JP2002178392A - Controlling apparatus and method for controlling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controlling method of an extruder which enables stable extrusion upon starting up the extruder. SOLUTION: A controlling method of an extruder comprises a process of conducting an open loop control of a rotation number of a screw 3 to extrude a molten material in a barrel 4 to a die 5 based on a target value with a screw control portion 14 and a process of conducting a feed back control of a rotation number of a gear pump 6 to supply the raw material in the barrel to a die 5 based on an inlet pressure of the gear pump with a gear pump control portion 13 wherein in this operation at first a differential preceding operation and a proportional preceding operation are conducted based on the inlet pressure and when the inlet pressure rises to a predetermined value, the differential preceding operation is conducted based on the inlet pressure and a proportional integral operation is conducted based on a deviation between the inlet pressure and a target pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device and a control method for an extruder used for obtaining plastic molded products such as sheets and films.

[0002]

2. Description of the Related Art Generally, an extruder for producing a plastic molded product such as a sheet or a film has a barrel in which a screw for kneading a raw material is arranged and a heater for heating and melting the raw material is provided. A fixed-quantity feeder for supplying the raw material into the barrel, a die for guiding the raw material kneaded and melted in the barrel to form a predetermined thickness and width, and disposed between the cylindrical body and the die A gear pump for keeping the discharge amount of the molten raw material constant is provided.

[0003] The operating state of an extruder is roughly classified into three types: start-up, steady-state operation in which a molded product is produced, and stoppage. In the steady-state operation, the raw material fills the barrel. In a stable situation, constant value control using a normal PID controller or the like has been performed in order to maintain a constant barrel pressure and gear pump rotation speed. In particular, in an extruder having a gear pump, during steady operation, in order to keep the inlet pressure (hereinafter, referred to as inlet pressure) constant, screw speed control is performed by feeding back the inlet pressure, and gear pump speed control is performed. In general, open loop control for maintaining a predetermined number of rotations is performed (for example, see Japanese Patent Application Laid-Open No. 8-132516).

[0004]

However, although the automatic operation of the steady state operation is performed as described above, the operation of the extruder is not completely automated from the time of start-up to the time of stoppage. In some cases, the operation of the extruder at the time of stoppage must rely on manual operation by a skilled operator.

[0005] Because, at the time of startup, immediately after the start of the operation of the screw, the barrel gradually fills with the raw material. However, the inlet pressure of the gear pump is almost zero before the raw material fills the barrel and reaches the gear pump, and it does not make sense to operate the gear pump to adjust the gear pump inlet pressure to a certain value. On the other hand, when the raw material is filled, the gear pump inlet pressure starts to increase, but greatly changes depending on the rotation speed of the gear pump.

Further, from the start of starting, the gear pump rotation speed is set to PI to maintain the gear pump inlet pressure at a predetermined target value.
When the D control is performed, the pressure deviation remains generated at least until the raw material is filled, so that the function of the integrating operation becomes stronger. In this situation, when the raw material is filled, the operation of the integration operation for the accumulated pressure deviation becomes dominant, so that the rotation speed of the gear pump does not immediately rise and the pressure at the gear pump inlet easily exceeds the dangerous value. However, considering that the operation eventually shifts to the steady operation, the integration operation is indispensable in the gear pump rotation speed control in order to follow the changed target value.

[0007] Therefore, in the control at the time of starting the extruder, it is difficult to apply ordinary constant value control or follow-up control because of the above transient characteristics. Further, even at the time of stoppage, it is difficult to apply ordinary constant value control or follow-up control because of transient characteristics such as a decrease in the amount of raw material in the barrel.

On the other hand, at the time of start-up, the transition from the operation stop state to the control state at the time of steady operation is performed, and at the time of stop, the transition from the control state at the time of steady operation to the operation stop state is performed.

Accordingly, an object of the present invention is to provide a control device and a control method of an extruder capable of performing stable extrusion at the start of operation, at the time of steady operation, and at the time of stop of operation.

[0010]

According to a first aspect of the present invention, there is provided a control apparatus for an extrusion molding machine, comprising: a cylindrical casing in which a screw for kneading raw materials is arranged; A die for guiding the raw material kneaded and melted to form a predetermined thickness and width, a gear pump disposed between the cylindrical casing and the die for maintaining a constant discharge amount of the raw material, A rotary drive for a screw for rotating a screw, a rotary drive for a gear pump for rotating a gear pump, and a pressure detector for detecting an inlet-side pressure of the gear pump; A target value setting section for setting the target values of the screw rotation speed and the pressure on the inlet side of the gear pump, and inputting the detected pressure from the pressure detector to the gear. A gear pump control unit for controlling the rotation speed of the pump rotary drive, a screw control unit for inputting the detection pressure from the pressure detector to control the rotation speed of the screw rotary drive, and the detection pressure unit. A control operation switching unit that can change each target value according to the input detected pressure and that switches a control operation in each of the control units, and wherein the target value set by the target value setting unit is a plurality of With a step value of
The switching between the step values and the switching of the control operation are performed based on the detected pressure.

