JPH0825463A - Extrusion molding method and apparatus - Google Patents

Abstract

PURPOSE:To inexpensively perform extrusion molding capable of continuously producing a film or sheet free from irregularity as a product and enhancing the capacity of adjustment and control operation while dispensing with a raw material shutter and a raw material opening and closing cylinder used heretofore to simplify constitution. CONSTITUTION:In an extrusion molding method wherein the raw material 2 in a raw material hopper 1 is supplied to an extruder 7 and melted in the extruder 7 to be extruded from a die 10 and the extrudate is formed into a film or sheet to be taken up, the raw material consumption wt. per a unit time of the raw material 2 supplied to the extruder 7 from the raw material hopper 1 is continuously measured and a taking-up speed is adjusted corresponding to the measured raw material consumption wt. to control the taking-up speed so as to hold the width and thickness of the film or sheet to set values.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention produces a film or sheet by discharging a molten resin material such as a thermoplastic resin with a die having an annular discharge port or a die having a linear discharge port such as a T-die. Extrusion molding method and apparatus.

[0002]

2. Description of the Related Art Generally, in an extrusion molding method such as an inflation molding method, adjustment is performed so as to always maintain the width and thickness of a film or sheet to be produced at set values.

In order to perform this adjustment manually, a long period of skill and experience was required.

Therefore, in order to rationalize this problem in recent years,
An automatic adjustment control method for automatically performing the adjustment has been proposed (Japanese Patent Laid-Open Nos. 1-24711, 1-26).
424, etc.).

This automatic adjustment control system will be further described with reference to FIG. 3, in which the raw material 2 charged into the raw material hopper 1 goes through a raw material shutter 3 opened / closed by a raw material opening / closing cylinder 4, a weight measuring machine 5, and a weighing pot 6 in order. It is supplied to the inside of the heating cylinder 8 of the extruder 7. Thereafter, the raw material 2 is melted while being transferred in the heating cylinder 8 by the rotation of the screw 9, is discharged from the annular discharge port of the die 10, and is blown by the air supplied into the bubble 11 to be thin film. And is taken by the pinch roller 12.

Actually, the raw material 2 in the measuring kettle 6 is consumed by feeding the raw material 2 by the screw 9,
When the lower limit set value sensor 14 measures the lower limit set value, the raw material open / close cylinder 4 and the raw material shutter 3 are turned on to drop the raw material 2 from the raw material hopper 1 to the weighing vessel 6, and the upper limit set value sensor. It is turned off when the upper limit set value is measured at 13 to stop the fall of the raw material from the raw material hopper 1.

At this time, the extrusion amount is calculated by measuring the unit raw material consumption time from the moment the upper limit set value is turned on to the moment it is turned off until the lower limit set value is turned on. Furthermore, the take-up speed is calculated from the value of the cross-sectional area and the specific gravity of the product obtained by the calculated extrusion amount and the preset width and thickness of the film or sheet, and the signal from the automatic take-up speed control board 15 is used. Pinch roller 1
The rotation speed of 2 is controlled.

[0008]

However, in the conventional examples described in the above-mentioned respective publications, the time measurement of a small lot capacity unit for measuring the time to consume the unit material or the time to turn on / off the material opening / closing cylinder 4 Is the way
Therefore, the raw material shutter 3 and the raw material opening / closing cylinder 4 are necessary, and further, the following drawbacks are present.

Disadvantage 1 Due to the structure in which the capacity of the raw material between the upper limit setting value and the lower limit setting value of the raw material kettle 6 is measured as one unit, it takes too much time to reach the lower limit from the upper limit when the extrusion amount is extremely small. And the control becomes defective, and the pinch roller 12 as a take-up device
It may not be possible to link with.

Disadvantage 2 Since the raw material shutter 3 is opened and closed by the raw material opening / closing cylinder 4, the raw material shutter 3 is clogged with the raw material 2 and cannot be operated, or when the raw material shutter 3 is changed to a different type of raw material, the raw material clogged the day before is removed. They had problems such as getting in and changing colors.

Disadvantage 3 Since the upper limit setting value and the lower limit setting value of the raw material kettle 6 are provided and the measurement is carried out in units of small lots, the drop of the raw material 2 (the time from the setting of the upper limit value to the closing of the raw material opening / closing cylinder 4) In the meantime, the amount of raw material that enters the raw material pot 6 is delayed.

Disadvantage 4 The time from the upper limit set value to the lower limit set value is measured, but conversely, the time from the lower limit set value to the upper limit set value is not measured. Therefore, the measurable region and the non-measurable region are repeated over time, which causes a time delay and deteriorates the resolution.

Disadvantage 5 Since the material shutter 3 and the material opening / closing cylinder 4 need to be installed, the machine cost becomes high.

Disadvantage 6 Since the raw material shutter 3 and the raw material opening / closing cylinder 4 are generally near the working environment, there is a risk of injury.

Disadvantage 7 Generally, since the measuring kettle 6 is small, the amount of the raw material 4 biting into the extruder 7 is different near the upper limit setting value and the lower limit setting value, so that the extrusion amount varies. .

