JPH05220796A - Method for controlling plasticizing process of measured quantity of resin for injection molding machine - Google Patents

Abstract

PURPOSE:To provide a method for controlling plasticizing process of measured quantity of resin for injection molding machine wherein supplying quantity of melted resin is fixed and melted state is stabilized. CONSTITUTION:A rotation angle position detector 34 and a moving position detector 36 are provided at a rotary axis 30 of a screw 12 and a moving arm 32, respectively. These members are connected to an operation comparator 42 through interfaces 38 and 40. At the operation comparator 42, a travel speed ratio per unit rotating speed in all rotation angle positions in the whole process of the screw 12 is measured. By comparing the actually measured ratio with a reference value predetermined in a setting device 44, the screw is controlled so as to make the travel speed ratio of the screw coincide with the reference value through a controller 48 and a rotary drive section 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a resin melt plasticizing process in an in-line screw type injection molding machine.

[0002]

2. Description of the Related Art Generally, in an in-line screw type injection molding machine, a screw arranged in a barrel is rotationally driven to move the screw backward by a predetermined distance to melt and measure a predetermined amount of resin. When the screw moves forward again, the predetermined amount of the molten resin is injected into the mold to mold the product.

In such an injection molding machine, the screw is used in order to stabilize the molding cycle by stabilizing the supply amount (melting rate) of the molten resin and improve the molding quality by stabilizing the molten state. The rotation drive is controlled. The screw control method is usually such that the rotation speed of each rotation of the screw is controlled to be a reference value set in advance during an intermediate step of the screw (rotation speed constant control method), or In addition to control, the total plasticizing process, that is, the total process time from the rising process (starting of the measurement) to the intermediate process and the deceleration process (completion of the measurement) is set to a preset reference time (total process time). Constant control method).

[0004]

However, each of the above-mentioned conventional control methods has the basic drawbacks described below.

That is, in general, the resin is plasticized and melted when the solid raw material is bitten between the barrel and the screw and heated by compression, and the backward moving speed of the screw at this time is It is determined by the biting state of the screw. That is, the melting rate fluctuates to increase when the bite condition is good and decrease when the bite condition is bad. And this fluctuation of the melting rate is
Since the biting state of the screw is constantly changing, it always occurs, that is, even within one rotation of the screw.

However, in the conventional control method, the first constant rotation speed control method controls the rotation speed for each rotation to be constant, and the second whole process time constant control method. Similarly to the first method, it is also based on the substantially constant rotation speed method, that is, it does not control the rotation speed (rotational angular velocity) within each one rotation speed, and therefore the resin melting is constantly fluctuating. It was impossible to keep up with speed. Therefore, in the conventional control method, the melting rate of the resin (the supply amount of the molten resin per unit time) fluctuates and the properties of the molten resin become unstable, resulting in unstable molding cycle and molding quality. The result was a decline. Further, in the conventional control method, the abnormal state of the screw is configured to be judged by the upper limit of the driving power or the rotational speed of the screw or the difference in the process time, so that it is careless when the raw material of the resin runs out. There was also a risk that an idle operation would occur and the barrel and screw would come into direct metal contact with each other, resulting in an accident.

Therefore, an object of the present invention is to provide a method for controlling a resin measuring plasticizing process of an injection molding machine which can supply a molten resin having a constant melting rate and stable properties.

[0008]

In order to achieve the above-mentioned object, a method for controlling a resin measuring plasticizing process of an injection molding machine according to the present invention moves a screw at a constant rotation speed to move the screw backward. In a resin measuring plasticizing process control method of an injection molding machine that moves and melts and measures a resin, the rotational angular velocity and the backward moving velocity within each rotation of the screw are measured, and the backward moving velocity is moved per unit angle with respect to the rotational angular velocity. The rotation driving unit of the screw is controlled so that the speed ratio becomes a reference value set in advance during the measuring plasticizing step.

In this case, it is preferable to generate an alarm when the moving speed ratio of the screw per unit angle is out of an allowable range from a preset reference value.

Further, in this case, the measuring and plasticizing process is further divided into three process zones of a rising process, an intermediate process and a deceleration process, and the moving speed ratio of the screw per unit angle is preset for each of the process zones. It is configured to generate an alarm when it is outside the allowable range from each reference value, or the moving speed ratio per unit angle of the screw in the intermediate process zone is outside the allowable range from the preset reference value and is preset. An alarm may be generated and the screw rotation drive unit may be stopped or the screw rotation speed may be reduced when the error does not return to the allowable range within the determination time.

