JPH0521382Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a molding machine used for injection molding of plastic magnets formed by adding synthetic resin to magnetic powder.

[Prior Art] When injection molding anisotropic plastic magnets, it is necessary to apply a magnetic field to the mold during the molding process. For this reason, an injection molding machine is used in which both the fixed platen and the movable platen are equipped with excitation coils for generating magnetic fields.

This type of injection molding machine was developed in 1980.
There is one described in Publication No. 158727.

This injection molding machine has blocks made of ferromagnetic material placed opposite each other in the center of the fixed platen and the movable platen, and excitation coils are wrapped around the outer periphery of these blocks.
The entire excitation coil is covered by a cover made of non-magnetic material that also serves as a mold mounting plate and is fixed to the block.

[Problems to be Solved by the Invention] In the above-mentioned conventional technology, austenitic stainless steel, which has a lower thermal conductivity than general template materials and is difficult to process, is used as the cover made of a non-magnetic material. Therefore, it is difficult for the heat generated by the excitation coil to escape, and this may cause the excitation coil to overheat and break. It also has problems such as increased costs due to the difficulty of processing.

This idea was devised to solve the above problem, and its purpose is that even if the mold mounting plate is used as a member that covers the inside of the board together with the excitation coil, the heat generated from the excitation coil will not be absorbed inside. It is an object of the present invention to provide a new plastic magnet injection molding machine that is less likely to be crowded and can reduce costs.

[Means for Solving the Problems] This invention for the above-mentioned purpose includes core blocks made of a magnetic metal material placed opposite to each other in the center of a stationary plate body and a movable plate body formed of a magnetic metal material. At the same time, an excitation coil is attached to the core block, and a mold mounting plate made of a magnetic metal material without tie bars at the corners of the board is fixed to the core block, and the inside of the fixed board and the movable board are excited by the mold mounting plate. The conventional problems are solved by coating the coil together with the coil.

[Function] In the above configuration, when the molds are attached to both mold mounting plates and the excitation coil is energized in the mold clamp state, the core block - fixed platen body - tie bar - movable platen body - core block - mold mounting plate - mold - mold A closed loop is formed in the order of the mounting plates, and magnetic flux is generated there. Further, the heat generated from the excitation coil is radiated from between the board and the mold mounting plate.

[Example] In the figure, 1 and 2 are fixed plate bodies installed oppositely on the machine base 3,
Tie bars 4, 4 made of magnetic metal material inserted into the four corners
They are connected by A movable platen 5 is slidably inserted and supported by the tie bars 4, 4, and is connected to a ram 7 of a mold clamping cylinder 6 provided on the fixed platen 1.

The fixed platen body 2 and the movable platen body 5 are formed of a magnetic metal material, and in the center of their opposing sides,
Circular core blocks 8 and 9 made of magnetic metal material are integrally attached. These core blocks 8, 9
Excitation coils 10 and 11 are wrapped around the outer periphery of the core blocks 8 and 9, and mold mounting plates 12 and 13 made of magnetic metal material are mounted on the end faces of the core blocks 8 and 9, and spacers 14 are provided between them and the core blocks 8 and 9. It's worn.

The four corners of the mold mounting plates 12, 13 are formed into arc-shaped cutouts 12a, 13a to avoid contact with the tie bars 4, 4, and thereby the tie bars 4, 4 at the corners of the board are The insides of the fixed platen 2 and the movable platen 5 are covered with excitation coils 10 and 11 as well as mold mounting plates 12 and 13, except for.

A fixed mold 15 and a movable mold 16 are attached to the mold mounting plates 12 and 13, and an injection device 17 is mounted at the center of the fixed plate body 2, the core block 8, and the mold mounting plate 12.
A nozzle insertion hole 18 is provided therethrough. Similarly, a housing hole 20 for an ejecting device 19 is provided through the center of the movable platen 5, core block 9, and mold mounting plate 13.

In the above configuration, since the tie bars 4, 4 and the mold mounting plates 12, 13 are separated by the cutout parts 12a, 13a, the excitation coils 10, 11 are energized in the mold clamping state shown in FIG. When this is done, the core block 8 - fixed platen 2 - tie bars 4, 4 - movable platen 5 - core block 9 - mold mounting plate 13 - movable mold 1
A closed loop of 6-fixed mold 15-mold mounting plate 12 is formed, and magnetic flux is generated there.

