JPH02194606A - Manufacture of magnet roll - Google Patents

Abstract

PURPOSE:To enhance magnetic force and to improve productivity and quality by using an orientation metal mold comprising the combination of a magnetic material and a non-magnetic material, and forming a magnetic pole piece having a fan-shaped cross section wherein magnetic powder is oriented toward the other three sides from the central part of the arc of the fan. CONSTITUTION:Ferrite powder and macromolecular material is kneaded in a compressing kneader and cooled. Thereafter, the material is crushed, and composite resin magnetic pellet is obtained. The pellet material is treated in a vertical injection molding machine 1. The pellet material is molded by using a metal mold 5 which is composed of the following parts: a lower magnetic material 3b which is provided in a coil 2 and wherein a fan-shaped recess part 3a is provided at the central part; a T-shaped upper magnetic material 3c; a magnetic material 3 which forms magnetic paths to the other three sides from the central part of the arc of the fan shape together with said material 3b and said material 3c; and a non- magnetic material 4 which surrounds the part of the fan shape other than the upper parts of both sides and the central part of the arc surface. A current is conducted through the coil 2, and the axis of easy magnetization of the ferrite particles is oriented in the direction of the magnetic lines of force by a generated magnetic field. A magnetic pole piece 6 which has the fan-shaped cross section and wherein the magnetic powder is oriented from the central part of the arc to /he other three sides is obtained. A magnetic pole yoke wherein a plurality of magnetic pole pieces 6 are stuck around a shaft 7 is used, and a magnet roll 8 is obtained.

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.

Conventional technology As shown in Figure 8, the conventional magnet rope for magnetic brush development consists of integrally molding ferrite particles into a cylindrical shape on a shaft 110 times, going through a sintering process, and then polishing the outer periphery and magnetizing it. A sintered ferrite magnet 12 was obtained, which was rotatably incorporated into a cylindrical sleeve 13. Further, as shown in FIG. 9, 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. However, there was a problem in that it was difficult to obtain constant dimensions. Further, polishing is required as a post-process, but the sintered ferrite Magnef) 12.14 is brittle and easily damaged, which is a significant disadvantage in terms of yield. Furthermore, the magnet roll for magnetic brush development shown in Fig. 8 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 tube, and the outer diameter is limited, making it impossible to obtain a compact one.

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

The method for manufacturing the resin magnet roll is shown in Figure 10.

As shown in FIG. 11, the polymeric material 18 and ferrite powder 17 were kneaded using a pressure kneader or the like by mechanically orienting the axis of easy magnetization of the ferrite particles in the resin magnet material in one direction to make them anisotropic. After crushing, the easy axis of magnetization of the ferrite particles 17 is oriented in a certain direction while being sheeted by a rolling roller 19 or the like to obtain a sheet-like 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, Figure 12 &-15. As shown in FIG.
, 23 into a fan shape, the molded body 24 is separated from each other to obtain a magnetic pole beef 26, and this is bonded to the shaft 26.

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 piece bonding, resulting in poor productivity.

The present invention solves these problems by using a magnetic field to obtain oriented magnetic pole pieces with a fan-shaped cross section from a composite resin magnet, thereby producing a magnet roll with high magnetic force, high productivity, and excellent quality. The present invention provides a method for manufacturing.

Means for Solving the Problem In order to solve this problem, the method for manufacturing a magnet roll of the present invention consists 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 coil for magnetic field orientation. Using an orientation mold consisting of a combination of 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, and after pasting together several shirts, the desired magnetic properties are obtained. Therefore, when magnetizing the magnetic roll, a magnetizing yoke having a certain inclination and having a certain space at both ends in the longitudinal direction of the magnet roll is used.

Effect: By using the method described above, it becomes possible to easily produce a high-magnetic-force magnet roll with controlled magnetic properties in the longitudinal direction and excellent coaxial properties.

EXAMPLE A method of manufacturing a magnet row according to an embodiment of the present invention will be described below with reference to the drawings.

Ferrite powder and polymeric material are kneaded and cooled in a pressure kneader, and then ground to an appropriate particle size to obtain composite resin magnet pellets.

This pellet material is molded into a vertical injection molding machine 1 with a fan-shaped recess 3 in the center of the coil lv2 as shown in FIG.
A lower magnetic material 3b provided with an L and a T-shaped upper magnetic material 3C
and a magnetic material 3 that forms a magnetic path from the center of the arc to the other three sides.
The metal mold 6 is made of a non-magnetic material 4 that surrounds the upper portions of both sides of the fan shape and the arcuate surface except for the center. By energizing the coil 2 and orienting the axis of easy magnetization 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 fan-shaped cross section and oriented from the center of the arc to the other three sides is obtained.

After being demagnetized by - degrees, as shown in FIG.
A cylindrical magnet roll 8 is obtained which is magnetized to have predetermined magnetic properties using a magnetizing yoke.

