JPS6334905A - Magnet roll - Google Patents

Abstract

PURPOSE:To accurately and easily obtain poles of arbitrary number with high magnetic force by engaging pole pieces formed with projections on the sector- shaped sides of the pieces oriented from the circular-arc state of sector-shaped section to both sector-shaped sides and inner periphery with pole pieces formed with grooves to be magnetized. CONSTITUTION:Pole pieces 13 so molded in sector-shaped section as to be oriented from the sector-shaped circular-arc part to both section-shaped sides and inner periphery have engaging projections 14, 14' longitudinally on the sides, and pole pieces 15 are similarly molded, but have grooves 16, 16' on the sides. Radial projections 14, 14' and radial grooves 16, 16' are formed at the similar pole pieces 13, 15, respectively. The obtained pieces 13, 15 are demagnetized, the grooves 16, 16' of the pieces 15 are sequentially slid to the projections 14, 14' of the pieces 13 with a shaft 22 as a center to be assembled, and a magnet roll after the assembling is magnetized in response to the poles of the outer periphery. Thus, the number of the poles can be arbitrarily selected to provide the roll having high magnetic force.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnet roll used in electrophotographic developing devices, cleaning devices, etc., such as PPC copying machines and facsimile IJs.

Conventional technology Conventionally, these magnet rolls were constructed using rod-shaped or cylindrical sintered ferrite magnets on the outer periphery of the roll shaft, but sintered ferrite has a high density and is heavy, and has a large shrinkage and is prone to warping and distortion. It is difficult to achieve dimensional accuracy such as
Due to its brittleness, it has drawbacks such as chipping and cracking, and poor workability.Recently, however, it has been constructed using resin magneto, which is a composite of rubber or resin-based ferrite powder. Ta.

The conventional technology for a magnet roll using such a composite resin magnet material is to mechanically orient the axis of easy magnetization of the ferrite powder 2 in the resin 1 in the Y1 direction using a rolling roller 3 or the like, as shown in Fig. 7. Several sheets of rolled belt 4 are stacked together as shown in FIG. 8A and press-formed into a fan shape as shown in FIG. 8B, and the molded bodies 6 of FIG.
(C is separated to obtain the magnetic pole piece 6, which is shown in Fig. 8F.
As shown in the figure, it was constructed by bonding it to the shaft 7 using an adhesive. Furthermore, as shown in FIG. 9, a resin magnet material is injected into a magnetic field forming mold 11 having a cylindrical cavity 10i made of a magnetic metal material 8 and a non-magnetic metal material 9 with a metal shaft 7 arranged in the center. There is a material 8 that is made into a magnet roll by passing a current through a magnetic field generating coil 12 provided around the material 8 and performing magnetic field shaping.

Problems to be Solved by the Invention In such a conventional configuration, sufficient magnetic force can be obtained because the axis of easy magnetization of the ferrite powder is oriented to the grid, but when the magnetic pole piece 6 is attached, the polar Misalignment, bending, etc. occur, making it difficult to bond with high precision, resulting in extremely poor productivity. In the latter case, the process can be simplified because the shaft 7 is integrally molded around the shaft 7 with a resin magnet, but if the required number of magnets or the magnetic pole position is asymmetrical, the mold yoke or the magnetic field generating coil 12 may be required. There were major problems in that space was limited, the number of magnetic poles was limited, and only magnetic rolls with low magnetic force could be obtained.

Means for Solving the Problems The present invention solves these problems, and provides a magnetic pole having a fan-shaped cross section, an arc shape, and a magnetic pole piece that is oriented on both sides of the fan shape and on the inner periphery thereof, and that protrusions are provided on the fan-shaped side faces of the magnetic pole piece. A piece and a magnetic pole piece provided with a groove are fitted together to be magnetized, and the protrusion and groove are provided in the longitudinal direction or in the radial direction.

Effect With the above structure, the number of magnetic poles can be arbitrarily selected and a magnetic roll with high magnetic force can be obtained.

