JP2864608B2 - Manufacturing method of magnet roll - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magnet roll for developing a magnetic brush used in an electrophotographic copying machine or a facsimile receiver.

2. Description of the Related Art Conventional magnetic brushes for magnetic brush development
As shown in the figure, ferrite particles are integrally formed in a columnar shape around the shaft 11, and after passing through a sintering step, the outer periphery is polished and magnetized to obtain a sintered ferrite magnet 12, which is placed in a cylindrical sleeve 13. It was constructed so as to be rotatable. Also, as shown in FIG. 8, a sintered ferrite magnet 14 obtained by polishing and magnetizing a magnet made into a sintered anisotropic magnet into a rectangular column is radially attached to the outer periphery of a shaft 15,
It was configured to be rotatably incorporated in a cylindrical sleeve 16.

Problems to be Solved by the Invention In such a conventional configuration, since both magnet brushes for magnetic brush development require a sintering step, the shrinkage ratio of the sintered ferrite magnets 12 and 14 is partially reduced under the sintering conditions. However, there is a problem that it is difficult to obtain a certain size. Although polishing is required as a post-process, the sintered ferrite magnets 12 and 14 are fragile and easily broken, which is extremely disadvantageous in terms of yield. Furthermore, in the case of the magnet roll for magnetic brush development shown in FIG.
The magnet roll for magnetic brush development shown in Fig. 8 is very heavy because it is an integral type of 5.2, and the shape of the sintered ferrite magnet 14 is limited, and the outer diameter is limited. Is impossible.

In order to improve these disadvantages, resin magnet rolls based on resin or rubber have recently been used.

As shown in FIGS. 9 and 10, the method of manufacturing the resin magnet roll is to anisotropically orient ferrite particles in the resin magnet material by mechanically orienting the axis of easy magnetization in one direction.
The polymer material 18 and the ferrite powder 17 are kneaded with a pressure kneader or the like, and then pulverized, and the sheet-like magnet material 20 is obtained by orienting the easy axis of the ferrite particles 17 in a certain direction while sheeting with a rolling roller 19 or the like. The most common method is to wind this around the shaft 21, cut it into a predetermined length, and then magnetize it according to the desired pole pattern to obtain a magnet roll.

Further, as shown in FIGS. 11a to 11e and FIG.
After stacking several pieces of 20, it is press-formed into a fan shape using two molds 22 and 23, and the formed body 24 is separated from each other to obtain a magnetic pole piece 25, which is bonded to a shaft 26. There is a way.

In the former, a sufficient magnetic flux density cannot be obtained because the axis of easy magnetization is radially oriented in the radial direction.

In the latter case, sufficient magnetic flux density can be obtained because the easy axis of magnetization is oriented to the pole.
There was a problem that the manufacturing process such as piece bonding was complicated and productivity was poor.

The present invention solves such a problem, using a molding die provided with a pool in the longitudinal direction, and obtaining a magnetic pole piece oriented in a sector shape in cross section by a magnetic field using a composite resin magnet. An object of the present invention is to provide a method for manufacturing a magnet roll having uniform directional characteristics and high magnetic force and high productivity.

Means for Solving the Problems In order to solve this problem, a method of manufacturing a magnet roll according to the present invention comprises a magnetic material and a non-magnetic material in which a composite resin magnet material composed of a ferrite powder and a polymer material is installed in a magnetic field orientation coil. Magnetization of ferrite powder from the center of the circular arc to the other three sides with a fan-shaped cross section using an alignment mold that has a pool of composite resin magnet material at one end in the longitudinal direction. This is a method in which a magnetic pole piece having an easy axis oriented is formed, and a plurality of pieces are bonded to a shaft.

Function By forming and combining the structure of the orientation mold by the above method as a gate system having a pool at the end in the longitudinal direction of the magnetic pole piece, the coaxial ripple characteristics and the entire coaxial characteristics in the entire longitudinal direction including the end are improved. It is possible to easily produce a magnet roll having excellent high magnetic force.

Example Hereinafter, a method of manufacturing a magnet roll according to an example of the present invention will be described with reference to the drawings.

The ferrite powder and the polymer material are kneaded and cooled by a pressure kneader, and then pulverized to an appropriate particle size to obtain a composite resin magnet pellet.

As shown in FIG. 1, a lower magnetic material 3b provided with a fan-shaped concave portion 3a at a central portion provided in a coil 2 and a T-shaped upper magnetic material 3c Using a mold 5 composed of a magnetic material 3 forming a magnetic path from the center of the arc to the other three sides and a non-magnetic material 4 surrounding the upper part of both sides of the fan and the center part of the arc surface. Molding. A magnetic pole piece 6 having a fan-shaped cross section and oriented from the center of the arc to the other three sides is obtained by orienting the axis of easy magnetization of the ferrite particles in the direction of the line of magnetic force by a magnetic field generated by energizing the coil 2.

As shown in FIG. 2, the magnetic pole piece 6 is formed by a mold having a gate structure provided with a pool 9 in the longitudinal direction. After cutting the reservoir 9, as shown in FIG. 3, a plurality of magnetic pole pieces 6 are formed around a shaft 7 made of a magnetic material such as iron.
To obtain a cylindrical magnet roll 8.

As the kneading equipment, a twin-screw kneading extruder or the like is effective other than the pressure kneader, and a general-purpose horizontal injection molding machine can also be used as the molding equipment.

