JP2003037006A - Method of manufacturing magnet piece and molding die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and speedily change the prescribed concentrating oriented position of magnetic powder without a substantial increase in facility cost and preparation man-hours. SOLUTION: A resin material to which magnetic powder is mixed is injected into the magnetic field of a molding cavity 10 formed by a magnetizing yoke 4 and a magnet piece where an outer peripheral face makes an arc-shaped face is manufactured. The arc-shaped face 9 of the molding cavity 10 is mode to relatively change with respect to the magnetizing yoke 4 according to the necessary concentrating oriented position of the magnetic powder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magnet piece for forming a magnet roll or other columnar or cylindrical plastic magnet having a circular outer contour by laminating a plurality of pieces, and a method for manufacturing the magnet piece. The present invention relates to a molding die used.

[0002]

2. Description of the Related Art For example, as a conventional molding technique for a magnet piece having a substantially fan-shaped cross section, an upper die 31 and a lower die 3 are used together with magnetic flux lines, as shown in the sectional view of FIG.
2, a molding cavity 33 having a substantially fan-shaped cross section is defined, and a magnetizing yoke 34 is attached to the upper mold 31.
The magnetic powder was blended into the molding cavity 33 in which the magnetic field was formed by the magnetizing yoke 34 when it was positioned and fixed to the upper die 31 in close proximity to the arc-shaped surface 33a that was formed on the above and contributed to the partition of the molding cavity 33. There is one that injects a resin material, which allows magnetic powder to be concentrated and oriented in a portion of the molded magnet piece corresponding to the tip surface of the magnetizing yoke 34.

[0003]

However, in such a conventional technique, for example, the cavity 33 shown in the figure is used.
When the magnetic powder is concentrated and oriented so as to be biased to the right side or the left side, for example, as shown in FIG. 4 together with the magnetic flux lines, the attachment position of the magnetizing yoke 34 to the upper die 31 is set to the arc-shaped surface 33a. Since it is necessary to displace the magnetic powder relative to each other, it is inevitable to newly manufacture the upper mold 31 each time the required concentrated orientation position of the magnetic powder changes.
There is a problem that both the equipment cost and the number of preparation steps are large.

The present invention has been made to solve the above problems of the prior art. The purpose of the present invention is to change the required concentrated orientation position of the magnetic powder. It is an object of the present invention to provide a method for manufacturing a magnet piece that can be simply and quickly performed without substantially increasing the equipment cost, the number of preparation steps, and the like, and a molding die used for the method.

[0005]

According to the method of manufacturing a magnet piece according to the present invention, a resin material mixed with magnetic powder is injected into a magnetic field of a molding cavity formed by a magnetizing yoke, and an outer peripheral surface has an arc shape. In manufacturing a magnet piece that has a surface, a cross-sectional shape that is almost fan-shaped, a semi-circular shape, etc.
The arc-shaped surface of the molding cavity is displaced relative to the magnetizing yoke in accordance with the required concentrated orientation position of the magnetic powder.

According to this, by simply changing the relative position of the arcuate surface of the molding cavity with respect to the magnetizing yoke, the magnetic powder can be simply and quickly placed at a desired position on the arcuate surface with one molding die. Since they can be concentrated and oriented, both the equipment cost and the number of preparation steps can be greatly reduced as compared with the conventional technology for manufacturing a new mold.

Further, the molding die of the magnet piece according to the present invention defines the molding cavity by the paired mold portions, and the molding cavity molds the magnet piece having an arcuate outer peripheral surface. In addition, a curved surface that specifies the arcuate surface of the molding cavity is provided on one mold part, for example, the upper mold, and a magnetizing yoke positioned corresponding to the curved surface is fixedly arranged, and the other mold part, for example, the lower mold. A rotative member having a substantially cylindrical shape is rotatably arranged around a central axis, and a dent portion for defining a molding cavity is formed on the rotative member in cooperation with the arcuate surface. It was done.

