Mold clamping control method for injection molding machine with elbow mold clamping mechanism

Abstract

The present invention is realized by a mold clamping control method of an injection molding machine having an elbow type mold clamping mechanism. The mold clamping control method includes: a low pressure mold clamping process. The position holding control of the head (25) is held at the set holding position; and the compression / pressurizing process is performed to keep the crosshead (25) from the set holding position in the state where the output upper limit value 1 is set in the drive unit The speed and position control for advancing the position toward the set advancing position continues to advance the crosshead (25) with the output of the drive unit maintaining the output upper limit value 1 in at least a part of the compression / pressurization process.

Description

technical field [0001] The present invention relates to a mold clamping control method for an injection molding machine having an elbow type mold clamping mechanism, and more particularly to a mold clamping control method having a low-pressure mold clamping process in which the toggle is bent at the start of injection filling. Perform position hold control to hold the position of the crosshead at the set hold position. Background technique [0002] In a general injection molding method using an injection molding machine equipped with an elbow clamping mechanism, first, the elbow in a bent state is extended by moving (advancing) in the mold closing direction of the crosshead, and the to be guided by the tie rod is extended. The movable plate of the machine moves to the side of the fixed plate, so that the movable mold installed on the movable plate is molded (mold contact) to the fixed mold installed on the fixed plate. In this state, the toggle is not completely stretched (...

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Problems solved by technology

[0028] Therefore, in the compression and pressurization process of the injection compression molding method and the injection pressurization molding method, there is a problem that the compression / pressurization force applied to the molten resin in the mold cavity is not constant, and as the temperature of the molten resin decreases and The volume of the mold cavity is reduced, and the resin pressure is increased

In this way, in the low-pressure mold clamping process and the compression / pressurization process, when the output of the drive unit increases beyond the assumed value, the output will rise to the mechanical upper limit of the drive unit, which may lead to failure. Damage to mold mechanism, injection unit or mold

In addition, if the driving part of the mold clamping device is a servo motor, the servo motor will trip, making it difficult to continue the low-pressure mold clamping process and the compression / pressurizing process, and there may be a reaction due to the forward resistance acting on the driving part. The force causes the movable mold to open, causing damage to the inside of the mold, and even a mold with a sheared edge structure may cause molten resin to be ejected from the mold

[0031] Therefore, including the molding method of the disc molded product of Patent Document 2, there is a compression and pressurization process in which the forward speed of the crosshead is controlled at a constant speed according to the set speed, and the position of the movable mold (crosshead position) is controlled. In the injection compression molding method and the injection pressurization molding method of the low-pressure mold clamping process with position holding control (moving speed ≒ 0), there is a problem that the mold clamping mechanism cannot be protected against an output exceeding assumptions generated by the drive unit of the mold clamping mechanism.

[0032] In addition, even if it is desired to protect the mold clamping mechanism by controlling the injection molding device when the output of the drive unit of the mold clamping mechanism suddenly increases as in the method for molding thin-walled molded products (injection pressure molding method) of Patent Document 1, mold mechanism, injection molding device or mold, but as explained earlier, it is difficult to coordinate the control of the mold clamping mechanism side and the injection molding device side

Moreover, under the premise of failure on the injection molding device side, incorrect setting of the amount of resin to be measured, etc., such coordinated control itself cannot be established, so the protection of the mold clamping mechanism, injection molding device, and mold cannot be expected.

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