Feeding sheets of corrugated paperboard

A sheet feeding apparatus, comprising:

• a stack support surface for supporting a stack of sheets;
• a gate adjacent the stack support surface to control one sheet at a time being fed from the stack;
• a plurality of sheet feeding members for feeding an end sheet from the stack past the gate in a downstream direction;
• transfer conveyor means downstream of the gate for continuing feed of the sheet being fed by the sheet feeding members;
• said transfer conveyor means comprising an endless transfer belt, means for driving said transfer belt at a constant speed, and at least first and second vacuum boxes disposed successively along the transfer belt for drawing the sheet being fed against the transfer belt;
• means for continuously connecting each of said vacuum boxes to a vacuum source while the feeding apparatus is feeding sheets;
• each vacuum box having an open face which has to be completely covered by the sheet being fed before that vacuum box is effective in drawing the sheet against the transfer belt;
• said first vacuum box being upstream from said second vacuum box with a separating partition therebetween, the first vacuum box being at a location downstream of said gate;
• an open faced third vacuum box disposed immediately downstream of the second vacuum box and separated therefrom by a partition;
• and
• means for continuously connecting the third vacuum box to a vacuum source while the feeding apparatus is feeding sheets.

A sheet feeding apparatus, comprising:

• a stack support surface for supporting a stack of sheets;
• intermittently driven feed means for feeding the sheets one at a time from the stack through a control gate in a downstream direction;
• a feed vacuum box associated with said feed means and having an open face communicating with a sheet while being fed by said feed means;
• a source of vacuum continuously connected to said feed vacuum box and continuously effective, in use, at said open face;
• transfer conveyor means, downstream of said control gate, for successively receiving each sheet from the feed means and then feeding each sheet downstream of the feeding apparatus;
• and
• said transfer conveyor means comprising:
• a continuously driven endless belt;
• a first transfer vacuum box having an open face cooperative with an upstream portion of said endless belt;
• a second transfer vacuum box having an open face cooperative with a downstream portion of said endless belt;
• means for separately connecting said first and second transfer vacuum boxes continuously, in use, to a supply of vacuum for providing continuous availability of vacuum at the open faces of said first and second transfer vacuum boxes;
• and
• said upstream portion of said endless belt only being effective to grip the sheet being fed while this sheet is completely covering the open face of said first transfer vacuum box, and said downstream portion of said endless belt only being effective to grip the sheet being fed while this sheet is completely covering the open face of said second transfer vacuum box.

Sheet feeding apparatus, comprising:

• a stack support surface for supporting a stack of sheets;
• at least one sheet feeding member for feeding an end sheet from the stack in a downstream direction;
• lift means for moving said sheet feeding member and said stack support surface vertically relative to each other to provide an operative position of said sheet feeding member and an inoperative position thereof;
• an endless belt vacuum conveyor, downstream of said stack support surface, for receiving said end sheet from said sheet feeding member and feeding this sheet further downstream, said vacuum conveyor having at least two open-faced vacuum boxes disposed in series in a downstream direction;
• control means, capable of having information input thereinto, for controlling operation of said lift means including changing from said operative position to said inoperative position in dependence upon a length dimension of the sheets in the downstream direction being input into said control means;
• and
• said control means retaining said operative position until said two vacuum boxes are covered by the sheet being fed.

Sheet feeding apparatus, comprising:

• a stack support surface for supporting a stack of sheets;
• at least one sheet feeding member for feeding an end sheet from the stack in a downstream direction;
• lift means for moving said sheet feeding member and said stack support surface vertically relative to each other to provide an operative position of said sheet feeding member and an inoperative position thereof;
• transfer means, downstream of said stack support surface, for receiving said end sheet from said sheet feeding member and feeding this sheet further downstream;
• control means, capable of having information input thereinto, for controlling operation of said lift means including changing from said operative position to said inoperative position in dependence upon a linear dimension input into said control means and related to the sheets being fed;
• wherein said control means includes a register for input of said linear dimension;
• wherein said lift means includes a servo motor, said register produces a signal in dependence on the input linear dimension, and said signal is employed in controlling the servo motor;
• and
• wherein said control means includes a signal conditioning unit which receives said signal, a machine speed transducer which provides a further signal to the signal conditioning unit in dependence upon a rate at which the sheets are to be fed, said signal conditioning unit producing an output signal which is a function of the signals from said register and said transducer, and said output signal controls the servo motor.

Sheet feeding apparatus, comprising:

• a stack support surface for supporting a stack of sheets;
• at least one sheet feeding member for feeding an end sheet from the stack in a downstream direction;
• lift means for moving said sheet feeding member and said stack support surface vertically relative to each other to provide an operative position of said sheet feeding member and an inoperative position thereof;
• transfer means, downstream of said stack support surface, for receiving said end sheet from said sheet feeding member and feeding this sheet further downstream;
• control means, capable of having information input thereinto, for controlling operation of said lift means including changing from said operative position to said inoperative position in dependence upon a linear dimension input into said control means and related to the sheets being fed;
• and
• wherein said transfer means comprises an endless belt vacuum conveyor having a plurality of open-faced vacuum boxes disposed in series in a downstream direction, said linear dimension is the length dimension of the sheets in said downstream direction, and said control means retains said operative position until all said vacuum boxes are covered by the sheet being fed.