JPH0649325B2 - Film thickness control method for strips - Google Patents

Description

TECHNICAL FIELD The present invention relates to a film thickness control method for forming a belt-shaped material such as a thermoplastic plastic film or sheet.

(Prior Art) An outline of the conventional molding process of a thermoplastic sheet will be described with reference to FIGS. 6 to 9. First, referring to FIG. 6, the operation part 28 such as a die operation bolt or a heater (not shown) of the die 9 is operated by the output of the film thickness control device 27 to adjust the slit of the die 9 to the thermoplastic resin. Is extruded, and after passing through a cooling and solidifying device 10 constituted by a roll group to form a sheet, the thickness is measured by a thickness measuring device 11 for cast sheet, and the obtained sheet progresses the sheet. The film is passed through a vertical stretching machine 12 including a group of rolls for longitudinal stretching in the direction. Next, the longitudinally stretched sheet is
As shown in FIG. 7, both ends 18 and 19 are held by clips 16 and 17 by a transverse stretching machine 13 and formed into a film which is transversely stretched in a direction orthogonal to the sheet traveling direction while being heated. After measuring the thickness with the thickness measuring device 14 for use, the both ends l ₁ and l ₂ are slit and separated, and then the winder.
Winded up at 15.

Next, the thickness profile necessary for controlling the film thickness will be described. In the film thickness control, by the cast sheet and product thickness measuring devices 11 and 14, the lateral thickness profile of the entire film width becomes a predetermined predetermined (for example, uniform thickness) profile, The operation amount is calculated by the film thickness control device 27 to the slit part of the die 9, and the result is fed back to the operation part 28 of the die 9. The shape of the thickness profile in the film thickness control at this time is grasped. The thickness profile of the cast sheet thickness measuring device 11 after passing through the cooling and solidifying device 10 (FIG. 8A), and the product thickness measuring device 14 after passing through the transverse stretching machine 13
It is controlled by the cross-sectional area ratio between the thickness profile (Fig. 8 (b)). Here, as shown in FIG. 8 (a), the edges 18, 19 of the sheet are thicker than the central portion until the sheet is extruded from the die 9 and then cooled and solidified to be formed into a sheet. In order to prevent the resin at the end from contracting and moving toward the central part due to the necking effect, and to prevent the film from being detached from the clips 16 and 17 during the transverse stretching in the transverse stretching machine 13. , This may be because the thickness of both ends is set thick.

Further, the same tendency is shown in FIG. 8 (b) because the sheet ends 18, 19 are clipped as shown in FIG. Because it is low. Normally, the thickness of both ends is about 10 times the thickness of the center (if the center is 20 μm, the thickness of both ends is about 200 μm).

(Problems to be Solved by the Invention) In a conventional thickness measuring device such as a thermoplastic sheet, it is necessary to accurately measure the thickness of the central portion which is actually wound by a winder and adopted as a product. Since it was the main focus, the measurement range was exceeded at both ends, and the measured values were saturated, and accurate values could not be obtained. Therefore, conventionally, only the measurable range w is measured as shown in FIG. 7, and the data of the unmeasurable ranges l ₁ and l ₂ are measured by the operator bringing the film into the measuring room and performing the OFF LINE measurement. The average thickness data 20 and 21 within the obtained measurement range were input from the film thickness control device 27 that inputs the setting data for forming control, and the thickness data for film thickness control was obtained.

The thickness profile of the film end l ₃ by conventional methods, because it uses a ninth diagram (a) (b) are shown (one end portion only) unmeasurable range of the average thickness data 20 and 21, for example, In the case of the profile shown in FIG. 9 (a), the error between the profile shape and the average thickness is small, but FIG. 9 (b)
In the case of the profile (1), there is a problem in control such that the error becomes very large depending on the measuring position and the positional recognition of the thickness profile is misaligned. In addition, if the end thickness profile changes due to changes in operating conditions, it is necessary to re-measure in the measurement room, and it is not possible to immediately respond to dynamic changes in the profile. However, much effort and time was spent.

An object of the present invention is to provide a method for controlling the film thickness of a strip, which measures an edge thickness profile by a simple procedure and enables accurate control without depending on the profile shape.

