GB2146805A

GB2146805A - Automatic control in a web system

Info

Publication number: GB2146805A
Application number: GB08411387A
Authority: GB
Inventors: Edwin James Montalvo
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-09-15
Filing date: 1984-05-03
Publication date: 1985-04-24
Also published as: DE3417347A1; FR2552059A1; JPS6061453A; GB2146805B; IT1199156B; NL8401246A; FR2552059B1; IT8448537A0; GB8411387D0; AU3283284A

Abstract

A system for controlling the rotary motion of a web-handling apparatus used in the processing of webs of sheet material (3) wound on rolls (1) in order to maintain a preset surface speed and tension comprises a drive means for the roll (2) provided with a first tension control means (5) such as a pneumatic or hydraulic brake for adjusting the rotary motion of the drive means and the roll (1). A secondary tension regulating means (6) is also provided and the system acts through an electro-mechanical feedback circuit to regulate web tension as the speed of the rotating roll (1) varies. Pressure in the tension control means (5, 6) is sensed and variations in the sensed pressures corresponding to change in surface speed and web tension exceeding or falling below preset thresholds are processed by an electronic control means (18) to adjust a pressure regulator unit (22) by means of which the tension control means (5, 6) are regulated to restore and maintain the predetermined surface speed and web tension. <IMAGE>

Description

SPECIFICATION A range expander The invention relates to a system for controlling the speed and tension of web materials, in particular to the controlling of the rotary motion of web-handling apparatus of the type used in unwinding rolls or webs of sheet material, in which a pressure sensing electrical transducer is coupled to an electromechanical feed-back control circuit and to a mechanism for adjusting the rotary motion of the apparatus, for providing a substantially constant surface speed and web tension for the roll of sheet material as the roll diameter alters.

Various operations in the manufacture and processing of paper, film, foil and other flexible sheet materials in web form involve the winding, unwinding and rewinding of rolls of the web material. The maintenance of constant operating conditions requires that the surface speed and tension of the web be kept constant during unwinding and rewinding. To maintain constant surface speed and web tension during unwinding as the diameter of a roll decreases, the drive speed of the core on which the material is being wound must be steadily increased, while at the same time, the mass of the roll decreases. Accordingly the drive to the core of a winder or unwinder requires some means for regulating torque output and speed to maintain the tension in the material at a constant level while also keeping the surface speed constant.

Devices and/or systems for controlling the speed and the tension of web materials during a winding process are diclosed for example in U.S. Patent No. 4,049,095. Brake and clutch arrangements for changing the angular speed of a rotatable shaft are disclosed in U.S.

Patent No. 4,366,884.

A range expander is a device which will act as an interface between a brake or clutch, for example as produced by the Montalvo Corporation of Portland, Maine, United States of America, and a web tension control system, which may be pneumatic or electronic. Such brakes or clutches are usually fluid-operated, principally pneumatically.

The purpose of the range expander is to automatically and gradually turn off cylinders, or ranges, in a brake while the roll of web material is being processed. In the case of a clutch for center winding, the range expander will turn on cylinders, or ranges. It will allow converting processors to function within an extremely wide range of operating conditions during unwind braking or rewind clutching.

Thus extremely light weight materials, as well as a large roll of web material on a small core, can now be processed more easily.

In extremely wide range applications, the question of low air pressure in the cylinder at the low end of the range becomes a problem.

The range expander will solve this problem.

When the range expander of the present invention is employed in a conventional unwind, tension control system, there is, essentially one brake pad used for the precise control web tension and one or more other brake pads used to provide a basic tension force, which maintains the tension controlling pad within its optimum control range.

According to the invention there is provided a system for controlling the rotary motor of a web-handling apparatus for rolls of webs of sheet material, comprising: means for providing rotary motion for said apparatus; a fluid activated means for adjusting said rotary motion means; means for sensing the tension of said web within said rotary motion means and for generating an input electric signal in response to said tension: an electronic control means for receiving said input electric signal from said sensing means, and for generating an output electric signal in response to said input electric signal: and means responsive to said output signal for actuating said fluid activated means to adjust said rotary motion means to provide a substantially constant surface speed and web tension for said sheet material.

In another embodiment of the invention a system for controlling the rotary motion of a web-handling apparatus comprises means for: providing rotary motion for said apparatus.

said rotary motion means including a primary or base line rotary motion means and a secondary rotary motion means; a first fluid activated means for adjusting said primary or base line rotary motion means; a second fluid activated means for adjusting said secondary rotary motion means; a first means for sensing the tension of said web within said primary or base line rotary motion means and for generating a first input electric signal in response to said tension; a second means for sensing tension of said web within said secondary rotary means and for generating a second input electric signal in response to said tension;; an electronic control means for receiving said first and said second input electric signals from both of said sensing means, and for generating a first output electric signal in response to said first input electric signal and for generating a second output electric signal in response to said second input electric signal; and means responsive to said output signals for actuating said fluid activated means to adjust said rotary motion means to provide a substantially constant surface speed and web tension for said sheet material.

