JPS63307923A - Sensing method for clogging of resin flow channel of injection molding machine - Google Patents

Abstract

PURPOSE:To uncover clogging of a resin flow channel at an early stage by providing a sensor to sense the molten resin pressure on a cavity section of a mold. CONSTITUTION:Molten resin 31 in a barrel 15 is injected into a cavity 13 by moving a screw 17 forward when a fixed mold 11 and a movable mold 12 are clamped with, and the barrel 15 is moved forward to switch over an electromagnetic switching valve 24 from the neutral position to a chamber (b). At that time, a timer 29 is in and the time is out, and a comparison device 26 is actuated. The pressure of molten resin injected into the cavity 13 is sensed out by a sensor 25 and transferred to the comparison device 26, being compared with the reference pressure stored in a control device 27, and in case the sensed value is smaller than the reference pressure, an alarm is issued as an outside output 28 of the comparison device 26. The clogging of the resin flow channel is discovered immediately and a counter measure is taken.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a method for detecting resin wave path clogging in an injection molding machine.

[Prior art] Conventional injection molding machines do not detect when the resin flow path is clogged and insufficient molten resin is injected into the mold cavity, so the molten resin in the barrel is exposed to a pressure higher than the injection pressure. If held, the injection time will end and the machine will continue operating without producing a high quality molded part. Therefore, the machine continues to operate without detecting clogging of the resin flow path, reducing productivity. The high pressure of molten resin inside the barrel can cause problems with the injection molding machine, and if the nozzle becomes clogged, a large force is applied to it, damaging it, or if the spool runner of the mold gets clogged. There were cases where the mold was damaged.

[Object of the invention] The present invention eliminates such drawbacks, and its object is to:
It is an object of the present invention to provide a method for detecting clogging of a resin passage in an injection molding machine, which detects clogging of the resin passage at an early stage, extends the life of the injection molding machine, a nozzle, or a mold, and increases productivity.

[Summary of the Invention] The method for detecting clogging of a resin flow path in an injection molding machine according to the present invention includes providing a sensor for detecting molten resin pressure in a cavity of a mold, and starting a timer at the same time as injection of molten resin into the cavity is started. The feature is that at the time of timeout, the reference pressure stored in the control device is compared with the detected value of the sensor, and if the detected value is lower, an alarm is issued.

[Embodiment of the Invention] A diagram showing an embodiment of the present invention will be described below. The fixed mold 11 is fixed to a fixed gouging plate (not shown), and the movable mold 12 is fixed to a moving gouging plate (not shown), and a cavity 13 is formed in the facing surfaces of both molds 11 and 12. Nozzle 14 in contact with fixed mold 11 during injection
A screw 17 is inserted into the barrel 15, which is provided with a heater 16 for heating the resin inside and is capable of rotation and axial movement. Note that 18 is a hopper in which powdered resin 19 is stored.

The screw 17 is rotated by a hydraulic motor 21 driven by pressure oil from a hydraulic source 20 via a piston 23 of a cylinder 22, while axial movement is controlled by an electromagnetic switching valve 24 to control forward/backward movement and stop of the piston 23 of the cylinder 22. This is done by 25 is a sensor that detects the pressure of the molten resin injected into the cavity 13, and this detected value is sent to a comparator 26, where it is compared with the reference pressure stored in the control device 27, and if the detected value is less than the reference value. In this case, the signal is output to the external output terminal 28 of the comparator 26 and an alarm is generated. Further, a timer 29 is connected to the B chamber side of the electromagnetic switching valve 24, and when the electromagnetic switching valve 24 switches to the B chamber, the timer 29 enters, and when the injection end time is set as the timeout time, the above-mentioned comparator is activated. 26 is activated.

In such a configuration, the fixed mold 11 and the movable mold 12
After the mold is clamped and the barrel 15 moves forward (moves to the left) and touches the nozzle, when the electromagnetic switching valve 24 is switched from the neutral position shown in the figure to chamber b, the molten resin 31 in the barrel 15
is injected into the cavity 13 by the advancement of the screw 17. The timer 29 is activated at the same time as the electromagnetic switching valve 24 is switched, and when the timer 29 times out, the comparator 26 is activated, so the pressure of the molten resin injected into the cavity 13 is detected by the sensor 25 and the comparator 26
Here, the detected value is compared with the reference pressure stored in the control device 27, and if the detected value is equal to or greater than the reference pressure, the work continues, but if it is smaller, the output is sent to the external output 28 of the comparator 26. An alarm is issued.

[Effects of the Invention] As explained above, the method for detecting clogging of the resin flow path of an injection molding machine according to the present invention is such that when injection is performed with the resin flow path clogged, the molten resin pressure in the cavity is lower than the reference pressure. An alarm is generated by the comparator. Therefore, clogging of the resin flow path is immediately discovered and countermeasures are taken, so there is no reduction in productivity, and there is no possibility that it will have an adverse effect on the injection molding machine. It is.

11... Fixed mold, 12... Movable mold, 13...
Cavity, 25... Sensor, 26... Comparator, 2
7...Control device, 28...Alarm, 29...Timer.

Claims (1)

[Claims] A sensor for detecting the pressure of the molten resin is provided in the cavity of the mold, and a timer is started at the same time as injection of the molten resin into the cavity is started, and when the timeout elapses, the reference pressure stored in the control device and the detected value of the sensor are set. A method for detecting clogging in a resin flow path of an injection molding machine, in which the detected value is compared and an alarm is issued when the detected value is lower.