JPH07219352A - Magnet roll - Google Patents

Abstract

PURPOSE:To obtain a lightweight magnet roll having high adhesion strength and good wear resistance of the supporting part which can be produced at a low cost by forming a conductive member from the supporting part of the magnet roll to the sleeve so that bias voltage can be stably applied on the nonmagnetic sleeve. CONSTITUTION:This magnet roll consists of a permanent magnet member 1 having <=16mm outer diameter D and axial length L satisfying L/D>=3 and having several magnetic poles on the outer circumferential surface along the axial direction, a sleeve 6 and flanges 3, 4 on both ends of the sleeve 6 so that the roll can be relatively rotated. The sleeve 6 consists of a nonmagnetic material which can be plastically processed and is formed in a hollow cylinder having an annular recessed part on the inner wall of the end. At least one end of the permanent magnet member has a metal shaft 7 and 8. The flange has a supporting part 3a and consists of oil-impregnated powder sintered metal having conductivity. The flange is fitted to the annular recessed part formed on the inner wall of the sleeve end, and the edge of the sleeve is bent inside to engage the sleeve and the flange.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, for example, in electrophotography and electrostatic recording, develops by adsorbing and transporting a magnetic developer from a developer tank to a developing area, or by using a magnetic developer remaining on the surface of an image carrier. The present invention relates to a magnet roll used for adsorbing and removing toner.

[0002]

2. Description of the Related Art Conventionally, many magnet rolls used as a developing roll or a cleaning roll in electrophotography, electrostatic recording and the like have a structure as shown in FIG. In FIG. 4, reference numeral 1 denotes a permanent magnet member, which is often formed of a sintered magnet or a resin magnet mainly for weight reduction. Sintered magnets include, for example, Ba ferrite particles and P
It is prepared by molding a raw material obtained by dry-mixing a binder such as VA by a hydrostatic press (not shown) and subjecting it to a sintering treatment. Alternatively, a raw material in which Ba ferrite particles, water and alcohol are sufficiently mixed is extruded from an extrusion die to be formed into a long shape, both ends are cut into a predetermined axial length, and dried and sintered to be formed into a shape. May be. Then, the outer peripheral surface of the material of the permanent magnet member is subjected to centerless cylindrical grinding to finish the outer diameter of the permanent magnet member 1 to a predetermined size. Next, the shaft 2 whose both ends are reduced in diameter is coaxially fixed to the center of the permanent magnet member 1. On the other hand, in the case of forming a hollow cylindrical permanent magnet member with a resin magnet, as one example, a kneaded material mainly composed of a ferromagnetic powder and a high molecular polymer is injected into a mold in which a shaft is inserted, Injection molding is performed while applying a magnetic field, and the cooled and solidified molded body with shaft is taken out of the mold. As another example, both ends or one end of the permanent magnet member is cut out at a surface intersecting with the periphery of the permanent magnet member to form a supporting portion, and a kneaded product of the resin magnet is formed into a columnar shape which also serves as a shaft. In some cases, the permanent magnet member is formed by injection molding (not shown). Then
By magnetizing in the same direction as the anisotropy, a plurality of magnetic poles (not shown) extending in the axial direction are provided on the outer peripheral surface of the permanent magnet member. Then, on both ends of the shaft 2, flanges 3,
4 is rotatably mounted through bearings 5 and 5 ', and a hollow cylindrical sleeve 6 is fitted to the flanges 3 and 4. The flanges 3 and 4 and the sleeve 6 are made of a non-magnetic material such as aluminum alloy or stainless steel. In the above magnet roll, a permanent magnet member having a relatively small diameter (D ≦ 16 mm) and a length (L) / diameter (D) ratio of 3 or more is used as the resin magnet. Often formed. With the above configuration, the relative rotation between the permanent magnet member 1 and the sleeve 6 (for example, fixing the permanent magnet member and rotating the flange) causes a magnetic developer (for example, a one-component magnetic material) on the outer peripheral surface of the sleeve 6. Toner, or a two-component developer consisting of toner and carrier) is adsorbed to form a magnetic brush,
The predetermined development work is performed.

