JPH01291107A - Method and device for measuring profile of plastic sheet - Google Patents

Abstract

PURPOSE:To measure a profile of a sheet with high accuracy by bringing a relation of a light emitting part and a light receiving part of a sensor head to position setting in the transfer direction of a plastic sheet or in its opposite direction. CONSTITUTION:A sensor head 26 consists of a light emitting part for irradiating the surface of a plastic sheet S by a laser beam, and a light receiving part for receiving a reflected light from the surface and the reverse side of the sheet S and detecting their interval. At the time of attaching the head 26, the light emitting part and the light receiving part are positioned so that an irradiation and a reflection of the light beam are executed in parallel to the transfer direction of the sheet S or its opposite direction. A sheet thickness output signal which is detected by the head 26 and outputted is inputted to a CPU 40 together with a scan position signal from a driving motor 36, the sheet thickness is calculated by a prescribed expression, stored and brought to statistical operation processing for a graphic display. In such a way, said head takes a state that measuring points of the reflected light on the surface and the reverse side of the sheet are erased mutually, and the generation of an error is prevented effectively.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention irradiates the surface of a continuously extruded plastic sheet with a beam of light such as a laser, and generates a difference between the reflected light on the front and back surfaces. The present invention relates to a method and apparatus for measuring sheet thickness from spatial spacing.

[Conventional technology]

Generally, it is required for product quality control to measure the widthwise thickness distribution (usually referred to as profile) of plastic sheets that are continuously manufactured using an extrusion molding machine. Conventionally, for such profile measurements, an optical scanning thickness needle or the like has been used, which is equipped with a measurement head that moves back and forth in the width direction of a part of the product conveyance path.

However, conventionally, as this type of thickness gauge, the transmission absorption type β
Line thickness needles and infrared thickness needles and contact thickness gauges are used. The β-ray thickness needle uses srqO as the β-ray and measures relatively thick sheets, but the upper limit of the measurable thickness is about 5n. In addition, the infrared thickness gauge is P
By using a wavelength in the near-infrared region with a bS sensor, it is possible to measure thicknesses up to about Ions, but there is a drawback that the measurement accuracy is reduced due to the low sensitivity coefficient. Furthermore, contact type thickness gauges are affected by sheet warpage and bending of the reference roll, and therefore have the disadvantage that the thicker the sheet, the larger the measurement error.

Today, plastic sheets are made of methacrylic resin (PMMA), polycarbonate (PC), vinyl chloride (PVC), polystyrene (PS), etc.
There is an increasing demand for transparent products such as polyethylene terephthalate (PET) plates, and when forming such transparent sheets, it is necessary to measure the profile and manufacture sheets with uniform thickness. In this case, conventional thickness gauges cannot be used with high accuracy over a wide range of sheet thicknesses, and contact type thickness gauges in particular cannot be used because they damage the product.

From this point of view, as a means of measuring the thickness of a transparent or translucent sheet, a light beam such as a laser is used to irradiate the sheet surface at a predetermined angle of incidence. A thickness needle is known that can measure the sheet thickness by using the reflected light, which causes significant reflection on the back surface. In other words, the principle of this thickness needle is as shown in Fig. 10, where the incident angle of the light beam on the sheet surface is i, the interval between the reflected light beams reflected on the sheet surface and the back surface is D, and the thickness of the sheet is If the refractive index of the light beam is n, then the sheet thickness y can be determined by the following equation.

y=D,, (1)s
in 2 i In this case, the refractive index n and the incident angle i are known numbers, so it is easy to measure the distance by detecting the reflected light using a linear image sensor or a special optical-to-electrical conversion system. The sheet thickness y can be measured.

However, the plastic sheet molding process is generally configured as shown in FIG.

