Abstract:
A sewing direction control apparatus for sewing machine, comprising: a base plate, a circular ring-shaped transmission element dispose on the base plate and a driving element with a driving unit. During sewing, the driving unit drives the transmission element, rotating a sewing product placed at the center of the transmission element with the driving element, thereby controlling the sewing direction of the sewing product, and thus improving the sewing accuracy. The direction control apparatus has low cost, and is suitable for various types of automatic sewing machines.

Description:
This application is a continuation in part of U.S. patent application Ser. No. 13/880,049, which claims the benefit of the earlier filing date of May 31, 2013. Claims  1  and  4  of this application are revised from claim 1 of U.S. patent application Ser. No. 13/880,049, respectively, claims  2 ,  3  and  5  of this application corresponds to claims 2, 3 and 5 of U.S. patent application Ser. No. Claims  1  and  4  of this application are revised from claim 1 of U.S. patent application Ser. No. 13/880,049, respectively, and claims  6  and  7  are new. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an automatic sewing machine, and more particularly to a sewing direction control apparatus for sewing machine. 
     2. Description of the Prior Art 
     Computer control sewing machines are usually used to embroider complicated patterns automatically rather than manually, whereby to enhance the quality of the embroidery pattern, or used to stitch buttons or create decorative patterns on sewing products, whereby to improve sewing speed or accuracy. The existing computer control sewing machine essentially comprises a clamp on a work platform to clamp and fix the sewing product to be embroidered, the clamp is driven by a movement device to perform two-dimensional movement on the work platform with respect to the sewing head of the sewing machine, and the sewing product will move along with the clamp, so that patterns can be embroidered on the sewing product. 
     The sewing head of the existing computer control sewing machines is designed to be able to sew the sewing product only in a specific direction, so that the sewing product has to be inserted from the specific direction into the sewing head and should be aligned to the needle, then the sewing thread above the sewing machine can be formed into a loop to form lock stitch seam by cooperating with the sewing thread from the thread spool which is at the lower portion of the sewing machine. However, when moving in a two-dimensional manner along the work platform, the sewing product might approach the needle from any direction, resulting in poor stitching or deviation of sewing thread. 
     To solve the above defects, U.S. Pat. No. 4,498,404 discloses an automatic sewing apparatus which uses a manipulator arm to replace the conventional 2D movement device. The manipulator arm includes three rotation axes, so that the sewing product can be better controlled by the manipulator arm to rotate between the needle and the work platform, ensuring that the sewing product is kept being inserted into the sewing head from a specific direction. An Italian patent B093A 000113 discloses another sewing apparatus, wherein a lever with a needle is arranged above the needle plate of the sewing head, and below the needle plate is disposed a thread shaft with a hook. The lever and the thread shaft rotate together to maintain the relative position between the needle and the hook unchanged, ensuring that the sewing product is kept being inserted into the sewing head from a specific direction. 
     However, the above two sewing apparatuses still have the following disadvantages: 
     1. for automatic sewing machines, the sewing product must be moved intermittently and rapidly a very small distance at a time during sewing operation, so that the manipulator arm for moving the sewing product should have excellent acceleration ability and should be capable of precisely controlling the distance that the sewing product moves, resulting in a high manufacturing and maintenance cost of the manipulator arm. 
     2. there are various types of automatic sewing machines, however, the positioning device which maintains the relative position between the needle and the hook unchanged by using the synchronous rotation of the lever and the thread shaft is inapplicable to the sewing machines with cylinder bed head. Therefore, it is still unable to solve the sewing direction problem. 
     The present invention has arisen to mitigate and/or obviate the afore-described disadvantages. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a low cost sewing direction control apparatus for sewing machine which provides accurate sewing operation and is suitable for use in various automatic sewing machines. 
