JPH1110705A - Apparatus and method for regulating slit gap of mouthpiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately regulate a slit gap of a mouthpiece even when a twist occur due to application of rotary torque to a driving shaft for coupling the head to a motor by outputting a correction of an operating amount of the motor corresponding to a measured twist amount of the shaft. SOLUTION: A motor controller 31 calculates a torque applied to a driving shaft 21 by a load of a motor. A thickness is accurately regulated without influence of a twist of the shaft 21 without using a unit for measuring the twist of the shaft 21 by calculating the twist amount of the shaft 21 by the calculated torque applied to the shaft 21, and giving an operating amount corresponding to the twist amount of the shaft 21 to the motor 23 and hence outputting a correction of the operating amount corresponding to the twist amount. And, a current value of the motor is measured by a measuring instrument 32, and a load of the motor 23 can be measured without using a complicated unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for adjusting a slit gap of a die for controlling a film thickness in a resin film production line.

[0002]

2. Description of the Related Art Generally, improvement in film thickness accuracy not only improves film quality but also improves winding appearance of a take-up roll, and as a result, production yield can be improved. In order to improve the thickness accuracy of the film, it is very important to adjust the thickness unevenness with a die for discharging the molten resin in a sheet shape.

As a method of adjusting the thickness unevenness of the die for adjusting the unevenness of the thickness of the film, a method of mechanically adjusting the slit gap by rotating the bolt for adjusting the slit gap of the die forward and backward by using a motor or the like. is there. In this method, the operation amount can be large, but usually, the motor for rotating the slit gap adjusting bolt is traversed in the width direction of the base and the bolts to be adjusted are sequentially operated, so that it takes a long time to adjust the thickness and can be reached. Thickness accuracy is often inferior to the method of controlling the thermal expansion amount of the adjusting means that can be simultaneously operated over the entire width of the base.

In addition, when the distance between the motor and the slit gap adjusting bolt is long due to the restriction of the peripheral portion of the base, if a torque is applied to the drive shaft in order to rotate the slit gap adjusting bolt forward or backward, the drive is performed. The amount of twist generated in the shaft and transmitted to the slit gap adjusting bolt is an adjustment amount smaller than the adjustment amount originally specified by the control device, and deteriorates the accuracy of thickness adjustment. In particular, since the slit gap adjusting bolt corresponding to the film edge portion requires a large amount of movement for the film product portion,
The torque required to rotate the slit gap adjusting bolt is larger than that of the product part, and the amount of twist generated in the drive shaft is also large. For this reason, the accuracy of adjusting the film thickness is further deteriorated.

In order to eliminate the torsion generated in the drive shaft, it is necessary to adopt a drive shaft having a sufficient rigidity with respect to the torque required for rotating the slit gap adjusting bolt forward or reverse. Good, but if the drive shaft is provided with rigidity until the twist can be completely neglected, the drive shaft becomes thick and large, resulting in poor handling. For this reason, in actual use, the diameter of the drive shaft is often set to a size that is affected by torsion from the viewpoint of handling and restrictions on the device configuration.

Further, in the method using a bolt for adjusting the slit gap, in addition to the above-mentioned problem, an error of the adjustment amount due to the backlash of the screw is included due to the mechanism.
The accuracy of adjusting the film thickness is further deteriorated.

[0007]

As described above, in the conventional slit gap adjusting device for a die, the desired adjustment amount cannot be obtained because the drive shaft is twisted by the torque applied to the drive shaft. Accuracy deteriorates. In addition, if the diameter of the drive shaft is increased to eliminate the twist of the drive shaft, handling becomes poor due to the size of the drive shaft, and handling is deteriorated. Further, depending on the device configuration around the base, it is often not possible to make the drive shaft thick and rigid enough to ignore the twist of the drive shaft. For this reason, the conventional slit gap adjusting device does not always achieve the predetermined purpose.

An object of the present invention is to provide an apparatus and a method for adjusting a slit gap of a die which are excellent in adjusting the thickness of a film. More specifically, a torque for rotating the slit gap adjusting bolt is applied to the drive shaft connecting the base and the motor, and the slit of the base can adjust the slit gap with high accuracy even if the drive shaft is twisted. It is to provide a gap adjusting device and an adjusting method.

