TENSIONER FOR CONTINUOUS WEB REWIND ROLL

Abstract

A tensioner for controlling tension in a continuous web being wound onto a rewind roller after the web is processed, for example after printing on labels carried on the web. The tensioner receives the web from a processor and has a slack sensor between the processor and the input of the tensioner. The slack sensor indicates when the slack is a selected minimum, and the web is clamped by the tensioner. After a selected time, which is before the slack sensor indicates a maximum slack is present, the motor driving the rewind roller is stopped and the web is unclamped. After unclamping the web, the rewind roll is again driven at a speed to take up more of the web than that which is driven by the processor, to wrap the web around the core until the slack sensor indicates the slack in the web is at a minimum.

Description

BACKGROUND OF THE INVENTION

The present disclosure relates to a system for controlling the tension on a web that is being wound onto a rewind roll from the output of a processor, such as a printer, through which the web has passed. The web is a continuous strip that may carry labels or other materials that are printed.

Label printers, in particular, have a supply roll of a continuous web or substrate carrying the labels and the web is fed through the printer. After the label is printed, the web is wound onto a rewind roll so that the printed labels can be removed from the web for use. It is important that the web is tightly wound on the rewind roll. It is desirable that the web is not pulled by external tension as it passes through the printer, to avoid printing problems. Also, the web should be wound so that the rewind roll has a smooth, uniform edge.

SUMMARY OF THE INVENTION

The present disclosure relates to a web rewind system for controlling the tension with which a web or substrate is rewound onto a roll. The rewinding is done in a manner that ensures the web or substrate is tightly wound on the rewind roll, and which also ensures that the tension in the web at the rewind roll does not cause external tension on the web portion that is in the processor or printer. It is known to have an adjustable torque drive on a web rewind roll so that the amount of tension created in a web being wound onto the rewind roll can be controlled.

The present device is a web control that will receive the web after the web has passed through a processor, as shown a printer, and before the web is wound onto a rewind roll, so that periodically the web can be clamped and the loops of the web on the rewind roll are tightened down onto the core by driving the core without causing any increase in tension in the web as it exits the printer. The present rewind tension control device is compact and easy to use, and the web can be tightly wound on the rewind roll with a lower initial wrap tension than with previous tension controls. Temporarily clamping the continuous web or substrate and controlling the motor driving the rewind roll to continue to rotate creates tension in the web between the clamp point and the rewind roller, and web material previously wound or looped on the roll tightens on itself. Preferably, only a short length of web material is permitted to wrap loosely onto the rewind roll before clamping and tightening, so the slack in the form of loose loops on the rewind roll is easily taken up.

Rewind rolls can be wound with a web until the roll is quite large, for example, up to a twelve inch outside diameter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a typical printer for printing on a label held on a continuous substrate or web, and having a rewind roll positioned to receive the web from a tensioner made according to the present disclosure;

FIG. 2 is a sectional view of the tensioner and rewind roll taken along line 2-2 in FIG. 6 with a web clamp in an open position;

FIG. 3 is a view taken on the same line as FIG. 2, with a web clamp in a clamping position;

FIG. 4 is a side elevational view of the tensioner of FIG. 2 taken from an opposite side of that shown in FIG. 1;

FIG. 5 is an enlarged view of the mounting of a slack sensing arm and sensor shown in FIG. 4; and

FIG. 6 is a view taken along line 6-6 in FIG. 1 with parts removed to show inner workings of a web clamp.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1 illustrates an overall side view of a printer 10 that prints onto items such as labels held on a continuous substrate or web 12 unwound from a supply roll 14, and utilizing a rewind roll web tensioner 28 of the present disclosure. As shown, printer 10 of conventional design is provided with the web or substrate 12 carrying items to be printed, such as labels, and the web is removed from a supply roll 14 mounted on a suitable support 16. The web 12 is fed across a printer infeed section 18, into the interior of the printer 10 to pass under a print head shown schematically at 20. The web is driven by at least one pair of printer feed rolls 22, which are driven by a motor 24 that is part of the printer control system which is controlled by a programmable printer controller 26.

