Patent Publication Number: US-10323347-B2

Title: Pallet drive system for moving a work-piece

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. § 371 to PCT/US2016/017374, filed on Feb. 10, 2016, entitled “Pallet Drive System for Moving a Work-Piece,” which claims priority to Vietnamese Patent Application No. 1-2015-00527, filed Feb. 11, 2015, entitled “Pallet Drive System for Moving a Work-Piece,” the entirety of the aforementioned applications is incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     Industrial sewing machines exist that move a work-piece relative to a sewing needle using a pallet drive system. The pallet maintains the work-piece(s) in position, and the drive system moves the pallet, and thus the work-piece, relative to the sewing needle. Oftentimes, however, these drive systems fail to accurately position the work-piece. Additionally, existing pallet drive systems are expensive. 
     SUMMARY OF THE INVENTION 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential elements of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The present invention is defined by the claims. 
     At a high level, aspects herein relate to a pallet drive system operable for use on a sewing system having a sewing head, with a sewing needle operable to perform a sewing operation on a work-piece. The sewing system has a mounting horn that operates to move the work-piece relative to the sewing needle. The pallet drive system has a pallet that is configured to hold the work-piece in position. A pair of alignment posts is coupled to the pallet. In exemplary aspects, each alignment post has a shape with surfaces extending in three dimensions along x, y and z axes. The mounting horn has a corresponding pair of gripping fingers coupled thereto, for each alignment post, that are moveable between an open position, allowing the alignment post to be positioned between the gripping fingers, and a closed position where the gripping fingers surround the alignment post. The gripping fingers define a cavity in the closed position to surround the corresponding alignment post in the x, y and z axes. Therefore, as the mounting horn moves, the movement of the work-piece, through the pallet, is moved correspondingly. 
     The configuration of the above-described pallet drive system provides for several advantages. As just one example, and without limitation, the gripping fingers more-accurately position the pallet and the work-piece by surrounding the alignment post in three dimensions. As another example, the gripping fingers are symmetrically designed to allow them to be used interchangeably as either a left or right-side finger. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Examples are described in detail below with reference to the attached drawing figures, wherein: 
         FIG. 1  illustrates a perspective view of an exemplary pallet drive system in accordance with aspects hereof; 
         FIG. 2  is a simplified view similar to  FIG. 1  with certain parts omitted for clarity; 
         FIG. 3  provides an enlarged view of the encircled region of  FIG. 2 ; 
         FIG. 4  is a view similar to  FIG. 3 , showing the gripping fingers in a closed position; 
         FIG. 5  provides a partial front plan view of the area of  FIG. 2 , with parts being broken away to show particular details of construction; 
         FIG. 6  provides an exploded view of selected components; and 
         FIG. 7  provides an exploded view of the gripper and gripping fingers. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Aspects herein relate to a pallet drive system operable for use on a sewing system having a sewing head, with a sewing needle operable to perform a sewing operation on a work-piece. The sewing system has a mounting horn that operates to move the work-piece relative to the sewing needle. The pallet drive system has a pallet that is configured to hold the work-piece in position. A pair of alignment posts is coupled to the pallet. In exemplary aspects, each alignment post has a shape with surfaces extending in three dimensions along x, y and z axes. The mounting horn has two corresponding pairs of gripping fingers coupled thereto that are moveable between an open position, allowing the alignment posts to be positioned between the gripping fingers, and a closed position where the gripping fingers surround the alignment post. The gripping fingers define a cavity in the closed position to surround the corresponding alignment post in the x, y and z axes. This configuration accurately and repeatably positions the work-piece, through the pallet, relative to the mounting horn and sewing needle. 
       FIG. 1  depicts an exemplary sewing system  10  that will be described for reference purposes. Industrial sewing machines have a sewing head  12  that operates a reciprocating sewing needle  14 . The sewing system  10  operates to move a pallet  16  relative to the sewing needle. The pallet  16  typically has a pattern  18  formed in it, as well as an access window  20 . Access window  20  can be, for example, a pair of hinged doors  22  coupled to the pallet, and forming a part of the pallet. The access window  20  is used to position one or more work-pieces  24  within the access window  20 . The hinged doors  22  are then held in a closed position to retain the work-pieces  24  in the proper position. Other mechanisms for positioning and holding the work-pieces  24  can also be used. 
