JP4097121B2 - Magnet roll manufacturing method and magnetic pole piece mold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a magnet roll for developing a magnetic brush of, for example, an electrophotographic copying machine or a facsimile receiver.
[0002]
[Prior art]
Conventionally, there has been provided a magnet roll (1) in which a plurality of magnetic pole pieces (3) having a substantially fan-shaped cross section in the short-side direction are radially bonded around a shaft (2). When manufacturing the magnetic pole piece (3), as shown in FIG. 6, a manufacturing method in which the magnetic pole pieces (3) are formed one by one using a single mold (4A) is generally used.
[0003]
[Problems to be solved by the invention]
However, the conventional method of manufacturing the magnet roll (1) has a problem that it takes time to manufacture the magnetic pole piece (3) because the magnetic pole pieces (3) are formed one by one.
[0004]
[Means for Solving the Problems]
As a means for solving the above-described conventional problems, the present invention performs injection molding of a plurality of magnetic pole pieces (3) having a substantially fan-shaped cross-sectional shape in a magnetic field by a single mold, and the plurality of magnetic poles In the manufacturing method of the magnet roll (1) in which the pieces are bonded radially around the shaft (2), the arc-side end corners of each magnetic pole piece (3) are cut off, and the mold (4) A split type having a plurality of cavities (5) corresponding to the shape of the magnetic pole piece (3), and the parting line PL of the split type is cut off at both corners of the arc end of the adjacent cavity (5) is on a line connecting each other, each line segment, Ri Contact is set to so that near-collinear by adjusting the part providing the cavity (5) position of the trimmed shapes, further the cavity ( The orientation yoke (6) or Provides a method for producing a magnet roll (1) in which permanent magnets are arranged.
Furthermore, the present invention provides a magnet roll (1) for injection-molding a plurality of magnetic pole pieces (3) having a substantially fan-shaped cross-sectional shape in a magnetic field by a single mold as a means for solving the above conventional problems. The magnetic pole piece mold (4) is formed by cutting off the arc-side end corners of each magnetic pole piece (3), and the magnetic pole piece mold (4) is formed on each magnetic pole piece (3). This is a split type having a plurality of cavities (5) corresponding to the shape, and the parting line PL of the split type is on a line segment that cuts off both corners of the arc side end of adjacent cavities (5) and connects each other. There, each line segment, Ri Contact is set to so that near-collinear by adjusting the part providing the cavity (5) position of the trimmed shape, further an arc end upper side of the cavity (5) Is a magnet with an orientation yoke (6) or permanent magnet. A mold (4) for a trawl pole piece is provided.
[0005]
[Action]
In the present invention, since a plurality of magnetic pole pieces (3) can be injection-molded in a magnetic field at a time with a single mold (4), the magnet roll (1) can be manufactured without much trouble. I can do it.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described with reference to an embodiment shown in FIGS.
In this embodiment, there are six magnetic pole pieces (3) in which the cross-sectional shape in the short direction is substantially fan-shaped around the cylindrical shaft (2) as shown in FIG. ) Is a method of manufacturing a magnet roll (1) bonded radially, and the six magnetic pole pieces (3) are injection-molded in a magnetic field by one mold (4) as shown in FIG. The case where it does is illustrated.
[0007]
The magnetic pole piece (3) is manufactured by injection molding a magnetic material powder and a resin binder in a magnetic field using the mold (4). Examples of the magnetic material powder include ferrite powder, A mixture of rare earth metal powders such as Nd and iron group metal powders such as Fe, Co and Ni is used, and as a resin binder, for example, polyamide, polyethylene, polypropylene, epoxy resin, ethylene ethyl acrylate (EEA) or the like is used. The
[0008]
As shown in FIGS. 1 and 2, the mold (4) includes an upper mold (41) and a lower mold (42), and an upper base (43) and a lower base (44). (41) and a lower mold (42) are divided molds provided with six cavities (5) corresponding to the shape of each magnetic pole piece (3). The ring line PL is on the line segment connecting the cut-out corners of the adjacent cavity (5) and connecting each other, and each line segment is set to be on the same line, the arc side of the cavity (5) An orientation yoke (6) for orienting the axis of easy magnetization of the magnetic material powder of the magnetic pole piece (3) in a desired direction is disposed on the upper end side, and further around the mold (4). A magnetic field generating coil (not shown) is arranged.
