JPS5933092B2 - Film thickness adjustment method - Google Patents

Description

Detailed Description of the Invention: In an apparatus for producing unstretched films and sheets, uniaxially oriented films and sheets, or biaxially oriented films from molten polymeric materials, films and sheets extruded from various die shapes are used. In the past, when adjusting the deflection in the width direction, the adjustment work was generally done manually.

However, this work requires a high degree of skill, and since it is done manually, there are limits to the final deflection adjustment accuracy. Furthermore, since the working environment was poor, there was a strong desire to put an automatic deflection adjustment device into practical use. Although various automatic film deflection adjustment devices have been proposed in the past, they are still insufficient for practical use and are not used much.

That is, in order for an automatic adjustment device to be adopted, it goes without saying that it must take a shorter time than the conventional manual adjustment time and must also have superior final deviation accuracy. To this end, the most important point is not only the automatic adjustment device, but also the establishment of a control method. Conventionally, JP-A-52-
A method shown in Japanese Patent Publication No. 36154 has been proposed, in which when an automatic adjustment device is used as an adjustment method, if thickness adjustment is performed at many locations at once, the thickness distribution of the entire film will be affected and the thickness adjustment will be difficult. If there are many parts where the thickness deviation exceeds the allowable range, it is necessary to adjust only the part where the thickness deviation is the largest and gradually improve the overall width direction thickness distribution. If adjusting one location at a time slows down the convergence to the desired thickness distribution,
It is said that it is better to select 2 to 3 locations in descending order of thickness deviation and make adjustments, but this method is similar in concept to manual operation, and rather takes a long time to make corrections. There are drawbacks. The present invention was proposed to solve the above-mentioned conventional drawbacks, and when the deviation in thickness distribution is large, the number of bolts to be operated is limited, and when the deviation is small, nearly all the bolts are operated. It is an object of the present invention to provide a film thickness adjustment method that can shorten correction time and improve deflection accuracy by operating the film.

The present invention will be explained below with reference to the embodiments shown in the drawings. Figures 1, 2, and 3 show an unstretched film and sheet manufacturing apparatus, a uniaxially oriented film and sheet manufacturing apparatus, and Figure 4 is a plan view of the biaxially stretched film manufacturing device, and Figure 4 is a cross-sectional view of the bolt automatic adjustment device and die, which are installed in the middle of the die flow path or at the outlet in order to mold the molten polymer material into the desired shape. The purpose is to automatically adjust the widthwise thickness distribution of the sheet or film by automatically operating the gap adjustment bolt of the lip with an automatic bolt adjustment device.

Now, in the manufacturing process of the various films and sheets shown in the drawings, the thickness in the width direction is measured by each thickness measuring device 1, and the thickness deviation with respect to the set value corresponding to the die adjustment bolt 3 is calculated by the calculator 2, Based on the deviation, the amount of operation of each adjustment bolt 3 is calculated using a predetermined method.

In addition, the bolt 3 is rotated by a predetermined amount by the bolt automatic adjustment device 4, and as a result, the die adjustment lip 5 is deformed to adjust the extrusion amount corresponding to the bolt, thereby correcting the uneven thickness, and measuring the result. Measurement is performed using the device 1, and the same operation is repeated until the desired film width direction profile is finally converged. When disassembling and reassembling the die 6, or when changing the thickness of the product, adjusting the resin passage gap of the adjusting lip 5, or changing the extrusion amount per width of the die 6, deviations may occur at the start of production. Generally, you have to start with very poor meat accuracy.

In this way, when adjusting from a situation with poor thickness unevenness accuracy to converge to the tolerance range for the target profile, the quality of automatic adjustment equipment depends on how quickly and highly accurate products can be manufactured. be. In the figure, 7 is a cooling roll group, 8 is a longitudinal stretching machine, 9 is a horizontal stretching machine, and 10 is a winding device. In addition, conventionally, due to problems such as the flow inside the die 6 or the deformation of the adjustment lip 5 due to bolt operation, 1.
It was difficult to converge to the desired profile by adjusting the bolts several times, and it was necessary to converge to a certain extent by trial and error.

