Abstract:
A buttonhole sewing machine for the production of a group of at least two buttonholes of varying design and/or size comprises devices for the entry, storage and processing of information on the varying design and/or size of the group of buttonholes and a device for triggering the drives for the successive production of buttonholes on the workpiece.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a buttonhole sewing machine for the production of a group of buttonholes on a workpiece, the group having at least two buttonholes of varying design and/or size, the buttonhole sewing machine comprising a needle, which is mounted in an arm, and which is drivable to reciprocate in a Z direction by means of a driving motor, and which is drivable by a jogging drive for the production of a zigzag seam by a motion of the needle relative to the workpiece, and which is drivable to pivot about an axis by means of a pivot drive; a hook bearing, which is disposed in a base plate, and which is drivable by a pivot drive to pivot synchronously and equiangularly of the needle about a pivot axis which extends in the Z direction; a hook, which is disposed in the hook bearing; a stitch hole, which is allocated to the needle and the hook; a holder for the workpiece, which holder is displaceable by drives in an X direction and a Y direction; and an operating and control unit. 
     2. Background Art 
     In a buttonhole sewing machine of the generic type known from U.S. Ser. No. 09/063,965, U.S. Pat. No. 6,006,685 the workpiece holder in the form of an X-Y table is actuated by two stepper motors. Furthermore, the needle bar and the hook bearing are driven synchronously and equiangularly by a stepper motor so that the sewing tools are rotatable about the axis of the needle, which helps attain a constant position of the sewing tools relative to the direction of sewing and thus considerable flexibility of the machine as regards the geometry of the seam. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to embody the buttonhole sewing machine of the generic type such that a group of buttonholes of varying design and/or dimensions can be sewn by it successively, there being no need of manual adjustment of the machine. 
     According to the invention, this object is attained by devices for the entry, storage and processing of information about the varying design and/or size of the group of buttonholes; and by a device for triggering the drives for the successive production of the buttonholes on the workpiece. The measures according to the invention help attain that all the relevant parameters of buttonholes that are to be produced successively at a single work place, i.e. by one and the same buttonhole sewing machine, are entered in advance and that the buttonholes are then sewn one after the other. The buttonholes can be cut if a cutter is provided for the production of an incision in the zigzag seam; if the operating and control unit comprises means for the entry, storage and processing of information about the execution and non-execution and the type of the incision; and if the device for triggering the drives also comprises means for triggering the cutter. In this case it is of no importance whether cutting the buttonholes takes place in the pre- or after-cutting mode. 
     Provision is made for a gimp thread feeder, which is very often desired, automatic feeding and cutting of the gimp thread being provided within the scope of automation of the sewing operation of the varying buttonholes. Of course, this design of the gimp thread feeder can also be employed when buttonholes are sewn successively which are identical in design and size and/or when no automation is provided. 
     Details of the invention will become apparent from the ensuing description of an exemplary embodiment, taken in conjunction with the drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is an elevation of a buttonhole sewing machine; 
     FIG. 2 is a front view of an X-Y table according to the arrow II of FIG. 1; 
     FIG. 3 is a diagrammatic illustration of a vertical section of a gimp thread feeder according to the arrow II of FIG. 1 during a sewing job; 
     FIG. 4 is an illustration of the gimp thread feeder according to FIG. 3 during the cutting of a gimp thread; 
     FIG. 5 is an illustration of the gimp thread feeder according to FIG. 3 during the feed of a gimp thread prior to the start of a sewing job; 
     FIG. 6 is a view of a cutter on an enlarged scale as compared to FIG. 1; 
     FIG. 7 is a view of a workpiece in the form of a jacket forepart comprising four buttonholes of three different types which are to be sewn; 
     FIG. 8 is a diagrammatic illustration of a straight buttonhole; 
     FIG. 9 is an illustration of an eye type buttonhole; 
     FIG. 10 is an illustration of an eye type buttonhole with a stitched transverse lock; 
     FIG. 11 is a diagrammatic illustration of an operating and control unit of the sewing machine; and 
     FIG. 12 is an input diagram for illustration of the entry of buttonhole parameters. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The single/double thread chain stitch sewing machine seen in FIG. 1 comprises a housing  1 , which substantially consists of a so-called base plate  2 , a standard  3  and an upper arm  4 . An arm shaft  5  is rotatably run in the arm  4  and can be driven in rotation by means of a driving motor  6  via a belt drive  7 . 
     Mounted in the arm  4  in bearings  9 ,  10  is a substantially vertical needle bar  8 , which can be driven to reciprocate by the arm shaft  5  via a crank drive  11 . At its lower end, the needle bar  8  is provided with a needle  12 . 
