KR100751977B1 - Sheet forming apparatus and method of controlling the same - Google Patents

Abstract

TECHNICAL FIELD The present invention relates to a sheet forming apparatus and a control method thereof which automatically adjust roll gap to facilitate an operation at the time of setting or changing a forming condition. Specifically, one embodiment of the present invention controls the sheet removal speed (roll rotational speed) according to the deviation of the measured value from the set value of the roll gap under constant pressure load control.

Sheet forming apparatus, roll, roll gap adjusting means, roll gap controlling means, sheet removing speed controlling means

Description

Sheet Forming Apparatus and Control Method thereof {SHEET FORMING APPARATUS AND METHOD OF CONTROLLING THE SAME}

1 is a schematic view of a sheet forming apparatus according to a first embodiment of the present invention.

Fig. 2 is a time chart showing the operation sequence of the sheet forming apparatus according to the present embodiment when sheet forming is started.

3 illustrates a method of using a guide sheet when starting sheet formation.

<Explanation of symbols for main parts of the drawings>

10: stable donation

11: first roll

12: second roll

13: third roll

16R, 16L, 24R, 24L, 27R, 27L: Bearing Housing

28R, 28L, 29R, 29L: Mechanical Stopper

33R, 33L: Hydraulic Cylinder Unit

41R, 41L, 42R, 42L: Displacement Meter

50: control unit

51: roll clearance control section

52: sheet removal speed control section

81, 82, 83: electric motor

100: T die

110: extrusion machine

112: Screw Drive Motor

200: guide sheet

201, 202: Sheet

The present invention relates to a sheet forming apparatus and a control method thereof, and in particular, a sheet forming apparatus using a touch roll for forming a sheet by passing between two rolls in such a manner that the sheet is in contact with the roll, respectively. It relates to a method of controlling such a sheet forming apparatus.

A sheet forming apparatus according to an extrusion molding method includes two rolls arranged in parallel with each other with a gap therebetween, and the sheet (molten resin from the T die) is driven to rotate while the front and back surfaces of the sheet are in contact with the rolls, respectively. There is a device passing between two rolls (see Japanese Patent Application Laid-Open Nos. 09-155948 and 10-34748).

In the sheet forming apparatus of the related art, a wedge member is inserted between two roll supporting housings (bearing housings) each supporting two rolls, and one of the roll supporting housings is pressed onto the other housing using a hydraulic cylinder device. The roll gap is controlled by inserting the wedge member to a predetermined depth between the two roll support housings.

In such a sheet forming apparatus, since the wedge member is inserted between two roll supporting housings, it is not only possible to quantitatively measure the force (load) applied on the sheet to be formed, but also to keep the roll gap constant.

If the extrusion amount of molten resin from the T die is increased (or changes the forming conditions) at the start of operation, the roll gap must be widened. However, when the gap is delayed, a larger melt bank is formed on the upper roll. Abnormally large melt banks may overload the roll drive motor or cause surface defects such as bank marks and the like. In addition, the molten resin of the molten bank adheres to the T die lip to contaminate the T die lip.

On the other hand, when the amount of extrusion of the molten resin from the T die is reduced (or changes the forming conditions) at the start of operation, the roll gap must be narrowed. However, when the gap is delayed, the roll cannot be contacted with the sheet to be formed. In this case, the sheet is not sufficiently cooled by the rolls. Therefore, the sheet is no longer fully cured, resulting in a soft sheet in which the sheet may fall off the roll in its lower portion.

Conventionally, the roll gap was manually adjusted by the operator of such a forming apparatus. That is, the operator adjusts the roll gap by observing the size of the melt bank while controlling the extrusion machine and the line speed. As mentioned above, when the roll gap is excessively wide, the sheet cannot be cooled sufficiently and a portion thereof is stretched and wound around the roll. On the other hand, when the roll is excessively narrow, the molten bank which causes surface defects such as bank marks on the sheet becomes large and overloads the roll drive motor to stop. Therefore, the forming apparatus needs to be continuously adjusted by the operator.

