JPH0525656B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a plastic injection compression molding device and a molding method thereof, and particularly to a device for supplying and pressurizing molten resin to a mold, and a molding method thereof. This invention relates to a plastic injection compression molding apparatus and a molding method thereof.

[Prior Art] Conventionally, in injection molding, molten resin is supplied into a closed mold space (cavity) through a gate, which causes orientation of the resin, and high pressure near the gate leaves strong residual strain. For this reason, warpage and twisting are likely to occur in the molded product, and physical properties in the vicinity of the gate and the like are deteriorated. As a solution to this problem, there is an injection compression (or press) molding method in which an appropriate amount of molten resin is supplied to an open mold, and then the mold is closed and compression molded. The stability of the molded product may be impaired due to dents (sink marks) near the gate or lack of weight. To prevent this, when compressing the mold, (1) compress after gate sealing (solidifying the resin at the gate).

(2) Close the supply port. (Japanese Patent Publication No. 61-22917) (3) Control compression pressure. (Japanese Patent Publication No. 61-83016) There are other methods.

[Problems to be Solved by the Invention] However, according to the above-mentioned conventional injection compression molding method, (1) it is necessary to wait for compression until the time for gate sealing (resin solidification at the gate), and it is necessary to take appropriate compression timing; Hateful. Furthermore, if the gate is made thinner in order to speed up gate sealing, resin injection may take longer and the appropriate size may not be obtained.

(2) When closing the supply port, backflow occurs if the timing of compression is too fast, and it is difficult to close the supply port completely and quickly, making it difficult to time the closure of the supply port and compression.(3) Compression pressure The method for controlling backflow requires many conditions and restrictions to prevent backflow, making it difficult to set.

Also, in cases (2) and (3), if there is a spool runner,
It has drawbacks that make it particularly difficult.

The present invention focuses on the above-mentioned conventional problems and provides an injection compression molding apparatus and method for molding molded products with stable quality and high productivity without dents in the vicinity of the resin supply section and with good appearance and dimensional accuracy. It is an object.

[Means for Solving the Problems] In order to achieve the above object, the injection compression molding apparatus of the first aspect of the present invention has a compression molding apparatus such as a press that opens and closes the mold and a molten resin between the mold. In an injection compression molding device having an injection machine to be supplied, there is a mechanical fixing mechanism that mechanically fixes the mold at an open position of a predetermined mold, and a mechanism that opens a gate at an open position of the predetermined mold to allow the mold to enter the cavity. A gate opening/closing mechanism that injects the resin, closes the gate after the injection is completed, and compresses the resin, and a resin passageway that opens the gate when or after the compression is completed to resume resin injection, and closes the gate again after injecting the appropriate amount to stop injection filling. It consists of a variable mechanism and more. In the injection compression molding method of the second aspect of the invention, a molten resin is supplied between molds, compressed, cooled, and molded, and the resin is supplied again after compression. Further, for this purpose, in the third invention, the gate of the resin supply port is made openable and closable, and the gate is closed from the completion of resin supply to the completion of compression, and is opened when the resin is resupplied. Furthermore, the fourth invention is characterized in that the area of the gate of the resin supply port or the supply passage is variable, and when the resin is resupplied, the resin is supplied from a smaller area than when the resin is supplied.

[Operation] According to the above configuration, the gate opening/closing mechanism opens the gate at a predetermined open position of the mold, injects the resin, and closes the gate after the injection is completed. The resin is compressed at or before the completion of injection, but until the compression is complete, the gate is closed by the gate opening/closing mechanism, so the amount of escape due to backflow is small, and only the area in the vicinity of the injection port connected to the gate flows back. At or after the completion of compression, the gate is opened to resume resin injection, and after an appropriate amount has been injected, the gate is closed again to stop injection.
Therefore, it is possible to supply the escape amount during compression,
A molded product without dents and with good appearance and dimensional accuracy can be obtained. In addition, the resin passage variable mechanism allows the passage to be made narrower and more variable when resupplying resin, so by selecting the size of the passage area, the pressure propagation range can be adjusted, and the injection pressure is applied only in the vicinity of the area where resin backflow occurs. This allows the resin to be resupplied without residual strain.

