JPH1177803A - Method and equipment for controlling extrusion in extruder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable stabilization of weight irrespective of the characteristics of a viscoelastic fluid or an environment of operation and thereby to improve a yield. SOLUTION: A detected value of a temperature sensor 118 is inputted to a first arithmetic part 124 and, based on the detected value of the temperature sensor 118 just before or just after the operation of an extruder 10 and on data stored in a first memory area 122A, a discharge amount variation curve at a start of the operation of the extruder 10 is preestimated and sent out to a second arithmetic part 126. In the second arithmetic part 126, a speed of rotation of a screw 108 corresponding to the detected temperature is computed on the basis of the preestimated discharge amount variation curve and data stored in a second memory area 122B and it is sent out to a drive control part 128. In this drive control part 128, the speed of rotation of the screw 108 is controlled on the basis of the detected temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extruder for conveying a viscoelastic fluid by rotating a screw and discharging the viscoelastic fluid from a die having a predetermined shape. The present invention relates to a method and an apparatus for controlling extrusion in an extruder.

[0002]

2. Description of the Related Art Conventionally, when a viscoelastic fluid, for example, rubber is extruded by an extruder, the extruder rotates a screw to convey the viscoelastic fluid to an extrusion port provided with a mouthpiece having a predetermined shape. At this time, the vicinity of the extrusion port in the extruder is pressurized and extruded according to the shape of the die.

[0003] The quality control of the extruded rubber is performed by stabilizing the weight. That is, the temperature of the rubber is raised by the above-described pressurization. By circulating the hot water, the temperature is maintained at a substantially constant temperature, and the rubber is extruded at a constant unit weight by rotating the screw at a constant speed. it can.

When the operation of the extruder is started, the pressure in the space near the extrusion port of the extruder is zero, and the rubber itself is also cooled, so that the stability of the weight is inferior to the steady state. , Causing the yield to deteriorate.

[0005] For this reason, conventionally, the stop time of the extruder has been set as a function. However, in the transition period from the steady state, the rotation speed of the screw and the draw-out conveyor disposed downstream of the extruder are controlled by preset control. To adjust the linear velocity.

That is, it is determined that the longer the stop time of the extruder, the more the rubber is cooled, and control is performed, for example, to rotate the screw faster than in a steady state.
As shown in FIG. 5, the rotational speed of the screw is gradually reduced in accordance with the time from the start of driving to return the screw to the steady state.

[0007]

However, in the control as shown in FIG. 5, linear deceleration is performed as the screw rotation time elapses. Due to variations in the working environment such as switching work, the correlation between the extruder stop time and the subsequent change in the discharge amount is not always linear, and sufficient weight stability may not be achieved.

In view of the above facts, the present invention provides an extrusion control method and apparatus for an extruder capable of improving weight stability and improving the yield, regardless of the characteristics of the viscoelastic fluid and the working environment. The goal is to obtain

[0009]

According to a first aspect of the present invention, there is provided an extruder for conveying a viscoelastic fluid by rotating a screw and discharging the viscoelastic fluid from a die having a predetermined shape. An extrusion control method in an extruder for controlling the amount of extrusion, wherein a temperature near the discharge port of the viscoelastic fluid of the die immediately after the start of extrusion or a parameter having a correlation with this temperature is measured, and the measured value is measured. Based on the temperature immediately after the start of extrusion and the steady temperature at which the initial temperature gradient and the discharge rate of the viscoelastic fluid are stable, the temperature rise gradient characteristic (characteristic 1) from at least the extrusion start temperature to the steady temperature is recognized, Recognizing the relationship between the discharge amount and the temperature in the vicinity of the discharge port (Characteristic 2) from Characteristic 1 and the relationship between the measured temperature of the viscoelastic fluid and the unit discharge amount of the screw, Based on the serial property 2, it is characterized by controlling the driving rotation speed of the screw.

According to the first aspect of the present invention, when the operation of the extruder is started, first, the temperature near the discharge port of the extruder is measured. It should be noted that other parameters having a correlation with this temperature, such as a pressure near the discharge in the extruder and a load current value caused by a load applied to the screw may be used. Hereinafter, description will be made on the assumption that the temperature is detected.

Based on the measured temperature immediately after (or immediately before) the start of extrusion and the steady temperature at which the initial temperature gradient and the discharge rate of the viscoelastic fluid are stable, the temperature from the extrusion start temperature to the steady temperature is determined. The temperature information gradient characteristic is recognized by calculation or the like (characteristic 1).