     As best seen in  FIGS. 2, 3 and 6 , the pallet  16  includes a pair of post-holders  26 .  FIG. 2  illustrates only portions of the pallet and sewing system to more completely show other portions. As seen in  FIG. 6 , each post holder  26  has a pair of locating holes  28 , and a pair of threaded bolt holes  30 . The locating holes  28  are used with a pair of corresponding locating holes  31  on pallet  16  and dowel pins  34  to precisely locate the post-holders  26  on pallet  16 . The bolt holes  30  are used, along with corresponding holes  33  in post holder  26 , and bolts  32  to couple the post-holders to the pallet  16 . It should be understood that other location and connection mechanisms could also be used. 
     As best seen in  FIG. 6 , each post-holder  26  also includes a post-hole  36 . With continued reference to  FIG. 6 , an alignment post  38  is press-fit into the post holder  26 . Alignment post  38  has an upper section  40 , a lower section  42  and a locating pin  44 . The upper section  40 , in one aspect is a disc-shape; with the lower section  42  extending from the upper section, and being of a smaller-diameter disc-shape. The locating pin  44  extends from lower section  42 , and is precisely shaped and sized to be press-fit into the post hole  36  in post holder  26 . Other attaching mechanisms could also be used to couple alignment post  38  to post holder  26 . 
     In some aspects, a sensor flag  46  is also coupled to the post holder  26  near alignment post  38  using bolts or screws  39 . Sensor flag  46  is used to determine when the pallet  16  and work-piece  24  are in position and ready to be sewn, as further described below. In other aspects, portions of the pallet  16 , post holder  26  or alignment post  38  could also be used as the object of detection. 
     As noted above, the sewing system  10  moves the pallet  16  relative to the sewing needle  14 . As best seen in  FIGS. 1 and 2 , typically, the sewing head  12  includes a horn, or drive head,  48 . The horn  48  is coupled to the sewing machine, and moves according to the desired stitching path needed for the work-piece  24 . The horn  48  has a back end  50  coupled to the drive system of the sewing machine, and a mounting face  52 . The mounting face  52  is configured with a number of mounting holes which are used to couple the remaining attachment components described below. 
     A yoke  54  is coupled to the horn  48  using at least some of the mounting holes on face  52 . As one example, the yoke  54  may be coupled to the horn  48  using a number of bolts. The yoke  54  supports and positions a spacer plate  58 . The spacer plate  58  may be coupled to the yoke  54  using a number of bolts. Other coupling mechanisms, beyond the bolts, may be used to couple the horn  48 , yoke  54  and spacer plate  58 . In an exemplary aspect, the yoke  54  and spacer plate  58  are made from a suitable steel material, although other materials could be used as well. The horn  48 , yoke  54  and spacer plate  58  are rigidly secured together, such that no relative movement between the parts is allowed. As best seen in  FIG. 5 , a proximity sensor  61  is coupled to spacer plate  58 . As more-fully described below, proximity sensor  61  is configured to detect the presence of the sensor flag  46 , indicating the pallet  16  is in position and ready. As noted above, in alternative aspects, the sensor  61  could also be positioned and configured to detect the proper position of the pallet  16 , such as the post holders  26  or the alignment post  38 . As partially seen in  FIGS. 3 and 4 , a bracket  63  may be coupled to spacer plate  58  to protect the sensor  61  from damage, such as by contact from adjacent parts. If used, bracket  63  is rigidly coupled to spacer plate  58 , such as by bolting or other attachment mechanisms. 