The electronic controller uses a motor driven pressure regulator to set the air pressure in the friction pad cylinders which control the base line tension.

In a further embodiment of the invention, a pressure transducer, such as the differential pressure gauge marketed by Dwyer Instruments Inc. of Michigan City, Indiana, under the trade mark "Photohelic" can be used to both sense and display the air pressure in the cylinder of a tension controlling friction pad.

Such a transducer device has two adjustable pre-set points. These pre-set points can be used to define the desired operating range for the tension controlling pad. When the tension controlling pressure exceeds the upper limit, a signal will be sent to the control means of the invention, indicating that the control pressure has gone out of range, on the high side. The fact that this condition has occurred will be observable from an examination of the device, in which actual indicator or pointer, indicating the actual pressure, will either be co-incident with, or to the right of, the pre-set limit indicator or pointer which indicates the upper boundary limit of the pressure.

When the control means receives the corresponding information, it will proceed to reduce slowly the air pressure in the cylinders which provide the primary or base line tension. This control action will automatically be inhibited if the web line is not in motion.

The web drive system can according to another aspect of the invention, provide an isolated, normally open contact which closes whenever the line is in motion. If the line is stationary, there is no interaction between the base line pressure pads and the pressure in the tension controlling cylinder. Consequently, if the line has been stopped, without making provision for maintaining the current air pressure in the base line cylinders, there is a possibility that the control means would continue to attempt to change the base line pressure in a vain effort to maintain the tension controlling cylinder within its proper operating range. The result would be to run the base line pressure to its limit, and this would cause a large tension error when the line was re-started.This error would then persist with possibly undesirable results until the control means was given sufficient time to restore the base line pressure to its proper value.

The action is precisely similar when the pressure in the tension regulating cylinder falls below the lower set point setting, as indicated by the movement of the actual pressure indicator or pointer to the left of the lower preset limit or indicator or pointer. In this case the control action is to increase the base line pressure setting to bring the control pressure of the cylinder to within the desired working range.

Whenever the line pressure is changed, the tension control system will respond with a corresponding change to maintain the web tension at its controlled set value. If large, rapid, changes occur in the base line pressure, these changes will have to be matched by correspondingly rapid and large changes in the control pressure, if the web tension is to be maintained at a constant value. Such changes might impose a limitation on the ability of the tension regulator to precisely regulate tension. To avoid unduly interfering with the tension control, the electronic regulator is designed with a built-in restraint means on the maximum speed at which the pressure can be changed. The value of this maximum rate is adjustable from a dial mounted on the control means.This adjustment in range is achieved by moving the regulator motor a small increment at a time, and adjusting the time increment between intervals In addition to this. it may be desirable to use an orifice valve and a small reservoir in the air line supplying the base line pressure.

Such an arrangement would limit the rate of pressure change independently from the control means.

The fact that the base line pressure will be restrained from rapid movement means that the tension regulating system can no longer be used to rapidly bring the tension under control when the web line is set In motion.

There are two basic embodiments which can be constructed in accordance with the invention, for solving this problem.

Generally speaking, the first of these embodiments uses a second pressure transducer to automatically pre-set the base line tension when the line is shut down for a roll change.

To do this requires that a signal be sent to the control system when a roll change occurs and the operator ensures that the upper and lower limit points set on the transducer are proper for the roll diameter and web tension required.

The second embodiment uses a brake or clutch in the conventional way when the unwind process is restarted after a roll change has occurred, and also uses one or more solenoid valves for switching the web tension control air pressure to all the cylinders.

At the same time, the electronic control means would start to increase the primary base line tension air pressure, until a differential pressure gauge switch has indicated that there was pressure equality with the secondary tension controlling pressure.

After these pressures had become equal, the system would be automatically switched over to the extended range mode for the normal unwinding operation.

The invention is thus broadly directed to a system for controlling the rotary motion of apparatus of the type used in unwinding rolls or webs of sheet material, in which a pressure sensing electrical transducer is coupled to an electromechanical feedback control circuit and mechanism for adjusting the rotary motion of the apparatus for providing a substantially constant surface speed and web tension for the roll of sheet material as the roll diameter changes.

The pressure sensing electrical transducer comprises at least one device for sensing the tension of the moving web and for generating an input electric signal in response to the tension. As a precondition for the correct functioning of the transducer, it is necessary to determine the correct relationship between the tension and speed of the moving web, and the air pressure in the brake drum or cylinder. Once this correlation has been ascertained through known experimental procedures, it is possible to then set the lower, and the upper, pressure limit points on the transducer device, that will correspond to the desired lower and higher web tension and speed levels to be used throughout the unwinding operation of the system.