The web 12 is fed from the feed rolls 22 to exit the printer 10, and then it passes to an input of web tensioner 28, and then is wound onto a rewind roller assembly 30 that includes a central core 32 on which the web is wound. The core 32 is supported on a mandrel 31.Side guide plates 33 of roller assembly 30 are spaced apart and supported on the mandrel 31. The web fits between guide plates 33. The rewind roller assembly 30 is driven by a suitable variable torque output motor shown schematically at 34. The output torque of motor 34 is electronically adjustable in a known manner, so that the drive torque for the core 32 can be adjusted from a torque adjustment control 36. Adjustable torque output motors are commercially available.

The tensioner 28 includes guides for guiding movement of the web, and has a “dancer” roll, or slack sensing roll, held in a slack sensor assembly 38. The slack sensor assembly 38 includes a pair of pivoting arms 40, as can be seen in FIG. 5 for example, and a free rolling dancer roll 42 mounted onto and extending between the outer ends of the arms 40. The arms 40 are pivotally mounted on suitable shafts 44 to side walls of a housing 46 for the tensioner.

The dancer roll 42 moves up and down as the slack of the web length between the printer and an infeed to the tensioner forming a loop 13 changes, causing the arms 40 to pivot from an upper operational position shown in solid lines in FIG. 2 to a lower operational position shown in dotted lines in FIG. 2. The slack sensor assembly 38 thus senses the slack in the web 12 at the input or infeed side of the tensioner 28 as the slack loop 13 moves between these two positions. The arms 40 and roller 42 are not spring loaded, and gravity provides the amount of force needed for sensing slack in the web 12.

As can be seen in FIG. 2, the web 12 is fed to an input side or infeed of the tensioner and into the interior of the tensioner housing 46, and passes over a first idler guide roller 48 that is rotatably mounted on the side walls of the housing 46 on suitable bearings. The first idler guide roller 48 is also shown in FIG. 6.

The web 12 passes underneath a guide plate 52, and underneath an upper clamp pad 54 that is carried by a portion of the guide plate 52. The guide plate 52 is held in the housing in a suitable manner. Additionally, there are guide plates 56 in the housing 46, that, while threading the web, guide it along the bottom side of a second idler guide roller 58 that is also suitably rotatably mounted between side walls of the housing 46. A lower guide plate 60 is provided below the web 12 to guide the web if it is slack, while threading the web. The rollers 48 and 56 define the path of the web when the web is under tension while winding or tightening the web on the rewind roll.

The upper clamp pad 54 operates in connection with a lower clamp pad 62 that is below the web 12, and aligned with the upper clamp pad 54. The clamp pads together form a web clamp or web restraint that prevents longitudinal, lineal movement of the web 12. The guide plate 52 and the upper clamp pad 54 extend transversely between the side walls of the housing 46.

The lower clamp pad 62 likewise extends across the tensioner between the side walls of the housing 46 and is formed as part of a plate-like lower clamp pad bracket or plate 64 that is slidably guided for limited vertical movement. As can be seen in FIG. 6, the lower clamp pad bracket 64 is spring loaded in an upward direction tending to move the lower clamp pad 62 toward the upper clamp pad 54, using suitable springs 66 on opposite ends of the bracket 64. It can be seen that the lower clamp pad bracket has slots that are guided along suitable guides 68 held relative to the housing 46.

The lower clamp pad bracket 64 is spring loaded toward the upper clamp pad 54 with springs 66 to a web clamping position. A cam 70 that is driven from an output shaft 80 of a clamp motor 82 can be rotated to move the lower clamp pad 64 to an open position. The cam 70 aligns with a flange 84 that is formed on the clamp pad bracket 64, so that as motor 82 rotates the cam lobe will engage the flange 84 and move the lower clamp pad bracket 64 against the force of the springs 66 to the open position that is shown in FIG. 2 with the lower clamp pad 62 spaced from upper clamp pad 54. When the cam 70 is rotated so it moves away from the flange 84 the springs 66 urge the lower clamp pad 62 against the underside of the web 12 to push the web 12 up against the upper clamp pad 54 in a web clamping position shown in FIG. 3.

