JP2512035B2 - Magnet roll manufacturing method - Google Patents

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 The conventional magnet roll for magnetic brush development is
As shown in the figure, the ferrite particles are integrally molded around the shaft 11 in a cylindrical shape, and after the 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 configured to be rotatable.
Further, as shown in FIG. 10, a sintered ferrite magnet 14 obtained by polishing a magnetized sinter-anisotropic magnet into a square pole and magnetized it is radially attached to the outer periphery of the shaft 15 to form a cylindrical shape. It was configured to be rotatably incorporated in the sleeve 16.

Problems to be solved by the invention In such a conventional configuration, since the magnet roll for developing both magnetic brushes requires a sintering process, the shrinkage ratio of the sintered ferrite magnets 12 and 14 is different under the sintering conditions. There is a problem that it is difficult to obtain a certain size, which is partially different. Further, polishing is required as a post-process, but the sintered ferrite magnets 12 and 14 are brittle and thus easily damaged, which is a significant disadvantage in terms of yield. Furthermore, in the case of the magnet roll for magnetic brush development shown in FIG.
Since it is an integrated type of 5.2, it is very heavy, and the magnet roll for magnetic brush development in FIG. 10 has a limitation on the shape of the sintered ferrite magnet 14 and the outer diameter size is limited. It is impossible.

Recently, resin magnet rolls based on resin or rubber have been used for the purpose of improving these drawbacks.

The method of manufacturing a resin magnet roll is a method in which ferrite particles in a resin magnet material are mechanically orientated in one direction with an axis of easy magnetization as shown in FIG. 11 and FIG.
The polymer material 18 and the ferrite powder 17 are kneaded with a pressure kneader or the like, then pulverized, and the easy axis of magnetization of the ferrite particles 17 is oriented in a fixed direction while sheeting with a rolling roller 19 or the like to obtain a sheet-shaped magnet material 20. The most common method is to wind this around a shaft 21 and cut it to a predetermined length, and then magnetize it according to a desired pole pattern to obtain a magnet roll.

Furthermore, as shown in FIGS. 13a to 13e and FIG.
After stacking several 20 pieces, they are press-formed into a fan shape by using two molds 22 and 23, and the formed bodies 24 are separated to obtain magnetic pole pieces 25, which are attached to the shaft 26. There is a way.

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

The latter has sufficient magnetic flux density because the axis of easy magnetization is oriented to the pole, but orientation and pressing with a sheet,
There has been a problem that the manufacturing process such as piece bonding becomes complicated and the productivity is poor.

The present invention solves such a problem, and provides a method for manufacturing a magnet roll having high magnetic force and high productivity by obtaining a magnetic pole piece having a fan-shaped cross-section with a composite resin magnet by a magnetic field. It is a thing.

Means for Solving the Problems In order to solve this problem, a method for manufacturing a magnet roll of the present invention is a magnetic material in which a composite resin magnet material made of ferrite powder and a polymer material is installed in a coil for magnetic field orientation. When forming a magnetized magnetic pole piece by using an orienting die made of a combination with a non-magnetic material and having a fan-shaped cross section and orienting the easy axis of the ferrite powder from the center of the arc to the other three sides. A method of forming by giving two or more orientation poles on the arc side of a single piece, and laminating at least one or more magnetic pole pieces having the orientation poles of two or more, together with other magnetic pole pieces, on a shaft. Is.

Operation By the above-mentioned method, by changing the combination structure of the magnetic material part and non-magnetic material part of the orientation die, and changing the dimensional ratio, two or more orientation poles are formed on the arc side in the single magnetic pole piece. By molding and combining the magnetic pole pieces,
It becomes possible to easily produce a magnet roll with high magnetic force.