[0003]

At the time of development, it is necessary to apply a bias voltage to the sleeve in order to prevent background fog or a reversal phenomenon. Therefore, it is usually necessary to form the shaft from a metal material (steel, stainless steel, etc.) so that a new electrode is provided at one end of the shaft so that a current flows through the sleeve through the shaft, the bearing and the flange. Alternatively, there is an inconvenience that a bias voltage must be applied by directly providing an electrode on the non-magnetic sleeve. Therefore, the magnet roll has a large number of parts, a large amount of time and man-hours required for production, and inevitably increases costs. On the other hand, when the permanent magnet member is formed by cutting out both ends or one end of the permanent magnet member to form a support portion and the resin magnet is used to form the permanent magnet member, the metal shaft is not required, and the entire weight can be reduced. However, the weight of the rotating magnet roll must be supported by the support portion of the resin magnet, so that the wear of the support portion is severe when used for a long time. Further, in recent years, the requirements for high reliability and cost reduction have become more and more strict in the developing device, and the above magnet rolls are no exception, and improvements for higher reliability and cost reduction are desired. . The purpose of the present invention is to
By solving the problems existing in the above prior art and providing a conductive member from the magnet roll supporting portion to the sleeve, the bias voltage can be stably applied to the non-magnetic sleeve, and the weight is light and the adhesive strength is high. And
It is an object of the present invention to provide a magnet roll having a support portion with good wear resistance and capable of reducing costs.

[0004]

In order to achieve the above object, the present invention has an outer diameter D whose outer peripheral surface is finished to a predetermined size.
A permanent magnet member having a plurality of magnetic poles extending in the axial direction on the outer peripheral surface with ≤16 mm and an axial length L / D≥3; and a hollow cylindrical shape made of a plastically processable non-magnetic material and having an end portion. A sleeve provided with an annular recess on the inner surface, in a magnet roll configured to be rotatable relative to each other via flanges provided at both ends of the sleeve, at least one end of the permanent magnet member has a short metal shaft, The flange is made of an oil-impregnated powder metallurgical sintered metal (hereinafter simply referred to as oil-impregnated sintered metal) having a supporting portion and conductivity, and the flange is fitted in an annular recess provided on the inner surface of the end portion of the sleeve. We adopted the technical means of bending the ends inward and joining the sleeve and flange. In the present invention,
In the permanent magnet member, it is preferable that the resin magnet has a solid cylindrical shape and the shaft portion is integrally formed, and a metal cap is fitted to the shaft portion.

[0005]

In the magnet roll of the present invention, the flange having the support portion formed at one end is made of the conductive oil-impregnated sintered metal, so that the non-magnetic sleeve is stably provided through the support portion of the flange. A bias voltage can be applied. Further, since the flange is made of the oil-impregnated sintered metal, a separate bearing (ball bearing or oil-impregnated sintered metal bearing) is not required, and the number of parts and the manufacturing cost can be reduced. On the other hand, by attaching a metal cap to the shaft portion of the resin magnet permanent magnet member, it is possible to improve the wear resistance of the support portion.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 3 show an embodiment of the present invention, and the same parts as those in FIG. 4 are designated by the same reference numerals. Figure 1
1A is a vertical cross-sectional view of the material of the permanent magnet member, FIG. 1B is a right side view of the same, FIGS. 2A and 2B are vertical cross-sectional views of the permanent magnet member, and FIG. 3 is a magnet roll. The schematic sectional drawing of is shown. When the permanent magnet member 1 of FIG. 1A is formed of a resin magnet, as an example, a ferromagnetic powder [ferrite,
Rare earth cobalt etc.] and high molecular polymer [polyamide resin (nylon), hard polyvinyl chloride resin, polystyrene resin, polypropylene resin, styrene acrylonitrile resin, ABS resin, polycarbonate resin, polyphenylene resin, polysulfone resin, etc.] Inject the thing into the mold, injection molding while applying a magnetic field,
The cooled and solidified molded body is taken out of the mold. Next, as shown in FIG. 2A, since it is necessary to impart wear resistance to the shafts, the metal short shafts 7 and 8 are recessed into a shape matching the cross section of the metal short shaft. (B) 1a is press-fitted until it hits the bottom of the recessed hole of the permanent magnet member 1 or the metal short shaft is previously inserted into the injection molding die from the beginning so that the ferromagnetic powder and It is also possible to inject a kneaded material of a molecular polymer and injection-mold a resin magnet while applying a magnetic field. Alternatively, as shown in FIG. 2B, the permanent magnet member 1 can be injection-molded with a resin magnet having a solid cylindrical shape and the shaft portions at both ends are integrally formed. In this case, abrasion resistance is imparted. Since it is necessary, the caps 9 and 10 may be fitted to at least one shaft portion of the permanent magnet member. As shown in FIG. 3, after the surface of the permanent magnet member is magnetized in multiple poles, the flange 3 is inserted into the annular recess provided on the inner surface of the end portion of the sleeve 6, and a processing jig is used (see FIG. (Not shown), the sleeve end is bent inward, ie by caulking, to join the sleeve and the flange. Since the fixing strength of the other flange 4 and the sleeve 6 may be relatively small, the magnet roll is assembled by fixing them integrally by interposing an adhesive between them or fixing them by caulking.
Here, the flanges 3 and 4 are made of an oil-containing sintered metal having conductivity, and also have a bearing function. Further, the bias voltage can be applied to the surface of the sleeve 6 through the electrode 11, the supporting portion 3 a of the flange, and the flange 3. The oil-containing sintered metal used in the present invention is a copper-based material (Cu-Sn
Series, Cu-Sn-Pb series, etc., aluminum series materials (Al-Cu-Mg series etc.), iron series materials (pure iron series, Fe-Cu series, Fe-C series, Fe-C-Cu)
System, Fe-Pb-Cu system, etc.) and stainless steel materials. However, iron-based alloys are generally harder than copper-based alloys and have a poor compatibility with shafts, that is, a poor lubrication performance PV value (= product of allowable load P and shaft peripheral speed V) and poor corrosion resistance. The copper-based material is softer than the copper-based and iron-based materials, so the mechanical strength is inferior, and the stainless-based material is more expensive than the copper-based and iron-based materials. It is preferable. The oil supply mechanism when using a porous oil-impregnated sintered metal as a bearing is briefly described. Because of this, the oil that oozes out forms an oil film on the sliding surface, and metal contact between the shaft and bearing is avoided. Further, when the shaft stops, the shaft cools, so that excess oil existing on the sliding surface is again absorbed by the original oil-containing hole by the capillary force. That is, of course, although it is actually necessary to replenish the oil to some extent, the bearing can be used without lubrication without constantly supplying oil from the outside and functionally without risk of seizure.