That is, in FIG. 11, reference numeral 10 indicates an extruder;
12 is a lower die for sheet forming, 14 is a forming roll unit, 6 is a scanning thickness gauge, 18 is a protective paper supply unit, 2
0 is a take-up roll unit, 22 is a sheet cutting machine, 24
indicate sheet loading machines. Here, as shown in FIG. 12, the scanning thickness gage 16 is provided with a gate-shaped frame 2 for supporting the sensor head 26, and the center portion of this frame 28 is attached to the sensor head 26. It is configured so that the plastic sheets S that are continuously molded facing each other pass through. Therefore, a rail 30 is provided on the top of the frame 28 along the longitudinal direction of the frame 28, and the sensor head 2G is suspended on the rail 30 so as to be freely movable.
This sensor head 26 is engaged with an endless belt 34 that is wound around boots J32, 32 provided at both ends of the top of the frame 28, and one pulley 32 is configured to be reversibly rotated by a drive motor 36. In this way, the sensor head 26 can easily measure the profile of the plastic sheet by appropriately scanning the continuously transported plastic sheet S.

In this case, the sensor head 26 is configured to include a laser light source, a reflected light sensor, etc., and is configured and arranged so that, for example, the incident direction and the reflected direction of the light beam coincide with the reciprocating direction of the sensor head 26. As a result, it was confirmed that profile measurement of transparent or translucent plastic sheets can be achieved with high accuracy over a wide range of sheet thickness.

[Problem to be solved by the invention]

However, according to the thickness measurement method that uses the reflected light of the plastic sheet S as described above, as is clear from FIG. 10, the measurement points (
Since there is a deviation (ΔX) at the reflection point, the influence of this deviation on the gap in the re-reflected light cannot be ignored, especially when the sheet becomes thick. In this case, the deviation amount X can be expressed by the following equation.

sin i For example, based on equation (2) above, the incident angle of the light ray is 1x49.
2°, refractive index n-=1.49 (PMMA), the amount of deviation ΔX is 0.59y, and if the thickness y=10mm, the measurement point will be deflected by about 5 I1m, It is expected that measurement errors will also increase.

In addition, in the plastic sheet molding process, T
The molten resin extruded from the die is cooled by heat radiation to the rolls and the atmosphere during the process of being formed into a sheet. However, since plastic materials generally have low thermal conductivity, they are slowly cooled to prevent distortion in the sheet, so the average temperature of the sheet at the measurement position of the profile is △ below room temperature.
θ is in a high state. When the profile of a sheet in such a high temperature state is measured with a thickness needle based on the above-mentioned FIG. 10 and the above-mentioned formula (11), measurement errors occur due to the following two factors.

■ Error due to thermal expansion of the sheet (△yt) ■ Error due to change in refractive index of the sheet (△y2) Calculate the magnitude of the measurement error due to these factors by assuming △θ = 30°C for a PMMA sheet with a thickness of 10 mm. It becomes as follows. First, the error Δy is immediately calculated as Δy, since the standard linear expansion coefficient α below the glass transition point is approximately 6×10−′.
x average is 18 μm. Furthermore, the error △y2 is PMM
The refractive index n of the A sheet is 1.49 at room temperature, and its value decreases as the temperature rises higher than this, and its temperature coefficient μ is approximately 1.1 x 10-4, so these can be expressed using the above formula (1 ), it becomes Δy2#30 μm. Therefore, when these errors are combined, it is approximately 0.48% at approximately 48 μm.
This is an error that cannot be ignored in terms of precise profile measurement.

Furthermore, in the plastic sheet molding process, as shown in FIG. 13, a neck-in phenomenon occurs during the process in which the molten resin extruded from the T-die 12 is molded into a sheet via the molding rolls 14, so The sheet is designed to be formed with enough width, and then both ends of the sheet are trimmed to make it to the standard width. That is, the sheet width X1 before trimming is expressed as X1=W-B (B is the reduced width caused by the neck-in phenomenon, etc.), where W is the width of the molding opening of the T-die 12. Then, the sheet is finally trimmed at both ends and finished to a standard width of X2, but in this case, the yield of the product is X2/Xi, so
The sheet width X is required to be as small as possible. The reduction@B changes depending on the amount of neck-in occurring in the forming roll portion, the size of the melt bank, etc., so the sheet width X before trimming.

is not necessarily stable. For this reason, the width of the molded sheet must be set wide to avoid producing defective products.
This increases the amount of trimming, lowers the yield, and is disadvantageous in terms of manufacturing costs. Therefore, due to these circumstances,
In addition to measuring the profile of plastic sheets, it is also extremely important to measure the sheet width with high accuracy.

