JPH05228982A - Controlling device for resin temperature inextruder - Google Patents

Abstract

PURPOSE:To provide a resin temperature controlling device in an extruder wherein temperature of discharging resin can be kept in a set temperature by eliminating influence of temperature change of a cylinder. CONSTITUTION:Among a plurality of cylinder temperature control zones C1-C5 a set temperature at a control loop of a zone nearest to a cylinder outlet 11 whose temperature change influences the most a discharging resin temperature is controlled in a cascading manner such that a set value of the discharging resin temperature is detected and corrected based on a difference between the set value and an actual temperature, so that a discharging resin temperature control loop can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control device in an extruder, and more particularly to a resin temperature control device for keeping a discharged resin temperature constant.

[0002]

2. Description of the Related Art FIG. 7 shows a structure of a resin temperature control device 10 in a conventional extruder. In the figure, a pellet-shaped plastic material 9 is supplied from the hopper 3 into the cylinder 5 and is forwarded by the screw 7 while being externally heated by a heater (for example, H1, H2, ..., H5) and the friction of the material itself. It is melted by the internal heat generated by the shearing action, and melted from the cylinder outlet 11 to the molten resin 13
Is extruded as. The cylinder 5 is divided into a plurality of temperature control zones (for example, C1, C2, ..., C5) in the longitudinal direction, and a heater (H1, H) is provided for each temperature control zone.
2, ..., H5), a cooling device (not shown), temperature setting units 151 to 155, temperature sensors (T1, T) such as thermocouples.
2, ..., T5), temperature controllers 171 to 175, and temperature sensors such as thermocouples (T) are set so that the temperature is set by the temperature setting sections 151 to 155 for each temperature control zone.
1, T2, ..., T5), the temperature of each temperature control zone is detected, the difference between the set temperature and the detected temperature is obtained by the adders 191-195, and heating or cooling is performed based on the temperature difference. Feedback control is being performed.
The temperature of the discharged resin is usually controlled by adjusting the set temperature of each temperature control zone, but the optimum setting of the temperature of each temperature control zone depends on the resin and screw used, or the operating conditions. It took time because it required skill and required trial and error. In order to solve this problem, several methods have been proposed in which the temperature of the molten resin at the cylinder outlet is directly detected and the temperature of the temperature control zone is controlled based on that value. For example, as described in Japanese Patent Application Laid-Open No. 49-11952, the temperature of a heater that is provided at the tip of the cylinder of an extruder is controlled to form a temperature control loop that differs depending on whether the extruder is operating or not operating. Control methods have been proposed. That is, according to this temperature control method, a temperature control loop is formed by the temperature value of the resin extruded during the operation of the extruder, and a temperature control loop is formed by the temperature detected at the tip of the cylinder during the rest of the extruder. ing. Also, JP-A-63-104
Japanese Patent No. 814 discloses a control device in which the temperature detected by a temperature detector of an arbitrarily selected cylinder control block is used as a control amount of a resin temperature control loop for controlling the resin temperature.

[0003]

However, JP-A-49-49
In the temperature control method described in Japanese Patent No. 11952, although the cylinder part is provided with a plurality of heaters,
Since the temperature control loop is formed only for the heater at the tip of the cylinder outlet, the temperature control loop for other heaters is formed rather than for the heater at the tip of the cylinder outlet depending on the structure and characteristics of each extruder. In some cases, it is more preferable, and there is a problem of lacking versatility. Further, in the control device disclosed in JP-A-63-104814,
Since the values are different in each heating zone inserted in parallel, it is difficult to determine the control parameters for highly accurate and stable control. Further, it is difficult to decide how to optimally control the temperature deviation of the extruded resin to each loop because it depends on the type of the extruder, the resin used and the operating conditions. Furthermore, since the temperature of the heating zone included in this parallel loop is passively determined by the control characteristics of the resin temperature control loop,
There is a problem that the temperature profile may not be preferably set. Further, in the case of any of the above references, since the discharge resin temperature is not affected and is fed back to each related zone, for example, even if a disturbance or the like is applied to a zone other than the temperature zone included in the resin temperature control loop. However, there is a problem that the discharge resin temperature changes because it takes time for the effect to be detected by the discharge resin temperature sensor and fed back to each heating zone.