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

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

As shown in FIG. 1, in the vertical injection molding machine 1 of this pellet material, a lower magnetic material 3b having a fan-shaped concave portion 3a provided in a central portion installed in a coil 2 and a T-shaped upper magnetic material 3c. Using a mold 5 composed of a magnetic material 3 that forms a magnetic path from the central part of the arc to the other three sides and a non-magnetic material 4 that surrounds the upper parts on both sides of the fan and the central part of the arc surface Mold. A magnetic field generated by energizing the coil 2 causes the easy axis of magnetization of the ferrite particles to be oriented in the direction of the magnetic force lines, thereby obtaining a magnetic pole piece 6 having a fan-shaped cross section and oriented from the arc center to the other three sides. At this time, as shown in FIG. 2, in a specific magnetic pole piece, the magnetic material 3 forming the magnetic path on the arc side is formed by a mold divided into two, and the ferrite particles as shown in FIG. A magnetic pole piece 6 whose easy axis of magnetization is oriented between arcs and on the other three sides is obtained. Then, as shown in FIG. 4, a plurality of magnetic pole pieces 6 are attached 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 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 molding as a long product with an extrusion molding machine equipped with a coil and a die in front of a die and then cutting it into a predetermined length dimension.

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 made of material (ferrite characteristics, base material resin, ferrite content), piece shape (fan angle, thickness), orientation die (arc side). Magnetic material and non-magnetic material size ratio), orientation conditions (orientation coil characteristics, orientation current, orientation time), molding conditions (injection pressure,
The magnetic characteristics (magnetic force, pattern) can be arbitrarily designed by the injection temperature). Some of the characteristics of these examples are shown in FIGS. 5 and 6.

The magnetic pole piece having two or more orientation poles on the arc side of a single piece is combined with other ordinary pieces or used alone to realize the magnetization pattern as shown in FIGS. 7 and 8.

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

The ferrite of the resin magnet material used in the present invention is given by the general formula MOnFe ₂ O ₃ , and M contains 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 in an amount of 10 to 20 wt%. Further, there is no problem even if various additives are added as needed.

Effects of the Invention As described above, the magnet roll obtained by the present invention has a magnetic pole piece in which magnetic powder is oriented from the arc center to the other three sides so that the total magnetic energy from the magnetic pole can be effectively utilized. It can be easily produced, and by forming multiple orientation poles in a single piece and combining them, it is possible to easily create a very arbitrary magnetizing pattern such as a double-sided pole, and the manufacturing process can be greatly shortened. Since the molding is performed in the orientation mold, the dimensional accuracy is high, there is no need for post-processing, and the design as a magnet roll can be arbitrarily and easily manufactured, which is of great industrial value.

[Brief description of drawings]

FIG. 1 is a schematic equipment diagram showing a manufacturing process of a magnetic pole piece constituting a magnet roll according to an embodiment of the present invention.
The figure is a schematic diagram of a mold for forming multiple orientation poles in a single piece, and Fig. 3 is a schematic view of the direction of the easy axis of magnetization of ferrite particles in a pole piece in which two orientation poles are formed. 4 is a cross-sectional view of the same magnet roll in which various pieces are combined, FIG. 5 is a characteristic diagram showing an example of the effect of factors contributing to the characteristics of the magnetic pole piece, and FIG. 6 is a fan-shaped magnetic pole. FIG. 7 is a characteristic diagram showing the difference in orientation ratio between the arc portion of the piece and the other three sides. FIG. 7 is a characteristic showing an embodiment of a magnet roll incorporating a magnetic pole piece in which a two-pole orientation pole is formed in a single piece. FIG. 8 and FIG. 8 are characteristic diagrams showing an embodiment of a magnet roll using a magnetic pole piece having a dipole orientation pole formed in a single piece, FIG. 9, FIG.
FIG. 10 is a cross-sectional view of a conventional magnet roll for magnetic brush development, FIGS. 11 and 12 are process diagrams showing a manufacturing process of a conventional sheet magnet, and FIGS. 13A to 13E are conventional fan-shaped magnets. And FIG. 14 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, 5 ... … Mold, 6 …… Magnetic pole piece, 7 …… Shaft, 8 …… Cylindrical magnet roll.

Claims (1)

(57) [Claims] 1. A cross-sectional shape is fan-shaped using an orienting die made of a combination of a magnetic material and a non-magnetic material, in which a composite resin magnet material composed of ferrite powder and a polymer material is installed in a coil for magnetic field orientation. When forming a magnetic pole piece that consists of two or more orientation poles on the arc side of a single piece, then form at least one pole piece with more than two orientation poles together with other pole pieces. A method of manufacturing a magnet roll, which is characterized by combining multiple shafts and bonding them together.