Disadvantage 8 Since the capacity of a small lot measured between the upper limit set value and the lower limit set value is the unit of measurement, it is impossible to measure in a cycle shorter than the time measured during this period. As a result, the control performance deteriorates.

The present invention has been made in view of these points. The raw material consumption weight per unit time is continuously measured for a certain period of time, and the take-up speed of the film or sheet is adjusted based on the measurement result. Then, the operation control of the take-up speed for maintaining the width and thickness of the film or sheet at the set values can be continuously performed for at least the time, and continuous production of the film or sheet without variation as a product can be performed. It is an object of the present invention to provide an extrusion molding method and apparatus that can improve the performance of these adjustment control operations, eliminate the need for a conventional material shutter, a material opening / closing cylinder, and the like, simplify the configuration, and reduce the cost. .

[0018]

In order to achieve the above-mentioned object, the extrusion molding method of the present invention comprises supplying a raw material in a raw material hopper to an extruder, melting the raw material by the extruder, and extruding from a die, Then, in the extrusion molding method in which the raw material is taken out in the form of a film or a sheet, the raw material consumption weight per unit time of the raw material supplied to the extruder from the raw material hopper is continuously measured, and the measured It is characterized in that the take-up speed is adjusted according to the consumed weight of the raw material, and the take-up speed is operationally controlled so as to maintain the width and thickness of the film or sheet at set values.

The extrusion molding apparatus of the present invention comprises a raw material hopper, an extruder for melting the raw material supplied from the raw material hopper and extruding it from a die, and an extruded raw material in the form of a film or a sheet. In an extrusion molding apparatus having a take-up means for taking a variable take-up speed, a raw material weight measuring device for measuring a total weight of the raw material hopper and an internal raw material, and a raw material based on a change in the measured raw material weight. The raw material consumption weight per unit time is calculated, and according to the obtained raw material consumption weight, the width and thickness of the film or sheet are maintained at set values. And a take-up speed controller.

[0020]

By operating the apparatus of the present invention according to the method of the present invention, the raw material consumption weight per unit time is continuously measured for a certain period of time, and the take-up speed of the film or sheet is adjusted based on the measurement result. The operation control of the take-up speed for maintaining the width and thickness of the film or sheet at the set values can be continuously performed at least during the time, and continuous production of the film or sheet without variation as a product can be performed.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows an embodiment of the extrusion molding apparatus of the present invention, in which the same parts as those in the prior art are designated by the same reference numerals.

In this embodiment, the raw material shutter 3, the raw material opening / closing cylinder 4, and the weighing machine 5 in the conventional example of FIG. 3 are used.
And the weighing vessel 6 is omitted, a raw material hopper support stand 16 is provided around the raw material input port 7a of the extruder 7, and at least the total weight of the raw material hopper 1, the raw material 2, and the raw material supply loader 18 can be measured. The measuring device 17 is installed, and the raw material hopper 1 is installed thereon. The raw material 2 is automatically supplied from the raw material supply loader 18 to the raw material hopper 1. In order to increase the measurement sensitivity of the raw material weight measuring device 17, the raw material supply loader 18 may not be placed directly on the raw material hopper 1. The weight measured by the raw material weight measuring device 17 is input to the take-up speed controller 19. The take-up speed controller 19 includes a raw material consumption weight calculation unit 20 for calculating the raw material consumption weight per unit time of the raw material from the change in the measured weight input from the raw material weight measuring device 17, and the obtained raw material consumption weight. Accordingly, a take-up speed calculation unit 21 that issues a command to the drive source to rotationally drive the pinch roller 12 that is the take-up means at a take-up speed that maintains the width and thickness of the film or sheet at set values. Have The calculation of the take-up speed is performed by calculating the raw material consumption weight calculated by the raw material consumption weight calculation unit 20, that is, the extrusion amount of the extruder, and the cross-sectional area and specific gravity of the product obtained by the preset width and thickness of the film or sheet. It is calculated by dividing by the product value of. The take-up speed calculator 21 may be formed by a computer or the like. The other structure is formed in the same manner as the conventional example.

Next, the operation of this embodiment will be described with reference to FIG.

At time t0, the extrusion molding apparatus is continuously molding the film in a steady state, and the raw material hopper 1 is filled with the raw material 2 in the maximum amount.