Since this property 1 differs depending on the physical properties of the applied viscoelastic fluid, it cannot be found simply from the initial temperature at the start of extrusion. Therefore, it is preferable to store in advance the steady-state temperature at which the initial temperature gradient and the discharge amount are stabilized for each physical property of the applicable viscoelastic fluid. However, in the present invention, the storage is not limited to the storage, and each time the operator inputs the information by key input or the like, or the LSI prepared for each viscoelastic fluid is used.
A card or the like may be inserted and read from this LSI card.

When the characteristic 1 is recognized, the relationship between the specific 1 and the relationship between the measured temperature of the viscoelastic fluid and the unit discharge amount of the screw is used to calculate the relationship between the discharge amount and the temperature in the vicinity of the discharge port. Recognize (characteristic 2). The relationship between the measured temperature of the viscoelastic fluid and the unit discharge amount of the screw may be stored in advance, or may be input by a key or a card.

When the characteristic 2 is obtained, the driving speed of the screw is controlled in the transitional period based on the characteristic 2 to change the properties of the applied viscoelastic fluid and the change in the working environment. The rotation speed of the screw can be controlled by the degree, and the stability of the weight can be maintained even in the transition period. Thereby, the yield can be improved.

According to a second aspect of the present invention, there is provided an extruder for conveying a viscoelastic fluid by rotating a screw and discharging the viscoelastic fluid from a mouthpiece having a predetermined shape. An extrusion control device in the extruder, wherein a temperature sensor for detecting a temperature in the vicinity of a discharge port of the viscoelastic fluid of the die is provided, and for each of the viscoelastic fluids, an initial temperature gradient and a discharge amount in the viscoelastic fluid are stable. First storage means for storing a steady temperature to be performed, and second storage for storing, for each of the viscoelastic fluids, a relationship between a temperature of the viscoelastic fluid detected by the temperature sensor and a unit discharge amount of the screw. Means, a temperature immediately after the start of extrusion detected by the temperature sensor, an initial temperature gradient and a steady temperature of the specific viscoelastic fluid stored in the first storage means, and a steady state from the extrusion start temperature. Temperature rise gradient characteristic prediction means for predicting a temperature rise gradient characteristic up to a temperature, a temperature rise gradient characteristic predicted by the temperature rise gradient characteristic prediction means, and a detected temperature-screw unit stored in the second storage means. A discharge amount characteristic, and a discharge amount prediction unit that predicts a relationship of a discharge amount to a temperature detected by the temperature sensor, and driving of the screw based on the prediction by the discharge amount prediction unit until the steady temperature is reached. Screw drive control means for controlling the number of revolutions.

According to the second aspect of the present invention, the first storage means previously stores, for each viscoelastic fluid, an initial temperature gradient in the viscoelastic fluid and a steady temperature at which the discharge amount is stabilized. The storage unit 2 stores, for each viscoelastic fluid, the relationship between the temperature of the viscoelastic fluid detected by the temperature sensor and the unit discharge amount of the screw.

The temperature sensor detects the temperature near the discharge port at the start of operation of the extruder (immediately or immediately after).

A temperature rise gradient is predicted based on the detected initial temperature and data stored in the first storage means (temperature rise gradient prediction means). Thereby, a different temperature rise gradient can be recognized for each applied viscoelastic fluid.

Next, the relationship between the temperature of the discharge port and the unit discharge amount of the screw is predicted based on the temperature rise gradient and the data stored in the second storage means (discharge amount prediction means).

Based on this prediction, the screw drive control means can determine the screw rotation speed corresponding to the temperature detected by the temperature sensor. By determining the number of rotations of the screw by such control during the transitional period, the drive control management optimal for the working environment and the applied viscoelastic fluid can be performed.

[0021]

FIG. 1 shows an extruder 100 according to the present embodiment and a control block diagram thereof.

The extruder 100 has a casing 102 having a cylindrical shape, and a rotary shaft 104 disposed inside the extruder 100 so as to coincide with the axis of the casing 102. Rotating shaft 10
A blade member 106 is attached in a spiral shape around 4, and constitutes a screw 108 as a whole.
The rotating shaft 104 is connected to a rotating shaft of a motor 110 provided on a base side of the casing 102 via a speed reducer (not shown). Therefore, when the motor 110 is driven,
The screw 108 rotates.