According to this configuration, the target value can be changed and the control operation can be switched on the basis of the state of the inlet side pressure. It also enables stable operation.

A control device for an extruder according to a second aspect of the present invention includes a cylindrical casing in which a screw for kneading a raw material is disposed, and a guide for guiding the raw material kneaded and melted in the cylindrical casing. A die that is formed between the cylindrical casing and the die, a gear pump for maintaining the discharge amount of the raw material constant, and a screw rotary drive and a gear pump that rotate the screw. What is claimed is: 1. A control device for an extruder, comprising: a rotary drive for a gear pump to be rotated; and a pressure detector for detecting an inlet pressure of the gear pump. A target value setting unit for setting a target value of the gear pump, and a detection pressure from the pressure detector to control the rotation speed of the rotary driving machine for the gear pump. A gear pump control unit, a screw control unit for inputting a detected pressure from the pressure detector to control a rotation speed of the screw rotary drive, and a target for each target according to the detected pressure input from the detection pressure device. A control operation switching unit that can change the value and change the control operation in each of the control units. The gear pump control unit outputs the target rotation speed from the target value setting unit to the gear pump rotary drive as a control value. A first target value output path section for inputting a detected pressure from a pressure detector, generating a command rotational speed based on the detected pressure, and outputting the generated command rotational speed as a control value to a gear pump rotary drive. The first command value output path section is configured to perform a differential leading operation section that performs a differential leading operation by inputting a detected pressure, and a proportional leading operation that receives a detected pressure. A proportional leading operation unit, a proportional integration unit provided in parallel with the proportional leading operation unit and performing a proportional integration operation by inputting a deviation between a target pressure and a detected pressure, and an output and a proportional integration from the proportional leading operation unit And a control change unit for subtracting one of the outputs from the output unit from the output from the differential operation unit, and a target rotation speed from the first target value output path unit and a control change unit from the first command value output path unit. A first control switching unit is provided which outputs any one of the commanded rotation speeds as a control value to the gear pump rotary drive.

According to a third aspect of the present invention, there is provided a control device for an extruder, wherein the screw control unit in the control device according to the second aspect is configured such that the screw control unit uses the target rotation speed from the target value setting unit as a control value. And a second target value output path for inputting the detected pressure from the pressure detector, generating a commanded rotational speed based on the detected pressure, and outputting the commanded rotational speed as a control value to the screw rotary drive. And a path section, wherein the second command value output path section receives a detected pressure and performs a differential leading operation,
A proportional-integral operation unit for inputting a deviation between the target pressure and the detected pressure to perform a proportional-integral operation and adding the result to the output from the differential operation unit, and a target rotational speed and a target rotational speed from the second target value output unit. A second control switching unit is provided which outputs any of the command rotation speeds from the second command value output unit as a control value to the screw rotary drive machine.

According to a fourth aspect of the present invention, there is provided a control device for an extruder, wherein at least a proportional value is set to each target value at the time of starting operation set by a target value setting section in the control device according to the second or third aspect. A control change step value that changes the control from the preceding operation to the proportional-integral operation, and switching from control based on the target rotation speed of the screw to control based on the inlet pressure, and control based on the target rotation speed based on control based on the inlet pressure of the gear pump. This is provided with a control switching step value for switching to.

According to the configuration of the second to fourth aspects, the gear pump control unit and the screw control unit can switch between the open loop control based on the target value and the feedback control based on the inlet pressure, respectively. In the part, since it is possible to change the proportional leading operation and the proportional integration operation,
For example, at the start of operation, the screw can be rotated at a predetermined rotation speed, and at the same time, the function of the integration operation becomes dominant when the raw material is filled, and the rise of the inlet pressure can be suppressed. That is, the operation at the time of starting can be performed automatically, safely and quickly.

According to a fifth aspect of the present invention, there is provided a control device for an extruder, wherein each target value at the time of operation stop set by a target value setting section in the control device according to any one of the second to fourth aspects is At least the control at the gear pump rotation speed includes a control change step value for changing the control from the differential leading operation and the proportional integration operation based on the inlet pressure to the differential leading operation and the proportional leading operation based on the inlet pressure. The control switching unit stops the rotation of the screw when the current value of the screw rotary drive becomes equal to or less than a predetermined value.

According to this configuration, when the operation is stopped, the rotational speed of the screw is reduced, and the control of the gear pump is changed from the differential leading operation based on the inlet pressure and the control based on the proportional integral operation to the differential leading operation. Since the operation is changed to the proportional preceding operation, it is possible to safely and quickly shift from the steady operation to the stop state.

