JPH0688290B2 - Injection mold and injection molding machine equipped with the mold - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mold suitable for injection-molding a material such as rubber or a thermosetting material, which easily causes burrs, and an injection molding machine equipped with the mold. It is a thing.

[Prior Art] As shown in FIG. 4, a mold clamping device provided in an ordinary injection molding machine has a pair of molds, a fixed mold 3 and a movable mold, on opposite side surfaces of a fixed plate 1 and a movable plate 2. 4 is attached, and tie bar 5
The mold is opened and closed and clamped by moving the movable mold 2 forward and backward using the guide.

In such a mold, when a strong mold clamping force is applied by the mold clamping ram 6 on the back surface of the movable platen, the fixed platen 1 and the movable platen 2 are separated from each other.
As shown in the figure, there is a tendency that the molds are bent, and the molds are distorted from each other, and a gap 7 is formed in the central portion of the patenting surface.

The gap 7 causes burrs, and particularly in the molding of rubber or thermosetting resin, burrs are more likely to occur than in the case of molding a thermoplastic resin due to the flow-curing characteristics and the length of time required for material curing. .

[Problems to be Solved by the Invention] In order to prevent the occurrence of burrs due to the gap between the parting surfaces, the stationary platen has sufficient rigidity and precision to press the parting surface of the mold with a predetermined surface pressure without a gap. Also, it is effective to configure the movable plate and to improve the accuracy of the mold. However, in terms of machine cost, it is extremely expensive, and it is not profitable for the molding industry.Therefore, in most of the actual injection molding processes, burrs are intentionally made large in order to make them easy to remove, and burrs are generated in the post process. It is removed to make a finished product.

With such molding that requires deburring, even if injection molding is performed in a short time, there are negative factors such as time and labor required for post-processing, and the surface from which deburring is not finished beautifully. .

According to the present invention, if the gap on the patenting surface that causes burr can be processed by the mold, the conventional injection molding machine can be used as it is, and the post process is not required, so that the molding cost can be reduced. It was thought from that.

Therefore, a main object of the present invention is to provide a new structure in which even if the mold is distorted due to the mold clamping force, the patenting surface of the portion for molding the molded product maintains close contact without forming a gap. It is to provide a molding die.

[Means for Solving the Problems] The present invention according to the above object utilizes the elastic deformation recovery force of the shape memory alloy to closely contact the parting surface around the cavity formed by the mutual contact of the nests. It is something that I try to contact.

One of the characteristics of shape memory alloys is superelasticity in which a large deformation strain of several percent returns to the original at room temperature. For example, with Ni (nickel) -Ti (titanium) alloy, even if it deforms by 8%, it will completely return to its original state when unloading. It not only recovers the shape, but also produces a large recovery force exceeding 30 kg / mm ² .

One feature of the present invention is a nesting die that comprises a pair of base blocks and nests incorporated in both of the base blocks, and forms a cavity by mutual contact of the nests. One of them is movably provided with respect to the base block, the support of the movable insert is a seat plate, and the seat plate is made of a shape memory alloy having elastic deformation recovery force at room temperature. This is an injection molding die in which the parting surfaces of the nests are in close contact with each other.

Another another feature is a nesting die that comprises a pair of base blocks and nests incorporated in both of the base blocks, and forms a cavity by mutual contact of the nests. One is an injection-molding die in which one part is formed of a shape memory alloy having elastic deformation recovery force at room temperature, and the parting surfaces of the inserts are in close contact with each other by the recovery force of the inserts.

Furthermore, the present invention is also characterized in that the injection molding machine is provided with the above-mentioned injection molding die between the fixed plate and the movable plate.

[Operation] In the injection molding die in which the movable insert is supported by the shape memory alloy,
The mold clamping force partially compresses and deforms the support through the movable insert, and the stress generated at that time pressurizes the movable insert,
Closely contact the other nest and the patent surface.

In addition, in the injection mold in which the insert is made of shape memory alloy,
A stress is generated in the insert due to the compressive deformation of the insert itself due to the mold clamping force, and the stress causes the insert to closely contact the other insert with the patenting surface.

As a result, in any of the injection molds having a structure, no gap is formed on the patent surfaces of the inserts.

The present invention will be described in more detail below with reference to the embodiments shown in FIGS.

[Embodiment] 11 in the drawing is an injection molding die, which includes a fixed mold 15 and a movable mold 16 which are separately attached to the facing surfaces of a fixed plate 13 and a movable plate 14 of a mold clamping device 12 included in the injection molding machine. Consists of.

These molds are of a nesting type in which the nests 19 and 20 are provided inside the base blocks 17 and 18, and the cavity 21 is formed by mutual abutment of the nests.

The insert 19 of the fixed die 15 is housed in the recess 17a of the base block 17 so as to be movable with respect to the parting line.
The insert 20 of 6 is housed and fixed in the recess 18a of the base block 18.

The fixed plate-side insert (hereinafter referred to as a movable insert) 19 integrally has a support leg 19a which is loosely fitted to a through hole 17b formed in the bottom of the recess 17a, and the support leg 19a is in contact with the inserts. It is formed to have a length that slightly protrudes from the outer bottom surface of the block at the time of contact.

The movable mold 16 directly moves the movable plate 14 with the base block 18
The fixed die 15 is attached to the fixed plate 13 via a seat plate 22 that supports the movable insert 19.

