Web tensioning with adjustable counterweights for controling the spacing of imprints

Claim 2

Sheet-handling apparatus comprising: a support; a printing assembly on said support including a pair of rotatable rolls in proximity to each other and disposed for receiving therebetween a flexible sheet movable along a path of travel transverse to said rolls, whereby the sheet is printed as it moves between the rolls; a first dancer arm on said support upstream of said printing assembly with respect to said path, said first dancer arm being disposed for engaging the sheet to apply a first tension force thereto acting in the upstream direction thereof; a second dancer arm on said support downstream of said printing assembly and disposed for engaging the sheet to apply a second tension force thereto acting in the downstream direction thereof, each of said dancer arms being mounted intermediate its ends for free pivotal movement about a horizontal axis and having a sheetengaging roller at one of its ends and an adjustable counterweight at its opposite end; first sheet drive means upstream of said first dancer arm for moving the sheet in the downstream direction; and second sheet drive means downstream of said second dancer arm for moving the sheet in said downstream direction.

Claim 3

Sheet-handling apparatus comprising: a sheet printing assembly adapted to be disposed in the path of travel of a movable sheet; means upstream of said assembly and engageable with said sheet on said path for applying a first tension force to the sheet; means downstream of said assembly and engageable with said sheet for applying a second tension force to the sheet; each of said upstream means and said downstream means including an arm mounted intermediate its ends for free pivotal movement about a horizontal axis, roller means on one end of the arm for engaging the sheet, and an independently adjustable counterweight on the opposite end of the arm, whereby the difference between the weight of said roller means and the counterweight will define a force exerted on the sheet to provide the respective teNsion force; and drive means independent of said upstream means and of said downstream means for moving said sheet in one direction along said path.

Claim 4

Sheet-handling apparatus comprising: a sheet printing assembly adapted to be disposed in the path of travel of a movable sheet; means upstream of said assembly and engageable with said sheet on said path for applying a first tension force to the sheet; means downstream of said assembly and engageable with said sheet for applying a second tension force to the sheet; each of said upstream means and said downstream means including an arm mounted intermediate its ends for free pivotal movement about a horizontal axis, roller means on one end of the arm for engaging the sheet, and an independently adjustable counterweight on the opposite end of the arm, whereby the difference between the weight of said roller means and the counterweight will define a force exerted on the sheet to provide the respective teNsion force; and drive means independent of said upstream means and of said downstream means for moving said sheet in one direction along said path.

Claim 5

In a method for substantially instantaneously adjusting the speed of a sheet passing a sheet-handling station to maintain the spacing between adjacent transverse print lines imprinted on the sheet at said station constant over the length of the sheet, the method including the steps of feeding the sheet towards the sheet-handling station; passing the sheet through the sheet-handling station; withdrawing the sheet from the handling station; printing spaced lines on said sheet as it moves through said station, the lines being spaced in a direction transverse to the movement of the sheet; and adjusting the tension applied to the sheet at the upstream and downstream positions of the station, the adjustment of the tension being performed by means upstream of said station and engageable with the sheet for applying a first tension force to the sheet and by means downstream of said station and engageable with said sheet for applying a second tension force to the sheet, each of said upstream means and said downstream means including an arm mounted intermediate its ends for free pivotal movement about a horizontal axis, roller means on one end of the arm for engaging the sheet, and an independently adjustable counterweight on the opposite end of the arm, whereby the difference between the weight of said roller means and the counterweight will define a force exerted on the sheet to provide the respective tension force, the improvement comprising the steps of: applying a first tension force downstream of the station to the sheet with the downstream roller engaging means; applying a second tension force upstream of the station to the sheet with the upstream roller engaging means; monitoring the spacing between said lines printed onto the sheet; adjusting the weight on at least one of the counterweights to thus vary at least one of said tension forces in response to changes in the spacing of said lines to change the speed of the sheet moving past said station and thereby maintain said constant spacing between said lines; and maintaining the varied effective force constant until a change in said constant spacing between said print lines is again monitored.

Claim 6

In a method for substantially instantaneously adjusting the speed of a sheet passing a sheet-handling station to maintain the spacing between adjacent transverse print lines imprinted on the sheet at said station constant over the length of the sheet, the method including the steps of feeding the sheet towards the sheet-handling station; passing the sheet through the sheet-handling station; withdrawing the sheet from the handling station; printing spaced lines on said sheet as it moves through said station, the lines being spaced in a direction transverse to the movement of the sheet; and adjusting the tension applied to the sheet at the upstream and downstream positions of the station, the adjustment of the tension being performed by means upstream of said station and engageable with the sheet for applying a first tension force to the sheet and by means downstream of said station and engageable with said sheet for applying a second tension force to the sheet, each of said upstream means and said downstream means including an arm mounted intermediate its ends for free pivotal movement about a horizontal axis, roller means on one end of the arm for engaging the sheet, and an independently adjustable counterweight on the opposite end of the arm, whereby the difference between the weight of said roller means and the counterweight will define a force exerted on the sheet to provide the respective tension force, the improvement comprising the steps of: applying a first tension force downstream of the station to the sheet with the downstream roller engaging means; applying a second tension force upstream of the station to the sheet with the upstream roller engaging means; monitoring the spacing between said lines printed onto the sheet; adjusting the weight on at least one of the counterweights to thus vary at least one of said tension forces in response to changes in the spacing of said lines to change the speed of the sheet moving past said station and thereby maintain said constant spacing between said lines; and maintaining the varied effective force constant until a change in said constant spacing between said print lines is again monitored.