JPH0571023B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method and apparatus for controlling the temperature of an extrusion molding die used in a large-capacity granulator or the like that molds a resin material into granules. The present invention relates to a method and apparatus for controlling the temperature of an extrusion molding die heated by steam.

(Prior Art) Generally, resin materials are transported after kneading raw materials and processing them into granular pellets. Such resin pellets are manufactured by continuously extruding kneaded molten resin through a number of narrow nozzles provided in an extrusion molding die, and cutting the resin into small pieces with a rotating cutter. In this case, the cutting is often done in cooling water to prevent the formed pellets from welding together.

In a granulator that uses such an underwater cut method, the forming die comes into contact with cooling water, so while passing through the narrow nozzle of the forming die,
There is a risk that the molten resin will solidify. Therefore,
The molding die is provided with a heating jacket, and the nozzle portion is heated by flowing a heating medium such as steam or heating oil through the jacket.

In that case, since the heating temperature affects the properties of the resin, the heating temperature must be appropriately controlled. However, especially in the case of steam, it is difficult to directly control its temperature.

Conventionally, therefore, the heating temperature was controlled by adjusting the pressure of the steam supplied from the steam source to the extrusion molding die.

(Problems to be Solved by the Invention) However, in the case of steam, the relationship between pressure and temperature is not necessarily constant. For example, if the steam is overheated, lowering the pressure may not lower the temperature as expected. Therefore, simply setting the steam pressure is not enough.
Appropriate steam temperature cannot be obtained. for that,
When trying to adjust the steam temperature, it is necessary to adjust the steam pressure while checking the actual temperature of the molding die.

Moreover, in the case of an underwater cut type granulator,
Since the temperature load on the molding die changes with changes in the temperature of the cooling water used, changes in the amount of resin pellets produced, etc., it is necessary to perform such adjustment work frequently. Therefore, it is required that the work be made as simple as possible.

The present invention has been made in view of these problems, and its purpose is to uniquely control the temperature of steam by setting the pressure of steam.

Another object of the present invention is to provide a control device that can easily control the temperature of steam.

(Means for solving the problem) In order to achieve this object, the method of the present invention forcibly maintains the steam supplied to the extrusion molding die in a saturated state and adjusts the pressure. In this way, the desired steam temperature is obtained.

Further, an apparatus for carrying out the method includes a pressure regulating means capable of regulating the steam pressure and a loader capable of regulating the temperature load provided in the steam supply line, and a control means capable of controlling the pressure regulating means and the loader. It is characterized by having the following.
The control means controls the steam supplied to the extrusion molding die to be saturated steam at a predetermined pressure based on the relationship between the pressure and temperature of the saturated steam.

(Operation) For steam in a saturated state, the relationship between its pressure and temperature is uniquely determined. Therefore, by providing saturated steam to the extrusion die, the desired steam temperature can be obtained simply by setting the steam pressure.

Converting superheated steam to saturated steam can be easily achieved by adjusting the magnitude of the temperature load applied to the steam.

(Example) Hereinafter, an example of the present invention will be described using the drawings.

In the drawings, FIG. 1 is a system diagram showing an embodiment of the temperature control device for an extrusion molding die according to the present invention.

As is clear from this figure, the extruder cylinder 1
An extrusion die 3 having a large number of thin nozzles 2, 2, ... is attached to the tip of the cylinder 1, and the molten resin extruded from the cylinder 1 flows through the nozzles 2,
It is shaped into a strand by... A cutter case 4 is attached to the front surface (right side in the figure) of the molding die 3, and cooling water is circulated through the cutter case 4. Therefore, the strand-shaped molten resin extruded from the nozzles 2, 2, . . . is cooled and solidified within the cutter case 4. Then, the resin is cut into small pieces by a rotary cutter 5 that rotates near the front surface of the molding die 3.

In this way, a granulator for producing resin pellets is constructed.

A heating jacket 6 is installed on the peripheral wall of the extruder cylinder 1.
is provided, and the molten resin within the cylinder 1 is heated by the steam introduced into the jacket 6. In addition, the molding die 3
Also, a heating jacket 7 is provided to surround the nozzles 2, 2, . The jacket 7 receives steam supplied from a steam source 8 through a steam supply line 9 to the forming die 3.
It is designed to be guided from above. In this way, the molten resin passing through the nozzles 2, 2, . . . is heated and kept warm by the steam. The steam generated in the jacket 7 is drained from the bottom of the molding die 3 into a steam trap 1.
It is designed to be discharged through 0.

