Material handling machine and method

Abstract

The present invention is directed to a machine and method for moving and cutting a continuous web of material. In a preferred embodiment, the machine is a high speed snack bag handling machine operable to move and cut individual filled bags from a continuous web of filled and connected snack bags. Web movement through the machine is achieved by a hand-over-hand movement of a pair of bag grippers which each further include an extendable cutting blade to cut and separate individual bags from the web.

What is claimed is: 
     
         1 . A high speed material handling machine comprising:
 a) first and second parallel, spaced guide rails;   b) first and second gripper assemblies mounted to a respective guide rail in laterally spaced relation with one another, each gripper assembly including:
 i) first and second gripper arms pivotally mounted to a bracket between an open and a closed position, each gripper arm including an upper arm segment and lower arm segment with the lower arm segment having a gripper jaw which extends substantially perpendicular to its respective gripper arm and includes a gripper jaw surface adapted to capture material therebetween when in the closed position; 
 ii) a linkage mechanism interconnected to the upper arm segments through first and second linkages which are pivotally connected to each other wherein each linkage includes respective first and second linkage components adapted to translate relative to one another and are biased toward one another by a biasing member; wherein the first and second linkages are in an angled position when the gripper arms are in the open position and are substantially coplanar to one another when the gripper arms are in the closed position; 
 iii) a linkage control mechanism to control movement of the linkage mechanism between the angled and substantially coplanar positions, the linkage control mechanism including:
 a) a trigger rod connected to and extending between the linkages, the trigger rod having a head with a central bore; 
 b) a cylinder and piston assembly including a piston rod extending coaxially with the trigger rod wherein the piston rod is linearly spaced from the trigger rod when in an extended position and wherein the piston rod impacts the central bore of the trigger rod when in the compressed position thereby engaging the trigger rod to cause the linkages to pivot to the coplanar position; and 
 
   c) a drive mechanism to alternately raise and lower the gripper arm assemblies in a synchronized fashion wherein the first and second gripper assemblies alternate between a respective raised and lowered position,   wherein as one of the gripper assemblies moves from the lowered position to the raised position along its respective guide rail, the gripper jaws thereof are in the open position and not engaging the material such that the material is free to travel in between the open gripper jaws, and wherein when the one of the gripper assemblies is open and being raised, the gripper jaws of the other of the gripper assemblies are closed and being lowered thereby carrying the captured material such that it passes between the spacing of the open gripper jaws as the gripper assemblies pass each other.   
     
     
         2 . The high speed material handling machine of  claim 1  wherein at least one gripper assembly has gripper jaws equipped with a cutter. 
     
     
         3 . The high speed material handling machine of  claim 2  wherein the gripper assembly bracket of the gripper assembly carrying the gripper jaws equipped with the cutter includes a cam block having a pair of spaced flanges which taper gradually toward one another such that cam rollers situated on the gripper jaws engage the cam block between the spaced flanges thereby causing the gripper jaws to be increasingly directed toward one another such that the material captured between the gripper jaws is cut with the cutter. 
     
     
         4 . The high speed material handling machine of  claim 1  further comprising a piston stop mounted onto each respective rail wherein each respective piston rod impacts upon its respective piston stop thereby causing the piston rod to engage the trigger rod to pivot the linkages to the coplanar position. 
     
     
         5 . The high speed material handling machine of  claim 4  wherein the piston stop is adjustable. 
     
     
         6 . The high speed material handling machine of  claim 1  wherein the drive mechanism is a linear actuator. 
     
     
         7 . The high speed material handling machine of  claim 1  wherein the drive mechanism is a cam arm drive mechanism, the cam arm drive mechanism comprising a crank rod having a first end and a second end, wherein the first end is pivotally connected to a crank arm at a pivot point which passes through a selected one of a plurality of linearly spaced through holes formed in the crank arm and wherein the second end is pivotally mounted to a respective gripper assembly via a stop plate; and wherein the crank arm has a first end and a second end wherein the first end is attached to a rotating sprocket gear such that the pivot point is located between the rotating sprocket gear and the second end of the crank arm, and wherein the rotating sprocket gear is driven by a drive sprocket gear through a connecting looped belt. 
     
     
         8 . The high speed material handling machine of  claim 7  wherein the cam arm drive mechanism further comprises an eccentric stop adapted to receive command signals from a sensor so as to rotate the eccentric stop thereby adjusting a stroke length of said cam arm drive mechanism. 
     
     
         9 . The high speed material handling machine of  claim 7  wherein the crank arms are 180° out of phase.