JPS5857298B2 - How to wind the film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for winding a continuously running film into a roll.

Generally, when a synthetic resin film is continuously formed by extrusion molding or the like, it is extremely important to make the thickness of the film uniform; It is not possible to make a film formed through stretching, etc.) to have a completely uniform thickness, and it is inevitable that fine thickness unevenness will occur.

When a film with such a deflection is wound into a roll on a take-up shaft, the deflection accumulates on each take-up roll, resulting in bulges, etc., and in extreme cases, the film may become sagging or wrinkled. Become.

Conventionally, due to such uneven thickness of the film, in order to prevent the occurrence of defects in the winding appearance, there has been a method of winding the film while causing a relative oscillation motion between the continuously running film and the winding shaft. As it has been adopted, it has had a considerable effect.

However, in this conventional method, most of the oscillation operations are performed manually, making it difficult to grasp the optimal oscillation conditions.

Therefore, it is difficult to change and adjust the oscillation conditions without following the width direction thickness distribution of the film, which changes over time.

The present invention provides a film winding method that improves the above-mentioned conventional drawbacks, in which the width direction thickness profile of a continuously running film is measured, and the obtained winding roll is measured from the thickness profile. The oscillation conditions that will give the best shape are calculated online, and the resulting oscillation conditions are fed back to the oscillation control end of the winding shaft, ensuring that the film is always wound under the best conditions. It is something.

The present invention will be explained in detail below.

FIG. 1 is a schematic plan view showing an apparatus for carrying out the method of the invention.

1 is a film running in the direction of the arrow, 2 is a rotating winding shaft for winding up the film 1, and 5 is a film wound on this shaft 2! It is a tori roll.

Reference numeral 3 denotes a thickness measuring device for measuring the thickness profile in the width direction of the film 1, and a conventional device using β-rays, X-rays, ultraviolet rays, etc. is used.

This thickness measuring device 3 measures the thickness profile of the film 1 in the width direction while scanning in the width direction of the film 1 using the scanning device 31Vc, and the measured value obtained as a result is transmitted to the input transducer 6.
5 and stored in the storage device 62.

4 is a trimming device, which trims the film 1 by a driving device 41;
It is possible to move towards the mountain.

21 C. An oscillation operating device for oscillating the take-up shaft 2 in the direction of one film.

As mentioned above, the purpose of the present invention is to control the winding conditions of the film so that the shape of the winding roll 5 is optimal. Noting that there is a certain correlation with the shape of the roll 5, the shape of the take-up roll 5 is calculated from the thickness profile in the width direction of the film 1 measured by the thickness measuring device 3.

According to this method, a special device for directly measuring the shape of the rotating take-up roll 5 is not required.

The method for calculating the shape of the take-up roll 5 will be explained based on Table 1 below. .3...
... indicates the width direction position of the film 1.

), and the winding shaft 2 has an oscillation time To, an oscillation both-ends stop time Ts, and an oscillation width (1/1 of the actual moving distance).
2) If it is oscillated at 2d, then 1, for example, i = 1 to 5.
The relative movement of the film with respect to the winding shaft 2 is shown in Table 1.

If we find the film stacking average thickness (in other words, the roll shape) Y5 at the position in the width direction of the case take-up roll at =5, we get: .

Xi: Measured thickness in the width direction of the film 1 m: Oscillation width/Measurement interval of the thickness in the width direction of the film.

T.

α: , 'l'o: Oscillation time, TsNioTo1Ts Syllate both ends stopping time, i: Thickness measurement position in the width direction of the film (i=1.2, 3..., n)k: Width direction position on the take-up roll (k=2m+1.2m+2゜...
..., n)].

As described above, the thickness is measured by the thickness measuring device 3 and stored in the storage device 62.
The width direction thickness profile of the film 1 stored in is moving averaged by the arithmetic unit 63 to obtain the take-up roll shape.As is clear from the above equation (1), the take-up roll shape is determined by becomes a function of

Then, from the thickness profile and the take-up roll shape, the optimal m and α are calculated by the process illustrated below.

That is, the deviation between the desired take-up roll shape and the ideal take-up roll shape (i.e., a smooth roll shape with an equal outer diameter at all positions).

At the width direction position on the take-up roll = 2m + 1, 2m + 2...
. . . and the arithmetic unit 63 calculates m and α that minimize the standard deviation.

The calculated mk + α is sent to the oscillation operating device 21 via the output converter 67, and the winding shaft 2 is oscillated.

Here, there may be equipment limitations on the oscillation width, but in that case, optimal conditions are selected under the actual limitations.

As the oscillation width (in other words, m) is increased, the appearance of the winding gradually improves, but when the oscillation width exceeds a certain limit, the degree of improvement in the appearance of the winding decreases, and no further effect can be expected.

Therefore, it is best to select the minimum oscillation width at which the degree of improvement in the winding appearance begins to level out.

In order to find the optimum oscillation conditions, we will explain below a method that can better follow changes in the width direction profile.