     To achieve the above objective, a sewing direction control apparatus for sewing machine in accordance with the present invention comprises: 
     a base plate being an X-Y planar surface with an X direction and a Y direction, a lateral edge of the base plate in the X direction being provided with a drive portion which includes a gap and two assembling holes at two ends of the gap; 
     a transmission element being a circular ring-shaped structure mounted on the base plate and centrally provided with a circular cavity and a threaded surface around an outer peripheral surface thereof, the transmission element being disposed on the base plate and having the threaded surface protruded out of the gap of the drive portion, a sewing product being fixed at a bottom of the cavity and located corresponding to the needle; 
     a slide rack disposed at an outer surface of the drive portion of the base plate and provided with a passage aligned to the gap of the drive portion, and two abutting protrusions aligned to the two assembling holes of the drive portion, the slide rack being provided with a Y-direction displacement mechanism and an X-direction displacement mechanism to drive the slide rack to move in X and Y directions, the Y-direction displacement mechanism pushing the two abutting protrusions to move into the two assembling holes, and the X-direction displacement mechanism driving the slide rack and the base plate to move in the X direction; and 
     a driving element mounted on the slide rack and including a disc-shaped driving unit, the disc-shaped driving unit being formed with a threaded surface around an outer peripheral surface and extending out of the passage of the slide rack, the slide rack driving the driving unit to move in the Y direction, so that the driving unit is able to engage with the threaded surface to simultaneously rotate the transmission element and the sewing product, or the driving unit is able to disengage from the threaded surface to stop the transmission element from rotation. 
     The sewing direction control apparatus for sewing machine in accordance with the present invention uses teeth engagement to perform highly accurate, intermittent and fast movement, therefore, the direction control apparatus of the present invention has low cost, and is suitable for various types of automatic sewing machines. In addition, the base plate and the slide rack are connected in the same Y direction while being able to move synchronously in the X direction, and the transmission element can be controlled to rotate or stop rotation by the engagement or disengagement between the threaded surface of the transmission element and the driving unit of the driving element, such arrangements prevent the problem that the sewing direction is not readily controllable in case of multi-directional connection. Furthermore, with the slide rack, the driving element is movable in the Y direction, so that it can be engaged with the threaded surface to rotate the transmission element during sewing, and when sewing stops, the driving element will be disengaged from the threaded surface to improve safety of the sewing direction control apparatus for sewing machine of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a sewing direction control apparatus for sewing machine in accordance with a preferred embodiment of the present invention; 
         FIG. 2  is a cross sectional view of the sewing direction control apparatus for sewing machine in accordance with the preferred embodiment of the present invention; 
         FIG. 3A  is an operational view showing that the slide rack of the present invention moves away from the base plate; 
         FIG. 3B  is an operational view showing that the slide rack of the present invention is engaged with the base plate; 
         FIG. 4  is a perspective view of a sewing direction control apparatus for sewing machine in accordance with another preferred embodiment of the present invention; 
         FIG. 5  is a cross sectional view of the sewing direction control apparatus for sewing machine in accordance with the another preferred embodiment of the present invention; 
         FIG. 6  is an operational view of the sewing direction control apparatus for sewing machine in accordance with the another preferred embodiment of the present invention; and 
         FIG. 7  is a side view of  FIG. 3A . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be clearer from the following description when viewed together with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment in accordance with the present invention. 
     Referring to  FIGS. 1 and 2 , a sewing direction control apparatus for sewing machine in accordance with a preferred embodiment of the present invention comprises a base plate  10 , a transmission element  20  disposed on the base plate  10 , a sewing plate  30  disposed in the transmission element  20  to fix a sewing product A, and a slide rack  40  and a driving element  50  disposed at one side of the base plate  10 . 
     The base plate  10  is rectangular and centrally provided with a hole  11  and a flange  12  around the hole  11 . The base plate  10  is an X-Y planar surface with an X direction and a Y direction. A lateral edge of the base plate  10  in the X direction is provided with a drive portion  15  which includes a gap  151  and two assembling holes  152  at two ends of the gap  151 . 
     In this embodiment, as shown in  FIG. 1 , the base plate  11  is further provided with two protrusions  13  which are located adjacent to the hole  11  and a corner of the base plate  11 , and the drive portion  15  is a lateral plate disposed along the lateral edge of the base plate  10 . 
     The transmission element  20  is a circular ring-shaped structure located around the hole  11  of the base plate  10 . As shown in  FIG. 2 , the transmission element  20  is centrally provided with a circular cavity  21 , an annular slot  211  around the bottom of the circular cavity  21 , and a plurality of positioning pins  212  disposed at the bottom of the cavity  21  and located around the bottom of the annular slot  211 . An annular engaging portion  22  extending outward from the bottom of the cavity  21  is formed with an annular groove  221  which is located around the periphery of the transmission element  20 . The annular groove  221  and the cavity  21  open in opposite directions and separated from each other by the wall of the cavity  21 . The transmission element  20  is provided with a threaded surface  23  around the outer peripheral surface of the annular engaging portion  22 . The annular groove  221  of the transmission element  20  is located corresponding to the flange  12  of the base plate  10 , namely, the flange  12  is received in the annular groove  221 , and an annular bearing  24  is disposed between the flange  12  and the annular groove  221  to enable the transmission element  20  to rotate with respect to the flange  22 . The transmission element  20  is disposed on the base plate  10  and has the threaded surface  23  protruded out of the gap  151  of the drive portion  15 . In this embodiment, the transmission element  20  is provided with four spaced positioning pins  212 . 