     As best seen in  FIGS. 2 and 3 , a bracket  62  is also positioned on spacer plate  58 . The bracket  62  is held on spacer plate  58 , such as through a number of bolt holes in spacer plate  58  and corresponding bolts. The bracket  62  extends forwardly from the spacer plate  58  opposite the yoke  54 . The bracket  62  is sized to hold a gripper mechanism  68  in the proper position. The gripper mechanism  68  is rigidly coupled to the bracket  62 , such as with a pair of bolts  70 . Alternatively, the gripper mechanism  68  may be secured directly to the spacer plate  58 . Like the yoke  54  and spacer plate  58 , the bracket  62  is preferably made from a suitable steel material, although other materials could be used. The gripper mechanism  68  has a pair of reciprocating jaws  72  that operate to move toward and away from one another. The jaws  72 , in an exemplary aspect, are pneumatically operable to open and close. A pair of ports  74  is provided in gripper  68  to selectively provide air pressure to open and close the jaws  72 . Alternatively, the jaws may be biased to either the open or closed position, such as by spring pressure, and pneumatic pressure is applied to overcome the biasing force to either open or close the jaws. Commercially available parallel grippers may be used, such as those available from the De-Sta-Co company of Auburn Hills, Mich. 
     As best seen in  FIGS. 5 and 7 , a gripping finger  76  is positioned on each jaw  72 . Preferably, each finger  76  has a pair of locating holes that are used in combination with a pair of dowel pins  80  to position the finger  76  on the jaw  72 . Each finger  76  also has a number of bolt holes  82  that are used, in combination with bolts  84 , to rigidly secure the finger  76  to the jaw  72  using corresponding threaded holes in jaw  72 . As the jaws  72  reciprocate open and closed on gripper  68 , the fingers  76  correspondingly reciprocate open and closed. Each finger  76  has a cavity  86 . Cavity  86  is shaped and sized to capture the alignment post  38  when the pallet  16  is moved into a position to stitch the work-pieces  24 . In one aspect, cavity  86  is shaped as a semi-circle having a height corresponding to the height of the upper section  40  of alignment post  38 . Each cavity  86  thus has an upper surface  88 , a lower surface  90  and in inner, arcuate surface  92  having a radius corresponding to the radius of upper section  40  of alignment post  38 . Immediately below lower surface  90 , finger  76  has a lower arc face  94  that has a radius corresponding to the lower section  42  of alignment post  38 . The shape and size of cavity  86  and lower arc face  94  thus allow the material of finger  76  around cavity  86  and lower arc face  94  to completely surround alignment post  38  when the fingers  76  are moved to the closed position shown in  FIG. 4 . Preferably, each finger is usable as either the left or right finger, the left and right fingers being mirror-images of one another. Such a construction allows the fingers  76  to be used interchangeably and reduces the overall costs of the system. 
     In use, one or more work-pieces  24  are placed within the pallet  16  using the hinged doors  22  to open the access window  20 . The pallet  16  is then moved into place for sewing, moving the alignment posts  38  between the open fingers  76 , as shown in  FIGS. 2 and 3 . When the alignment posts  38  are in this position, the proximity sensor  61  detects the presence of the pallet through the sensor flags  46  (or in other aspects, the post holders  26  or alignment posts  38 ). In this position, the system uses a logic controller to signal the gripper  68  to move the jaws  72 , and thus the fingers  76 , to the closed position shown in  FIG. 4 . In the closed position, the cavities  86  of mating fingers  76  enclose the alignment post  38 . The fingers  76 , through the cavities  86  retain the alignment posts  38  in position with multiple contact surfaces in a three-dimensional fashion in the x, y and z directions. The accurate and precise positioning of the post holder  26  on pallet  16 , along with the accurate and precise positioning of each alignment post  38  on post holder  26 , coupled with the positive positioning achieved with fingers  76  allows for a repeatable, reliable positioning of the work-pieces  24  relative to the sewing needle  14 . Additionally, by providing a pallet  16  with post holders  26  and alignment posts  38  consistently positioned on the pallet  16 , the pallet  16  is usable on different sewing systems  10 , provided they are equipped with the above-described yoke  54 , spacer plate  58 , gripper  68  and fingers  76 . 
     Many different arrangements of the various components depicted, as well as components not shown, are possible without departing from the scope of the claims below. Aspects of our technology have been described with the intent to be illustrative rather than restrictive. Alternative aspects will become apparent to readers of this disclosure after and because of reading it. Alternative means of implementing the aforementioned can be completed without departing from the scope of the claims below. Certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations and are contemplated within the scope of the claims.