Under these conditions, when a molding material made by adding synthetic resin as a binder to magnetic powder of ferrite or rare earth metal is injected and filled into a mold, the axis of easy magnetization of the magnetic powder is oriented in the direction of magnetic flux flow. By cooling and solidifying, it is physically confined and becomes a molded anisotropic plastic magnet.

In the example shown in FIG. 4, the cutouts 12a and 13a of the mold mounting plates 12 and 13 are formed large, and a nonmagnetic member 21 made of ceramic, nonmagnetic metal material, etc. is provided on the edge of the cutouts 12a and 13a, and the tie bars 4 and 13 are and mold mounting plate 1
This is what is shown when isolation from 2 and 13 is further ensured.

FIG. 5 also shows an outer cylinder 22 and an inner cylinder 2 made of non-magnetic material that fit together around the tie bars 4, 4.
3, the outer cylinder 22 is placed on the fixed plate body side, and the inner cylinder 23 is placed on the fixed plate body side.
shows the case where they are fixed to the movable platen body side and separated from the mold mounting plate side.

[Effects of the invention] As described above, this invention has a structure in which the fixed platen 2 and the movable platen 5, each made of a magnetic metal material, have a
Core blocks 8 and 9 made of magnetic metal material are arranged opposite each other, and an excitation coil 1 is arranged around the outer periphery of these core blocks 8 and 9.
0 and 11, and mold mounting plates 12 and 13 made of magnetic metal material with corners removed are fixed to the core blocks 8 and 9, and the mold mounting plates 12 and 13 connect the fixed platen body 2 and the movable platen. Tie bars 4, 4 on the inside of body 5
Since the excitation coils 10 and 11 are covered except for the parts, the mold mounting plate does not act as a return yoke even if the mold mounting plate is made of a magnetic metal material.

In addition, since there is a gap between the board and the mold mounting plate at the cutout, the heat generated by the excitation coil escapes to the outside through the gap, and the excitation coil is covered by the mold mounting plate. Even if the coil is heated, heat will not accumulate inside the coil, and therefore, it is possible to prevent the excitation coil from being overheated and disconnected due to heat generation.

Furthermore, since a magnetic metal material, which is easier to process than a non-magnetic metal material, can be used as the mold mounting plate, the cost of materials, processing, assembly, etc. is reduced, and it has the advantage of being cheaper than conventional materials.

[Brief explanation of the drawing]

The drawings show an embodiment of the plastic magnet injection molding machine according to this invention. Fig. 1 is a longitudinal sectional front view, Fig. 2 is a partially cutaway perspective view, and Fig. 3 is an inner surface of the fixed plate body side. FIG. 4 is an inner view of the stationary plate body side of another embodiment, and FIG. 5 is a partially vertical side view of another embodiment of the tie bar. 1, 2... Fixed plate body, 3... Machine base, 4... Tie bar, 5... Movable plate body, 8, 9... Core block, 10, 11... Excitation coil, 12, 13...
Mold mounting plate, 12a, 13a... missing part, 14...
Spacer, 15, 15... fixed type, 16... movable type, 21... non-magnetic member, 22... outer cylinder, 23
...Inner cylinder.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A core block made of a magnetic metal material is provided in the central part of a fixed plate body and a movable plate body formed of a magnetic metal material, and an excitation coil is wrapped around the outer periphery of these core blocks. At the same time, a mold mounting plate made of magnetic metal material with corners removed is fixed to the core block, and the mold mounting plate covers the inside of the fixed platen body and the movable platen body together with the excitation coil except for the tie bar portion. A plastic magnet injection molding machine characterized by: (2) The plastic magnet injection molding machine according to item 1, wherein the disk body and the mold mounting plate are connected by a spacer made of a non-magnetic metal material on the outside of the excitation coil. Machine. (3) In the plastic magnet injection molding machine described in item 1, the plastic magnet is characterized in that a non-magnetic member interposed between the tie bar and the mold mounting plate is provided in the missing portion of the mold mounting plate. Injection molding machine. (4) The plastic magnet injection molding machine according to item 1, wherein the tie bar is covered with an inner cylinder and an outer cylinder made of a non-magnetic material that fit together.