JPH0419765Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnet roll used for development in electrophotography, electrostatic recording, etc.

[Conventional technology]

As shown in FIG. 5, in a conventional magnet roll, a shaft 2 is fixed to the center of a permanent magnet 1 made of hard ferrite with a circular cross section, and a plurality of magnetic poles are provided on the surface of the permanent magnet 1. .
Support members 3 and 4 are rotatably mounted on both ends of the shaft 2 via bearings 5 and 5.
4 is fitted with a sleeve 6. The support members 3, 4 and the sleeve 6 are made of a non-magnetic material such as aluminum alloy or stainless steel. A sealing member 7 is fitted between the support member 3 and the shaft 2. The magnet roll configured as described above has a shaft 2 and support members 3 and 4.
By the relative rotation between the permanent magnet 1 and the sleeve 6, the developer is attracted onto the sleeve 6 to form a magnetic brush, and a predetermined developing operation is performed.

[Problem that the invention attempts to solve]

The magnet roll with the conventional structure as described above has many parts, namely, a permanent magnet 1, a shaft 2, supporting members 3, 4, bearings 5, 5,
Since it is composed of the sleeve 6, the seal member 7, etc., assembly is complicated, and the time and man-hours required for processing and assembly are large. Therefore, there are problems of low productivity and high costs, and in particular in recent years, there has been a tendency for sleeves with outer diameters of 25 mm or less to be frequently used, so the above problems have been brought into focus.

The object of the present invention is to solve the above-mentioned problems with the conventional magnet rolls, and to provide a magnet roll that is particularly suitable for small-diameter sleeves with an outer diameter of 25 mm or less.

[Means for solving problems]

In order to solve the problems existing in the above-mentioned prior art, in the present invention, A. sliding bearings are arranged at both inner ends of a sleeve made of a non-magnetic material and formed into a thin hollow cylindrical shape.

B. A flange with a shaft projecting outward is fixed to one end of the sleeve.

C. A solid cylindrical permanent magnet is inserted and supported between the slide bearings so as to be rotatable relative to the sleeve.

D. A plurality of magnetic poles are arranged on the surface of the permanent magnet in a range corresponding to the effective development width.

This technical method was adopted.

[Effect]

With the above configuration, the permanent magnet and the sleeve can rotate freely relative to each other via the sliding bearing, so that the developer can be attracted onto the sleeve to form a magnetic brush and a predetermined developing operation can be performed.

〔Example〕

FIG. 1 is a longitudinal cross-sectional view with the middle part omitted, showing an embodiment of the present invention. In the figure, 11 is a sleeve, made of the same non-magnetic material as before, with a wall thickness of 0.5~
Form into a 1.5mm thin hollow cylinder. The cylinder diameter is usually 25mm or less. Sleeve 11
A flange 13 with a shaft 12 projecting outward is fixed to one end of the flange 13. The means for fixing the sleeve 11 and the flange 13 is, for example, cold forging called coining, which will be described later. Note that the material constituting the flange 13 and the shaft 12 is a non-magnetic material similar to the sleeve 11. Next, sleeve 11
Sliding bearings 14 and 15 are provided at both inner ends of the shaft. The sliding bearings 14 and 15 are made of a self-lubricating material such as polyacetal, tetrafluoroethylene, or Delrin, and have a wall thickness of 0.3 to 0.5 mm.
6 to ensure a gap between the two. Note that the sliding bearing 14 installed on the flange 13 side is in the form of a blind hole, but the sliding bearing 15 installed on the other side is
It is preferable to provide a through hole. Next, a permanent magnet 16 is formed into a solid cylindrical shape and is inserted and supported between the sliding bearings 14 and 15, and is supported by the sleeve 11.
and can be rotated freely. Therefore, between the permanent magnet 16 and the sleeve 11, the sliding bearings 14 and 15 are provided.
A gap equivalent to the wall thickness is formed. Permanent magnet 1
6 is an oxide permanent magnet whose outer peripheral surface is ground after being formed by extrusion or rubber pressing, for example;
Or a bonded magnet (by injection molding, extrusion molding, etc.) in which magnetic powder is bonded with an organic polymer such as plastic.
It can be done. Next, as shown in FIG. 2, a plurality of magnetic poles 17 are provided on the outer surface of the permanent magnet 16 within an effective development width l. The illustrated example shows an example in which three poles of S, N, and S are provided asymmetrically.

