JP3850506B2 - Magnet roll - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a magnet roll incorporated in a copying machine, a facsimile, a laser printer, or the like.
[0002]
[Prior art]
2. Description of the Related Art A developing device and a cleaning device incorporated in an electrophotographic copying machine, a facsimile machine, and a laser printer use a magnetic cylinder in which a magnet roll is incorporated in a cylindrical sleeve so as to be relatively rotatable.
The magnet roll is configured by arranging magnets around the shaft. For example, as shown in FIG. 3, sticking magnets b1, b2, b3, and b4 attached to the square surface of the square shaft a with an adhesive or the like. The type is known. Which of the cylindrical sleeve and the magnet roll incorporated so as to be rotatable relative to each other depends on the development method. For example, the magnetic pole formed on the magnet roll has a development pole, a regulation pole, a transport pole, and a collection pole. In the case where each has a unique function, a structure is adopted in which the magnet roll is a fixed side and the cylindrical sleeve is rotated with respect to the magnet roll.
[0003]
[Problems to be solved by the invention]
In a magnetic cylinder with such a structure, in order to make each magnetic pole work as designed, it is necessary to accurately place each magnetic pole, and each magnetic pole has an angle as designed in the direction around the shaft axis. The position needs to be accurately positioned, and this angle must not vary in the longitudinal direction of the axis.
[0004]
However, in the conventional magnet roll, a soft resin magnet having a Vickers hardness of less than 20 is used for the bar-shaped magnet pieces b1, b2, b3, and b4. The linearity in the longitudinal direction of the shaft was poor, and as shown in FIG. 3, a phenomenon in which the bar-shaped magnet piece b bonded to the square shaft a meandered was observed. Therefore, the magnetic pole position differs by 3 ° or more in the axial length direction due to the meandering of the rod-shaped magnet piece b, resulting in variations in the developer conveyance amount in the axial length direction and causing defective images.
[0005]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a magnet roll that solves the problems of the prior art as described above, eliminates variations in the magnetic pole position in the longitudinal direction of the shaft, and provides a good image. .
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a magnet roll of the present invention is a magnet roll in which a plurality of bar-shaped magnet pieces are fixedly arranged around a square shaft, and a Vickers hardness of 20 to 100 around the square shaft. A magnet piece made of a hard resin magnet is arranged, and a magnet piece made of a soft resin magnet having a Vickers hardness of less than 20 is arranged adjacently along the magnet piece .
[0007]
In addition, it is preferable that at least one magnet piece made of the semi-rigid resin magnet is arranged on an important pole around a square shaft, and that the semi-rigid resin magnet has a Vickers hardness of 30 to 60 is preferable. .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying a magnet roll of the present invention will be described below with reference to the accompanying drawings.
1 and 2 relate to a magnet roll according to a typical embodiment of the present invention.
[0009]
As shown in FIG. 1 and FIG. 2, the magnet roll A has rod-shaped magnet pieces 2, 3, 4, and 5 formed by dividing a cylindrical shape into four in the axial longitudinal direction around a rectangular column-shaped square shaft 1. The entire magnet is formed by alternately forming S poles and N poles. 2, a soft resin magnet having a Vickers hardness of 20 or less (hereinafter referred to as a soft resin magnet) is used for the lower magnet piece 3 and the left magnet piece 4, and the right magnet piece 2; A semi-rigid resin magnet (hereinafter referred to as a semi-rigid resin magnet) having a Vickers hardness of 20 to 100 is used for the upper magnet piece 5. In the present specification, a hard resin magnet having a Vickers hardness of 100 or more is referred to as a hard resin magnet to be distinguished. The unit of Vickers hardness is kgf / mm ² , but the unit is omitted in the specification.
[0010]