[0009]
When the magnet roll (1) is manufactured, a mixture of the magnetic material powder and the resin binder is injection-molded in a predetermined magnetic field using the mold (4) and the six magnetic pole pieces (3) are formed. After manufacturing, each magnetic pole piece (3) is demagnetized and bonded around the shaft (2) radially, and then each magnetic pole piece (3) is magnetized to produce a magnet roll (1).
[0010]
In this way, by manufacturing the magnetic pole piece (3) using the mold (4), six magnetic pole pieces (3) are injection-molded at a time in a magnetic field by one mold (4). Therefore, the magnet roll (1) can be manufactured without taking time and effort.
Further, since the parting line PL of the mold (4) is set to be on the same line, the processing of the molding surface of the mold (4) becomes very easy, and the mold (4) Since the processing accuracy of the molding surface can be greatly improved, burrs are not generated, and the molding accuracy of the magnetic pole piece (3) can be improved and the life of the mold (4) can be extended.
Further, the shape of each cavity (5) of the mold (4) corresponds to the shape of each magnetic pole piece (3), the cross-sectional shape in the short direction is substantially fan-shaped, and both corners on the arc side end are cut off. Since the parting line PL of the mold (4) is set to be on the line segment connecting the cut-off ends of the arc-side end corners of the adjacent cavity (5), the part of the cut-off shape By adjusting the position where the cavity (5) is provided, the parting line PL is set to be on the same line, and the space for the alignment yoke can be secured without the occurrence of an undercut portion. It becomes possible to increase the degree of design freedom.
[0011]
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[0012]
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[0013]
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[0014]
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[0015]
As mentioned above, although the embodiment of the present invention has been described by way of examples, the scope of the present invention is not limited to these, and can be changed or modified in accordance with the target value within the scope described in the claims. Is possible.
[0016]
【The invention's effect】
In the present invention, since a plurality of magnetic pole pieces can be injection-molded in a magnetic field at a time with a single mold, a magnet roll can be manufactured without taking time and effort.
[Brief description of the drawings]
1 to 3 show an embodiment of the present invention.
FIG. 1 is an explanatory sectional view of a mold.
FIG. 2 is a partially enlarged sectional view of a mold.
FIG. 3 is an explanatory sectional view of a magnet roll.
FIG. 4 is an explanatory sectional view of a conventional mold.
[Explanation of symbols]
1 Magnet roll
2 shaft
3 Magnetic pole piece
4 Mold
5 cavity
6 Orientation yoke PL Parting line

Claims (2)

In the method of manufacturing a magnet roll, a plurality of magnetic pole pieces having a substantially fan-shaped cross section in the short direction are injection-molded in a magnetic field by a single mold, and the plurality of magnetic pole pieces are bonded radially around a shaft.
The arc-side end corners of each pole piece are cut off,
The mold is a split mold having a plurality of cavities corresponding to the shape of each magnetic pole piece,
The split of the parting line is located on the connecting the cut off mutual arcuate end corners of the adjacent cavity segments,
Each segment, Ri Contact is set to so that near-collinear by adjusting the part providing the cavity position of the cut off shape,
Further, an orientation yoke or a permanent magnet is arranged above the arc side end of the cavity. A mold for a magnetic pole piece of a magnet roll in which a plurality of magnetic pole pieces having a substantially fan-shaped cross section in a short direction are injection-molded in a magnetic field by a single mold,
The arc-side end corners of each pole piece are cut off,
The magnetic pole piece mold is a split mold having a plurality of cavities corresponding to the shape of each magnetic pole piece,
The split of the parting line is located on the connecting the cut off mutual arcuate end corners of the adjacent cavity segments,
Each segment, Ri Contact is set to so that near-collinear by adjusting the part providing the cavity position of the cut off shape,
Further, a magnetic pole piece mold for a magnet roll, wherein an orientation yoke or a permanent magnet is arranged on the upper side of the arc side end of the cavity.