According to a sixth aspect of the present invention, there is provided a method for controlling an extruder, comprising: introducing a cylindrical casing in which a screw for kneading a raw material is disposed, and a raw material kneaded and melted in the cylindrical casing. A die for molding to a predetermined thickness and width, a gear pump disposed between the cylindrical casing and the die to maintain a constant discharge rate of the raw material, a screw rotary drive and a gear pump for rotating the screw A method for controlling an extruder having a rotary drive for a gear pump for rotating a gear pump and a pressure detector for detecting the pressure on the inlet side of the gear pump, wherein at the start of operation, the rotation speed of the screw is set to a target value setting unit. Control based on the target value from the motor, and control the rotational speed of the gear pump by the differential leading operation and the proportional leading operation based on the inlet pressure. When inlet pressure reaches a predetermined value,
The rotational speed of the gear pump is controlled by a differential leading operation based on the inlet pressure and a proportional integral operation based on the deviation between the inlet pressure and the target pressure. When the inlet pressure reaches the control switching step value, the screw rotational speed is controlled. Is switched to control based on the inlet-side pressure, and the rotational speed of the gear pump is switched to control based on the target rotational speed.

In the method for controlling an extruder according to a seventh aspect of the present invention, a cylindrical casing in which a screw for kneading a raw material is disposed and a raw material kneaded and melted in the cylindrical casing are guided. A die for molding to a predetermined thickness and width, a gear pump disposed between the cylindrical casing and the die to maintain a constant discharge rate of the raw material, a screw rotary drive and a gear pump for rotating the screw A rotary driving device for a gear pump for rotating the gear pump, and a pressure detector for detecting the pressure on the inlet side of the gear pump, wherein when the operation is stopped, the rotation speed of the screw is set to a target value setting unit. Control based on the target rotation speed from, and the rotation speed of the gear pump is set to the differential leading operation based on the inlet pressure and the inlet pressure and target pressure. Performs control by proportional integrating operation based on the deviation, the inlet pressure becomes the raw material discharge waiting step value, the rotational speed of the gear pump, a method for performing control based on the differential preceding operation and proportional advanced operation based on inlet pressure.

According to a control method of an extruder according to an eighth aspect of the present invention, in the control method of the twelfth aspect, the current value in the screw rotary drive after the inlet-side pressure stabilizes to the raw material discharge waiting step value. Is a method of shifting the target values of the screw, the gear pump, and the inlet pressure to zero when the pressure becomes equal to or less than a predetermined value.

According to the control method according to the sixth to eighth aspects, similarly to the operation according to the first to fifth aspects, the change of the target value and the control operation based on the state of the inlet side pressure are performed. Since the switching can be performed, a stable operation can be performed at the time of starting operation and at the time of stopping operation even if there is a transient fluctuation in the inlet pressure.

The gear pump control section and the screw control section each switch between open loop control based on the target value and feedback control based on the inlet pressure, and the gear pump control section changes the proportional preceding operation and the proportional integration operation. It is possible to rotate the screw at a predetermined rotation speed, for example, at the start of operation,
When the raw material is filled, the function of the integration operation becomes dominant and the rise of the inlet pressure can be suppressed. That is, the operation at the time of starting can be performed automatically, safely and quickly.

Further, when the operation is stopped, the rotational speed of the screw is reduced, and the control of the gear pump is changed from the differential leading operation based on the inlet pressure and the proportional integral operation to the differential leading operation and the proportional leading operation. Therefore, it is possible to safely and quickly shift from the steady operation to the stopped state.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a control device and a control method for an extruder according to an embodiment of the present invention will be described with reference to FIGS.
It will be described based on.

First, a schematic configuration of the extruder will be described with reference to FIG. The extruder 1 is provided with a raw material supply hopper 2 for supplying a resin raw material along the way, a screw 3 for kneading the raw material therein is rotatably disposed, and a heater (heater) as a heating means for heating and melting the raw material. A cylindrical barrel (an example of a cylindrical casing, also referred to as a cylinder) 4 provided with a not-shown) and a molten material kneaded and melted in the barrel 4 are guided and formed into a predetermined thickness and width. A die 5 and a gear pump 6 arranged between the barrel 4 and the die 5 for keeping the discharge amount of the raw material constant.
A first electric motor (rotary driving device for gear pump) 7 for rotating the gear pump 6 and a second electric motor (rotary driving device for screw) 8 for rotating the screw 3, and melting in the barrel 4 on the inlet side of the gear pump 6. A control device 10 having a pressure detector 9 for detecting the pressure of the raw material and controlling the amount of the raw material extruded from the die 5 is provided.