[0009]

Means for Solving the Problems To solve the above problems, a slit gap adjusting device for a die according to the present invention discharges a molten resin into a sheet from a slit of the die and forms the sheet into a film. A plurality of slit gap adjusting bolts arranged along the slit extending direction on one of a pair of lips forming a slit gap of the die, and rotating the adjusting bolt forward or reverse in the film manufacturing apparatus. Motor, a drive shaft connecting the adjusting bolt and the motor, a thickness measuring means for measuring the thickness of the film during the film manufacturing process, and a measurement value obtained by the thickness measuring means. And calculating a difference between a predetermined reference value and selecting an adjustment bolt to be operated from among the plurality of adjustment bolts so that the measured value approaches the reference value, A slit gap adjustment for a die, comprising: arithmetic means for calculating the operating direction and the optimal operating amount of the motor corresponding to the operating direction and the optimal operating amount of the motor; and a motor control device for controlling the motor based on the arithmetic result of the arithmetic means. The apparatus further comprises means for measuring the amount of torsion of the drive shaft, and the motor control device corrects and outputs the amount of operation of the motor corresponding to the amount of torsion measured by the measuring means. Consists of

The method for adjusting a slit gap of a die according to the present invention is a method for adjusting a slit gap of a die when discharging molten resin in a sheet form from a slit of the die and forming the sheet into a film. A plurality of slit gap adjusting bolts arranged along the slit extending direction and one of the pair of lips forming the slit gap of the base are provided for rotating the adjusting bolt forward or backward. A motor, a drive shaft connecting the adjusting bolt and the motor, a thickness measuring unit for measuring a thickness of the film during a film manufacturing process, and a measurement value obtained by the thickness measuring unit being predetermined. Calculating a difference from the reference value, and selecting an adjustment bolt to be operated from among the plurality of adjustment bolts so that the measured value approaches the reference value,
A film formed by using a calculation means for calculating the operation direction and the optimum movement amount of the motor corresponding to the operation direction and the optimum movement amount, and a motor control device for controlling the motor based on the calculation result of the calculation means. A method of adjusting a slit gap of a base to adjust a thickness of the motor to a target value, wherein a torsion amount of the drive shaft is obtained, and an operation amount of the motor corresponding to the torsion amount is corrected and output. Become.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with preferred embodiments thereof. In the slit gap adjusting device of the present invention, it is necessary to provide a means for measuring the torsion of the drive shaft, and to correct and output the operation amount corresponding to the torsion amount. That is, since a twist is generated in the drive shaft connecting the slit gap adjusting bolt and the motor, an adjustment amount corresponding to the torsion amount becomes an error with respect to a target adjustment amount specified by the arithmetic means. is there. Also, in order to prevent this, if the diameter of the drive shaft is set to be rigid enough that the twist can be completely ignored, the drive shaft becomes thick and large, so that it is not possible to use a drive shaft suitable for restrictions on handling and equipment configuration. ,further,
The greater the adjustment amount of the slit gap, the greater the load applied to the slit gap adjustment bolt, and the greater the torque required for rotation.Therefore, the amount of twist generated on the drive shaft increases, and a large adjustment amount is output. Therefore, the more the target operation amount indicated by the calculation means, the larger the error will be. Therefore, it is necessary to correct the error caused by the amount of twist.

As the means for measuring the amount of torsion, for example, means for providing an encoder at the tip of the drive shaft and comparing it with the control value of the motor, means for measuring the amount of torsion of the drive shaft by means of a strain gauge, etc. In order to measure the amount of torsion of the drive shaft without using a device, a measuring device for measuring the load on the motor is provided, and the load on the motor is calculated by measuring the current value flowing through the motor using the measuring device. The torque applied to the drive shaft from the calculated motor load is calculated by the calculating means, the amount of torsion generated in the drive shaft is calculated from the calculated torque applied to the drive shaft, and the operation amount corresponding to the calculated amount of torsion of the drive shaft is calculated. A method of performing correction output is preferable.

