JPH0596577A - Method and device for injection-molding anisotropic resin magnet - Google Patents

Abstract

PURPOSE:To form a symmetric magnetic field in a cavity without forming a magnetic circuit in a mold in specific constitution. CONSTITUTION:Exciting coils 4a, 4b are disposed on the side faces of the fixed plate 3a and movable plate 3b of a mold clamping device 3 respectively. Each exciting coil 4a, 4b is connected to each power unit 5a, 5b respectively while each power unit 5a, 5b is connected in parallel with a controller 7, and current values and the conduction time can be controlled respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for injection molding an anisotropic resin magnet.

[0002]

2. Description of the Related Art Conventionally, the following methods are known as injection molding methods for anisotropic resin magnets.

As shown in FIG. 4 or FIG. 5, a mold having a cavity 12 by the mold clamping device is used by using an injection molding machine in which a fixed plate and a movable plate of the mold clamping device are provided with exciting coils for generating magnetic fields, respectively. After the mold 11 is clamped, the exciting coil is energized with the same current value to make the cavity 12
While forming a magnetic field inside, injecting a molten resin magnet material containing anisotropic magnetic powder into the cavity, while the molten resin magnet material during the filling step and the pressure holding step is not cooled and solidified, The magnetic powder is oriented in the direction of the magnetic field.

In this case, the orientation of the anisotropic resin magnet can be axial orientation or radial orientation, but when the magnetic flux lines 18a are axially oriented as shown in FIG. 4, each exciting coil is energized in the same direction. When the magnetic flux lines 18b are radially oriented as shown in FIG. 5, a desired magnetic field is formed by energizing each exciting coil in the opposite direction.

[0005]

SUMMARY OF THE INVENTION In the above conventional technique,
Since each excitation coil is connected in series to the same power source, there is a limit to the symmetry of the magnetic field in the cavity. Especially in the case of radial compounding, the magnetic circuit in the mold can be devised to make the magnetic field symmetrical in the cavity. Since it is difficult to form a magnetic field, there is a problem that the orientation of the anisotropic resin magnet cannot be made symmetrical.

The present invention has been made in view of the above-mentioned problems of the prior art, and enables a symmetrical magnetic field to be formed in the cavity without a special configuration of the magnetic circuit in the mold. An object of the present invention is to realize an injection molding method for anisotropic resin magnets and an apparatus therefor.

[0007]

In order to achieve the above object, in the injection molding method for anisotropic resin magnets according to the present invention, a fixed plate and a movable plate of a mold clamping device are provided with exciting coils for generating magnetic fields, respectively. Using an injection molding machine, after clamping a mold having a cavity by the mold clamping device, while energizing the exciting coil to form a magnetic field in the cavity,
In an injection molding method of injecting a molten resin magnet material containing anisotropic magnetic powder into the cavity and orienting the magnetic powder in the direction of the magnetic field, current values and energization of each of the exciting coils are performed. By controlling the time separately, a symmetrical magnetic field is generated in the cavity.

Further, the injection molding apparatus for anisotropic resin magnets of the present invention is an injection molding machine in which a fixed plate and a movable plate of a mold clamping unit are provided with exciting coils for generating magnetic fields, each of the exciting coils being It is characterized in that it is provided with a control device which is respectively connected to different power supply devices and which can separately control the current value and the energization time of each power supply device.

[0009]

When the cavity is not located in the center of the mold, that is, not located in the center between the exciting coils, the exciting coils are energized with different current values so that the magnetic field is generated in the center of the cavity. Position the plane of symmetry to create a symmetrical magnetic field in the cavity.

[0010]

Embodiments of the present invention will be described with reference to the drawings.

First, an embodiment of the injection molding apparatus for anisotropic resin magnets of the present invention will be described. FIG. 1 is a schematic front view of the present embodiment, which is one end side (left side in the drawing) on the bed 9.
The mold clamping device 3 is disposed in the mold, and the injection device 6 is disposed in a portion facing the mold clamping device 3, that is, on the right side in the drawing.

The mold clamping device 3 connects the mold clamping housing 3c and the fixed platen 3a fixed to the bed 9, and connects them 4
A toggle mechanism 3 driven by a movable plate 3b guided by a book tie bar-3d and reciprocally movable in its axial direction, a fluid pressure cylinder 3f for reciprocating the movable plate 3b, and the like.
Exciting coils 4a and 4b are provided on the side surfaces of the fixed platen 3a and the movable platen 3b, respectively.

Each exciting coil 4a, 4b is connected to another power supply device 5a, 5b, respectively, and each power supply device 5a, 5b is connected in parallel to the control device 7 for different current values and energization times. It is configured to be separately controllable.

Next, the process of the first embodiment for producing the anisotropically oriented anisotropic resin magnet will be described.

