Pack alignment apparatus and methods using linear motor

Abstract

A system for forming and wrapping a plurality of stacks of sheet-like product is provided. The system includes a stack aligner for squaring up leading and trailing ends of the stack as well as sides of the stacks is provided. The stack aligner is also configured for controlling the position of the stacks along the stack travel path such that the stacks exit the stack aligner with tight positional tolerances for being fed to the stack wrapping arrangement.

1 . A method of aligning a stack of a plurality of vertically stacked sheet-like products as the stack travels along a travel path as the stack travels through a stack aligner along the travel path, the stack having a downstream leading end, an upstream trailing end, a pair of sides extending between the leading end and the trailing end, a top and a bottom, the method comprising:
 feeding the stack to the stack aligner,   pressing the stack between a first paddle of the stack aligner that is downstream from the stack and a second paddle of the stack aligner that is upstream from the stack so as to substantially align all of the sheet-like product such that the leading end and trailing end of the stack are substantially parallel to one another and orthogonal to the travel path.   
     
     
         2 . (canceled) 
     
     
         3 . The method of  claim 1 , further comprising squeezing the stack in a transverse direction that is perpendicular to the travel path so as to substantially align substantially all of the sheet-like product such that the sides of the stack are substantially parallel to one another and orthogonal to the leading and trailing ends. 
     
     
         4 . (canceled) 
     
     
         5 . The method of  claim 3 , wherein the step of squeezing the stack in a transverse direction is performed by passing the stack between a pair of transversely offset side guides that extend parallel to one another and parallel to the travel path; and
 wherein the stack is pushed between the side guides by the second paddle.   
     
     
         6 . The method of  claim 1 , further comprising independently controlling the position of the first and second paddles along the travel path. 
     
     
         7 . (canceled) 
     
     
         8 . The method of  claim 7 , The method of  claim 6  further comprising dispensing the stacks from the stack aligner; and
 wherein the stacks are fed to the stack aligner at a first speed along the travel path and are dispensed from the stack aligner at a second speed along the travel path, different than the first speed. 
 
     
     
         9 . A method of aligning stacks of a stream of stacks as the stacks travel through a stack aligner as the stacks travel along a stack travel path, each stack including a plurality of stacked sheet-like products, each stack generally having a downstream leading end, an upstream trailing end, a pair of sides extending between the leading end and the trailing end, a top and a bottom, the method comprising:
 feeding the stream of stacks to the stack aligner with a gap formed between adjacent stacks,   inserting a paddle of the stack aligner into each gap between adjacent stacks, such that each stack has a paddle upstream of the stack and a paddle downstream from the stack; and   pressing each stack between the paddle upstream of the stack and the paddle downstream of the stack so as to substantially align all of the sheet-like product such that the leading end and trailing end of the stack are substantially parallel to one another and orthogonal to the stack travel path.   
     
     
         10 . The method of  claim 9 , further comprising changing the spacing between the paddle upstream of the stack and the paddle downstream of the stack such that the paddle downstream of the stack no longer contacts the stack and the stack is pushed by the paddle upstream of the stack. 
     
     
         11 - 13 . (canceled) 
     
     
         14 . The method of  claim 9 , further comprising independently controlling the position of the first and second paddles along the stack travel path. 
     
     
         15 . (canceled) 
     
     
         16 . The method of  claim 9 , further comprising increasing a number of accumulated stacks within the stack aligner:
 wherein increasing a number of accumulated stacks within the stack aligner includes:
 feeding the stream of stacks to the stack aligner with a gap formed between adjacent stacks at an average feed rate but with an inconsistent gap width between adjacent stacks; and 
 dispensing the stacks at an outlet end of the stack aligner at an average dispensing rate with a substantially equal spacing between adjacent stacks, the supply rate being greater than the dispensing rate. 
   
     
     
         17 - 20 . (canceled) 
     
     
         21 . The method of  claim 9 , wherein each paddle remains in a substantially orthogonal orientation relative to the stack travel path as the paddle is inserted into a corresponding gap between adjacent stacks. 
     
     
         22 . The method of  claim 21  further including retracting each paddle from the corresponding gap between each adjacent stack and wherein each paddle remains in a substantially orthogonal orientation relative to the stack travel path as the paddle is retraced from the corresponding gap between adjacent stacks. 
     
     
         23 . A method of transporting stacks of a stream of stacks from a log saw where the stacks are formed from a plurality of longer logs to a wrapper for wrapping the stacks, each stack including a plurality of stacked sheet-like products, each stack generally having a downstream leading end, an upstream trailing end, a pair of sides extending between the leading end and the trailing end, a top and a bottom, the method comprising
 feeding the stacks to a stack aligner as the stacks travel along a stack travel path at a stack aligner inlet;   dispensing the stacks from the stack aligner at a stack aligner outlet;   sensing a position of each stack prior to feeding the stack to the stack aligner;   calculating a motion profile to insert a paddle of the stack aligner after each stack.   
     
     
         24 . The method of  claim 23 , further comprising
 receiving the stacks at an inlet end of the stack aligner at an average supply rate but with unequal spacing between adjacent stacks; and   dispensing the stacks at an outlet end of the stack aligner at an average dispensing rate with a substantially equal spacing between adjacent stacks.   
     