In the past, a method known as a so-called simple proportional operation in which the sheet removal rate is simply changed in proportion to the rotational speed of the screw of the extrusion machine was once used. In this method, the extrusion amount of the molten resin from the extrusion machine is delayed and adjusted by the change of the rotational speed of the screw. Therefore, when the rotational speed changes rapidly, the roll gap changes before the extrusion amount changes with the speed change, causing problems such as sheet suspension, motor overload, and the like. This makes it almost impossible to change the screw speed quickly.

It is an object of the present invention to realize automatic adjustment of the roll gap and sheet removal rate, thereby facilitating the operation upon changing and starting the forming conditions.

A first aspect of the invention comprises two rolls arranged parallel to one another with a gap therebetween, wherein the sheet is formed between the two rolls which are rotationally driven while their front and back surfaces abut the rolls respectively. Provide the device. The sheet forming apparatus includes roll gap adjusting means for displacing at least one of the two rolls to increase or decrease the roll gap between the two rolls, and a pressurized load acting on at least one of the two rolls has a predetermined target control value. The roll gap control means configured to perform constant pressure load control in which the roll gap is adjusted by the roll gap adjustment means, and the deviation of the measured value of the roll gap from the set value under the constant pressurized load control by the roll gap control means. And sheet removing speed control means configured to control the sheet removing speed accordingly.

A second aspect of the invention comprises two rolls arranged parallel to one another with a gap therebetween, the sheet forming a sheet passing between two rolls which are rotationally driven while their front and back surfaces abut the roll, respectively. Provide the device. The sheet forming apparatus includes roll gap adjusting means for displacing at least one of the two rolls to increase or decrease the roll gap between the two rolls, roll gap measuring means configured to measure the roll gap, and at least one of the two rolls. The roll gap is adjusted by the roll gap adjusting means so that the deviation of the measured value measured by the pressurized load measuring means configured to measure the pressurized load acting on the pressurized load from the target control value of the pressurized load is zero. The sheet removal rate according to the roll gap control means configured to perform the constant pressurized load control and the measured value measured by the roll gap measurement means from the predetermined value of the roll gap under the constant pressurized load control by the roll gap control means. Sheet removal speed control means configured to control.

In the sheet forming apparatus according to the first and second aspects, the roll gap control means includes a constant pressurized load control mode for performing constant pressurized load control, and a roll gap so that the roll gap between the two rolls becomes a predetermined target control value. Two modes of constant roll gap control mode are provided in which the roll gap is adjusted using the adjusting means, the roll gap is controlled by the constant pressurized load control mode when initiating sheet formation or changing the forming conditions and the control mode is roll It is preferable to switch to the constant roll gap control mode to control the gap.

A third aspect of the invention comprises two rolls arranged parallel to one another with a gap therebetween, the sheet forming a sheet passing between two rolls which are rotationally driven while their front and back surfaces abut the rolls, respectively. Provided is a device control method. The method includes performing constant pressurized load control in which the gap between the two rolls is adjusted such that the pressurized load acting on at least one of the two rolls is at a predetermined target control value, and from the set value under the constant pressurized load control. Controlling the sheet removal rate according to the deviation of the measured value of the roll gap.

A fourth aspect of the present invention includes two rolls arranged parallel to each other with a gap therebetween, wherein the sheet forms a sheet passing between two rolls that are rotationally driven while their front and back surfaces abut the roll, respectively. Provides a method of controlling the device. This method is used when a pressurized load acting on at least one of the two rolls initiates sheet formation or changes the forming conditions to control the sheet removal rate according to the deviation of the measured value of the roll gap from the set value under constant pressurized load control. Performing constant pressurized load control to adjust the roll gap between the two rolls to become a predetermined target control value, and performing constant roll gap control to control the roll gap so that the roll gap becomes the predetermined target control value. It includes.

In the control method of the sheet forming apparatus, the relationship between the extrusion amount of the molten resin from the extrusion machine which is the molten resin feeder and the pressurized load in the constant pressurization load control is determined in advance and the target control value of the pressurization load in the constant pressurization load control. It is preferable to control according to silver extrusion amount.

