JPH0215283Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a magnet roll, and particularly to a magnet roll using a block-shaped magnet made of magnetic powder such as ferrite powder bonded with resin or plastic material.

As a means for conveying developer in magnetic brush development, magnetic brush cleaning, etc., a permanent magnet roll having a plurality of magnetic poles on the surface is configured to be relatively rotated inside a cylindrical sleeve made of a non-magnetic material. Magnetroll is used.

As the above-mentioned magnet roll, those having various structures are known.

First, after molding hard ferrite powder in a magnetic field,
A permanent magnet member in which an anisotropic block magnet obtained by connecting the magnets is fixed around the shaft, such as Utility Model Publication No. 57-9798
Although the method described in the above publication is known, it requires a large number of assembly steps and has problems such as low-temperature demagnetization.

In addition, permanent magnet members in which a cylindrical permanent magnet made of hard ferrite is fixed to the shaft, such as the
The one described in Publication No.-6907 is also known.

In addition to these magnet rolls using ferrite magnets, there are also known magnet rolls that use bonded magnets as permanent magnet members to reduce weight. As a magnet roll using this bonded magnet,
As described in JP-A-57-130407 and JP-A-57-164771, ferrite powder and a high molecular weight polymer, such as resin or plastic, are integrally formed into a cylindrical shape by injection molding or extrusion molding. It has also been proposed to use formed permanent magnets,
Multi-pole magnetization on the surface of the cylindrical magnet (usually 3 or more poles, 4 poles or more)
12 poles), there are problems such as insufficient magnetic properties (residual magnetic flux density becomes low).

Therefore, if you want to obtain a magnet roll that is lightweight and has high magnetic force, for example, US Patent Specification 3455276
As described in the above publication, it is common practice to fix a block-shaped bonded magnet magnetized in one direction around a shaft. However, this block-shaped magnet does not have accurate positioning means. Also, since all the block magnets have the same shape, complicated magnetic pole arrangements cannot be made.

Block magnets are therefore advantageous in assembling a magnet roll with a large number of magnets having different dimensions and magnetization directions, but have the disadvantage that precise positioning relative to the axis is not possible.

This invention eliminates these drawbacks,
The object of the present invention is to provide a magnet roll that can be accurately and easily assembled and fixed around a block-shaped magnet.

In order to achieve the above object, the present invention has a polygonal shaft having a plurality of pieces on the outer circumferential surface, which are made of a material in which magnetic powder is bonded with an organic polymer, and have a cross-sectional shape in which at least a part of the outer circumferential surface forms an arc. In a cylindrical magnet roll having fixed block magnets, at least one of the block magnets has a first positioning step that fits into a corner of the shaft;
This first positioning step portion holds the one block-shaped magnet in a predetermined position with respect to the shaft in both the radial and circumferential directions, and also holds the one block-shaped magnet and the adjacent block-shaped magnet at a predetermined position with respect to the shaft. has a second interdigitating locating step on each contact surface, and contact with the second locating step and the shaft causes the adjacent block magnets to be aligned relative to the shaft. and has a configuration in which they are mutually held in predetermined positions.

Embodiments of the present invention will be described below based on the drawings.

Here, FIG. 1 is a plan view of a magnet roll according to one embodiment, and FIG. 2 is a side view thereof.

In the figure, 1 is a magnet roll, 2 is a polygonal shaft with a polygonal cross section, and 2a is a circular shaft with a circular cross section formed at the tip of the polygonal shaft 2.
3, 3a, 3b, 3c, and 3d are block-shaped magnets each magnetized in the direction indicated by the arrow in the figure.
Each block magnet has a different shape and magnetization direction.

FIG. 3 is an exploded view of the magnet roll shown in FIG. 2. The block-shaped magnet 3a has a corner 4 which can fit into a corner 5 of the polygonal shaft 2. Therefore, the block-shaped magnet 3a can be first fixed to the polygonal shaft 2 by fitting the corner 4 with the corner 5. Similarly, the block-shaped magnet 3b has a corner 6 and is then fixed to the polygonal shaft 2. Block magnet 3b
By fitting the corner 6 to another corner of the polygonal shaft 2 and the groove 8 of the magnet 3b to the convex portion 7 of the magnet 3a, it is easy to accurately align the polygonal shaft 2 and the block-shaped magnet 3a. Fixed in position. The block magnets 3c and 3d are then fixed to the polygonal shaft 2 and the block magnets 3b and 3a adjacent to them.
Finally, the block magnet 3e is inserted into the vacant position. In this way, a six-pole magnet roll having a cylindrical overall shape is obtained.

As explained above, in the magnet roll according to this embodiment, the magnet roll 1 is divided into block-shaped magnets 3a, 3b, 3c, 3d, and 3e. Since the convex portions or concave portions that fit into each other are provided, the block-shaped magnets 3a...3e are arranged adjacently to each other on the polygonal shaft 2.
If it is fixed, it can be assembled and fixed accurately and easily, and a regular cylindrical magnet roll is formed.

In the present invention, when the magnet is molded, for example, by injection molding, if the convex part or the concave part is placed in the divided part of the molding die, it is effective to easily take out the magnet after molding.

Further, since block magnets are used in combination, high magnetic properties can be obtained even when a bonded magnet is used as the block magnet, for example.

In the above embodiment, the entire magnet is cylindrical and its center is substantially aligned with the center of the shaft, but it goes without saying that some of the magnets may have irregular cross-sections. .

Specific example: Barium ferrite powder (particle size approximately 1 μm) and resin (nylon 66) are heated and mixed at a weight ratio of 8:2, and then injection molded and magnetized to create each of the block-shaped magnets shown in Figure 3 of the above embodiment. was manufactured. Each of these block-shaped magnets is successively pasted around the shaft,
A magnet roll (Fig. 1) with an outer diameter of 15 mmφ was obtained. In this case, the assembly time was reduced to about 70% compared to the conventional case where there are no protrusions or depressions that can be fitted into adjacent block magnets.

As described above, in the present invention, when a magnet roll is divided into a plurality of block-shaped magnets and the block-shaped magnets are fixed to the outer peripheral surface of a shaft having a polygonal cross section, at least one block-shaped magnet Since the positioning steps that can fit into the corners of the polygonal shaft are provided, this magnet can be accurately positioned with respect to the shaft, and the contact surfaces of this magnet and the adjacent magnets are also mutually connected. Since the positioning steps that can be fitted are provided, adjacent magnets can be accurately positioned with respect to the shaft and the one magnet, and the magnet roll can be assembled in a shorter time than before. This can be said to be a device with excellent practical effects.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a magnet roll according to an embodiment of the present invention, FIG. 2 is a side view thereof, and FIG. 3 is an exploded view of FIG. 2. 1... Magnet roll, 2... Polygonal axis, 3
a, 3b, 3c, 3d, 3e, 3f, 3g, 3
h, 3i... block magnet.

Claims (1)

[Scope of utility model registration request] A cylindrical magnet roll in which a plurality of block-shaped magnets made of a material made of magnetic powder bonded with an organic polymer and having a cross-sectional shape in which at least a portion of the outer circumferential surface forms an arc are fixed to the outer circumferential surface of a polygonal shaft. At least one of the block-shaped magnets is
It has a first positioning step that fits into the edge of the shaft, and this first positioning step allows the first
block-shaped magnets are held in place both radially and circumferentially with respect to the axis, and
The one block magnet and the adjacent block magnet have a second interfittable positioning step on each contact surface, the second positioning step and contact with the shaft. A magnet roll characterized in that said adjacent block-like magnets are held in position relative to said shaft and relative to each other.