When the web 12 is clamped as shown with the clamp pads in the position of FIG. 3, the web 12 on the input side of the tensioner 28 cannot be moved to be rewound onto the rewind roller, but is held securely. When the rewind roller is driven by the torque adjustable motor with the web clamped, any loose loops of web will be tightened down onto the core 32 and previously tightened loops of web 12 forming a rewind roll, and a tension is created in the web 12 between the clamp 61 and the loops of the web on the rewind roller core 32. Therefore, any loose loops on the core or on a partially formed roll of web material will be drawn tight, to form a tight winding around the core 32 as a function of the torque of motor 34 driving the core. It can be seen that since the clamp pads 54 and 62 operate to securely hold the web, any tension in the web between the clamp 61 and the rewind roller 30 will not increase the tension on the length of the web 12 between the printer 10 and the tensioner 28 which forms slack loop 13. This means that any tension load from driving the rewind roll will not tend to pull the web through the printer, which can disrupt the printing function and cause misprints.

The desired positions of the dancer roll 42 are sensed to provide signals indicating a desired minimum and maximum slack in the web length between the printer output side and the tensioner. When there is slack less than the minimum, the rewind roller will continue to rotate after the clamp pads 54 and 62 separate until the roll 42 reaches an upper operational position where the slack at the infeed of the tensioner is a minimum. When the web is clamped and the rewind roll is tightened, the slack will increase because the web continues to be driven through the printer, and the dancer roll will reach a lower operational position where the slack loop 13 is at an operational maximum. The rewind roller is driven at a speed to provide a lineal speed of movement of the web greater than the lineal speed of movement of the web through the printer to reduce the slack in the web length between the printer and the infeed of the tensioner during operation when the web is unclamped. The dancer roll 42 will then move between the two different operational positions of arms 40, including the lower operational position (maximum slack) which is illustrated in dotted lines in FIGS. 2 and 3, and an upper operational position indicated in solid lines in FIGS. 2 and 3, which is reached as the slack reduces while the rewind motor is running and the web is unclamped.

When the tension in the web 12 between the printer 10 and the tensioner 28 is such that the web lifts the dancer roll 42 to the position shown in solid lines in FIG. 2, the rewind motor will be stopped and the clamp 61 closed. Once the clamp 61 is closed, the rewind motor 34 is started again to tighten the web lengths or loops on core 32. The printer continues to drive the web toward the tensioner, so the slack loop 13 increases in size while the rewind roll is tightened, and the dancer roll 42 thus moves down.

The two operational positions of the dancer roll 42 are sensed by arm position sensors shown in FIGS. 4 and 5. One end of shaft 44 carries a sensor target disc 90 that is in the form of a part circular disc. The target disc 90 is associated with two individual sensors, 92 and 94, mounted on the tensioner to signal selected pivotal positions of the arms 40. The sensors are each optical sensors that have a light source and a receiver that are spaced apart, and the disc 90 will pass between the light source and receiver of each sensor as the arms 40 move between sensed low and high positions. The sensors include a low operational position sensor 92 and a high operational position sensor 94 to provide signals when the sensor beam from the respective sensor is no longer blocked by the disc 90. In other words, the edges of the disc 90 determine the sensed arm positions. As shown in FIG. 5, the disc 90 and the arms 40 are in the dancer roll low operational position, and the edge 90B of disc 90 (behind the one part of sensor 92 in FIG. 4) has unblocked the beam from the light source of sensor 92 from the receiver of that sensor, or in other words has permitted light to strike the receiver. The sensor 94 senses when an edge 90A of the disc 90 has unblocked the sensor beam of sensor 94 so the light will strike its receiver as the arms 40 move up in direction as indicated by arrow 96 in FIG. 4. Signals are thus provided to controller 37 indicating the two operational positions of the arms 40 and dancer roll 42.

Additionally, the clamped and operational positions of the lower clamp pad 62 and the lower clamp pad bracket 64 are sensed by a sensor 98 that provides a signal when a flag 100 attached to the lower clamp pad bracket 64 is aligned with the sensor. The signal indicating the position of the bracket 64 and the lower clamp pad 62 is provided to a controller 37 to indicate whether the web 12 is clamped or free to move. The controller 37 controls the interaction of web tensioner 28 and the operation of the rewind motor 34.

