JPH023856Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a mold clamping device for a magnetic field injection molding machine.

(b) Conventional technology When injection molding anisotropic plastic magnets, it is necessary to apply a magnetic field during the molding process, but the mold clamping device of a conventional magnetic field injection molding machine has two It can be classified into two formats. That is, there are two types: one in which the coil is attached to the mold, and one in which the coil is placed away from the mold, for example on the outer periphery of a stationary platen and a movable platen.

(c) Problems to be solved by the invention In the case of a type in which a coil is attached to a mold, a dedicated coil is required for each mold, which increases the number of types of coils and increases costs. There is a point. In addition, in the case of a type in which the coil is placed away from the mold, there is no space around the mold periphery for the coil, the piping and wiring for temperature control of the mold becomes complicated, and the removal of the molded product is difficult. Workability also deteriorates, and productivity drops significantly.
In addition, if the coil is moved to take out the molded product, a device for moving the coil is required, and the time needed to move the coil is required, which lengthens the cycle time and reduces productivity. There is a problem with that. The present invention aims to solve the above problems.

(d) Means for solving the problems The present invention solves the above problems by arranging two coils around the outer periphery of each tie bar, one of which is attached to a fixed plate and the other to a movable plate. That is, the mold clamping device of the magnetic field injection molding machine according to the present invention has a fixed plate in which the casing on the inner diameter side and one end face side is made of a ferromagnetic material, and the casing on the outer diameter side and the other end face side is made of a nonmagnetic material. The inner diameter part of the side coil is fitted into the tie bar, and one end face is attached tightly to the fixed plate, and the casing on the inner diameter side and one end face side is made of ferromagnetic material, and the casing on the outer diameter side and the other end face side is made of ferromagnetic material. It is characterized in that the inner diameter part of the movable platen-side coil made of a non-magnetic material is disposed on the outer periphery of the tie bar so as to be movable in the axial direction, and one end face is attached to the movable platen in close contact with the movable platen. The tie bar is composed of an inner non-magnetic material part and a cylindrical ferromagnetic material part provided on the outer periphery of the tie bar, and the ferromagnetic material part can be made to have the minimum length necessary for the stroke of the movable platen. Note that the fixed platen side coil and the movable platen side coil may be respectively attached to all four tie bars, for example.
If the required magnetic flux density is small, it may be provided only on the minimum required number of tie bars.

(E) Effect When the mold is clamped and current is applied to the coil on the fixed platen side and the coil on the movable platen side, the tie bar surrounded by the coil on the fixed platen → the tie bar surrounded by the coil on the movable platen side. → Movable platen → Movable ferromagnetic material part → Cavity → Fixed ferromagnetic material part → Fixed platen → A closed magnetic path for the magnetic flux flow called the tie bar surrounded by the coil on the fixed platen side is formed, and A magnetic field can be applied to the molten resin to orient the magnetic powder. When the mold is opened and the movable platen moves, the movable platen side coil moves together with it. Therefore, no special device such as a hydraulic cylinder is required to move the coil. Also, no extra time is required for coil movement. The piping and wiring for controlling the temperature of the mold can be done in the same way as in a normal injection molding machine, and the molded product can also be taken out in the same way as in a normal case. There is no need for the mold to have a special structure for attaching the coil.

(F) Embodiments Hereinafter, embodiments of the present invention will be described based on FIGS. 1 to 4 of the accompanying drawings.

(First Embodiment) Figures 1 and 2 show the upper half of a mold clamping device of a magnetic field injection molding machine according to a first embodiment of the present invention. A fixed platen 10 and a movable platen 12 made of a ferromagnetic material are arranged so as to face each other, and the movable platen 12 is guided by tie bars 14 and can move toward or away from the fixed platen 10. Tie bar 1
4 has a non-magnetic material portion 14a on the inner circumference side and a cylindrical ferromagnetic material portion 14b on the outer circumference thereof. The ferromagnetic material portion 14b has a minimum length necessary for the stroke l of the movable platen 12. The ferromagnetic material portion 14b acts as a return yoke, and the non-magnetic material portion 14a performs the tie bar's original function of supporting the mold clamping reaction force. The movable platen 12 is movable by being guided by the tie bars 14 via the bushes 16. A fixed die 18 is attached to the fixed platen 10, and a movable die 20 is attached to the movable platen 12. The fixed mold 18 is composed of a non-magnetic material portion 18a and a ferromagnetic material portion 18b. Moreover, the movable mold 20 also has a non-magnetic material portion 20a and a ferromagnetic material portion 20a.
It is composed of b. Fixed type 18 and movable type 2
0 constitutes the cavity 22. A fixed plate side coil 24 is attached to the fixed plate 10. The fixed platen side coil 24 has its right end face fixed to the fixed platen 1.
0, and the inner diameter portion is fitted to the tie bar 14. In addition, the fixed plate side coil 24
In Fig. 1, the casing 24 on the right end side and the inner diameter side
The casing 24b on the left end side and the outer diameter side is made of a non-magnetic material. The casing 24b is for preventing magnetic flux from leaking. A movable platen side coil 26 is attached to the movable platen 12. The left end surface of the movable platen coil 26 in FIG. ,
The movable platen side coil 26 is movable in the axial direction with respect to the tie bar 14. The first coil 26 on the movable platen side
In the figure, the casing 26a on the left end side and the inner diameter side is made of a ferromagnetic material, and the casing 26b on the right end side and the outer diameter side is made of a nonmagnetic material. Note that the fixed plate side coil 24 and the movable plate side coil 26 may be attached to all of the tie bars 14, which are normally four, or may be attached to only the minimum required tie bars 14 when the required magnetic flux density is small. good.

