JPH01140615A - Manufacture of magnet roll - Google Patents

Abstract

PURPOSE:To obtain a magnet roll having high magnetic force and high productivity by molding a pole piece, a sectional shape of which takes a fan shape and in which an axis of easy magnetization composed of ferrite powder is orientated and magnetized to other three sides from a circular central section, and insert- molding a shaft section. CONSTITUTION:A composite resin magnet pellet is molded by using a mold 5 constituted of a magnetic material 3 forming a magnetic path to other three sides from a circular central section and a non-magnetic material 4 by an injection molding machine 1. An axis of easy magnetization composed of ferrite particles is orientated in the direction of the line of magnetic force by a magnetic field generated by conducting a coil 2, and a pole piece 6, a sectional shape of which takes a fan shape and which is oriented to other three sides from the circular central section, is acquired. Metallic shaft end sections 7 are insert-molded at both ends of the bottom of one pole piece 6 at that time, and other pole pieces 6 are laminated around the pole piece 6, thus obtaining a columnar magnet roll. Accordingly, the magnet roll having high magnetic force can be manufactured easily at low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a magnet roll for magnetic brush development used in electrophotographic copying machines and facsimile receivers.

2. Description of the Related Art As shown in FIG. 6, a conventional magnet roll for magnetic brush development is made by integrally molding ferrite particles into a cylindrical shape around a shaft 11, going through a sintering process, and then polishing the outer periphery and magnetizing it. A sintered ferrite magnet 12 was obtained and was rotatably incorporated into a cylindrical sleeve 13. Further, as shown in FIG. 7, a sintered ferrite magnet 14 obtained by polishing and magnetizing a sintered anisotropic magnet into a square column is pasted radially around the outer circumference of the shaft 16 to form a cylindrical shape. It was constructed such that it was rotatably incorporated within the sleeve 16 of the.

Problems to be Solved by the Invention In such a conventional configuration, since both magnet rolls for magnetic brush development require a sintering process, the shrinkage rate of the sintered ferrite magnet 12°14 is partially reduced under sintering conditions. There was a problem in that it was difficult to obtain uniform dimensions for different sizes. Further, polishing is required as a post-process, but the sintered ferrite magnets 12 and 14 are brittle and easily damaged, which is a significant disadvantage in terms of yield. Furthermore, the magnet roll for magnetic brush development shown in Fig. 6 is very heavy because it is an integral type with a specific gravity of 6.0 to 6.2. There is a limit to the shape of the outer diameter, and it is impossible to obtain a compact one.

In order to improve these drawbacks, resin magnet rolls based on resin or rubber have recently come into use.

As shown in FIGS. 8 and 9, the method for manufacturing the resin magnet roll is to mechanically orient the axis of easy magnetization of the ferrite particles in the resin magnet material in one direction to make them anisotropic. The ferrite powder 17 is kneaded with a pressure kneader or the like, then crushed, and while being sheeted with a rolling roller 19 or the like, the axis of easy magnetization of the ferrite particles 17 is oriented in a certain direction to obtain a sorted magnet material 20. The most common method for winding this around the shaft 21 is to cut it to a predetermined length and then magnetize it according to a desired polar pattern to obtain a magnet roll.

Furthermore, as shown in FIGS. 10a-e and 11, after overlapping several rolled sheets 20, two molds 22, 23 are formed.
The molded body 24 is press-molded into a fan shape using
There is a method of pasting 6.

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

The latter has a sufficient magnetic flux density because the axis of easy magnetization is oriented toward the pole, but has the problem of complicating the manufacturing process such as sheet orientation, press working, and pasting of pieces, resulting in poor productivity.

The present invention solves these problems and provides a method for manufacturing a magnet roll with high magnetic force and high productivity by obtaining oriented magnetic pole pieces with a fan-shaped cross section using a composite resin magnet roll. It is.

Means for Solving the Problem In order to solve this problem, the method for manufacturing a magnet roll of the present invention uses a magnetic material in which a composite resin magnet material made of ferrite powder and a polymeric material is placed in a coil for magnetic field orientation. Using an orientation mold made of a combination of non-magnetic materials, a magnetic pole piece with a fan-shaped cross-section and magnetized by orienting the axis of easy magnetization of the ferrite powder from the center of the arc to the other three sides is molded. , a method in which a plurality of magnetic pole pieces whose shaft portions are insert-molded are bonded together as a reference.

Effect By using the above method, after insert molding the ends of the metal shaft at both ends of the bottom of one magnetic pole piece, by combining multiple other magnetic pole pieces, it is possible to easily produce a high magnetic force magnet roll at low cost. become.

EXAMPLE Hereinafter, a method for manufacturing a magnet roll in an example of the present invention will be explained with reference to the drawings.

Kneading ferrite powder and polymer material in a pressure kneader and cooling 1. After that, the pellets are crushed to an appropriate particle size to obtain composite resin magnet pellets.

This berent material is molded into a fan-shaped recess 3ai in the center of the coil 2 as shown in FIG.
The provided lower magnetic material 3b and the T-shaped upper magnetic material 3C form a magnetic path from the center of the arc to the other three sides. It is molded using a mold 6 made of a non-magnetic material 4 surrounding the. coil 2
By energizing and orienting the easy magnetization axis of the ferrite particles in the direction of the lines of magnetic force using the generated magnetic field, a magnetic pole piece 6 having a sector-shaped cross section and oriented from the center of the arc to the other three sides is obtained.

