JPH0596593A - Method and device for controlling quantity of resin in press molding machine - Google Patents

Abstract

PURPOSE:To inject a fixed quantity of a molten resin into a cavity from injection gates respectively even when injection speed is changed by detecting the position of the screw of an injector, opening and closing each injection gate on the basis of the position of the screw and controlling the quantity of the molten resin injected into the cavity. CONSTITUTION:A mold 10 is mold-clamped and a molten resin is molded after the molten resin is injected into the cavities 24, 25 of the mold 10 under a half-opened state through a plurality of opening-closing-able injection gates 16, l8 from an injector 26 or during injection. The position of the screw 28 of the injector 26 is detected, and each injection gate 16, 18 is opened and closed on the basis of the position of the screw 28, thus controlling the quantities of the molten resin injected into the cavities 24, 25. Accordingly, the opening- closing timing of each injection gate 16, 18 is controlled by the position of the screw 28 in the injector 26, thus allowing the positive injection of a fixed quantity of the molten resin from each injection gate 16, 18 even when injection speed is varied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin amount control method and apparatus for a press molding machine.

[0002]

2. Description of the Related Art As a conventional resin amount control device for a press molding machine, for example, a mold having a plurality of injection gates that can be opened and closed by valves is used, and the opening / closing timing of the injection gates is controlled by a signal from a timer. There is something like this. The opening and closing timing of each injection gate is set in advance by a timer. When the set time of the timer is reached, each injection gate is opened or closed, and the amount of molten resin injected from each injection gate into the cavity is controlled.

[0003]

However, in the above-described conventional resin amount control method and apparatus for a press molding machine, the opening / closing timing of each injection gate is controlled by a timer, so that there are the following problems. That is, when the injection speed of the injection device that is the injection source is changed, the injection time is changed. Therefore, the amount of resin injected from each injection gate into the cavity changes, the injection gate is closed before a predetermined amount of resin is injected into the cavity, or more than a predetermined amount of molten resin is injected into the cavity. There is. The work of resetting the timer according to the change of the injection speed is very troublesome. The present invention is intended to solve such a problem.

[0004]

The present invention solves the above problems by controlling the opening and closing of the injection gate based on the position of the screw. That is, the method for controlling the resin amount of the press molding machine of the present invention is such that after the molten resin is injected from the injection device through the plurality of openable / closable injection gates into the cavity of the mold in the half-open state, the mold is clamped. The position of the screw of the injection device,
Based on this, the amount of molten resin injected into the cavity is controlled by opening and closing each injection gate. Further, the resin amount control device of the press molding machine of the present invention is such that the molten resin is injected from the injection device capable of injecting the molten resin by the axial movement of the screw and the cavity of the mold half opened through the injection gate which can be opened and closed by the valve. In the case where molding is performed after injection into or during injection, the position detector that detects the axial position of the screw and the opening / closing timing of each injection gate are set to the axial position of the screw. Based on the open / close position setter set based on the above, a comparator that compares the detected value detected by the position detector with the set value preset by the open / close position setter, and when the detected value and the set value match A valve drive device that drives each valve according to a signal output from the comparator.

[0005]

[Function] Since the opening / closing timing of each injection gate is controlled by the position of the screw in the injection device, even if the injection speed is changed, a certain amount of molten resin must be injected into the cavity from each injection gate. You can

[0006]

EXAMPLE FIG. 1 shows an example of the present invention. The mold 10 is composed of a lower mold 12 and an upper mold 14. Lower mold 1
Two injection gates 16 and 18 are provided in 2. A valve 20 is provided at each of the injection gates 16 and 18.
And 22 are provided. Valve drives 36 and 38 capable of driving the valves 20 and 22 are connected to the valves 20 and 22, respectively. These allow valves 20 and 22
Is moved in the axial direction to open and close the injection gates 16 and 18. An injection device 26 for injecting the molten resin into the cavities 24 and 25 is connected to the lower mold 12. The injection device 26 is provided with a screw 28, and the molten resin is injected by moving the screw 28 in the axial direction. From the injection gate 16 to the cavity 24, from the injection gate 18 to the cavity 25,
Molten resin is injected into each. A position detector 30 for detecting the position of the screw 28 is connected to the screw 28. The position detector 30 is connected to the comparator 32.
The comparator 32 is also connected to an opening / closing position setter 34 that sets the opening / closing timing of the injection gates 16 and 18 based on the axial position of the injection device 26. In the comparator 32,
The detection value detected by the position detector 30 is compared with the set value set by the opening / closing position setter 34, and when the detected value and the set value match, the valve drive devices 36 and 3
The signal is output to 8. As a result, the valve drive device 3
6 and 38 drive valves 20 and 22, respectively,
The injection gates 16 and 18 are opened and closed.

