JPS5835444B2 - Method and device for controlling resin temperature in a kneader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for controlling the temperature of molten resin in a mixer, and in particular, a method for controlling the temperature of molten resin to a constant level when kneading thermoplastic synthetic resin. Namihi has a passion for equipment.

It is well known that a kneading machine is provided with a conical constriction between the cylinder and the screw, and the degree of kneading of the thermoplastic synthetic resin is changed by moving this conical conical constriction back and forth to adjust the size of the gap. It is well known that in such a kneading machine, the cylinder temperature is automatically adjusted using a conventionally known electric or pneumatic temperature adjusting device, and the width of the gap between the conical constrictions is adjusted to make the crosstalk effect mainly dependent on the shear rate. The present inventor had previously proposed that this be done using internal heat generated by the rotation of the screw.

However, in the former method, which automatically adjusts the cylinder temperature, the response from when a temperature correction signal is given to when the temperature of the molten resin changes is slow, and the wasted time is large, resulting in overshoot and undershoot. Couldn't adjust properly.

The latter method, which adjusts the internal heat generation, that is, the gap width of the conical part, makes it relatively easy to change the desired resin temperature. This has been done by setting a manual device that includes manual backpressure adjustment.

However, it is difficult to maintain the resin temperature constant due to disturbances such as fluctuations in the type of raw resin, screw rotation speed, and cylinder temperature, so manual setting of the gap width is repeated through trial and error to achieve the desired resin temperature. Although the gap width was adjusted, the response time was slow, so I had to rely on my experience and intuition for the relationship between temperature and gap width.

In view of these points, the present invention provides a kneading machine that has a conical constriction section between the cylinder and the screw, and adjusts the size of the gap between the conical constriction sections to change the degree of kneading of the synthetic resin. , which is used in a two-screw continuous kneading machine as described in Japanese Patent Publication No. 47-42583, samples the deviation between the set temperature and the actual temperature, and accumulates this sampling value at regular intervals as a temperature correction signal. This signal is added to the set gap signal, and this added signal is used as an on/off signal to correct the gap in stages using a screw moving device, thereby preventing incorrect position control and incorrect position control in the event of an abnormal occurrence due to temporary fluctuations in crosstalk during control. This prevents long-term temperature fluctuations caused by repetition and allows molten resin to be kept at a constant temperature.

That is, the present invention provides a kneading machine that has a conical constriction between a cylinder and a screw, and changes the degree of kneading of synthetic resin by adjusting the size of the gap between the conical constriction. A step of sampling the deviation from the temperature, a step of accumulating the sampled values in the sampling step at regular intervals, and adding the accumulated value from the accumulating step to the set gap signal as a temperature correction signal. By providing the step of correcting the gap by giving the addition signal as an on/off signal to the screw moving device in stages, it is possible to repeat the incorrect position control and the incorrect position control when detecting an abnormality due to temporary fluctuations in the crosstalk state during control. This is a resin temperature control method in a crosstalk machine, which is characterized by preventing long-period temperature fluctuations caused by the molten resin and scaling the molten resin at a constant temperature.

The present invention also provides a kneading machine that has a conical constriction between the cylinder and the screw and changes the degree of kneading of the synthetic resin by adjusting the gap size of the conical constriction. A resin temperature detector for detecting, a screw moving device for changing the gap of the conical constriction part, a position detector for detecting the position of the gap, and setting the temperature of the molten resin to predict the gap of the conical constriction part in advance. and a temperature control device, and the temperature control device further includes a deviation detection unit that detects a temperature deviation between the set temperature and the operating temperature, and a sampling device that accumulates the deviation temperature at regular time intervals. an adjusting section; an adding section that matches the pre-estimated setting gap signal with the temperature correction signal from the sampling adjusting section; and a feedback unit that compares the instruction signal from the adding section with the measured gap signal from the position detector. This is a resin temperature control device for a kneading machine, characterized by comprising: an adjustment section, and an on/off adjustment section that operates the screw moving device using a gap correction signal from the feedback adjustment section.