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

The magnetic pole piece 6, which has a fan-shaped cross section and is oriented from the center of the arc to the other three sides, is made of material (ferrite properties, base material resin, ferrite content), piece shape (fan angle, thickness), orientation mold (
Depending on the size ratio of arc side magnetic material and non-magnetic material), orientation conditions (orientation coil characteristics, orientation current, orientation time), molding conditions (injection pressure, injection temperature), magnetization conditions (yoke structure, magnetization current), etc. Its magnetic properties (magnetic force/pattern) can be designed arbitrarily.

Some of the characteristics of these embodiments are shown in Figures 3, 4, and 5.
As shown in the figure.

In particular, as shown in Figure 6a, according to the normal magnetization method,
Due to the edge effect, the magnetic properties at both ends are raised, but this is due to the fact that the orientation magnetic force on the surface of the piece after injection molding in a magnetic field is concentrated at both ends in the longitudinal direction, as shown in Figure 5. However, in the present invention, an inclined gap 1o is provided at both ends as shown in FIG. 6 during magnetization after orientation demagnetization.
Flat magnetic characteristics as shown in FIG. 7 are realized by using a magnetizing yoke 9 having a magnetizing state that gives a difference in magnetizing efficiency in the longitudinal direction. The dimensional difference of the magnetizing yoke 9 to be corrected varies depending on the magnetic pole arrangement and magnetic force.

The magnetic properties of the cylindrical magnet RO/L/8 obtained by combining a plurality of these magnetic pole pieces 6 depend on the characteristics of the electrophotographic copying machine or facsimile receiver used as a magnet roll for magnetic plan development and the developer used. Although the individual requirements differ depending on the characteristics, the mainstream number of multiple poles is 4 to 8 poles. type is the mainstream. It is a feature of the present invention that these required characteristics can be easily achieved, and the magnetic properties are perfectly oriented from the circular arc side to the other three sides, and the shaft When a magnetic material such as iron is used, the magnetic path can be effectively utilized, and the magnetic properties are further improved by about 10% compared to a single piece.

The ferrite of the resin magnet material used in the present invention is general 2 MOnFe20. M contains at least four types of barium, strontium, and lead, and 8
0 to 6 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 20 wt%.

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 by giving a difference in magnetization efficiency in the longitudinal direction, it is possible to improve the linearity of the magnetic properties on the sleeve surface, making it possible to improve the linearity of magnetic properties on the sleeve surface. It improves the uniformity of image quality in the lateral direction and even over the entire surface, and since it is molded in an orientation mold, it has high dimensional accuracy and does not require post-processing, and can be designed as a magnetic roll and easily manufactured. Fig. 1 is a schematic diagram of equipment showing the manufacturing process of a magnetic pole piece constituting a magnet roll in an embodiment of the present invention, Fig. 2 is a perspective view of the same magnet roll, and Fig. 3 shows factors contributing to the characteristics of the magnetic pole piece. A characteristic diagram showing an example of the effect, Figure 4 shows the magnetism on the sleeve surface when the fan-shaped magnetic pole piece is magnetized with the same efficiency and when both ends of the W in the valve are magnetized with a slightly smaller efficiency than the center. A characteristic diagram showing the difference in characteristics, Fig. 6 is a cross-sectional view showing the relationship during magnetization between the magnetizing yoke and the magnet roll, which give a difference in magnetization efficiency between both ends and the center, and Figs. 8 and 9 are FIG. 10 is a cross-sectional view of a conventional magnet roll for magnetic brush development; FIG.
The figure is a process diagram showing the manufacturing process of a magnet roll using the same sheet-like magnet, Figures 12a to 12 are process diagrams showing the manufacturing process of a conventional fan-shaped magnet, and Figure 13 is a perspective view of the same fan-shaped magnet roll. It is.

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, 9...
...Magnetizing yoke.

Name of agent: Patent attorney Shigetaka Awano and 1 other person 1st
Figure -m- 2-・ 3-・ 5-・・ 6-・ -m- Vertical S! Injection triad coil sulfur steel non-magnetic material tL type aI bead shaft 42 Fig. 3-5 Fig. Longitudinal direction same - first spicy t@magnetic temporary → Ma'5 net roll longitudinal direction orientation Sparrow CA ) Lu Tu Diagram Longitudinal @ Machine tfn Science -〇・Eta I → Fuku 卆 Troll Longitudinal Direction Half 0 Ku Ishuyu Ku Zuzu @ 12 Yumeng 3 Dia

Claims (1)

[Claims] A composite resin magnet material made of ferrite powder and a polymeric material is installed in a magnetic field alignment coil, and an alignment mold made of a combination of magnetic metal material and non-magnetic metal material is used to create a magnet with a fan-shaped cross section from the center of the arc. After molding a magnetic pole piece with ferrite powder oriented to the other three sides and bonding multiple pieces together to the shaft material, when magnetizing to obtain the desired magnetic properties, the magnetic pole pieces are fixed at both ends of the magnet roll. A method for manufacturing a magnet roll that is magnetized using a magnetizing yoke that has an inclined gap of .