In the apparatus for adjusting a slit gap of a base according to the present invention, when the load of the motor is below a predetermined lower limit, the operation amount of the motor is calculated while the load is below the lower limit. The amount of operation of the motor after the load exceeds the lower limit is not included in the adjustment amount for the target value instructed from the above, and the amount of operation of the motor is adjusted to the target value instructed by the calculation unit. It is preferable that the slit gap adjusting device controls the motor. That is, when all the correction operation amounts of the motor are included in the adjustment amount with respect to the target value instructed by the arithmetic means, the dead zone of the adjustment bolt caused by the structure of the slit gap adjustment bolt,
This is because the amount of motor operation due to backlash is included, so that the actual adjustment amount becomes smaller than the target value specified by the calculation means, and an error occurs. This problem becomes a serious problem particularly when a slit gap adjusting bolt which has been used for a long time and has a large backlash is used.

Further, according to the present invention, in the die width direction (that is,
Of the plurality of slit gap adjusting bolts arranged in the direction in which the die extends, the slit gap adjusting bolt corresponding to the film edge portion is preferably adjusted to the slit gap by using the motor and the drive shaft.
That is, in the slit gap adjusting bolt corresponding to the film edge portion where a larger operation amount is required for the film product portion, the torque required to rotate the slit gap adjusting bolt is larger than the product portion. This is because the amount of torsion generated in the drive shaft also increases, and the actual adjustment amount decreases with respect to the target value specified by the calculation means, causing an error.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, more specific embodiments will be described with reference to the drawings. FIG. 1 is a sectional view of a die to which the slit gap adjusting device of the present invention is applied. In FIG.
A molten resin (for example, a thermoplastic resin) supplied from an extruder (not shown) flows into a manifold 10 formed in the base 1, and is widened in the base width direction by the manifold 10. The sheet is discharged from the slit 11 in the form of a sheet. Numerous slit gap adjusting bolts 12 are provided on one lip 14b in the vicinity of the slit 11 in the width direction of the base (along the direction in which the slit 11 extends). Based on this, the slit gap is increased or decreased by rotating the slit gap adjusting bolt 12 corresponding to the uneven thickness position forward or backward to adjust the uneven thickness of the film to be formed.

FIG. 2 shows an apparatus for adjusting a slit gap of a base according to an embodiment of the present invention. The slit gap adjusting bolt 12 is connected to a chuck section 20, and the chuck section 20 is connected to a motor 23 via a drive shaft 21 and a speed reducer 22. Motor 23, reduction gear 22,
The drive shaft 21 is provided with the slit gap adjusting bolts 12 and 1.
In this case, the slit gap can be adjusted simultaneously in the die width direction. Further, the drive shaft 21 maintains the strength necessary for rotating the slit gap adjusting bolt 12 forward and backward, and connects the drive shaft 21 and the motor 23 with the slit gap adjusting bolts 12 and 1.
It can be densely arranged in a one-to-one relationship, making it possible to finely adjust the slit gap in the die width direction. The motor 23 can rotate forward or reverse and has a position detector 24 (rotation amount detector).

The operation of the motor 23 is performed according to a command from the motor control device 31. The calculation of the command value is performed based on the thickness unevenness in the film width direction measured by the motor control thickness gauge 33 disposed during the film manufacturing process. The calculation is performed by the calculation unit 30 (calculation means) that has fetched the data via the interface 41. The motor 23 whose operation direction is determined to rotate forward or reverse according to a command value from the motor control device 31
Is fed back from the position detector 24 to the calculation unit 30 via the motor control device 31. Note that the arithmetic unit 30 is connected to the internal storage device 37, and necessary data is stored as appropriate.

When the slit gap adjustment is performed by the apparatus having the above-described configuration, the operation amount of the motor 23 that rotates forward or reverse in accordance with a command value from the motor control device 31 is entirely the same as the operation amount of the slit gap adjustment bolt 12. This does not mean that the drive shaft 21 is partially twisted. Therefore, the operation amount of the slit gap adjusting bolt 12 has an error corresponding to the amount of torsion with respect to the command value from the motor control device 31, and the control accuracy is deteriorated. In response to this error, the load on the motor 23 is measured by measuring the load on the motor 23 with the measuring device 32, and the measured load is fed back to the motor control device 31. The torque applied to 21 is calculated. The torsion amount of the drive shaft 21 is calculated from the calculated torque applied to the drive shaft 21, and an operation amount corresponding to the torsion amount of the drive shaft 21 is given to the motor 23, that is, the operation amount corresponding to the torsion amount is corrected and output. Thus, the thickness can be adjusted with high accuracy without using the device for measuring the torsion of the drive shaft 21 and without being affected by the torsion of the drive shaft 21. Further, by measuring the current value of the motor with the measuring device 32, the load of the motor 23 can be measured without using a complicated device.

