JPH0682579B2 - Magnetoroll and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a magnet roll and a method for manufacturing the same, and more particularly to a novel magnet roll that is lightweight and has a reduced material cost, and a method for manufacturing the same. is there. The magnet roll of the present invention is used in a developing device and a cleaning device such as an electronic copying machine and a printer.

“Prior Art and Problems” Conventionally, this type of magnet roll has shown a typical example in FIG. 1. However, a shaft (1) is arranged at the center and a magnet (2) having a circular cross section is used. Although not shown, this is attached to the magnet roll support of a developing machine such as a copying machine, and a sleeve made of a non-magnetic material such as aluminum or SUS304 is arranged on the outer periphery of the developing machine to convey powdery developer or the like. Used. However, in such a circular magnet roll, the portion that does not substantially affect the surface magnetic field peak value occupies the same weight as the portion that exhibits the surface magnetic field peak value, which impedes the demand for weight reduction.

Further, in order to manufacture the circular magnet roll as described above, the extruded C-shaped long magnet is wound around a reel, and is precisely cut together with another C-shaped long magnet in a separate process to surround the shaft. The method of adhering to is practiced. However, in such a method, since the cross section is C-shaped, it is difficult to align the reel when winding the reel, and the C-shaped may be broken or deformed, or in some cases, cracked. As a result, in the finished magnet roll, the change in the surface magnetic field in the longitudinal direction is remarkable, and the variation in the magnetic flux density in the longitudinal direction is poor, and it is difficult to obtain good copying characteristics.

“Means for Solving Problems” In view of the above-mentioned circumstances, the present inventors have considered that the copy characteristic is related to the surface magnetic field peak value of the magnet roll and does not substantially affect the peak value (inter-pole portion). ) Is deleted,
Paying attention to the fact that the copying characteristics are not affected, by removing the portion, the weight of the magnet roll and therefore the copying machine incorporating the magnet roll can be reduced, and at the same time the material cost can be reduced, and the conventional method. The present invention has been completed by finding a manufacturing method free from such defects.

That is, the first aspect of the present invention is a magnet roll characterized by having three or more poles of anisotropy, and the magnetic pole portion of the cross section is more convex than the interpolar portion, and the second aspect of the present invention is magnetic field orientation. By extrusion molding, a resin or rubber magnet material is extruded in two strands so that the magnetic pole portion is more convex than the interelectrode portion and the magnet having a substantially C-shaped cross-section is formed so that the C-shaped openings face each other. A method for manufacturing a magnet roll is characterized in that a shaft is inserted between openings of facing C-shaped magnets, and then the C-shaped magnets are bonded and fixed so as to sandwich the shaft.

Referring to the drawings showing the embodiment of the present invention, in FIG. 2, the portions (interpole portions) (2bI) to (2bIV) that do not substantially affect the surface magnetic field peak value are flat, and the magnetic pole portions are flat. (2aI) to (2aIV) are formed in a convex shape. That is, the portions (2bI) to (2bIV) between the magnetic poles have a shape in which only the difference from the circle shown by the broken line is deleted.

FIG. 3 shows another embodiment of the present invention.
I) to (2bIV) are recessed, and the magnetic pole part (2aI)
~ (2aIV) has a large convex shape. Also in this case, the shape is deleted by the difference as compared with the case of the conventional circle shown by the broken line.

4 and 5 respectively show another embodiment of the present invention, which has a substantially C-shaped cross section cut between the magnetic poles (2aI) (2aIV) and the magnetic poles (2aII) (2aIII). Magnet (2
A) and (2B) are laminated around the shaft (1) with an adhesive. The magnetic poles may be bonded together, but the bonding between the magnetic poles as shown in FIGS. 4 and 5 allows the bonding work to be effectively performed by the suction action between N and S. The joint surfaces of the C-shaped magnets do not have to be in close contact with each other, and may be slightly open.

In the present invention, the shaft (1) is made of plastic, metal, or any other known material, and the cut surface thereof is not limited to a circular shape and may be a square shape or the like. As the adhesive, known adhesives such as epoxy type and cyanoacrylate type are used.

The magnet material of the present invention is preferably a resin or rubber magnet material, such as EVA, polyamide, PP, P
E, PVC, acrylic resin, methacrylic resin, chlorinated polyethylene resin, PET, PBT, PPS, polycarbonate, silicone rubber, NBR, SBR and the like are used alone or in combination, and also magnetic powder used in the present invention As the magnetic powder, an intermetallic compound magnetic powder containing a magnetoplumbite type Sr or Ba ferrite and a rare earth metal is preferable. Known additives are used depending on the purpose. That is, for the dispersibility of the magnetic powder, an appropriate surface treatment agent is used according to the resin used, and for example, a silane coupling agent, a titanate coupling agent, a silcoaluminate coupling agent, a higher fatty acid and its metal. This includes salts, phosphonates and the like. Additives such as stability improvers, antioxidants, ultraviolet absorbers, lubricants, etc. are also appropriately used depending on the purpose and in relation to the resin.