(Means for Solving the Problems) Therefore, in the present invention, control is performed by combining thickness profile data obtained by measuring a thermoplastic film, sheet, or the like with a thickness measuring device and various preset film thickness control setting data. In the film thickness control method for strips, the edge thickness profile data in the specified range is extracted from the thickness profile data measured by the thickness measuring device for thickness before the film thickness control, and this data is used to control the thickness for thin products. The thickness profile data measured by the measuring device is superposed and combined into the thickness profile data of the full width, and the film thickness is controlled by the profile data, which is a means for solving the problem. .

The present invention also provides a method for controlling the film thickness of a strip in which the thickness profile data obtained by measuring a thermoplastic film, a sheet or the like with a thickness measuring device and the preset data for various film thickness control settings are controlled together. Edge thickness profile data in the specified range was extracted from the thickness profile data measured by the thickness measurement device that was switched to the thickness measurement wavelength before thickness control, and this data was used to switch the thickness measurement wavelength to the thin thickness measurement wavelength. The thickness profile data measured by the measuring device is superposed and combined into the thickness profile data of the full width, and the film thickness is controlled by the profile data, which is a means for solving the problem. .

(Function) For a film that cannot be accurately measured by the measurement sensor for measuring the central part of the thickness measuring device, for thin objects for measuring the central part and for thick objects for measuring both ends A thickness measuring device equipped with both measuring sensors is used, and the thicknesses of the two film full widths measured by switching between these two sensors are taken into consideration by considering the effective measurement range of each sensor. , And the data for the adopted width of each sensor is extracted from the above two sets of data and combined, whereby accurate thickness profile data for the entire width of the film can be obtained.

Further, in the above description, the thickness data for the two widths of the film are the thicknesses provided with both the wavelength range for thin object measurement for measuring the central part and the thickness range for measuring thin objects for measuring both end parts. It can also be obtained by using a measuring device and switching between these two wavelength ranges for measurement.

(Embodiment) The present invention will be described below with reference to embodiments of the drawings, and FIGS. 1 to 4 show an embodiment of the present invention. Now, in the first step of FIG. 1, first, in order to be able to measure the edge thickness data for the film after transverse stretching, the thickness measuring sensor for thin object 1a of the thickness measuring device for product 1 is used to measure the thickness for thick objects. Switch to sensor 1b. The product thickness measuring device 1 is then scanned laterally over the entire width of the film and the second
The thickness profile data 22 shown in the figure is transferred to the buffer A23 in the storage unit 5 by the calculation unit 4 via the thickness data input unit 3.
To store. When inputting the thickness data, (EIA R
Communication means (S-232C, RS-422A, etc.) may be used, or A / D
It may be an analog input using a converter.

Further, since the position data can be added from the data input unit 3 together with the thickness data from the product thickness measuring device 1, the thickness data 22 for the entire width of the input film has a one-to-one correspondence with the measurement position. It is stored in the captured form. The stored thickness data is simultaneously transferred to and displayed on the display unit 6 by the calculation unit 4. The operator displays the display 6
Areas measurable by the thickness measuring sensor for thick materials 1b by reading the shape of the thickness profile displayed on the screen and the scale on the scale below it (distances l ₄ and l ₅ from the film edge) Is input from the setting data input unit 7 and stored in the storage unit 5. Thereafter range l ₄ a worker in the arithmetic unit 4 is designated, l ₅ calculates whether corresponding to any part of the thickness data stored in the buffer A23. The air layer and the film layer boundaries 22a, 22b, since computationally distinguishable, data 23a included from the boundary to the specified range l _4, l _5, may be extracted 23b.

Next, the second step will be described. First, in order to measure the central portion thickness data, the thickness measurement sensor 1b for the thick product of the product thickness measurement device 1 is switched to the thickness sensor 1a for the thin product. Next, in the same manner as in the first step, the thickness profile data 24 shown in FIG.
Store in 25. Similar to the buffer A23, the thickness data is stored in a one-to-one correspondence with the measurement position.

The range designated by the first step to a buffer B25 l _4, l ₅ data 23a, 23b were transferred from the buffer A23 in the buffer B25, by overwriting data 25a, in the area of the 25b, the buffer B25 Therefore, accurate thickness profile measurement data without saturation is stored over the entire width of the film. This newly created buffer B
Since the thickness data of 25 is displayed on the display unit 6 at the same time,
The operator can correctly recognize the thickness profile 26 of the entire width of the film as shown in FIG.