When the printer and rewind system shown in FIG. 1, for example, is to be loaded with a web 12 carrying printer labels, which are provided from a supply roll 14, the printer 10 can be threaded in a normal manner. The arms 40 and the dancer roll 42 are moved to an inoperative raised position which is shown by the dotted lines in FIG. 1. In this position, the edge 90A of flag or disc 90 is moved away from the light beam of the sensor 94 and the receiver of the sensor provides a signal so a section of a timer 35 will start timing. If the light is still received by the receiver after a selected sensor time period, for example 8 to 10 seconds, the drive motor 34 for the rewind roll is stopped by controller 37 and not started again until the arms 40 are moved back to operating positions. The cam 70 also is moved under control of controller 37 to its position so clamp 61 is open and not clamped.

The continuous web or substrate 12, such as label stock, is threaded through the tensioner, as shown in FIG. 2, over the guide roller 48, between the upper and lower clamp pads 54 and 62, and under the guide roller 58. The end of the web is fastened in a suitable manner to the core 32 of the rewind roller.

When this is done, the arms 40 and the dancer roll 42 are moved to engage the web 12, which forms a slack loop 13 and the sensor 92 indicates the disc 90 is no longer blocking its light beam, the rewind system can be operated. The movement of the arms 40 to the lower operational position will thus automatically start the rewind motor 34 through the controller 37, to wrap the web around the core 32 at a speed faster than the web is fed out of the printer or other device with which the tensioner is used. The web 12 is moved so that the slack loop 13 lifts the dancer roll 42 high enough so that the position sensor 94 signals that the dancer roll 42 is in the upper operational position. The rewind motor will be stopped by the controller 37 in response to this signal, and the tensioner clamp motor will be started to drive the cam 70 so the lower clamp pad bracket is moved upwardly under the spring load from springs 66 until the flag 100 moves far enough so that the lower clamp position sensor 98 indicates to the controller that the clamp bracket 64 is raised. At this point, the lower clamp pad 62 will have moved web 12 against the upper clamp pad. This clamps the web and holds it in position, as shown in FIG. 3. The clamp used is to hold or restrain the web that is coming from the printer from longitudinal movement so it does not wind around the outside of the rewind roll.

The variable torque motor 34 for the rewind roll 30 will then be turned on, thereby tightening the coils or loop of the web that have been loosely wrapped around the core 32, by allowing the core to be rotated and the wraps of web to slip upon themselves and tighten onto the core as the web is held from longitudinal movement by the clamp 61.

The rewind motor 34 is timed as it runs to tighten the loops or wraps with a section of timer 35 in controller 37, and after the clamp 61 is closed, the motor 34 will run for a set period of time, which is dependent upon the speed of the web 12 as it is fed out of the printer 10, and the movement or pivoting of the arms 40 for the dancer roll. The time period for running motor 34 for tightening the wraps or coils of the web on the core is set so that the rewind motor will stop before the web length between the printer and tensioner forming slack loop 13, which is being fed by the printer, becomes slack enough for the dancer arms 40 and roller 42 to reach the lower operational position, as sensed by the sensor 92. In a typical system the tightening time of running the motor 34 may be under 1 second. While, as shown, the motor 34 stops after a set period of time, the motor also could be stopped by a third sensor sensing the position of the arms 40 to signal when the arms are near, but not yet at, the lower operational position.

When the rewind motor 34 is stopped by controller 37 after the set time period for tightening the web loops or wraps on the rewind roller (or after a signal from a third sensor), the tensioner clamp motor 82 will be started by the controller to turn the cam 70 to release the clamp 61. The sensor clamp position sensor changes states again, as sensed by the flag 100 and the sensor 98. The cam 70 will have moved the lower clamp pad 62 away from the upper clamp pad 54 to the position shown in FIG. 2 to release the web.

After the cam 70 has moved the lower clamp pad 62 away from the upper clamp pad 54, and the rewind motor has not yet started again, the slack loop 13 increases and a signal from sensor 92, indicating the dancer roll 42 has reached it lower operational position will be received by the controller 37. Motor 34 for the rewind roll will again be started to wind the web fed from the printer around the rewind roller core at a lineal speed of the web greater than the lineal speed of the web fed from the printer, until the web slack loop 13 reduces and the web again lifts the dancer arms 40 and the dancer roll 42 high enough so the dancer roll upper operational position sensor 94 provides an upper position signal to the controller. The clamp motor 84 will again be energized to turn the cam 70 to permit the lower clamp pad 62 to move up against the upper clamp pad 54 under the spring force to hold or restrain the web or substrate from moving, and the process then repeats.

