JPH0539619Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a magnetic field injection molding machine that mixes powdered magnets into thermoplastic resin to form magnetic plastic products of a desired shape.

Recently, many magnetic plastic products have been made by mixing powdered magnets into thermoplastic resin and forming them into desired shapes, such as door sealing magnets that are attached to the opening edges of refrigerators, and self-adhesive buttons for various display purposes. It is starting to be used.

The above powder magnets are usually made of plastic resin at about 90% by weight.
However, when injection molded with a general injection molding machine, the arrangement of the powder magnets in the thermoplastic resin press-fitted into the mold becomes irregular, and the function as a magnet after becoming a magnetic plastic product is insufficient. It becomes something that cannot be fully demonstrated. Therefore, when molding the thermoplastic resin containing the powdered magnet, a magnetic field is applied to the mold to align the polarity of the powdered magnet while the resin injected into the mold is in a molten state, and then solidifies. A magnetic field injection molding machine is used in which the direction of the magnetic field is reversed to demagnetize the material when it is taken out.

[Prior Art] However, as schematically shown in FIG. 6, a conventional magnetic field injection molding machine has a plurality of tie bars 2 (usually four on each side, two on the top and two on the top) fixedly fixed at intervals on a base 1. A coil is attached to one of the pair of fixed plates 3, 4 connected by the tie bars 2, 2, . 7,
8, and by energizing the coils 7 and 8, a magnetic field is formed in the mold sandwiched between the movable plate 6 and the fixed plate 4 through the tie bars 2, 2, . . . .

By the way, according to the above conventional magnetic field forming means, the tie bars 2, 2, . . . used for forming the magnetic field...
In order to maintain the strength of the tie bar, it is made of a material containing carbon, manganese, etc., so it has poor magnetic permeability, so it is necessary to use a material with high magnetic permeability for the tie bars 2, 2... As a result, it is necessary to increase the cross-sectional area in order to maintain the required strength as a tie bar. However, if the tie bars 2, 2... are made thicker, the mold installation dimensions are restricted, which not only makes it difficult to provide strength, but also causes the problem of making the injection molding machine larger than necessary. .

[Purpose of the invention] The present invention has been made with the aim of improving the above-mentioned problems of the prior art. The present invention provides a magnetic field injection molding machine that does not impose restrictions on mold mounting dimensions and does not increase the size of the molding machine by forming a strong magnetic field.

[Main Points of the Invention] The magnetic field injection molding machine of the present invention comprises: a fixed plate A fixed on a base; a fixed plate B fixed on a support seat on the base at a distance from the fixed plate; It has a tie bar that penetrates both fixed plates and is fixed thereto, a movable plate that moves while being supported and guided by the tie bar, and a coil that is attached to the outer periphery of the B fixed plate and the movable plate. In a magnetic field injection molding machine, a magnetic field is formed in the mold through the tie bar only when a mold is attached to both plates, the side surface being in contact with a recess provided in the upper part of the movable plate, and the recess provided in the upper part of the moving plate. a sliding member pushed up by a spring provided on the bottom surface of the B fixing plate; and an arm having one end fixed to the B fixing plate and the other end sliding on the sliding member; It is characterized in that the arm and the support seat are made of a magnetic material with high magnetic permeability.

[Embodiment of the invention] Hereinafter, a description will be given of FIGS. 1 to 4 showing an embodiment of the invention. Components common to those in FIG. 6 will be described with the same reference numerals.

FIG. 1 shows a partially sectional front view of an embodiment of the present invention, in which an A fixing plate 3 is fixedly installed on a base 1, and a B fixing plate is spaced apart from the A fixing plate 3. 21 is fixed on a fixed support seat 9 on the base 1, and a plurality of tie bars 2, 2... are fixed to both of these fixing plates 3, 21 (usually 4 in total, 2 on the top and 2 on each side). ing.
A movable plate 22 is slidably supported on the tie bars 2, 2, . By driving the tightening cylinder 5, a mold (not shown) is clamped between the fixed plate 21 and the movable plate 22.

The coil 7 is attached to the B fixing plate 21,
A mold mounting member 11 made of a non-magnetic material and constituting a mold mounting surface is provided on the outer surface of the coil 7. A coil 8 is attached to the moving plate 22,
A mold mounting member 12 made of a non-magnetic material and constituting a mold mounting surface is provided on the outer surface of the coil 8.

