Apparatus and method for breaking open and aerating sheet material stacks

Abstract

An apparatus and a method for separating and aerating sheet material arranged in a stack include a support to receive the sheet material stack thereon before the same is separated and aerated. A roll mechanism clamps the sheet material stack between an upper rotatable roll and a lower drivable roll. The sheet material stack is conveyed into a position between the upper and lower rolls when the same are in an open position. A ram converges the upper and lower rolls to clamp the sheet material stack therebetween. A drive rotates the lower roll in the conveying direction of the sheet material stack, and a gripper selectively grips the front end of the sheet material stack.

1 . A method for separating and aerating sheets of material arranged in a stack having forward and rearward ends, comprising the steps of:
 positioning the sheet material stack on a first support;   advancing the sheet material stack such that the forward end thereof extends beyond the first support;   positioning a rotatable upper roll above the first support and the sheet material stack;   positioning a drivable lower roll below the first support and the sheet material stack;   gripping the forward end of the sheet material stack in a gripper;   converging the upper roll and the lower roll to clamp therebetween that portion of the sheet material stack disposed adjacent to the gripper at a clamping region, whereby at least a portion of the sheet material stack wraps around a predetermined portion of the circumference of the upper roll at a location forward of the clamping region;   advancing the sheet material stack by driving the lower roll, and simultaneously shifting the gripper to retain the material stack between the gripper and the upper and lower rolls until the rearward end of the sheet material stack passes out of the clamping region, thereby separating and aerating the sheets in the sheet material stack;   further shifting the gripper to position the separated sheets in the sheet material stack on a second support; and   releasing the gripper to ungrip the forward end of the sheet material stack.   
     
     
         2 . A method as set forth in  claim 1 , wherein:
 said upper and lower roll positioning steps include selecting the diameter of the upper roll smaller than the diameter of the lower roll.   
     
     
         3 . A method as set forth in  claim 1 , wherein:
 said advancing step includes positioning the sheet material stack on the first support and advance the same horizontally; and wherein   said converging step includes positioning the first support with respect to the upper roll as a function of the thickness of the sheet material stack to vary the degree of wraparound of the upper roll.   
     
     
         4 . A method as set forth in  claim 3 , wherein:
 said converging step further comprises converging the upper roll and lower roll to a point where the sheet material stack wraps around the upper roll over an angle in the range of 30 to 50 degrees in front of the clamping region.   
     
     
         5 . A method as set forth in  claim 1 , including:
 coordinating the circumferential speed of the upper roll relative to the movement speed of the gripper.   
     
     
         6 . A method as set forth in  claim 5 , including:
 shifting the gripper at a speed which is slightly lower than the circumferential speed of the upper roll.   
     
     
         7 . A method as set forth in  claim 1 , including:
 shifting the material stack substantially horizontally, apart from its deflection in the region of the upper and lower rolls.   
     
     
         8 . A method as set forth in  claim 1 , including:
 blowing air in from the side of the material stack between the individual sheets at the fanned open region of the material stack in front of the lower roll.   
     
     
         9 . An apparatus for separating and aerating sheets of material arranged in a stack, comprising:
 a support shaped to receive thereon a sheet material stack before the same is separated and aerated;   a roll mechanism configured for clamping the sheet material stack between an upper rotatable roll and a lower drivable roll;   a conveyor mechanism converging the sheet material stack into a position between said upper and lower rolls when the same are in an open position;   a ram converging and diverging said upper and lower rolls;   a drive rotating the lower roll in the converging direction of the sheet material stack; and   a gripper selectively gripping a front end of the sheet material stack.   
     
     
         10 . An apparatus as set forth in  claim 9 , wherein:
 said upper roll has an outside diameter that is smaller than the outside diameter of said lower roll.   
     
     
         11 . An apparatus as set forth in  claim 9 , wherein:
 said conveyor mechanism comprises a gripper.   
     
     
         12 . An apparatus as set forth in  claim 9 , wherein:
 said upper roll is mounted such that it can be freely rotated.   
     
     
         13 . An apparatus as set forth in  claim 9 , wherein:
 said drive rotating said lower roll comprises an electric motor.   
     
     
         14 . An apparatus as set forth in  claim 9 , wherein:
 said upper roll includes a hard circumferential face.   
     
     
         15 . An apparatus as set forth in  claim 9 , wherein:
 said lower roll includes a soft circumferential face.   
     
     
         16 . An apparatus as set forth in  claim 9 , wherein:
 said upper and lower rolls are arranged such that a plane passing through the pivot axes of said upper and lower rolls is disposed at an angle in the range of 40 to 50 degrees with respect to the horizontal.   
     
     
         17 . An apparatus as set forth in  claim 9 , including:
 a rotary encoder operably connected with and detecting the rotary angle and/or rotational speed of said upper roll.   
     
     
         18 . An apparatus as set forth in  claim 17 , including:
 a controller operably connected with said rotary encoder and including a drive for moving said gripper.