Material handling apparatus for printing plastic film

In apparatus for printing on extensible flexible sheet material including a plurality of printing cylinders, a continuous elongated support web for said material passing sequentially under said rolls, a plurality of web rolls with cylindrical surfaces in contact with said web, means for driving at least one of said web rolls and thereby driving said web, a supply roll and a takeup roll for said sheet material, the improvement of flexible sheet supply and takeoff apparatus comprising,

• a contact roll supported on pivot arms adjacent said supply roll for movement in an arc intercepting the surface of a supply roll of sheet material at both the full and near empty conditions of said roll, said contact roll having a cylindrical surface with a substantial coefficient of friction relative to said sheet material,
• means for rotating said contract roll at a speed causing its surface velocity to be a constant factor of from 1% to 10% less than the surface velocity of said support web, said means including a rim integral with said roll of slightly larger diameter than said cylindrical surface and in frictional engagement with the surface of said one of said web rolls,
• a second contact roll supported on arms adjacent said takeup roll for movement on a path intercepting the surface of a takeup roll of sheet material at both the full and near empty conditions of said roll, said second contact roll having a cylindrical surface with a substantial coefficient of friction relative to said sheet material, and
• means for rotating said second contact roll at a speed causing its surface speed to be a constant factor of from 1% to 10% greater than the velocity of said support web.

In apparatus for printing on extensible flexible sheet material including a plurality of printing cylinders, a continuous elongated support web for said material passing sequentially under said rolls, a plurality of web rolls with cylindrical surfaces in contact with said web, means for driving at least one of said web rolls and thereby driving said web, a supply roll and a takeup roll for said sheet material, the improvement of flexible sheet supply and takeoff apparatus comprising,

• a contact roll supported on pivot arms adjacent said supply roll for movement in an arc intercepting the surface of a supply roll of sheet material at both the full and near empty conditions of said roll, said contact roll having a cylindrical surface with a substantial coefficient of friction relative to said sheet material,
• means for rotating said contract roll at a speed causing its surface velocity to be a constant factor of from 1% to 10% less than the surface velocity of said support web, said means including a rim integral with said roll of slightly larger diameter than said cylindrical surface and in frictional engagement with the surface of said one of said web rolls,
• a second contact roll supported on pivot arms adjacent said takeup roll for movement in an arc intercepting the surface of a takeup roll of sheet material at both the full and near empty conditions of said roll, said second contact roll having a cylindrical surface with a substantial coefficient of friction relative to said sheet material, and
• means for rotating said second contact roll at a speed causing its surface speed to be a constant factor of from 1% to 10% greater than the velocity of said support web, said means including a drive element with a rotational speed proportional to said web speed and concentric with the pivotal axis of said second pivot arms, and a driven element concentric with the axis of said second contact roll and rotationally engaged thereto.

In apparatus for printing on extensible flexibel sheet material including a plurality of printing cylinders, a continuous elongated support web for said material passing sequentially under said rolls, a plurality of web rolls with cylindrical surfaces in contact with said web, means for driving at least one of said web rolls and thereby driving said web, a supply roll and a takeup roll for said sheet material, the improvement of flexible sheet supply and takeoff apparatus comprising,

• a contact roll supported on pivot arms adjacent said supply roll for movement in an arc intercepting the surface of a supply roll of sheet material at both the full and near empty conditions of said roll, said contact roll having a cylindrical surface with a substantial coefficient of friction relative to said sheet material,
• means for rotating said contact roll at a speed causing its surface velocity to be about 2.5% less than the surface velocity of said support web, said means including a rim integral with said roll of slightly larger diameter than said cylindrical surface and in frictional engagement with the surface of said one of said web rolls.
• a second contact roll supported on second pivot arm adjacent said takeup roll for movement in an arc intercepting the surface of a takeup roll of sheet material at both the full and near empty conditions of said roll, said second contact roll having a cylindrical surface with a substantial coefficient of friction relative to said sheet material, and
• means for rotating said second contact roll at a speed causing its surface speed to be about 3% greater than the velocity of said support web, said means including a drive element with a rotational speed proportional to said web speed and concentric with the pivotal axis of said second pivot arms, and a driven element concentric with the axis of said second contact roll and rotationally engaged thereto.