To explain the present invention with respect to the apparatus according to the illustrated embodiment, FIG. 1 shows a schematic configuration diagram of the main parts, and FIG. 2 shows a circuit system diagram.

First, in Figure 1, 1 is the cylinder of the crosstalk machine, 2 is the screw,
la and 2a are conical constrictions formed on the secondary cylinder 1 and screw 2, respectively, and 3 is the conical conical constriction. This is the gap between a and 2a.

Further, numeral 4 is a resin temperature detector inserted into the internal space of the cylinder 1 to detect the measured temperature of the molten resin, and 5 is a screw moving device for changing the gap 3 by changing the position of the screw, which has a hydraulic construction.

6 is also a position detector for the moving position of the screw, that is, the position of the gap 3;
7 is a temperature control device.

8 is a temperature setting device that takes out the set temperature, and 8 is a gap setting device that takes out the setting gap.

Therefore, the set temperature and set gap are the two-stage regulator 8. &' is pre-calculated and its output is input into the temperature adjustment device 7, and the actual measured temperature from the resin temperature detector 4 and the actual measured gap width from the position detector 6 are inserted into the temperature adjustment device 7. The output of 7 adjusts the screw moving device 5 as a gap correction signal.

Furthermore, a circuit diagram showing the contents of the temperature control device 7 is shown in FIG.

In FIG. 2, the temperature adjustment device 7 includes a deviation detection section 9, a sampling adjustment section 10, an addition section 11, a feedback adjustment section 12,
This is an on/off controller 13, and an automatic control switch 14 is inserted between the sampling controller 10 and the adder 110. The resin temperature detector 4 has a temperature indicator 15, and the position detector 6 has a gap indicator 16. Provided as necessary.

Further, the temperature setting device 8 is outputted to a deviation detection section 9, the gap setting device is outputted to an addition section 11, and the position detector 6 is outputted to a feedback adjustment device 12, respectively.

Next, the operation of the device of the present invention will be explained.

To plasticize the thermoplastic synthetic resin, the screw is rotated at high speed and the synthetic resin is fed from the inlet of the cylinder 1 to the feed section of the screw.

The synthetic resin supplied to the supply section of the screw 2 is sent forward by the supply section of the screw and passes through the gap 3 between the conical sections 1a and 2a of the screw 2 under great pressure.

At this time, large shearing forces and frictional forces act on the synthetic resin, causing the synthetic resin to generate internal heat and rapidly become plasticized.

The synthetic resin plasticized in this way is extruded by the extrusion section of the screw 2.

During this time, in the deviation detection section 9, the actual measured temperature at the tip of the screw is detected by the resin temperature detector 4, and the deviation from the desired temperature set in advance by the temperature setting device 8 is detected.

Moreover, this measured temperature can also be indicated externally by attaching a temperature indicator 15 if necessary.

In the sampling adjustment section 10, this temperature deviation is
Sampling is performed at preset fixed time intervals.

In addition, this sampled temperature deviation may occur immediately after operation or when the difference between the set temperature and the actual measured temperature is large.
It is best to sample only the range where temperature control is possible, with a certain temperature difference during normal operation, without sampling.

This sample value is accumulated into a temperature correction signal.

Due to this sample value accumulation adjustment, offset of the temperature control device 7 can be prevented.

Next, the adder 11 adds the signal from the set gap and the temperature correction signal, which were predicted in advance with the gap setting device, and sends the added signal to the on/off controller 13, which turns the gap correction on and off in stages. A signal is given to the screw moving device 5.

The ratio at which the temperature correction signal is added to the signal from the set gap in the adder 11 is adjusted by ratio adjustment.

By adjusting the ratio, the ratio of gap position adjustment and temperature adjustment can be adjusted according to the operating conditions.

Further, this addition signal is subjected to feedback control by a feedback adjustment section 12 at an actual gap measured by the position detector 6.

The on/off adjustment section 13 stabilizes the on/off signal for gap correction by making the adjustment set point and dead zone variable.