The steam supply line 9 is provided with a pressure regulating valve 11 that can adjust the pressure of steam, and a loader 12 that can apply a temperature load to the steam. The load device 12 is designed to cool the steam just before being supplied to the forming die 3 with cooling water, and the steam generated by the temperature load is drained through the steam trap 13 to the load device. It is designed to be discharged from 12.

The flow rate of the cooling water flowing through the load device 12 is regulated by the flow rate regulating valve 14, thereby controlling the flow rate of the cooling water flowing through the load device 1.
The magnitude of the temperature load at step 2 can be adjusted. That is, in this embodiment, the flow rate regulating valve 14 constitutes a load regulating means.

The pressure regulating valve 11, which is a pressure regulating means, and the flow regulating valve 14, which is a load regulating means, are operated by an arithmetic controller 15.
They are each controlled by

This arithmetic controller 15 is provided with a temperature setting device 16 for setting a desired temperature. A signal from this temperature setting device 16 is guided to a pressure controller 18 via a temperature converter 17 and also to a temperature controller 19. The temperature-pressure converter 17 calculates the pressure of the saturated steam at a set temperature based on a relational expression between the pressure of the saturated steam and the temperature. In the case of saturated steam, the relationship between pressure and temperature is constant, so the pressure corresponding to the set temperature is uniquely determined.

The pressure controller 18 of the arithmetic controller 15 receives the output from the pressure detector 20 that detects the pressure of the steam after being adjusted by the pressure regulating valve 11, that is, the pressure PT of the steam supplied to the molding die 3. A signal is being input. And this pressure controller 1
8, the required pressure determined by the temperature-pressure converter 17 and the pressure PT detected by the pressure detector 20 are compared, and the pressure regulating valve 11 is adjusted so that the actual steam pressure PT becomes the required pressure. The control signal is now output.

On the other hand, in the temperature controller 19 of the arithmetic controller 15,
An output signal from a temperature detector 21 that detects the temperature of the steam after passing through the load device 12, that is, the temperature TE of the steam immediately before being supplied to the molding die 3 is input. And this temperature controller 19
, the set temperature set in the temperature setting device 16 and the temperature TE detected by the temperature detector 21 are compared, and a signal is generated to control the flow rate regulating valve 14 so that the actual steam temperature TE approaches the set temperature. is now being output.

Next, the operation of the temperature control device configured as described above will be explained.

A steam source 8 supplies superheated steam.

Here, a desired temperature is set in the temperature setting device 16 of the arithmetic controller 15. Then, the set temperature is
In the temperature-pressure converter 17, the pressure is converted to the required pressure level. The pressure is the pressure at which steam in a saturated state reaches the set temperature. and,
The pressure thus determined by the pressure controller 18 and the pressure PT detected by the pressure detector 20
The pressure regulating valve 11 is controlled so that these are equal to each other. In this way, the pressure PT of the steam supplied to the molding die 3 becomes a pressure corresponding to the set temperature set in the temperature setting device 16.

The steam whose pressure is adjusted in this way is
It is then guided to the loader 12. In the load device 12, steam is cooled and condensed by applying a temperature load. The degree of condensation is
It is controlled by adjusting the amount of cooling water flowing through the load device 12 using a flow rate adjustment valve 14. In this way, the steam is made into saturated steam.

Whether the steam is kept saturated or not
The determination is made by comparing the actual steam temperature TE detected by the temperature detector 21 with the set temperature. In the case of saturated steam, the actual steam temperature TE should be equal to the set temperature by adjusting the pressure to correspond to the set temperature.
Therefore, when there is a difference in their temperatures,
Since it is considered that the steam is not in a saturated state, the amount of cooling water flowing through the load device 12 is adjusted by controlling the flow rate adjustment valve 14, and the magnitude of the temperature load is adjusted.

In this way, the steam supplied to the forming die 3 is forced to remain saturated. Therefore, the temperature can be controlled only by adjusting the pressure.

In this case, the flow control valve 14 which is the load adjustment means
is merely for adjusting the magnitude of the temperature load by the loader 12 and keeping the steam in a saturated state. Furthermore, the temperature controller 19 merely determines whether or not the steam is saturated. Therefore, the temperature of the steam is controlled solely by adjusting the steam pressure using the pressure regulating valve 11. That is, as long as the steam can be kept in a saturated state, such a flow rate control valve 14, temperature controller 19, etc. are unnecessary.

FIG. 2 is a system diagram showing another embodiment of the extrusion molding die temperature control device according to the present invention. In this embodiment, the only difference from the embodiment shown in FIG. 1 is the load adjustment mechanism of the loader, so corresponding parts are given the same reference numerals and redundant explanation will be omitted.

