JPH07156142A - Cooling method and its device of thermoplastic resin strand - Google Patents

Abstract

PURPOSE:To obtain a chip whose size is uniform, by a method wherein a plurality of positions are set up in a widthwise direction of a guide device allowing a strand extruded through a die head to stream down along with a cooling liquid, temperatures are measured at a plurality of downstream places of the positions each and flows of the cooling liquids at that positions are controlled based on a difference in the measured and set up temperatures. CONSTITUTION:A guide device 3 allowing a strand extruded through a die head 1 to stream down along with a cooling liquid is provided, for example, with three cooling liquid reserving parts 13 in a widthwise direction and, for example, four groups are provided in the downstream direction of the reserving part groups. A cooling fluid is supplied respectively to the reserving parts 13 each respectively through separate flow control valves 14 and the cooling liquid is streamed onto a fixed streaming chute 5 through upper outflow ports 16 each. Temperature sensors 19 are provided on the rears of the fixed chutes 5 positioning downstream of the outflow ports 16 each. Then in the case where the measured temperatures of the temperature sensors 19 each are higher than set up temperature ranges, the flow of the cooling liquid is increased and in the case where they are lower than the set up temperature ranges, the flow is reduced and the strand is cooled almost evenly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for cooling a thermoplastic resin strand, and more particularly to a method and an apparatus for transferring a molten thermoplastic resin strand while cooling and cutting it into chips. .

[0002]

2. Description of the Related Art When manufacturing chips, which are raw materials for thermoplastic resin products, for example, as shown in JP-A-4-69209, a molten state discharged from a reactor, an autoclave or an extruder is used. Thermoplastic resin, from a plurality of nozzles of the die head, extruded as a parallel strand group, with cooling water flowed out from the outlet, after cooling and solidifying while flowing down on the guide device,
In the cutting device, a rotary cutter is used to cut the chips while pulling them down with a nip roll.

By the way, in the above-mentioned conventional method, the temperature range of the strand at the time of extrusion from the die head and the temperature range at each position of the strand in the flow-down direction are set in advance, and the temperature range in the flow-down direction is set based on this set temperature range. The outflow amount of the cooling water from the plurality of outlets arranged is set.

However, in the above-mentioned prior art, when the actual temperature of the strand is out of the set temperature range, means for detecting this and adjusting the outflow amount of the cooling water from each outlet is provided. It wasn't done.

[0005]

Therefore, the strand is extruded from the die head at a temperature higher than expected, so that the temperature at each position in the downstream direction of the strand becomes equal to or higher than the preset temperature range or equal to or lower than the preset temperature range. In case of
There is a problem in that unevenness occurs in the cooling and solidification of the strands, the size and shape of the chips are not uniform, and the quality of the chips deteriorates.

It is an object of the present invention to provide a method for cooling a thermoplastic resin strand and an apparatus therefor capable of solving the above problems.

[0007]

In order to achieve the above object, the method for cooling a thermoplastic resin strand according to the present invention is characterized in that a strand made of a thermoplastic resin in a molten state is extruded from a die head and cooled. After cooling and solidifying while flowing down with the liquid on the guide device, in the method of cutting the strand into chips by the cutting device, in the guide device, a plurality of positions are set in the width direction, and a plurality of positions in the downflow direction are set. Measure the temperature at each point, and at the measurement point where the measurement temperature is higher than the set temperature range, increase the flow rate of the cooling liquid and at the measurement point where the measured temperature is lower than the set temperature range. The point is to reduce the amount of cooling liquid flowing down.

When the measured temperature is an abnormal temperature, the strand may be removed outside the guide device.

Further, the characteristic feature of the cooling device for the thermoplastic resin strand is that the strand made of the thermoplastic resin in a molten state is extruded from the die head and is made to flow down on the guide device together with the cooling liquid flowing out from the outlet. In the device for cutting the strands into chips by the cutting device after being cooled and solidified, a plurality of outlets are arranged in the width direction of the guide device to form an outlet group and the outlet group flows down. A plurality of temperature sensors are provided downstream of each outlet in the guide device.
The outflow amount of the cooling liquid from each outlet is increased when the temperature measured by the temperature sensor downstream of each outlet is higher than the set temperature range, and the measured temperature is lower than the set temperature range. In this case, a control means for reducing the number is provided.

In some cases, the upper part of the guide device may be provided with an excluding means for excluding the strand outside the guide device when the temperature measured by the temperature sensor is an abnormal temperature.

[0011]

The strand of molten thermoplastic resin is extruded from the die head, cooled and solidified while flowing down along with the cooling liquid over the guide device, and then cut into chips by the cutting device.

At this time, in the guide device, a plurality of positions are set in the width direction, and the temperature is measured at each of the plurality of positions in the downflow direction at each set position. Then, the flow rate of the cooling liquid is increased at the measurement point that is higher than the set temperature range, and the flow rate of the cooling liquid is decreased at the measurement point where the measurement temperature is lower than the set temperature range, and the measurement is performed. Control the temperature so that it is within the set temperature.

If the measured temperature is an abnormal temperature,
Exclude the strands outside the guiding device.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 and 2, reference numeral 1 denotes a die head, which is connected to a batch-type or continuous-type reactor, an autoclave, or an extruder which is not shown. The die head 1 is equipped with a large number of nozzles, for example, nozzles for 50 nozzles in two rows.
A molten strand group consisting of 00 thermoplastic resins is extruded.

Reference numeral 3 denotes a steeply-inclined guide device which causes the strand group extruded from the die head 1 to flow down together with the cooling liquid, and comprises a movable downflow chute 4 and a plurality of fixed downflow chutes 5.

The movable falling chute 4 constitutes the upper part of the guide device 3, is provided so as to be movable in the left and right direction by a pair of upper and lower guides 7, and is movable by a moving cylinder 8 as shown in FIG.
As shown by the solid line in Fig. 2, a guide position for guiding the strand group to the fixed downflow chute 5 and, as shown by the imaginary line in Fig. 2,
The strand group is displaced to the left from the guide position, and the position of the strand group can be freely changed to the exclusion position for removing the strand group to the collection container 9 below the guide position.

The fixed down-flow chutes 5 are four in the embodiment, are arranged in parallel in the down-flow direction, and have a groove shape composed of a bottom wall 10 and a pair of left and right side walls 11. In the vertically adjacent fixed downflow chutes 5, the upper end of the lower fixed downflow chute 5 is fitted to the lower end of the upper fixed downflow chute 5 from below.

In the guide device 3, as described below, four storage unit groups 13 each composed of three cooling liquid storage units 13 arranged side by side in the width direction are arranged side by side in the flow-down direction. That is, the storage portions 13 are formed in an opening shape in the front and are arranged side by side in the left-right direction on the back side of each fixed down-shoot chute 5, and the bottom wall thereof is the upper end portion of each fixed down-shoot chute 5. Bottom wall 1
It is fixed at 0. The top walls of the storage parts 13 other than the uppermost stage are fixed to the bottom wall 10 of the fixed downflow chute 5 adjacent to the upper side. The cooling liquid is supplied to each of the reservoirs 13 via the flow rate adjusting valve 14 which is separately provided.

In the guide device 3, as described below, four outflow port groups 16 each consisting of three outflow ports 16 arranged side by side in the width direction are arranged in the downflow direction. That is, the top walls of the three storage parts 13 arranged in parallel at the uppermost stage are slightly bent, and the space between each tip and the upper end of the fixed downflow chute 5 serves as an outlet 16. Further, the openings facing the ends of the vertically adjacent fixed downflow chutes 5 in each of the three storage sections 13 arranged side by side in the second row from the top are also referred to as outflow ports 16. In addition, in each of the third and fourth storage sections 13 from the top,
The outflow port 16 is formed in the same manner as described above. Then, the cooling liquid in each of the storage portions 13 gets over the upper end portion of the bottom wall 10 of the fixed downflow chute 5 and flows out from the outflow ports 16 onto the fixed downflow chute 5. In addition, each of the outlets 16 has a smaller opening area on the downstream side.

In addition, the guide device 3 is as follows.
Four temperature sensor groups, each consisting of three temperature sensors 19 arranged side by side in the width direction, are arranged in the downstream direction.
That is, three temperature sensors 19 located downstream of each outlet 16 are arranged in the width direction on the back surface of the central portion in the vertical direction of each fixed falling chute 5. A temperature measuring resistor, a thermocouple, a thermistor, or the like is used as the temperature sensor 19.

Reference numeral 21 denotes a cutting device for cutting the strand group that has flowed down the guide device 3 into chips. The housing 22, a pair of nip rolls 23 for pulling down the strand group, and the strands pulled down by both nip rolls 23. Fixed cutter 2 for cutting a group into chips
4 and the rotary cutter 25, and a servo motor (not shown) that rotationally drives the nip rolls 23 and the rotary cutter 25 separately. In addition, as shown in FIG.
Nozzle of die head 1 and nip roll 2 of cutting device 21
The fixed down-shooting chute 5 is less inclined than the dash-dotted line 26 connecting to the biting part 3 and the lower end of the bottom wall 10 of each fixed down-shoot chute 5 is almost in contact with the alternate long and short dash line 26. . Further, the carry-out chute 27 is integrally formed on the housing 22, and the housing 22 is
Is supplied with cooling liquid via a flow control valve 28 for chip transfer and additional cooling.

A control device 30 controls each flow rate adjusting valve 14 to increase the outflow amount of the cooling liquid from each of the outlets 16 toward the downstream side, and to control the amount of the cooling liquid from each of the outlets 16. The amount of outflow is measured by the temperature sensor 19 downstream of each outlet 16.
When the measured temperature is higher than the set temperature range, it is increased, and when the measured temperature is lower than the set temperature range, it is decreased. Further, when the temperature measured by the temperature sensor 19 is an abnormal temperature, the control device 30 operates the moving cylinder 8 to change the position of the movable downflow chute 4 to the exclusion position. The controller 30 also controls the flow rate adjusting valve 28.

According to the embodiment configured as described above, when manufacturing the chips of the thermoplastic resin, the cooling liquid (for example, cooling water or the like) is supplied to each cooling liquid storage portion 13 and the housing 22 of the cutting device. Is supplied to allow the cooling liquid to flow down on each fixed downflow chute 5, and the housing 22
And the cooling liquid is caused to flow into the carry-out chute 27.

In this state, the strand group made of the molten thermoplastic resin is extruded in parallel from the die head 1. At this time, the strand group in the initial stage of extrusion is often in a defective state.

Therefore, at the start of manufacturing, the movable falling chute 4 is set to the exclusion position as shown by the phantom line in FIG. 2, whereby the strand group extruded from the die head 1 is shown by the phantom line in FIG. As shown in the drawing, it flows down directly from the die head 1 and is discharged into the collection container 9 and does not flow down to the lower part of the guide device 3.

When the strand group extruded from the die head 1 is in a normal state, the moving cylinder 8
Thus, the movable falling chute 4 is moved to the guide position shown by the solid line in FIG. As a result, the strand group extruded from the die head 1 is guided by the movable downflow chute 4 to the fixed downflow chute 5 as shown by the alternate long and short dash line 26 in FIG. 1, while flowing down on the fixed downflow chute 5 together with the cooling liquid. After being cooled and solidified, it is pulled down by the nip roll 23 of the cutting device 21, cut into chips by the fixed cutter 24 and the rotary cutter 25, and carried out in the carry-out chute 27 together with the cooling liquid.

By the way, in the cutting device 21, since the strand group is cut while being pulled by the pair of nip rolls 23 as described above, the diameter of the strand becomes smaller as it gets closer to the cutting device 21, and the flow-down speed becomes higher. Becomes Therefore, if the flow-down speed of the cooling liquid is made to correspond to the increase in the flow-down speed of the strand and is not increased, the strand cannot be cooled and solidified uniformly in the flow-down direction, and unevenness occurs in the cooling and solidification of the strand, resulting in chip size and The shape cannot be made uniform, resulting in poor chip quality.

In view of this, in the embodiment, the opening area of each outlet 16 is made smaller toward the downstream side and each flow rate adjusting valve 14 is adjusted in response to the increase in the flow velocity of the strand on the guide device 3. By adjusting the flow rate, the flow rate of the cooling liquid from each of the outlets 16 is set to be higher on the downstream side. This allows
The strands can be cooled and solidified substantially uniformly in the downflow direction.

