Claims
- 1. A web tensioning device for providing tension to a moving web, said device comprising:
- an idler roller disposed in contact with the web, said roller having first and second ends;
- air spring means attached to said roller for urging said roller into said web and providing a predetermined distributed force to the web while enabling said roller to rotate about its rotational axis;
- means for supplying pressurized air to said air spring means wherein said means for supplying includes a mechanical actuator contacted by said air spring means when the pressure of said web against said roller results in compression of said air spring means to a predetermined low limit; and
- means for venting pressurized air from said air spring means, said means for venting releasing pressurized air from said air spring means when said roller is disposed toward the web by said air spring means in excess of a predetermined high limit,
- said air spring means including a bracket having two receptacles wherein the first and second ends of said roller are rotatably retained therein, and an air stroke actuator attached to said bracket and pneumatically connected to said means for supplying and said means for venting,
- said mechanical actuator being attached to said bracket.
- 2. The device of claim 1 including a linear bearing attached to said bracket to define a path along which said bracket moves in response to said air stroke actuator, said linear bearing also reducing friction in moving said roller to increase and decrease web tension.
- 3. A web tensioning device for providing tension to a moving web, the device comprising:
- a roller disposed in contact with the moving web, said roller having a first end and a second end;
- a first fluid spring having an expandable cavity at least partially filled with a fluid attached to and supporting said first end of said roller against the tension in the moving web;
- a second fluid spring having an expandable cavity at least partially filled with said fluid attached to and supporting said second end of said roller against the tension in the moving web;
- a conduit having a first end in fluid communication with said cavity of said first fluid spring and a second end in fluid communication with said cavity of said second fluid spring; and
- said cavity of said first fluid spring, said cavity of said second fluid spring and said conduit together define a sealed chamber, wherein said conduit permits said fluid to shift between said first fluid spring and said second fluid spring in response to changes in the tension across the web.
- 4. The web tensioning device of claim 3 wherein:
- said fluid is a gas;
- said first fluid spring is pneumatic; and
- said second fluid spring is pneumatic.
- 5. The web tensioning device of claim 4 further comprising:
- a first bracket attached to said first end of said roller and said first fluid spring, said first bracket including a linear bearing substantially restricting said first end to movement along a first line in response to expansion and contraction of said first fluid spring; and
- a second bracket attached to said second end of said roller and said second fluid spring, said second bracket including a linear bearing substantially restricting said second end to movement along a second line substantially parallel to said first line in response to expansion and contraction of said second fluid spring.
- 6. The web tensioning device of claim 5 wherein said cavity of said first fluid spring, said cavity of said second fluid spring and said conduit together define a sealed chamber, and the device further comprising:
- control means attached to said first and second fluid springs for supplying pressurized gas to said chamber when one of either said first end or said second end move to a predetermined low limit and for venting gas from said chamber when one of either said first end or said second end moves to a predetermined high limit.
- 7. The web tensioning device of claim 6 wherein:
- said control means includes at least one vent valve for venting gas from said chamber and at least one supply valve positioned between a pressurized gas source and said chamber, said control means further including mechanical actuator means for opening said at least one vent valve when one of either said first end or said second end moves to said predetermined high limit and for opening said at least one supply valve when one of either said first end or said second end move to said predetermined low limit; and
- wherein said at least one vent valve and said at least one supply valve are biased closed.
- 8. The web tensioning device of claim 7 wherein:
- said control means includes a first vent valve in fluid communication with said cavity of said first fluid spring, a first supply valve positioned between a pressurized gas source and said cavity of said first fluid spring, a second vent valve in fluid communication with said cavity of said second fluid spring, a second supply valve positioned between said pressurized gas source and said cavity of said second fluid spring; and
- said mechanical actuator means includes a valve opening arm attached to each of said first vent valve, said first supply valve, said second vent valve and said second supply valve, and includes a first low limit trip dog and a first high limit trip dog connected to and moving with said first end of said roller, and further includes a second low limit trip dog and a second high limit trip dog connected to and moving with said second end of said roller; and
- wherein said first low limit trip dog contacts said valve opening arm of said first supply valve when said first end moves to said low limit, said second low limit trip dog contacts said valve opening arm of said second supply valve when said second end moves to said low limit, said first high limit trip dog contacts said valve opening arm of said first vent valve when said first end moves to said high limit, and said second high limit trip dog contacts said valve opening arm of said second vent valve when said second end moves to said high limit.
- 9. A manufacturing apparatus includes a supply roll that provides a web to the manufacturing apparatus, and wherein the web moves at a predetermined velocity over a cylindrical roller and subsequently into the apparatus, the web having tension unevenly distributed across its width upstream from the cylindrical roller, the improvement comprising:
- fluid means for movably supporting the ends of the cylindrical roller in a direction substantially perpendicular to the direction of movement of the web; and
- said fluid means further being for adjusting the position of said cylindrical roller to redistribute the tension uniformly across the web, wherein said fluid means adjusting the cylindrical roller in response to a force applied by the moving web to a first end and a second end of said cylindrical roller.
- 10. The improvement of claim 9 wherein:
- said fluid means for movably supporting is pneumatic.
- 11. The improvement of claim 10 wherein:
- said roller has a first end and a second end;
- said fluid means for movably supporting includes a first bracket attached to the apparatus and having a first bearing movably attached thereto and a second bracket attached to the apparatus and having a second bearing movably attached thereto, and includes a first pneumatic spring attached between said first bracket and said first bearing, and further includes a second pneumatic spring attached between said second bracket and said second bearing; and
- wherein said first end of said roller is supported by said first bearing and said second end of said roller is supported by said second bearing.
- 12. The improvement of claim 11 wherein:
- said first pneumatic spring is in fluid communication with said second pneumatic spring to allow gas to shift therebetween, thereby coupling the movement of said first end of said roller to said second end of said roller.
Parent Case Info
This application is a continuation of application Ser. No. 08/061,221, filed May 12, 1993, now abandoned.
US Referenced Citations (6)
Foreign Referenced Citations (1)
Number |
Date |
Country |
723037 |
Dec 1965 |
CAX |
Continuations (1)
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Number |
Date |
Country |
Parent |
61221 |
May 1993 |
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