With the above configuration, the permanent magnet 16 and the sleeve 1
1 can be rotated relative to each other via the sliding bearings 14 and 15, so that a predetermined developing operation can be performed as described above.

FIG. 3 is a diagram showing means for displaying the magnetic pole position on the end face portion of the permanent magnet 16. In other words, regarding the developing operation, in a developing method in which the permanent magnet 16 is fixed and only the sleeve 11 is rotated, it is necessary to accurately oppose the developing magnetic pole to the photosensitive drum (not shown). must be displayed. First, FIG. 3a shows an example in which an arrow 18 is provided on the end face of the permanent magnet 16 to indicate the position of the north pole, for example. The arrow 18 may be a stamp or may be a coating of paint that does not disappear easily. Next, FIG. 3b shows an example in which a marking magnetic pole 19 is provided on the outer peripheral surface of the end of the permanent magnet 16, and FIG. 3c shows an example in which a marking magnetic pole 20 is provided on the end surface of the permanent magnet 16. be.

Next, Fig. 4 a and b show the sleeve 11 and flange 1.
FIG. 3 is a partial vertical cross-sectional view showing an example of a means for fixing the device to the device. In both figures, first a raw tube 11 made of a non-magnetic material such as aluminum alloy or stainless steel is shown.
After cutting a into a predetermined length, it is annealed to improve plasticity and coated with a lubricant. Next, the flange 13 provided with the groove 13a on the outer periphery is attached to the base pipe 11.
4A as shown by the arrow in FIG. 4A, and set, for example, in a mold (none of which is shown) attached to a hydraulic press device. Shaft 1 of flange 13
By ironing the outer peripheral surface of the raw pipe 11a while supporting the second end face, a part of the raw pipe 11a is bitten into the groove 13a of the flange 13 while reducing the wall thickness of the raw pipe 11a. As a result, the sleeve 11 and the flange 13 can be fixed and integrated as shown in FIG. 4b. The above method is one of the known cold forging methods commonly referred to as coining. It should be noted that the sleeve 11 and the flange 13 can be joined together by means other than the coining described above, and they can also be formed by cold integral forging.

In this embodiment, an example was shown in which the permanent magnets were formed to have the same diameter, but the effect is the same even if the part that protrudes after being combined with the sleeve is made smaller in diameter. Furthermore, it is naturally possible to arbitrarily set the number of magnetic poles disposed on the outer surface of the permanent magnet, and to make the magnetic pole arrangement symmetrical or asymmetrical. Further, the sliding bearing may be formed at a predetermined position on the surface of the cylindrical permanent magnet by means of coating or the like.

[Effect of idea]

Since the present invention has the structure and operation described above, the number of parts is extremely small and manufacturing is easy. In addition, because the conventionally shaped bearings are arranged, it is possible to make effective use of both ends, where it was impossible to make effective use of permanent magnets, making it ideal for downsizing, especially for small-diameter magnets with sleeve outer diameters of 25 mm or less. This structure is ideal for nettrol. Therefore, the time and man-hours required for processing and assembly can be significantly reduced, and productivity can be improved.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view with the middle part omitted showing an embodiment of the present invention, Fig. 2 is a perspective view with the middle part omitted showing the permanent magnet in Fig. 1, and Figs. 3 a to c show the ends of the permanent magnet. FIGS. 4a and 4b are partial vertical cross-sectional views showing an example of fixing means between the sleeve and the flange, and FIG. 5 is an intermediate section showing a conventional magnet roll. It is an abbreviated longitudinal cross-sectional view. 1, 16... Permanent magnet, 6, 11... Sleeve, 14, 15... Slide bearing.

Claims (1)

[Claims for Utility Model Registration] (1) A sleeve made of non-magnetic material and formed into a thin-walled hollow cylinder, with sliding bearings arranged at both inner ends thereof,
A flange having a shaft protruding outward is fixed to one end of the sleeve, and a permanent magnet formed in the shape of a solid cylinder is inserted and supported between the sliding bearings so as to be rotatable relative to the sleeve. A magnet roll characterized in that a plurality of magnetic poles are arranged on the surface of a permanent magnet in a range corresponding to the effective development width. (2) The magnet roll according to claim 1, wherein the permanent magnet is an oxide permanent magnet or a bonded magnet in which magnetic powder is bonded with an organic polymer. (3) The magnet roll according to claim 1 or 2 of the utility model registration claim, in which a sliding bearing is fixed to a solid cylindrical permanent magnet side.