Abstract:
A stitching head is provided having a cam connected to the bender rail rail, the cam operates to redirect the staple driving force being applied by the driver rail to the driver and upon the staple during the staple driving step of stitching head operation; the force-redirecting position of the cam is automatically adjusted in response to the thickness of each workpiece as the cam is connected to the bender rail rail and the contacting of the workpiece by the bender rail repositions the cam at the desired distance above the workpiece to reestablish the set-point for the redirection of the staple driving force being applied to the driver rail upon as staple head contacts each variable thickness workpiece.

Description:
CROSS-REFERENCE TO PRIOR APPLICATIONS 
     This application claims priority to U.S. provisional patent application Ser. No. 61/374,906 filed Aug. 18, 2010 titled Stitching Head. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to the area of high speed commercial stitching heads used to insert staples into printed material. More particularly, the present apparatus provides a stitching head which automatically adjusts the amount travel applied to the staple driver by the driver rail of the stitching head in response to the thickness of the workpiece presented to the stitching head. 
     BACKGROUND OF THE INVENTION 
     It is typical of prior art stitching machines that they require mechanical adjustments to the stitching machine&#39;s stitching head actuating or adjustment to the position of the clincher mechanism to accommodate variations in thickness of the workpiece to be stapled. Therefore it would be advantageous if a stitching head could automatically accommodate variations in workpiece thickness without the need for mechanical adjustment of the stitching head actuating bar or clincher mechanism to the stroke distance of the force-providing machine rail. 
     The cam system and interlock system of the stitching head provided herein accomplishes the accommodation of variable thicknesses of workpieces to be stapled by the stitching head without the need for springs or dampeners. It also will be appreciated that the cam system provided herein maintains consistent workpiece closure—the stapling tightness or compression together of the workpiece material or paper stack that is stapled together—without the use of springs or dampeners. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Preferred embodiments of the invention, illustrative of the best modes in which the applicant has contemplated applying the principles, are set forth in the following description and are shown in the drawings and are particularly and distinctly pointed out and set forth in the appended claims. 
         FIG. 1  is a front and left side perspective view of an embodiment showing the cam  16  connected to the bender rail  14  and the transition roller  18  of the cam follower  36  connected between the staple driver or driver  20  and the driver rail  22  and showing the cam follower transition roller  18  positioned in the top most position of the cam  16  path for the beginning of the staple driving step of the staple insertion sequence. 
         FIG. 2  is a front and right side perspective view of the embodiment of  FIG. 1  showing cam follower transition roller  18  approximately at the end of the path of travel along the force-applying leg  32  of the cam  16  and showing the cam follower transition roller  18  approaching the transition to the force-redirecting leg  34  of cam  16 , at the position shown in  FIG. 2  staple-insertion force is being communicated to the driver  20  from the driver rail  22  via the cam follower  36  and the driver  20  is shown nearer to the end of the bender rail  14 . 
         FIG. 3  is a front and right side perspective view of the embodiment of  FIG. 1  showing the cam follower transition roller  18  at the end of its travel along the force-applying leg  32  of cam  16  after it has passed from the force-applying leg  32  of the cam  16  and entered the force-redirecting leg  34  of cam  16  wherein the force communicated from the driver rail  22  is redirected into causing the movement of cam follower transition roller  18  of cam follower  36  along the force-redirecting leg  34  of cam  16  thereby ending the communication of staple-insertion force from driver rail  22  to driver  20  as the driver has reached the end of the bender rail  14 . 
         FIG. 4  is a cross-section view taken along line  4 - 4  of  FIG. 1  and showing the cam follower transition roller  18  of cam follower  36  at the top of force-applying leg  32  of cam  16  and which position is immediately prior to the downward movement of cam follower transition roller  18  resulting from the driver rail  22  starting downward movement to move the driver  20  downwardly for insertion of a staple  7 . 
         FIG. 5  is a front elevation view of a another stitching head embodiment for preventing the delivery of excess drive rail force to the driver and showing the first flange  84  and the second flange  92  both in the locked position. 
         FIG. 6  is a front elevation view of the stitching head of  FIG. 5  and showing the first flange  84  in the unlocked position and the second flange  92  in the locked position. 
         FIG. 7  is a front elevation view of the stitching head of  FIG. 5  and showing the first flange  84  and the second flange  92  both in the unlocked position. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As required, detailed embodiments of the present inventions are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. 
     Referring now to  FIG. 1 , a front and left side view of the bender rail and driver components of a stitching head  10  is shown. A frame piece  12  is provided having a bender rail  14  movably connected thereto. Bender rail  14  is provided with a cam  16  which is connected to bender rail  14 . Cam  16 , as more completely identified hereinafter, is comprised of a first leg  32  which is a force-applying leg and a second leg  34  which is a force-redirecting leg. The operation and effect of these two cam legs  32 ,  34  will be further described hereinafter. A cam follower  36  is provided which travels the path of cam  16 . The construction and operation of cam follower  36  will be further described hereinafter. 
