JP2007030455A - Sheet molding device, and roll interval controlling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet product having a good quality by the use of a method wherein a roll interval control is stably performed, and the variation in a depressing load is suppressed in the roll internal control which keeps a roll interval at a specified value. <P>SOLUTION: A control deviation ΔG of the roll interval is converted into a control target value F* for the depressing load. Then, a cascade control which adjusts the roll interval in such a manner that the depressing load being applied to a first roll 11 may become the control target value F* is performed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet forming apparatus and a roll gap control method, and in particular, a sheet forming apparatus by a touch roll that passes a sheet between two rolls and performs sheet forming in a state where the front and back surfaces of the sheet are in contact with the two rolls. The present invention relates to a roll gap control method for the sheet forming apparatus.

  As a sheet forming apparatus by an extrusion method, there are two rolls arranged in parallel with a gap, and a sheet (molten resin from a T-die) is passed between the two rolls that are rotationally driven. Some perform sheet forming in a state where the front and back surfaces of the sheet are in contact with the roll (for example, Patent Documents 1 and 2).

  In the conventional sheet forming apparatus, a wedge member is inserted between roll support housings (bearing housings) of two rolls, and one roll support housing is pressed against the other roll support housing by a hydraulic cylinder device to support the two rolls. The roll gap is adjusted by the amount of the wedge member inserted between the housings.

  In this sheet forming apparatus, since a wedge member is sandwiched between two roll support housings, it is quantitatively determined how much force (load) is actually applied to the sheet formed between the two rolls. In other words, the roll gap can only be made constant.

  When performing roll gap control that keeps the roll gap at a predetermined value using a servo control system, in order to hold the roll position at the predetermined position under the control, it is necessary to avoid slight fluctuations in the roll gap for control purposes. I can't.

On the other hand, since the molten resin in the bank portion during molding is cooled and the temperature is lowered, the viscosity is high, and the pressing load acting on the roll greatly fluctuates even if the roll gap slightly fluctuates. For this reason, when the fluctuation frequency of the roll gap is high, the fluctuation of the pressing load acting on the roll also increases. This fluctuation of the pressing load causes a defect on the sheet surface or greatly changes the internal residual stress of the formed sheet. Can not get a good quality sheet product.
JP-A-9-155948 Japanese Patent Laid-Open No. 10-34748

  The problem to be solved by the present invention is to perform roll gap control with stability in roll gap control for keeping the roll gap at a predetermined value, and to obtain a high-quality sheet product by suppressing variation in pressing load.

  The sheet forming apparatus according to the present invention has two rolls arranged in parallel with a gap, and a sheet is passed between the two rolls that are rotationally driven, and the front and back surfaces of the sheet are in contact with the two rolls. In a sheet forming apparatus that performs sheet forming in a state in which the two rolls are formed, a roll gap adjusting unit that increases or decreases a roll gap by displacing an arrangement position of at least one of the two rolls, and a gap between the two rolls is a predetermined amount. A roll that sets a control target value of a pressing load acting on the roll so as to become a control target value, and adjusts a roll gap by the roll gap adjusting means so that a pressing load acting on the roll becomes the control target value And a gap control means.

  The sheet forming apparatus according to the present invention has two rolls arranged in parallel with a gap, and a sheet is passed between the two rolls that are rotationally driven, and the front and back surfaces of the sheet are in contact with the two rolls. In a sheet forming apparatus that performs sheet forming in a state of being performed, a roll gap adjusting unit that increases or decreases a roll gap by displacing an arrangement position of at least one of the two rolls, and a gap between the two rolls is measured. Roll gap measuring means, pressing load measuring means for measuring the pressing load acting on the roll, and acting on the roll based on a deviation between the roll gap measured by the roll gap measuring means and a predetermined control target value The control target value of the pressing load is set, and the deviation between the pressing load measured by the pressing load measuring means and the set control target value of the pressing load is And a roll gap control means for adjusting the roll gap by the roll gap adjusting means so as to.

  In the sheet forming apparatus according to the present invention, preferably, the roll gap control means corrects the control target value of the pressing load according to the rotational position of the roll, and performs roll eccentricity compensation.

  A roll gap control method for a sheet forming apparatus according to the present invention includes two rolls arranged in parallel with a gap, and a sheet is passed between the two rolls that are rotationally driven. In a roll gap control method for a sheet forming apparatus that forms a sheet in a state where the front and back surfaces are in contact with each other, a control target value of a pressing load acting on the roll is set so that a gap between the two rolls becomes a predetermined control target value. The roll gap is controlled so that the pressing load acting on the roll becomes the control target value.