     The sewing plate  30  is a circular structure received in the cavity  21  of the transmission element  20  and provided with a plurality of ears  31  around a periphery thereof. The ears  31  each have a pivot hole  311  and are located corresponding to the positioning pins  212  of the transmission element  20  in such a manner that the positioning pins  212  of the transmission element  20  are inserted in the pivot holes  311  of the sewing plate  30 , so as to fix the sewing plate  30  to the annular slot  211  of the transmission element  20 . In this embodiment, the sewing plate  30  is provided with four spaced ears  31  to cooperate with the positioning pins  212 . 
     The slide rack  40 , as shown in  FIG. 1 , is disposed on the X-Y surface and fixed at the outer surface of the drive portion  15  of the base plate  10 . The slide rack  40  a rectangular structure which is centrally provided at a top surface thereof with a rack plate  41  which is located higher than the X-Y surface. The slide rack  40  is provided with a passage  42  aligned to the gap  151  of the drive portion  15 , and two abutting protrusions  43  aligned to the two assembling holes  152  of the drive portion  15 . The slide rack  40  is provided with a Y-direction displacement mechanism  44  and an X-direction displacement mechanism  45 , so that the slide rack  40  is capable of moving in both X and Y directions, the Y-direction displacement mechanism  44  makes the two abutting protrusions  43  move into the two assembling holes  152 , and the X-direction displacement mechanism  45  drives the slide rack  40  and the base plate  10  to move in the X direction. 
     In this embodiment, the Y-direction displacement mechanism  44  and the X-direction displacement mechanism  45  can be a linear guideway or ball screw, which are used independently or together to make the slide rack  40  move in X and/or Y direction. When the Y-direction displacement mechanism  44  and the X-direction displacement mechanism  45  are ball screws, as shown in  FIG. 7 , the Y-direction displacement mechanism  44  is provided with a slide hole  441  formed in the slide rack  40  and extending in the Y direction, a Y-direction screw  442  screwed in the slide hole  441 , and a servo motor  443  which is disposed at the end of the screw  442  to drive the slide rack  40  to move with respect to the Y-direction screw  442 . The X-direction mechanism  45  includes a slide block  451  which is mounted on the slide rack  40  and disposed in the X direction, an X-direction screw  452  screwed with the slide block  451 , and a servo motor  453  which is disposed at the end of the X-direction screw  452  to drive the slide rack  40  to move with respect to the X-direction screw  452 . 
     When the Y-direction displacement mechanism  44  and the X-direction displacement mechanism  45  are linear guideways, the Y-direction displacement mechanism  44  includes a Y-direction slide block (not shown) disposed on the slide rack  40 , a Y-direction rail (not shown) extending in the Y direction, and a power source (not shown) for moving the Y-direction slide block. The X-direction displacement mechanism  45  includes an X-direction slide block (not shown) mounted on the slide rack  40 , an X-direction rail (not shown) extending in the X direction, and another power source (not shown) for driving the X-direction slide block to move in the X direction. 
     The driving element  50 , as shown in  FIG. 1 , is mounted on the slide rack  40  and comprises a servo motor  51  disposed on the rack plate  41 , a driving shaft  511  located below the servo motor  51  and inserted in the rack plate  41 , and a driving unit  52  connected to one end of the driving shaft  511 . The driving unit  52  is a disc structure. In this embodiment, around the outer peripheral surface of the driving unit  52  is formed a threaded surface, and the end of the driving shaft  511  is connected to the center of the driving unit  52 . The driving unit  52  is located on the X-Y surface and extends out of the passage  42  of the slide rack  40 , and the slide rack  40  drives the driving unit  52  to move in the Y direction, so that the driving unit  52  can be meshed with the threaded surface  23  to simultaneously rotate the transmission element  20  and the sewing product A. 
