JPH05157522A - Measuring method of thickness of sheet and apparatus therefor - Google Patents

Abstract

PURPOSE:To improve the controlling efficiency of the thickness of a sheet without lowering the controlling accuracy when a bank is formed. CONSTITUTION:The thickness and temperature of a sheet 15 discharged out from a gap 13 of molding rolls 11, 12 are measured above a molding roll 11 immediately after the sheet 15 is carried out. The thickness of the sheet at a predetermined temperature is gained by correcting the thickness by the temperature. Accordingly, the thickness of the sheet can be detected positively without the detecting delay, and the correct control is realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet thickness measurement in forming a sheet of a plastic material, and more particularly to a sheet thickness measuring method in a bank forming and an apparatus therefor.

[0002]

2. Description of the Related Art As bank forming, as shown in FIG.
A flat die connected to an extruder (not shown) on the upstream side of the gap 13 between the pair of molding rollers 11 and 12 controlled in a desired temperature and rotating in pairs in the directions of arrows A and B. A plastic material 14 having a desired temperature is supplied from 10 in the form of a sheet, a pool of the plastic material 14, that is, a bank 14a is formed on the upstream side of the gap 13, and the plastic material 14 forming the bank 14a is formed into a forming roll 11 , The gap of the narrowest part by the rotation of 12 (hereinafter simply referred to as the gap)
There is a method in which the plastic material 14 is subjected to pressure molding by being drawn into the sheet 13 and is carried out as a sheet 15 to the downstream side of the gap 13.

In such bank forming, the thickness of the formed sheet 15 is measured, and the measurement result is used as a forming roll 11 which is a sheet thickness control unit in the bank forming.
The rotation speed control unit 12 and the gap 13 control unit, the lip adjusting unit 16 of the flat die 10, the choke bar 17, and an extruder (not shown) are fed back to form a sheet 15 having a desired thickness.

[0004]

By the way, heretofore, the sheet thickness meter is provided with the sheet 15 far ahead of the forming roll 18.
Since it is installed in a place where the sheet solidifies by cooling and becomes almost normal temperature, that is, a place where the sheet thickness is stable, there is a considerable distance between the bank forming part and the thickness measuring part, causing a relatively large detection delay. It was For this reason, the controllability is poor, and there is a drawback that it takes a relatively long time to rise from the start of molding to stable molding.

The present invention is to provide a sheet thickness measuring method and apparatus for improving controllability without deteriorating control accuracy.

[0006]

According to the present invention for achieving the above object, a plastic material is supplied to an upstream side of a gap between a pair of forming rolls which are arranged substantially parallel to each other and rotate. In the method of measuring the sheet thickness in sheet molding in which a roll is roll-formed into a bank while forming a bank on the upstream side of the gap, and is conveyed to the downstream side of the gap, the thickness of the conveyed sheet While measuring on the molding roll on the sheet winding side of the pair of molding rolls, the sheet temperature in the vicinity of the measurement point is measured, and the measured thickness information is corrected by the measured temperature information. To obtain the sheet thickness at a given temperature. The thickness information and the temperature information are preferably distributions at least at a plurality of positions in the width direction of the forming roll.

The present invention for achieving the above object
Is a pair of forming rolls that are arranged in parallel and rotate.
By supplying a plastic material to the upstream side of the gap,
By the forming roll, upstream of the gap of the forming roll
While forming a bank, press-mold it into a sheet to form the gap
Of the sheet thickness in the sheet forming that is carried out to the downstream side of the
In the constant device, the sheet of the pair of forming rolls
The winding side of the forming roll faces the sheet winding part, and
Sheet thickness arranged to measure the position near the sheet
Gauge and sheet temperature measuring device, and these sheet thickness gauges
And the output of the sheet temperature measuring device, and the sheet thickness meter
Output to the specified temperature by the output of the seat temperature measuring device.
Signal processing device to correct the sheet thickness in the
It is equipped with. In addition, the sheet thickness meter and sheet temperature
The degree measuring device is mounted so that it can scan in the width direction of the forming roll.
Preferably.