That is, the present applicant previously submitted Japanese Patent Application No. 135743/1983, in which the thickness deviation in the width direction is continuously measured every 1111 pitches, and the positions corresponding to the adjustment bolts are measured by a computer.
Integrate the thickness and calculate the deviation from the target profile for each bolt. Calculate the amount of rotation of each bolt using a predetermined formula based on the deviation. Move the adjustment device to the i-th bolt position. We have proposed a control method in which the bolt is controlled by a calculated amount of rotation using a pulse transmitter and a computer, but with this method, even if the adjustment is based on the deviation, ideally it is adjusted only once (for each bolt in the width direction). Currently, it is impossible to reach the desired profile using the following methods, and one must rely on trial and error. In order to shorten the convergence time T, the biggest problem is how to reduce the number of adjustments n and how to shorten the bolt operation time. According to experiments conducted by the present inventors, it has been found that limiting the number of bolt operations increases the number of adjustments n, and it takes a long time for convergence.

However, even if all the bolts are operated when the thickness deviation accuracy is poor, such as at the start of production, the deviation may be in the opposite direction to the operating direction in places where the deviation was originally small, and as a result, the adjustment becomes meaningless. It is not a good idea to unnecessarily lengthen the bolt operation time t1. Therefore, when the deviation is large, limiting the number of bolts to be operated will actually save time. Furthermore, if the overall deviation becomes small to a certain extent, the number of convergence n will increase unless nearly all the bolts are operated. As explained in detail above, the present invention is configured such that when the deviation is large, the number of bolts to be operated is limited, for example to about 1/2, and when the deviation becomes small, nearly all the bolts are operated. As a result, the operation time for convergence can be shortened.

Next, based on specific examples of the relationship between the profile and the film width direction according to the conventional method shown in FIG. Explain that there are

Note that the numerical values in FIGS. 5 and 6 indicate the percentage deviation from the target profile at the position corresponding to each bolt. In addition, although the diagrams are shown with two lines in FIGS. 5 and 6, the thickness measuring device reciprocates in the film width direction in a direction perpendicular to the film running direction, so that the outward and return passes can be measured. The measurement results are shown as two lines. First, in the conventional method shown in Fig. 5 A, C, and C, the die width is 762 mm, the extrusion amount is 2001<9/Hrl, the number of bolts is 16, and the position of the thickness measuring device is uniaxial stretching in Fig. 2. After that, the number of bolts to be operated was limited to eight in descending order of the deviation corresponding to the bolt, and the results shown in Figure 5 A, C and C were obtained.

In addition, FIG. 5A is the pattern at the start of production, the opening is the pattern after the 6th adjustment, and C is the pattern after the 12th adjustment (50 minutes after the start of production). Next, in the method of the present invention shown in Fig. 6 A and C, the die width is 762 m7! L, extrusion amount 200
1<9/Hrl The number of bolts is 16, the position of the thickness measuring device is after uniaxial stretching as shown in Figure 2, and the number of bolts to be operated is 8 when the maximum value of the deviation corresponding to the bolt is 3% or more, 3 % or less, when the total number was operated, the results shown in Figures 6A and 6C were obtained, and the results were far superior to those shown in Figure 5.

In addition, A in Figure 6 is the pattern at the start of production, the opening is the pattern after the second adjustment (all operations are performed from now on), and C is the pattern after the seventh adjustment (
35 minutes after the start of production) This is the pattern after adjustment.

[Brief explanation of drawings]

1, 2, and 3 are plan views showing an unstretched film and sheet manufacturing apparatus, a uniaxially oriented film and sheet manufacturing apparatus, and a biaxially oriented film manufacturing apparatus, respectively, showing examples of the method of the present invention; Figure 4 is a sectional view showing the bolt automatic adjustment device and the die, Figures 5A and 5C are line diagrams showing the relationship between the film width direction and the profile in the conventional film thickness adjustment method, and Figure 6I. , , C are diagrams showing the relationship between the film width direction and the profile in the method of the present invention. Explanation of the main parts of the diagram, 1... Thickness measuring device, 2...
...Arithmetic unit, 3...Die adjustment bolt, 4.
...Bolt automatic adjustment device, 5 ...Die adjustment lip, 6 ...Die.

Claims (1)

[Claims] 1. In order to mold the molten polymer material into the desired shape, the lip gap adjustment bolts provided in the middle of the die flow path or at the exit are automatically operated to adjust the thickness distribution in the width direction of the sheet or film. The film thickness adjustment method is characterized in that when the deviation in the thickness distribution is large, the number of bolts to be operated is limited, and when the deviation is small, the number of bolts to be operated is operated close to the full number. Method.