JP2576252B2 - Sheet material thickness control method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for controlling the thickness of a continuously formed strip-shaped sheet material such as a plastic sheet, a nonwoven fabric, a paper, and a resin-releasing release sheet. .

(Prior Art) The thickness control method for this type of sheet material is, for example, as follows.
It is disclosed in Japanese Patent Publication No. 1-481818. In this known thickness control method, first, the thickness of the formed sheet material is measured by a thickness gauge. This measurement is performed while reciprocating the thickness gauge in the width direction of the sheet material. This is performed by sampling the thickness of the sheet material at predetermined intervals, for example, at time intervals. Therefore, according to such a sampling measurement, in the process in which the thickness gauge is displaced from one side edge to the other side edge of the sheet material, the sheet thickness is measured based on the thickness measurement data obtained in this process. A thickness distribution (usually called a profile) in the width direction of the material can be obtained, and an average thickness in the width direction of the sheet material can be calculated from the thickness distribution.

Then, the average thickness thus obtained is compared with the target thickness of the sheet material, and based on a deviation between them,
The thickness of the sheet material is controlled.

(Problems to be Solved by the Invention) By the way, in forming a belt-shaped sheet material,
The weight per unit area of the sheet material, that is, the basis weight must be made uniform. However, it is difficult to uniformly control the basis weight of the sheet material by the above-mentioned known thickness control method. That is, the measurement data of the sheet material sampled by the thickness gauge is obtained by reciprocating the thickness gauge in the width direction of the continuously running sheet material. The thickness distribution based on the thickness distribution merely indicates the thickness distribution in one movement locus of the thickness gauge in the sheet material. For this reason, even if there is local thickness unevenness in the movement trajectory of the thickness gauge with respect to the sheet material, that is, at a portion deviating from the thickness measurement line of the sheet material by the thickness gauge, the thickness of this uneven portion is Since the thickness is not included in the measurement data described above, it is difficult to make the basis weight of the sheet material uniform even if the thickness of the sheet material to be formed is controlled based on the average thickness. In addition, there is a possibility that variation in the basis weight is further promoted.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sheet material thickness control method capable of making the weight per unit area of a sheet and a material uniform. It is in.

(Means for Solving the Problems) According to the present invention, a sheet material is continuously displaced in the width direction of a sheet material while the thickness of the sheet material is continuously formed and travels. The thickness of the sheet material is sampled and measured at predetermined intervals, and based on the measured data, the thickness of the sheet material to be formed is controlled in a sheet material thickness control method. A reciprocating motion obtained by combining a small reciprocating displacement having a first amplitude and a first cycle in the width direction and a large reciprocating displacement having a second amplitude and a second cycle larger than the first amplitude and the first cycle, respectively. While giving, the measurement data is sampled by the thickness gauge, and the average weight per predetermined area in the predetermined section of the sheet material is calculated from the measurement data, and the calculated weight is used as the target weight. To match Will be in control.

(Function) According to the sheet material thickness control method of the present invention, the thickness gauge is larger than the above-mentioned reciprocating motion, that is, while being reciprocally displaced small in the width direction of the sheet material. Since the sheet material is reciprocated in the width direction with the period and amplitude, if the thickness of the sheet material is sampled at a predetermined interval by such a thickness gauge, a predetermined value of the sheet material is obtained from the measured data. The average weight per predetermined area in the divided area, that is, the basis weight of the divided area is calculated. Then, using the deviation between the calculated weight and the target weight as a control amount, the basis weight of the formed sheet material is controlled.

(Embodiment) An embodiment of the present invention will be described below with reference to FIG. 1 to FIG.

FIG. 1 shows a production apparatus 10 for implementing a thickness control method of the present invention to produce a resin-carrying release sheet as a sheet material.

The manufacturing apparatus 10 includes an unwinding machine 12, and a roll 16 on which a release sheet 14 is wound is rotatably mounted on the unwinding machine 12. The release sheet 14 continuously unwound from the roll 16 passes between the coating roll 18 and the applicator roll 20, and is wound up by the roll 22.

When the release sheet 14 passes between the coating roll 18 and the applicator roll 20, a molten resin 24 for coating is applied on the release sheet 14, thereby forming a resin-carrying release sheet 25. Will be. Therefore, the resin-carrying release sheet 25 having the resin sheet formed on the release sheet 14 is wound around the roll 22.