Assuming that the thickness profile in the width direction of the housing film 1 can be approximated by a periodic function, the thickness measurement values Xi sequentially obtained by measuring the profile with the thickness measuring device 3 that scans the width direction of the film 1 will change over time. It can be thought of as a vibrating input.

Therefore, if the output obtained by passing this oscillating input through a moving average calculation system called oscillation (that is, the shape of the winding roll) is measured by scanning it in the width direction, it will be measured over time at the same period as the thickness profile. It will vibrate twice.

Optimizing the shape of the winding roll, which is the output, means minimizing the amplitude 1 of the output for a given input.

In other words, the problem can be replaced with the problem of minimizing the oscillation rate, which is the kein (amplitude of output/amplitude of input) of a moving average calculation system.

Therefore, based on the above idea, we derive the gain of a moving average calculation system called oscillation by considering the thickness profile in the width direction of the film as a periodic function, and calculate and apply oscillation conditions that minimize this gain under actual limiting conditions. It was confirmed that an extremely good take-up roll shape could be obtained in practice.

From the above equation (1), a moving average calculation system called oscillation 1
The gain G of is derived as follows.

Here, e is the wavelength when the width direction thickness profile of the film is approximated by a periodic function, and the film thickness measurement interval d
It is the value divided by

The arithmetic unit 63 calculates m and α that minimize the gain G derived in this way under actual limiting conditions, and the output converter 67 converts the calculated m and α into electrical signals. This is fed back to the oscillation operating device 21 to oscillate the first winding shaft 2.

At this time, the trimming device 4 is also oscillated by the m and α signals.

For this purpose, the speed detector 7 detects the running speed of the film 1, and the detected value is sent to the input converter 64 to the arithmetic unit 63.
The time delay between when film 1 is trimmed and when film 1 is wound is calculated.

The end face of one take-up roll 5 is then delayed by giving the signal sent to the drive device 41 of the trimming device 4 through the output converter 66 and the signal sent to the oscillator operating device 21 through the output converter 67. It can be flattened.

As for the thickness profile in the width direction of the film 1, it is preferable to take the average value of the measured values obtained by reciprocating the thickness measuring device several times.

Since this thickness profile in the width direction changes over time due to variations in film manufacturing conditions and film thickness adjustment operations, new data is sequentially sent to the storage device 62 while constantly being measured by the thickness measuring device 3.

This makes it possible to always wind the film under the best conditions while following the ever-changing thickness profile in the width direction of the film.

When approximating the thickness profile in the width direction of the casing with a periodic function, it is easiest if it can be approximated with one function, but if a sufficiently good approximation cannot be obtained, it may be approximated with a composite function of several functions.

The approximation of the thickness profile in the width direction of the casing to a periodic function can be performed by simulating the thickness profile with the calculation device 63, but as a simpler method, it is possible to approximate the thickness profile in the width direction to a periodic function. The position of the deflection part (that is, the part where the deflection exceeds the thickness tolerance set by a certain standard) is detected by an appropriate means, and the average distance between the uneven thickness parts is taken as the wavelength e-d of the approximate periodic function. You can also do that.

(For example, if a film with a width of 1 m has five uneven thickness parts that are a particular problem at approximately equal intervals, then ed = 20 cm.

) According to the method of the present invention, the thickness changes over time (while detecting the thickness profile in the width direction of the film).

By following this and calculating and applying the optimum oscillation conditions, the film can always be wound under the optimum conditions, and a winding roll with an extremely good appearance can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view showing an apparatus for carrying out the method of the present invention. DESCRIPTION OF SYMBOLS 1... Running film, 2... Winding shaft, 21... Oscillating operating device (oscillating operating end), 3... Thickness measuring device, 5... Winding roll, 63... Calculation Device.

Claims (1)

[Claims] 1. In a method of winding a continuously running film into a roll on a winding shaft that oscillates the film in the width direction, the thickness profile of the film in the width direction is measured, and (B
) The shape of the take-up roll when the take-up shaft is oscillated with respect to the film is determined by the film lamination average thickness obtained by moving the average of the thickness profile. (Q Calculate the ratio of the oscillation width, oscillation time, and oscillation stop time at both ends so that the deviation between the desired take-up roll shape and the ideal roll shape is minimized.) ■ The calculated oscillation width, oscillation time, and oscillation rate. A film winding method characterized in that the ratio between the stop time at both ends is fed back to the oscillating operation end of the winding shaft. 2. A film winding method characterized in that the ratio between the stop time at both ends is fed back to the oscillating operation end of the winding shaft. In the method of winding the film into a roll.B) Measure the thickness profile of the film in the width direction.
The take-up roll shape when the take-up shaft is oscillated with respect to the film is determined by the moving average film lamination average thickness of the thickness profile, (Q) the above thickness profile is input, the roll shape is output, and the above The gain of the moving average calculation system is derived by approximating the thickness profile with a periodic function, and the oscillation width and the ratio of the oscillation time to the oscillation stop time at both ends are calculated so that the gain is minimized. ■ Calculation A film winding method characterized in that the oscillation width and the ratio between the oscillation time and the oscillation both-end stop time are fed back to the oscillation operation end of the winding shaft.