The Vickers hardness of the semi-rigid resin magnet pieces 2 and 5 is set to 20 to 100 when the Vickers hardness is 20 or less, it becomes a normal soft resin magnet, and when the Vickers hardness is greater than 100, Post-processability such as outer peripheral cutting for aligning the diameter and cutting for determining the length in the longitudinal direction of the shaft is deteriorated, and the magnet piece itself is warped or bent, so that the adhesion to the square shaft 1 is poor. Because it becomes. Considering the post-processability, adhesiveness, and meandering of the magnets, it is preferable to use a semi-rigid resin magnet having a Vickers hardness of 30 to 60.
Moreover, in order to make a semi-rigid resin magnet, it can be easily performed by reducing the resin content of the soft resin magnet or by appropriately changing the kind and additive of the resin. For example, examples of the resin include vinyl chloride, polyamide, urethane, epoxy, phenol, and polyester, and examples of the additive include fatty acid metal salts, higher fatty acids, fatty acid esters, and waxes.
[0011]
In the above-described magnet roll A, the two magnet pieces 2 and 5 are composed of semi-rigid resin magnets. However, if at least one semi-rigid resin magnet piece is applied to an important electrode such as a developing electrode, etc. The soft resin magnet pieces 3 and 4 adjacent to the semi-rigid resin magnet pieces 2 and 5 are bonded along the semi-hard resin magnet pieces 2 and 5, and thus meandering is prevented. It is also possible to configure all the magnet pieces 2, 3, 4, and 5 with semi-rigid resin magnets.
[0012]
As described above, according to the magnet roll A of the present embodiment, the two magnet pieces 2 and 5 are made of semi-rigid resin magnets. Therefore, when the magnets are assembled, the semi-rigid resin magnet pieces 2 and 5 themselves are Since the soft resin magnet pieces 3 and 4 bonded along the magnet pieces 2 and 5 do not meander and can be prevented from meandering, the variation of the magnetic pole position in the longitudinal direction of the shaft is 2 ° or less. A good image can be obtained. The shaft 1 of the present embodiment uses a square shaft, but the cross-sectional shape of the shaft may be round or polygonal, and the cross-sectional shape is not limited.
[0013]
【The invention's effect】
As is clear from the above description, the following operations and effects are achieved.
According to the magnet roll of claim 1, a semi-rigid resin magnet piece having a Vickers hardness of 20 or more and 100 or less is arranged around the square shaft, and the soft resin magnet piece having a Vickers hardness of less than 20 along the magnet piece. which is configured adjacent arranged, when assembled magnet, the semi-rigid resin magnet piece itself is not meander, further soft resin magnet pieces are bonded along the magnet pieces can be prevented from meandering Therefore, the variation of the magnetic pole position in the longitudinal direction of the shaft is 2 ° or less, and a good image can be obtained.
[0014]
Further, at least one semi-rigid resin magnet piece according to the present invention may be disposed on an important pole around a square shaft as described in claim 2, and the Vickers hardness is 30 to 60 as described in claim 3. By doing so, it is possible to prevent the meandering of the magnet while maintaining good post-processability and adhesiveness.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a magnet roll according to a typical embodiment of the present invention. FIG. 2 is an enlarged side view of the magnet roll. FIG. 3 is a perspective view showing a conventional magnet roll.
A Magnet roll 1 Square shaft 2 Semi-rigid resin magnet piece 3 Soft resin magnet piece 4 Soft resin magnet piece 5 Semi-hard resin magnet piece

Claims (3)

A magnet roll in which a plurality of bar-shaped magnet pieces are fixedly arranged around a square shaft, and a magnet piece made of a semi-rigid resin magnet having a Vickers hardness of 20 to 100 is arranged around the square shaft, A magnet roll of a developing device or a cleaning device for an image forming apparatus, wherein a magnet piece made of a soft resin magnet having a Vickers hardness of less than 20 is disposed adjacent to the magnet piece.   The magnet roll according to claim 1, wherein at least one magnet piece made of the semi-rigid resin magnet is arranged on an important pole around a square shaft.   The magnet roll according to claim 1 or 2, wherein the semi-rigid resin magnet has a Vickers hardness of 30 to 60.

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