     A control element  60 , as shown in  FIGS. 1 ,  3 A and  3 B, is pivoted to the two protrusions  13  of the base plate  10  and comprises a control unit  61  and an elastic unit  62 . The control unit  61  is reversed U-shaped and includes an operating section  611 , a connecting section  612  and an engaging section  613 . A conjunction between the operating section  611  and the connecting section  612  is pivoted to one of the protrusions  13  adjacent the transmission element  20 , so that the operating section  611  and the engaging section  613  approximately extend in the direction X and toward the transmission element  20 , and the free end of the engaging section  613  is a threaded structure. The elastic unit  62  is approximately L-shaped and includes a stationary section  621  and an abutting section  622 . A connecting hole  623  is formed at the conjunction between the stationary section  621  and the abutting section  622  to enable the elastic unit  62  to be pivoted to the one of the protrusions  13  adjacent the transmission element  20  in such a manner that the end of the stationary section  621  of the elastic unit  62  is pressed against another one of the protrusions  13  which is located farther away from the transmission element  20 , and the end of the abutting section  622  is pressed against the connecting section  612  of the control unit  61 . 
     As shown in  FIG. 3A , when the base plate  10  moves away from the slide rack  40 , the connecting section  612  of the control unit  61  will be pushed by the abutting section  622  of the elastic unit  62 , the engaging section  613  of the control unit  61  will be engaged with the threaded surface  23  of the transmission element  20 , and the driving unit  52  of the driving element  50  will be disengaged from the transmission element  20  to enable the transmission element  20  to be engaged with and fixed by the control unit  61 . As shown in  FIG. 3B , when the base plate  10  move toward the slide rack  40 , the operating section  611  of the control unit  61  will be pushed by the abutting protrusion  43  of the slide rack  40 , so that the engaging section  613  of the control unit  61  will be disengaged from the threaded surface  24  of the transmission element  20 , and the driving unit  52  of the driving element  50  will be engaged with the threaded surface  24  of the transmission element  20  to enable the transmission element  20  to be rotated by the driving unit  52 . 
     The abovementioned are the structural relations of the main components of the first preferred embodiment. It is to be noted that the present invention also provides another embodiment; its structure is explained as follows. 
     Referring to  FIGS. 4 and 5 , in this embodiment, around an outer peripheral surface of the annular engaging portion  22  of the transmission element  20  is provided a driven belt  25 , and a driving belt  53  winds around the driven belt  25  and the driving unit  52  of the driving element  50  to rotate the transmission element  20 . At a corner of the base plate  10  is disposed a pallet  14  which is higher than the X-Y surface. The servo motor  51  of the driving element  50  is inserted in the pallet  14 , the driving shaft  511  of the servo motor  51  is connected to the driving unit  52 , the driven belt  25  of the transmission element  20  located toward the driving unit  52 , and the driven belt  53  winds around the driven belt  25  and the driving unit  52  of the driving element  50 . When the servo motor  51  rotates the driving unit  52 , the driving unit  52  will drive the transmission element  20  to rotate on the base plate  10  via the driving belt  53 . In this embodiment, the driven belt  25  and the driving belt  53  are timing belts, which are engaged with each other via teeth engagement. 
       FIG. 6  shows that the sewing direction control apparatus for sewing machine in accordance with the present invention is used in combination with a needle  71  of a sewing head  70 . As shown in  FIG. 6 , when the slide rack  40  moves toward the base plate  10 , the sewing product A is fixed on the sewing plate  30  and located corresponding to the needle  71  of the sewing head  70 , and the preset sewing path of the needle  71  extends along the direction Y. The transmission element  20  is rotated by the driving element  50 . Meanwhile, the sewing product A is caused to rotate clockwise, so that the sewing direction is maintained tangent to the rotation direction of the sewing product A, thus fixing the sewing direction of the sewing machine, making the sewing machine perform sewing operation by moving along the desired sewing direction, and consequently improving the sewing speed and quality. Furthermore, the sewing direction control apparatus for sewing machine in accordance with the present invention uses teeth engagement to perform highly accurate, intermittent and fast movement, therefore, the direction control apparatus of the present invention has low cost, and is suitable for various types of automatic sewing machines. 
     In addition, the base plate and the slide rack are connected in the same Y direction while being able to move synchronously in the X direction, and the transmission element can be controlled to rotate or stop rotation by the engagement or disengagement between the threaded surface of the transmission element and the driving unit of the driving element, such arrangements prevent the problem that the sewing direction is not readily controllable in case of multi-directional connection. Furthermore, with the slide rack, the driving element is movable in the Y direction, so that it can be engaged with the threaded surface to rotate the transmission element during sewing, and when sewing stops, the driving element will be disengaged from the threaded surface to improve safety of the sewing direction control apparatus for sewing machine of the present invention. 
     While we have shown and described various embodiments in accordance with the present invention, it is clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.