FIG. 3 shows an example of control characteristics in another embodiment of the present invention. Slit gap adjusting bolt 12 and reduction gear 2
2 has a backlash due to its structure, and this causes a dead zone where the operation of the motor 23 does not appear as a displacement of the lip 14b and the slit gap 11 does not change. This corresponds to the flat portion of the graph shown in FIG. For this reason, even if the torsion amount of the drive shaft 21 is corrected as described above, if the motor enters the dead zone during the operation process of the motor 23, the control accuracy deteriorates unless the correction output of the operation amount caused by the dead zone is performed. Becomes In order to solve this problem, in the present embodiment, when the current value of the motor 23 is equal to or less than the lower limit, the slit gap adjusting bolt 12 and / or the speed reducer 22 are assumed to enter the dead zone, and the motor 23 Is not included as a control amount.
After the current value of 3 exceeds the lower limit, the motor 23 is controlled according to a predetermined command value. Thus, the slit gap 11 can be accurately adjusted even in a structure having a dead zone due to backlash.

[0020]

According to the first aspect of the present invention, even if a twist occurs in the drive shaft connecting the slit gap adjusting bolt and the motor, the adjustment amount corresponding to the twist amount is corrected and output. Adjust the slit gap of the die to achieve the target film thickness while using a diameter that is not too thick and rigid so that the twist can be completely ignored. be able to. In addition, the larger the adjustment amount of the slit gap, the greater the load applied to the slit gap adjustment bolt, and the larger the torque required for rotation, the larger the amount of torsion generated in the drive shaft. By using the present invention, the amount of torsion generated in the drive shaft is corrected, so that there is a unique effect that the slit gap can be adjusted with high accuracy even when a large adjustment amount is output.

According to the second aspect of the present invention, since the current value of the motor is measured to determine the amount of twist of the drive shaft, the amount of twist of the drive shaft can be reliably measured without using a complicated device. It has the unique effect of being able to.

According to the third aspect of the present invention, the dead zone of the adjusting bolt caused by the structure of the slit gap adjusting bolt,
Since the amount of motor operation due to backlash is not included in the adjustment amount for the specified target value, the slit gap can be adjusted with high accuracy even if the slit gap adjustment bolt that has been used for a long time and has a large backlash is used. In addition, since the output of the torsion amount of the drive shaft is corrected and output, it is possible to achieve a unique effect that the thickness can be adjusted with high accuracy.

According to the fourth aspect of the present invention, since a large amount of operation is required for the film product portion, the torque required to rotate the slit gap adjusting bolt is larger than that of the product portion, and the driving force is increased. Even with the slit gap adjusting bolt corresponding to the film edge portion where the twist generated on the shaft also increases, the adjustment amount corresponding to the twist amount generated on the drive shaft is corrected and output. It is possible to control the amount of operation, adjust the slit gap with high precision, and obtain a unique effect that a film having excellent thickness accuracy can be obtained over the entire width of the die.

According to the fifth aspect of the present invention, even if a twist occurs in the drive shaft connecting the slit gap adjusting bolt and the motor, the adjustment amount corresponding to the twist amount is corrected and output, so that the diameter of the drive shaft can be reduced. It is possible to adjust the slit gap of the die to achieve the target film thickness while using a material that is sufficiently thick and rigid so that the twist can be completely ignored, and that is suitable for handling and restrictions on equipment configuration. it can. In addition, the larger the adjustment amount of the slit gap, the greater the load applied to the slit gap adjustment bolt, and the larger the torque required for rotation, the larger the amount of torsion generated in the drive shaft. By using the present invention, the amount of torsion generated in the drive shaft is corrected, so that there is a unique effect that the slit gap can be adjusted with high accuracy even when a large adjustment amount is output.