  The sheet forming apparatus according to the present invention sets the control target value of the pressing load acting on the roll so that the gap between the two rolls becomes a predetermined control target value, and the control target value in which the pressing load acting on the roll is set Cascade control is performed to adjust the roll gap so that

  The measurement resolution of the roll gap measuring means (displacement meter) for measuring the roll gap is generally about 1 μm, and actually, the roll gap varies by about ± 2 μm at a frequency of several Hz. When the roll gap fluctuates by about ± 2 μm at a frequency of several Hz, the pressing load acting on the roll fluctuates several percent.

  As a result, in the roll gap constant control, the resolution is better when the pressing load is measured and the cascade type feedback control is performed than the roll gap feedback control only by the position measurement, so the stability of the roll gap control is improved. .

  One embodiment of a sheet forming apparatus according to the present invention will be described with reference to FIG.

  The sheet forming apparatus includes a first roll 11 and a second roll 12 on a fixed base 10. The first roll 11 and the second roll 12 are arranged in parallel (parallel).

  The first roll 11 is supported by the left and right shaft end portions 15R and 15L so as to be rotatable by the left and right bearing housings 16R and 16L, and is rotatable about its own central axis. The bearing housings 16R and 16L are engaged with the left and right linear guides 17R and 17L provided on the fixed base 10 so as to be displaceable. Thereby, the first roll 11 can be displaced in the direction A in which the roll gap is increased or decreased with respect to the second roll 12. That is, the arrangement position of the first roll 11 can be displaced (changed) in the direction A in which the roll gap with the second roll 12 is increased or decreased.

  The second roll 12 is supported so that the left and right shaft end portions 23R and 23L can be rotated by left and right bearing housings 24R and 24L fixedly mounted on the fixed base 10, and can rotate about its own central axis. Yes.

  On the fixed base 10, left and right hydraulic cylinder devices 33R and 33L are attached by an attachment member 31 and connecting cylinders 32R and 32L. The piston rods 34R, 34L of the hydraulic cylinder devices 33R, 33L are fixedly connected to the bearing housings 16R, 16L at the tips. The hydraulic cylinder devices 33R and 33L are double-acting types having cylinder chambers 72 and 73 on both sides of the piston 71, respectively.

  As a result, the hydraulic cylinder devices 33R and 33L serve as roll gap adjusting means for increasing and decreasing the roll gap by displacing the arrangement position of the first roll 11, and the left and right bearing housings 16R and 16L are operated by the hydraulic operation of the hydraulic cylinder devices 33R and 33L. Are individually displaced in the roll gap increase / decrease direction A.

  Supply and discharge of hydraulic pressure to and from the cylinder chambers 72 and 73 of the hydraulic cylinder devices 33R and 33L are performed by bidirectional pumps 74R and 74L driven by servo motors 75R and 75L.

  The hydraulic cylinder devices 33R and 33L incorporate displacement meters (position sensors) 41R and 41L. The displacement meters 41R and 41L measure the piston positions of the hydraulic cylinder devices 33R and 33L, and measure the position of the first roll 11, and the roll gap between the first roll 11 and the fixedly arranged second roll 12. Functions as a roll gap measuring means.

  Displacement meters (linear scales) 42R and 42L for detecting the positions of the left and right bearing housings 16R and 16L are attached to the fixed base 10. The displacement meters 42R and 42 also function as roll gap measuring means for measuring the roll gap between the first roll 11 and the fixedly arranged second roll 12 by measuring the positions of the bearing housings 16R and 16L.

  As the roll gap measuring means, any one of displacement gauges 41R and 41L with a built-in hydraulic cylinder or displacement gauges 42R and 42L at the bearing section may be provided. When the displacement gauges 41R and 41L with a built-in hydraulic cylinder are used, the number of parts can be reduced by using an existing displacement cylinder built-in type hydraulic cylinder device. On the other hand, when the displacement gauges 42R and 42L of the bearing portion are used, the roll is not affected by the deformation of the fastening portions of the piston rods 34R and 34L and the piston rods 34R and 34L with the bearing housings 16R and 16L. The gap can be measured with high accuracy. These may be selected according to the required specifications.