Next, the operation of this embodiment will be described.
The open position P0 and the closed position P1 of the injection gate 16 and the set values of the open position P3 and the closed position P4 of the injection gate 18 are set in the open / close position setter 34 to move from the injection gates 16 and 18 to the cavities 24 and 25, respectively. Set the amount of molten resin injected. The mold 10 is brought into a half-opened state as shown, and the screw 28 is moved in the axial direction (left direction in the drawing) to start the injection of the molten resin from the injection device 26 into the lower mold 12. At this time, the injection gates 16 and 18 are closed. The moving position of the screw 28 is detected by the position detector 30 and input to the comparator 32. Screw 28
When the injection gate 16 moves to the open position P0, the detection value input to the comparator 32 and the open position P0 match, so a signal is output from the comparator 32 to the valve drive device 36, and the valve 20 opens. Then, the injection gate 16 is opened. As a result, the molten resin is injected from the injection gate 16 into the cavity 24. When the screw 28 further moves to the closed position P1 of the injection gate 16, the comparator 3
Since the detection value input to 2 and the closed position P1 match,
A signal is output from the comparator 32 to the valve drive device 36,
The valve 20 is closed and the injection gate 16 is closed. Since the closed position P1 of the injection gate 16 and the open position P2 of the injection gate 18 are set to the same position, the detected value and the open position P2 of the injection gate 18 coincide with each other at the same time as the above operation. Therefore, a signal is output from the comparator 32 to the valve driving device 38, the valve 22 is opened, and the injection gate 18 is opened.
Is open. That is, at the same time as the injection gate 16 is closed, the injection gate 18 is opened. As a result, the injection of the molten resin from the injection gate 16 into the cavity 24 is completed, and at the same time, the injection of the molten resin from the injection gate 18 into the cavity 25 is started. Screw 2
When 8 further moves to the closed position P3 of the injection gate 18, the detection value input to the comparator 32 and the closed position P3 match, so that a signal for closing the gate from the comparator 32 to the valve drive device 38. Output, the valve 22 is closed, and the injection gate 18 is closed. This completes the supply of the molten resin to the cavity 25.

In addition to the above-mentioned opening / closing control of the injection gates 16 and 18, by combining general injection speed control and multistage pressure control, the injection speed and injection of the molten resin from the injection gates 16 and 18 into the cavities 24 and 25. The pressure can be controlled as desired. After the completion of the injection of the molten resin or during the injection, a mold clamping device (not shown) is operated to perform the mold clamping to complete the molding.

[0009]

According to the present invention, since the opening / closing timing of the injection gate is controlled by the position of the screw of the injection device, a predetermined amount of molten resin is injected from the injection gate into the cavity even if the injection speed is changed. can do.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

[Explanation of symbols]

 10 Mold 16, 18 Injection Gate 20, 22 Valve 24, 25 Cavity 26 Injection Device 28 Screw 30 Position Detector 32 Comparator 34 Open / Close Positioner 36, 38 Valve Drive Device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B29C 45/70 7365-4F

Claims (2)

[Claims] 1. A resin for a press molding machine, which performs molding after injecting a molten resin from an injection device through a plurality of openable / closable injection gates into a cavity of a half-open mold, or by clamping the mold during the injection. In the quantity control method, the position of the screw of the injection device is detected, and based on this, the amount of molten resin injected into the cavity is controlled by opening and closing each injection gate. Method. 2. The molten resin is semi-opened from an injection device (26) capable of injecting the molten resin by axial movement of a screw (28) through an injection gate (16, 18) which can be opened and closed by a valve (20, 22). In a resin amount control device of a press molding machine for performing molding by clamping the mold (10) after or during injection into the cavity (24, 25) of the mold (10) in the state, the screw (28) A position detector (30) for detecting the axial position of the screw, and an opening / closing position setter (34) for setting the opening / closing timing of each injection gate (16, 18) based on the axial position of the screw (28). A comparator (32) for comparing the detection value detected by the position detector (30) with the setting value preset by the opening / closing position setting device (34), and when the detection value and the setting value match. Comparison Each by a signal output from the (32) valve (20, 2
And a valve drive device (36, 38) for driving 2), and a resin amount control device for a press molding machine.