The fixed platen 3a and the movable platen 3b of the mold clamping device 3 shown in FIG.
The mold 1 having the above is attached and the mold is clamped. On the other hand, the injection device 6 plasticizes the resin magnet material containing the magnetic powder having the easy axis of magnetization.

Then, the excitation coils 4a, 4b are energized in the same direction by the power supplies 5a, 5b to form an axial magnetic field in the cavity, and the molten resin magnet material is injected into the cavity to complete the filling. Post-holding pressure is applied. This energization is controlled by the control device 7 by the exciting coil 4b on the movable platen side.
Is controlled so that the value of the current flowing through the coil is larger than the value of the current flowing through the exciting coil 4a on the fixed board side.

As a result, the magnetic flux lines 8a are formed as shown in FIG. Is formed.

In the meantime, that is, in the cavity 2
While the molten resin magnet material is not completely cooled and solidified therein, the magnetic powder in the resin magnet material is axially oriented. After cooling and solidification, the mold 1 is opened to take out the anisotropically oriented anisotropic resin magnet molded product.

In the present embodiment, even if the magnetic circuit in the die 1 is not specially structured, the values of the currents flowing through the exciting coils 4a and 4b are made different, and the axial symmetrical in the cavity 2 is obtained. By forming an oriented magnetic field, a symmetrical axially oriented anisotropic resin magnet can be formed.

Next, the process of the second embodiment for producing a radially oriented anisotropic resin magnet will be described.

The present embodiment is different from the first embodiment only in the steps described below, and the other steps are the same.

In this embodiment, the exciting coils 4a and 4b are energized in opposite directions. This energization is controlled by the control device 7 so that the value of the current flowing through the exciting coil 4b on the movable plate side is greater than the value of the current flowing through the exciting coil 4a on the fixed plate side.

As a result, the magnetic flux lines 8b as shown in FIG. 3 are formed, and the plane of symmetry of the magnetic field shifts to the fixed platen side so that it is located at the center of the cavity 2 and a symmetrical radial magnetic field is formed in the cavity 2. It In this embodiment, the cavity 2
While the molten resin magnet material is not completely cooled and solidified therein, the magnetic powder in the resin magnet material is radially oriented. Then, after cooling and solidification, the mold 1 is opened to take out a radially oriented anisotropic resin magnet molded product.

In this embodiment, a symmetrical radially oriented magnetic field can be formed in the cavity 2 to form a symmetrical radially oriented anisotropic resin magnet.

[0025]

Since the present invention is configured as described above, it has the following effects.

By making a difference between the values of the currents flowing through the fixed-side exciting coil and the movable-side exciting coil, a symmetric plane of the magnetic field is positioned in the center of the cavity to form a symmetric magnetic field.
An anisotropic resin magnet having a symmetrical orientation can be manufactured.

When each exciting coil is energized in the opposite direction from that at the time of orientation for demagnetization after injection molding, the magnetic field formed in the cavity has a direction different from that at the time of orientation. This is completely opposite, and only the size can be reduced, and more effective demagnetization in the mold can be performed.

[Brief description of drawings]

FIG. 1 is a schematic front view of an injection molding machine of the present invention.

FIG. 2 is an explanatory diagram showing an alignment state of a magnetic field at the time of axial alignment of the first embodiment.

FIG. 3 is an explanatory diagram showing an alignment state of a magnetic field at the time of radial alignment of the second embodiment.

FIG. 4 is an explanatory view showing an alignment state of a magnetic field at the time of axial alignment of a conventional example.

FIG. 5 is an explanatory diagram showing a magnetic field alignment state during radial alignment in a conventional example.

[Explanation of symbols]

 1 Mold 2 Cavity 3 Mold Clamping Device 3a Fixed Plate 3b Movable Plate 4a, 4b Excitation Coil 5a, 5b Power Supply Device 6 Injection Device 7 Control Device 8a, 8b Magnetic Flux Line 9 Bed

Claims (2)

[Claims] 1. An injection molding machine in which an exciting coil for generating a magnetic field is provided on each of a fixed platen and a movable platen of a mold clamping device,
After the mold having the cavity is clamped by the mold clamping device, the exciting coil is energized to form a magnetic field in the cavity and a molten resin magnet containing anisotropic magnetic powder in the cavity. In an injection molding method in which a material is injected to orient the magnetic powder in the direction of the magnetic field, a symmetrical magnetic field is generated in the cavity by separately controlling the current value and energization time of each of the exciting coils. An injection molding method for an anisotropic resin magnet, which comprises: 2. An injection molding machine in which an exciting coil for generating a magnetic field is provided on each of a fixed platen and a movable platen of a mold clamping device, wherein each of the exciting coils is connected to a separate power supply device, and An injection molding device for an anisotropic resin magnet, comprising a control device capable of separately controlling a current value and an energization time of each power supply device.