The control device 10 sets target values of the rotation speed (rotation speed) of the gear pump 6, the rotation speed (rotation speed) of the screw 3, and the pressure on the inlet side of the molten material of the gear pump 6 (hereinafter referred to as the inlet pressure). A target value setting unit 11, a low-pass filter (filter unit) 12 that receives a detected pressure (also an inlet pressure) from the pressure detector 9 and removes noise, and a detected pressure (a pressure that has passed through the low-pass filter 12). Hereinafter, the detected pressure that has passed through the low-pass filter is also referred to as the detected pressure from the pressure detector) and controls the rotation speed of the first electric motor 7 for the gear pump. A screw control unit 14 for controlling the rotation speed of the second motor 8 for screws by inputting the detected pressure from the Flip and, together may change the target values, and a control operation switching unit 15 for switching the control operation in each of the control sections 13 and 14.

As shown in FIG. 2, the gear pump control unit 13 outputs the target rotation speed from the target value setting unit 11 as a control value to the drive control unit 7a of the first electric motor 7 for the gear pump. The target value output path unit 21 and the detected pressure from the pressure detector 9 are input, and a command rotation speed is created based on the detected pressure.
A first command value output path section 22 for outputting to the drive control section 7a of the electric motor 7;

The first command value output path section 22 is provided with a differentiator (differential leading operation section) 31 for inputting the detected pressure from the pressure detector 9 and performing a differential leading operation, and a differential provided with an amplifier 32 thereof. A side path unit 33, a proportional unit (proportional leading operation unit) 34 for inputting a detected pressure from the pressure detector 9 and performing a proportional leading operation, and a proportional unit 34 provided in parallel with the proportional unit 34 to determine a target pressure and a detected pressure. A proportional integrator (proportional integral operation unit) 35 for performing a proportional integral operation by inputting the deviation, and outputting one of the output from the proportional unit 34 and the output from the proportional integrator 35 to the output from the differential side path unit 33 It is composed of a proportional path section 37 provided with a control changer (control change section) 36 for subtraction.

The drive of the first motor 7 for the gear pump is used as a control value, which is either the target rotation speed from the first target value output path section 21 or the command rotation speed from the first command value output path section 22. A control switch (control switching unit) 38 for outputting to the control unit 7a is provided.

Each of the target values [N _g ] is set in the middle of the set value output paths 23 and 24 from the target value setting section 11 to the first target value output path section 21 and the first command value output path section 22. (Rotational speed), P _s (pressure)] and amplifiers 25 and 26 that output target values (r · N _g , r · P _s ) by multiplying them by a preset operation ratio r.

As shown in FIG. 3, the screw control unit 14 uses the target rotation speed from the target value setting unit 11 as a control value as the control value of the second drive control unit 8 of the second motor 8 for screw.
and a second target value output path section 41 for outputting the detected pressure from the pressure detector 9 and, based on the detected pressure, create a commanded number of revolutions, and as a control value, a second drive control section of the second electric motor 8. 8a output to second command value output path section 42
It is composed of

Further, the second command value output path section 42
A differentiator (differential leading operation section) 51 which performs a differential leading operation by inputting a detected pressure from the pressure detector 9 and its amplifier 5
2 and a target value setting unit 1
The deviation between the target value from 1 and the detected pressure from the pressure detector 9 is input to a proportional unit (proportional operation unit) 54 and an integrator (integral operation unit) 55 arranged in parallel with the proportional device 54. And a proportional-integral path section 56 for adding the output to the output from the differential-side path section 53.

Further, either the target value from the second target value output path section 41 or the output from the second command value output path section 42 is output to the drive control section 8a of the second motor 8 for screws. Control switch (control switching unit) for control
57 are provided.

Further, similarly to the gear pump control unit 13 side,
A set value output path section 43 from the target value setting section 11 to the second target value output path section 41 and the second command value output path section 42;
In the middle of step 44, each target value [N _s (rotational speed), P _s (pressure)] is multiplied by a preset operation ratio r, and the target value (r
. N _s , r · P _s ) are provided, respectively.

Further, the second electric motor 8 for screw is provided with a current detector 8b, and the detected current from the current detector 8b is inputted to the control operation switch 15 so that the operation of the extruder 1 is controlled. Used when stopped.

Here, the target value set by the target value setting section 11 will be described. When the operation of the extruder 1 is started, the target values of the number of revolutions of the gear pump 6, the inlet pressure of the gear pump 6, and the number of revolutions of the screw 3 are set in a plurality of stages, for example, in order to simplify the explanation, FIG. ), The description will be made assuming that it changes in three steps. In this case, the first-stage step value a activates the control changer 36 of the gear pump control unit 13, the second-stage step value b activates the first control switch 38, and the third-stage step value c Is shifted to steady operation.