Therefore, an object of the present invention is to irradiate the surface of a plastic sheet that is continuously molded by an extruder using a laser beam or the like with a small beam diameter and good directionality and response. To provide a method and apparatus for measuring the profile of a plastic sheet, which can measure the profile of the sheet with high precision by detecting the sheet thickness from the spatial gap generated between the light reflected from the front and back surfaces of the sheet. .

Another object of the present invention is to perform highly accurate measurement of a continuously molded plastic sheet by the above measuring method and apparatus, so that the sheet expands and the refractive index changes based on the sheet temperature during molding. An object of the present invention is to provide a plastic sheet profile measuring method and apparatus for correcting errors by using measured values measured in a cooled state as appropriate measured values after cooling.

Furthermore, it is an object of the present invention to obtain plastic products with more stable quality by using the above-mentioned measuring method and apparatus, and to improve the yield by trimming to obtain products with a fixed width. An object of the present invention is to provide a method and apparatus for measuring the profile of a plastic sheet that accurately measures the width of the sheet at the same time as measuring the profile of the plastic sheet.

[Means for Solving the Three Problems] The plastic sheet profile measuring method according to the present invention uses a light source such as a laser that irradiates the surface of a plastic sheet at a required angle of incidence, and a light source that irradiates the surface of the plastic sheet at a required angle of incidence, and the reflection reflected from the front and back surfaces of the sheet. A sensor head is provided with a sensor for detecting the respective intervals of light, and the sensor head is set so that the direction of the incident light and the reflected light with respect to the continuously molded plastic sheet is parallel to the transport direction of the sheet or the opposite direction thereof. At the same time, the sheet thickness is measured by moving the sheet back and forth in the width direction of the sheet.

In this case, the sensor head is equipped with a temperature sensor that measures the surface temperature of the plastic sheet, and this temperature measurement value is used to correct the sheet thickness error due to the thermal expansion of the sheet and the change in the refractive index of light. More accurate measurements can be achieved.

Furthermore, with the seat edge detected by the profile measurement data as a reference, the shift position and its speed below the standard speed are set inside the seat edge, and the turning point position is set on the outside of the seat edge. It is possible to control the reciprocating movement of the sensor head based on the set value of and measure the sheet width of a continuously molded plastic sheet.

The apparatus for implementing the profile measurement method includes a light source such as a laser that irradiates the surface of the plastic sheet at a required angle of incidence, and a sensor that detects the intervals between the reflected lights reflected from the front and back surfaces of the sheet. A sensor head is provided, and the sensor head is set so that the direction of incident light and reflected light on a continuously molded plastic sheet is parallel to the transport direction of the sheet or the opposite direction, and the sensor head is reciprocated in the width direction of the sheet. A drive motor is movably suspended on a frame and controls the reciprocating movement of the sensor head, and a sheet thickness output signal detected by the sensor head and a scan position signal detected from a control system of the drive motor are respectively input. It can be constructed by providing a computing unit that performs profile measurement.

Furthermore, in the profile measuring device described above, a radiation thermometer for measuring the surface temperature of the plastic sheet is provided in the sensor head, and the temperature signal measured by the radiation thermometer is inputted together with the sheet thickness output signal and the scan position signal. It is preferable to provide an arithmetic unit that performs corrective calculations for sheet thickness errors due to thermal expansion and changes in the refractive index of light, and performs proper profile measurements.

Furthermore, a motor controller is provided for the drive motor that controls the reciprocating movement of the sensor head, and a setting device that sets the sensor head speed, shift position, and turning point position for the motor controller, and a setting device that detects the scan position of the sensor head. and a converter that outputs the position signal, and calculates the set value to the setting device based on the sheet edge detected by the profile measurement data measured by the sensor head, and continuously molds the plastic sheet. It is preferable to provide an arithmetic unit that measures the sheet width.

[Effect]

According to the method for measuring the profile of a plastic sheet according to the present invention, the profile of a transparent or translucent plastic sheet, which has conventionally been determined, is determined by using a light beam such as a laser and determining the distance between the reflected light from the front and back surfaces of the sheet. Measurements can be easily accomplished. In this case, the sensor for emitting the light beam and sensing the reflected light to obtain the desired output signal measures the front and back surfaces of the sheet by setting the direction of the light beam parallel to the transport direction of the plastic sheet. Errors due to point deviation can be minimized.

