conventional one, as shown in FIG. In the example shown in the figure, the photosensitive drum D is installed so as to be inclined so that the gap between the magnetic cylinder G and the photosensitive drum D is constant in the lengthwise direction. Although this figure uses a photosensitive drum, a sheet-shaped or belt-shaped photosensitive member can also be used.

[0012]

[Effect of device]

 As described above, according to the magnetic cylinder of the present invention, the outer diameters of the both ends of the sleeve are made different so that a gradient is provided on the outer circumference of the sleeve, and this gradient is used as a die release taper for mold release during injection molding. No scratches will occur during molding. Therefore, even a flange / sleeve integrated body can be manufactured with high yield, which can contribute to a reduction in the manufacturing cost of the magnetic cylinder.

[Brief description of drawings]

FIG. 1 is an explanatory sectional view showing the structure of a magnetic cylinder according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the structure of a magnetic cylinder according to another embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a positional relationship between a magnetic cylinder of the present invention and a photosensitive drum.

FIG. 4 is an explanatory sectional view showing the structure of a conventional magnetic cylinder.

FIG. 5 is a cross-sectional explanatory view showing a structure when one flange and a sleeve are integrally molded in a conventional magnetic cylinder.

[Explanation of symbols]

 1 Flange portion 2 Flange / sleeve integrated body 3 Flange 4 Rolling bearing 5 Flange D Photosensitive drum G Magnetic cylinder M Magnet roll SL, s Sleeve a, b Shaft c, d, f Flange e Flange / sleeve integrated body

Claims (2)

[Scope of utility model registration request] 1. A magnetic cylinder for use in an electrophotographic apparatus, wherein a magnet roll having a plurality of magnetic poles formed on its outer peripheral surface is rotatably housed in a sleeve whose both ends are closed by flanges. A magnetic cylinder characterized by different outer diameters. 2. A magnetic cylinder according to claim 1, wherein magnet rolls having different outer diameters at both ends are internally provided, and the distance between the inner circumference of the sleeve and the outer circumference of the magnet roll is constant in the length direction of the magnetic cylinder.