When the operation is stopped, FIG.
As shown in (2), it is assumed that it is changed stepwise in two stages. In this case, at the first step value d, the control changer 36 is operated, and at this step value, a raw material discharge waiting step is performed in which the raw material is discharged. When the current value of the second motor falls below a predetermined value,
The processing shifts to the second step value e where each target value becomes zero.

The transition between the step values in each of the target values is performed at a constant rate of change. By the way, each target value set by the target value setting unit 11 can be set freely. The target values of the rotation speed and the inlet pressure (detected pressure) output to the gear pump control unit 13 and the screw control unit 14 are set as common target values, which are basic target values, so that the settings can be easily performed. The target step value and the change rate are configured to be obtained by multiplying each by a unique coefficient, that is, an operation ratio r.

Next, a description will be given of control at the time of start-up with the above-described three-step values set. First, at the start of operation, the gear pump 6 is rotated at a low speed, for example, at a rotation speed of about one rotation per minute.

In this state, the resin raw material is supplied from the raw material supply hopper 2 into the barrel 4 and the operation of the screw 3 is started, and the respective target values from the target setting unit 11 are transmitted to the gear pump control unit 13 and the screw control unit. The control is performed by inputting the information to the control unit 14.

That is, in the screw control section 14, the second control switch 57 is connected to the second target value output path section 41 side, and the open loop control is performed based on the target rotation speed from the target setting section 11. Have been done.

Immediately after the start of operation, the first control switch 38 in the gear pump control unit 13 is connected to the first command value output path unit 22 side, and the control changer 36 is connected to the proportional unit 34 side. Therefore, the sum of the output of the differential pressure leading operation and the output of the proportional leading operation of the detected pressure is output to the drive control unit 7a of the gear pump 6 as a control value.

Thereafter, the target inlet pressure, the target rotation speed of the screw 3 and the target rotation speed of the gear pump 6 each increase at a constant rate toward the step value of the first stage. By this operation, the screw 3 rotation speed gradually increases from zero, and the molten raw material moves to the gear pump 6 in the barrel 4. Although the target inlet pressure also increases, the rotation speed control of the gear pump 6 is not a normal control that feeds back a deviation between the target inlet pressure and the inlet pressure that is the detected pressure, but is a proportional control as described above. Since the advance control is adopted, the change in the target inlet pressure does not affect the rotation speed control of the gear pump 6. That is, since the integration operation is not performed, the entrance pressure is prevented from entering the danger zone.

More specifically, a pressure deviation occurs until the raw material is filled, and when the integration operation is performed in this state, the operation of the integration operation is dominant and the gear pump is operated. Due to the slow rise of the rotational speed, the inlet pressure rises sharply at the time of filling. This is prevented.

When the step value of the first stage is reached, this step value is maintained, and the process waits until the molten raw material is filled in the barrel 4 and reaches the gear pump 6. When the barrel 4 is filled with the molten raw material, the inlet pressure of the gear pump 6 increases, and the rotation speed of the gear pump 6 is controlled so as to reduce the fluctuation.

That is, after the rotation speed increases, the moving average value of the inlet pressure becomes a predetermined value (for example, the step value of the first stage).
Then, the control operation switching unit 15 determines that the molten raw material is full, and connects the control changer 36 to the proportional integrator 35 to change to the differential leading PID control.

In this state, the inlet pressure becomes equal to the first value of the target value.
Wait for stabilization at the step value of the first step. It should be noted that if the inlet pressure changes within a certain range within a predetermined time, it is determined that the change is stable.

When the first step value is stabilized, the control operation switching unit 15 changes each target value to the second step value, that is, the inlet pressure is changed from the screw speed control to the inlet pressure feedback control. Change to the step value to be changed.

If it is determined that the inlet pressure is stabilized at the second step value for changing to the inlet pressure feedback control, the screw control is changed to the differential leading PID control and the gear pump control is changed. Is changed to open loop control based on the target rotation speed from the target setting unit 11.

That is, the second control switch 57 in the screw control section 14 is connected to the second command value output path section 42 side, and the detected pressure from the pressure detector 9 is input to the differentiator 51 to perform the differential leading operation. , And the output from the proportional unit 54 and the output from the integrator 55 are added to the difference between the target inlet pressure and the detected pressure, and the feedback control is performed.

The first in the gear pump control unit 13
The control switch 38 is connected to the first target value output path unit 21 side, and the rotation speed of the gear pump 6 is subjected to open loop control based on the target rotation speed from the target value setting unit 11.

When each target value is stabilized at this step value, the control operation switching section 15 shifts to the step value in the third stage of steady operation. Then, when the inlet pressure is stabilized at the step value at the time of the steady operation, the steady operation is started.

