JPH0636062U - Magnetic cylinder - Google Patents

Abstract

(57) [Summary] [Object] To provide a magnetic cylinder used in an electrophotographic apparatus, which does not require a spacer for securing a gap with a photoconductor or an adhesive for fixing a sleeve and a flange. It is something to do. [Structure] In a magnetic cylinder used in a dry electrophotographic apparatus, in which a magnet roll having a plurality of magnetic poles formed on its outer peripheral surface is rotatably housed in a cylindrical sleeve whose both ends are closed by a flange, An annular groove is provided, and the annular groove and the sleeve are fitted together.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a magnetic cylinder used in a copying machine, a facsimile machine, an electrophotographic developing device such as a laser beam printer, and a cleaning device.

[0002]

[Prior art]

 Fig. 5 shows an axial sectional view of a magnetic cylinder used in a developing device or a cleaning device of a copying machine or a facsimile machine, in which a metal sleeve is mounted on a magnet roll. On the outside of the magnet roll M provided with shafts 1 and 2 projecting from both end surfaces of a cylindrical magnet having a plurality of magnetic poles, a cylindrical sleeve SL which is usually made of a non-magnetic material and has conductivity is provided as an exterior. Both ends are sealed with the flanges 3 and 4, and the shaft 1 protruding from one end of the magnet roll M is rotatably supported, and the shaft 2 protruding from the other end is passed through the flange 4. The magnet roll M is internally housed in the sleeve SL in a non-contact state by projecting it out of the sleeve SL and fixing and supporting the shaft 2. By rotating the sleeve SL with respect to the magnet roll M, the developer made of a magnetic material is magnetically adsorbed on the surface of the sleeve SL, and the developer passage amount regulating plate controls the thickness to a certain value. It is transferred onto the formed electrostatic latent image.

[0003]

[Problems to be solved by the device]

 Since the fitting part of the flange to the sleeve also serves as a power transmission part to the sleeve, it must be firmly fixed to the inner peripheral surface of the sleeve. For this reason, it is considered to press-fit the flange with the outer diameter of the fitting portion slightly larger than the inner diameter of the sleeve to be fitted into the sleeve, but in such a method, as shown in FIG. It is not preferable because there is a problem that the end of the sleeve swells. For this reason, usually, a method has been generally adopted in which the outer diameter of the flange is set to be approximately equal to or slightly smaller than the inner diameter of the sleeve, and the adhesive is firmly bonded.

However, the use of the adhesive has the following problems. The adhesive is usually an insulator in the cured state, and when a voltage is applied to the sleeve together with the fact that an adhesive layer is uniformly formed on the fitting part to firmly bond the flange and the sleeve. There was a problem that electrical connection between the sleeve and the flange was lost and sufficient voltage was not applied to the sleeve.

On the other hand, when the magnetic cylinder is attached to the electrophotographic apparatus, a resin ring spacer 15 is fitted into the sleeve SL as shown in FIG. 3 in order to secure a constant gap between the magnetic cylinder and the photoreceptor. As a result, manufacturing costs have risen and man-hours have increased.

[0006]

[Means for Solving the Problems]

 The present invention has been made to solve the above problems, and provides a magnetic cylinder that does not require a spacer for securing a gap between a cylinder and a photoconductor or an adhesive for fixing a sleeve and a flange. The roller is used in an electrophotographic apparatus in which a magnet roll having a plurality of magnetic poles formed on the outer peripheral surface is rotatably mounted inside a cylindrical sleeve whose both ends are closed by flanges. In the magnetic cylinder, the flange is provided with an annular groove, and the annular groove and the sleeve are fitted together.

[0007]

[Action]

 In the magnetic cylinder of the present invention, the outer diameter of the flange is larger than the outer diameter of the sleeve because the sleeve is fitted in the annular groove formed in the flange, and the step difference between the sleeve and the flange functions as a substitute for the spacer used in the past. . Further, since the contact area between the sleeve and the flange is about twice as large as that in the conventional case, sufficient fitting strength can be obtained without using an adhesive, even if strong press-fitting is required unlike in the conventional case.