The present invention has been made to solve the above problems, and it is necessary to control the temperature of the molten resin at the cylinder exit of the extruder stably, with high responsiveness, and for this control. It is an object of the present invention to provide a resin temperature control device for an extruder, which enables easy adjustment of various parameters.

[0005]

In order to achieve the above object, the resin temperature control device for an extruder according to the present invention divides the cylinder portion of the extruder into a plurality of temperature control zones along the length direction, Extruded in a temperature control device of an extruder that includes a temperature setting unit that sets a target temperature in each temperature control zone, a heater, and a cylinder temperature detection unit, and that controls the temperature in each temperature control zone. The resin temperature setting unit that sets the target temperature of the resin, the resin temperature detection unit that detects the temperature of the extruded resin, and the set temperature of the temperature control zone closest to the resin outlet of the plurality of temperature control zones. , Based on the difference between the target temperature set by the resin temperature setting unit and the resin temperature detected by the resin temperature detection unit,
A resin temperature compensating unit that performs a calculation for correcting only the amount that affects the resin temperature difference, and the set temperature of the temperature control zone closest to the resin outlet of the plurality of temperature control zones is set to the plurality of temperature control zones. Of the temperature control zone excluding the temperature control zone closest to the resin outlet of the above, based on the difference between the temperature detected in each zone and the cylinder detected temperature in each zone, to compensate for the influence of those temperature differences. And an influence amount compensating section for each temperature control zone for performing the calculation of, and the set temperature of the temperature control zone closest to the resin outlet of the plurality of temperature control zones from the resin temperature compensating section. It is characterized in that it is corrected by the output and the output from the influence compensator for each temperature control zone.

[0006]

In the resin temperature control device for the extruder according to the present invention, among the plurality of cylinder temperature control zones, the set temperature in the control loop of the zone closest to the cylinder outlet whose temperature change most affects the discharged resin temperature. Is detected by a set value of the discharge resin temperature and is corrected by a difference between the detected temperature and the actual temperature, so that the discharge resin temperature control loop is controlled. For the zones other than the temperature control zone closest to the cylinder outlet, the operation amount of the temperature control loop is cascade-connected to the discharge resin temperature control loop for the zone whose temperature change affects the discharge resin temperature. By doing so, it is possible to quickly cancel the temperature change caused by the temperature change of the zones other than the zone included in the discharge resin temperature control loop and the temperature change caused by the fluctuation of the screw rotation speed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a resin temperature control device in the extruder of the present invention. In the figure, the parts designated by the same reference numerals as those in FIG. 7 represent the parts having the same function. Reference numeral 21 is a resin temperature command unit for designating and outputting the temperature of the resin 13 extruded from the cylinder outlet 11,
Reference numeral 23 is a resin temperature detection unit that detects the temperature of the extruded resin 13, 25 is an adder that calculates and outputs the difference between the temperature commanded by the resin temperature command unit and the temperature detected by the resin temperature detection unit 23, and 27 Is the cylinder outlet 1 based on the difference between the set resin temperature input from the adder 25 and the detected resin temperature.
This is a resin temperature compensating unit that obtains a compensation amount for compensating the set temperature of the temperature control zone closest to 1 so that the difference between the set resin temperature and the detected resin temperature becomes zero. 291 ~
The reference numeral 294 indicates the setting of each temperature control zone in order to eliminate the influence of the temperature variation of the cylinder in the temperature control zone other than the temperature control zone C5 closest to the cylinder outlet 11 on the resin temperature detected by the resin temperature detection unit 23. It is an influence compensator that calculates a compensation amount based on the difference between the temperature and the detected temperature. 31 is obtained by adding the compensation amount obtained by the resin temperature compensating unit 27 and each compensation amount obtained by the influence compensating units 291 to 294, and adding the set temperature for the temperature control zone C5 closest to the cylinder outlet 11. It is an adder that compensates only the value.
Note that the compensation by the influence compensators 291 to 294 is not performed when the temperature set value of the temperature control zone is changed.