     Underneath the needle bar  8 , a hook bearing  13 , which comprises a chain stitch hook  14  (FIG.  3 ), is mounted in bearings  15 ,  16  for rotation by approximately 400° about a vertical pivot axis  17  which extends in the Z direction. Rotary actuation of the hook bearing  13  takes place via two belt drives  19 ,  20  by means of a stepper motor which serves as a pivot drive  18 . The needle bar  8  is mounted in the bearings  9 ,  10  not only for displacement in the longitudinal direction, but also for rotation about the pivot axis  17 . Via a setting shaft  21 , which is drivable by the belt drive  19  and extends in the Z direction, and via a further belt drive  22 , it is driven synchronously and equiangularly of the hook bearing  13  by the pivot drive  18  so that the needle  12  and the hook bearing  13  are synchronously and equiangularly pivoted about the pivot axis  17 . 
     The needle bar  8  and the needle  12  are drivable to jog laterally, i.e. to swing, by means of a needle jogging drive  23 . The lateral jogging motion is accompanied with a deflection of the needle bar  8  relative to the pivot axis  17 . Due to the rotatability of the needle bar  8 , the jogging plane of the needle bar  8  with the needle  12  is displaceable synchronously and equiangularly of the position of rotation of the hook bearing  13 . A stepper motor  25  is provided for the lateral jogging of the needle bar  8 , this stepper motor  25  acting on the needle bar  8  by way of a jogging shaft  28 , which is run in bearings  26 ,  27 . To this end, provision is made for a transmission  29  (not shown in detail), which is known from U.S. Pat. No. 1,991,627 and U.S. patent application Ser. No. 09/256,853, U.S. Pat. No. 6,095,066. 
     An X-Y table  30  (seen in detail in FIG. 2) is disposed on the base plate  2 ; it is mounted on guide rods  31  which extend in the X direction and it is displaceable in this direction. By means of connecting rods  32 , the guide rods  31  are supported on rods  33  which are mounted in the base plate  2  and extend in the X direction. The connecting rods  32  cooperate with the rods  33  and the guide rods  31  and the table  30  to form a parallel rod guide, by means of which the table  30  can be displaced parallel to itself in the Y direction. In doing so, it makes slight motions in the Z direction which are however negligible because of their minor significance. The described motion of displacement of the table in the Y direction takes place by means of a stepper motor  34  which is coupled with one of the rods  33  via a pinion  35  and a segment gear  36 . Displacement of the table  30  in the X direction takes place by means of a stepper motor  37  and a spindle drive  38  (roughly outlined). The described design and the actuation of the table  30  are also known from U.S. Ser. No. 09/256,853, U.S. Pat. No. 6,095,066. A clamp  39  is disposed on the table  30 , fixing the workpiece  40 . A workpiece cutter  41  for cutting a buttonhole is customarily provided beside the needle bar  8  on the arm  4  above the table  30 . 
     As seen in FIGS. 3 to  5 , the chain stitch hook  14  is disposed in the hook bearing  13 ; a looper thread  45  is fed to the hook  14  through an opening  44  formed in the bottom  43  of the hook bearing  13  concentrically of the pivot axis  17 . Disposed on the base plate  2  above the hook bearing  13  and in the plane of the table  30  is a stitch plate  46  with a stitch hole  47 , through which passes the needle  12  with a needle thread  48 , the needle thread  48  being seized by the jogging hook  14  and a double thread chain stitch being formed in the workpiece  40 . 
     Further provided in the hook bearing  13  is a feeder  49 , feeding a gimp thread  50  to the workpiece  40  through the stitch hole  47 . This feeder  49  comprises a pivotal guide  51  for the gimp thread  50 . This guide  51  has a curved guide tube  52  which is mounted on a two-armed pivoted lever  53 . The lever  53  is mounted in a bearing  54  pivotally about a horizontal axis  55  which extends in the X direction; the bearing  54  is disposed in the hook bearing  13 . At the end, turned away from the guide tube  52 , of the pivoted lever  53 , a pivot drive  56  acts thereon, which is formed by a pneumatically actuated double action piston-cylinder drive articulated to the bottom  43  of the hook bearing  13 . A clamping device  57  is provided on the pivoted lever  53  in a manner allocated to guide tube  52 ; the clamping device  57  comprises a clamping surface  58 , which is formed on the guide tube  52 , a clamping jaw  59 , which cooperates therewith, and a clamping jaw drive  60  of linear action. The drive  60  is also formed by a pneumatically actuated double action piston-cylinder drive. 
     Provided on an inside wall  61  of the base plate  2 , which also carries the upper bearing  15  of the hook bearing  13 , is a gimp thread cutter  62 , which comprises scissors  63 , which are moved by means of a linear displacement drive  64  into a position of rest (seen in FIGS. 3 and 5) outside the hook bearing  13 , or which are moved into the wall  66  of the hook bearing  13  through an opening  65  thereof, into a position of work (seen in FIG. 4) located in the path of the gimp thread  50 . Also the displacement drive  64  is formed by a pneumatically actuated double action piston-cylinder drive. 
