JPS62198417A - Method of automatically supplying material to injection molding machine - Google Patents

Abstract

PURPOSE:To contrive a reduction in defective molding which is due to dispersion in quantity of intrusion of resin, by a method wherein an injection stroke of a screw is found,a weight of material used for the last time injection molding is calculated and the material is supplied automatically to a hopper by an amount equivalent to this weight. CONSTITUTION:A fixed quantity of a material is supplied within a hopper beforehand. When molding is started, the retreatmost position of a screw at the time of completion of weighing, which is detected by a screw position detector 8 and an advancemost position after injection dwelling, that is, both of the positions showing remaining quantities are kept stored in a memory 6 and an injection stroke is found by deducting the advancemost position from the retreatmost position of the screw by an arithmetic unit 5. The material equivalent amount of used weight to the previous shot is supplied automatically to the hopper 1 by a material supply device 2 on an electric signal to be signaled every shot by a material supply starting signal generating device 9 by weighing the material sent from a material yard 3 by a material weighing device 4 by calculating one time injection quantity by multiplying the injection stroke by a fixed conversion value which has been preset by a coefficient presetting device 7.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an automatic material supply method for automatically supplying material to be injection molded from a material yard to a hopper of the machine in an injection molding machine. It is something.

``Prior Art'' Conventionally, in an injection molding machine, in order to supply the material to be injection molded from the material yard to the hopper of the machine, the material is simply fed from the material yard for a certain period of time set in the hopper log. It simply sucks it up and automatically supplies it to the hopper at regular intervals.

``Problem to be solved by the invention'' With the conventional and simple method described above, it is extremely difficult to balance the amount of material actually used and the amount of material supplied to the machine. , and if the amount of material used changes due to changes in molding conditions, etc., there will definitely be a difference between the amount supplied and the amount used.

Therefore, the material level in the hopper is constantly displaced, making it difficult to keep the swell constant.

Therefore, when the material is measured by rotating the screw, the weight of the material in the hopper changes, causing a problem in that the apparent specific gravity of the material changes and the injection weight of the material is not constant.

``Means for Solving the Problems'' The present invention improves the material feeding method as described above, and provides a solution to the hopper by feeding the material equivalent to the weight of the material used in the previous shot to the hopper for each shot. Focusing on the fact that the level of the material inside the screw is always constant, this is automatically controlled, and a screw position detection device is used to determine the screw's most retracted position and the screw's most advanced position. The injection stroke is determined by subtracting the most forward position of the screw from the most retracted position of the screw using the arithmetic unit. The weight of the material used for the previous injection molding is calculated by multiplying the injection stroke by the converted value, and the material for the previous time is automatically supplied from the material yard to the hopper. It is.

``Function'' It detects both the screw's most retracted position at the time of completion of metering, which is detected by the screw position detection device of the injection molding machine, and the screw's most forward position during injection holding pressure (this means the remaining amount of material to be injected). Store it in a storage device.

Next, this is input into a calculation device, and the injection stroke is determined by subtracting the most advanced position (remaining amount) of the screw from the most retracted position of the screw.

On the other hand, the weight used for 〒 injection molding is calculated by multiplying the injection stroke by a preset conversion value using the coefficient setting device, for example, the cylinder inner area multiplied by a certain coefficient. do. Needless to say, this calculated weight means the ejection weight of the previous shot.

This is then input into the material weighing device, which measures the previous calculated weight, and then sends it to the hopper based on the electric signal for each shot sent from the material supply start signal generator installed on the other side. Automatically supplies materials.

"Example" This will be explained based on the graph of the drawing showing one example of the method of the present invention.

Before the injection molding machine starts molding, a certain amount of material is supplied into the hopper in advance.

When molding is started, both the most retracted position of the screw at the time of completion of metering detected by the screw position detection device 8 and the most forward position of the screw after the injection and holding pressure, that is, the position indicating the remaining amount, are stored in the memory bag e6. Then, the calculation device 5 calculates the injection stroke by subtracting the most advanced position of the screw from the most retracted position of the screw.

Then, the constant conversion value set by the coefficient setter 7 is
The weight of one injection is calculated by multiplying the injection stroke, and the material sent from the material yard 3 is transferred to the material weighing device 4.
Based on the electric signal transmitted every shot by the material supply start signal generator 9, the material corresponding to the weight used in the previous shot is automatically supplied to the hopper 1 by the material supply device 2.
Supplied with

By doing so, the amount of material supplied to the hopper 1 and the supply interval can be manually set accurately.

"Effects of the Invention" According to the method of the present invention, the material level in the hopper is always constant during injection molding with an injection molding machine, so the material in the hopper is guided into the screw groove and sent forward by the rotation of the screw. This stabilizes the so-called resin penetration amount, making it possible to reduce molding defects caused by variations in the resin penetration amount.

[Brief explanation of drawings]

The drawing is a graph showing one embodiment of the method of the present invention. ■、・、。 0. Hopper 3. ,,,,Material yard 4
．． ,,,,Material measuring device 5. ,,,,Arithmetic device 6.
,,,,Storage device? , , , Coefficient setter 8□10.
Screw position detection device

Claims (1)

[Claims] The screw position detection device detects the most retracted position of the screw and the most advanced position of the screw, this is stored in the memory device, and the calculation device subtracts the most advanced position of the screw from the most retracted position of the screw to obtain the injection stroke. At the same time, the coefficient setter multiplies the injection stroke by a preset conversion value to calculate the weight of the previous material used for injection molding. An automatic material feeding method for an injection molding machine that automatically feeds materials from the yard to the hopper.