The seat plate 22 is made of a shape memory alloy that exhibits elastic deformation recovery force at room temperature, and the mold clamping force and the deformation force and deformation amount generated by being pressed by the supporting leg end surface of the movable insert 19a are the mold clamping force required for molding. , Determined in advance from the injection pressure, etc.

In the fixed mold 15 attached to the fixed platen 13 via this seat plate 22,
Due to the contact between the seat plate 22 and the supporting leg end surface, the movable insert 19 is pushed out from the patten surface of the base block 17 by a predetermined dimension, and the telescopic pad surface is projected.

Therefore, when mold clamping is performed in this state, the movable inserts 19 are pressed by the contact surfaces of the two inserts before the contact surfaces of the base blocks 15 and 16 of both molds contact each other. This pressing force partially acts on the seat plate 22 via the support leg 19a, and partially elastically deforms the seat plate 22 made of a shape memory alloy.

Also, due to the deformation, the movable insert 19a is pushed into the base block so that the mutual facing surfaces of the base blocks come into contact with each other, and the movable insert 19 receives the restoring force of the seat plate 22 while receiving the pressure. As a result, the contact between the nests is kept tight.

Further, at the time of completion of mold clamping, the entire mold is pressed, and the seat plate 22 is elastically deformed entirely by the mold clamping force. It will be pressurized.

In addition, due to the problem of rigidity, even if the fixed block 13 and the movable platen 12 and the base blocks are curved together, no bending deformation occurs between the nests. Since a larger restoring force is applied than that, the contact between the nesting surfaces of the nests, that is, the contact surface around the cavity is kept close, and no gap that causes resin leakage is generated there.

The embodiment shown in FIG. 2 has a movable insert instead of the seat plate 22.
The support of 19 and the movable insert 19 together with the recess of the base block 17
17 shows a case where a seat plate 23 that can be housed in 17a is used.

In such a structure, only the movable insert 19 is subjected to the elastic deformation recovery force of the shape memory alloy, and the inserts are not affected by the curved deformation on the base block side due to the mold clamping force, and the packing surface is closely packed. Touches.

The embodiment shown in FIG. 3 is a case where the movable insert 19 is formed of a shape memory alloy. The movable insert 19 is housed in a recess 17a in the base block with the patenting surface slightly protruding from the patenting surface of the base block 17. Further, because of the fact that it is fixed with a required gap around it, it does not make mechanical movement like the movable insert of the above-mentioned embodiment, but the position of the patenting surface due to elastic deformation of itself,
It is movable with respect to the patenting surface of the base block 17.

In addition, since the movable insert itself is elastically deformed,
21 is formed in the insert 20 on the movable platen 14 side, and the movable insert 19 acts as a closing member for the cavity.

In the above embodiment, the movable insert is provided on the fixed plate side,
In terms of operation, even if the movable insert is provided on the movable plate side, no problem occurs. Therefore, the mounting side of the movable insert is not particularly limited in the present invention.

[Advantages of the Invention] As described above, the present invention forms a mold from a pair of base blocks and a cavity forming insert incorporated in both base blocks, and one insert is made of a shape memory alloy. Since the elastic deformation recovery force is used to closely contact the mating surfaces of the inserts, even if the mold is flexed and deformed due to mold clamping force, the contact of the patent surface around the cavity is kept tight. There is no possibility of resin leakage during dripping or injection.

Moreover, since the purpose can be achieved by adding a seat plate made of a shape memory alloy as a support for the movable insert, or by forming the insert itself by a shape memory alloy, the structure of the insert mold becomes particularly complicated, Since it does not increase the cost and the installation on the injection molding machine is the same as before, it has extremely effective features for injection molding of materials such as rubber and thermosetting that easily generate burrs. .

[Brief description of drawings]

The drawings show an embodiment of an injection molding die according to the present invention. FIG. 1 is a cross-sectional plan view of the first embodiment in a state of being attached to a mold clamping device of an injection molding machine, and FIG. FIG. 3 is a cross-sectional plan view of the embodiment, FIG. 3 is a cross-sectional plan view of the third embodiment, and FIG. 4 is an explanatory view of a conventional injection molding die. 11 …… Injection mold, 12 …… Clamping device 13 …… Fixed plate, 14 …… Movable plate 15 …… Fixed mold, 16 …… Movable mold 17,18 …… Base block 19 …… Moveable insert , 20 …… Nesting 21 …… Cavity 22 …… Seat plate made of shape memory alloy 23 …… Supporting member made of shape memory alloy

Claims (3)

[Claims] 1. A nesting die comprising a pair of base blocks and nests incorporated in both of the base blocks, wherein a cavity is formed by mutual abutment of the nests, wherein one of the nests is a base. It is provided movably with respect to the block, the support of the movable insert is a seat plate, and the seat plate is made of a shape memory alloy having elastic deformation recovery force at room temperature, and the restoring force of the seat plate allows mutual insertion of the inserts. An injection molding die that comes into close contact with the parting surface. 2. A nesting die comprising a pair of base blocks and nests incorporated in both of the base blocks, wherein a cavity is formed by abutment of the nests, one of the nests being at room temperature. An injection-molding die formed of a shape memory alloy having elastic deformation recovery force, and the parting surfaces of the inserts are brought into close contact with each other by the recovery force of the insert. 3. An injection molding machine in which the injection molding die according to claim 1 or 2 is mounted between a fixed platen and a movable platen.