JPH10329200A - Method and apparatus for controlling composite extrusion molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately control by detecting a pressure of an inlet side of a gear pump, separating its variation into a long period component and a short period component, and respectively controlling material supply amount and screw rotational speed by them. SOLUTION: A pressure detector 6 is provided at an inlet side of a gear pump 3. Pressure P1 of the inlet side of the pump detected here is input to a low pass filter 7 and high pass filter 8. The filter 7 extracts a pressure change signal of a long period component of the pressure P1, and inputs it to a first controller 9. Meanwhile, the filter 8 extracts a pressure change signal of a short period component of the pressure P1, and inputs it to a second controller 11. And, the controllers 9, 11 respectively output control signals so that the pressures of the pump inlet side become set pressure, input them to a drive motor 10 and drive motor 13, and control material supply amount to be supplied from a quantitative feeder 1 to a biaxial extruder 2 and screw rotating speed of the extruder 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method and a control apparatus for a composite extrusion molding apparatus in which a synthetic resin molding material kneaded by a screw of an extruder is discharged by a gear pump.

[0002]

2. Description of the Related Art
In the compound extrusion molding apparatus as described above, in order to stabilize the discharge amount of the gear pump and improve the dimensional accuracy of the molded product, the rotational speed of the screw of the extruder is controlled by the suction pressure of the gear pump, and the extruder is controlled. It has been proposed to control the amount of material supplied to the system.

[0003] However, in this type of apparatus, since the material stays in the extruder for a long time, as described above, when the amount of material supplied to the extruder is controlled only by the suction pressure of the gear pump, it is difficult to control the amount of material supplied to the extruder. The influence of the change in the material supply amount remains for a long time, it is difficult to remove the pressure fluctuation, and even if the rotation speed of the screw of the extruder is controlled by the suction pressure of the gear pump, the detected pressure value is longer than the long period. , The response to short-period pressure fluctuations is not always fast.

[0004] In view of the above, the present invention provides an accurate control of a composite extrusion molding apparatus without the above-mentioned disadvantages.
It is an object of the present invention to obtain a control method and a control device capable of keeping the accuracy of a product constant.

[0005]

Means for Solving the Problems A first invention of the present application is directed to a quantitative feeder for supplying a raw material to an extruder under quantitative control, an extruder for supplying the raw material from the quantitative feeder, and an extrusion side of the extruder. A method for controlling a compound extrusion molding apparatus having a gear pump connected to a gear pump, comprising detecting a pressure at an inlet side of the gear pump, separating a change in the pressure into a long-period component and a short-period component, The amount of material supplied to the fixed-quantity feeder is controlled so that the pressure on the inlet side of the gear pump becomes the set pressure by the pressure fluctuation, and the screw rotation speed of the extruder is controlled by the pressure fluctuation of the short-period component.

According to a second aspect of the present invention, there is provided a quantitative feeder for supplying a raw material to an extruder under quantitative control, an extruder for supplying the raw material from the quantitative feeder, and a gear pump connected to the extrusion side of the extruder. In the control method of the compound extrusion molding apparatus having the above, detecting the pressure on the inlet side and the pressure on the outlet side of the gear pump, separating the fluctuation of the differential pressure into a long-period component and a short-period component, It is characterized in that the material supply amount of the fixed-quantity feeder is controlled so that the pressure on the inlet side of the gear pump becomes a set pressure by the pressure fluctuation, and the screw rotation speed of the extruder is controlled by the fluctuation of the differential pressure of the short-period component.

In a third aspect of the present invention, there is provided a quantitative feeder for supplying a raw material to an extruder under quantitative control, an extruder for supplying the raw material from the quantitative feeder, and a gear pump connected to the extrusion side of the extruder. A control device for the compound extrusion molding apparatus, comprising: a pressure detector for detecting a pressure on the inlet side of the gear pump; a low-pass filter for extracting a long-period component of a fluctuation signal of the pressure detected by the pressure detector; A high-pass filter that extracts a short-period component of the fluctuation signal of the first control device, a first control device that controls a fixed amount of material supplied to the feeder by the pressure fluctuation signal extracted by the low-pass filter, and a pressure fluctuation signal that is extracted by the high-pass filter. A second control device for controlling the screw rotation speed of the extruder.