In this molding die, the rotating member arranged in the lower mold is rotated around the central axis thereof so that the upper die, and by extension, the arc-shaped surface of the upper die of the recessed portion provided in the rotating member. By changing the relative position to the specific curved surface, the arc surface area of the specific curved surface that contributes to the partition of the cavity also changes, and the arc surface of the molding cavity is displaced relative to the magnetizing yoke. Therefore, in the recess of the rotating member,
By appropriately selecting the relative position of the arcuate surface with respect to the specific curved surface, the above method can be easily and easily implemented.

In this molding die, preferably, a semicircular arc-shaped specific curved surface is formed on one of the mold portions. According to this, the forming cavity surrounded by the recess of the rotating member and the arcuate surface specific curved surface, in other words, the arcuate surface of the molding cavity can be relatively displaced with respect to the magnetizing yoke over a wide angle. .

Here, preferably, the other mold portion is provided with a position fixing means of the rotating member, and preferably, the other mold portion is provided with a rotating angle measuring means of the rotating member. According to the former, it is possible to prevent an unexpected rotational displacement of the recess of the rotating member, and to form the magnet piece in a desired posture, and according to the latter, the recess of the rotating member can be formed. It is possible to easily realize high positioning accuracy.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic line perspective view showing an embodiment of a molding die according to the present invention in a mold opening posture, and FIG. 2 is a longitudinal sectional view of the molding die in a mold closing posture.

The molding die shown here is composed of an upper die 1 and a lower die 2 which are paired up and down, and is used in the molding of a magnet piece having a substantially fan-shaped cross section. , A semicircular curved surface 3 for identifying the arc-shaped molding surface of the molding cavity, which corresponds to the arc-shaped outer peripheral surface of the magnet piece, is provided, and at the position corresponding to the curved surface 3, the tip end surface from the curved surface 3 is provided. The magnetizing yoke 4 is fixedly arranged at a slight distance. Here, as shown in FIG. 2, the magnetizing yoke 4 made of a permanent magnet is arranged in the non-magnetic material 5, and the upper surface thereof is backed up by the magnetic material 6.

On the other hand, a rotating member 7 having a substantially cylindrical shape is arranged on the lower mold 2 so as to be rotatable around its central axis, and in the figure, half of the rotating member is exposed from the surface of the lower mold. The exposed surface of 7 is provided with a recess 8 defining a molding cavity in cooperation with an arcuate surface identified by a portion of the curved surface 3.

Here, the arcuate surface which contributes to the partition of the molding cavity is displaced within the curved surface 3 in accordance with the position of the recess 8, and the recess 8 is, for example, as shown by the solid line in FIG. When facing straight up, the arcuate surface 9 is formed by the magnetizing yoke 4
While they are almost evenly present on both sides of the arc, when it is pivotally displaced to the right side of the figure as shown by the phantom line in the figure, the arcuate surface 9 is also biased to the right side of the figure. .

Therefore, with respect to the magnetizing yoke 4 which is always at a fixed position, the molding cavity 10 defined by the arcuate surface 9 and the recessed portion 8, that is, the arcuate surface 9, is accompanied by the rotational displacement of the recessed portion 8. The relative position will be changed.

Further, in such a molding die, preferably, the lower die 2 is provided with a position fixing means, for example, a fixing screw 11 for restraining the rotating member 7 in a desired posture with respect to the lower die 2, and also preferably. A means for measuring the rotation angle of the rotating member 7 with respect to the lower mold 2, for example, an angle scale 12 is provided at the shaft end of the rotating member 7.

Reference numerals 13 and 14 in the drawing respectively denote a runner and a gate, which, under the action of the magnetizing yoke 4, serve to introduce magnetic powder into the molding cavity 10 formed by closing the upper and lower molds 1 and 2. It functions to guide the compounded molten resin material. In addition, reference numeral 15 in FIG. 2 denotes a magnetic material that contacts the rotating member 7, and 16 denotes a non-magnetic material located on the side of the magnetic material 15.