In one embodiment of the invention, there are two pressure sensing electrical transducer devices with each device sensing the tension of the moving web at a different location along the web. Each device would then generate a separate input electrical signal. These two input electrical signals are then received by an electronic control means which is part of an electromechanical feedback control circuit and mechanism for adjusting the rotary motion of the apparatus to provide the substantially constant surface speed and tension in the web. In this embodiment, there is the dual sensing and adjustment combination based upon the simultaneous use of the two sensing devices. The electronic control means has two controller switches. When it is desired to utilize this dual sensing combination, the two controller switches are placed in the open position.This dual system has the advantage of providing a very accurate and precise method for controlling the air pressure within the base line cylinders and within the fine tuning secondary cylinder.

In another embodiment of the invention, one of the two controller switches is closed, while the other of the two controller switches remains open. This is during the main operating, or unwinding, cycle. This will disconnect one of the two pressure sensing electrical transducer devices, leaving only a single transducer device electrically connected to, and generating an input signal for, the electronic control means. This single sensing embodiment has the advantage that one of the two transducer devices can be repaired, or replaced if necessary, without stopping the system during this time, since the other operable transducer is available to measure the pressure within the system.

In a further embodiment of this invention, the other controller switch is closed while the first controller switch remains open. This is for controlling the initial unwinding start-up primary or base line conditions, whenever a new full roll of material is to be placed, on the stand, to be unwound. This will disconnect the other of the two pressure sensing electrical transducer devices, leaving only a solitary transducer device electrically connected to, and generating an input signal for, the electronic control means. This solitary sensing embodiment has the advantage that it will automatically preset the tension in the primary, or base line, rotary motion means whenever this means has been shut down for changing the roll of material.

In a still further embodiment of the invention, for controlling the initial unwinding startup primary, or base line, conditions to be utilized whenever a new full roll of material is to be placed, on the stand, to be unwound, there is a first solenoid valve and switch connected to the electronic control means, a second solenoid valve and switch connected to the electronic control means, and a differential pressure gauge and switch for measuring the pressure across the first and second solenoid valves and for generating an electric input signal which is transmitted to the electronic control means. This electronic control means will cause the first and second solenoid valves to open, and to remain open, until the pressure across these valves, as well as throughout the system, has equalized.

Two embodiments of a control system in accordance with the invention will now be described by way of example and with reference to the accompanying drawing, in which: Figure 1 shows a schematic view of a first embodiment of the control system and Figure 2 shows a schematic view of a second embodiment of the control system.

In Fig. 1, a motor (not shown), which can be a standard fixed speed AC motor, is utilized to unwind a roll 1 of sheet material on a winding stand 2 into a web 3 of sheet material. The winding stand 2 is the primary, or base line, rotary motion means. Thus, the web 3 of Fig. 1 is in motion around stand 2 and around rollers R1, R2 and R3, the rollers R1, R2 and R3 constituting the secondary rotary motion means.

Within the winding stand 2 is an unwind tension control means 4 which includes a first fluid activated means, or a friction pad cvlinder 5, for controlling the primary, base line tension of the web. Preferably, the fluid system is an air, or pneumatic, system. However, a hydraulic fluid system could also be utilized whenever this is found to be appropriate for the type of winding stand equipment employed. As shown in Fig. 1, more than one tension control means 5 may be present within the winding stand 2 for providing greater accuracy in the control of the base line tension of the web.

A second fluid activated means comprises a web tension regulator means 6 which includes a fluid activated friction pad cylinder 7, which is connected to a brake drum 8 within roller R2. The regulator means 6 provide a secondary, or fine tuning, type of control for the tension of the moving web 3.

In certain cases an electrically activated means, such as an electric brake, can be substituted for a fluid activated brake. This electric brake can be actuated by using electri cally controlled rheostats.

A first sensing means 9 senses the tension of the web within the primary base line rotary motion means of the winding stand 2. Sensing means 9 is an air pressure transducer that senses and displays the air pressure in the cylinder of the base line tension controlling friction pad cylinder 5 and includes a pneumatic differential pressure gauge with a lefthand limit pointer 10 set at the lower air pressure limit and with a right-hand limit pointer 11 set at the higher air pressure limit.

There is also an actual pressure indicating pointer 12, movable in between the limit pointers 10 and 11, and movable to either side beyond the limit pointers 10 and 11. The pressure cylinder pressure read out is shown on scale 1 3. Control knob 1 4 is used to set or to adjust the left, or lower pressure, limit pointer 10 and control knob 1 5 is used to set or to adjust the right, or higher pressure, limit pointer 11.