     Still referring to  FIG. 1 , driver  20  is connected to bender rail  14  and driver  20  slidably moves within tracks  6  on either side of bender rail  14 . During operation, a staple  7  is disposed directly below driver  20 . Staple  7  also rides in tracks  6 . Driver  20  is connected to driver rail  22  by cam follower  36 . Referring to  FIG. 4 , cam follower  36  is comprised of several components that connect driver rail  22  to driver  20 . More particularly, cam follower  36  is comprised of a cam follower upper link  26  which is pivotally connected to driver rail  22  by cam follower upper roller  24 . Cam follower  36  also has a lower link  30  which is connected to driver  20  by cam follower lower roller  28 . Upper link  26  and lower link  30  of cam follower  36  are pivotally connected by cam follower transition roller  18  which extends into cam  16  such that the movement of upper link  26  and lower link  30  comprising cam follower  36  is directed by the pathway formed by cam  16 . It is cam follower transition roller  18  which travels along the path presented by cam  16  ( FIG. 1 ). As will be described hereinafter, the position of cam follower  36  as determined by the position of transition roller  18  within cam  16  determines the amount of force that is communicated from driver rail  22  through cam follower  36  and to driver  20 . This variation in the application of force will be further described hereinafter with reference to  FIGS. 1-4 . 
     Referring now to  FIGS. 1-4 , the application of force to achieve the insertion of a staple  7  into a work piece  5  ( FIG. 1 ) will be described. First referring to  FIG. 1 , bender rail  14  is shown extended from frame  12  and in position to contact and compress a work piece  5  prefatory to the insertion of a staple  7  into the work piece  5  by driver  20 . Also shown in  FIG. 1 , driver  20  is in its uppermost position as limited by transition roller  18  of cam follower  36  ( FIG. 4 ) within force-applying leg  32  of cam  16 . It will be appreciated that cam  16  is connected to bender rail  14 , therefore, the position of cam  16  with respect to frame  12  is determined by the thickness of the work piece  5  which bender rail  14  contacts. It also will be appreciated that as the thickness of work piece  5  increases the vertical distance traveled by driver  20  within bender rail  14  decreases and as a work piece  5  becomes thinner, bender rail  14  is further downwardly extended with respect to frame  12  and the distance traveled by driver  20  becomes greater. This variation in the distance traveled by driver  20  with respect to bender rail  14  as being dependent upon the thickness of a work piece  5  will become clear as the operation of stitch head  10  is further described. 
     Again referring to  FIG. 1 , transition roller  18  of cam follower  36  is shown in the uppermost position permitted by cam  16  and which is the position of transition roller  18  and driver  20  just prior to the initiation of a downward stroke for insertion of a staple by stitch head  10 . In operation transition roller  18  then moves downwardly from the position shown in  FIG. 1 . This movement is in response to the downward movement of driver rail  22 , the movement of which is governed by the actuating bar (not shown) of the stitching machine (not shown) into which stitch head  10  has been inserted. The downward movement of driver rail  22  is communicated through cam follower  36  and to driver  20  which begins the forcing of a staple  7  into work piece  5 . It will be appreciated that the orientation of force-applying leg  32  provides a generally straight-line connection between driver rail  22  and driver  20  thereby communicating the entire force applied to driver rail  22  to driver  20  for the insertion of a staple into a work piece  5 . It also will be appreciated by comparing the position of driver  20  in  FIG. 1  to the position of driver  20  shown in  FIG. 2  that downward movement of driver  20  has been generated as a result of the downward movement of driver rail  22  communicated through transition roller  18  and cam follower  36  as governed by the pathway of cam  16 . 
     Referring now to  FIG. 2 , transition roller  18  of cam follower  36  is in the transition area at which the path established by cam  16  changes from a force-applying leg  32  into a force-redirecting path established by force-redirecting leg  34  of cam  16 . It will be appreciated by a comparison of the position of driver  20  in  FIG. 2  with the position shown in  FIG. 1  that downward progress of driver  20  has occurred as transition roller has been further moved along force-applying leg  32  of cam  16  by driver rail  22 . 