[0007]

EFFECTS OF THE INVENTION Since the present invention has the structure and operation as described above, the following effects can be obtained. (1) By forming the flange having the support portion at one end with conductive oil-containing powder metallurgy sintered metal, it is possible to stably apply a bias voltage to the sleeve through the support portion of the flange. Becomes Further, since the flange is formed of the oil-impregnated powder metallurgy sintered metal, a separate bearing becomes unnecessary, and accordingly, a step of previously processing the bearing support portion on the flange and then press-fitting and assembling the bearing becomes unnecessary. Therefore, the number of parts can be reduced and the number of steps can be reduced, and the manufacturing cost can be reduced. (2) By attaching a metal cap to the shaft portion of the resin magnet permanent magnet member, it is possible to improve the wear resistance of the support portion.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view (a) and a right side view (b) of a material of a permanent magnet member in an example of the present invention.

FIG. 2 is a vertical sectional view of a permanent magnet member according to an embodiment of the present invention.

FIG. 3 is a schematic sectional view of a magnet roll showing an embodiment of the present invention.

FIG. 4 is a schematic sectional view of a conventional magnet roll.

[Explanation of symbols]

1 permanent magnet member, 2 shafts, 3 and 4 flanges,
3a Flange support, 5, 5'bearing, 6 sleeve,
7,8 Short metal shaft, 9,10 Cap, 11
electrode

Claims (2)

[Claims] 1. A permanent magnet member having an outer peripheral surface finished to a predetermined size and having a plurality of magnetic poles extending in the axial direction and having an outer diameter D ≦ 16 mm and an axial length L / D ≧ 3. A magnet roll comprising a sleeve formed of a nonmagnetic material capable of being plastically processed into a hollow cylinder and having an annular recess on the inner surface of the end thereof, and rotatable relative to each other via flanges provided at both ends thereof. In, at least one end of the permanent magnet member has a short metal shaft, the flange has a supporting portion and is made of an oil-impregnated powder metallurgical sintered metal having conductivity, in the annular recess provided on the inner surface of the end portion of the sleeve. A magnet roll, characterized in that the flange is fitted and the sleeve end is bent inward to join the sleeve and the flange. 2. The permanent magnet member is made of a resin magnet having a solid columnar shape and a shaft portion integrally formed, and a metal cap is fitted to at least one end of the shaft portion. The described magnet roll.