To describe the molding of the resin-carrying release sheet 25 in detail, the molten resin 24 is obtained by heating and melting the resin block 26 with the heating roll 30.
From the pot 32 once. Then, the molten resin 24 in the pot 32 passes through the gap 36 between the coating roll 18 and the metering roll 34 from the pot 32, whereby a resin sheet 38 is formed on the outer peripheral surface of the coating roll 18, and By transferring the resin sheet 38 onto the release sheet 14 passing between the coating roll 18 and the applicator roll 20, the resin-carrying release sheet 25 is formed.

Each of the coating roll 18, applicator roll 20, heating roll 30, and metering roll 34 has a heater inside.
The roll 40 can be heated to a predetermined temperature by the heater 40. Instead of using the heater 40, a heat medium may be supplied into each roll to heat the roll to a predetermined temperature.

The coating roll 18 and the applicator roll 20
The metering rolls 34 are independently rotated via appropriate driving means (not shown), and the rotation speed is controlled by the controller 42.

The first and second areal gauges 44 and 46 made up of thickness gauges are provided on the traveling path of the release sheet 14 from the roll 16 to the roll 22.
Is arranged. The first weight meter 44 is positioned between the roll 16 and the applicator roll 20, and the second weight meter 46 is located between the applicator roll 20 and the roll 22 on the side of the applicator roll 20. It is positioned. Therefore, the first weight meter 44 measures the thickness of the release sheet 14,
The second weight meter 46 measures the thickness of the resin-carrying release sheet 25.

The first and second basis weights 44 and 46 are mounted on a common frame 48, and are reciprocated in the width direction of the release sheet 14 or the resin-carrying release sheet 25. First
The reciprocating motion of the second weights 44 and 46 can be realized by, for example, a reciprocating drive mechanism 50 shown in FIG. Although the reciprocating drive mechanism 50 shown in FIG. 2 is directed to the second weight meter 46, the same reciprocating drive mechanism can be used in the case of the first weight meter 44.

The reciprocating drive mechanism 50 includes a slider 52 that is movable with respect to the frame 48. The slider 52 has a pair of arms 54 and 56 horizontally extending in the width direction of the resin-carrying release sheet 25 above and below the resin-carrying release sheet 25,
The slider 52 can reciprocate in the width direction of the resin-carrying release sheet 25 by an actuator (not shown).
A second weight 46 is attached to the distal end of the arms 54 and 56 of the slider 52 so as to be movable in the width direction of the resin-carrying release sheet 25 with respect to the slider 52. In the case of this embodiment, the first and second weight meters 44 and 46 are transmission-type thickness meters that measure the thickness of the object based on the deviation between the incident energy with respect to the object and the transmitted energy from the object. Therefore, when the second weight meter 46 is viewed, the second weight meter 46 is disposed on one arm 54 side and carries a detection line such as a β-ray, an X-ray, or an infrared ray. An emission portion 58 that emits light toward the release sheet 25, and the other arm 56
The receiving portion 60 is disposed so as to face the emission section 58 with the resin-carrying release sheet 25 interposed therebetween, and receives a detection line transmitted through the resin-carrying release sheet 25. Each of the emitting section 58 and the receiving section 60 is supported by a corresponding arm of the slider 52, and is slidably attached to a guide rod 62 extending in the width direction of the resin-carrying release sheet 25, and in the width direction. It is connected to a reciprocable carriage 64. Therefore, as the carriage 64 reciprocates,
Each of the emission unit 58 and the reception unit 60 can reciprocate in the width direction of the resin-carrying release sheet 25. It goes without saying that the emitting unit 58 and the receiving unit 60 are reciprocated synchronously while always maintaining the facing state.

Therefore, according to the reciprocating mechanism 50 described above, the carriage
By driving the second weight 64, the second weight 46, that is, the light emitting portion 58 and the receiving portion 60 are reciprocally displaced with the first amplitude and the first cycle in the width direction of the resin-carrying release sheet 25. At the same time, the entirety of the slider 52 is
Is reciprocated in the width direction with a second amplitude and a second cycle that are larger than the first amplitude and the first cycle, respectively. Exercise will be implemented. In the case of this embodiment, the second amplitude corresponds to the width dimension of the resin-carrying release sheet 25. Although not shown, the first weight meter 44 has the same structure as the second weight meter 46, and can perform the same reciprocating motion.

Next, the thickness control method will be described with reference to the flowchart of FIG.