[0010] A fourth aspect of the present invention provides a quantitative feeder for supplying a raw material to an extruder under the above-mentioned quantitative control, an extruder for supplying the raw material from the quantitative feeder, and a gear pump connected to the extrusion side of the extruder. A first pressure detector for detecting a pressure on an inlet side of the gear pump, a second pressure detector for detecting a pressure on an outlet side of the gear pump, and both pressure detectors. A low-pass filter for extracting a long-period component of the fluctuation signal of the differential pressure of the pressure detected in the above, a high-pass filter for extracting a short-period component of the fluctuation signal of the differential pressure, and a pressure fluctuation signal extracted by the low-pass filter. A first control device for controlling a material supply amount, and a second control device for controlling a screw rotation speed of an extruder based on a pressure fluctuation signal extracted by a high-pass filter. Characterized in that it has and.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram of a control device of a composite extrusion molding apparatus according to the present invention,
The raw material supplied from the fixed-quantity feeder 1 to the twin-screw extruder 2 is:
The mixture is heated and melted while being kneaded by the twin-screw extruder and fed to the gear pump 3, where the raw material continuously conveyed from the twin-screw extruder 2 is measured by a fixed amount, and is passed through the filter 4 to the die 5. Supplied.

A pressure detector 6 is provided on the inlet side of the gear pump 3, and the pressure P1 on the gear pump inlet side detected by the pressure detector 6 is input to a low-pass filter 7 and a high-pass filter 8, respectively. The low-pass filter 7 extracts a long-period component pressure fluctuation signal of the gear pump inlet-side pressure P <b> 1, and inputs the long-period pressure fluctuation signal to the first controller 9. Then, a control signal is output from the first control device 9 so that the pressure on the gear pump inlet side becomes the set pressure, and the control signal is input to the drive motor 10 of the fixed-quantity feeder 1. The amount of raw materials supplied from the feeder 1 to the twin-screw extruder 2 is controlled.

On the other hand, the high-pass filter 8 extracts a short-period component pressure fluctuation signal of the gear pump inlet-side pressure P 1, and inputs the short-period pressure fluctuation signal to the second controller 11. Then, the second control device 11
Outputs a control signal such that the pressure on the inlet side of the gear pump becomes the set pressure, the control signal is input to the drive motor 12 of the twin-screw extruder 2, and the screw rotation speed of the twin-screw extruder is controlled. FIG. 2 shows a control flow in the control device.

Thus, the fixed-quantity feeder is controlled by the pressure fluctuation signal of the long-period component of the pressure on the inlet side of the gear pump, and the disturbance due to the change in the characteristic of the fixed-quantity feeder is corrected. The screw rotation speed of the extruder is controlled, the screw rotation speed of the extruder quickly responds to the pressure fluctuation, and the fluctuation width is controlled to be small. That is, by controlling the fixed-quantity feeder and the twin-screw extruder with the pressure fluctuation signal of the long-period component and the pressure fluctuation signal of the short-period component, both the long-period fluctuation and the short-period fluctuation can be eliminated, respectively. Control is performed so that the fluctuation is reduced.

In the above embodiment, the fixed-quantity feeders 1 and 2 are controlled by the pressure on the inlet side of the gear pump 3.
The screw rotation speed of the screw extruder 2 is controlled. However, the screw rotation speed of the fixed feeder and the twin screw extruder may be controlled by the pressure difference between the inlet side and the outlet side of the gear pump 3. Good. That is, the change in the supply amount of the fixed amount feeder always appears as a change in the differential pressure before and after the gear pump. Therefore, by controlling the fixed-quantity feeder and the like by the differential pressure, it is possible to cope with the disturbance.

FIG. 3 is a diagram showing an embodiment in which the control based on the differential pressure is performed. A first pressure detector 6 and a second pressure detector 1 are provided on the inlet side and the outlet side of the gear pump 3.
The two pressure signals detected by the first pressure detector 6 and the second pressure detector 13 are compared with each other by a differential pressure calculator 14, and the differential pressure is calculated by a low-pass filter 7.
The high-pass filter 8 controls the fixed-quantity feeder 1 by the long-period component of the differential pressure fluctuation, and controls the screw rotation speed of the twin-screw extruder 2 by the short-period component.