The fixed plate 21 and the movable plate 2
2 are magnetically connected to each other by arms 13, 13 made of a material with high magnetic permeability. Arm 1 serves as a magnetic connection means by these arms 13, 13.
One end of the arm 3, 13 is fixed to the upper surface of the B fixed plate 21, and the other end of the arm 13, 13 is fixed to the upper surface of the B fixed plate 21.
Place it on the top surface of 2. On the other hand, a groove 23 is formed in the upper surface of the moving plate 22, as shown in FIGS. 3 and 4, and a convex sliding member 24 made of a material with high magnetic permeability is inserted into the groove 23. Sliding member 24
is in contact with both sides of the groove 23 on both sides of the wide part, and the upper surface is in contact with the bottom of the groove 23 by the spring 25.
It is in contact with the lower surface of 3 and 13. Therefore, even when the moving plate 22 moves, a loop is formed between the moving plate 22, the sliding member 24, the arms 13, 13, and the B fixed plate 21 between the moving plate 22 and the B fixed plate 21.
1 are magnetically connected.

Further, the support seat 9 is also made of a magnetic material. The lower part of the moving plate 22 is slidably moved on this support seat 9. In the figure 1
6 and 16 are dowel pins that push out the product from inside the mold;
17 is an injection port for supplying molten resin into the mold.

Since the present invention has the above configuration, the fixed plate 2
A mold is inserted between the movable plate 22 and the movable plate 22, and the mold is clamped by the movable plate 22 by driving the mold clamping cylinder 5. After that, the molten resin containing the powder magnet is poured into the mold from the injection port 17. is press-fitted by an appropriate supply means. At the same time, when the coils 7 and 8 are energized, a magnetic field is formed through the arms 13 and 13 connecting the fixed plate 21 and the movable plate 22 and the support seat 9 made of magnetic material, and this magnetic field passes through the mold. This creates a magnetic field that aligns the powder magnets in the molten resin in the mold in a certain direction.
It is magnetized.

After the molten resin has solidified, the moving plate 22 is returned and the product is protruded by the dowel pin 16 and collected. As a result, a magnetic plastic product can be obtained in which the polarity of the powder magnets is aligned. In the above action, the magnetic field is
Since the magnetic field is formed through the support seats 9, 9, a strong magnetic field is generated and the alignment of the powder magnets can be further improved.

FIG. 5 shows another embodiment of the present invention. In this example, one end of the arms 13A, 13A made of a material with high magnetic permeability is connected to the B fixing plate 2.
1, and fix the other end to the A fixing plate 3.
It is fixed to the top surface of. Note that a groove 23 is formed on the upper surface of the moving plate 22, and the groove 23
The sliding member made of a material with high magnetic permeability is inserted therein to contact the arms 13A, 13A, as in the first embodiment described above. Also arm 13A,
The other end of 13A may not be fixed to the upper surface of the A-fixed die plate 3, but a piece may be attached to the upper surface of the tie bar 2 in a shape that straddles the tie bar 2, and it may be fixed to this piece.

[Effects of the invention] As explained above, the magnetic field injection molding machine of the invention magnetically connects the stationary plate and the movable plate with a magnetic member with high magnetic permeability, and the support seats of the movable plate and the stationary plate have a high permeability. The magnetic field is formed between the fixed plate and the movable plate through each of the above-mentioned magnetic members, which creates a stronger magnetic field than the conventional tie bars that create a magnetic field. can be formed. In addition, since the tie bars are not actively used to form a magnetic field, the tie bars can be made of the same strong material as before, so there is no need to make the tie bars thicker, and the injection molding machine can be made larger. There are various excellent effects such as not only being free of heat, but also not restricting the mounting dimensions of the mold.

[Brief explanation of the drawing]

Fig. 1 is a partially sectional front view showing an embodiment of a magnetic field injection molding machine according to the present invention, Fig. 2 is a sectional view taken along the line 2-2 in Fig. 1, and Fig. 3 is a 3-3 sectional view in Fig. 1. 4 is a sectional view taken along line 4-4 in FIG. 3, FIG. 5 is a partially sectional front view of another embodiment of the present invention, and FIG. 6 is a schematic illustration of a conventional example. It is a diagram. 1... Base, 2... Tie bar, 3... A fixing plate, 7, 8... Coil, 9... Support seat, 1
3, 13, 13A, 13A...Arm, 21...
B fixed plate, 22... movable plate, 23...
...Groove, 24...Sliding member, 25...Spring.

Claims (1)

[Claims for Utility Model Registration] A fixing plate fixed on the base, a fixing plate B fixed to the support seat on the base at a distance from the fixing plate, and penetrating both the fixing plates. and a tie bar fixed to the tie bar, a movable plate that moves supported and guided by the tie bar, and a coil attached to the outer periphery of the B fixed plate and the movable plate. In a magnetic field injection molding machine in which a magnetic field is formed in the mold through the tie bar only when the mold is attached, a magnetic field is provided in the mold, the side surface of which is in contact with the recess provided at the top of the moving plate, and the magnetic field provided at the bottom of the recess. It has a sliding member that is pushed up by a spring, and an arm that has one end fixed to the B fixing plate and the other end that slides on the sliding member, and the sliding member, the arm, and the support seat. A magnetic field injection molding machine characterized by using a magnetic material with high magnetic permeability.