At this time, as shown in FIG. 2, a metal shaft end 7 is insert-molded at both bottom ends of the magnetic pole piece e, and a plurality of other magnetic pole pieces 6 are formed around the shaft side of this magnetic pole piece 6. By pasting them together, a cylindrical magnet roll 8 as shown in FIG. 3 is obtained.

In addition to a pressure kneader, a twin-screw kneading extruder and the like are also effective as kneading equipment, and a general-purpose horizontal injection molding machine can also be used as molding equipment.

The magnetic pole piece 6 has a fan-shaped cross section and is oriented from the center of the arc to the other three sides.

thickness), orientation mold (arc side magnetic material and non-magnetic material dimension ratio),
The magnetic properties (magnetic force, pattern) can be arbitrarily designed depending on the orientation conditions (orientation coil characteristics, orientation current, orientation time), molding conditions (injection pressure, injection temperature), etc. Some of the characteristics of these embodiments are shown in FIGS. 4 and 6.

The magnetic properties of the cylindrical magnet roll 8 obtained by combining a plurality of these magnetic pole pieces 6 depend on the characteristics of the electrophotographic copying machine or facsimile IJ receiver used as the magnet roll for magnetic brush development, and the characteristics of the developer used. Although the requirements differ for each, the mainstream is 4 to 8 poles, and the mainstream is an asymmetric type in which the magnetic force and opening angle of each magnetic pole in a book magnet roll are individually different. . It is a feature of the present invention that these required characteristics can be easily achieved1.In terms of magnetic properties, the orientation is perfect from the circular arc side to the other three sides, and as a combination of multiple magnet rolls, it can be used as a magnetic pole. Once the magnetic path is completed, the magnetic properties will be even better than that of a single piece.

In addition, the shaft, which is essential to constructing a magnet roll, is usually required to be incorporated over the entire length of the magnet roll due to concentricity with the magnet part, bonding strength, etc., which is a factor in increasing costs. However,
According to the present invention, it is sufficient to use only the minimum shaft end portion necessary for the shaft function, and the reference magnetic pole is
Since they are integrated in the mold by insert molding, there are no problems in terms of dimensional accuracy (9) and strength, making it possible to significantly reduce costs.

The ferrite of the resin magnet material used in the present invention is generally given by MOnFe205, where M contains at least one of barium, strontium, and lead.
0 to 90 wt% is desirable. The polymer material is preferably a thermoplastic resin such as polyamide, polyethylene, polypropylene, chlorinated polyethylene, etc., and is preferably blended in an amount of 10 to 2 OWt.

Moreover, there is no problem in adding various additives as necessary.

Effects of the Invention As described above, the magnet roll obtained by the present invention has a magnetic pole piece with a fan-shaped cross-section that can effectively utilize the total magnetic energy from the magnetic pole, and magnetic powder is oriented from the center of the arc to the other three sides. It is easy to produce, the manufacturing process can be greatly shortened, and a structure that requires only the minimum amount of shaft parts is possible, reducing costs.Since the molding is performed in an oriented mold, dimensional accuracy is high and post-processing is easy. It is of great industrial value because it does not require the use of magnet rolls and can be easily manufactured with any design as a magnet roll.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of equipment showing the manufacturing process of magnetic pole pieces constituting a magnet roll in one embodiment of the present invention;
The figure is a perspective view of a magnetic pole piece with metal shaft terminals insert-molded at both ends, Figure 3 is a cross-sectional view of the magnetic roll, Figure 4 is a characteristic diagram showing examples of the effects of factors contributing to the characteristics of the magnetic pole piece, Figure 5 is a characteristic diagram showing the difference in orientation ratio between the arc portion and the other three sides of a fan-shaped magnetic pole piece.
Figures 6 and 7 are cross-sectional views of a conventional magnet roll for magnetic brush development, Figure 8 is a process diagram showing the manufacturing process of a conventional 7-tot-shaped magnet, and Figure 9 is a diagram showing the same sheet-shaped magnet. FIGS. 10a to 10e are process diagrams showing the manufacturing process of a conventional fan-shaped magnet, and FIG. 11 is a perspective view of a magnet roll using the same 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, 6... Mold, 6... Magnetic pole piece, 7... ...Shaft, 8...Cylindrical magnet roll〇Name of agent: Patent attorney Toshio Nakao and 1 other person/---Vertical injection↓Molding tape 2-Coil 3-X44'# 4- Ritaka peach material 3α 3 3b Fig. 2 Fig. 3 Fig. Otsuno Fig. 4 Orientation plot [AJ Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. io Fig. 11

Claims (1)

[Claims] A magnetic pole piece with a fan-shaped cross section is created using an alignment mold made of a combination of magnetic and non-magnetic materials, in which a composite resin magnet material made of ferrite powder and polymeric material is placed in a magnetic field alignment coil. When molding, after insert molding the metal shaft ends at both ends of the bottom of one magnetic pole piece,
A method for manufacturing a magnet roll, characterized by combining and bonding a plurality of magnetic pole pieces whose other cross-sectional shapes are fan-shaped.