Further, when the temperature measured by one of the temperature sensors 19 becomes higher or lower than a preset temperature range due to the strand being extruded from the die head 1 at a higher temperature than expected. Is a flow control valve 1 connected to the outlet 16 upstream of the temperature sensor 19.
4 is immediately adjusted by the control device 30 to adjust the outflow amount of the cooling liquid from the outflow port 16. That is,
The outflow amount of the cooling liquid from the outlet 16 is increased when the temperature measured by the temperature sensor 19 is higher than the set temperature range, and when the measured temperature is lower than the set temperature range, Will be reduced. As a result, the degree of cooling of the strands is adjusted and the temperature measured by the temperature sensor 19 is controlled so as to be within the set temperature range, and the strands are cooled substantially uniformly in the downflow direction.

As described above, the strands can be cooled and solidified substantially uniformly in the flow-down direction, the size and shape of the chips can be made substantially uniform, and good quality of the chips can be maintained.

Further, the adjacent strands are fused and the strands are not cooled well, so that the temperature measured by each temperature sensor 19 becomes an abnormal temperature far out of the set temperature range. If the controller 3
In response to a command from 0, the moving cylinder 8 is actuated, the movable falling chute 4 is set to the exclusion position, and the defective strand group is excluded to the outside. Therefore, there is no fear that a large number of defective chips will be manufactured.

[0032]

As described in detail above, according to the present invention,
As the strand is extruded from the die head at a temperature higher than expected, the temperature measured at the predetermined position in the flow direction in the guide device is higher or lower than the set temperature range, and immediately the measured temperature is The strands are controlled to fall within the set temperature range, and the strands are cooled substantially uniformly in the downflow direction. Therefore, even in the above case, the size and shape of the chip can be made substantially uniform, and the quality of the chip can be maintained excellent.

Further, according to the second and fourth aspects, when the measured temperature becomes an abnormal temperature, the strand can be excluded to the outside of the guide device, and the possibility that a large number of defective chips will be manufactured can be eliminated. be able to.

[Brief description of drawings]

FIG. 1 is a vertical side sectional view showing an embodiment of the present invention.

FIG. 2 is a front development view showing an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Die head 3 Guide device 4 Movable downflow chute 5 Fixed downflow chute 8 Moving cylinder 13 Cooling liquid storage part 14 Flow rate adjusting valve 16 Outlet port 19 Temperature sensor 21 Cutting device 30 Control device

Claims (4)

[Claims] 1. A method in which a strand made of a molten thermoplastic resin is extruded from a die head, cooled and solidified while flowing down along with a cooling liquid on a guide device, and then the strand is cut into chips by a cutting device. In the device, a plurality of positions are set in the width direction, the temperature is measured at each of the plurality of positions in the downflow direction at each set position, and the measured temperature is higher than the set temperature range.
While increasing the flow rate of the cooling liquid, at the measurement point where the measurement temperature is lower than the set temperature range,
A method for cooling a thermoplastic resin strand, which comprises reducing the amount of cooling liquid flowing down. 2. The method for cooling a thermoplastic resin strand according to claim 1, wherein the strand is excluded outside the guide device when the measured temperature is an abnormal temperature. 3. A strand made of a thermoplastic resin in a molten state is extruded from a die head and cooled and solidified while flowing down on a guide device together with a cooling liquid flowing out from an outlet, and then the strand is cut into chips by a cutting device. In the cutting device, a plurality of outlets are arranged in the width direction of the guide device to form an outlet group, and a plurality of outlet groups are arranged in the downward direction. A temperature sensor is disposed downstream of each of the outlets to increase the outflow amount of the cooling liquid from each outlet when the temperature measured by the temperature sensor downstream of each outlet is higher than the set temperature range. At the same time, the cooling device for the thermoplastic resin strand is provided with a control means for reducing the measured temperature when the measured temperature is lower than the set temperature range. 4. The cooling device for a thermoplastic resin strand according to claim 3, wherein the guide device is provided with an excluding means for excluding the strand outside the guide device when the temperature measured by the temperature sensor is an abnormal temperature. .