JPS6330221A - Auto-purge method of injection device - Google Patents

Abstract

PURPOSE:To discharge effectively resin which is apt to stay and stick, by repeating a plurality of actions wherein a high-speed and low-speed regular rotations of a screw are repeated and reciprocations of the screw are performed respectively a plurality of times at an advance end. CONSTITUTION:At the time of purge, a high-speed rotation and low-speed rotation are repeated a plurality of times at predetermined time intervals by advancing a screw 2 to an advance end. With this construction, resin stuck to a screw face of the screw 2 is sent out by peeling off by inertia force. When the action is completed,the screw 2 is reciprocated a plurality of times from the advance end to the backward movement end. With this construction, the resin stuck to a wall surface of a hopper 1 is squeezed by the screw 2, stripped off and sent out. The remaining resin can be discharged reliably through a nozzle 4 by repeating the two actions a plurality of times.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an auto-purging method for injection devices of extruders and injection molding machines.

Conventional technology As an injection device for an extruder or an injection molding machine, a screw is installed in a cylindrical holder so that it can rotate and reciprocate between forward and backward ends, and the molten resin is moved around the screw in a rotary and reciprocating manner. It is known that when the holder is moved, it is ejected from a nozzle provided at the tip of the holder.

In such an injection device, when replacing the material to be injected, it is necessary to perform a so-called auto purge to discharge the material remaining in the holder.

Conventionally, the screw is rotated and the screw is reciprocated several times in succession to discharge the material remaining in the holder from the nozzle.

Problems to be Solved by the Invention As mentioned above, it is difficult to effectively discharge resin that tends to stagnate and stick even if the operation is carried out. It is desired to develop a purging method.

Means and operation for solving the problem An operation of repeating high-speed forward rotation and low-speed forward rotation of the screw at the forward end multiple times, and an operation of reciprocating the screw multiple times between the forward end and the reverse end. By repeating this process multiple times, the resin adhering to the threaded surface of the screw and the inner wall of the holder can be peeled off and discharged.

Embodiment FIG. 1 is an explanatory diagram of an injection device, in which a screw 2 is provided in a cylindrical holder 1 so as to be rotatable and reciprocating between a forward end and a backward end. Hopper 3
is provided, and a nozzle 4 is provided at the tip,
The tip 5 of the screw 2 has a conical shape.

The injection cylinder 6 includes a cylinder tube 7 integrated with the holder 1, and a piston 9 having a hollow rod 8 is inserted into the cylinder tube 7 to form an expansion chamber 10 and a contraction chamber 11. A rotary shaft 12 is fitted into the hollow portion so as to be rotatable and not move in the longitudinal direction, and an output shaft 14 of a motor 13 is connected to one end of the rotary shaft 12. The screw 2 is connected to the other end.

The discharge passage 16 of the pump 15 is connected to a first operating valve 17 and a first operating valve 17.
The first passage I8 is connected to the reduction chamber 11.
The second passage 19 is connected to the third and fourth passages 21 and 22 and the drain passage 23 by a second operation valve 20, and the third passage 21 is connected to the extension chamber 10, and the fourth passage 19 is connected to the extension chamber 10, The line 22 is connected to the motor 13, and the drain line 23 is connected to the tank 25 via a back pressure regulating valve 24.

Therefore, the first operating valve I7 is moved from the neutral position N to the retracted position I.
Then, the pressure oil discharged from the pump 15 is supplied to the contraction chamber 11, the piston 9 contracts, and the screw 2 moves backward, and when the position is extended, the pressure oil discharged from the pump 15 is supplied to the second passage 19, and the screw 2 moves backward. When the two-operation valve 20 is moved from the neutral position N to the extended position ■, the pressure oil discharged from the pump 15 is supplied to the extension chamber 10, the piston 9 is extended, and the screw 2 moves forward. As a result, the screw 2 rotates at high speed in the molten resin delivery direction. Note that when the second operation valve 20 is set to the neutral position N, pressure oil with a pressure compensated by the back pressure regulating valve 24 is supplied to the extension chamber 10 and the motor 13, the motor 13 rotates forward at low speed, and the screw 2 rotates at a low speed. do.

The first and second operating valves 17.20 are electromagnetic switching valves, and the first and second solenoids 17□.

Each solenoid is switched to each position by energizing 17*20+t20g, and each solenoid is energized and demagnetized by a control signal from the controller 26.

Note that the entire injection device is reciprocated by a cylinder 27.
Next, we will explain the operation of the autobarge.

With the screw 2 at the forward end, the second solenoid 17 is energized, the first operating valve 17 is at the extended position (■), and in this state, the second solenoid 17 is
The second trenoid 20° of the operation valve 20 is repeatedly energized and demagnetized multiple times at predetermined time intervals to switch between the neutral position N and the rotational position I multiple times at predetermined time intervals.

As a result, since the motor 13 repeats high-speed forward rotation and low-speed forward rotation multiple times at predetermined time intervals, the screw 2 repeats high-speed rotation and low-speed rotation multiple times at predetermined time intervals, so that the residual The molten resin is repeatedly fed at high speed and then at low speed, the flow changes rapidly, and the resin adhering to the threaded surface of the screw 2 is peeled off by inertia and sent out.

After the above-mentioned operation is completed, the first solenoid 201 of the second operating valve 20 is energized to the extended position I, and in this state, the first solenoid 201 is turned on.
The first and second solenoids 17 of the operation valve 17. , +7. Screw 2 is repeatedly energized and demagnetized multiple times at predetermined time intervals.
is reciprocated multiple times between the forward end and the backward end. As a result, the resin adhering to the wall surface of the hopper 1 is squeezed by the screw 2, peeled off, and sent out.

By repeating the above two operations multiple times, the remaining resin can be reliably discharged from the nozzle 4.

Effects of the Invention Since the resin attached to the screw surface of the screw 2 and the resin attached to the inner wall of the holder 1 can be peeled off and discharged, accumulation and
Resin that tends to stick can be effectively discharged.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of an injection device for carrying out the method of the present invention, and FIG. 2 is a control circuit diagram. 1 is the holder, 2 is the screw, and 4 is the nozzle.

Claims (1)

[Claims] In an injection device in which a screw 2 is provided in a cylindrical holder 1 having a nozzle 4 at its tip so as to be able to reciprocate and rotate freely between a forward end and a backward end on the nozzle 4 side, the screw 2 is moved forward. An injection device characterized in that the operation of repeating high-speed forward rotation and low-speed forward rotation at the end multiple times and the operation of reciprocating the screw 2 multiple times across the forward end and the backward end are repeated multiple times. Auto purge method.