JP2725328B2 - 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 for manufacturing a magnet roll for magnetic brush development used in an electrophotographic copying machine or a facsimile receiver.

2. Description of the Related Art A conventional magnet roll for magnetic brush development is a ninth type.
As shown in the figure, ferrite particles are integrally molded into a cylindrical shape around the shaft 11, and after a sintering process, 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.
Further, as shown in FIG. 10, a sintered ferrite magnet 14 obtained by polishing and magnetizing a sintered anisotropic magnet into a square pillar is radially affixed to the outer periphery of a shaft 15 to form a cylindrical shape. And was rotatably incorporated in the sleeve 16.

Problems to be Solved by the Invention In such a conventional configuration, since both magnet rolls for magnetic brush development require a sintering step, the shrinkage ratio of the sintered ferrite magnets 12, 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. Further, in the case of the magnet roll for magnetic brush development shown in FIG.
The magnet roll for magnetic brush development shown in Fig. 10 is very heavy due to the integral shape of 5.2, and the shape of the sintered ferrite magnet 14 is limited due to its limited outer diameter, making it impossible to obtain a small size. It is possible.

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

The manufacturing method of the resin magnet roll is a method in which ferrite particles in the resin magnet material are mechanically orientated with the easy axis of magnetization in one direction as shown in FIGS. 11 and 12,
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 magnetization axis of the ferrite particles 17 in a certain direction while sheeting with a rolling roller 19 or the like. This is a method in which a magnet roll is obtained by winding this around a shaft 21 and cutting it to a predetermined length, and then magnetizing according to a desired pole pattern.

Further, as shown in FIGS. 13 a to e and FIG. 14, several rolled sheets 20 are superimposed and then pressed into a continuous chevron using two dies 22 and 23, and the formed body 24 is formed. Are separated from each other to obtain a magnetic pole piece 25, which is attached to a shaft 26, and the outer periphery is cut into a cylindrical shape.

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, 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, and obtains a magnetic pole piece in which a composite resin magnet is oriented in a sectoral cross section by a magnetic field, so that a magnet roll having high magnetic force, high productivity, and excellent quality can be obtained. Is provided.

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. After forming a magnetic pole piece that is magnetized by orienting the axis of easy magnetization of ferrite powder from the center of the arc to the other three sides from the center of the arc to the other three sides using an alignment mold that is combined with the material In this method, an attachment made of a magnetic material is used when demagnetization is performed to re-magnetize a plurality of magnets in a state of being bonded together.

Here, the re-magnetization refers to demagnetizing and pasting the magnetic pole piece once so that a plurality of magnetic pole pieces can be easily bonded to the magnetic material shaft before the magnetic pole piece oriented and magnetized is bonded to the magnetic material shaft. After the alignment, re-magnetization for obtaining predetermined magnetic characteristics is performed.

By using a magnetic material attachment that makes the dimensions of the magnetic material shaft equal by the above method and connected to the end of the magnetic material shaft in the axial direction and then demagnetizing and then re-magnetizing, the magnetic properties in the longitudinal direction can be improved. It is possible to easily produce a high quality magnet roll having excellent linearity.

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. After demagnetization in the magnetic pole piece state, a plurality of magnetic pole pieces 6 are bonded around a shaft 7 made of a magnetic material such as iron as shown in FIGS.

As the kneading equipment, a twin-screw kneading extruder or the like is effective in addition to the pressure kneader, and a general-purpose horizontal injection molding machine can also be used as the molding equipment. In addition to the injection molding machine, it is also possible to obtain a magnetic pole piece by forming a long piece by using an extrusion molding machine provided with a coil and a mold in front of the die, and then cutting it into a predetermined length.

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). Magnetic material and non-magnetic material dimension ratio), 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. 3 and FIG.

A magnetic pole piece having an orientation pole on the arc side is combined with another magnetic pole piece to realize a magnetized pattern as shown in FIG.

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 having a plurality of poles is mainly 4 to 8 poles, and the asymmetric type in which the magnetic force of each pole and the angle between the poles in one magnet roll are individually different is the mainstream. .

