Method and device for feeding sheets one by one from a pile of sheets
AssigneeBerg Industries Aktiebolag
InventorHans Levin
Life of this patent
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Abstract
A method and device for feeding sheets one by one from a stack of sheets to a transportation device are described. The sheet-feeding device comprises a number of parallel, separately driven shafts which are equidistantly spaced from one another and are enclosed in a low-pressure chamber and carry a plurality of feeding wheels. A separating device is arranged above the low-pressure chamber. At least one relieving element is arranged in a vertically displaceable manner between a sheet-supporting position and a non sheet supporting position. Each relieving element is positioned before each wheel shaft and the movement thereof as well as the rotational movement of the wheels are controlled by the control unit depending on the position of the rear edge of the sheet relatively to the wheels.
Claims21
A device for feeding sheets one by one from a stack of sheets to a transportation device for transporting the sheet to a process station, comprising:
- a first low-pressure chamber,
- a number of separately driven shafts which are positioned perpendicular to the direction of transportation of the sheets, which are arranged in the low-pressure chamber essentially equi-distantly spaced from one another, and which each carry a plurality of wheels with friction lining, each shaft being driven by its own motor which is connected to and controlled by a control unit,
- a separating device which is arranged essentially vertically above the low-pressure chamber and at a distance from the low-pressure chamber that is somewhat larger than the thickness of a sheet, and
- at least one relieving element arranged in a vertically displaceable manner before and at a distance from the closest shaft relative to the direction of transportation of the sheets and which is connected to and controlled by said control unit
- wherein said control unit is arranged to control the relieving element such that the relieving element is raised to a supporting position for the second lowermost sheet of the stack of sheets, essentially at the same time as a rear edge of a lowermost sheet being fed, relative to the direction of transportation of the lowermost sheet, is moved past said relieving element.
A method for feeding sheets one by one from a stack of sheets in a feeding device to a transportation device for transporting the sheet to a process station, the feeding device comprising
- a low-pressure chamber,
- a number of separately driven shafts which are positioned perpendicular to the direction of transportation and are arranged in the low-pressure chamber essentially equidistantly spaced from one another and which each carry a plurality of wheels with friction lining, each shaft being driven by its own drive motor, which is connected to and controlled by a control unit, and
- a separating device, which is arranged essentially vertically above the low-pressure chamber and at a distance from the low-pressure chamber that is somewhat larger than the thickness of a sheet, the method comprising:
- feeding a lowermost sheet in the stack to the transportation device, while preventing a second lowermost sheet from moving by means of the separating device,
- accelerating the sheet by causing the wheels, which are immobile at the beginning of each feeding cycle, to rotate by means of the control unit connected to the drive motors of the wheels and to said process station, so that the sheet reaches its speed reference value depending on the working pace of the process station,
- raising a relieving element essentially at the same time as a rear edge of the lowermost sheet being fed, relative to the direction of transportation of the lowermost sheet, is moved past said relieving element, to a supporting position for the second lowermost sheet of the stack of sheets before the lowermost sheet being fed leaves a subsequent shaft, relative to the direction of transportation of the lowermost sheet, which carries wheels, and
- decelerating said subsequent shaft when the rear edge of the lowermost sheet being fed, as seen in the direction of transportation, leaves the wheels of the subsequent shaft.
Dependencies are inferred from the claim text.