  Load cells 43R and 43L are attached to the connecting cylinders 32R and 32L. The load cells 43R and 43L are pressing load measuring means, and measure the load acting on the connecting cylinders 32R and 32L as a load equivalent to the pressing load acting on the first roll 11. Note that the load cells 43R and 43L may be provided at a connecting portion with the bearing housings 16R and 16L at the ends of the piston rods 34R and 34L (see FIG. 4). The pressing load measuring means may be pressure sensors 45R and 45L that measure the hydraulic pressure supplied to the hydraulic cylinder devices 33R and 33L instead of the load cells 43R and 43L.

  Although not shown in the figure, each of the first roll 11 and the second roll 12 is individually connected to an electric motor for driving the rotation of the roll, and the first roll 11 is rotated in the counterclockwise direction in the second direction. Each of the rolls 12 is driven to rotate in the clockwise direction.

  A T die 100 that is long in the roll axis direction is provided above the roll gap between the first roll 11 and the second roll 12. The T-die 100 discharges the molten resin from the lip toward the roll gap between the first roll 11 and the second roll 12. As a result, a melt bank MB made of a molten resin is formed in the upper part of the gap between the first roll 11 and the second roll 12.

  The first roll 11 is driven to rotate in the counterclockwise direction and the second roll 12 is driven to rotate in the clockwise direction, so that both the rolls are disposed at the roll gap portion between the first roll 11 and the second roll 12. With the front and back surfaces of the sheet S in contact with each other, sheet forming is performed in a touch roll manner.

  An electronically controlled roll gap control device 50 using a microcomputer is provided as a roll gap control means. The roll gap control device 50 receives sensor signals (measurement information) from the displacement meters 41R, 41L or 42R, 42L, the load cells 43R, 43L, or the pressure sensors 45R, 45L, and the first roll 11 and the second roll 12 are input. Servo motors 75R and 75L are controlled to control the roll gap.

  The roll gap control device 50 sets a control target value of the pressing load acting on the first roll 11 so that the roll gap between the first roll 11 and the second roll 12 becomes a predetermined control target value. Control is performed to adjust the roll gap so that the pressing load acting on 11 becomes the control target value.

  Details of the roll gap control by the roll gap control device 50 will be described with reference to FIG. The roll gap control device 50 shown in FIG. 2 exists individually for the left and right hydraulic cylinder devices 33R and 33L.

  The roll gap control device 50 is set with a roll gap control target value (gap set value) G *, and the control target value G * is input to the deviation calculator 51.

  The deviation calculating unit 51 inputs the roll gap measurement value G by the displacement gauges 41R, 41L or 42R, 42L from the cylinder / roll system 52 formed by the hydraulic cylinder devices 33R, 33L and the first roll 11, and the control target value G * And a control deviation ΔG between the roll gap measurement value G and the roll gap measurement value G are calculated.

  Since the outputs of the displacement meters 41R, 41L or 42R, 42L may fluctuate at a frequency of about several tens of Hz, the deviation calculation unit 51 includes a roll gap measurement value from which high frequency components have been removed by the high cut filter 53. G is input.

  The roll gap control deviation ΔG is input to the pressing load calculation unit 54. There is a correlation between the roll gap and the pressing load, and the pressing load calculation unit 54 determines the pressing load control target value (load setting) from the roll gap control deviation ΔG according to the correlation between the roll gap and the pressing load identified in advance. Value) F * is calculated.

  The control target value F * increases when the roll gap control deviation ΔG is a negative value, and decreases when the roll gap control deviation ΔG is a positive value. In this embodiment, the control target value F * is calculated as a control target value by PI control.

  The control target value F * of the pressing load is input to the correction calculation unit 55 for feedforward correction. The correction calculation unit 55 inputs the correction value according to the rotation position of the first roll 11 from the correction value setting unit 56 in which the correction value is set according to the load fluctuation pattern due to roll rotation, and corrects the control target value F *. And roll eccentricity compensation. The corrected control target value F * c is input to the deviation calculator 57.

  Here, the roll eccentricity compensation will be described.

  When the distance between the bearings of the two rolls is fixed and molded, the roll gap changes due to slight eccentricity of the rolls. Since the roll gap changes, the pressing load also changes corresponding to the rotation of the roll. At this time, if the distance between the bearings is changed so as to cancel the fluctuation of the pressing load due to the roll eccentricity, the actual roll gap becomes constant, but the actual eccentricity can be accurately determined by the molding temperature. difficult. Further, if the pressing load is made constant, the gap fluctuates more than the amount of eccentricity.