During the steady operation, the gear pump 6
The open loop control based on the target rotational speed from the target setting unit 11 is performed for the rotational speed of the screw 3, and the feedback control based on the inlet pressure is performed for the rotational speed of the screw 3.

Next, control when the operation of the extruder is stopped (during gradual stop operation) will be described. At the time of this operation stop, as described above, a description will be given assuming that the stop is performed at two step values.

When the operation is stopped, the rotational speed of the gear pump 6 is determined by the differential leading P by the inlet pressure feedback control.
The ID-type control is performed, and the open-loop control is performed on the rotation speed of the screw 3.

That is, in the gear pump control section 13, the first control switch 38 is connected to the first command value output path section 22 side, and the control changer 36 is connected to the proportional integrator 35.
The difference between the target inlet pressure and the detected pressure is input to the proportional integrator 34 as an output from the differentiator 31, and the command value obtained by subtracting the output obtained by performing the proportional integration is subtracted. Is output to the rotation control unit 7a of the gear pump 6 as a control value.

In the screw control unit 14,
The second control switch 57 is connected to the second target value output path section 41, and the target rotation speed is controlled by the rotation control section 8a of the screw 3.
Is input to

By this control change, each target value in the target setting section 11 is changed from the target step value at the time of steady operation to the step value of waiting for the second-stage raw material discharge when the operation is stopped.

When the inlet pressure is stabilized at this step value, the integration operation is stopped in controlling the rotation speed of the gear pump 6. That is, the control change 36 in the gear pump control unit 13 is connected to the proportional device 34 side.

The reason why the integration operation is stopped is as follows.
This is to prevent an undesired increase in the rotational speed of the gear pump 6 because the inlet pressure may drop naturally due to a decrease in the amount of the molten material in the barrel 4 due to the stoppage of the supply of the raw material during the standby of the raw material discharge.

In this state, the molten raw material is discharged. The state of discharge of the molten raw material is determined by the control operation switch 15 based on a current value detected by a current detector 8b provided in the second motor 8 for screws. That is, as the amount of the molten raw material in the barrel 4 decreases, the load on the motor decreases, so that the current value decreases. When the predetermined current value is reached, it is determined that the molten raw material has been sufficiently discharged, and each target value is shifted to the second step value that finally becomes zero, and the extruder 1 is stopped.

As described above, the gear pump control unit and the screw control unit switch between the open loop control based on the target value and the feedback control based on the inlet pressure, respectively. Since the operation can be changed, the screw can be rotated at a predetermined rotation speed at the start of operation, and the operation of the integration operation becomes dominant when the material is filled, so that the inlet side pressure is reduced. Can be suppressed from rising.
That is, the operation at the time of starting can be performed automatically, safely and quickly.

Further, when the operation is stopped, the rotational speed of the screw is reduced, and the control of the gear pump is changed from the differential leading operation based on the inlet pressure and the proportional integral operation to the differential leading operation and the proportional leading operation. Therefore, it is possible to safely and quickly shift from the steady operation to the stopped state.

Further, since the target value is not a function of time, changing the step value of each target value at the time of starting and stopping the operation does not require extra time, that is, quickly starts the operation. From normal operation to normal operation, and from normal operation to operation stop. Therefore, at the time of operation start and operation stop in operation stop, consumption of useless raw materials which are not commercialized can be minimized.

Incidentally, in the above embodiment, the target value set by the target value setting section, particularly, the time at which the operation is started is set to three times.
Although the description has been given as the step value of the step, the number of steps may be two or more steps, and may be, for example, four steps.

At the first step value, the control of the gear pump is changed (proportional leading → proportional integration).
At the second step value, the screw speed control is switched from open loop control to feedback control and the gear pump speed control is switched from feedback control to open loop control. In the above, after the control is changed, the rotation speed control of the gear pump may be switched from the feedback control to the open loop control while the inlet pressure is stabilized.

FIG. 5 is a graph showing the states of the gear pump, the control speed of the screw, and the inlet pressure from the start of operation to the steady operation in the actual machine. in this case,
The target step of the rotation speed of the gear pump is set to four steps, and the control value of the gear pump is changed (proportional leading → proportional integration) at the step value of the first step, and the screw speed control is fed back from the open loop control. Control (FB) and control of the rotation speed of the gear pump are switched from feedback control to open loop control.

FIG. 6 shows the rotational speeds of the gear pump and the screw from the time of steady operation to the time of stoppage of operation of the actual machine.
The graph shows the state of the inlet pressure and the current state of the screw motor. In this case, the target step of the screw rotation speed is set to three stages, the rotation speed is once reduced by the step value of the first stage, and the feedback control of the gear pump is changed (proportional) by the step value of the second stage. Integration →
When the current value of the screw motor becomes equal to or less than a predetermined value (shown by a broken line), the rotation speed of the screw is controlled to zero.

