JPS62246713A - Controlling film thickness in apparatus for manufacturing synthetic resin film - Google Patents

Abstract

PURPOSE:To prepare a film of a desired thickness, by measuring an extruded quantity per unit hour from an extruder, comparing this measured value with a preset value and adjusting thereby a rotating speed of a take-up roller of the film. CONSTITUTION:Width W and a thickness t of a required film and a density rhoof a material are input in a micro computer M is advance. On the other hand, photoelectric material detecting device 17, 18 are connected with the micro computer M and a consuming hour T for a specified vol. of a resin material is detected by a detecting means D from the acting interval of the photoelectric material detecting device 17. An extrusion output per unit hour in an extrusion cylinder 3 is calculated by means of a calculating device O from the consuming hour T and a vol. 12 of an apparatus 12 for supplying the material constantly. By comparing this calculated extrusion output with the product of the desired thickness t and width w having been input in advance and calculating a take-up quantity per unit hour corresponding to the calculated extruded quantity, a rotating speed of a take-up roller 4 is controlled.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is applicable to methods such as the inflatable method and the T-die method in which a synthetic resin film is formed by extruding a molten synthetic resin from an extruder. The present invention relates to a method for obtaining thick films.

(Prior Art) In general, when a synthetic resin is extruded from an extruder to form a film, the film thickness is adjusted by changing the rotational speed of the take-up reroller. The film thickness is measured using a dial dage, and the rotational speed of the take-up reroller is adjusted based on the measured value.

In addition, there is also a method in which the amount of extrusion from the extruder is calculated based on the screw speed of the extruder, and the rotational speed of the take-up reroller is adjusted from the calculated amount of extrusion.

(Problem to be solved) When the roller speed is adjusted by measuring the film thickness with a dial gauge, the measured values may vary depending on the skill level and physical condition of the worker, and the film thickness as a product may also vary. There is a problem with sticking.

In addition, in the case where the extrusion amount per hour is calculated from the screw speed and the roller rotation speed is set based on the calculated extrusion amount, there may be a difference between the calculated extrusion amount and the actual extrusion amount due to clogging in the extruder. This causes a problem in that the thickness of the film as a product fluctuates.

(Means for Solving the Problems) The present invention automatically supplies extruded resin material intermittently in constant weight increments in order to form a film with a desired thickness over the entire length. The amount of extrusion per unit time from the extruder is actually measured by measuring the consumption time of the resin material supplied to the extrusion tube or the number of times it is supplied within a certain period of time, and this actual value is compared with the preset value. This feature is characterized in that the rotational speed of the take-up reroller is adjusted and controlled by comparing it with the set value that has been set.

(Function) In the present invention, it is possible to detect the time taken to consume a certain weight of resin material that is intermittently supplied, or to detect how many times a certain weight of resin material is fed to the extrusion tube within a certain period of time. By this, the amount of resin actually extruded from the extruder per hour is calculated, and from this calculated extrusion amount and the preset film width and film thickness, the take-off length per hour is calculated. The rotational speed of the take-off roller is adjusted and controlled so that the take-off length is achieved. In this case, since the extrusion amount is the actually measured value, the film thickness of the product is stabilized at the desired value.

(Example) FIG. 1 is a flowchart of the method of the present invention, and FIG. 3 is a schematic diagram showing a synthetic resin sheet manufacturing apparatus using an inflation method.

This resin sheet manufacturing device (1) has a spiral conveyance shaft (
2) arranged in the axial direction; a take-up reroller (4) that takes over the molten synthetic resin extruded from the extruder reroller (3); A winding section (5) that winds up a resin sheet and an extrusion tube (3)
It consists of a raw material supply tool (6) that supplies granular synthetic resin material, and a heater (not shown) is arranged in a part of the cylinder of the extrusion tube (3), and a heater (not shown) is arranged in a part of the cylinder of the extrusion tube (3). The synthetic resin material supplied to the tube melts while being transferred inside the extrusion tube (3), passes through the screen (7) placed at the tip of the extrusion tube (3), and is then transferred from the guide (8) to the tube. It is extruded in a shape.

The raw material supply tool (6) is connected to the lower end of the hopper (9) and the extrusion tube (
A material quantitative supply device (
12). This material quantitative supply device (
12) has an upper lid (15) and a lower lid (16) driven by air cylinders (13) and (14), respectively,
By selectively and alternately opening and closing the upper lid (15) and the lower lid (16), the volume of the space formed by the upper lid (15), the lower lid (16), and the inner circumferential wall of the material supply pipe (11) can be increased. A certain volume of synthetic resin material is dropped into the material input port (10) using a volume of . An internal volume adjusting device (21) is installed in this square section, and this internal volume adjusting device (21) adjusts the internal volume when using materials with different specific gravity or shape. This allows the material to be supplied to the material supply port (10) by quantifying its weight.

