US 4,358,100 AGranted

Apparatus for singularizing stacked sheets

AssigneeGrapha-Holding AG

InventorHans Muller

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Abstract

A cylindrical drum of a rotary transfer conveyor rotates below an opening at the bottom of a magazine for a stack of superimposed sheets. The drum carries a first pivotable gripping lever and one or more second pivotable gripping levers. The common pivot axis of the levers is parallel to the axis of the drum, and the levers are pivotable by cams so that their speed relative to the magazine is less than the peripheral speed of the drum during travel immediately below the opening in the bottom of the magazine. At such time, a set of suction cups flexes a portion of the lowermost sheet of the stack through the opening and between the first and second gripping levers so that the speed of the engaged sheet need not be immediately accelerated to the peripheral speed of the drum but merely to the relatively low absolute speed of the levers. The levers extract the lowermost sheet from the magazine and simultaneously accelerate the extracted sheet to the peripheral speed of the drum prior to moving apart so that the sheet can descend by gravity. The levers subsequently return to positions below the opening in the bottom of the magazine to proceed with extraction of the next lowermost sheet.

Apparatus for feeding sheets comprising:

(a) a magazine for confining a stack of sheets;
(b) rotary carrier means for transferring sheets from said magazine to a location spaced from the same;
(c) drive means for said carrier means;
(d) first gripping means mounted on said carrier means for rotation therewith and for movement relative thereto;
(e) first moving means for moving said first gripping means relative to said carrier means in response to rotation of the latter such that the speed of said first gripping means relative to said magazine varies between a lower value in the region of said magazine and a higher value remote from said magazine, said first moving means including a stationary first cam, a first shaft coupled to said first gripping means and mounted on said carrier means so as to project from the latter towards said first cam, and a first follower on said shaft tracking said first cam;
(f) second gripping means mounted on said carrier means for rotation therewith and for movement relative thereto, said second gripping means being arranged to cooperate with said first gripping means to grip a sheet during transfer of the same from said magazine to said location;
(g) second moving means for moving said second gripping means relative to said carrier means in response to rotation of the latter such that the speed of said second gripping means relative to said magazine varies between a lower value in the region of said magazine and a higher value remote from said magazine, said second moving means including a stationary second cam, a second shaft coupled to said second gripping means and mounted on said carrier means so as to project from the latter towards said second cam, and a second follower on said second shaft tracking said second cam, said first and second moving means also being arranged to move said first and second gripping means together in the region of said magazine so as to grip a sheet to be transferred and to move said first and second gripping means apart in the region of said location so as to release the sheet;
and
(h) introducing means for introducing sheets from said magazine to said first and second gripping means.

6 more elements

Abstract

Claims15