     
         25 - 26 . (canceled) 
     
     
         27 . A stack aligner for aligning stacks of a stream of stacks as the stacks travel along a stack travel path, adjacent ones of the stacks being longitudinally spaced apart along the stack travel path forming a gap therebetween, each stack including a plurality of stacked sheet-like products, each stack generally having a downstream leading end, an upstream trailing end, and a pair of sides extending between the leading end and the trailing end, the stack aligner comprising:
 a plurality of paddles configured for being inserted into the gap between adjacent stacks;   a guide arrangement for guiding the paddles along a paddle travel path, the paddle travel path having a portion thereof that is coincident with a portion of the stack travel path;   a control arrangement configured to independently control the motion of the paddles along the paddle travel path.   
     
     
         28 . The stack aligner of  claim 27 , wherein the control arrangement is configured to control the motion of the of the plurality of paddles such that when adjacent paddles have been inserted into corresponding gaps, the control arrangement reduces the spacing between adjacent paddles such that the paddles press the stack positioned therebetween between the paddle upstream of the stack and the paddle downstream of the stack so as to substantially align all of the sheet-like product such that the leading end and trailing end of the stack are substantially parallel to one another and orthogonal to the stack travel path. 
     
     
         29 - 30 . (canceled) 
     
     
         31 . The stack aligner of  claim 27 , wherein:
 the guide arrangement includes:
 a carriage track that defines a closed guide path; 
 a first cam track; 
 a second cam track; 
   each paddle is pivotally attached to a guide carriage that is guided by the carriage track along the closed guide path,   each paddle is operably coupled to first and second cam followers;   the first cam follower and the first cam track are configured to rotate the paddle relative to the guide carriage at least 75 degrees; and   the second cam follower and the second cam track are configured to rotate the paddle relative to the guide carriage at least 75 degrees.   
     
     
         32 . The stack aligner of  claim 27 , wherein:
 the guide arrangement includes:
 a carriage track that defines a closed guide path; 
 a cam track arrangement; 
   each paddle is pivotally attached to a guide carriage that is guided by the carriage track along the closed guide path for motion in a single direction,   each paddle is operably attached to a cam follower arrangement;   the cam track arrangement and cam follower arrangement are configured to rotate the paddle relative to the carriage track and the closed guide path while inserting the paddle between adjacent stacks; and   the cam track arrangement and cam follower arrangement are configured to rotate the paddle relative to the carriage track and the closed guide path while removing the paddle from between adjacent stacks.   
     
     
         33 . The stack aligner of  claim 32 , wherein:
 the cam track arrangement and cam follower arrangement are configured to rotate the paddle relative to the corresponding guide carriage in a first angular direction while inserting the paddle between adjacent stacks; and   the cam track arrangement and cam follower arrangement are configured to rotate the paddle relative to the corresponding guide carriage in the first angular direction while removing the paddle from between adjacent stacks.   
     
     
         34 . The stack aligner of  claim 33 , wherein the cam track arrangement and cam follower arrangement are configured to rotate the paddle relative to the corresponding guide carriage in a second angular direction after the paddle has been removed from between adjacent stacks to prepare the paddle to be inserted into another gap between another pair of adjacent stacks. 
     
     
         35 . The stack aligner of  claim 32 , wherein:
 the cam track arrangement and cam follower arrangement are configured to rotate the paddle relative to the carriage track and the closed guide path such that the paddle remains substantially orthogonal to the stack travel path as the paddle is inserted into the gap; and   the cam track arrangement and cam follower arrangement are configured to rotate the paddle relative to the carriage track and the closed guide path such that the paddle remains substantially orthogonal to the stack travel path as the paddle is removed from the gap.   
     
     
         36 . (canceled) 
     
     
         37 . The stack aligner of  claim 32 , wherein:
 the first cam follower and the first cam track are configured to maintain upstream and downstream contact surfaces of the paddle in a substantially orthogonal orientation relative to the stack travel path as the paddles are transitioned into a gap between adjacent stacks; and   the second cam follower and the second cam track are configured to maintain the upstream and downstream contact surfaces of the paddle in a substantially orthogonal orientation relative to the stack travel path as the paddles are transitioned out of the gap between adjacent stacks.   
     
     
         38 . (canceled) 
     
     
         39 . The stack aligner of  claim 27 , wherein the control arrangement is configured to control the motion of the of the plurality of paddles such that after adjacent paddles have pressed a stack positioned therebetween, the longitudinal spacing along the paddle travel path, as well as the stack travel path, between the adjacent paddles is increased so that only the trailing end of the stack is contacted the paddle upstream from the corresponding stack. 
     
     
         40 . The stack aligner of  claim 27 , wherein the control arrangement is configured to independently control the motion of the paddles such that the positional tolerance of each stack along the stack travel path after the stack is no longer controlled by a paddle of the stack aligner is less than 0.25 inches. 
     
     
         41 . The stack aligner of  claim 27 , wherein the motion of the paddles is not mechanically tied to one another such that each paddle can be independently accelerated along the paddle travel path. 
     
     
         42 . The stack aligner of  claim 27 , further comprising an in feed conveyor; an out feed conveyor and a low friction surface interposed between the in feed conveyor and the out feed conveyor.