In the sheet forming apparatus according to the present invention, while a constant pressurized load control is performed to control the roll gap so that the pressurized load acting on at least one of the rolls becomes a target control value, the sheet removal rate is determined by the measured value from the predetermined value of the roll gap. It is controlled according to the deviation. Therefore, the roll gap and the sheet removal rate are automatically adjusted when the extrusion amount is changed, so that even when the sheet forming conditions are changed, an appropriate pressurized load can be applied to form a melt bank of an appropriate size.

Therefore, the long-standing disadvantage of soft and less hardened sheets falling off the rolls and falling or the melt banks becoming very large to cause surface defects on the sheets or overloading the roll drive motor is eliminated, thereby changing sheet forming conditions and Facilitate operations involving settings.

Referring to Fig. 1, there is shown a sheet forming apparatus according to a first embodiment of the present invention.

The sheet forming apparatus has a first roll 11, a second roll 12, and a third roll 13, all of which are present on the stable base 10. The first roll 11, the second roll 12 and the third roll 13 are arranged side by side (parallel) to each other.

The first roll 11 is rotatably supported by the left bearing housing 16L and the right bearing housing 16R at the left end 15L and the right end 15R of the shaft, centering on the central axis line thereof. Can be rotated. The bearing housings 16R, 16L are displaceably coupled with the right linear guide 17R and the left linear guide 17L provided on the stable base 10. This allows the first roll 11 to be displaced along the direction A with respect to the second roll 12 to increase or decrease the roll gap therebetween. That is, the position of the first roll 11 may be shifted (changed) in the direction A that allows the roll gap to be changed relative to the second roll 12.

The second roll 12 is rotatably supported at the left end 23L and the right end 23R of the shaft by a left bearing housing 24L and a right bearing housing 24R fixedly provided on the stable base 10. Can be rotated about its central axis line.

The third roll 13 is rotatably supported at the left end 26L and the right end 26R of the shaft by the left bearing housing 27L and the right bearing housing 27R provided fixedly to the stable base 10. Can be rotated about its central axis line. By the way, the third roll 13 may be displaced (changed) along the direction A such that the gap may change with respect to the second roll 12, as in the case of the roll 11. The position of the third roll 13 can be adjusted by the roll gap adjusting means substantially the same as the roll gap adjusting means used for the first roll 11 (described later).

On the stable base 10, the left hydraulic cylinder device 33L and the right hydraulic cylinder device 33R are mounted by the mounting member 31. The piston rods 34R, 34L of the hydraulic cylinder devices 33R, 33L are fixedly connected to the bearing housings 16R, 16L via load cells 43R, 43L at their respective ends.

The load cells 43R and 43L, which are pressurized load measuring means, are located where the ends of the bearing housings 16R and 16L and the piston rods 34R and 34L are linked. The load cells 43R and 43L measure the pressurized load acting on the first roll 11.

The hydraulic cylinder devices 33R and 33L function as double acting and roll gap adjusting means having cylinder chambers 72 and 73 on both sides of each piston 71. That is, the hydraulic cylinder devices 33R, 33L displace the position of the first roll 11 to increase or decrease the roll gap. The hydraulic cylinder devices 33R, 33L apply hydraulic pressure to the left bearing housing 16L and the right bearing housing 16R, respectively, to move the housings 16R, 16L in the direction A to increase or decrease the roll gap, respectively. Displace.

The pressure oils for the hydraulic cylinder devices 33R and 33L are supplied to or returned from the cylinder chambers 72 and 73 by means of anisotropic pumps 74R and 74L respectively driven by the servomotors 75R and 75L.

The hydraulic cylinder devices 33R and 33L have a built-in displacement meter (position sensor). The displacement meters 41R and 41L serve to locate the piston in the hydraulic cylinder devices 33R and 33L, thereby functioning as positioners of the first roll 11 and being fixedly arranged with the first roll 11. It also functions as a roll gap measurement means for measuring the roll gap between the rolls 12.