EXAMPLES Below, the present invention will be explained with reference to the examples shown in FIGS. 1 to 6. In FIG. 3, 13 is a molded product having a fan-like cross section and oriented from the fan-shaped arc portion to both sides and inner circumference of the fan-like shape. A magnetic pole piece with a protrusion 14.14'i on the side for fitting.
It has in the longitudinal direction. One of the magnetic pole pieces 15 is molded in the same manner, but is provided on the side surface of the groove 16.18''i in order to fit into the protrusion 14.14'i.Furthermore, FIG. 13 and 15 are provided with longitudinal protrusions 14 and 14' and longitudinal grooves 16 and 16'.

These magnetic pole pieces 13 and 16 are made of a composite resin magnet material made of ferrite powder and a polymer material, and as shown in FIG. A magnetic field generating coil 21 is provided around a mold 2o having a mold 2o having a magnetic field generating coil 21, and is oriented by passing a current through the magnetic field generating coil 21 during injection molding or extrusion molding.

Each of the magnetic pole pieces 13.15 thus obtained is demagnetized, and the protrusions 14, 14' of the magnetic pole piece 13 are inserted into the grooves 16.16 of the magnetic pole piece 16 with the shaft 22 as the center.
”i Slide in order to assemble.

The magnet roll after assembly is shown in FIGS. 1 and 2. After assembly, the magnet roll is completed by magnetizing it in accordance with the number of outer circumference magnets. When assembling, the protrusions 14 and 14' of the magnetic pole piece 13 and the groove 16 of the magnetic pole piece 16 are
．． 16'i It is possible to easily assemble any number of magnetic poles by simply sliding the magnetic poles, and the pole positions do not shift or bend. Furthermore, since the magnetic force generated by magnetization firmly joins the magnetic pole pieces 13 and 15, they will not come off even without using an adhesive. As shown in Fig. 5, the magnetic pole piece is oriented from the fan-shaped arc part Z to the fan-shaped side surface α and inner peripheral surface γ direction, so the magnetic force is concentrated at the magnetic pole center 2, making it possible to produce a magnetic roll with high magnetic force and high dimensional accuracy. You can get a good deal.

According to the present invention, productivity is improved by about 30% compared to bonding using conventional adhesives. It was confirmed that the magnetic force was improved by 16 to 20% compared to an integrally molded product.

In the embodiments described above, the protrusions 14, 14' and the grooves 16, 16' are square in shape, but are not limited to round, triangular or multicolored shapes. Also, the projections 14 do not necessarily have to be parallel, as shown in FIG.
, it is also possible to add a taper to 14'.

Effects of the Invention As is clear from the above explanation, the magnet roll according to the present invention has a high magnetic force and can easily obtain a desired number of magnetic poles with high precision, making it an industrially valuable product.

[Brief explanation of the drawing]

FIG. 1 is a side view showing one embodiment of the magnet roll of the present invention, FIG. 2 is a front view of another embodiment, FIG. 3 is a perspective view of the magnetic pole piece of the magnet roll shown in FIG. The figure is a perspective view of the magnetic pole piece of the magnet roll shown in Figure 2;
FIG. 6 is a cross-sectional view of a magnetic field forming mold for molding the same magnetic pole piece, FIG. 8 is a perspective view of a magnetic pole piece of another embodiment, and FIG. 7 is an explanation of the process of obtaining a rolled sheet of a conventional composite resin magnet. Figures 8-F are explanatory diagrams showing the manufacturing process of a conventional magnet roll, and FIG. 9 is a cross-sectional view of a magnetic field forming die for producing another conventional magnet roll. 13.15...Magnetic pole piece, t 4 jl 4
'... Protrusion, 16, 16'... Groove, 22... Shaft. Name of agent: Patent attorney Toshio Nakao and 1 other person
1 Figure 2 Figure 5 Figure 7 Figure 8

Claims (3)

[Claims] (1) A plurality of elongated magnetic pole pieces having a fan-shaped cross section are provided on the outer periphery of the shaft, and protrusions are provided from the circular arc portion of the fan-shaped cross section to both fan-shaped sides and the fan-shaped side surface of the magnetic pole piece oriented to the inner periphery. A magnet roll that is magnetized by fitting together a magnetic pole piece with a groove and a magnetic pole piece with a groove. (2) The magnet roll according to claim 1, wherein the protrusions and grooves of the magnetic pole piece are provided in the longitudinal direction. (3) The magnet roll according to claim 1, wherein the protrusions and grooves of the magnetic pole piece are provided in the radial direction.