As shown in FIG. 2, in the case of this temperature control device, the loader 12 that applies a temperature load to the steam cools and condenses the steam using cooling air supplied from the cooling blower 22. has been done. The cooling blower 22 is controlled by the arithmetic controller 15
The operation is controlled by the output signal from the temperature controller 19, and the magnitude of the temperature load on the load device 12 is thereby adjusted. Therefore, in this embodiment, the cooling blower 22 constitutes a load adjusting means.

Also in the temperature control device configured in this way, the pressure of the superheated steam supplied from the steam source 8 is adjusted by the pressure regulating valve 11 to a level corresponding to the set temperature, and then the pressure is adjusted by the load device 12. It is said to be saturated steam. Therefore, the temperature of the steam introduced into the extrusion molding die 3 becomes the temperature of the saturated steam corresponding to the pressure adjusted by the pressure regulating valve 11, that is, the set temperature.
When the steam temperature differs from the set temperature, it means that the steam is not saturated, so the flow rate of cooling air flowing through the load device 12 is controlled by adjusting the rotation speed of the cooling blower 22, and the size of the temperature load is reduced. be adjusted.

In this way, the same effects as the embodiment shown in FIG. 1 can be obtained.

In addition, in the above embodiment, the extrusion molding die 3
Although only the temperature of the steam introduced into the jacket 7 of the cylinder 1 is controlled, the temperature of the steam introduced into the jacket 6 of the cylinder 1 can also be controlled in the same manner.

Further, the present invention can be applied not only to the extrusion molding die 3 of such a granulator, but also to temperature control of a molding die in other large-capacity extrusion molding machines.

(Effects of the Invention) As is clear from the above explanation, according to the present invention, the steam supplied to the extrusion molding die is kept in a saturated state while its pressure is controlled. As a result, the steam temperature can be uniquely determined, making it possible to easily and accurately control the steam temperature.

And whether the steam is saturated or not,
This can be easily determined by comparing the steam temperature with the set temperature, and the steam can be adjusted to a saturated state by adjusting the size of the temperature load applied to the steam. Therefore, it is also possible to automatically control the steam temperature.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment of the temperature control device for an extrusion molding die according to the present invention, and FIG.
FIG. 3 is a system diagram showing different embodiments of the temperature control device according to the present invention. 3...Extrusion molding die, 7...Heating jacket,
8... Steam source, 9... Steam supply line,
11...Pressure regulating valve (pressure regulating means), 12...
Load device, 14...Flow rate adjustment valve (load adjustment means),
15... Arithmetic controller (control means), 16... Temperature setting device, 17... Temperature pressure converter, 18... Pressure controller, 19... Temperature controller, 20... Pressure detector,
21... Temperature detector, 22... Cooling blower (load adjustment means).

Claims (1)

[Claims] 1. The pressure necessary to bring the saturated steam to a desired temperature is determined from the relationship between the pressure and temperature of the saturated steam, and the pressure of the steam supplied from the steam source to the extrusion molding die is determined by A method for controlling the temperature of an extrusion molding die, which comprises controlling the pressure so as to achieve a desired pressure, and adjusting the steam to a saturated state by applying a temperature load to the steam. 2. Determine whether or not the steam supplied to the extrusion molding die is in a saturated state by comparing the actual temperature of the steam with a desired temperature, and adjust the temperature so that the steam becomes saturated. The extrusion molding die temperature control method according to claim 1, characterized in that the magnitude of the load is adjusted. 3. A load device capable of applying a temperature load to the steam supplied from the steam source to the extrusion molding die, a load adjustment means capable of adjusting the magnitude of the temperature load by the load device, and a pressure adjustment device capable of adjusting the pressure of the steam. and control means for controlling the pressure adjusting means and the load adjusting means, respectively, based on the relationship between the pressure and temperature of the saturated steam so that the steam supplied to the extrusion molding die becomes saturated steam at a desired temperature. A temperature control device for an extrusion molding die, comprising: and. 4. The control means includes a temperature setting device that can set a desired steam temperature, and a temperature-pressure converter that can calculate the pressure of saturated steam corresponding to the set temperature, and the temperature-pressure converter The extruder according to claim 3, wherein a control signal corresponding to the calculated pressure is sent to the pressure adjusting means, and a control signal corresponding to the set temperature is sent to the load adjusting means. Molding die temperature control device. 5 The control means compares the actual temperature of the steam supplied to the extrusion molding die with the set temperature, and transmits a control signal to the load device to adjust the temperature load of the load device so that the difference therebetween becomes smaller. The extrusion molding die temperature control device according to claim 4, further comprising a temperature controller that sends the temperature to the regulating means.