In addition, since the plastic sheet is still in a high temperature state at the time of profile measurement, errors in sheet thickness occur due to thermal expansion of the sheet and changes in the refractive index of light. Therefore, the surface temperature of the sheet is measured at the same time as the profile measurement. It becomes possible to correct the thickness error caused by the thermal expansion and the change in the refractive index of light, thereby further increasing the accuracy of profile measurement.

Further, according to the present invention, by using a sensor head that can perform highly accurate profile measurement, the shift position and the turning point position of the sensor head are determined based on the sheet edge detected by profile measurement data. With proper settings, it is possible to efficiently control the reciprocating movement of the sensor head, and as a result, it is possible to measure sheet width and quickly and accurately detect abnormal changes in sheet width and sheet thickness. However, it is possible to easily improve the productivity of plastic sheets and reduce manufacturing costs.

〔Example〕

Next, an embodiment of the method for measuring the profile of a plastic sheet according to the present invention will be described in detail in relation to an apparatus for carrying out the method, with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing the configuration and arrangement of a thickness gauge for carrying out the method for measuring the profile of a plastic sheet according to the present invention. The basic configuration of the thickness gauge shown in Figure 1 is the same as the configuration shown in Figure 12 described above, so for convenience of explanation, the same reference numerals will be given to the same components and the detailed description will be omitted. Explanation will be omitted. Although not shown, the sensor head 26 used in this embodiment includes a light emitting section that irradiates a laser beam at a required angle of incidence onto the surface of the plastic sheet S facing the opposite surface, and a light emitting section that irradiates the surface of the plastic sheet S from the front and back surfaces of the plastic sheet S. The sheet thickness sensor includes a light receiving section that detects the reflected light and the interval therebetween, and is configured to output a required sheet thickness signal from the output terminal.

However, in the present invention, the reflected light detected by the sensor head 26 has a deviation (△X) between the measurement points on the front surface of the sheet and the back surface of the sheet, which causes an error in the measured value of the sheet thickness. As shown in FIG. 2, the light emitting part and the light receiving part are positioned so that the light rays are irradiated and reflected in parallel to the transport direction of the continuously molded plastic sheet S or the opposite direction, and the sensor head 26 The feature is that the installation is carried out. In this way, the sensor head 26
By setting the relationship between the light-emitting part and the light-receiving part not in the scanning direction of the plastic sheet S, but in the transport direction of the plastic sheet S or in the opposite direction, the measurement points of reflected light on the front and back surfaces of the sheet can be set. This creates a state in which they are mutually erased, and the occurrence of errors can be effectively prevented.

In this way, the sheet thickness output signal detected and outputted by the sensor head 26, as shown in FIG. interface 3
8 to the CPU 40, and the above-mentioned arithmetic expression (1
), the sheet thickness is calculated corresponding to each required scan position, and this is stored and statistical calculation processing is performed for graphic ink display. Therefore, the result of the arithmetic processing is displayed on the CRT display device 42.
can be displayed as appropriate. An example of graph ink displayed on the CRT display device 42 is shown in FIG. 4(a).

(As shown in bl. Figure 4 (al) indicates the current profile measurement value, and Figure 4 (b) shows the average deviation of the profile measurement results obtained by performing multiple scans. This shows that.

Moreover, FIG. 4(e) is a characteristic diagram when a plastic sheet sample exhibiting the characteristics shown in FIG. 4(a) is measured using a micrometer.

As is clear from comparing these characteristic diagrams, it will be understood that the profile measurement method according to the present invention is superior in accuracy.

FIG. 5 shows another embodiment of the method for measuring the profile of a plastic sheet according to the present invention, and is a schematic diagram of a thickness needle for carrying out this method. That is,
This embodiment is characterized in that the sheet surface temperature, which has a high correlation with the average temperature of the plastic sheet, is measured simultaneously with the profile measurement using the thickness needle, and the profile measurement error is corrected by calculation. Therefore, in this embodiment, as shown in FIG. 5, a temperature sensor 44 such as an infrared radiation thermometer is provided integrally with the sensor head 26 described above. Therefore, by measuring the temperature of the profile measurement surface of the plastic sheet,
A thickness measurement error Δy1 caused by thermal expansion of the sheet and a thickness measurement error Δy2 caused by a change in the refractive index of the sheet, each having temperature dependence, are corrected and calculated.