The sensing means 9 is connected to the tension controlling friction pad cylinder 5 by a pneumatic line 1 6 and senses the web tension by measuring the corresponding air pressure in the line 1 6. The relationship between these variables is one of direct proportion, such that a high air pressure in line 1 6 means that there is a high air pressure in the cylinder 5, which means that the brake shoe of cylinder 5 is pressed more tightly against the brake drum of this cylinder, causing a greater tension in the web. Conversely a low air pressure in line 1 6 means that there is a low air pressure in the cylinder 5, which means that the brake shoe of cylinder 5 is pressed less tightly, or not at all, against the brake drum of this cylinder, causing a lesser tension in the web.

Thus the first sensing means 9 will sense the base line tension of the web 3; and only if the corresponding air pressure is greater than the higher air pressure set by the upper limit pointer 11 will a negative first input electric signal be generated. On the other hand, if the corresponding air pressure is lower than the lower air pressure set by the lower limit pointer 10, then a positive first input electric signal will be generated. If the air pressure is within the higher and lower limits, then no first input electric signal will be generated.

This first signal will be transmitted over the electrical connection 1 7 to an electronic control means 1 8.

A second sensing means 9A senses the tension of the web within the web tension secondary regulator means 6. Means 9A is an air pressure transducer gauge identical to gauge means 9. For this reason, the various component parts of the sensing means 9A will not be numbered and described in addition to the above description of gauge means 9.

However, it is to be understood that wherever necessary, the various features of gauge 9A will be denoted by reference to the corresponding feature of gauge 9, except that "A" will be added to the reference numeral. Thus for example, the left limit pointer 1 0A is that pointer set at the lower air pressure limit of gauge 9A.

The second sensing means 9A is connected to the web tension regulating means controlling friction pad cylinder 7 by pneumatic tubing line 1 9 and and senses the web tension by measuring the corresponding air pressure in the line 19.

If the sensing means 9A is to be used In combination with the sensing means 9, then conduit valve 40 will be closed to disconnect air line 1 9A from means 9A and from air line 1 9. so that the sensing means 9A is unable to measure the air pressure in air line 1 9A.

The relationship between these variables is one of direct proportion, such that a high air pressure in line 1 9 means that there is a high air pressure in the cylinder 7, which means that the brake shoe of brake drum 8 is pressed more tightly against the brake drum causing a greater tension in the web. Conversely, a low air pressure in line 1 9 means that there is a low air pressure in the cylinder 7, which means that the brake shoe of brake drum 8 is pressed less tightly, or not at all, against the brake drum causing a lesser tension in the web.

Thus this second sensing means 9A will sense the secondary line tension of the web 3 as it proceeds past the regulator means 6. If the corresponding air pressure is greater than the higher air pressure set by the limit pointer 1 1A, then a negative second input electric signal will be generated. On the other hand, if the corresponding air pressure is lower than the lower air pressure set by the limit pointer 1 or, then a positive second input electric signal will be generated. This second electric signal will be transmitted over the electrical lead 20 to the electronic control means 1 8. If the air pressure is within the higher and lower limits, then clearly no second input electric signal will be generated.

The elctronic control means 1 8 receives the first input electric signal from the first sensing means 9, and/or receives the second input electric signal from the second sensing means 9A. In response to this first input electric signal, the electronic control means will generate a first input electric signal, while in response to a second input electrical signal, the electronic control means will generate a sec ond output electric signal.

It is to be noted that a positive input signal, received by the control means 18, will cause a positive output signal to be generated while conversely a negative input signal, received by the control means 18, will cause a negative output signal to be generated.

Means responsive to these output signals include an electric motor 21 coupled to a fluid flow pressure regulator, or pump 22. This responsive means is responsive to the first output signal for actuating the first fluid activated tension control means 5. In addition, this responsive means is responsive to the second output signal for actuating the second fluid activated tension control means 7. These fluid activated means are controlled so as to adjust the rotary motion means to provide a substantially constant surface speed and web tension for the sheet material as the material is unwound and withdrawn from the roll which then decreases in diameter.

Whenever the electronic control means 1 8 receives a first input electric signal, the generated first output electric signal is transmitted over lead 23 to turn on motor 21. Simultaneously, another output signal is transmitted over lead 24 to open the ordinarily closed first regulator valve 25. Motor 21 has an output shaft 26 which is coupled to pump 22. When motor 21 is so turned on, pump 22 can be caused to aid air through now open valve 25 to increase the air pressure in the line 27 so as to increase the base line air pressure. if the first output signal from the electronic control means is positive. The other or second regulator valve 29 remains closed so that no air can be added to the system through line 30.

However, if the first output signal is negative, the electric motor 21 will be commanded to rotate the shaft 26 in the opposite direction, causing pump 22 to withdraw air through the open valve 25 to decrease the air pressure in the line 27 so as to decrease the base line air pressure.