In this case, too, the feeder supply amount is controlled by the long-period component of the pressure difference between the inlet side and the outlet side of the gear pump 3, the screw rotation speed is controlled by the short-period component, and the long-period component is controlled. The control of the short-period component is executed in a shared manner, the mutual complement function is utilized, and accurate control over a wide range is performed.

[0016]

As described above, according to the present invention, the fluctuation of the pressure on the inlet side of the gear pump or the fluctuation of the pressure difference between the inlet side and the outlet side is divided into a long-period component and a short-period component. And the screw rotation speed of the twin-screw extruder is controlled, so that both the control of the long-period component and the control of the short-period component can be shared and executed together, and the fluctuations of both periods can be complemented by each other. As a result, the pressure fluctuation at the inlet of the gear pump can be reduced, and the product accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing a control flow of the apparatus shown in FIG.

FIG. 3 is a block diagram showing another embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 fixed-quantity feeder 2 twin-screw extruder 3 gear pump 4 filter 5 die 6 pressure detector 7 low-pass filter 8 high-pass filter 9 first control device 11 second control device 13 second pressure detector 14 differential pressure calculator

Claims (4)

[Claims] 1. A composite extrusion molding apparatus comprising: a fixed-quantity feeder for supplying a raw material to an extruder under quantitative control; an extruder for supplying the raw material from the fixed-quantity feeder; and a gear pump connected to an extrusion side of the extruder. In the control method of the device, the pressure on the inlet side of the gear pump is detected, and the fluctuation of the pressure is separated into a long-period component and a short-period component. Control the material feed rate of the fixed-quantity feeder so that
A method for controlling a compound extrusion molding apparatus, wherein a screw rotation speed of an extruder is controlled by a pressure fluctuation of a short-period component. 2. A composite extrusion molding machine comprising: a fixed-quantity feeder for supplying a raw material to an extruder under quantitative control; an extruder for supplying the raw material from the fixed-quantity feeder; and a gear pump connected to the extrusion side of the extruder. In the control method of the device, the pressure on the inlet side and the pressure on the outlet side of the gear pump are detected, and the fluctuation of the differential pressure is separated into a long-period component and a short-period component. Type extrusion molding machine characterized by controlling the amount of material supplied to the fixed-quantity feeder so that the inlet pressure of the extruder becomes the set pressure, and controlling the screw rotation speed of the extruder by the fluctuation of the differential pressure of the short-period component. Control method. 3. A composite extrusion molding machine comprising: a fixed-quantity feeder for supplying a raw material to an extruder under quantitative control; an extruder for supplying the raw material from the fixed-quantity feeder; and a gear pump connected to the extrusion side of the extruder. In the control device of the apparatus, a pressure detector for detecting the pressure on the inlet side of the gear pump, a low-pass filter for extracting a long-period component of the fluctuation signal of the pressure detected by the pressure detector, A high-pass filter for extracting a periodic component, a first controller for controlling a fixed amount of material supplied to a feeder based on a pressure fluctuation signal extracted by a low-pass filter, and a screw rotation of an extruder based on a pressure fluctuation signal extracted by the high-pass filter. A control device for controlling the speed, the control device for a composite extrusion molding device. 4. A composite extrusion molding machine comprising: a fixed-quantity feeder for supplying a raw material to an extruder under quantitative control; an extruder for supplying the raw material from the fixed-quantity feeder; and a gear pump connected to the extrusion side of the extruder. A first pressure detector for detecting a pressure on the inlet side of the gear pump;
A second pressure detector for detecting the pressure on the outlet side of the gear pump; a low-pass filter for extracting a long-period component of a fluctuation signal of the differential pressure of the pressures detected by the two pressure detectors; A high-pass filter that extracts the periodic component,
A first control device for controlling the material supply amount of the fixed-quantity feeder based on the pressure fluctuation signal extracted by the low-pass filter, and a second control device for controlling the screw rotation speed of the extruder based on the pressure fluctuation signal extracted by the high-pass filter. A control device for a composite extrusion molding device, comprising: