JP2802786B2 - Blown film molding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blown film forming apparatus, and more particularly, to a forming apparatus having an air ring for adjusting a discharge amount of cooling air.

(Prior Art) In blown film forming processing for manufacturing a film or sheet from a thermoplastic resin material, it is necessary to keep a frost line of resin bubbles at a fixed position in order to obtain a high quality and constant quality of the formed film. However, the frost line is liable to fluctuate due to periodic or temporary fluctuations in molding processing conditions such as the temperature of the extruded molten resin and the temperature of the molding chamber.

Conventionally, in order to keep the frost line at a fixed position, a method has been adopted in which an operator exclusively adjusts the amount of cooling air discharged from the air ring manually. However, this adjustment is difficult even for a skilled worker, and it is not always possible to expect a constant frost line. Particularly when the operator has to adjust a plurality of molding devices, the difficulty is difficult. Was further increased.

Therefore, a method is known in which the diameter of the resin tube extruded from the die is detected by optical means, and the amount of compressed air press-fitted into the resin tube is automatically adjusted based on the detection signal.

(Problems to be Solved by the Invention) In such a method, the blow-up ratio of the resin tube is merely intended to be constant, and the frost line is adjusted in response to the fluctuation of various molding processing conditions. It was not always possible to meet the demand for keeping it constant.

It is also possible to detect the surface temperature of the resin tube and adjust the amount of cooling air in the air ring based on it.However, this is effective because the tube surface is exposed to the cooling air flow and there is a partial temperature difference. It is difficult to measure a proper temperature and cannot be adopted.

An object of the present invention is to solve the above problems and mechanically set the detector at a predetermined position in a tube expansion area that changes in accordance with a blow-up ratio set as a processing condition, and An object of the present invention is to provide an inflation film molding apparatus which automatically sets a frost line at a height position correspondingly determined and can mold a high-quality inflation tube to the market.

B. Configuration of the Invention (Means for Solving the Problems) In order to solve the above problems, the present invention is arranged at a predetermined position in a resin tube expansion region starting from an expansion start portion of a molten resin tube extruded from a die, and In an inflation film forming apparatus having a non-contact type for detecting the diameter of a resin tube at a position and an air ring for adjusting a discharge amount of cooling air by a signal from the detector, a direction parallel to a direction in which the tube is taken out. A support frame that can be moved up and down on the outside of the tube is provided on the machine frame of the molding apparatus so as to surround the tube. The support frame is connected to the lower end of the support frame and extends along the horizontal rail positioned outside the tube. The detector is provided on a slidable support bracket, and the drive sources of the support frame and the support bracket are combined. Characterized in that said detector to said position corresponding to the blow-up ratio of the resin tube are the so drive controllable to position adjustment.

The drive control device of the drive source includes a blow-up ratio setting unit, a calculating unit that calculates a moving amount of the support frame and the support bracket based on the selected blow-up ratio, and a calculating unit that calculates the moving amount based on the calculated moving amount. Means for driving each drive source.

An air ring cooling air discharge amount adjustment circuit is incorporated in the control device, and the cooling air discharge amount adjustment circuit uses an output signal of the detector and an output signal from the calculation unit as input signals.
The air ring discharge amount is adjusted.

The detector is provided on the support bracket with a pair of upper and lower pairs, and a signal for increasing the air flow of the air ring when the upper and lower pairs are turned on, and decreasing the air flow of the air ring when the two sets are turned off. It is preferable that the cooling air discharge adjusting circuit includes a drive control circuit that outputs a signal to the blower motor.

<Operation> The operation of the present invention configured as described above is as follows.

When the light emitted from the light emitter of the detector is partially scattered in contact with a predetermined point in the resin tube expansion area, and then reflected by the reflector, reaches the light receiver. Is discharged, but when the frost line rises due to a rise in the temperature of the molten resin supplied to the die or a rise in the temperature of the molding environment, the degree of expansion in the resin tube expansion region is reduced, or the resin tube expansion region rises. Therefore, the light from the light emitter enters the light receiver without coming into contact with the outer peripheral surface of the resin tube expansion area. Therefore, the amount of light received by the light receiver is increased, and the increase is transmitted to the control unit as an electric signal. The control unit adjusts the adjustment valve in a more open direction and increases the number of rotations of the blower, which increases the amount of cooling air from the air ring. It descends.

On the other hand, when the frost line is lowered due to a temperature drop of the molten resin, a temperature drop of the molding environment, or the like, the degree of expansion in the resin tube expansion region is increased, or the resin tube expansion region is lowered, and light from the light projector is emitted from the resin tube expansion region. The amount of light received by the light receiver is extremely reduced, and the decrease is transmitted as an electrical signal to the control unit, which adjusts the adjustment valve in a more closed direction and increases the rotation speed of the blower. As a result, the frost line rises because the amount of cooling air from the air ring is reduced.

Even if the temperature of the molten resin supplied to the die or the temperature of the molding environment changes periodically or temporarily, the frost line is always maintained at a fixed position corresponding to the set blow-up ratio. The Rukoto.

Next, when changing the blow-up ratio, first select the blow-up ratio to be changed, and based on the difference between the selected blow-up ratio and the blow-up ratio formed last time,
Calculating means calculates the amount of movement of the support frame and the support bracket. Based on the calculated value, each of the driving sources is driven, the support frame is raised and lowered as appropriate, and the support bracket is displaced along the horizontal rail, at a predetermined position in the expansion area corresponding to the selected blow-up ratio, Position this detector.

Thereafter, the molding is started with the blow-up ratio selected this time as in the previous time, and the frost line is automatically adjusted in the same manner.

(Example) Next, a typical example of the present invention will be described.

FIG. 1 shows the overall configuration of one embodiment of an inflation film forming apparatus according to the present invention.

In this figure, an extruder is connected to a die 1 having an annular extrusion lip, and a synthetic resin introduced from a hopper of the extruder is melted by the extruder and extruded from the die 1 into a resin tube 4 into a tube shape. Is done.

Compressed air is sealed in the resin tube 4, and the resin tube 4 is expanded in a resin tube expansion region starting from an expansion start portion A and reaching an expansion end portion B where expansion ends, and then a resin bubble is formed. 5 and is folded by the guide plate and the nip roll 7.

An air ring 8 is provided on the upper surface side of the die 1, and a blower 10 is connected to the air ring 8. By controlling the number of revolutions of the blower 10, the cooling air discharged from the air ring 8 is cooled. The amount can be adjusted. The resin tube 4 is forcibly cooled by the cooling air discharged from the air ring 8, and a frost line (not shown) is formed at a predetermined position of the bubble 5 above the resin tube expansion region.

Optical detectors 11a and 11b are provided in a pair at the predetermined position in the resin tube expansion region between the expansion start portion A and the expansion end portion B. Each of the detectors 11a and 11b includes a light emitter 12 and a light receiver 13, which are arranged on the same side as each other, and a reflecting plate 13a opposed thereto, and the light emitter 12 is disposed at a predetermined point on the outer peripheral surface of the resin tube expansion area. The light projected from the tangential direction is reflected by the reflector 13a and then projected to the light receiver 13, and the light receiver 13 includes a photoconductive cell, a photodiode, a phototransistor, a photoresistor, and the like. (See FIG. 3).

A guide rod 20 fixed to the machine frame 23 of the molding apparatus outside the tube 4 and parallel to the take-off direction of the tube 4
A support frame 22 which can be moved up and down along the axis is arranged so as to surround the tube 4, and can slide horizontally along a pair of horizontal rails 24a and 24b connected to the lower end of the support frame 22. Of the support brackets 25a and 25b, one of the support brackets 25a is provided with the light emitter 12 and the light receiver 13 of each of the detectors 11a and 11b, and the other support bracket 25b is provided with the reflector 13a (second). FIG. 3, FIG. 3).

The electric motors 26 and 27, which are the driving sources of the support frame 22 and the support brackets 25a and 25b, are provided with the detectors at the positions corresponding to the set blow-up ratio of the synthetic resin tube.
Drive control is possible to adjust the positioning of 11a and 11b.

Of the electric motors 26 and 27, the support brackets 25a and 25
The motor 27 for 5b is a linear motor, and the motor 26 for the support frame 22 forms a part of a winch for winding the suspension wire 28.

The drive control device 29 for the electric motors 26 and 27 includes a blow-up ratio setting unit 30 and a calculation unit 31 that calculates a movement amount of the support frame 22 and the support brackets 25a and 25b based on the selected blow-up ratio. A driver circuit 32 for driving the electric motors 26 and 27 based on the calculated movement amount.
Is provided.

Further, an air ring cooling air discharge amount adjusting circuit 33 is incorporated in the control device 29, and the cooling air discharge amount adjusting circuit 33 includes the detectors 11a and 11a.
The output signal 1b and the output signal from the calculating means 31, that is, the calculated value are used as input signals to adjust the rotation speed of the airing blower 10. More specifically, a signal for increasing the air volume of the air ring 8 when the detectors 11a and 11b are on and decreasing the air volume for the air ring when the detectors 11a and 11b are off is output to the motor 34 for the blower 10. The air discharge adjustment circuit 33 includes a drive control circuit 35.

If necessary, attach the bubble steady rest 37 to this support frame.
In some cases, it may be mounted horizontally extending from 22.

 The operation of this embodiment is as follows.

When the light emitted from the light emitter 12 having only the lower detector 11a is reflected by the reflector 13a without coming into contact with a predetermined point in the resin tube expansion areas A and B, and reaches the light receiver 13, the light is emitted from the air ring 8. Is discharging a certain amount of cooling air,
When the frost line rises due to a rise in the temperature of the molten resin supplied to the die 1 or a rise in the temperature of the molding environment, the degree of expansion in the resin tube expansion region is reduced, or the resin tube expansion region rises, and one set of upper and lower parts is detected. Container 11
The light from each of the projectors 12a and 11b enters the light receiver 13 after being reflected by the reflection plate 13a without coming into contact with the outer peripheral surface of the resin tube expansion area, so that the amount of light received by these light receivers 13 increases. The increase is transmitted to the drive control circuit 35 as an electric signal, and the drive control circuit 35 increases the rotation speed of the motor 34 for the blower 10, and as a result, the amount of cooling air from the air ring 8 increases. So the frost line goes down.

On the other hand, when the frost line is lowered due to a decrease in the temperature of the molten resin, a decrease in the temperature of the molding environment, or the like, the degree of expansion in the resin tube expansion regions A and B is increased, or the resin tube expansion region is lowered. 11
The light from each of the light projectors 12a and 11b is blocked by the resin tube expansion area, and the amount of light received by the light receiver 13 is extremely reduced.The decrease is transmitted to the drive control circuit 35 as an electric signal,
The drive control circuit 35 reduces the number of revolutions of the motor 34 of the blower 10, and as a result, the amount of cooling air from the air ring 8 decreases, so that the frost line rises.

In this way, even if the temperature of the molten resin supplied to the die 1 and the temperature of the molding environment fluctuate periodically or temporarily, the frost line is always maintained at a constant position.

Next, when changing the blow-up ratio, first, the blow-up ratio to be changed is selected by the setting means 30, and based on the difference between the selected blow-up ratio and the previously formed blow-up ratio, The calculating unit 31 calculates the amount of movement of the support frame 22 and the support brackets 25a and 25b. The drive motors 26 and 27 are driven based on the calculated value, and the support frame 22 is driven.
And the support brackets 25a, 25b are displaced along the horizontal rails 24a, 24b, and a set of upper and lower detectors 11a, 11b is placed at a predetermined position in the expansion area corresponding to the selected blow-up ratio. Position.

Thereafter, molding is started at the selected blow-up ratio as in the previous case, and the frost line F is automatically adjusted in the same manner.

C. Effects of the Invention In the present invention configured and operated as described above,
Since the position of the frost line is automatically fixed, it is not necessary for the operator to manually adjust the position, so that the workability is improved and labor is saved.

Further, unlike the case where the surface temperature of the resin tube expansion area is detected while being exposed to the cooling air flow, since the change in the diameter of the expansion area is captured to adjust the cooling air discharge amount of the air ring, the detection value Therefore, there is an effect that the response to the fluctuation factor of the frost line is sequentially and promptly and accurately performed. Therefore, extremely stable continuous molding, particularly high-speed continuous molding, can be stably performed.

In addition, the constant folding width of the molded film can be easily achieved, and a high-quality and constant-quality film having no unevenness in thickness and excellent in mechanical strength such as impact resistance can be molded.

Further, the detector can be automatically positioned at a predetermined position corresponding to various blow-up ratios, and the frost line can be adjusted quickly in response to a change in the blow-up ratio.

Note that the arrangement of the detectors is not limited to the above-described embodiment, and each of the light emitter 12 and the light receiver 13 is provided one by one so that a single light beam emitted by the light emitter reaches the light receiver 13. This is the same as the present invention.

[Brief description of the drawings]

FIG. 1 is a front view showing an entire configuration of an embodiment of an inflation molding apparatus according to the present invention, FIG. 2 is a partially omitted plan view showing a mounting portion of the detector, and FIG. 3 is a side view thereof. A: expansion start portion, B: expansion end portion, F: frost line, 1: die, 4: resin tube, 5: resin bubble, 8: air ring, 11: photoelectric detector, 12: Emitter, 13: Receiver.

Claims (4)

(57) [Claims] 1. A non-contact type detector which is disposed at a predetermined position in a resin tube expansion region starting from an expansion start portion of a molten resin tube extruded from a die and detects a diameter of the resin tube at the position, An inflation film forming apparatus having an air ring whose cooling air discharge amount is adjusted by a signal from a detector, wherein a support frame that can move up and down on the outside of the tube in parallel with a direction in which the tube is taken out holds the tube. The detector is provided on a machine frame of the molding apparatus in a surrounding state, and the detector is provided on a support bracket which is connected to a lower end of the support frame and is slidable in a horizontal direction along a horizontal rail positioned outside the tube. Each drive source of the support frame and the support bracket detects the position at the position corresponding to the blow-up ratio of the synthetic resin tube. An inflation film forming apparatus characterized in that it can be driven and controlled to adjust the position of the container. 2. A drive control device for the drive source, comprising: blow-up ratio setting means; calculating means for calculating the amount of movement of the support frame and the support bracket based on the selected blow-up ratio; 2. A blown film forming apparatus according to claim 1, further comprising means for driving each of said drive sources based on an amount. 3. An air ring cooling air discharge amount adjusting circuit is incorporated in the control device, and the cooling air discharge amount adjusting circuit receives an output signal of the detector and an output signal from the calculating means as input signals. 3. The blown film forming apparatus according to claim 2, wherein the discharge amount of the air ring is adjusted. 4. A pair of detectors are provided on the support bracket, one pair at the top and bottom, the amount of air blown by the air ring is increased when the upper and lower pairs are turned on, and the amount of air blown by the air ring is turned off when the two pairs are turned off. 4. The blown film forming apparatus according to claim 1, wherein the cooling air discharge adjusting circuit includes a drive control circuit for outputting a signal for reducing the pressure to the blower motor.