[0069]

As described above, according to the control apparatus and the control method of the extruder of the present invention, the target values of the screw and the gear pump are changed and the control operation is switched based on the state of the pressure on the inlet side of the gear pump. Therefore, when the operation is started and when the operation is stopped, stable operation can be performed even if there is a transient fluctuation in the inlet pressure.

The gear pump control section and the screw control section each switch between open loop control based on the target value and feedback control based on the inlet pressure, and the gear pump control section changes the proportional preceding operation and the proportional integration operation. It is possible to rotate the screw at a predetermined rotation speed, for example, at the start of operation,
When the raw material is filled, the function of the integration operation becomes dominant and the rise of the inlet pressure can be suppressed. That is, the operation at the time of starting can be performed automatically, safely and quickly.

Further, when the operation is stopped, the rotational speed of the screw is reduced, and the control of the gear pump is changed from the differential leading operation based on the inlet pressure and the proportional integral operation to the differential leading operation and the proportional leading operation. Therefore, it is possible to safely and quickly shift from the steady operation to the stopped state.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a control device of an extruder in an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a schematic configuration of a gear pump control unit in the control device.

FIG. 3 is a block diagram illustrating a schematic configuration of a screw control unit in the control device.

FIG. 4 is a graph showing an outline of a target value in the control device.

FIG. 5 is a graph showing a target value, a control value, an inlet pressure, and the like when the operation is started when the control device is applied to an actual machine.

FIG. 6 is a graph showing a target value, a control value, an inlet pressure and the like when the operation is stopped when the control device is applied to an actual machine.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 extruder 3 screw 4 barrel 5 die 6 gear pump 7 first motor 8 second motor 9 pressure detector 10 control device 11 target setting unit 12 low-pass filter 13 gear pump control unit 14 screw control unit 15 control operation switching unit 21 first Target value output path section 22 First command value output path section 31 Differentiator 33 Differentiating path section 34 Proportional unit 35 Proportional integrator 36 Control changer 37 Proportional side path section 38 First control switch 41 Second target value output path Unit 42 second command value output path unit 51 differentiator 53 differentiating path unit 54 proportional unit 55 integrator 56 proportional integration path unit 57 second control switch

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kiyoshi Imada 1-7-89 Minami Kohoku, Suminoe-ku, Osaka-shi, Osaka Inside Hitachi Zosen Corporation (72) Inventor Sakuhiro Sakane 1 Minami-Kohoku, Suminoe-ku, Osaka-shi, Osaka No.7-89 F-term in Hitachi Zosen Corporation (reference) 4F207 AP03 AR09 AR14 AR15 KA01 KL94 KM04 KM05 KM14 KM15

Claims (8)