A material inlet 112 is provided on the peripheral surface of the casing 102 near the base side. In the present embodiment, rubber is injected as a viscoelastic fluid material. Here, the injected rubber is conveyed to the front end portion (the right end side in FIG. 1) of the casing 102 as the screw 108 rotates. The casing 1
02 is provided with a hot water flow path (not shown) to control the temperature of the rubber being conveyed.

At the tip of the casing 102, a base 11 is provided.
4 is attached. The base 114 is provided with a slit-shaped through-hole, and the rubber that has reached the distal end in the casing 102 is discharged so as to be pushed out from the slit-shaped through-hole.

Here, when the temperature of the rubber is constant and the rotation of the screw 108 is constant, the rubber discharged from the base 114 is discharged while maintaining the shape of the through hole. The discharged rubber is transferred to a drawer conveyor 116 disposed downstream of the extruder 100.

The drawer 116 is normally driven at a constant linear speed, and this linear speed matches the discharge speed of the rubber discharged from the extruder 100.

Here, the temperature of the rubber extruded from the extruder 100 is almost constant in a steady state as described above, and the unit weight of the extruded rubber is stable.
Immediately after the extruder 100 has stopped operating for a predetermined time, the temperature of the rubber is unstable (usually in a state of being cooled compared to an appropriate temperature).
And because the pressure inside the casing near the base is also small,
The discharge amount (discharge weight) becomes unstable.

Therefore, in the present embodiment, a temperature sensor 118 is provided near the base, and the speed of the screw 108 is controlled based on the temperature sensor 118 and parameters described later.

The temperature sensor 118 is connected to a controller 120 for controlling the extruder 100. The controller 120 is provided with a large-capacity memory 122, and the following characteristics are stored as a database.

The first database includes an initial temperature gradient for each viscoelastic fluid such as rubber applied to the extruder 100 of the present embodiment, that is, a change rate of the discharge amount with respect to the initial temperature, and a discharge steady temperature, that is, a discharge constant temperature. Is a temperature at which the ejection amount is stable, and is a predetermined area (first area) of the memory 122.
In the memory area 122A).

The second database stores the temperature at the start of extrusion for each viscoelastic fluid such as rubber applied to the extruder 100 of the present embodiment and the discharge amount per unit rotation of the screw (for example, one rotation). Relationship, a predetermined memory 1
22 is stored in another partial area (second memory area 122B).

The detected value of the temperature sensor 118 is input to a first arithmetic unit 124 in the controller 120. The first arithmetic unit 124 starts the operation of the extruder 100 based on the value detected by the temperature sensor 118 immediately before or immediately after the operation of the extruder 100 and the data stored in the first memory area 122A. The calculation for estimating the discharge amount variation curve at the time (see FIG. 2) is performed.

The predicted discharge amount fluctuation curve is obtained by the second
Is sent to the calculation unit 126. The second calculation unit 126 determines the rotation speed (see FIG. 3) of the screw 108 according to the detected temperature based on the predicted discharge amount variation curve and the data stored in the second memory area 122B. It is designed to calculate. This calculation result is sent to the drive control unit 128. The drive controller 128 receives a value detected by the temperature sensor 118. After the extruder 100 starts driving, a temperature image is periodically detected, and a screw is detected based on the detected temperature. 108
Is calculated, and the motor 110 is controlled.

The operation of this embodiment will be described below with reference to the flowchart of FIG. In step 150, it is determined whether or not the driving of the extruder 100 has been started. If the determination is affirmative, the process proceeds to step 152, where the initial temperature is detected using the temperature sensor 118.

Next, in step 154, data corresponding to the rubber applied this time is read from the first database (first memory area 122A), and then in step 156, the read data and the initial temperature are read out. Then, a prediction curve of the discharge amount is calculated (see FIG. 2).

In the next step 158, data corresponding to the rubber applied this time is read from the second database (second memory area 122B), and then in step 160, the read data and the prediction From the curve, a characteristic diagram (see FIG. 3) for determining the rotation speed of the screw 108 according to the detected temperature is calculated.

In the next step 162, the screw 10
The rotation of the drive 8 starts at a rotation speed based on the initial temperature. In the next step 164, the temperature is detected by the temperature sensor 118. Next, in step 166, the rotation speed of the screw 108 with respect to this temperature is determined from the characteristics of FIG. 3, and in step 168, the drive of the motor 110 is controlled.

In step 170, it is determined whether or not the stationary period has been entered. If the determination is negative, the process returns to step 164 to repeat the above steps. If a positive determination is made,
Thereafter, the rotation speed of the screw 108 is not controlled on the basis of the temperature, and in order to stabilize at a constant rotation speed, the process proceeds to step 172 to drive the motor 110 at a predetermined constant speed.

