Intermittently protruding feeder for paperboard blanks

Apparatus for feeding corrugated blanks one by one from the bottom of a stack of blanks without slippage and so that the leading edge of the blank being fed always enters the nip of nip rolls at the same point in the machine cycle with precision suitable for printing and slotting, said apparatus comprising

• a. nip rolls adapted to be operated with a surface velocity;
• b. stack supporting structure including a forward portion, and gate means positioned above the stack supporting structure to define an opening which is upstream of the nip rolls;
• c. transport means supported under said forward portion of said stack supporting structure, said transport means comprising continuous high coefficient of friction surface adapted to be circulated to feed the lowermost blank through said opening just to said nip rolls;
• d. reciprocating means for changing the relative vertical relationship of said high coefficient of friction surface and said forward portion of said stack supporting structure so as to alternately provide an active position where said high coefficient of friction surface extends above the top of said stack supporting structure forward portion and a passive position where said high coefficient of friction surface does not extend above the top of said stack supporting structure forward portion;
• e. suction means for urging a blank downwardly into surface-to-surface static friction engagement with protruding continuous high coefficient of friction surface when the latter is in the active position;
• f. transmission means comprising input shaft means which is adapted to be rotated and output shaft means which is adapted to be rotated, said input and output shaft means being operatively connected so that the output shaft means undergoes controlled acceleration during an initial period of each revolution of said input shaft means once said friction surface is stationary and in said active position with a blank resting on transport means friction surface and is stationary during a last portion of each revolution of said input shaft means;
• g. means operatively connecting the output shaft means of the transmission means and the transport means so that during the operation of the apparatus said high coefficient of friction surface is circulated and undergoes controlled acceleration only after a blank is resting thereon followed by net deceleration only after the nip rolls receive the blank followed by a dwell period during which said high coefficient of friction surface is stationary;
• h. the apparatus being such that the active position is effected to bring the non-circulating continuous high coefficient of friction surface into engagement with the lowermost blank directly before said high coefficient of friction surface undergoes controlled acceleration, and the passive position is effected to disengage the high coefficient of friction surface and the blank at the conclusion of the controlled acceleration once the nip rolls have received the blank;
• i. the elements (c), (f) and (g) being such that a blank being fed is accelerated to enter the nip rolls at the same velocity as the surface velocity of the nip rolls;
• whereby high coefficient of friction surface of said transport means engages and grips the lowermost blank by static friction and alone moves and accelerates that blank to the nip rolls without slippage occurring and so that each blank enters the nip rolls in register whereupon the blank is disengaged from the transport means.