A pair of upper and lower photoelectric material detectors (17) are installed in the open material supply path between the material quantitative supply device (12) and the material input port (10).
(18) are arranged vertically at appropriate intervals, and as the molten synthetic resin is extruded from the extrusion cylinder (3), the material accumulated in the material supply path descends, and the material When the lower material detector (17) detects that the amount of material accumulated in the supply path has become less than a certain amount, the air for driving the lower lid of the light material quantitative supply device (12) is activated based on the detection signal. When the cylinder (13) is advanced and the lower cover (16) is opened, the upper material detector (18) detects that the fallen material has accumulated at a certain height in the material supply path. Based on the signal, the outer lower M (16) is operated to close. A proximity switch (19) is provided near the base end of the lower lid driving air cylinder (13), and when the air cylinder (13) moves in and out to close the lower lid (16), the proximity switch (19) is activated, the upper lid driving air cylinder (14) is advanced and the upper II (15) is opened, and the hopper (
9) Drop the material in the container into the material quantitative supply device (12). This upper lid (15) is closed by a timer (20).

Next, a method for controlling film thickness using the above-mentioned apparatus will be described.

First, as a preliminary operation, the width (w) and thickness (1) of the desired film and the density (ρ) of the material are input into the microcomputer (M). On the other hand, rechargeable material detection (17) (
1B) is connected to the microcomputer (M), the consumption time (T) of a certain amount of resin material is detected by the detection means (D) from the operation interval of the photoelectric material detection (17), and the consumption time (T ) and the volume (V) of the material quantitative supply device (12), the amount of extrusion per unit time in the extrusion tube (3) is calculated by the calculation means (O). Then, by comparing and calculating this calculated extrusion amount with the product of the desired film thickness (1) and membrane width (111), which are input in advance, by the comparison means (C), the unit time corresponding to the calculated extrusion amount is calculated. A hit take-off amount is calculated, and the rotational speed of the take-off roller (4) is controlled so as to achieve this take-up amount.

In this case, the consumed time may be detected based on the time difference between when the upper rechargeable detector (18) is activated and when the upper rechargeable detector (17) is activated.

Alternatively, it may be possible to detect how many times the material quantitative supply device (12) is operated within a certain period of time, and calculate the material consumption amount per unit time based on the detection result.

In summary, the method of the present invention is based on the inflation method and T
The resin material taken into the extrusion tube (3) in accordance with the amount of extrusion from the extrusion tube (3) by the die method is transferred to the material input port (10).
) is intermittently supplied at a constant volume to The take-off speed corresponding to the desired film thickness and film width is calculated from the extrusion amount, and the rotation speed of the take-off reroller is controlled to achieve the take-off speed.

(Effects) In the present invention, the actual extrusion amount is calculated from the consumption time of the material that is intermittently supplied at a constant rate. Even if the goo is clogged, the amount being extruded from the goo can be accurately measured. Furthermore, since the take-up speed at which the desired film thickness is achieved is calculated from the actual extrusion amount and the rotation speed of the take-up roller is controlled,
Even if the extrusion speed within the extrusion cylinder fluctuates, the thickness of the product film can be maintained constant.

Furthermore, since the roller rotation speed is controlled by calculating the take-up speed from the extrusion amount, the take-up speed can be set to maintain a constant film thickness without being affected by the operator's skill level or physical condition. be able to.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing a control procedure, and FIG. 2 is a schematic diagram of a film manufacturing apparatus using an inflation method. 3... Extrusion tube, 4... Take-up roller, D... Consumption time detection means, 0... Extrusion amount calculation means, C... Comparison means.

Claims (1)

[Claims] 1. When extruding synthetic resin from the extrusion tube (3) to form a synthetic resin film, a constant weight of resin material is automatically and intermittently supplied to the extrusion tube (3), and the resin material is intermittently supplied to the extrusion tube (3). The detection means (D) detects either the time for consuming a certain weight of the resin material or the number of times the resin material is supplied to the extrusion cylinder (3) per unit time, and the detection means (D)
The calculation means (O) calculates the amount of extrusion per unit time from the extrusion tube (3) using the output signal from the extrusion tube (3), and compares the output from the calculation means (O) with a preset value. ), and the thickness of the film sheet is formed to a constant thickness by controlling the rotational speed of the take-up roller (4) based on the output from the comparison means (C). Film thickness control method in synthetic resin film manufacturing equipment