  Therefore, in this embodiment, roll eccentricity compensation is performed in the following manner in order to keep the distance between the bearings constant and reduce the fluctuation of the gap.

  In advance, the sheet is formed in the position control mode of the hydraulic servo, the pressing load at that time is measured, and the variation pattern of the pressing load is stored. If the two roll diameters are different, only the number of rotations corresponding to the distance of the least common multiple of the circumference is stored. For the measurement of the pressing load, the number of rotations is an integral multiple of the stored number of rotations, and the average pattern is obtained. Further, the pressing load at that time (rotational position) is obtained from the rotational position of the roll and the average pattern. The pressing load is set as a target load, and the load is controlled by setting the sum of the deviation from the pressing load and the correction value of the pressing load calculated from the deviation from the target gap as the target load. By doing so, the distance between the bearings can be kept accurately constant even when there is a load fluctuation due to roll eccentricity.

  The deviation calculating unit 57 receives the measured value F of the pressing load acting on the first roll 11 from the load cells 43R and 43L, and calculates the control deviation ΔF between the pressing load control target value F * c and the pressing load measured value F. To do. The control deviation ΔF is input to the motor operation amount calculation unit 58.

  Based on the control deviation ΔF, the motor operation amount calculation unit 58 calculates the rotation speeds of the servo motors 75R and 75L at which the control deviation ΔF becomes zero, and outputs a motor rotation command value to the motor drive unit 59.

  As a result, the servo motors 75R and 75L are driven based on the corrected control target value F * c, and the hydraulic pumps 33R and 33L supply and discharge hydraulic pressure to and from the cylinder chambers 72 and 73 by the bidirectional pumps 74R and 74L. Be controlled.

  Thus, the control target value F * of the pressing load acting on the first roll 11 is set so that the roll gap becomes the predetermined control target value G *, that is, the control deviation ΔG of the roll gap is set to the pressing load. Cascade control is performed in which the roll clearance is adjusted so that the pressing load acting on the first roll 11 becomes the control target value F * after being converted into the control target value F *.

  In the roll gap constant control, it is better to perform the cascade type feedback control by measuring the pressing load than the roll gap feedback control only by position measurement. Stability is improved.

  Thereby, the thickness of the sheet | seat S shape | molded is stabilized, there is no dispersion | variation in sheet | seat thickness, and a good quality sheet product with a favorable sheet surface property can be obtained.

  In the above-described embodiment, hydraulic pressure is supplied to and discharged from the cylinder chambers 72 and 73 of the hydraulic cylinder devices 33R and 33L by the bidirectional pumps 74R and 74L driven by the servo motors 75R and 75L. As shown in FIG. 3, the supply and discharge of hydraulic pressure to and from the cylinder chambers 72 and 73 of 33R and 33L can be performed by electric servo valves 35R and 35L. In this case, the electric servo valves 35R and 35L are connected to oil tanks 36 and oil supply pipes 39R and 39L by a hydraulic pump 38 driven by a servo motor 37, and drain pipes 40R and 40L, which are connected to the left and right hydraulic cylinder devices. An electro-hydraulic servo system that individually controls the supply and discharge of hydraulic pressure to and from 33R and 33L is configured.

  Also in this embodiment, the same cascade control as in the above embodiment is performed, so that the stability of the roll gap control is improved in the roll gap constant control, the sheet thickness is not varied, and the sheet surface property is good. Sheet products can be obtained.

  Further, as shown in FIG. 4, a feed screw type driven by a servo motor can be adopted as the roll gap adjusting means. An embodiment using a feed screw system driven by a servo motor will be described with reference to FIG. 4, parts corresponding to those in FIG. 1 are denoted by the same reference numerals as those in FIG. 1, and description thereof is omitted.

  The front ends of the left and right feed screw members 18R, 18L are fixedly connected to the bearing housings 16R, 16L via load cells 43R, 43L which are pressing load measuring means for measuring the pressing load acting on the first roll 11, respectively. In this embodiment, the pressing load acting on the first roll 11 can also be detected from a current value equivalent to output torque values of servo motors 21R and 21L described later.

  On the fixed base 10, left and right feed nut support bases 19R and 19L are fixedly arranged. The feed nut support bases 19R and 19L rotatably support the left and right feed nut members 20R and 20L. The feed screw members 18R and 18L are individually screw-engaged with the feed nut members 20R and 20L. Left and right servo motors 21R and 21L are mounted on the feed nut support bases 19R and 19L. The servo motors 21R and 21L are drivingly connected to the feed nut members 20R and 20L by the gear trains 22R and 22L, and rotationally drive the feed nut members 20R and 20L.