[Example] Hereinafter, examples of the injection compression molding apparatus and method according to the present invention will be described in detail with reference to the drawings. FIG. 1 is an overall configuration diagram of an embodiment of the present invention, and FIG. 2 is a flowchart of the embodiment. In FIG. 1, a lift cylinder 4 is fixed to a frame 2 of a compression molding machine 1 to slidably move a movable die plate 3 using hydraulic pressure from a pump (not shown). However, fixed molds 7 are respectively attached to the table 6. An injection port 8 is formed in the fixed mold 7, and through this injection port 8, molten resin 9 injected from an injection part 40 in the table 6 is injected and filled into a cavity 10 formed in both molds 5 and 7. It is becoming more and more common. Movable die plate 3
is mechanically fixed by a mechanical fixing mechanism 20 at a position where a predetermined distance A is established between both molds 5 and 7.
The mechanical fixing mechanism 20 includes a compression cylinder 21 that compresses the resin injected and filled into the cavity 10;
A link 22 that supports the compression cylinder 21, a lock cylinder 23 that tilts the link 22, the link 22 and the lock cylinder 23 are fixed to the cylinder frame 24 via pins 25 and 26, and the cylinder frame 24 is fixed to the thickness of the mold. A pair of rods 28 and a high adjuster 27 are provided to move the molds 5 and 7 by a predetermined distance A or the like (in the X direction). The injection section 40 includes an injection mechanism 50 and a gate opening/closing mechanism 60.
and a resin passage variable mechanism 70. The injection mechanism 50 includes a screw 51, a screw rotation motor 52, and an injection cylinder 53, and injects resin by sliding the injection cylinder 53. A gate part opening/closing mechanism 60 and a resin passage variable mechanism 70 are provided at the gate 54 between the fixed mold 7 and the injection mechanism 50, and a servo motor 62 is operated based on a command from a controller 61 to close the gate part. Opening/closing mechanism 6
The valve 63 of the valve 63 of the variable resin passage mechanism 70 is opened and closed, and the relative position of the passage 71 opened in the valve 63 of the variable resin passage mechanism 70 and the gate 54 is varied to determine the size of the area.

The operation of the above configuration will now be described with reference to FIGS. 2 and 3. In FIG. 2, when performing injection compression molding, hydraulic pressure is applied to the lift cylinder 4 from a pump (not shown) to move the movable die plate 3 to a position where the distance between the two molds 5 and 7 is a predetermined distance A (step 81). . Although the position detection at this time is not shown, it may be measured by the lift cylinder 4, the movable die plate 3, and the movable mold 5. When the movable die plate 3 comes to the predetermined position, hydraulic pressure is applied to the lock cylinder 23 of the mechanical fixing mechanism 20, which is adjusted to a predetermined distance A by the high adjuster 27, and the mechanical fixing mechanism 20 is moved from the position indicated by the dotted line A. The movable die plate 3 is mechanically fixed by tilting it to the position indicated by the solid line B (step 82). Mechanical fixation is detected by a position sensor (not shown) provided on the pins 25, 26, etc., and the servo motor 62 is operated based on a command from the controller 61 to open the valve 63 of the gate opening/closing mechanism 60. (step
83). Next, the oil pressure and oil amount of the injection cylinder 53 are controlled so that the initially set injection speed and injection pressure are achieved, and the screw 51 is slid to inject and fill the resin into the cavity 10 (step 84). At this time, the movable mold 5 tries to open due to the resin pressure inside the cavity 10, but since it is mechanically fixed via the movable die plate 3, the predetermined distance between the two molds 5 and 7 that was initially set is maintained. A can be maintained. Whether or not a predetermined amount of resin has been injected is determined by detecting the screw position, etc., as in the prior art. When a predetermined amount of resin has been injected, the servo motor 62 is operated based on a command from the control 61 to close the valve 63 of the gate opening/closing mechanism 60 (step 85). Next, in order to compress the resin in the cavity 10, hydraulic pressure is applied to the compression cylinder 21, and the movable mold 5 is slid toward the fixed mold 7 via the movable die plate 3 to perform compression molding (step 86). After sliding to a predetermined position and a predetermined time has elapsed (step 87), the servo motor 62 is activated based on a command from the controller 61 to adjust the passage 71 of the variable resin passage mechanism 70 to the originally set area. Open by a predetermined amount (step 88). The opening degree of the passage at this time is smaller than that during injection in step 84, 3 to 60%.
is good, preferably 5 to 30%. When the passage 71 of the variable resin passage mechanism 70 is opened, it should be placed very close to the injection port connected to the gate where resin backflow occurred, as shown in Figure 3, so that the pressure propagation range does not reach other filled areas. A predetermined amount of resin is injected again to fill the dent (step 89). When a predetermined amount of resin is filled, the resin passage variable mechanism 70 is closed again (step 90) and maintained until the resin is cooled. After cooling, hydraulic pressure is applied to the compression cylinder 21 and lock cylinder 23 to release the mechanical fixing mechanism 20.
The lift cylinder 4 is moved to open the mold and take out the product.