On the stable base 10, displacement meters (linear scales) 42R and 42L which detect the positions of the left and right bearing housings 16R and 16L, respectively, are mounted. The displacement meters 42R and 42L function as roll gap measuring means for locating the bearing housings 16R and 16L and measuring the roll gap between the first roll 11 and the second roll 12 fixedly arranged.

By the way, as roll gap measuring means, either the displacement meters 41R and 41L built in the hydraulic cylinder, or the displacement meters 42R and 42L located in the bearing part can be provided. When the displacement meters 41R and 41L are used to constitute the roll gap measuring means, the use of the hydraulic cylinder device with the built-in displacement gauge can reduce the number of components or members. On the other hand, when the displacement meters 42R and 42L are used, the roll gap is measured with higher precision without being affected by the deformation of the connection portion in which the piston rods 34R and 34L are connected to the bearing housings 16R and 16L. Which one is chosen depends on the specification requirements.

Alternatively, both displacement meters 41R, 41L embedded in the hydraulic cylinder and displacement gauges 42R, 42L of the bearing portion can be used. In such a case, the displacement meters 41R and 41L incorporated in the hydraulic cylinder are used in the first position because sensitive and stable control is expected. In addition, displacement meters 42R and 42L, which are located close to the roll and provide direct data, are used to additionally measure the roll gap. Thereafter, the measured values by the displacement meters 41R and 41L are corrected by the values measured by the displacement meters 42R and 42L.

By the way, the pressure conformity measuring means may be composed of pressure sensors 45R and 45L for measuring the hydraulic pressure in the hydraulic cylinder devices 33R and 33L instead of the load cells 43R and 43L.

The first roll 11, the second roll 12, and the third roll 13 rotate the first roll 11 and the third roll 13 counterclockwise and the second roll 12 clockwise. Respectively coupled to the electric motors 81, 82, 83 to rotate the rolls to rotate.

The circumferential speeds of the first roll 11, the second roll 12, and the third roll 13 determine the sheet removal speed. Therefore, the sheet removal speed can be controlled by controlling the rotation speeds of the electric motors 81, 82, 83. In this embodiment, the rotational speed of the second roll 12 (electric motor 82) is set as the reference speed, but the first roll 11 (electric motor 81) and the third roll 13 (electric The rotational speed of the motor 83 is controlled to determine the sheet removal speed or the traction speed.

A long T die 100 is provided over the roll gap between the first roll 11 and the second roll 12. Molten resin is supplied to the T die 100 from an extrusion machine 110 that includes a screw 111 that is rotationally driven by a screw drive motor 112. The extrusion machine 110 functions as a molten resin feeder to the T die 100 and the extrusion amount of the molten resin is quantitatively controlled by controlling the speed of the screw 111 or the screw drive motor 112.

The extrusion amount of the molten resin from the extrusion machine 110 may be adjusted manually or automatically at a predetermined ratio.

By the way, the extrusion amount of molten resin can be adjusted by the rotational speed of a gear pump (not shown) or the raw material feed amount to a raw material feeder.

The T die 100 discharges the molten resin from the lip portion thereof into the roll gap between the first roll 11 and the second roll 12, and rolls between the first roll 11 and the second roll 12. Create a molten bank MB above the gap.

Thereafter, since the first roll 11 and the third roll 13 are driven to rotate in the counterclockwise direction, and the second roll 12 is driven to the clockwise direction, the sheet is formed by the front and rear surfaces of the sheet S being removed. The so-called touch roll method of contacting the rolls when passing through the gap between the first roll 11 and the second roll 12 and then passing through the gap between the second roll 12 and the third roll 13, respectively. Is obtained by.

An electrically controlled control device 50 using a computer is provided. The control device 50 controls the servomotors 75R and 75L to control the roll gap between the first roll 11 and the second roll 12 and the displacement meter 41R, 41L or 42R, 42L and the load cell 43R. , 43L) or a roll clearance control section 51 for inputting sensor signals (measurement data) from the pressure sensors 45R, 45L, respectively, and the sheet removal controlling the electric motors 81, 82, 83 to control the sheet removal speed. Control section 52.