Whenever air is added to, or is withdrawn from the system, it flows through a supply conduit 28.

The motor 21 will continue to operate until the air pressure in line 16, which is the same as in line 27, has increased sufficiently, so that pointer 1 2 will have moved clockwise past lower limit pointer 10 to the position shown, or has decreased to such an extent that pointer 1 2 will have moved counterclockwise past the limit pointer 11 to the position shown, respectively. Thus, when pointer 1 2 is between pointers 10 and 11. no output signal will be generated by sensing means 9. The motor 21 will stop and first valve 25 will be closed, since there will be no output signal from the electronic controller 18.

When the electronic control means 1 8 receives a second input electric signal, the generated second output electric signal is also transmitted over lead 23 to turn on motor 21.

However, under these operating conditions, simultaneously another output signal is transmitted over lead 31 to open the ordinarily closed second regulator valve 29. When motor 21 is turned on, pump 22 can be caused to add air through now open valve 29 to increase thr air pressure in the line 30 so as to increase the secondary line air pressure in cylinder 7, if the second output signal from the electronic control means 1 8 is positive.

The first regulator valve 25 remains closed so that no air can be added to the system through line 27.

However, if the second output signal is negative, the electric motor 21 will be commanded to rotate in the opposite direction, causing pump 22 to withdraw air through the open valve 20 to decrease the air pressure in the line 30 so as to decrease the secondary line air pressure in cylinder 7.

The motor 21 will continue to operate until the air pressure in line 19, which is the same as the pressure in line 30, has increased enough so that pointer 1 2A will have moved clockwise past lower limit pointer 1 OA to the position shown, or has decreased so that pointer 1 2A will have moved counterclockwise past upper limit pointer 1 1A to the position shown. Thus, when pointer 1 2A is between pointers 1 0A and 11 A, no input signal will be generated by sensing means 9A. Thus motor 21 will stop and second regulator valve 29 will be closed, since there will be no output signal from the electronic control means 1 8.

The above two described situations are either where sensing means 9 is generating a first input signal, or where sensing means 9A is generating a second input signal, but not where sensing means 9 is generating an input signal simultaneously while sensing means 9A is generating an input signal. Under these conditions, wherein dual input signals are being simultaneously generated, two further modes of operation are possible.

In the first of such modes, both input signals are in the same phase; i.e.-both are positive or both are negative. Thus, if both input signals are positive, then both output signals from the electronic control means will be positive. The electric motor 21 will be energized to rotate regulator 22 in one direction so as to increase the air pressure in line 27 through open valve 25, and will be energized to rotate regulator 22 so as to simultaneously increase the air pressure in line 30 through open valve 29. On the other hand, if both input signals are negative, then both output signals from the electronic control means will be negative.The electric motor 21 will be energized to rotate regulator 22 in the opposite direction so as to decrease the air pressure in line 27 through open valve 25, and will be energized to rotate the regulator 22 so as to simultaneously decrease the air pressure in line 30 through open valve 29.

In the second mode referred to above, one input signal from sensing means 9 is opposite in phase from the input signal from the other sensing means 9A. Thus, one input signal would be positive and the other input signal would be negative. The output signals generated by the electronic control means, under these conditions, would be each 180 out of phase with the other, and would be cancelled out by the time they reached the electric motor 21. Thus motor 21 could not be energized.

The electronic control means contains a hierarchy means, or circuit, that sorts through these conflicting input signals and assigns a top priority to the signal from either sensing means 9 or from sensing means 9A. This priority is decided in advance by the operator of the system, and is programmed into the control settings of control means 1 8 by pressing either the control button switch 32 marked "Path 1" or the control button switch 33 marked "Path 2". Path 1 corresponds to an input signal from sensing means 9A, while path 2 corresponds to an input signal from sensing means 9.

By way of example, if button 32 were pressed, then the input signal from sensing means 9A would be given priority over, and would dominate, the input signal from sensing means 9, if each signal were opposite in phase to the other signal. On the other hand, if button 33 were pressed, then the input signal from sensing means 9 would be given priority over, and would dominate, the input signal from sensing means 9A, if each signal were opposite in phase to the other signal.

The electronic control means 1 8 has a builtin "fail-safe" mechanism whereby one of the two switches 32 or 33 must always be engaged, or else the system cannot be started or will stop operating unless one switch is engaged. Furthermore, the electronic control means 18 is designed such that both switches 32 and 33 cannot be engaged simultaneously. Hence if one switch is engaged, then the other switch will disengage.

The system of Fig. 1 further includes an orifice valve 34 for controlling an air reserve, buffer tank, or reservoir 35 for limiting the rate of fluid pressure change independently from the fluid flow pressure regulator pump 22. The air from reservoir 35 joins the overall system by being connected into the air pressure line 27.