[0008]

The sheet carried out from the gap of the forming roll is conveyed while being wound around one forming roll, and the thickness and the temperature are measured on this forming roll, preferably at a position closer to the gap. Therefore, there is almost no delay in thickness measurement, and the controllability is greatly improved. This thickness gauge shows a value different from the thickness at a predetermined temperature such as room temperature because the sheet is at a high temperature. This difference is corrected by the output of the temperature measurement taken simultaneously with the thickness. Therefore, there is almost no decrease in control accuracy due to thickness measurement immediately after unloading or in the vicinity thereof, and more accurate control is possible.

[0009]

Embodiments of the present invention will be described below with reference to FIG. The flat die 10 is used in an extruder not shown,
Preferably, it is also connected via a gear pump (not shown), and is supplied with a plastic material 14 such as molten plastic or rubber. The plastic material 14 is controlled to a desired temperature by a heater (not shown), and the slit-shaped outflow portion 10a forms a sheet shape. Then, the forming rolls 11 and 12 (hereinafter referred to as the main roll 11 and the pressing roll 12 when individually referred to) are supplied to the upstream side of the gap 13. In addition,
Reference numeral 16 is a lip adjusting device, and 17 is a choke bar.

The forming rolls 11 and 12 allow a temperature-controlled fluid to flow therein and are controlled to a desired temperature.
It is rotated at a controllable predetermined speed in the direction indicated by. Gap 1
3 can be controlled to an appropriate value by moving the pressing roll 12 in the left-right direction in FIG. 1 by a gap adjusting device (not shown).

The plastic material 14 supplied in the form of a sheet on the upstream side of the gap 13 is so-called bank-formed by the forming rolls 11 and 12 to form a sheet 15. Since the bank-forming itself is the same as a known one. The detailed description is omitted.

A sheet thickness gauge 21 and a sheet temperature measuring device 22 are provided below the main roll 11 in FIG. The sheet thickness meter 21 uses an infrared transmission absorption type or a laser front and back reflection type sheet thickness gauge, and also an ultrasonic type, an optical type (scatter reflection type, specular reflection type), a capacitance type, etc. described later. Displacement gauge can be used. A radiation thermometer is preferably used as the seat temperature measuring device 22.

Sheet thickness gauge 21 and sheet temperature measuring device 2
The sheet 2 is wound around the main roll 11 and conveyed.
They are directed to positions close to each other with respect to the conveyance direction of No. 5, and are attached to the scanning head 23 to measure the sheet thickness and the sheet temperature at these positions. The scanning head 23 is attached to the apparatus frame 24 and is movable along a guide rail 25 extending substantially parallel to the main roll 11.

Sheet thickness gauge 21 and sheet temperature measuring device 2
The second output is taken into the signal processor 26 in association with the widthwise position on the main roll 11 given by the position of the scanning head 23. The signal processing device 26 corrects the output of the sheet thickness gauge 21 with the output of the sheet temperature measuring device 22 to obtain the sheet thickness at a predetermined temperature.

That is, the thickness of the sheet 15 is equal to that of the sheet 1.
The signal processing device 26 is previously provided with correction data according to the output from the sheet temperature measuring device 22 for each material of the sheet 15 and the like, because the signal processing device 26 changes in accordance with the sheet temperature due to contraction or the like due to the decrease in the temperature of the sheet 5. The output of the sheet thickness gauge 21 is corrected using this correction data, and the sheet 1
5 is configured to obtain the thickness when the temperature reaches a predetermined temperature such as room temperature.

Next, the operation of this device will be described. Plastic material 14 heated and melted by an extruder (not shown)
However, it is preferably supplied to the flat die 10 after being controlled to a desired flow rate by a gear pump, and is discharged at a predetermined temperature by a heater (not shown) provided in the flat die 10 to a predetermined temperature.

The plastic material 14 discharged from the flat die 10 forms a bank 14a on the upstream side of the gap 13 between the forming rolls 11 and 12, and the gap is generated by the pulling force of the forming rolls 11 and 12 generated according to the bank amount h. 13 is forcibly drawn in, is pressed by the forming rolls 11 and 12 while being cooled, and becomes a sheet 15, which is carried out to the downstream side of the gap 13 and is a main roll 11 and a subsequent forming roll of the pair of forming rolls. It is wound around 18 and is collected while being further cooled.