The roll gap control section 51 has a roll gap such that the roll gap between the first roll 11 and the second roll 12 measured by the displacement meter 41R, 41L or 42R, 42L has a predetermined target value. The predetermined roll gap control mode adjusted by the servomotors 75R and 75L, and the pressurized load on the first roll 11 measured by the load cells 43R and 43L or the pressure sensors 45R and 45L are predetermined targets. One of the two control modes of the constant pressurized load control mode in which the roll gap is adjusted by the servomotors 75R and 75L can be selectively performed so as to have a value.

Constant roll clearance control is a measured value measured with respect to the roll clearance between the first roll 11 and the second roll 12 by a displacement meter 41R, 41L or 42R, 42L from a predetermined control target value of the roll clearance. The servomotors 75R and 75L are controlled to have a deviation of zero.

The constant pressurization load control has a deviation of the measured value measured with respect to the pressurization load on the first roll 11 by the load cells 43R, 43L or the pressure sensors 45R, 45L from a predetermined target value of the pressurization rod. The servomotors 75R and 75L are controlled so as to achieve this.

In the present embodiment, the roll gap control section 51 controls the roll gap in accordance with the constant pressurized load control at the first position at the start of or immediately after the sheet formation or the formation condition change. Then, if the extrusion amount from the extrusion machine 110 reaches a predetermined target value and the roll gap measured by the displacement meter 41R, 41L or 42R, 42L is within a predetermined range, for example, the control mode is a constant pressurized load control. Switch to constant roll clearance control at.

The sheet removal control section 52 adjusts the speed of the electric motors 81, 82, 83 according to the deviation of the roll gap measured by the displacement meter 41R, 41L or 42R, 42L from the predetermined value to control the sheet removal speed. To control. The predetermined value of the roll gap may correspond to the control target value of the roll gap to be used for the constant roll gap control followed by the constant pressure load control.

The higher the sheet removal rate, the thinner the sheet thickness. Therefore, the sheet removal speed control section 52 controls the sheet removal speed so as to increase the speed when the roll gap becomes larger than the predetermined value due to the increase and decrease of the extrusion amount and the roll gap becomes narrower than the predetermined value.

Therefore, when the roll gap is wider than the control target value, the sheet becomes thicker than the predetermined value, so that the sheet thickness is controlled to be thinner by increasing the sheet removing speed. On the other hand, when the roll gap is narrower than the control target value, the sheet becomes thinner than the predetermined value, so that the sheet thickness is controlled to be thicker by reducing the sheet speed.

By this control, the sheet removal rate can be increased or decreased in accordance with the amount of extrusion from the extrusion machine 110 to maintain a constant sheet thickness and the size of the melt bank MB.

Referring to the time chart shown in Fig. 2, the method of controlling the sheet forming apparatus described above when sheet forming is started will be described below.

At time T1, sheet formation preparation is started. The guide sheet 200 is inserted in advance to pass through the sheet path line as shown in FIG. The guide sheet 200 is composed of a sheet 201 and a sheet 202 made of a cloth or a heat resistant film, and the tip portion of the sheet 201 is attached to an intermediate portion of the sheet 202 so as to be formed in a Y-shape as a whole. The sheet 201 is wound around the first roll 11, and the tip of the sheet 202 is wrapped around the second roll 12.

After the roll gap is set to the minimum gap G _min narrower than the target control value G ^* in the constant roll gap control, the first roll 11, the second roll 12, and the third roll 13 Initiation of rotation at a predetermined creeping speed. The minimum gap G _min is accurately set by bringing the bearing housings 24R, 24L and the mechanical stoppers 28R, 28L, and 29R, 29L provided in the bearing housings 16R, 16L. After the stopper abuts on the housing, the pressure load is set to the target value F ^* , and then constant pressure load control is started.