While the present discussion has dealt with a web that is carrying labels to be printed, and used in combination with a printer, the tensioner can be utilized for controlling rewind tension in a continuous web regardless of what process the web undergoes, to ensure that a continuous web is wound efficiently onto a rewind or take up roller. The rewind roller is capable of exerting a set tension in the web, based upon the output torque of the motor that is driving the rewind roller, in order to have the loose loops or wraps periodically tightened down onto the core and any previous wound wraps forming the rewind roll. This insures a tight rewind roll, and keeps the roll usable for easily removing labels or other items that might be on the web that has been re-wound.

The system is preferably set so that when the rewinding is first started, and the rewind roll of printed web is small, only approximately 12 inches length of the web will be passed through the tensioner before the web is clamped and the rewind roller tightens the loose loops or wraps down onto the core. The function of restraining the web from longitudinal lineal movement and tightening down the lengths of the web forming loops or wraps on the rewind roll in short intervals insures that the web will not have to be placed under excessive tension in order to try to tighten down several loops or wraps of the web on the rewind roller, especially if the web is non-slippery in nature. As the rewind or take-up roll of web and printed labels gets larger, the clamping or restraining of the web to permit tensioning the web wrapped on the rewind roll can be activated and the rewound web tightened before a full wrap is made on the rewind roll. The wraps of web are thus kept tight without exerting a high torque on the rewind roller.

The dancer roll 42 is illustrated as being mounted on two pivoting arms, but can be mounted to cantilever from one arm, or can be mounted in a guide or guides to slide up and down between its desired positions as it senses slack in the web between the printer and the tensioner 28.

When there is no web present at the infeed of the tensioner 28, that is between the printer and the tensioner, the dancer roll 42 and arms 40 will move to or past the lower operational position and the edge 90B of disc 90 clears the lower operational position sensor 92 so light from the sensor light source is received by the receiver of the sensor, and again the controller 37 and a section of timer 35 would time how long the light source of sensor 92 was received by its receiver, and if the beam of light was not blocked by the disc 90 after a selected sensor time period for sensor 92, for example, again, 8 to 10 seconds, the motors 34 and 82 would be kept off by controller 37 until the tensioning system was reloaded with a web. The sensor time period for sensor 92 can be different from the sensor time period for sensor 94, if desired.

While a direct acting clamp 61 is disclosed as the web restraint, other web restraints that prevent movement of the web to hold the web from wrapping around the rewind roll, and which will permit rotating the rewind roll core after the web movement is restrained, can be used.

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

Claims

1. A tension control device for a continuous web to be wound onto a roll having a motor for rotatably driving the roll for winding the web, the tension control device comprising:

a web restraint operable to prevent movement of the web;

a control to initiate the motor to drive the roll to tighten portions of the web on the roll when the web restraint is operated to prevent movement of the web; and

a release mechanism to release the web restraint to permit movement of the web when the roll is rotatably driven by the motor.

2. The tension control device of claim 1 including a processor to drive the web to an infeed of the tension control device, a web slack sensor sensing slack in the web being driven to the infeed, the web restraint being operated for preventing movement of the web when the web slack sensor indicates a selected slack in the web, and a second sensor to provide a signal starting the motor for driving the roll when the web is prevented from movement.

3. The tension control device of claim 2 wherein the web slack sensor provides a second signal indicating that the slack in the web is a selected maximum, the motor being timer controlled to stop driving the roll before the web slack sensor provides the second signal.

4. The tension control device of claim 2, wherein the processor drives the web to the infeed at a first lineal speed, and the motor drives the roll at a speed to provide a lineal speed of the web greater than the first lineal speed when the web restraint is released.

5. The tension control device of claim 2, wherein the web slack sensor comprises a rotatable sensing roll mounted to move relative to a path of movement of the web between the processor and the infeed, said sensing roll being moved by the web between a first position indicating at least a reduced slack in the web, and a second position indicating a maximum desired slack in the web.

6. The tension control device of claim 5, wherein said sensing roll is mounted on an arm, said arm being pivoted relative to the tension control device to permit the sensing roll to move in an arc as the sensing roll moves between the first and second positions.