Further, in the film thickness control calculation, in parallel with the second step, the cast sheet thickness measuring device 11 after passing through the cooling and solidifying device 11
Thickness profile (FIG. 8 (a)) is measured, and the thickness data stored in an area different from any of the buffers and the thickness data stored in the buffer B25 created in the second step are used. The area ratio corresponding to the position of each operation part (not shown) of the die is calculated as in the conventional case. The output unit 8 of the film thickness control device 2 can control the shape of the thickness profile by instructing each operation unit of the die of the control amount obtained by this calculation.

Further, in the second embodiment of FIG. 5, in the first step described above, the thin product thickness measuring sensor 1a of the product thickness measuring device 1 is used.
Is switched to the thickness measurement sensor 1b for thick material, and the wavelength range 29a for thin material measurement of the thickness measurement sensor 29c in the product thickness measurement device 29 is switched to the wavelength range 29b for thickness measurement,
In the second step, the thickness measuring sensor 1b for thick products of the product thickness measuring device 1 is switched to the thickness measuring sensor 1a for thin products,
Even if the wavelength range 29b for measuring the thickness of the thickness measurement sensor 29c in the thickness measuring device 29 for products is switched to the wavelength range 29a for measuring the thickness of the product, similar film thickness control can be realized.

(Effects of the Invention) Since the present invention is configured as described in detail above,
Unlike the conventional measuring method, there is no defect such as the profile shape of the film edge being unrecognizable. That is, according to the present invention, the profile shape can be accurately recognized over the entire width of the film. This improves the film thickness control accuracy. In the conventional measurement method, it took about 20 minutes for the operator to measure the thickness of the film edge at multiple points OFF LINE in the measurement room and to determine the average thickness data from the measurement data of this edge. . However, since the film manufacturing process continues to operate during this period, the resin raw materials and the like are continuously consumed. However, according to the method of the present invention, since the operation can be performed only by a simple operation from the display unit and the setting input unit, the working time can be shortened within 5 minutes, and this economic effect (the resin raw material cost per hour is several (100,000 yen) is extremely large.

[Brief description of drawings]

FIG. 1 is a block diagram of a film thickness control device for a strip showing a first embodiment of the present invention, and FIGS. 2, 3, and 4 show the relationship between the thickness profile and the buffer stored in the present invention. FIG. 5 is a block diagram of a film thickness control device for a belt-shaped product showing a second embodiment of the present invention, FIG. 6 is a manufacturing process diagram of a conventional plastic film, and FIG. 7 is a film end portion by a clip. FIG. 8 (a) is a diagram showing the thickness profile of the sheet after passing through the conventional cooling and solidifying device, and FIG. 8 (b) is a line showing the thickness profile of the film after passing through the transverse stretching machine. FIG. 9 (a) is a diagram showing the edge profile of the film (small error), and FIG. 9 (b) is a diagram showing the edge profile of the film (large error). Description of main parts of the figure 1 …… Thickness measuring device for products 1a …… Thickness measuring sensor (for thin objects) 1b …… Thickness measuring sensor (for thick objects) 2 …… Film thickness control device 3 …… Thickness and position data input Part 4 Calculation unit 5 Memory unit 6 Display unit 7 Setting data input unit 8 Output unit 11 Cast sheet thickness measuring device

Claims (2)

[Claims] 1. Thickness profile data obtained by measuring a thermoplastic film, sheet or the like with a thickness measuring device,
In the film thickness control method for strips that is controlled in combination with the preset film thickness control setting data, the edge thickness within the range specified from the thickness profile data measured by the thickness measuring device before the film thickness control. The feature is that profile data is extracted, and the thickness profile data measured by the thickness measuring device for thin objects is superposed on this data to synthesize thickness profile data of the full width, and the film thickness is controlled by the profile data. A method for controlling the film thickness of a strip. 2. Thickness profile data obtained by measuring a thermoplastic film, sheet or the like with a thickness measuring device,
In the film thickness control method of the strip that performs control in combination with the setting data for various film thickness control input in advance, it was designated from the thickness profile data measured by the thickness measuring device switched to the wavelength for thickness measurement before the film thickness control. The thickness profile data at the edge of the range is extracted, and the thickness profile data measured by the thickness measuring device switched to the wavelength for thin film measurement at the time of film thickness control is overlaid and combined into the full width thickness profile data. A method for controlling the film thickness of a strip, which is characterized in that the film thickness is controlled by means of.