From this time, as the screw 9 rotates,
The raw material 2 in the raw material hopper 1 is consumed by the raw material 2 in the raw material hopper 1 being supplied into the heating cylinder 8 through the raw material charging port 7a. As a result, the amount of the raw material 2 in the raw material hopper 1 decreases with time from t0 to t1 as shown by the line a in FIG. During this time t0 to t1, the raw material weight measuring device 17 measures the total weight of the raw material hopper 1, the raw material 2 and the raw material supply loader 18, and the measured weight is continuously calculated by the raw material consumption weight of the take-up speed controller 19. It is output to the unit 20. The raw material consumption weight calculation unit 20 calculates the raw material consumption weight per unit time of the raw material 2 from the change in the measured weight input from the raw material weight measuring device 17, and outputs it to the take-up speed calculation unit 21. This take-up speed calculator 21
Is the raw material consumption weight calculated by the raw material consumption weight calculation unit 20, that is, the extrusion amount of the extruder, is divided by the product value of the cross-sectional area and the specific gravity of the product obtained by the preset width and thickness of the film, A take-up speed that maintains the width and thickness of the film at set values is calculated, and the take-up speed is emitted toward a drive source that rotationally drives the pinch roller 12, and the pinch roller 12 is rotationally driven at the take-up speed. . As a result, continuous operation is carried out at a take-up speed that maintains the width and thickness of the film at set values, so that a film with uniform quality is produced.

In the next t1 to t2 hours, the raw material 2 is supplied from the raw material supply loader 18 into the raw material hopper 1 in order to continue the subsequent extrusion molding operation. At this time, the measurement of the total weight of the raw material hopper 1 and the raw material 2 by the raw material weight measuring device 17 is interrupted.

After the time t2, the same operation as the time t0 to t2 is repeated.

When the extrusion molding method according to the present embodiment is compared with the conventional example, the conventional method is a discontinuous time measuring method in units of small lots, whereas the method of the present invention is almost continuous during measurement. Since it is a continuous operation and the amount of material consumed per unit time is directly measured to calculate the extrusion amount, there is no error in measurement or calculation, and the material opening / closing shutter etc. that was conventionally required can be used. Since it is unnecessary and continuous measurement is performed, there is an advantage that the control performance is greatly improved.

The present invention further has the following advantages.

Advantage 1 Since the raw material consumption amount per unit time is continuously measured for a certain period of time, the response of control and the decomposition performance can be improved by narrowing this unit time, and the extrusion amount is extremely high. Stable control is possible even when the number is very small.

Advantage 2 There is no problem such as a problem that the conventional material shutter is clogged with the material, or a problem that the material clogged on the previous day is taken in when the material of a different type is replaced.

Advantage 3 Since there is no need for a raw material open / close cylinder and the like, there is no need to process the head of raw material, so there is no time delay.

Advantage 4 Machine cost is low because there is no material opening / closing cylinder.

Advantage 5 Since there is no material opening / closing cylinder, there is no risk of injury due to it.

Advantage 6 Since the weight of the raw material hopper itself is measured, the raw material hopper can have a sufficient size and structure,
It is possible to supply the raw materials in a fixed amount, and there is no fluctuation in extrusion. In the conventional small measuring kettle, the amount of the bite of the raw material is hard to be constant, and therefore, the extrusion fluctuation is likely to occur.

Advantage 7 Since the operation is continuous during the measurement and the extrusion weight is calculated by directly measuring the weight consumption of the raw material per unit time, there is no measurement error.

It should be noted that the present invention is not limited to the above embodiment, but can be modified as necessary.

[0039]

As described above, since the extrusion molding method and apparatus of the present invention are constructed and operate, the weight consumption of the raw material per unit time is continuously measured for a certain period of time, and the film is measured based on the measurement result. By adjusting the take-up speed of the film or sheet and maintaining the width and thickness of the film or sheet at the set values, operation control of the take-up speed is continuously performed for at least the time, and the film or sheet does not vary as a product. It is possible to carry out continuous production, improve the performance of these adjustment control operations, eliminate the need for conventional material shutters and material opening / closing cylinders, simplify the configuration, and reduce the cost. Play.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of an extrusion molding apparatus of the present invention.

FIG. 2 is a time chart showing the implementation of the extrusion molding method of the present invention.

FIG. 3 is a schematic view showing an example of a conventional extrusion molding apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Raw material hopper 2 Raw material 7 Extrusion device 10 Die 12 Pinch roller 17 Raw material weight measuring device 19 Taking-up speed controller 20 Raw material consumption weight calculating unit 21 Taking-up speed calculating unit

Claims (2)

[Claims] 1. A raw material in a raw material hopper is supplied to an extruder,
In the extrusion molding method in which the raw material is melted by this extruder and extruded from the die, and then the raw material is taken in a film or sheet shape, the raw material is supplied to the extruder from the raw material hopper per unit time. The consumption weight is continuously measured, and the take-up speed is adjusted according to the measured raw material consumption weight, and the take-up speed is controlled so as to maintain the width and thickness of the film or sheet at the set values. An extrusion molding method comprising: 2. A raw material hopper, and an extruder for melting the raw material supplied from the raw material hopper and extruding it from a die,
In an extrusion molding apparatus having a take-up means for taking a film or sheet-like extruded raw material with a variable take-up speed, a raw material weight measuring device for measuring the total weight of the raw material hopper and the internal raw materials. And the raw material consumption weight of the raw material per unit time from the change of the measured raw material weight, and the take-off speed for maintaining the width and thickness of the film or sheet at the set values according to the obtained raw material consumption weight. And a take-up speed controller for issuing a command to drive the take-up means.