FIG. 2 shows a block diagram of the device shown in FIG. G1 (Z) to G5 (Z) represent the transfer functions of the heating and cooling systems in each temperature control zone of the cylinder, and Gr1 (Z) to Gr5 (Z) represent the transfer effect of each barrel temperature on the resin temperature. Is a function. Bc
1 (Z) to Bc5 (Z) are transfer functions of temperature controllers 171 to 175 that control the temperature of the cylinder, and perform PID control. The temperature control zone C5 at the final stage of the cylinder is used to keep the resin temperature at the set value. Temperature controller 17
The resin temperature is controlled by changing the set value of the cylinder temperature of 5 (Bc5 (Z)) by the resin temperature compensating unit 27 (transfer function Kr (Z)). Here, a value obtained by subtracting the detected resin temperature value from the set value of the resin temperature passes through the resin temperature compensating unit 27 (transfer function Kr (Z)) and the temperature controller 17
5 (Bc5 (Z)) and two paths for giving the set value of the resin temperature to the temperature controller 175 (Bc5 (Z)). By doing so, the feedback gain of the resin temperature compensator 27 (transfer function Kr (Z)) can be significantly reduced, and the resin temperature compensator 27 (transfer function Kr
Since the presence of (Z) has almost no effect on the stability of the entire loop, the trouble of tuning can be reduced. Although the structure of Bc5 (Z) of the temperature controller 175 performs PID control, it may have only an integral element. Further, Bc5 (Z) of the temperature controller 175 may be tuned for normal cylinder temperature control. A thermocouple or the like is used as the resin temperature sensor used in the resin temperature detection unit 23, but since it contacts the molten resin to detect the temperature,
Often destroyed. Further, the resin is not filled in the cylinder before the molding, and in that case, the resin temperature sensor does not detect the resin temperature. In this device, in order to prevent the cylinder from being overheated and cooled when the resin temperature is not correctly detected in this way, the upper and lower limits of the changing range of the cylinder set temperature are ± 20 ° C with respect to the resin temperature set value. Is set to. The transfer functions K1 (Z) to K4 (Z) are calculated by the influence compensators 291 to 294.
Is a compensating element for removing the influence of the temperature fluctuation of the temperature control zone of each cylinder on the resin temperature. For example, K4 (Z) is a compensating element for removing the influence of the temperature variation of the temperature control zone C4 on the resin temperature. If there is variation in the temperature control zone C4, the set temperature of the temperature control zone C5 is changed. The influence of the temperature fluctuation of C4 on the resin temperature is removed to keep the resin temperature constant. These compensation elements are not activated when the set temperature is changed. The reason for this is that, when operated at the time of changing the setting, the outputs from the respective compensation elements K1 (Z) to K4 (Z) are added together, and the fluctuation of the set temperature of the temperature control zone C5 becomes too large, resulting in an excessive response. Is. In order to prevent these compensating elements from operating at the time of changing the setting, the operation is stopped when the setting is changed, and the operation is restarted when the moving average of the cylinder temperature falls within several degrees of the set temperature. The compensation elements K1 (Z) to K4 (Z) are composed of proportional, differential or proportional elements only. This is because if there is an integral element, the temperature deviation of the cylinder is always integrated, which is not preferable.

FIG. 3 shows the temperature of the temperature control zone C4 when the temperature control zone C4 and the set value of the resin temperature are changed by 10 ° C. from the middle when the temperature control of the extruder of the present invention is performed. FIG. 9 is a graph showing a state of temporal changes in temperature of the temperature control zone C5 and resin temperature.
It can be seen that the set temperature of the temperature control zone C5 is changed to match the resin temperature in order to follow the set value, and the resin temperature is made to match the set value. FIG. 4 shows a temperature control zone C4 in the temperature control device of the extruder shown in FIG.
And the temperature control zone C5 by changing the set temperature by 10 ° C., respectively, showing the state of the temporal change of the resin temperature and the temperature of each zone. The resin temperature changes in such a state that the temperature change in the temperature control zone C5 becomes dull. FIG. 5 shows zones C4 and C5 when the heating of the temperature control zone C4 is stopped from the time indicated by the arrow in the resin temperature control device of the extruder of the present invention and the state of changes in the resin temperature. When the heating of the zone C4 is stopped, the set temperature of the zone C5 changes, and it can be seen that the fluctuation of the resin temperature is reduced and the set temperature is maintained. FIG. 6 shows the temperature control device for the extruder shown in FIG. 7, in the same manner as in the case of FIG. 5, from the time indicated by the arrow in the figure to the temperature control zone C.
4 shows the state of changes in zones C4 and C5 and the resin temperature when heating of No. 4 is stopped. In this case, it is understood that the resin temperature gradually decreases as the temperature of the temperature control zone C4 decreases.