The magnetic pole piece 6 having a fan-shaped cross section and oriented from the center of the arc to the other three sides is composed of a material (ferrite characteristics, base resin, and ferrite content), a piece shape (fan angle, thickness), and an orientation mold (arc side). Dimension ratio of magnetic material to non-magnetic material), orientation conditions (orientation coil characteristics, orientation current, orientation time), molding conditions (injection pressure,
The magnetic characteristics (magnetic force, pattern) can be arbitrarily designed depending on the injection temperature). Some of the characteristics of these embodiments are shown in FIG. 4, FIG. 5, and FIG.

In particular, as shown in FIG. 6 a, a reservoir 9 is provided at the end of the magnetic pole piece 6, and a composite resin magnet material is poured from the reservoir 9 in the longitudinal direction of the magnetic pole piece 6 and molded.
The influence of the orientation magnetic field on the resin flow during molding is small, and the reservoir 9 and the opposite end of the reservoir 9 are also cut by a predetermined amount, so that the longitudinal direction is uniform over the entire region including the end. Characteristics are obtained, and both coaxial ripple and overall coaxial realize very excellent linearity characteristics.

When this embodiment is not used, a small disturbance (ripple) in the linearity as shown in FIG. 6B and a non-linearity particularly in the vicinity of the end portion cause poor overall coaxial characteristics.

The magnetic properties of the cylindrical magnet roll 8 obtained by combining a plurality of these magnetic pole pieces 6 depend on the properties of an electrophotographic copying machine or a facsimile receiver used as a magnet roll for magnetic brush development and the properties of a developer used. However, the number of poles with multiple poles is mainly 4 to 8 poles, and the non-target type in which the magnetic force of each magnetic pole and the angle between magnetic poles in a single magnet roll are individually different is the mainstream. is there. It is also a feature of the present invention that these required characteristics can be easily realized, and in terms of magnetic characteristics, the orientation is completely made from the arc side to the other three sides, a plurality of them are combined, and When a magnetic material such as iron is used for the shaft, the magnetic path can be effectively utilized, and the magnetic properties can be further improved by about 10% by a single magnetic pole piece.

The ferrite of the resin magnet material used in the present invention is given by the general formula MOnFe ₂ O ₃ , where M is at least one of barium, strontium and lead, and is 80 to 90 wt.
% Is desirable. The polymer material is preferably a thermoplastic resin such as polyamide, polyethylene, polypropylene, or chlorinated polyethylene, and is preferably blended in an amount of 10 to 20% by weight. There is no problem even if various additives are added as required.

Effects of the Invention As described above, the magnet roll obtained by the present invention is a magnetic pole piece in which the cross-sectional shape capable of effectively utilizing the total magnetic force energy from the magnetic pole is a sector shape and the magnetic powder is oriented from the center of the arc to the other three sides. It can be easily produced, greatly shortens the manufacturing process, and has excellent coaxial ripple and overall coaxial characteristics by using a method in which a pool is provided at the end of the piece to stabilize the resin flow to the magnetic pole piece. The uniformity of the image quality in the horizontal direction and, consequently, the entire surface of an image of a copying machine or the like in which the developer layer on the sleeve surface is small, such as one-component development, is improved. It is advantageous in that it does not require post-processing, and that it can be easily and easily designed as a magnet roll, and has great industrial value.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a manufacturing process of a magnetic pole piece constituting a magnet roll according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view showing the shape of a magnetic pole piece having a pool after forming the magnetic pole piece, FIG. 3 is a cross-sectional view of the magnetic roll,
FIG. 4 is a characteristic diagram showing an example of the effect of a factor contributing to the characteristics of the magnetic pole piece, FIG. 5 is a characteristic diagram showing the difference in the orientation ratio between the arc portion and the other three sides of the fan-shaped magnetic pole piece, and FIG.
FIGS. 7A and 7B are characteristic diagrams showing the linearity in the longitudinal direction.
FIG. 9 is a cross-sectional view of a conventional magnet roll for magnetic brush development, FIG. 9 is a process diagram showing a conventional manufacturing process of a sheet magnet, and FIG. 10 is a manufacturing process of a magnet roll using the same sheet magnet. The process diagram shown in FIG.
"e" is a process diagram showing a conventional manufacturing process of the fan-shaped magnet, and FIG. 12 is a perspective view of a magnet roll using the fan-shaped magnet. 1. Vertical injection molding machine, 2. Coil, 3. Magnetic material, 3a Fan-shaped recess, 3b Lower magnetic material, 3c Upper magnetic material, 4. Non-magnetic material, 5. ... Mold, 6 ... Pole piece, 7 ... Shaft, 8 ... Cylindrical magnet roll,
9 ... Reservoir.

Claims (2)

(57) [Claims] 1. A fan-shaped cross section using an orientation mold made of a combination of a magnetic material and a non-magnetic material in which a composite resin magnet material made of ferrite powder and a polymer material is placed in a magnetic field orientation coil. When forming the magnetic pole piece, a pool portion of the composite resin magnet material is provided on one end side of the orientation mold, and after the composite resin magnet material is poured from the pool portion in the longitudinal direction of the magnetic pole piece and molded, the pool portion is cut. A method of manufacturing a magnet roll, comprising combining a plurality of these magnetic pole pieces on a shaft and bonding them together. 2. The method for manufacturing a magnet roll according to claim 1, wherein after forming, the tip end farthest from the pool side is cut by a predetermined amount, and then a plurality of the rolls are combined and attached to a shaft.