     As transition roller  18  enters the initial portion of force-redirecting leg  34  of cam  16  and driver  20  is shown nearly to the end of bender rail  14  at which point the crown (the portion that connects the two legs of the staple) of staple  7  would be in contact with the work piece  5 . With the staple crown in contact with the work piece, further downward driving of the staple  7  into the work piece  5  can be terminated. As transition roller  18  moves further along force-redirecting leg  34  of cam  16  the position of driver  20  becomes even with the end of bender rail  14 . It is at this position of driver  20  that the crown of a staple  7  would be pressed against work piece  5  and the termination of downward force by driver  20  against the staple crown should occur. Terminating additional downward force will avoid pressing the staple crown into the work piece and/or through the work piece  5  thereby causing damage to the work piece and a stitching failure. To avoid further downward pressure against the staple by driver  20  the force being applied by driver rail  22  either must be terminated or redirected to avoid the further application of force to a staple being inserted by driver  20 . This redirection of force is accomplished by further movement of cam follower  36  along force-redirecting leg  34  of cam  16  as shown in  FIG. 3 . In the end position of force-redirecting leg  34  no further downward movement of driver  20  occurs even though additional downward movement of driver rail  22  occurs and transition roller  18  travels farther along force-redirecting leg  34  of cam  16 . 
     It is the movement of cam follower transition roller  18  along force-redirecting leg  34  of cam  16  that redirects the force being applied by driver rail  22  and avoids further downward movement of driver  20  and further insertion of a staple into work piece  5 . Inspection of the shape of cam  16  as shown in  FIGS. 1-4  shows that the path of force-applying leg  32  of cam  16  is generally in a straight line with, or parallel to, the direction of travel of driver rail  22 . In contrast, the path of force-redirecting leg  34  of cam  16  changes to a direction that is approximately 22 degrees from the path of force-applying leg  32 . This change in path direction results in the downward force from driver rail  22  being redirected along the path established by force-redirecting leg  34  with some of the force being put to the purpose of pivoting the force-applying leg  32  and the force-redirecting leg  34  about cam follower transition roller  18 . This redirection of the force being delivered by driver rail  22  results in reduction and termination of the downward movement of driver  20  and the force delivered to driver  20  from driver rail  22 . 
     Interlock and Release Mechanism for Engagement of Bender Rail with Driver for Driver Rail with Driver 
     Referring now to  FIG. 5  an embodiment is shown for the releasable interlocking or engagement of bender rail  82  with driver  80  and for the releasable interlocking or engagement of for drive rail  88  with driver  80  during the staple insertion process. It will be appreciated that while different reference numbers are now employed the continuation of the same or similar structure names as used on  FIGS. 1-4  is intended to reference the same or similar structures as was presented previously in those figures. In  FIG. 5  driver  80  is shown interlocked with bender rail  82  as flange  84  is spring biased, or mechanically pressed, to be rotated to contact shoulder  86  of bender rail  82  thereby connecting the bender rail  82  with the driver  80  for joint movement as the driver  80  receives force from the driver rail  88 . Also shown in  FIGS. 5 and 6  is the interlocking of driver  80  with driver rail  88  by the abutting of hip  90  ( FIG. 6 ) of flange  92  on shoulder  91  of driver rail  88 . It will be appreciated by those skilled in the art that with bender rail  82  and driver  80  and drive rail  88  connected together that the downward motion of these structures begins the formation of the staple  7  ( FIG. 1 ) as the force from the actuator bar (not shown) is communicated through the drive rail  88  to the bender rail  82  to shape wire into a staple having a crown and two legs extending from either end of the crown. 
     Still referring to  FIGS. 5 and 6 , driver  80  is released from engagement with bender rail  82 . The disengagement is achieved as the result of cam follower  94  on flange  84  being pressed inwardly to caused flange  84  to be rotated off of shoulder  86  as cam follower  94  arrives at Point B on cam  96 . This allows driver  80  to continue to move separately from bender rail  82  to continue downward movement to force the staple through the workpiece. Bender rail  82  has previously ended its movement downward upon bender rail  82  contacting the workpiece (not shown). 
     In  FIGS. 6 and 7 , driver  80  is unlocked from driver rail  88  by the rotation and release of hip  90  of flange  92  from engagement or interlock with shoulder  91  on driver rail  88 . This disengagement or release occurs when driver  80  reaches the end or tip of bender rail  82  which is in contact with the workpiece  5 . It is at this point in the operation of stitching head  10  that the staple  7  has been inserted into the workpiece  5  and further downward movement of driver  80  is not needed and would cause the staple  7  to be driven too far into the work piece  5 . 
     The increased resistance driver  80  receives upon contacting the workpiece  5  at the conclusion of the staple  7  insertion is sufficient to urge flange  92  to move hip  90  along shoulder  91  which results in the rotation of flange  92  against flexible rod  93  which has, up to this point in the operation, biased hip  90  of flange  92  against shoulder  91 . This rotation of flange  92  allows the disengagement of hip  90  from shoulder  91  and the disengagement of driver  80  from driver rail  88 . As a result driver  80  is released from drive rail  88  and the additional downward movement of the driver rail  88  as caused by the actuator bar (not shown) does not transmit force to the driver  80 .