In the asymmetric type, not only the angle between the magnetic poles is different, but also the magnetization level is individually different. In other words, the level of the magnetic force varies, and the poles at which the magnetization level must be controlled to be low tend to be unstable.

The present invention stabilizes the longitudinal direction of the magnetic pole for which the magnetization level needs to be controlled low, and the magnetic pole piece oriented to the molded magnet is not fully magnetized, that is, the magnetization control is performed at a lower level. When it is necessary to perform demagnetization and re-magnetization while the adhesive is fixed to the magnetic material shaft, the linearity in the longitudinal direction deteriorates as shown in FIG. This is because, due to the structure of the magnet roll, it is almost impossible to design the structure of the shaft end portion to be the same on the left and right sides. In order to improve this point, the present invention adds an attachment 9 such that the left and right ends of the shaft are identical to each other.
After demagnetization to the state shown in the figure, re-magnetization is performed, and the longitudinal direction after magnetization is excellent in linearity as shown in FIG. The attachment 9 used is basically made of the same material as the shaft 7 and has the same shape at the left and right ends, and is easily detachable.

The ferrite of the resin magnet material used in the present invention is given by the general formula MOnFe ₂ O ₃ , wherein 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, and when demagnetizing after bonding and fixing to a magnetic shaft, the use of an attachment improves the linearity in the longitudinal direction of the magnetic pole, which needs to control the magnetization level to be low. Magnetization pattern becomes easy, and the manufacturing process can be shortened greatly. Also, since it is molded in an orientation mold, dimensional accuracy is high and post-processing is not required. Furthermore, the design as a magnet roll can be arbitrarily and easily manufactured. It has features such as being able to do so 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.
FIGS. A and b are a cross-sectional view and a perspective view of a magnet roll in which a plurality of magnetic pole pieces are bonded and fixed to a shaft, FIGS. 3 and 4 are characteristic diagrams showing examples of effects of factors contributing to the characteristics of the magnetic pole pieces, FIG. 5 is a characteristic diagram showing a magnetization pattern of a magnet roll in which fan-shaped magnetic pole pieces are combined, FIG. 6 is a conceptual diagram showing a state in which an attachment for demagnetization is attached, and FIG. FIG. 8 is a longitudinal magnetic characteristic diagram of the low magnetic pole when attached and demagnetized and then re-magnetized. FIG. 8 is a longitudinal magnetic characteristic diagram of the low magnetic pole when demagnetized and re-magnetized without using an attachment. 9 and 10 are cross-sectional views of a conventional magnet roll for magnetic brush development, FIG. 11 is a process diagram showing a conventional manufacturing process of a sheet-like magnet,
FIG. 12 is a process diagram showing a manufacturing process of a magnet roll using the sheet magnet, FIGS. 13a to 13e are process diagrams showing a conventional process of manufacturing a fan-shaped magnet, and FIG. It is a perspective view of the magnet roll which was put. 1 Vertical mold injection molding machine 2 Coil 3 Magnetic material 3a Fan-shaped concave portion 3b Lower magnetic material 3c Upper magnetic material 4 Non-magnetic material 5 ... Mold, 6 ... Pole piece, 7 ... Shaft, 8 ... Cylindrical magnet roll,
9 ... Attachment.

Claims (1)

(57) [Claims] 1. A cross-sectional shape of a composite resin magnet material composed of a ferrite powder and a polymer material is formed into a sector shape by using an orientation mold made of a combination of a magnetic material and a non-magnetic material provided in a magnetic field orientation coil. After the magnetic pole pieces are formed and bonded together on a magnetic material shaft, the magnetic pole pieces are demagnetized before re-magnetizing the magnet roll that has been magnetized to obtain the predetermined magnetic characteristics. A method for manufacturing a magnet roll, wherein a magnetic material attachment is connected to one or both ends of the magnetic material shaft in an axial direction so as to make the dimensions of the magnetic material shaft protruding from the portion equal.