At time T2, the extrusion machine 110 starts operation and the roll gap control section 51 actually starts to perform constant pressurized load control to maintain the pressurized load at the target control value F ^* . The extrusion amount of the molten resin by the extrusion machine 110 is increased or decreased at a predetermined ratio manually or automatically. The extrusion amount of the molten resin by the extrusion machine 110 is adjusted by controlling the rotational speed of the screw of the extrusion machine, the rotational speed of the gear pump, the raw material supply amount of the raw material supply device, and the like.

The target control value F ^* in the constant pressurization load control is set to a value smaller than the value determined at sheet formation and is increased when the extrusion amount is increased to some extent. When the amount of extrusion is further increased and the temperature of the molten resin of the molten bank MB becomes higher, the target control value F ^* can be reduced. Alternatively, the target control value F ^* may be changed in accordance with the change of the extrusion amount when the relationship between the extrusion amount and the pressurized load is predetermined.

The molten resin from the extrusion machine 110 is supplied to the T die 100 and then dropped therefrom and supplied to the gap between the first roll 11 and the second roll 12. At this time, the molten resin falls into the valley formed between the sheet 201 and the sheet 202 of the guide sheet 200. That is, the molten resin is accommodated by the guide sheet 200. Therefore, the molten resin is surely prevented from falling down the roll when starting to supply the molten resin into the gap between the first roll 11 and the second roll 12. Thereafter, the guide sheet 200 is removed downstream of the sheet path line by the rotation of the first roll 11, the second roll 12, and the third roll 13.

During the constant pressurized load control by the roll gap control section 51, the electric motors 81, 82, 83 perform a predetermined value of the roll gap, that is, a target control value G ^* used during the constant roll gap control in this embodiment. From the displacement meter 41R, 41L or 42R, 42L from the control, it is controlled to adjust the speed according to the deviation of the measured value measured with respect to the roll clearance. This makes it possible to control the sheet removal speed by controlling the rotational speed V of the first roll 11, the second roll 12, and the third roll 13.

Control of the sheet removal rate of speed is due to the increase in roll gap is an extrusion amount (Q) a predetermined value (a target control value (G ^*)) when that is wider than the increase and the roll gap is a predetermined value (target claim eogap (G ^* Narrower than)).

Therefore, when the amount of extrusion is changed during such sheet formation, the roll gap and the sheet removal rate are automatically adjusted so that an appropriately sized molten bank can be formed under an appropriate press load even when the sheet forming conditions are changed.

The result is the elimination of the long-standing disadvantage of soft and less hardened sheets falling off the rolls and falling or the melt banks becoming very large causing surface defects on the sheets or overloading the roll drive motor. Therefore, the operation including changing and setting of sheet forming conditions can be easily executed.

At time T3, the amount of extrusion from the extrusion machine 110 reaches the target amount. Thereafter, when the roll gap G is within a predetermined range at time T4, the control mode is switched from constant pressurization load control to constant roll gap control. Subsequently, the sheet (product) S is produced under constant roll gap control. By the way, switching from constant pressure load control to constant roll gap control does not necessarily need to be performed according to the above-described method, but can be performed according to various conditions including time control and the like.

However, in the above embodiment, the pressure oil is supplied to the cylinder chambers 72 and 73 of the hydraulic cylinder devices 33R and 33L using the anisotropic pumps 74R and 74L driven by the servomotors 75R and 75L. It is returned from there. However, supply and return of pressure oil may be performed by an electric servo valve. Moreover, the supply screw driven by a servomotor can be used as another roll clearance adjustment means.

Those skilled in the art can easily envision additional effects and variations. Therefore, the invention is not limited to the specific elements and representative embodiments shown and described herein in its broadest aspects. Accordingly, various modifications may be made without departing from the spirit and scope of the general inventive concept as defined by the appended claims and their equivalents.

According to the present invention, the long-standing disadvantage of soft and less hardened sheets falling off the rolls and falling or the melt banks becoming very large, causing surface defects on the sheets or overloading the roll drive motor is eliminated, thereby eliminating sheet forming conditions. It is possible to provide a sheet forming apparatus and a method of controlling the same, which facilitates an operation including changing and setting of the present invention.