When a magnet piece in which magnetic powder is concentrated and oriented at a desired position is formed by the above-described forming die, first, the rotating member 7 and, by extension, the recess 8 provided therein are rotated. The angle is accurately specified under the action of the angle scale 12, and the rotating member 7 is rigidly fixed to the lower mold 2 with the fixing screw 11, and then the upper and lower molds 1 and 2 are closed and mounted. The molding cavity 10 is defined at a required relative position with respect to the magnetic yoke 4, and then the molding cavity 1
Under the formation of a magnetic field by the magnetizing yoke 4, a resin material mixed with magnetic powder is pressure-filled into the inside of 0 with an injection nozzle (not shown).

The thus formed magnet piece having a substantially fan-shaped cross-section has a molding cavity 10
However, when it is at a relative position with respect to the magnetizing yoke 4 as shown by the solid line in FIG. 2, for example, the magnetic powder has a concentrated orientation portion in the central part of the fan shape. When in the position, on the left edge of the fan, and again
When the relative position is opposite to that shown by the phantom line, the magnetic powder has a concentrated orientation at the right end portion of the fan shape.

Thus, here, the rotating member 7 and the recessed portion 8 provided therein are rotationally displaced with respect to the curved surface 3 which specifies the arcuate surface 9 of the molding cavity 10, and as a result, the molding cavity 10 of the molding cavity 10 is displaced. Magnetizing yoke 4 with arcuate surface 9
Relative displacement with respect to the upper and lower dies, without changing or changing the upper and lower molds, the concentrated orientation position of the magnetic powder in the magnet piece can be changed easily, quickly, and as expected. Can be made.

Although the embodiment of the present invention has been described above based on the drawings, the cross-sectional shape of the magnet piece may be a semicircular shape, a quarter semicircular shape, or a semithin shape far thinner than the fan shape, as required. The shape may be a cylindrical shape, a quarter-cylindrical shape, or any other suitable shape.

[0022]

As described above, according to the present invention, it is possible to change the concentrated orientation position of the magnetic powder in the magnet piece as required without substantially increasing the equipment cost and the number of preparation steps.
It can be done simply and quickly.

[Brief description of drawings]

FIG. 1 is a schematic line perspective view showing an embodiment of a molding die according to the present invention in a mold opening posture.

FIG. 2 is a vertical sectional view of the mold shown in FIG. 1 in a mold closed state.

FIG. 3 is a vertical cross-sectional view showing a conventional molding die.

FIG. 4 is a vertical cross-sectional view showing another conventional molding die.

[Explanation of symbols]

1 Upper mold 2 Lower mold 3 curved surface 4 Magnetizing yoke 5,16 Non-magnetic material 6,15 Magnetic material 7 Rotating member 8 depressions 9 arc surface 10 Mold cavity 11 fixing screw 12 angle scale

Claims (5)

[Claims] 1. When manufacturing a magnet piece having an arcuate outer peripheral surface by injecting a resin material mixed with magnetic powder into a magnetic field of a molding cavity formed by a magnetizing yoke, A method of manufacturing a magnet piece, wherein the arcuate surface of a molding cavity is displaced relative to a magnetizing yoke in accordance with a required concentrated orientation position. 2. The molding cavity is defined by mold parts that are paired with each other, and the molding cavity defines the molding cavity.
A molding die for molding a magnet piece having an arcuate outer peripheral surface, wherein a curved surface that specifies the arcuate surface of a molding cavity is provided on one of the mold parts, and a magnetizing yoke positioned corresponding to the curved surface is provided. A rotating member having a substantially cylindrical shape is fixedly disposed on the other mold part so as to be rotatable around a central axis, and the rotating member is provided with a molding cavity in cooperation with the arcuate surface. A mold for forming a magnet piece, which is formed by forming a recessed portion that divides the magnet. 3. The molding die for a magnet piece according to claim 2, wherein a specific curved surface of a semi-circular arc surface is formed on one of the mold portions. 4. The molding die for a magnet piece according to claim 2 or 3, wherein a position fixing means for the rotating member is provided on the other die portion. 5. The molding die for a magnet piece according to claim 2, wherein a turning angle measuring means of the turning member is provided on the other die part.