The sheet 15 leaving the gap 13 is the main roll 1
When the sheet is wound around the sheet 1 and conveyed, the sheet thickness gauge 21 and the sheet temperature measuring device 22 are scanned by the scanning head 23 to measure the thickness and the temperature, and the signal processing device 2
6 gives the thickness when the sheet 15 reaches a predetermined temperature such as room temperature.

The thickness of the sheet 15 at a predetermined temperature obtained by the signal processing device 26 is a portion for controlling the sheet thickness in bank forming, that is, the forming rolls 11 and 1.
It is fed back to the rotation speed control unit 2 and the control unit for the gap 13 and other publicly known control units to be used for sheet thickness control.

At this time, since the signal obtained from the signal processing device 26 is a sheet thickness signal relatively close to the gap 13, there is almost no detection delay and the signal is corrected to a sheet thickness of a predetermined temperature. Therefore, the sheet thickness can be accurately grasped, and more accurate control can be performed.

Needless to say, if the sheet thickness and the sheet temperature are measured at a position closer to the gap 13, the detection delay can be reduced. Also, the sheet thickness meter 2
In the case of using the above-mentioned ultrasonic type displacement meter in 1, the main roll 11 reaches a predetermined temperature and stabilizes in a state where there is no sheet 15, that is, before the start of sheet forming, and then the displacement meter measures the main roll 11 The surface displacement profile in the width direction is measured and stored in the signal processing device 26, and the surface profile of the sheet 15 is similarly detected during sheet forming,
The sheet thickness is calculated from both surface displacement profiles.

[0022]

As described above, according to the present invention, the sheet thickness immediately after being discharged from the gap between the bank-forming rolls is corrected to a predetermined temperature and measured. The controllability can be improved without deteriorating the control accuracy, and in particular, the effect of shortening the startup time at the start of molding can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

[Explanation of symbols]

 10 Flat Die 11 Forming Roll (Main Roll) 12 Forming Roll (Pressing Roll) 13 Gap 14 Plastic Material 15 Sheet 21 Sheet Thickness Meter 22 Sheet Temperature Measuring Device 23 Scanning Head 25 Guide Rail 26 Signal Processing Device

Claims (4)

[Claims] 1. A plastic material is supplied to an upstream side of a gap between a pair of forming rolls which are arranged substantially parallel to each other and rotated, and the plastic material is formed by the forming roll to form a bank upstream of the gap between the forming rolls. Meanwhile, in the sheet thickness measuring method in the sheet forming in which the sheet is pressure-formed into the sheet and conveyed to the downstream side of the gap, the thickness of the conveyed sheet is determined by forming the sheet winding side of the pair of forming rolls. Sheet thickness characterized by measuring on a roll, measuring the sheet temperature in the vicinity of the measurement location, and correcting the measured thickness information with the measured temperature information to obtain a sheet thickness at a predetermined temperature. Measuring method. 2. The sheet thickness measuring method according to claim 1, wherein the thickness information and the temperature information are distributions of at least a plurality of positions in the width direction of the forming roll. 3. A plastic material is supplied to an upstream side of a gap between a pair of forming rolls arranged substantially parallel to each other, and the plastic material is formed by the forming roll to form a bank upstream of the gap between the forming rolls. While measuring the sheet thickness in the sheet forming in which the sheet is pressure-formed and conveyed to the downstream side of the gap, the sheet winding portion of the pair of forming rolls facing the sheet winding portion of the sheet winding side. The sheet thickness meter and the sheet temperature measuring device arranged to measure the positions near the sheet and the output of the sheet thickness meter and the sheet temperature measuring device are taken in, and the output of the sheet thickness meter is measured. A sheet thickness measuring device, comprising: a signal processing device for correcting the sheet thickness at a predetermined temperature according to the output of the device. 4. The sheet thickness measuring device according to claim 3, wherein the sheet thickness meter and the sheet temperature measuring device are attached so as to be capable of scanning in the width direction of the forming roll.