Therefore, let the incident angle of the light beam by the thickness needle be i, the set value of the refractive index be no, and the measured value of the thickness gauge based on the above-mentioned equation (1) in this case be yo. If the measured value of the sheet temperature at the time when the measured value of this thickness meter is obtained is Δθ, then the correct thickness y can be approximately calculated by the following equation.

y=y −△y, −△y2 , . 13) However, △3
't=α・△θ・y, (41n.

△y2=□ n, 2-sin' i ・μ・△θ・y ,, f5) In this case, α is the linear expansion coefficient, μ is the temperature coefficient of refractive index, i
is the angle of incidence of the ray.

Here, the above formula (5) is an approximate formula obtained as follows. That is, by transforming the above equation (1), the following equation is obtained.

sin 2 i If the refractive index n changes, it will affect the gap between the reflected light on the front and back surfaces of the sheet, which is directly detected by the sensor. Therefore, when the partial differential coefficient of the above equation (6) is determined, the following equation is obtained.

D si'n 2 in yaw D ,,17)+2-5i
n2i From the above equation (7), △D n □ ζ - (□) △n Dn'-5in2i ,,, (8) In the above equation (8), △D/D is the relative error of the displayed value △
)' 2 / '16, and n in ()
By setting no + ΔQm−μ·Δθ, the above formula (5) can be obtained. By the way, no-1, 4
9,1-49,2°, μ=1. When I X 10-', Δy becomes 0·yo to "GIO-'.

Profile measurement according to this embodiment configured as described above can be basically achieved by the system configuration shown in FIG. 3.

In this case, the interface 38 includes the sensor head 26
A sheet surface temperature output signal from a temperature sensor 44 is added along with a sheet thickness output signal from a temperature sensor 44 and a scan position signal from a drive motor 36 . In this way, each signal input to the interface 38 is calculated from the above calculation formula from the sheet thickness output signal and sheet surface temperature output signal at that time, each time the sensor head 26 reaches a predetermined sampling position in the CPIJ 40. (41, +5) and (3) are calculated sequentially, correct plastic sheet profile measurement data with error correction is accumulated, and C
It can be displayed on the RT display device 42. A flowchart of such processing operations in the CPU 40 is shown in FIG.

FIG. 7 shows a thickness gauge, that is, a sensor for measuring the profile of a plastic sheet according to the present invention, as described above;
FIG. 3 is an explanatory diagram showing a head control method. For convenience of explanation, the same reference numerals are given to the same components as those of the embodiment shown in FIG. 1. In FIG. 7, a pulse motor is used as a drive motor 36 for scanning the sensor head 26 in this embodiment. However,
The drive motor 36 and the sensor head 26 are connected to a calculation section 48 via a controller section 46. The controller unit 46 includes a sensor head converter 50 that converts a signal detected by the sensor head 26 into a sheet thickness output signal, a motor controller 52 that controls the drive motor 36, and a motor controller 52 that controls the drive motor 36. A motor converter 54 converts the drive signal into a scanning position signal for the sensor head 26, and the motor controller 52 is provided with speed and speed change signals.
It is comprised of a setting device 56 that sets the return position and commands these setting values. The calculation unit 48 also has an input interface 58 for inputting the sheet thickness output signal output from the sensor head converter 50 of the controller unit 46, and a scan position signal output from the motor converter 54. Input interface 60 for inputting
, an output interface 62 for supplying a control command signal to the setting device 56 , and each of the input interfaces 58 .
A CPU 6 that performs predetermined profile measurement calculations and thickness needle control calculations based on data input through the CPU 60.
4, and a display device 66 that displays the calculated profile measurement data.

Using the thickness gauge control system configured in this manner, in this embodiment, the standard scan speed and reduction speed of the sensor head 26 are set in the setting device 56.

Set the step shift position and turning point position respectively. Note that these setting values can be arbitrarily set by the CPU 64. Therefore, when setting the shift position and the turning point position, respective setting standards are determined as shown in FIG.