In the above example, when the predetermined amount of resin is filled in step 84, the valve 63 of the gate opening/closing mechanism 60
However, the gate opening/closing mechanism 60 may be closed during filling of a predetermined amount, and similarly, after closing the valve 63 of the gate opening/closing mechanism 60 in steps 85 and 86, the resin is compression molded. However, the valve 63 of the gate opening/closing mechanism 60 may be closed while compression molding the resin. Furthermore, although the passage 71 of the variable resin passage mechanism 70 is opened after a predetermined time has elapsed in step 87, it may be opened by detecting the pressure inside the cavity 10. Further, the mechanical fixing mechanism is not limited to the above embodiment, and links that move in parallel may be used.

[Effects of the Invention] As explained above, according to the present invention, a mechanical fixing mechanism for mechanically fixing a mold in an open position of a predetermined mold to an injection compression molding apparatus, and There is a gate opening/closing mechanism that opens the gate at the desired position and injects the resin, closes the gate after the injection is completed, and compresses the resin.The gate opens and closes the gate when the compression is completed or after that, resumes resin injection, and closes the gate again after injecting the appropriate amount. Since a variable resin passage mechanism is provided to stop filling, it is possible to supply the escape amount during compression, and the variable resin passage mechanism allows the passage to be made narrower and variable when resupplying resin, so the size of the area of the passage can be reduced. By selection, the pressure propagation range can be adjusted, and injection pressure can be applied only to the vicinity of the range where resin backflow occurs. Therefore, there is no residual strain, no dents near the resin supply part, and the appearance is
It is possible to provide an injection compression molding apparatus and method for molding molded products with good dimensional accuracy with stable quality and high productivity.

[Brief explanation of the drawing]

FIG. 1a is an overall configuration diagram of one embodiment of the present invention. FIG. 1b is a partially enlarged view of FIG. 1. FIG. 2 is a flow chart of one embodiment of the present invention. FIG. 3 is an explanatory diagram of the resin near the injection port of the present invention. 1... Compression molding machine, 3... Movable die plate,
4... Lift cylinder, 5... Moving mold, 6...
Fixed mold, 7... Inlet, 10... Cavity,
20... Mechanical fixing mechanism, 21... Compression cylinder, 22... Link, 23... Lock cylinder,
24...Cylinder frame, 27...Height adjuster, 50...Injection mechanism, 54...Gate, 6
0... Gate opening/closing mechanism, 61... Controller, 70... Resin passage variable mechanism.

Claims (1)

[Claims] 1. In an injection compression molding device that has a compression molding device such as a press that opens and closes the mold and an injection machine that supplies molten resin between the molds, the mold is opened at a predetermined position where the mold is opened. A mechanical fixing mechanism that mechanically fixes the mold, a gate opening/closing mechanism that opens the gate at a predetermined open position of the mold to inject resin into the cavity, closes the gate after injection is completed, and compresses the resin, and a gate opening/closing mechanism that compresses the resin when the compression is completed. Alternatively, an injection compression molding device comprising a variable resin passage mechanism that subsequently opens a gate to resume injection of resin, and after injecting an appropriate amount, closes the gate again to stop injection filling. 2. In an injection compression molding method in which molten resin is supplied between molds, compressed, cooled and molded, the injection compression molding is characterized in that after compressing the resin in the cavity, the insufficient resin is resupplied by opening a gate. Method. 3. The injection compression molding method according to claim 2, wherein the gate of the resin supply port is openable and closable, the gate is closed from the completion of resin supply to the completion of compression, and the gate is opened when the resin is resupplied. 4. The injection compression molding method according to claim 2, wherein the area of the gate of the resin supply port or the supply passage is variable, and when the resin is resupplied, the resin is supplied from a smaller area than when the resin is supplied.