JPH0242334B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field to Which the Invention Pertains> The present invention relates to an injection compression molding mold and an injection compression molding method using the same.

<Prior art and its drawbacks> Injection compression molding is a method in which the mold joint surface is opened by a predetermined amount, resin is filled into the mold cavity, and then the mold clamping pressure is increased to close the opening amount. Alternatively, the mold joint surface is initially closed, the joint surface is opened by a predetermined amount by the pressure of the resin filled in the mold cavity, and after filling is completed, the opened joint surface is returned to its original state as the filled resin contracts. There are two ways to close the mold, and in either method, the mold is opened by a predetermined amount of compression when the resin is filled into the mold cavity, and then the clamping force is increased to join the mold in the open state. This method compresses the surface until it closes.

However, in the conventional method, during the compression process after resin filling, the communication between the injection nozzle that supplies resin into the mold cavity and the mold cavity is cut off with a push-off valve, and then compression is performed. The compression process is started by a timeout signal from a timer that operates simultaneously with the start of resin filling, or by an injection completion signal that is sent simultaneously with the completion of filling.

Therefore, regardless of the amount of resin filled into the mold cavity, the injection process is switched to the compression process after a set time has elapsed. Once the compression process is switched to, the resin does not move in and out between the injection nozzle and the mold cavity, and it is not possible to correct whether the resin is filled too much or too little in the mold cavity.

As a result, very strict requirements are placed on metrological accuracy. If the measurement is incorrect for each shot, the amount filled into the mold cavity will also differ, resulting in a difference in the actual compression amount, and the quality of the molded product will vary.

<Objective of the Invention> The present invention eliminates the above-mentioned drawbacks and provides a mold and a method using the mold for obtaining stable injection compression molded products even if the measurement accuracy varies slightly. be.

<Summary of the Invention> To explain the present invention in detail, the situation of the resin filled in the mold cavity in the injection compression mold,
That is, for injection compression molding, a detection device is provided to detect resin pressure, resin temperature, or mold opening amount, and when the detection device reaches a preset filling condition in the mold cavity, the filling process is switched to the compression process. A mold and an injection method using the same.

<Embodiment> Next, an embodiment of the present invention will be described with reference to FIGS. 1 and 2. Reference numeral 11 denotes a mold clamping ram 1 that moves forward and backward by pressure oil from a hydraulic source acting on a mold clamping cylinder 12.
A movable mold fixed to a movable plate 14 integrally attached to a movable mold moves back and forth with respect to a fixed mold 16 attached to a fixed plate 15, and when the molds 11 and 16 are closed during filling with molten resin, the cavity is closed. It cooperates with the plate 17 to form a mold cavity 18. The cavity plate 17 is attached to the movable mold 11 by bolts 19 so that it can move forward and backward by a predetermined amount of compression δ, and when it comes into contact with the mold parting surface A, the predetermined amount of compression δ can be ensured. As such, it is pushed by the piston rod 21 of the mold closing cylinder 20 provided in the movable mold 11 from the back side of the mold parting surface A. 22 is a gate cut cylinder, and its piston rod 23 connects to a spool 18 that communicates with the mold cavity 18 and a resin supply nozzle (not shown) during mold compression after resin filling (the lower half of FIG. 1 is shown).
This is to block the resin path between a. A pressure sensor 24 detects the resin pressure within the mold cavity 18 and is configured to perform detection via a pin 25. 26 is a temperature sensor in mold cavity 1
This is to detect the temperature of the resin in 8. Reference numeral 32 denotes a differential transformer 32a which serves as a mold opening amount detector for detecting the amount of mold opening in contact with the converter 32h. Reference numeral 27 denotes an electromagnetic switching valve for opening and closing the mold, which controls the forward and backward movement of the mold clamping ram 13 by switching the valve. Reference numeral 28 changes the set pressure in the control circuit in proportion to the strength of the voltage acting on the electromagnetic relief valve. Reference numeral 29 denotes a filling state setting device which sets the resin pressure, resin temperature, or mold opening amount detected by the pressure sensor 25, temperature sensor 26, or mold opening amount detector 32 as an electrical signal such as a voltage. 30 is a comparator and the setting position 29
The set value is compared with the value detected by both the sensors 24, 26 or 32, and when the set value and the detected value match, a signal is issued and the electromagnetic relief valve 28
The hydraulic pressure of the mold clamping cylinder 12, which has been the mold clamping pressure for the filling process, is changed to the mold clamping pressure for the compression process. Here, in this embodiment, an electromagnetic relief valve is used to set the mold clamping pressure, but the invention is not limited to this, and there is no problem even if a plurality of relief valves are switched to different set pressures using the coincidence signal. It's self-evident.

31 is a changeover switch for selecting the sensor 24, 26 or 32. In addition, the same changeover switch 31
Both sensors 24, 26 and 32 may be used simultaneously without using the sensor.

<Effects of the Invention> With the above configuration, when resin filling is performed as a pre-process of the compression process, the filling state detection device such as the pressure sensor, temperature sensor, or mold opening amount detection The filling state in the mold cavity is detected, and when a preset filling process completion condition, such as resin pressure or resin temperature, is reached, the next process, the compression process, is started.

Therefore, as originally stated, the drawback of the conventional method of switching from the filling process to the compression process after a preset time has elapsed, regardless of the filling state in the mold cavity, is eliminated.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a mold according to the present invention. FIG. 2 is a diagram showing a control circuit of a mold clamping device using a mold according to the present invention. 11...Moving mold, 16...Fixed mold, 17...
... Cavity plate, 10 ... Mold cavity, 20 ... Mold closing cylinder, 22 ... Gate cut cylinder, 24 ... Pressure sensor, 26 ... Temperature sensor, 28 ... Electromagnetic relief valve, 29 ... Filling state Setting device, 30... Comparator, 32... Mold opening amount detector.

Claims (1)

[Scope of Claims] 1. A mold cavity formed by joining a fixed mold and a movable mold, and maintaining the mold joint surface at a predetermined mold compression amount when filling of resin into the mold cavity is completed. a mold compression amount setting device; a gate cut device that cuts off communication between the mold cavity and the mold gate after the filling of resin into the mold cavity is completed; and resin pressure and temperature in the mold cavity; An injection compression mold consisting of a filling state detection device that detects the filling state of the opening amount and, when a predetermined state is reached, increases the mold clamping pressure and sends a signal to the mold clamping control circuit to compress the filled resin in the mold cavity. . 2. A mold cavity formed by joining a fixed mold and a movable mold, and a mold compression amount setting device that maintains the mold joint surface at a predetermined mold compression amount when filling of resin into the mold cavity is completed. , after the filling of the resin into the mold cavity is completed, a gate cutting device that cuts off the communication between the mold cavity and the mold gate, and a filling state of the resin pressure, temperature, and mold opening amount in the mold cavity; Using a mold consisting of a filling state detection device that increases mold clamping pressure when a predetermined state is reached and sends a signal to a mold clamping control circuit to compress the resin filled in the mold cavity, When filling is completed, the mold joint surface maintained at a predetermined mold compression level is closed, and the filled resin in the mold cavity is pressed.