7. The tension control device of claim 1, wherein the web restraint comprises clamp pads that are spaced apart, with the web passing between the clamp pads, and wherein the release mechanism moves one of the clamp pads away from the other clamp pad.

8. A tension control device of claim 1 further comprising a timer to control the motor to rotate the roll for a set period of time after the web restraint has been operated to prevent movement of the web.

9. The tension control device of claim 1, and further comprising a controller receiving a signal indicating that a web length at an infeed of the tension control device is slack and thereafter operating the release mechanism to release the web restraint and to start the motor to drive the roll.

10. The tension control device of claim 9 including a web slack sensor providing a signal to the controller when the slack in the web length at the infeed of the tension control device is at a selected minimum, to operate the clamp to prevent movement of the web, and to initiate the motor to drive the roll to tighten portions of the web on the roll.

11. The tension control device of claim 9 wherein said motor drives the roll, after the web restraint is released by the release mechanism such that the web moves at a lineal speed which reduces slack in the web length at the infeed of the tension control device.

12. The tension control device of claim 1, wherein said web restraint comprises a clamp and further comprising guides for guiding the web through the clamp and to the roll.

13. A tension control system for regulating the tension in a continuous web as the web is wound onto a rewind roll from a printer driving the web, the printer having a web feed driving the web through the printer, the tension control system including a tensioner assembly between the printer and the rewind roll associated with the web, said tensioner assembly having a slack sensor for sensing slack in the web between the printer and the tensioner assembly, and a web restraint to prevent movement of the web around the rewind roll, a motor to drive the rewind roll to rewind a web thereon when the web restraint is positioned to permit movement of the web, and to tighten the web onto the roll at selected intervals when the web is prevented from movement around the rewind roll.

14. The tension control system of claim 13, and a slack sensor operable to sense a slack in the web between the printer and the tensioner assembly, sensors to sense a position of the slack sensor indicating the amount of slack in the web between the printer and tensioner assembly, and a controller to periodically cause the motor to drive the rewind roll to rewind the web onto the rewind roll when the web is permitted to move by the web restraint, and to cause the motor to rotate the rewind roll to tighten loose lengths of the web on the rewind roll when the web is prevented from movement from the printer to the rewind roll.

15. The tension control system of claim 13 wherein said web restraint comprises a clamp and further comprising a clamp control to release the clamp and permit the web to be rewound on the rewind roll when the slack in the web between the printer and the tensioner assembly is indicated as being a selected amount, and to operate the clamp to clamp the web when the slack sensor indicates when the slack of the web between the printer and the tensioner assembly is at a selected minimum amount.

16. The tension control system of claim 13, wherein said web restraint comprises a clamp, a spring to spring load the clamp to a clamping position to restrain the web, and a release mechanism to release the clamp against the spring load in response to a signal from the slack sensor.

17. A method of controlling wrapping of a an elongated web onto a rewind roll, comprising driving the web longitudinally lineally from a processor, providing a driven rewind roller to take up the elongated web from the processor, providing a web restraint to selectively restrain the web from longitudinal lineal movement, periodically restraining the web and driving the rewind roller while the web is restrained to tighten lengths of the web previously wound on the rewind roller.

18. The method of claim 17, including sensing slack of the web between the processor and the web restraint to provide signals to selectively restrain and release the web for longitudinal lineal movement at selected intervals.

19. The method of claim 18 including driving the rewind roller at a speed such that the web has a lineal speed when the web is released that is greater than a lineal speed of the web as driven by the processor.

20. The method of claim 17 including providing a clamp for forming the web restraint, sensing slack of the web between the processor and the clamp and clamping the web with the clamp to restrain longitudinal lineal movement of the web when slack of the web between the processor and the clamp is a selected minimum.

21. The method of claim 20 including sensing when slack of the web between the processor and the clamp is at a selected maximum after the web is clamped by the clamp, stopping the drive to the rewind roller prior to the time slack of the web reaches its selected maximum, and releasing the clamp to permit the web to move when the selected maximum slack is sensed.

22. The method of claim 21 and further comprising driving the rewind roller after the clamp is released until slack of the web between the processor and the clamp is sensed to be at the selected minimum.