First, the left and right end positions "SL" of the plastic sheet S,
X5L) is the profile measurement data [Figure 4 (a)]
It can be confirmed from the sudden change position (PL, PR).

Therefore, the turning point position (xtL, The positions (xct, , , this setting device 5
6 outputs a control command to the motor controller 52.

Next, the operation of this embodiment will be explained. For example, if the sensor head 26 is moving in the direction of leaving the plastic sheet S, when the sensor head 26 reaches the shift position (xcL, XcN), the motor controller 52 is activated to change the scan speed. While the speed is automatically reduced, the CPU 64 executes profile measurement calculations and display thereof at a fine sampling pitch (for example, 1 m). Thereafter, when the sensor head 26 reaches the turning point position (X-61, XtFt), the sensor head 26 temporarily stops. After the specified downtime has elapsed,
The drive motor 36 is started again, and scanning and sampling of the sensor head 26 is started at a low speed and a fine pitch.

When the sensor head 26 reaches the speed change position (XCL,
m), and the profile measurement calculation and its display continue. During this period, the plastic sheet end position is inspected at regular intervals, and when it is determined that it has changed, the shift position (XCI-+Xc (e) and a command to update the turning point position (xtL, xtR) is output. In this case, it is preferable to configure the system to output an alarm message or signal to the operator as required. Accordingly, a flowchart for implementing such a system is as shown in FIG.

〔Effect of the invention〕

As is clear from the embodiments described above, according to the present invention,
The thickness of the sheet is calculated by measuring the distance between the reflected light from the front and back surfaces of the plastic sheet using a beam such as a laser, so the thickness of the transparent sheet, especially its Profile measurement can be achieved easily and with high accuracy. In particular, according to the present invention, by setting the direction of irradiation of the light beam on the surface of the plastic sheet and the direction of its reflection to be parallel to the sheet transport direction rather than the scanning direction of the sensor head, the direction of the light beam on the sheet surface and the sheet Errors caused by misalignment of measurement points with the back surface can be minimized, and highly accurate profile measurement can be achieved.

In addition, plastic sheets that are continuously molded are still at a high temperature when their profiles are measured, so thermal expansion and changes in refractive index can cause measurement errors that cannot be ignored, especially in the case of thick sheets. However, according to the present invention, more accurate data can be collected for profile measurement by measuring the surface temperature of the sheet at the same time as profile measurement and performing temperature function correction of thermal expansion and refractive index from this temperature measurement value. can be achieved.

Furthermore, according to the present invention, by improving the measurement accuracy using the thickness needle, it becomes possible to detect sudden changes occurring at the sheet edge during profile measurement without taking too much sampling time. The sheet width can be easily and accurately measured from the sheet edge surface and its center position.Therefore, the management and adjustment of the sheet width and profile can be performed in a well-balanced manner while considering their mutual relationship, improving sheet quality and trimming. The front seat width can also be adjusted to a minimum.In this way,
It is possible to improve product yield and reduce manufacturing costs. In addition, even in the event of an abnormality in the melt bank in the forming roll unit, it can be detected with high accuracy as an abnormality in the profile measurement data, so it is possible to output an alarm signal and prevent the occurrence of defective products. can.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and it goes without saying that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration and arrangement of a thickness needle for carrying out the method for measuring the profile of a plastic sheet according to the present invention;
Figure 2 is an explanatory diagram showing the correspondence between the sensor head of the thickness gauge and the plastic sheet, Figure 3 is a block diagram of the arrangement of the thickness needle and the measurement calculation circuit shown in Figure 1, and Figure 4 (a).
). (bl, (C1 shows the profile characteristics measured by the measurement method of the present invention, FIG. 4 (al shows the current profile characteristic diagram, FIG. Figure, Figure 4 (C)
is a profile characteristic diagram measured by a micrometer of a sample exhibiting the characteristics shown in FIG. FIG. 6 is a flowchart for performing profile measurement using the thickness gauge shown in FIG. Control system diagram, Fig. 8 is a scan speed characteristic diagram of the thickness needle controlled by the control system shown in Fig. 7, and Fig. 9 is a diagram showing the profile measurement and its scan speed control shown in Figs. 7 and 8. Flow chart diagram for execution, 1st
Figure 0 is a diagram of the thickness measurement principle of the thickness needle applicable to the present invention, Part 1
Figure 1 is a schematic diagram showing the plastic sheet molding process, Figure 12 is a schematic diagram showing the configuration and arrangement of a thickness gauge commonly used for measuring the profile of plastic sheets, and Figure 13 is a diagram showing the neck of the sheet in the plastic sheet molding process. It is an explanatory view showing an in phenomenon and a trimming process. 10. Extruder 12. , Sheet forming square bottom die 14 , Forming roll unit 16 , Scanning thickness needle 18 , Protective paper supply unit 20 , Take-up roll unit 22 , Sheet cutting fi 24. ,,sheet loading machine 26,,,sensor head 28. ,,frame 30
, , , rail 32. ,,Pulley 34,,
, endless belt 36. ,, Drive motor 38, , Inter 7e X 40. , CPU 42 , CRT display device 44 , Temperature sensor 46. ,,controller section 48,,,calculation section 50. ,, sensor head converter 52, , motor controller 54. ,, Motor converter 56, Speed and speed change/folding black film regulator 5B,...
Input interface 60, , input interface 62, , output ink 7 ace 64 . ,, CPU66
,,, Display device patent applicant Toshiba Machine Co., Ltd. FIG, 1 FIG, 4 FIG, 5 FIG, 6 FIG, 7 FIo 9 FIG, 10 Δ× FIG, 11