Claims (7)

Two rolls arranged parallel to each other with a gap therebetween, the sheet being a sheet forming apparatus passing between two rolls which are rotationally driven while the front and back surfaces thereof respectively abut the rolls, Roll gap adjusting means for displacing at least one of the two rolls to increase or decrease the roll gap between the two rolls; Roll gap control means configured to perform constant pressurized load control in which the roll gap is adjusted by the roll gap adjusting means such that the press load acting on at least one of the two rolls is a predetermined target control value; And sheet removing speed controlling means configured to control the sheet removing speed according to the deviation of the measured value of the roll gap from the set value under constant pressurized load control by the roll gap controlling means. Two rolls arranged parallel to each other with a gap therebetween, the sheet being a sheet forming apparatus passing between two rolls which are rotationally driven while the front and back surfaces thereof respectively abut the rolls, Roll gap adjusting means for displacing at least one of the two rolls to increase or decrease the roll gap between the two rolls; Roll gap measuring means configured to measure roll gap, Pressurized load measuring means configured to measure pressurized loads acting on at least one of the two rolls, Roll gap control means configured to perform constant pressurized load control in which the roll gap is adjusted by the roll gap adjusting means such that the deviation of the measured value measured by the pressurized load measuring means from the target control value of the pressurized load becomes zero; Sheet forming apparatus including sheet removing speed controlling means configured to control the sheet removing speed according to the deviation of the measured value measured by the roll gap measuring means from the predetermined value of the roll gap under constant pressurized load control by the roll gap controlling means. . The roll gap control means according to claim 1, wherein the roll gap control means uses a constant pressurized load control mode for performing constant pressurized load control, and a roll gap using means for adjusting the roll gap so that the roll gap between the two rolls becomes a predetermined target control value. Two modes of constant roll gap control mode to adjust are provided, the roll gap is controlled by the constant pressurized load control mode when initiating sheet formation or changing the forming conditions and the control mode is the constant roll gap control mode to control the roll gap Sheet forming apparatus to be switched to. The roll gap control means according to claim 2, wherein the roll gap control means uses a constant pressurized load control mode for performing constant pressurized load control, and a roll gap using means for adjusting the roll gap so that the roll gap between the two rolls becomes a predetermined target control value. Two modes of constant roll gap control mode to adjust are provided, the roll gap is controlled by the constant pressurized load control mode when initiating sheet formation or changing the forming conditions and the control mode is the constant roll gap control mode to control the roll gap Sheet forming apparatus to be switched to. It is provided with two rolls arranged parallel to each other with a gap therebetween, and the sheet is a method for controlling the sheet forming apparatus passing between the two rolls that are rotationally driven while the front and rear surfaces thereof respectively abut the rolls, Performing constant pressurized load control in which the gap between the two rolls is adjusted such that the pressurized load acting on at least one of the two rolls is a predetermined target control value; And controlling the sheet removal speed according to the deviation of the measured value of the roll gap from the set value under the constant pressurized load control. It is provided with two rolls arranged parallel to each other with a gap therebetween, and the sheet is a method for controlling the sheet forming apparatus passing between the two rolls that are rotationally driven while the front and rear surfaces thereof respectively abut the rolls, A predetermined target when a pressurized load acting on at least one of the two rolls initiates sheet formation or changes the forming conditions to control the sheet removal rate according to the deviation of the measured value of the roll gap from the set value under constant pressurized load control. Performing constant pressurized load control to adjust the roll gap between the two rolls to become a control value, And performing constant roll gap control in which the roll gap is controlled so that the roll gap becomes a predetermined target control value. The method according to claim 6, wherein the relationship between the extrusion amount of the molten resin from the extrusion machine which is the molten resin feeder and the pressurized load in the constant pressurization load control is predetermined and the target control value of the pressurization load in the constant pressurization load control is the extrusion amount. The sheet forming apparatus control method controlled according to.

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