According to the sixth aspect of the present invention, since the current value of the motor is measured to determine the amount of twist of the drive shaft, the amount of twist of the drive shaft can be reliably measured without using a complicated device. It has the unique effect of being able to.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view of a resin film base.

FIG. 2 is a schematic configuration diagram of a die slit gap adjusting device according to an embodiment of the present invention.

FIG. 3 is a graph showing a relationship between a current value of a motor and a variation of a slit gap and a rotation angle of the motor according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base 10 Manifold 11 Slit 12 Slit gap adjusting bolt 14a, 14b Lip 20 Chuck unit 21 Drive shaft 22 Reduction gear 23 Motor 24 Position detector 31 Motor control device 32 Motor load measuring device

Claims (6)

[Claims] 1. A film manufacturing apparatus for discharging a molten resin into a sheet from a slit of a die and forming the sheet into a film, wherein one of a pair of lips forming a slit gap of the die is provided with a slit extending. A plurality of slit gap adjusting bolts arranged along the existing direction, a motor provided to rotate the adjusting bolt forward or reverse, a drive shaft connecting the adjusting bolt and the motor, and a film. Thickness measuring means for measuring the thickness of the film during the manufacturing process, calculating a difference between the measured value obtained by the thickness measuring means and a predetermined reference value, so that the measured value approaches the reference value Selecting an adjustment bolt to be operated from among the plurality of adjustment bolts, and determining an operation direction and an optimum operation amount of the motor corresponding to the operation direction and the optimum operation amount. And a motor control device that controls the motor based on the calculation result of the calculation device. A die slit gap adjustment device, comprising: a device that measures a torsion amount of the drive shaft; The apparatus according to claim 1, wherein the apparatus corrects and outputs an operation amount of the motor corresponding to the amount of torsion measured by the measurement unit. 2. A motor measuring device for measuring a load of the motor as a means for measuring the amount of torsion, wherein the motor control device calculates and calculates a motor load from a motor current value measured by the measuring device. 2. The motor according to claim 1, wherein a torque applied to the drive shaft is calculated from a load of the motor, a torsion amount generated in the drive shaft is calculated from the calculated torque, and an operation amount of the motor corresponding to the calculated torsion amount is corrected and output.
Slit gap adjusting device for base. 3. When the load of the motor is equal to or less than a predetermined lower limit, the amount of operation of the motor to be corrected and output is not included in the amount of adjustment to the operation target value instructed by the arithmetic means. 3. The slit gap adjusting device for a die according to claim 2, wherein when the value exceeds a lower limit value, the operation amount of the motor to be corrected and output is an adjustment amount with respect to an operation target value instructed by the arithmetic unit. 4. The slit gap of a die according to claim 1, wherein a slit gap of the adjusting bolt corresponding to a film edge portion of the adjusting bolt is adjusted using the motor and the drive shaft. Adjustment device. 5. A method for adjusting a slit gap of a die when discharging a molten resin into a sheet from a slit of the die and forming the sheet-like material into a film, comprising: a pair of slits forming a slit gap of the die. On one of the lips, a plurality of slit gap adjusting bolts arranged along the slit extending direction, a motor provided to rotate the adjusting bolt forward or reverse, and the adjusting bolt and the motor A drive shaft to be connected, a thickness measuring means for measuring the thickness of the film during the film manufacturing process, and a difference between a measured value obtained by the thickness measuring means and a predetermined reference value is calculated. Of the plurality of adjusting bolts to be operated, so that the operating direction of the motor and the operating direction of the motor corresponding to the optimal operating amount are selected so that the operating value approaches the reference value. Using a calculating means for calculating the amount of operation, and a motor control device for controlling the motor based on the calculation result of the calculating means, adjusting the slit gap of the die to adjust the thickness of the film to be formed to a target value. A method for adjusting a slit gap of a base, comprising: obtaining a twist amount of the drive shaft; and correcting and outputting an operation amount of the motor corresponding to the twist amount. 6. A motor load is calculated by measuring a current value flowing through the motor, a torque applied to the drive shaft is calculated from the calculated motor load, and a torsion generated in the drive shaft is calculated from the calculated torque. 7. The method for adjusting a slit gap of a base according to claim 6, wherein the calculated amount of operation of the motor corresponding to the calculated amount of twist is corrected and output.