Further, according to the present invention, in a resin measuring plasticizing process control method of an injection molding machine in which a screw is driven at a constant rotational speed to move the screw backward to melt-measure the resin. By measuring the rotational angular velocity and the backward moving speed, and by comparing the moving speed ratio of the backward moving speed per unit angle to the rotational angular speed with a reference value set in advance during the plasticizing step, It is also characterized by monitoring the quality. Then, in this case, when the moving speed ratio of the screw per unit angle is out of the allowable range from the preset reference value, it is determined that the melting and measuring property of the resin is not good.

[0012]

According to the present invention, the screw is controlled so that the moving speed ratio per unit angle is constant at all positions within each rotation. In other words, the screw is controlled so that its backward moving speed (melting speed) is constant throughout the metering plasticizing process. Therefore, the supply amount of the molten resin becomes constant, the melting property is stabilized, the molding cycle is stabilized, and at the same time the molding quality is improved.

Further, according to the present invention, the abnormal state of the screw can be immediately detected and an alarm can be generated, so that the deterioration of the molten state of the resin can be reliably monitored, and the raw material is not carelessly cut. It is possible to prevent a metal contact accident with the barrel of the screw due to idling or the like.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a resin measuring plasticizing process control method for an injection molding machine according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram showing a schematic structure of an injection molding machine for carrying out the control method of the present invention and its control system. Therefore, referring to FIG. 1, first, the injection molding machine will be briefly described. The screw 12 is arranged in the barrel 10, and the screw 12 is driven at a constant rotation speed via the rotation drive unit 14, so that the screw 12 is driven. Drives backward for a predetermined distance, whereby a predetermined amount of the resin raw material 18 in the hopper 16 is melted and measured in the barrel space 10a. Then, the molten resin is injected into the mold (not shown) through the nozzle when the screw 12 moves forward again through the moving cylinder 20, and the product is molded by this. ing.

However, in the present invention, in order to control the operation of the screw 12, the rotary shaft 30 and the moving arm 32 of the screw 12 are provided with a rotational angle position detector 34 and a moving position detector 36, respectively, and These are connected to the operational comparator 42 via the interfaces 38 and 40, respectively. When the rotation driving unit 14 is composed of a servo motor, the rotation angle position detector 34 can use the rotation position detection encoder of the servo motor as it is. Then, the arithmetic comparator 42 is a setter 4 for setting the reference value and the allowable range.
4, the alarm 46 and the control unit 48, and the control unit 48 is connected to the rotation drive unit 14.

Next, the control operation of the injection molding machine according to the present invention having the above-mentioned structure will be described. When the screw 12 is rotated via the rotation driving section 14 and the measuring plasticizing step is started, the rotation angle is changed. The rotational angle position and the moving position signal of the screw measured by the position detector 34 and the moving position detector 36 are input to the arithmetic comparator 42 via the interfaces 38 and 40, respectively, and here, at each rotation of the screw. The rotational angular velocity and the backward moving velocity of the screw at all positions are calculated, and the moving velocity ratio per unit angular velocity (hereinafter simply referred to as moving velocity ratio) is calculated from them. Then, the arithmetic comparator 42 compares the moving speed ratio with a preset reference moving speed ratio inputted in the setter 44, and then the control unit 4 is operated.
2 by controlling the rotary drive unit 14 via
As shown in (3), the operation is performed so that all the moving speed ratios during the whole process of the screw 12 match the reference moving speed ratios. Similarly, an allowable error range of the reference moving speed ratio is preset in the setter 44, and as shown by the broken line in FIG. 2, when the moving speed ratio is out of the allowable range, the arithmetic comparator 42 The alarm 46 is activated to generate an alarm. The permissible range (particularly the upper limit) is set by the permissible speed of the screw peripheral speed determined by the type of resin.

As described above, according to the present invention, since the moving speed ratio of the screw is controlled to be constant at all positions during the entire process, the amount of the molten resin supplied is constant and the melting property is constant. Is stabilized, and thus the molding cycle is stabilized, and at the same time the molding quality is improved. Moreover, since an abnormal state of the screw is immediately detected and an alarm is issued, deterioration of the melting property can be reliably monitored, and a metal contact accident with the barrel of the screw due to idle operation such as running out of raw material can be prevented.