The magnet roll of the present invention is preferably manufactured by the following method. In FIG. 6 and FIG. 7, the magnets (2A) and (2B) having a substantially C-shaped cross-section and having a magnetic pole portion that is more convex than the inter-electrode portion from the extruder (4) are opposed to each other. C-shaped cross-section magnet (3A) (3A) (3
Insert the shaft (1) coated with an adhesive (not shown) between the openings of B), and bond and fix the shaft (1) by sandwiching it with the C-shaped cross-section magnets (3A) (3B). Then, a magnet roll as shown in FIG. 5 is obtained. In the figure, (5) and (6) are guide rolls.

"Examples" Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Examples 1-2, Comparative Example 1 After mixing the compounds listed in Table 1 with a high speed rotary blade stirrer,
Kneading with a kneader kneader (Bus Co.), diameter 3 mm x length 3
mm pellets were made.

Table 1 Ferrite (GP330, manufactured by Toda Kogyo) 90 wt% Vinyl chloride resin (S1001, manufactured by Kanebuchi Kagaku Kogyo) 7〃 DOP 2.8〃 Tribase 0.1〃 Lead stearate 0.1〃 Using the above pellets, shown in Fig. 6 According to the process
A C-shaped cross-section magnet was extruded in two strands using an extrusion molding machine with an electromagnet for polar orientation, precision cut, and after the shaft and the magnet were bonded, a magnet roll as shown in FIGS. 4 and 5 was obtained. The positional relationship with the magnetic poles of the electromagnet of the molding machine was as shown in FIG. In Fig. 8, (7a) (7b)
Is a void, (8) is a soft magnetic yoke, and (9) is an electromagnet coil.

At the same time, for comparison, a magnet roll having a bonding surface between magnetic poles in FIG. 1 is formed by a conventional method in which a C-shaped cross-section magnet is individually wound on an extrusion reel, then precision cut, and a shaft and a magnet are adhered by a conventional method. Got

About the obtained magnet roll, weight, material cost,
The variations in magnetic flux density in the longitudinal direction and the copying characteristics (density) were observed, and at the same time, the differences in the processes are shown in Table 2.

[Operation / Effect] As described above, the magnet roll of the present invention is made lightweight and the material cost is reduced, and according to the method of the present invention, the obtained magnet roll has no dent, crack, twist, or the like. As a result, the variation in magnetic flux density in the longitudinal direction is small, the copying characteristics are satisfactory, and there is no white spot phenomenon, and uniform image quality can be obtained. On the other hand, also in the manufacturing process, the reel winding process is unnecessary, and the manufacturing cost is greatly simplified and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a conventional magnet roll, FIGS. 2 to 5 are schematic diagrams showing an embodiment of the magnet roll of the present invention, and FIG. 6 is a schematic diagram showing an example of the process of the present invention. FIG. 7 is a sectional view taken along the line AA of FIG. 6, and FIG. 8 is a schematic view showing the positional relationship between the electromagnet and the magnetic pole of the molding machine used in the examples. 1 ... Shaft 2 ... Magnet 2aI-2aIV ... Magnetic pole part 2bI-2bIV ... Inter-pole part 2A, 2B ... Extruded C-shaped cross-section magnet 3A, 3B ... Precision cut C-shaped cross-section magnet 4 ... Extrusion molding machine 5, 6 ... Guide rolls 7a, 7b ... Air gap 8 ... Soft magnetic yoke 9 ... Electromagnetic coil

Claims (3)

[Claims] 1. A magnet roll characterized by comprising three or more poles of anisotropy and having a magnetic pole portion of its cross section that is more convex than that between the pole portions. 2. The magnet roll according to claim 1, wherein a resin or rubber magnet having a substantially C-shaped cross section formed by extrusion molding is attached to the shaft. 3. A resin or rubber magnet material is formed by magnetic field orientation extrusion molding so that a magnetic pole portion is more convex than an interelectrode portion and a magnet having a substantially C-shaped cross-section has its C-shaped openings facing each other. A method for producing a magnet roll, comprising performing two-row extrusion, inserting a shaft between openings of the facing C-shaped magnet, and then adhesively fixing the C-shaped magnet so as to sandwich the shaft.