As discussed above, whenever the base line pressure is changed, the electronic control system will respond with a corresponding change to maintain the web tension at its controlled set value. If large, rapid, changes occur in base line pressure, they will have to be matched by correspondingly rapid and large changes in control pressure, if the constant web tension is to be maintained. Such changes could impose a limitation on the ability of the regulator to precisely regulate the web tension. To avoid interfering with the tension control, the electronic controller can be constructed with a built-in restraint on the maximum rate at which the air pressure can be changed.The value of this maximum rate will be adjustable from a dial means 36 mounted on the control means 1 8. This adjustment in range will be achieved by moving the regulator motor 21 a small increment at a time, and adjusting the time interval between increments.

In the first embodiment described above there is a dual sensing and adjustment combi- nation based upon the simultaneous use of sensing means 9A in combination with sensing means 9. This dual system has the advantage of providing a very accurate and precise method for controlling the air pressure within the base line cylinders 5 and within the fine tuning cylinder 7.

The electric control means 1 8 has a main on-off switch 37. Whenever it is desired to utilize the dual sensing combination system with means 9 and 9A functioning simultaneously, first controller switch 38 and second controller switch 39 are each maintained in the open position as shown In Fig. 1.

In another embodiment, first controller switch 38 is closed and second controller switch 39 is open during the main operating, or unwind, cycle. Second controller switch 39 remains open. This will disconnect first sensing means 9 from the electronic control means 18, leaving only second sensing means 9A electrically connected to the electronic control means. At this point it would be necessary to operate switch 32, so that the input signal from second sensing means 9A would be dominant.

Also it is necessary to open conduit valve 40 in air line 19A, in order to connect sensing means 9A with air line 19A. Second sensing means 9A would then measure the pressure both in air line 1 9 connected to cylinder 7 and in air line 1 9A connected to cylinder 5A, which is connected to cylinder 5 to obtain an average pressure reading throughout the system. As discussed above, whenever the average of the measured pressure is outside of the lower limit 1 0A or the upper limit 1 lA, an input signal will be transmitted to the controller 1 8. The closing of first controller switch 38 will cause any output signal from the electronic control means 1 8 to be transmitted not only over lead 23 to the motor 21, but also over leads 24 and 31 to both first and second regulator valves 25 and 29, respectively, so as to open both valves 25 and 29.This will enable the pump 22 either to add air simultaneously to air lines 27 and 30 or to withdraw air simulta neously from air lines 27 and 30, until the average pressure measured by sensing means 9A is modified to be within the lower and upper limits 10A and 11 A. Once the average measured pressure measured by sensing means 9A is modified to be within the lower and upper limits 1 0A and 11 A. Once the average measured pressure is back within these preset limits, no input signal would be generated by means 9A, and control means 1 8 would no longer provide an output signal.

Thus the motor 21 would be stopped and valves 25 and 29 would return to each's normally closed condition.

After the web sheet 3 of sheet material has been unwound from the stand 2, it becomes necessary to remove the core of the roll from the stand and to replace it with a new roll of sheet material. These removal and replacement steps may temporarily distort the air pressure sensing means. In order to adjust the control system so as to compensate for any possible air pressure distortion, first controller switch 38 is opened and then second controller switch 39 is closed during the changing of the roll of material.

The closing of second controller switch 39 while first controller switch 38 remains open will disconnect second sensing means 9A from the control means 18, and will connect sensing means 9 to the control means. At this point, it would be necessary to press operate switch 33, so that the input signal from sensing means 9 would be dominant. Also it would be necessary to close conduit valve 40.

In this embodiment the lower limit 10 and the upper limit 11 are each set at the respective pressure levels that correspond to the appropriate air pressure limit levels, which are the optimum levels for the initial unwinding start-up base line conditions, whenever a new full roll of material is to be unwound. The closing of second controller switch 39 will cause any output signal from the control means to be transmitted over lead 23 to the motor 21 and also over lead 24 to regulator valve 25 only. This will enable the pump 22 either to add air to air line 27 or to withdraw air from air line 27, until the pressure measured by sensing means 9 is modified during the initial start-up of the unwinding to be within the appropriate preset lower and upper limits 10 and 11, respectively.Once the measured pressure is back within these preset start-up limits, no input signal would be generated by means 9, and control means 1 8 would no longer provide an output signal.

Thus the motor 21 would be stopped and valve 25 would return to its normally closed condition.

Once the unwinding operation is properly underway, switch 39 would be opened. Since both switches 38 and 39 are now open, the control system will return to the dual sensing system with means 9 and 9A functioning simultaneously as described above. Switch 32 or switch 33 could then be operated depend ing upon which input signal was to have the priority, as discussed above. Also the lower limit 10 and the upper limit 11 of the first sensing means 9 would be reset for the appropriate pressure levels to be utilized during normal operating unwinding conditions.