Next, FIG. 3 shows another embodiment of the control method according to the present invention. The present embodiment is configured such that, in addition to the embodiment shown in FIG. 1, the screw can be immediately stopped when an abnormality occurs in the screw. That is, the process comparator 50 is further connected to the process zone transmitter 52 and the stop controller 54 which are communicated to the interface 40, and the setter 56 is further provided with a timer for setting a determination time described later. Has been. In such a configuration, as shown by the broken line in FIG. 4, the moving speed ratio (set by the transmitter 52) is out of the allowable range and the determination time (set by the setter 56) is set in the intermediate process zone. If the operation comparator 50 does not return to the above-mentioned permissible range, the arithmetic comparator 50 activates the alarm 46 and, at the same time, the controllers 48 and 54 and the rotary drive unit 14 simultaneously.
Immediately stop the screw 12 via. Therefore, according to the present embodiment, the effects exhibited by the embodiment of FIG. 1 can be achieved more reliably.

Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the above embodiments, and many design changes can be made without departing from the spirit thereof. Moreover, it is needless to say that the present invention can be applied not only to the injection molding machine but also to the same type of apparatus.

[0021]

As described above, the method of controlling the plasticizing process of the resin for the injection molding machine according to the present invention drives the screw at a constant rotational speed to move the screw backward to melt and measure the resin. In the resin measuring plasticizing step control method for an injection molding machine, the rotational angular velocity and the backward moving speed in each rotation of the screw are measured, and the moving speed ratio per unit angle to the rotational angular speed of the backward moving speed is measured in the plasticizing step. Since the rotation drive unit of the screw is controlled so as to become the reference value set in advance during the period, the supply amount of the molten resin can be kept constant and the melting property can be stabilized. Therefore, the molding cycle of the injection molding machine is stabilized, and at the same time, the molding quality is improved.

Further, in the present invention, since the abnormal state of the screw can be immediately detected, the deterioration of the melting property can be reliably monitored, and the metal contact accident with the barrel of the screw due to the idle operation such as running out of raw material can be prevented. Can be prevented.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of an injection molding machine and a control system thereof as an embodiment of a resin measuring plasticizing process control method according to the present invention.

FIG. 2 is a characteristic diagram showing a change in moving speed ratio per unit angle in a control operation of the injection molding machine shown in FIG.

FIG. 3 is an explanatory diagram showing a schematic configuration of an injection molding machine and a control system thereof as another embodiment of the resin measuring plasticizing process control method according to the present invention.

FIG. 4 is a characteristic diagram showing a change in moving speed ratio per unit angle in a control operation of the injection molding machine shown in FIG.

[Explanation of symbols]

10 barrel 10a barrel space 12 screw 14 rotary drive unit 16 hopper 18 resin material 20 moving cylinder 22 nozzle 30 rotating shaft 32 moving arm 34 rotating angle position detector 36 moving position detector 38, 40 interface 42 arithmetic comparator 44 setter 46 Alarm 48 Control unit 50 Calculation comparator 52 Process zone transmitter 54 Stop controller 56 Setting device

Claims (6)

[Claims] 1. A method of controlling a resin measuring plasticizing process of an injection molding machine, wherein a screw is driven at a constant rotational speed to move the screw backward to melt-measure the resin. The backward moving speed is measured, and the rotation driving unit of the screw is controlled so that the moving speed ratio per unit angle of the backward moving speed to the rotational angular speed becomes a reference value set in advance during the measurement plasticizing step. Control method for resin measuring and plasticizing process of injection molding machine. 2. The moving speed ratio per unit angle of the screw is
The resin measuring plasticizing process control method for an injection molding machine according to claim 1, wherein an alarm is generated when the allowable range from a preset reference value is exceeded. 3. The measuring plasticizing process is divided into three process zones of a rising process, an intermediate process and a decelerating process, and a moving speed ratio of a screw per unit angle is based on respective reference values preset in each of the process zones. 3. The resin measuring plasticizing process control method for an injection molding machine according to claim 2, wherein an alarm is generated when the allowable range is exceeded. 4. An alarm is generated when the moving speed ratio per unit angle of the screw in the intermediate process zone is outside the allowable range from a preset reference value and does not return to the allowable range within a preset judgment time. The resin measuring plasticizing process control method for an injection molding machine according to claim 3, wherein the rotation driving part of the screw is stopped or the rotation speed of the screw is reduced. 5. A resin measuring plasticizing process control method for an injection molding machine, wherein a screw is driven at a constant rotation speed to move the screw backward to melt-measure the resin. The backward moving speed is measured and the moving speed ratio per unit angle of the backward moving speed with respect to the rotational angular speed is compared with a reference value set in advance during the plasticizing process for measuring the quality of the melting and measuring properties of the resin. A method of controlling a resin measuring plasticizing process of an injection molding machine, comprising: 6. The moving speed ratio of the screw per unit angle is
6. The resin measuring plasticizing process control method for an injection molding machine according to claim 5, wherein when the resin is out of an allowable range from each preset reference value, it is determined that the melting and measuring property of the resin is not good.