If continuous control is used, when the temperature is low, a temperature increase signal is issued continuously, the constriction portion is further constricted, and the resin temperature gradually increases.

However, since the wasted time is large, the temperature reaches the set value after the throttling that raises the resin temperature to the maximum is reached, but since the throttling reaches the maximum resin temperature, the resin temperature rises rapidly and greatly exceeds the set value.

Next, on the contrary, the constricted portion opens, causing a reciprocating phenomenon in which the resin temperature drops too much, and also has the disadvantage that the temperature range becomes large.

In order to improve the above drawbacks, sampling control and on/off control are performed by a sampling adjustment section as in the present application.

If an on/off adjustment section is incorporated, the temperature gradient will become gentler and the temperature curve will eventually fall within the upper and lower limits of the set value.

Further, by providing the automatic control switch 14 between the sampling adjustment section 10 and the addition section 110, it is possible to perform position control only by feedback control of the set gap of the gap 3 and the measured gap without adding the actually measured temperature of the molten resin to the control. Become.

According to the present temperature control device 7, overshoot and undershoot in control are prevented by performing cumulative sampling adjustment and giving control output to the load in stages for dead time dominated processes with slow control response. ,
We were able to provide critical damping to the process system.

By making the ratio between the set gap signal and the temperature correction signal variable, efficient, quick and accurate temperature control suitable for the process system is possible.

It is also possible to perform temperature-related control (only a constant gap).

We were able to break away from conventional controls that had many errors, such as constant gap, constant back pressure, and constant cylinder temperature.

[Brief explanation of the drawing]

FIG. 1 is a temperature control system diagram according to an embodiment of the present invention, and FIG. 2 is a circuit configuration diagram of the temperature control device in FIG. 1. In the figure, 1 is a cylinder, 2 is a screw, la and 2a are conical throttle parts, 3 is a gap between the throttle parts, 4 is a resin temperature detector, 5 is a screw moving device, 6 is a position detector, 7 is a temperature adjustment device,
8 is a temperature setting device, G is a gap setting device, 9 is a deviation detection section, 1
0 is a sampling adjustment section, 11 is an addition section, 12 is a feedback adjustment section, and 13 is an on/off adjustment section.

Claims (1)

[Claims] 1. A kneading machine that has a conical constriction between a cylinder and a screw, and that changes the degree of kneading of synthetic resin by adjusting the size of the gap between the conical constriction. A step of sampling the deviation between the temperature and the measured temperature, a step of accumulating the sampled values in the sampling step at regular intervals, and adding the accumulated value from the accumulating step to the set gap signal as a temperature correction signal. and a step of correcting the gap by giving the added signal as an on/off signal to the screw moving device in stages, thereby preventing incorrect positioning control and incorrect positioning due to abnormality detection due to temporary fluctuations in crosstalk during control. A resin temperature adjustment method in a kneading machine that prevents long-term temperature fluctuations due to repeated control and scales molten resin at a constant temperature. 2. In a kneader that has a conical constriction between the cylinder and the screw, and adjusts the gap size of the conical constriction to change the degree of kneading of the synthetic resin, the actual temperature of the molten resin is detected. a screw moving device for changing the gap between the conical constrictions, a position detector for detecting the position of the gap, and a temperature detector for setting the temperature of the molten resin to predict the gap between the conical constrictions in advance. Each setting device is comprised of a temperature control device, and the temperature control device further includes a deviation detection unit that detects a temperature deviation between the set temperature and the operating temperature, and a sampling control unit that accumulates the deviation temperature at regular intervals. a feedback unit that compares the instruction signal from the addition unit with the measured gap signal from the position detector. an adjustment section;
A resin temperature control device in a crosstalk machine, comprising an on/off control section that operates the screw moving device using a gap correction signal from the feedback control section. 3. A patent that provides an automatic control switch on the input side that feeds the output of the sampling adjustment section to the addition section, making it possible to control the position only by feedback control of the gap without adding the actually measured temperature of the molten resin to the control. A resin temperature control device in a kneading machine according to claim 2.