First, in step S1, the first and second weights 44, 46
Starts the reciprocating motion described above. In this case, the first and second weights 44 and 46 are displaced along the width direction of the release sheet 14 or the resin-carrying release sheet 25 along a locus as shown by a solid line in FIG. become. That is, the first and second
The basis weights 44 and 46 are reciprocated at the second amplitude while scanning a width region corresponding to the first amplitude.

Then, in the next step S2, the thickness of the release sheet 14 is sampled at predetermined time intervals by the first weight meter 44, and then in step S3, the release sheet 14 is released based on the measurement data in step S2. The weight per predetermined area in the mold sheet 14, that is, the basis weight W0 is calculated. Here, the sectional area of the release sheet 14 is defined by the first amplitude in the width direction of the release sheet 14, and the second area in the length direction of the release sheet 14.
A half cycle of the cycle, that is, the first weight 44 is defined by the running length of the release sheet 14 from one side edge to the other side edge of the release sheet 14. In this case, the length direction of the divided area may be defined in the second cycle. Therefore, the measured data obtained by sampling this sectioned area while the first weight meter 44 scans it is converted into the weight per unit area, that is, the basis weight by a calibration curve obtained in advance, and the average value thereof is obtained. , The basis weight W0 per predetermined area in the release sheet 14 can be calculated.

In the next step S4, as in step S2,
After the thickness of the resin-carrying release sheet 25 is sampled by the second basis total 4, in step S5, based on the measurement data in step S4, the per-section area of the resin-carrying release sheet 25 is determined. The weight, that is, the basis weight W1 is calculated. Here, it is a matter of course that the divided area of the release sheet 14 and the divided area of the resin-carrying release sheet 25 correspond to each other.

In the next step S6, a difference W2 between the basis weight W1 and the basis weight W0 is determined, and the difference W2 represents the basis weight per section in the resin sheet 38 described above. .

Then, thereafter, in step S7, the resin sheet 38
Weight W2 and the target weight WT of the resin sheet 38.
Is obtained, and the difference ΔW is a control amount in the feedback control performed in the next step S8. That is, in step S8, based on the magnitude of the deviation ΔW, the discharge amount of the molten resin 24 from the pot 32 and the gap
By controlling the size of 36, the rotation speed of each of the coating roll 18, the applicator roll 20, and the metering roll 34, and the like, controlling the basis weight W2 of the resin sheet 38 to match the target basis weight WT. become. FIG. 4 shows the relationship between the measured data of the weight meter in the length direction of the sheet and the calculated weight W2.

According to the thickness control method described above, the first and second areal meters are provided.
Because the reciprocating motion described above is given to the 44 and 46, the first and second weights 44 and 46 reciprocate while scanning the area of the release sheet 14 or the resin-carrying release sheet 25. , The thickness data can be sampled. Accordingly, in the case where the conventional weight meter makes a simple reciprocating motion as shown by a broken line and a dashed line in FIG.
If there is local unevenness in thickness outside of the movement trajectory of the weight meter, the site of the local unevenness will deviate from the measurement area in the weight meter, however,
Since the weights 44 and 46 in the present invention are reciprocated while scanning a certain width, that is, a width area corresponding to the first amplitude,
Even if the above-mentioned local unevenness exists, measurement data of the site of the local unevenness can be obtained. Therefore, the basis weight W2 of the resin sheet 38 obtained from the above-described measurement data takes into account the measurement data of the local thickness unevenness in the width direction of the sheet, and furthermore, the divided area is the resin sheet.
Since it has a local length also in the length direction of 38, not only the local thickness in the sheet width direction but also the periodic thickness unevenness in the sheet length direction Is also calculated in consideration of the measurement data, the basis weight W2 of the resin sheet 38 determined in the method of the present invention is highly accurate to the actual basis weight per section determined by the weighing method. Will be. In addition, the basis weight W obtained in this manner is
Is, as is clear from the above description, calculated in consideration of measurement data of thickness unevenness which is generated randomly and locally. The periodic unevenness of the thickness in the length direction of the sheet is caused by eccentricity, bending, and the like of the rolls 18, 20, and 34.

Therefore, in the case of the present invention, the basis weight W2 and the target basis weight WT
Of the resin sheet 38 to be molded is feedback-controlled, and the thickness of the resin sheet 38, that is, the basis weight per unit area of the resin sheet 38, is set to the length. Can be made uniform in the vertical direction.