The control system shown in Fig. 2 is very similar to that shown in Fig. 1. All features shown in Fig. 2 have a reference numeral with a prefix of "200", however, if an element analogous to that of the control system of Fig. 1, is to be referred to in the following discussion of Fig. 2, then the same reference numeral will be utilized in Fig. 2, except that the prefix "200" will be added to the reference numeral of Fig. 1.

In the second embodiment of the invention shown in Fig. 2, there is a first solenoid valve 250 connected through conduit 227 to the means responsibe to the output signal, namely the fluid flow pressure regulator air pump 222. Valve 250 is also connected to the first fluid activated means or cylinder 205.

A first switch 251 is connected by lead wire 252 to the electronic control means 218.

Switch 251 controls the first solenoid valve by opening and closing the same in response to a third output signal from the electronic control means.

There is also a second solenoid valve 253 connected through conduit 254 to the first solenoid valve 250 and connected to the second fluid activated means 207 through conduit 219. Valve 253 is connected to cylinder 205A through conduit 219A, which contains conduit valve 240. There is a second switch 255 connected by lead wire 256 to the electronic control means 218. Switch 255 controls the second solenoid valve 253 by opening and closing the same in response to a fourth output signal from the electronic control means.

Differential pressure gauge switch 257 is for measuring the pressure across the first and the second solenoid valves. This it does by measuring the pressure in conduit 258 which is the same as the air pressure produced by the pump 222 through line 227. Switch 257 also measures the pressure in conduit 259 which is the same as the air pressure in conduits 219 and 219A, in which conduit valve 240 would be open. This pressure difference is then converted into a third electric input signal which is transmitted to the electronic control means through lead 260.

In Fig. 2, whenever the controller switches 238 and 239 are open, both sensing means 209 and 209A function as dual sensing means and conduit valve 240 would be closed. Whenever switch 238 is closed and switch 239 is open, it would be during the main unwind cycle with sensing means 209 disconnected as discussed above. Here con duit valve 240 would be open.

However, when switch 238 is open and switch 239 is closed, then both sensing means 209 and 209A are disconnected from the electronic control means 218. Substituted for sensing means 209 and 209A during the changing of the roll of material, and during the initial start-up conditions, are the solenoid valves 250 and 253, and the differential pressure gauge switch 257. Here conduit valve 240 would be open.

Switch 257 measures the pressure in conduits 258 and 259. If the pressures are different, then a third electric input signal is conducted to the control means 21 8 through lead 260. The control means 218 sends a third output signal through lead 252 to open the normally closed switch 251 to open the first solenoid valve 250. Also a first output signal is sent to turn on motor 221 and a second output signal opens valve 225, so as to cause pump 222 to increase the air pressure in line 227. Simultaneously, a fourth output signal is sent from the control means 218 through lead 256 to open the normally closed switch 255 to open the second solenoid valve 253.

As discussed above, the fact that the base line pressure will be restrained, under certain conditions, from rapid movement means that the web tension regulating system can no longer be used to rapidly bring the web tension under control when the web line is set in motion.

The embodiment of Fig. 2 is to use the brake in a known way when the process is restarted after a roll change, with two solenoid valves 250 and 253 switching the tension control air pressure to all cylinders.

At the same time, the control means 218 would start to increase the base line tension air pressure in lines 258 and 227 until the differential pressure gauge switch 257 indicated equality with the web tension controlling pressure of lines 259, 219 and 219A.

When these pressures beome equal, the differential pressure switch 257 will no longer generate a third input signal to the control means 218. At this point the control means 218 will no longer generate any output signals, so that motor 221 will stop, valve 225 will close, switch 251 will closed to close solenoid 250 and switch 255 will be closed to close solenoid 253.

Controller switch 239 can again be opened since the initial start-up with a new roll of material has been completed. Since controller switch 218 is also open, both sensing means 209 and 209A will again be connected into the control means 218 and can function as the dual sensing means. Conduit valve 240 would then have to be closed. Either switch 232 or 233 would have to be engaged, as discussed above.

Claims

1. A system for controlling the rotary motion of a web-handling apparatus, for rolls of webs of sheet material, comprising: means for providing rotary motion for said apparatus, a fluid activated means for adjusting said rotary motion means; means for sensing the tension of said web within said rotary motion means and for generating an input electric signal in response to said tension; an electronic control means for receiving said input electric signal from said sensing means, and for generating an output electric signal in response to said input electric signal; and means responsive to said output signal for actuating said fluid activated means to adjust said rotary motion means to provide a substantially constant surface speed and web tension for said sheet material.

2. A system according to Claim 1, wherein said means responsive to said output signal comprises an electric motor coupled to a fluid flow pressure regulator pump.