In the next step 174, it is determined whether or not the operation has been completed. If the determination is negative, the rubber extrusion operation at a constant speed is continued. If the determination is affirmative, the process proceeds to step 176. , Stop driving the motor 110,
The process ends.

As described above, the conventional method ignoring the physical properties of the rubber itself and the working environment in which the screw rotation speed until the steady state is linearly fluctuated, for example, linearly based on the temperature at the start of driving. As compared with the control, the discharge amount prediction curve is calculated each time, and the control is performed while detecting the temperature. Therefore, a stable discharge weight can be obtained even in a so-called transitional period, and the yield can be improved.

In the present embodiment, after the discharge amount prediction curve is determined and the relationship between the temperature and the rotation speed of the screw 108 is determined, the temperature sensor 1 is periodically operated during the transition period.
Although the rotation speed of the screw 108 was controlled while detecting the temperature at 18, since the time until the steady state can be recognized by obtaining the above data, the degree of change of the rotation speed of the screw 108 within this time is determined in advance. In addition, the rotation speed of the screw 108 may be changed by time control.

[0042]

As described above, the method and apparatus for controlling extrusion in the extruder according to the present invention can achieve weight stability and improve yield regardless of the characteristics of the viscoelastic fluid and the working environment. An extrusion control method and apparatus in an extruder that can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an extruder according to the present embodiment and a control block diagram thereof.

FIG. 2 is a discharge amount prediction characteristic diagram.

FIG. 3 is a temperature-screw rotation speed characteristic diagram.

FIG. 4 is a drive control flowchart of the extruder.

FIG. 5 is a characteristic diagram of a conventional screw rotational speed control.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 extruder 102 casing 104 rotating shaft 106 blade member 108 screw 110 motor 112 material input port 114 base 116 draw-out conveyor 118 temperature sensor 120 controller 122 memory 122A first memory area (first database) 122B second memory area ( (Second database) 124 first operation unit 126 second operation unit 128 drive control unit

Claims (2)

[Claims] An extruder for conveying a viscoelastic fluid by rotating a screw and discharging the viscoelastic fluid from a die having a predetermined shape. An extrusion control method in an extruder for controlling an extrusion amount of the viscoelastic fluid. The temperature near the discharge port of the viscoelastic fluid of the die immediately after the start of extrusion or a parameter having a correlation with this temperature is measured, and the measured temperature immediately after the start of extrusion and the initial temperature in the viscoelastic fluid are measured. Based on the temperature gradient and the steady temperature at which the discharge rate is stabilized, at least a temperature rising gradient characteristic (characteristic 1) from the extrusion start temperature to the steady temperature is recognized, and the characteristic 1, the measured temperature in the viscoelastic fluid, and the Based on the relationship with the unit discharge amount of the screw and the relationship between the discharge amount and the temperature in the vicinity of the discharge port (characteristic 2), the driving of the screw is determined based on the characteristic 2. Extrusion control method in an extruder which is characterized in that to control the rotational speed. 2. An extruder for conveying a viscoelastic fluid by rotating a screw and discharging the viscoelastic fluid from a die having a predetermined shape. And a temperature sensor for detecting a temperature in the vicinity of a discharge port of the viscoelastic fluid of the die, and for each of the viscoelastic fluids, a first temperature gradient in the viscoelastic fluid and a steady-state temperature at which a discharge amount is stabilized. A second storage unit that stores, for each of the viscoelastic fluids, a relationship between a temperature of the viscoelastic fluid detected by the temperature sensor and a unit discharge amount of the screw; From the detected temperature immediately after the start of extrusion and the initial temperature gradient and the steady temperature of the specific viscoelastic fluid stored in the first storage means, the temperature rise gradient from the extrusion start temperature to the steady temperature is obtained. And the temperature increase gradient characteristic estimating means for estimating a characteristic, the temperature increase gradient characteristic and temperature rise gradient characteristic predicted by the predicting means, the second detection temperature stored in the storage means -
Screw unit discharge amount characteristics, and discharge amount prediction means for predicting the relationship of the discharge amount to the temperature detected by the temperature sensor, until the steady temperature, until the steady-state temperature, the discharge amount prediction means based on the prediction, the screw An extrusion control device for an extruder, comprising: screw drive control means for controlling the number of drive rotations of the extruder.