The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in the case of one embodiment, the weight meter is configured to reciprocate the slider 52 continuously in the width direction of the sheet, but the slider 52 is moved at a time interval of one-half of a half cycle in the second cycle. Therefore, it may be intermittently moved by the first amplitude. In this case,
The trajectory of scanning in the weight meter is as shown in FIG. This movement is given to the weight meter and the resin sheet 38
If the basis weight W2 per unit area is calculated, the basis weight W2 can be made to match the actual basis weight WT.

The scanning trajectory of the weight meter shown in FIGS. 5 and 6 is linear in either the first cycle or the second cycle, but may be sinusoidal.

In addition, in one embodiment, the entire width of the sheet is scanned by one weight meter. However, when the sheet width is wide,
Since it takes time to perform measurement scanning over the entire area of the divided area, the responsiveness of the feedback control may be deteriorated.

However, such a problem can be solved by dividing the width direction of the sheet into a plurality of measurement areas and assigning a basis weight to each measurement area. In this case, the reciprocating motion of each weight meter is performed synchronously, and the weight of the entire sheet is obtained by calculating the average value from the weight of the predetermined section determined from the measurement data of each weight meter. It goes without saying that it is calculated.

Furthermore, in the case of one embodiment, a transmission type thickness gauge is used as a basis weight meter. However, the present invention is not limited to this, and the sheet is irradiated with infrared rays, and the infrared rays reflected from the sheet are attenuated. A reflection type infrared thickness gauge that measures the thickness of the sheet based on the amount may be used. In this case, the reflection type infrared thickness gauge is placed at the position of the second
Since only a single unit needs to be arranged, not only the cost of the apparatus for performing the method of the present invention is reduced, but also the configuration of the reciprocating mechanism of the weight meter is simplified, and furthermore, when calculating the basis weight of the resin sheet. The calculation is also simplified.

(Effects of the Invention) As described above, according to the sheet material thickness control method of the present invention, a small reciprocating displacement having a first amplitude and a first cycle in the width direction of the sheet material is provided to the thickness gauge. Since the reciprocating motion is synthesized by combining the large reciprocating displacement having the second amplitude and the second cycle larger than the first amplitude and the first cycle, the thickness of the sheet material is determined by the thickness gauge. If the sampling is performed at intervals of, an average measured weight per predetermined area in a predetermined section of the sheet material can be obtained with high accuracy from the measurement data. Accordingly, if the thickness of the sheet material to be formed is controlled based on the deviation between the measured weight and the target weight, local thickness unevenness in the width direction of the sheet material, Since the thickness of the sheet material can be controlled in consideration of the periodic thickness unevenness, the weight per predetermined area of the sheet material to be formed can be adjusted with high precision over the length direction. Can be controlled.

[Brief description of the drawings]

1 to 5 show an embodiment of the present invention.
FIG. 2 is a side view showing a resin-carrying type sheet manufacturing apparatus for carrying out the method of one embodiment, FIG. 2 is a side view showing a reciprocating mechanism of a weight meter, and FIG. FIG. 4 is a flow chart for explaining, FIG. 4 is a graph showing the relationship between the calculated data and the weight per unit area of the sheet with respect to the length direction of the sheet, FIG. FIG. 6 shows a modified example of the present invention and is a diagram showing another scanning locus of a weight meter. 14 ... Release sheet, 18 ... Coating roll, 20 ...
Applicator roll, 25 ... Resin release sheet, 34 ...
... Measuring roll, 38 ... Resin sheet, 42 ... Control device, 44
... First weight gauge (thickness gauge), 46... Second weight gauge (thickness gauge).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location D04H 1/70 D04H 1/70 Z

Claims (1)

(57) [Claims] A thickness gauge is displaced in a width direction of a sheet material for a strip-shaped sheet material which is continuously formed and travels.
In this sheet thickness control method, the thickness of the sheet material is sampled and measured at predetermined intervals by the thickness gauge, and the weight per predetermined area of the formed sheet material is controlled based on the measured data. A small reciprocating displacement having a first amplitude and a first cycle in the width direction of the sheet material and a large reciprocating displacement having a second amplitude and a second cycle larger than the first amplitude and the second cycle, respectively; While giving a reciprocating motion combined with the displacement, sampling of measurement data is performed by a thickness gauge, an average weight per predetermined area in a predetermined area of the sheet material is calculated from the measurement data, and the calculated weight is calculated. Controlling the thickness of the sheet material to be equal to the target weight.