  When the feed nut member 20R is rotated by the servo motor 21R, the feed screw member 18R moves in the axial direction (roll gap increasing / decreasing direction A), and the right bearing housing 16R corresponds to the rotation angle (rotation amount) of the servo motor 21R. To displace in the roll gap increasing / decreasing direction A. Further, when the feed nut member 20L is rotated by the servo motor 21L, the feed screw member 18L moves in the axial direction (roll gap increasing / decreasing direction A), and the left bearing housing 16L is separated from the right bearing housing 16R. Then, it is displaced in the roll gap increasing / decreasing direction A according to the rotation angle (rotation amount) of the servo motor 21L.

  As a result, individual roll gap adjusting means are formed at the left and right shaft end portions of the first roll 11.

  Also in this embodiment, the same cascade control as in the above embodiment is performed, so that the stability of the roll gap control is improved in the roll gap constant control, the sheet thickness is not varied, and the sheet surface property is good. Sheet products can be obtained.

It is a whole lineblock diagram showing one embodiment of a sheet forming device by this invention. It is a block diagram which shows the detail of the roll clearance control apparatus in the sheet forming apparatus of this embodiment. It is a whole block diagram which shows other embodiment of the sheet forming apparatus by this invention. It is a whole block diagram which shows other embodiment of the sheet forming apparatus by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fixed base 11 1st roll 12 2nd roll 16R, 16L Bearing housing 17R, 17L Linear guide 18R, 18L Feed screw member 19R, 19L Feed nut support base 20R, 20L Feed nut member 21R, 21L Servo motor 22R, 22L Gear Row 23R, 23L Shaft end 24R, 24L Bearing housing 33R, 33L Hydraulic cylinder device 41R, 41L, 42R, 42L Displacement meter 43R, 43L Load cell 45R, 45L Pressure sensor 50 Roll gap control device 51 Deviation calculation unit 52 Cylinder / roll system 53 High cut filter 54 Push load calculation unit 55 Correction calculation unit 56 Correction value setting unit 57 Deviation calculation unit 58 Motor operation amount calculation unit 59 Motor drive unit 74R, 74L Bidirectional pump 75R, 75L Servo motor 100 T

Claims (4)

A sheet having two rolls arranged in parallel with a gap, passing a sheet between the two rolls that are rotationally driven, and performing sheet forming in a state where the front and back surfaces of the sheet are in contact with the two rolls In the molding equipment,
Roll gap adjusting means for increasing or decreasing the roll gap by displacing the arrangement position of at least one of the two rolls;
The control target value of the pressing load acting on the roll is set so that the gap between the two rolls becomes a predetermined control target value, and the roll gap is set so that the pressing load acting on the roll becomes the control target value. Roll gap control means for adjusting the roll gap by the adjustment means;
A sheet forming apparatus having: A sheet having two rolls arranged in parallel with a gap, passing a sheet between the two rolls that are rotationally driven, and performing sheet forming in a state where the front and back surfaces of the sheet are in contact with the two rolls In the molding equipment,
Roll gap adjusting means for increasing or decreasing the roll gap by displacing the arrangement position of at least one of the two rolls;
Roll gap measuring means for measuring the gap between the two rolls;
A pressing load measuring means for measuring a pressing load acting on the roll;
The control target value of the pressing load acting on the roll is set based on the deviation between the roll gap measured by the roll gap measuring means and a predetermined control target value, and the pressing load and setting measured by the pressing load measuring means are set. A roll gap control means for adjusting a roll gap by the roll gap adjustment means so that a deviation from the control target value of the pressing load is zero.   3. The sheet forming apparatus according to claim 1, wherein the roll gap control unit corrects a control target value of the pressing load according to a rotation position of the roll and performs roll eccentricity compensation. A sheet having two rolls arranged in parallel with a gap, passing a sheet between the two rolls that are rotationally driven, and performing sheet forming in a state where the front and back surfaces of the sheet are in contact with the two rolls In the method for controlling the roll gap of the molding apparatus,
The control target value of the pressing load acting on the roll is set so that the gap between the two rolls becomes a predetermined control target value, and the roll gap is set so that the pressing load acting on the roll becomes the control target value. A roll gap control method for a sheet forming apparatus to be controlled.

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