FIG. 1 shows a state in which the fixed mold 18 and the movable mold 20 are brought into close contact with each other after the molds are clamped. When current is applied to the fixed plate side coil 24 and the movable plate side coil 26 in this state, the magnetic flux generated by these forms a closed magnetic path through the ferromagnetic material portion. That is, the closed magnetic path is as shown by the dotted line: ferromagnetic material portion 14b of tie bar 14 → movable platen 12 → ferromagnetic material portion 20b of movable mold 20 → cavity 22 → ferromagnetic material portion 18b of fixed mold 18 → fixed platen 10 → Passes through the ferromagnetic material portion 14b of the tie bar 14. When a molten plastic magnet is injected into the cavity 22 with a magnetic field generated in the cavity 22, the magnetic powder within the molten plastic magnet is aligned in the direction of easy magnetization of the magnetic powder. When the plastic is cooled and solidified in this state, a plastic magnet with an easy magnetization direction, that is, an anisotropic plastic magnet can be obtained. The molded product can be taken out as usual by stroking the movable platen 12. Movable plate side coil 26
moves together with the movable platen 12. Therefore, no special device or moving time is required to move the movable platen side coil 26. Fixed type 18 and movable type 2
0 can use a mold for plastic magnets having the same external structure as that of a general mold used for normal molding. Therefore, the work of attaching and removing the fixed mold 18 and the movable mold 20 can be carried out as usual by opening and closing the movable platen 12. The arrangement of mold temperature control piping, wiring, etc. can be done in the same manner as in a normal injection molding machine. The fixed platen side coil 24 and the movable platen side coil 26 are arranged separately and coaxially with the tie bar 14 and are miniaturized, so that internal resistance loss of the coils is reduced and power consumption is reduced. Further, in this embodiment, the tie bar 14 is connected to the non-magnetic material portion 14a.
and a ferromagnetic material portion 14b, only the ferromagnetic material portion 14b is used as a return yoke, and the length of the ferromagnetic material portion 14b is set to the minimum required length, so that leakage of magnetic flux can be reduced.

(Second Embodiment) FIG. 3 shows a second embodiment of the present invention. In this embodiment, all tie bars 14'' are made of ferromagnetic material to construct a magnetic circuit.Other configurations are the same as those shown in Figures 1 and 2.In this embodiment, tie bars 14'' The same effects as in the first embodiment can be obtained except that the leakage of magnetic flux slightly increases.

(Third Embodiment) FIG. 4 shows a third embodiment of the present invention. This third
In this embodiment, the directions of current flow in the fixed plate side coil 24 and the movable plate side coil 26 are reversed, and a magnetic circuit as shown by the dotted line in the figure is constructed. Thereby, a radial magnetic field can be created within the cavity 22.

(g) Effects of the invention As explained above, according to the invention, two coils are provided around the outer periphery of each tie bar, one coil is attached to the fixed platen, and the other coil moves together with the movable platen. Therefore, it is possible to obtain a magnetic field injection molding machine having good workability similar to that of a normal injection molding machine. This has resulted in problems such as the need for a coil for each mold, problems with the arrangement of mold temperature control pipes and wiring, problems with the workability of removing molded products, and problems associated with moving the coils. traditional problems can be solved.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a mold clamping device of a magnetic field injection molding machine which is the first embodiment of the present invention, and Fig. 2 is a diagram showing the -
FIG. 3, a cross-sectional view taken along the line, shows a second embodiment of the present invention. FIG. 4 shows a third embodiment of the present invention. 14... Tie bar, 14a... Non-magnetic material part,
14b...Ferromagnetic material part, 24...Fixed plate side coil, 24a, 24b...Casing, 26...Movable plate side coil, 26a, 26b...Casing.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. The inner diameter part of the coil on the stationary platen side, in which the casing on the inner diameter side and one end face side is made of ferromagnetic material, and the casing on the outer diameter side and the other end face side is made of nonmagnetic material. It fits into the tie bar and is attached with one end surface in close contact with the fixed plate, and the casing on the inner diameter side and one end surface side is made of ferromagnetic material, and the casing on the outer diameter side and the other end surface side is made of nonmagnetic material. A mold clamping device for a magnetic field injection molding machine in which the inner diameter part of a coil on the movable platen side is arranged movably in the axial direction on the outer periphery of the tie bar, and one end face is attached to the movable platen in close contact with the movable platen. 2 The tie bar is composed of an inner non-magnetic material part and a cylindrical ferromagnetic material part provided on its outer periphery, and the ferromagnetic material part is the minimum length necessary for the stroke of the movable platen. A mold clamping device for a magnetic field injection molding machine according to item 1.