3. A system according to Claim 1 or claim 2, wherein a first solenoid valve is connected to said means responsive to said output signal and is connected to said fluid activated means, and a first switch is connected to said electronic controller means for controlling said first solenoid valve.

4. A system according to claim 3, wherein a second solenoid valve is connected to said first solenoid valve and to said fluid activated means. and a second switch is connected to said electronic control means for controlling said second solenoid valve.

5. A system according to claim 4, wherein a differential pressure grauge switch is provided for measuring the pressure across said first solenoid valve and said second solenoid valve and for generating another input signal to be sent to the electronic controller.

6. A system for controlling the rotary motion of a web-handling apparatus for rolls of webs of sheet material comprising means for providing rotary motion for said apparatus, said rotary motion means including a primary or base line rotary motion means and a secondary rotary motion means; a first fluid activated means for adjusting said primary or base line rotary motion means; a second fluid activated means for adjusting said secondary rotary motion means; a first means for sensing the tension of said web within said primary or base line rotary motion means and for generating a first input electric signal in response to said tension; a second means for sensing tnsion of said web within said secondary rotary means and for generating a second input electric signal in response to said tension;; an electronic control means for receiving said first and said second input electric signals from both of said sensing means, and for generating a first output electric signal in response to said first input electric signal and for generating a second output electric signal in response to said second input electric signal; and means responsive to said output signals for actuating said fluid activated means to adjust said rotary motion means to provide a substantially constant surface speed and web tension for said sheet material.

7. A system according to claim 6, wherein said means responsive to said output signal comprises an electric motor coupled to a fluid flow pressure regulator pump.

8. A system according to claim 7, wherein said pump comprises a first regulator valve responsive to said first output signal and connected to said first fluid activated means an a second regulator valve responsive to said second output signal and connected to said second fluid activated means.

9. A system according to claim 7 or claim 8 wherein an orifice valve and a reservoir are provided for limiting the rate of fluid pressure change independently from the fluid flow pressure regulator pump.

10. A system according to claim 6, wherein said output signal responsive means is responsive to said first output signal for actuating said first fluid activated means.

11. A system according to claim 6, wherein said output signal responsive means is responsive to said second output signal for actuating said second fluid activated means.

1 2. A system according to any one of claims 6 to 11, wherein hierarchy means is provided for sorting through conflicting input signals from said first sensing means and said second sensing means and for assigning a priority to one of these input signals.

1 3. A system according to any one of claims 6 to 12, herein said electronic controller means further comprises a first controller switch and a second controller switch.

14. A system according to claim 13, wherein said first controller switch is open and said second controller switch is open, such that said first sensing means functions simultaneously with said second sensing means as a dual sensing combination.

1 5. A system according to claim 13 or claim 14, wherein said first controller switch is closed and said second controller switch is open, such that first sensing means will be disconnected from said electroic controller, such that said second sensing means will be connected to said electronic controller for use during the main operating unwind cycle of the system, and such that said electronic control means will send the same output signal to both said first regulator valve and said second regulator valve.

1 6. A system according to any one of claims 1 3 to 1 5 wherein said first controller switch is open and said second controller switch is closed, such that said second sensing means will be disconnected from said electronic control means, such that said first sensing means will be connected to said electronic control means, so as to automatically preset the tension in the primary or base line rotary motion means whenever the primary or base line rotary motion means has been shut down for a roll change.

1 7. A system according to claim 6, and further comprising a first solenoid valve connected to said means responsive to said output signal and connected to said first fluid activated means, and a first switch connected to said electronic control means for controlling said first solenoid valve.

1 8. A system according to claim 1 7 and further comprising a second solenoid valve connected to said first solenoid valve and connected to second fluid activated means, and a second switch connected to said electronic control means for controlling said second solenoid valve.

19. A system according to claim 18, further comprising a differential pressure gauge switch for measuring the pressure across said first solenoid valve and said second solenoid valve and for generating another input signal to be sent to the electronic control means.

20. A system according to claim 6, wherein said electronic control means further comprises a dial means for adjusting the maximum rate at which the air pressure can be changed.

21. A system for controlling the rotary motion of apparatus of the type used in processing rolls or webs of sheet material comprising compnslng means for providing rotary motion for said apparatus; an electrically activated means for adjusting said rotary motion means; means for sensing the tension of said web within said rotary motion means and for generating an input electric signal in response to said tension; an electronic controller means for receiving said input electric signal from said sensing means, and for generating an output electric signal in response to said input electric signal; and means responsive to said output signal for actuating said electrically activated means to adjust said rotary motion means to provide a substantially constant surface speed and web tension for sheet material.

22. A system for controlling the rotary motion of a web-handling apparatus, substantially as hereinbefore described and with reference to Fig. 1 or Fig. 2 of the accompanying drawing.