JPH0596586A - Controller for injected resin quantity - Google Patents

Abstract

PURPOSE:To supply the screw head side smoothly with a resin lost by a back flow by reversing a screw body and making rear pressure on the screw body side of a check ring higher than front pressure on the screw head side after a weighing process. CONSTITUTION:A resin pushes and forward moves a check ring 104 with the rotation of a screw in a heating cylinder 101, and a screw body 102 starts its retreat with the supply of the resin to the screw head 103 side while weighing is conducted. A driving motor 108 is operated by confirming relationship, in which pressure (a) on the screw head 103 side is made smaller than or the same as pressure (b) on the screw body 102 side while holding the check ring 104 when weighing reaches a fixed value, by sensors 105, 106, and the screw body 102 is reversed. When a fine clearance is formed between the check ring 104 and the screw body 102 and rear pressure (b) is made larger than front pressure (a), the screw head 103 sidle is supplied with the resin and the resin reaches a fixed quantity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw main body for advancing or retreating in a heating cylinder of an injection molding machine, and a control device for an injection amount of resin by adjusting front and rear pressures of a check ring.

[0002]

2. Description of the Related Art In an injection molding machine, it is known that the screw main body is slightly retracted in order to prevent leakage of molten resin (hereinafter simply referred to as resin) from a nozzle portion when a measuring process is completed.

However, in the check ring, since the resin pressure difference between the front part and the rear part of the check ring becomes equal due to the retreat of the screw main body, the position of the check ring may become uncertain if it is a little.

When injection is performed without confirming the indefiniteness, retreat is started when the pressure on the screw head side of the check ring becomes slightly higher than the pressure on the screw body side during the injection process.

During this time, the resin continues to backflow, which causes unstable injection amount.

[0006]

Therefore, in the present invention, after the measuring process, the screw main body is reversed to increase the rear pressure on the screw main body side of the check ring to be higher than the front pressure on the screw head side and at the same time. It is a technical problem of the present invention to store a predetermined amount of resin by supplying the resin from the side to the screw head side.

[0007]

Means for solving the above technical problems are as follows. A heating cylinder with a check ring between the screw body and screw head,
A sensor provided at a required position to confirm that the resin measuring process in the heating cylinder has been completed, a mechanism for reversing and stopping the screw body in response to a command from the sensor, and the like. The reverse pressure causes the rear pressure on the screw body side of the check ring to be higher than the front pressure on the screw head side.

[0008]

A check ring is attached to the screw head side in the heating cylinder of the injection molding machine, and when the resin is sent forward through the check ring and reaches a predetermined amount (measurement process), the screw works by the sensor. When the main body is slightly reversed and the screw is stopped instantly, a slight gap is formed between the check ring and the screw main body, so the rear pressure on the screw main body side is higher than the front pressure on the screw head side. At the same time, the resin is sent to the screw head side.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An in-line screw type injection molding machine, which is a preferred example of one embodiment of the present invention, will be described below with reference to the drawings.

A check ring 104 is formed on the screw head 103 side of a screw main body 102 mounted in the heating cylinder 101 so as to be able to rotate normally or reversely.

Limit switches 105 and 106 are formed behind the screw body 102 to indicate a retracted position or an advanced position of the screw body 102.

Further, a screw driving gear 107 is formed on a rear screw shaft 113 of the screw body 102, and a screw driving motor 108 and an encoder 10 are provided.
9 is formed, and a hydraulic device 110 for advancing the screw main body 102 is formed.

With the above-described structure, the material supplied from the hopper 111 into the heating cylinder 101 advances as the screw body 102 rotates in the normal direction, and passes through the check ring 104 and is supplied to the screw head 103 side. As the screw body 102 starts to move backward, weighing is performed at the same time, and when a predetermined amount is reached, the screw main body 102 is stopped by the operation of one of the sensors, for example, the limit switch 106.

When the screw motor 102 is stopped, the drive motor 108 starts to rotate in the reverse direction, and the encoder 109 responds at the same time, and when the screw body reaches the required rotation angle,
Along with the operation of the encoder 109, the drive motor 108
Stop rotating.

Next, an example in which a hydraulic motor is used instead of the screw drive motor 108 will be described with reference to the hydraulic circuit shown in FIG.

At the time of measurement, the solenoid valve b of DS1
The pressure oil is sent to the hydraulic motor 112 by the excitation of (S0L · b), the screw main body 102 is rotated in the normal direction, and when the measurement is completed, the reverse rotation is performed by exciting the DS2, S0L · b.

The reversing time is adjusted by a timer, and the proper time is set, since the closing time of the check ring varies depending on the screw rotation speed, the material, and the like.

[0018]

Since the present invention is constructed as described above, the resin pushes the check ring forward as the screw in the heating cylinder rotates, and the screw body moves backward as it is supplied to the screw head side. When the metering is started and the predetermined metering is reached, a check ring is sandwiched between the screw head side pressure a and the screw body side pressure b. The motor runs,
When the screw body is reversed and a small gap is formed between the screw body and the check ring, when the rear pressure b on the screw body side becomes larger than the front pressure a on the screw head side, the resin is supplied to the screw head side. , Reach a certain amount.

Next, due to the ejection force applied to the hydraulic ram of the injection cylinder, the screw main body rapidly advances, and the resin on the screw head side is injected at high speed from the nozzle into the mold.

In short, since the shortage of the injection amount caused by the backflow is filled with the resin supplied to the screw head side due to the minute gap formed between the check ring and the screw side due to the reverse rotation of the screw body, the predetermined injection is performed. The amount is obtained.

The command from the sensor for notifying the end of the resin measuring process is preferably mechanical, such as a cam or gear, or electrically, such as a limit switch or a proximity switch.

An encoder or a timer is preferably used to measure the rotation angle of the drive motor.

[Brief description of drawings]

FIG. 1 is a schematic overall view of a device of the present invention.

FIG. 2 is a hydraulic circuit when a hydraulic motor is used instead of the drive motor of the device of the present invention.

FIG. 3 is a block diagram illustrating an outline of the device of the present invention.

[Explanation of symbols]

 101 is a heating cylinder 102 is a screw main body 103 is a screw head 104 is a check ring 105 and 106 are limit switches (sensors)

Claims (1)

[Claims] 1. A heating cylinder provided with a check ring between a screw body and a screw head, a sensor provided at a required position for confirming that the resin measuring process in the heating cylinder has been completed, and the sensor. A mechanism for reversing and stopping the screw main body in response to a command, etc., and the rear pressure of the check ring on the screw main body side is made higher than the front pressure on the screw head side by the reverse rotation of the screw main body. Control device for the injection amount of resin.