[0008]

Embodiment Next, an embodiment of the present invention will be described. In the present invention, the flange is provided with an annular groove into which the sleeve end can be fitted, and the conventional material can be used as it is. Engineering plastics such as polyacetal and ABS resin are used as the flange material, and non-magnetic metal such as aluminum or stainless steel, or engineering plastics like the flange can be used as the sleeve material. When the sleeve is made of plastics, a conductive dispersant to which carbon black, graphite or the like is added in an appropriate amount, or a surface provided with a layer of a conductive substance is preferable.

As described above, according to the present invention, the contact area between the sleeve and the flange is about twice as large as that in the conventional case, and sufficient fitting strength can be obtained without using an adhesive. It should be set so that the valve can be easily press-fitted. On the other hand, the fitting strength between the sleeve and the flange naturally varies depending on the material, but the depth of the annular groove may be mainly changed so as to obtain a desired fitting strength.

FIG. 1 is a perspective view of a flange according to the present invention, and FIG. 2 is a sectional view when the flange is fitted. The sleeve SL is fitted in the annular groove 11 provided in the flange 10, and as shown in FIG. 2, the step t between the sleeve SL and the flange 10 functions as the same function as a spacer used conventionally. , Secure a gap between the photoconductor and the photoconductor.

As a first example, in consideration of the case where a voltage is applied as a flange material, a molded product is produced by injection molding using a polyacetal resin containing 30% by volume of carbon black having a particle size of 3 μm to 5 μm, A magnetic cylinder was manufactured by incorporating a magnet roll and fitting an aluminum sleeve without using an adhesive. The fitting strength between the flange and the sleeve was comparable to that when using the adhesive in the prior art. As a second embodiment, a polyacetal resin containing 30% by volume of carbon black having a particle diameter of 3 μm to 5 μm, which was used in the first embodiment, was used for both the sleeve and the flange. The sleeve was extruded and the flange was used for the first embodiment. A molded product was produced by injection molding in the same manner as in the above example. A magnetic cylinder was manufactured by incorporating a magnet roll and fitting without using an adhesive, and the fitting strength between the flange and the sleeve was examined. In this example, as in the first example, a fitting strength comparable to that of the conventional product was obtained.

In both of the above two examples, the step t between the sleeve and the flange shown in FIG. 2 was set to be 0.5 mm. Therefore, the wall thickness between the annular groove and the outer peripheral portion of the flange is 0. Although it was 5 mm, no distortion or dimensional deviation was observed in the fitted state.

Although only one flange is described in these embodiments, it goes without saying that the same can be applied to the other flange through which the shaft of the magnet roll penetrates.

[0014]

[Effect of device]

 As described above, in the present invention, since the flange is provided with the annular groove, the gap between the outer peripheral portion of the sleeve and the outer peripheral portion of the flange keeps the gap with the photoconductor constant, so that a spacer as in the past is not necessary. The parts cost can be reduced and the assembly man-hour can be shortened. Further, since the contact area between the sleeve and the flange is approximately doubled, sufficient fitting strength can be obtained by simply press-fitting the sleeve. As a result, no adhesive is required, and there is no electrical failure between the sleeve and the flange, and the manufacturing cost can be reduced. As described above, according to the present invention, the number of parts and the manufacturing cost can be reduced and an inexpensive magnetic cylinder can be realized by the simple method of forming the groove on the flange.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a flange used in the magnetic cylinder of the present invention.

FIG. 2 is an explanatory view showing a state in which the flange of the embodiment is fitted with a sleeve.

FIG. 3 is a cross-sectional explanatory view showing a mounted state of a spacer for securing a gap with a photoconductor in a conventional magnetic cylinder.

FIG. 4 is a cross-sectional explanatory view showing a state in which a flange having a fitting portion having an outer diameter slightly larger than the inner diameter of the sleeve is strongly pressed into the sleeve in the conventional magnetic cylinder.

FIG. 5 is an axial sectional view showing a conventional magnetic cylinder.

[Explanation of symbols]

 1, 2 Shaft 3, 4 Flange 10 Flange 11 Annular groove 15 Spacer M Magnet roll SL Sleeve t Step

Claims (1)

[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 cylindrical sleeve whose both ends are closed by flanges. A magnetic cylinder, characterized in that an annular groove is provided in the sleeve, and the annular groove and the sleeve are fitted together.