[Claims] 1. A cylindrical casing in which a screw for kneading a raw material is disposed, a die for guiding the raw material kneaded and melted in the cylindrical casing into a predetermined thickness and width, and A gear pump arranged between the casing and the die to maintain the discharge amount of the raw material constant, a screw rotary drive for rotating the screw and a gear pump rotary drive for rotating the gear pump,
A control device for an extruder, comprising: a pressure detector that detects an inlet pressure of the gear pump; a target value setting that sets a target value of a rotational speed of the gear pump, a rotational speed of a screw, and a target value of an inlet pressure of the gear pump. A gear pump control unit for inputting a detected pressure from the pressure detector to control the rotation speed of the rotary drive for the gear pump; and a rotary drive for the screw receiving the detected pressure from the pressure detector. A screw control unit that controls the rotation speed of the control unit, and a control operation switching unit that can change each target value according to the detected pressure input from the detection pressure device and that switches a control operation in each control unit. The target value set by the target value setting unit has a plurality of step values, and shifts between the step values and switches control operations. The control device of the extruder, characterized by being configured to perform, based on the detected pressure. 2. A cylindrical casing in which a screw for kneading a raw material is disposed, a die for guiding the raw material kneaded and melted in the cylindrical casing to a predetermined thickness and width, and A gear pump arranged between the casing and the die to maintain the discharge amount of the raw material constant, a screw rotary drive for rotating the screw and a gear pump rotary drive for rotating the gear pump,
A control device for an extruder, comprising: a pressure detector that detects an inlet pressure of the gear pump; a target value setting that sets a target value of a rotational speed of the gear pump, a rotational speed of a screw, and a target value of an inlet pressure of the gear pump. A gear pump control unit for inputting a detected pressure from the pressure detector to control the rotation speed of the rotary drive for the gear pump; and a rotary drive for the screw receiving the detected pressure from the pressure detector. A screw control unit that controls the rotation speed of the control unit, and a control operation switching unit that can change each target value according to the detected pressure input from the detection pressure device and that switches a control operation in each control unit. A first target value output path unit that outputs the gear pump control unit to the gear pump rotary drive machine using the target rotation speed from the target value setting unit as a control value; A first command value output path section for inputting a detected pressure from the pressure detector, generating a commanded rotational speed based on the detected pressure, and outputting the commanded rotational speed as a control value to a gear pump rotary drive machine; The output path section includes a differential leading operation section that performs a differential leading operation by inputting a detected pressure, a proportional leading operation section that performs a proportional leading operation by inputting a detected pressure, and a target provided in parallel with the proportional leading operation section. A proportional integration unit that performs a proportional integration operation by inputting a deviation between the pressure and the detected pressure; and subtracts one of the output from the proportional leading operation unit and the output from the proportional integration unit to the output from the differentiation operation unit. A control change unit, and using either the target rotation speed from the first target value output path unit or the command rotation speed from the first command value output path unit as a control value, Controller of the extrusion molding machine according to claim 1, characterized in that a first control switching unit for outputting the motive. 3. A second target value output path for outputting the target rotation speed from the target value setting unit to the screw rotation drive unit as a control value, and a pressure detected by the pressure detector. And a second command value output path section for generating a command rotational speed based on the detected pressure and outputting the command rotational speed as a control value to the screw rotary drive machine. The second command value output path section receives the detected pressure. A differential leading operation unit for performing a differential leading operation, and a proportional integration operating unit for inputting a deviation between the target pressure and the detected pressure, performing a proportional integration operation, and subtracting the output from the differential operating unit, and A second control switching unit that outputs, as a control value, either the target rotation speed from the second target value output unit or the command rotation speed from the second command value output unit to the screw rotation drive unit. Controller of the extrusion molding machine according to claim 2, symptoms. 4. A control change step value for changing a control from a proportional leading operation to a proportional integral operation to each target value at the time of starting operation set by a target value setting section, and a target rotational speed of a screw. 4. The extrusion method according to claim 2, further comprising a control switching step value for switching from control based on the pressure on the inlet side to control based on the pressure on the inlet side and switching from control based on the pressure on the inlet side of the gear pump to control based on the target rotation speed. Control device for molding machine. 5. A method according to claim 1, wherein at least the target value set at the time of operation stop at the target value setting section is controlled by controlling at least the gear pump rotation speed from the differential leading operation based on the inlet pressure and the proportional integral operation to the inlet pressure. A control change step value for changing the control to the differential leading operation and the proportional leading operation based on the screw is provided. When the current value of the screw rotary driving machine falls below a predetermined value, The control device for an extruder according to any one of claims 2 to 4, wherein the rotation is stopped. 6. A cylindrical casing in which a screw for kneading a raw material is arranged, a die for guiding the raw material kneaded and melted in the cylindrical casing to form a predetermined thickness and width, and A gear pump arranged between the casing and the die to maintain the discharge amount of the raw material constant, a screw rotary drive for rotating the screw and a gear pump rotary drive for rotating the gear pump,
A pressure detector for detecting an inlet-side pressure of the gear pump, wherein at the time of starting operation, while controlling the rotation speed of the screw based on a target value from a target value setting unit, When the inlet pressure reaches a predetermined value, the rotational speed of the gear pump is controlled by a differential leading operation based on the inlet pressure and a proportional leading operation. When the inlet pressure reaches the control switching step value, the screw rotation speed is switched to control based on the inlet pressure, and the gear pump rotation speed is controlled. Is a method for controlling an extruder, wherein the control is switched to a control based on a target rotation speed. 7. A cylindrical casing in which a screw for kneading the raw material is disposed, a die for guiding the raw material kneaded and melted in the cylindrical casing to form a predetermined thickness and width, and A gear pump arranged between the casing and the die to maintain the discharge amount of the raw material constant, a screw rotary drive for rotating the screw and a gear pump rotary drive for rotating the gear pump,
A method for controlling an extruder having a pressure detector for detecting an inlet-side pressure of the gear pump, wherein when the operation is stopped, the rotation speed of the screw is controlled based on a target rotation speed from a target value setting unit. At the same time, the rotational speed of the gear pump is controlled by a differential leading operation based on the inlet pressure and a proportional integral operation based on the deviation between the target pressure and the inlet pressure. A control method for an extruder, wherein a rotational speed is controlled based on a differential leading operation based on an inlet pressure and a proportional leading operation. 8. After the inlet-side pressure has stabilized to the raw material discharge waiting step value, the current value in the screw rotary drive machine is:
The control method for an extruder according to claim 7, wherein the target values of the screw, the gear pump, and the inlet pressure are shifted to zero when the predetermined value becomes equal to or less than a predetermined value.