[0010]

As described above, according to the resin temperature control device of the extruder of the present invention, the temperature of the extruded resin can be kept constant, and the influence of the temperature fluctuation of the cylinder on the resin temperature can be reduced. You can

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a resin temperature control device for an extruder showing an embodiment of the present invention.

FIG. 2 is a control block diagram of a resin temperature control device for an extruder according to the present invention.

FIG. 3 is a diagram showing a state of a resin temperature and a temperature change of a cylinder portion when a resin temperature control device for an extruder of the present invention is used.

FIG. 4 is a diagram showing a state of a resin temperature and a temperature change of a cylinder portion in the case of using a conventional temperature control device for an extruder under the same conditions as in FIG. 3;

FIG. 5 is a diagram showing a state of a resin temperature change and a temperature change of a cylinder portion when the resin temperature control device for the extruder of the present invention is used.

FIG. 6 is a diagram showing a state of a resin temperature and a temperature change of a cylinder portion in the case of using a conventional temperature control device for an extruder under the same conditions as in FIG. 4;

FIG. 7 is a diagram showing a configuration of a conventional temperature control device for an extruder.

[Explanation of symbols]

 C1 to C5 Temperature control zone H1 to H5 Heater 5 Cylinder 13 Discharge resin 151 to 154 Cylinder temperature setting part 171 to 175 Temperature controller 21 Resin temperature command part 23 Resin temperature detecting part 25 Adder 27 Workpiece 291 to 294 Influence part Compensator 31 Adder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayuki Yagi 3-2068 Ooka, Numazu City, Shizuoka Prefecture Numazu Works, Toshiba Machine Co., Ltd. In the office

Claims (3)

[Claims] 1. A cylinder part of an extruder is divided into a plurality of temperature control zones along a length direction, and a temperature setting part for setting a target temperature in each temperature control zone, a heater, and a cylinder. In an extruder temperature control device that includes a temperature detection unit and controls the temperature in each temperature control zone, a resin temperature setting unit that sets the target temperature of the extruded resin and the temperature of the extruded resin are detected. Resin temperature detection unit, the set temperature of the temperature control zone closest to the resin outlet of the plurality of temperature control zones, the target temperature set in the resin temperature setting unit and the resin temperature detected in the resin temperature detection unit Of the temperature control zone that is closest to the resin outlet of the plurality of temperature control zones, and performs the calculation for correcting only the amount that affects the resin temperature difference based on The temperature difference is based on the difference between each temperature set in the temperature control zone excluding the temperature control zone closest to the resin outlet of the plurality of temperature control zones and the cylinder detection temperature in each zone. , And an influence amount compensator for each temperature control zone that performs a calculation for correcting only the influence, and the set temperature of the temperature control zone closest to the resin outlet of the plurality of temperature control zones. Is corrected by the output from the resin temperature compensator and the output from the influence compensator for each temperature control zone. 2. The extruder according to claim 1, wherein the calculation performed by the resin temperature compensator and the influence compensator for each temperature control zone is a combination of proportional, integral and differential operations. Resin temperature control device. 3. According to the calculation result performed in the resin temperature compensating section and the influence compensating section for each temperature control zone,
The extruder according to claim 1, wherein the set temperature of the temperature control zone closest to the resin outlet of the plurality of temperature control zones is compensated after the resin temperature reaches a steady state. Resin temperature control device.