Claims (6)

[Claims] (1) A sensor head is provided, which includes a light source such as a laser that irradiates the surface of a plastic sheet at a required angle of incidence, and a sensor that detects the distance between the reflected light reflected from the front and back surfaces of the sheet. The sheet thickness is measured by setting the head so that the direction of incident light and reflected light on the continuously molded plastic sheet is parallel to the conveying direction of the sheet or the opposite direction thereof, and moving the head back and forth in the width direction of the sheet. A method for measuring the profile of a plastic sheet. (2) The sensor head is equipped with a temperature sensor that measures the surface temperature of the plastic sheet, and the temperature measurement value is used to perform correction calculations for sheet thickness errors caused by thermal expansion of the sheet and changes in the refractive index of light. The method for measuring the profile of a plastic sheet according to claim 1. (3) Using the seat edge detected by the profile measurement data as a reference, set the shift position and its speed below the standard speed on the inside thereof, set the turning point position on the outside of the seat edge, and set these 3. The plastic sheet profile measuring method according to claim 1, wherein the reciprocating movement of the sensor head is controlled based on a set value to measure the sheet width of the continuously molded plastic sheet. (4) A sensor head is provided that includes a light source such as a laser that irradiates the surface of the plastic sheet at a required angle of incidence, and a sensor that detects the distance between the reflected light reflected from the front and back surfaces of the sheet, and this sensor The head is set so that the direction of incident light and reflected light on the continuously molded plastic sheet is parallel to the transport direction of the sheet or the opposite direction thereof, and the head is suspended on a frame so as to be movable back and forth in the width direction of the sheet, A computing unit that is provided with a drive motor that controls the reciprocating movement of the sensor head, and that performs profile measurement by inputting a sheet thickness output signal detected by the sensor head and a scan position signal detected from a control system of the drive motor, respectively. A plastic sheet profile measuring device comprising: (5) The sensor head is equipped with a radiation thermometer that measures the surface temperature of the plastic sheet, and the temperature signal measured by this radiation thermometer is input together with the sheet thickness output signal and the scan position signal to determine thermal expansion and light. 2. The plastic sheet profile measuring device according to claim 1, further comprising a computing unit for correcting sheet thickness errors due to changes in refractive index to measure the profile appropriately. (6) A motor controller is provided for the drive motor that controls the reciprocating movement of the sensor head, and a setting device that sets the sensor head speed, shift position, and turning point position, and a setting device that sets the sensor head scan position for the motor controller. A converter that detects the position and outputs the position signal is provided, and the set value to the setting device is calculated based on the sheet edge detected by the profile measurement data measured by the sensor head, and the plastic is continuously molded. 3. The plastic sheet profile measuring device according to claim 1, further comprising a computing unit for measuring the sheet width of the sheet.