     The gimp thread  50  is supplied in the same way as the looper thread  45  through the opening  44  in the bottom  43  of the hook bearing  13  and piloted through a gimp thread guide  67  which is stationary in the hook bearing  13  and disposed on the path between the opening  44  and the guide tube  52 . The pivot drive  56  and the clamping jaw drive  60  are provided with compressed air via compressed air lines  68 ,  69 ,  70 ,  71 , which are flexible hose lines, leading through the opening  44  in the bottom  43  of the hook bearing  13 . Since the hook bearing  13  only performs a non-revolving pivotal motion, flexible plastic hoses are able to participate in this motion without being damaged. The displacement drive  64  is supplied with compressed air via compressed air lines  72 ,  73 . The scissors  63  are designed in known manner to perform a cutting motion upon advance into its position of cutting. A feed channel  74  for the gimp thread is formed in the stitch plate  46  and opens laterally into the stitch hole  47 ; it is located in the feed path of the guide  51 . 
     The cutter  41  is known partially from U.S. Ser. No. 09/063,965, U.S. Pat. No. 6,006,685. It comprises a lower knife  75 , which is located in the plane of the stitch plate  46  and is stationary in the base plate  2 , and a cutting block  76  located on the arm  4  beside the needle bar  8  and vertically above the knife  75 . The cutting block  76  comprises a carrier  77 , on which are disposed several knife abutments  78 ,  79 , only two of which are illustrated. The carrier  77  is rotatably mounted in a holder  80 , which is designed as a downwardly open bow, and it is drivable to rotate about an axis of rotation  82  by means of a rotary actuator  81  so that one knife abutment  78  and  79  at a time moves into a position allocated to the knife  75 . The holder  80  is non-rotatably, but axially displaceably arranged on a rod  80   a , the lower end of which rests on the carrier  77 . The rod  80   a  is displaceable in the Z direction, but is mounted non-rotatably in a bearing  83 . A lifting mechanism  84  of vertical action, i.e. which acts in the Z direction and is designed in the form of a pneumatically actuated double action piston-cylinder drive, acts on the upper end of the rod  80   a.  Further, a cutting drive arrangement  85  acts on the rod  80   a ; it comprises a lever  86  of substantially horizontal arrangement, one end  87  of which is articulated to the holder  80  and the other end of which is mounted in the arm  4  pivotally about a horizontal axis by means of a pivot bearing  88 . A roll  89  is attached to the lever  86  and can be engaged with a cam  91  formed on an operating lever. This operating lever  90  is mounted pivotally in a pivot bearing  92  in the arm  4 , pivoting about an axis that is parallel to the axis of the pivot bearing  88 . A cutting drive  93  in the form of a pneumatically actuated piston-cylinder drive acts on the end of the operating lever  90  that is opposite the pivot bearing  92 , the piston rod  94  of this drive  93  being articulated to the end of the operating lever  90  that is opposite the pivot bearing  92 . The cylinder  95  of the cutting drive is articulated by means of a bearing  96  in the arm  4 . The cam  91  on the operating lever  90  is formed in such a way that it engages with the roll  89  only after a certain motion of extraction of the cutting drive  93  and then forces the cutting drive  93  downwards and thus also the holder  80  together with the carrier  77  and the knife abutments  78 ,  79 , the downward knife abutment  78 , which is located above the cutting block  76 , bearing there-against. When the piston rod  94  is completely retracted into the cylinder  95 —as seen in FIG.  6 —then the holder  80  together with the knife abutments  78  can be lifted further upwards by means of the lifting mechanism  84  against the force of a spring  97  which is located between the holder  80  and the rod  80   a.  Only strokes in the order of magnitude of 5 mm and with a path of approximately 1 mm for the actual cutting job are performed at high forces by means of the cutting drive arrangement  85 . 
     The knife  75  has the shape of the longest possible incision to be carried out in a buttonhole, in particular in an eye type buttonhole. The knife abutments  78  only extend over the length along which an incision will really be performed in an eye type buttonhole. Wherever no knife abutment is available for the knife  75  when an incision is made, the workpiece  40  will yield laterally so that a shorter incision is made. 
     The feeding device  49  cooperates with the sewing tools, i.e. the needle  12  and the hook  14 , and with the cutter  41 , as follows: 
     The basis from which to proceed is a sewing operation illustrated in FIG. 3, in which zigzag stitches are made for the production of a buttonhole seam. The zigzagging configuration is produced exclusively by the needle jogging drive  23 . The gimp thread  50  is fed in a known manner into the buttonhole seam. In this case, the guide  51  together with the guide tube  52  is in its position of guidance, in which it is pivoted away from the stitch plate  46  and in which the gimp thread  50  is piloted through the opening  44 , the guide  67 , the guide tube  52  and the feed channel  74 , which discharges laterally into the stitch hole  47 , and in which the gimp thread  50  is fed out of the stitch hole  47  into the zigzag seam. The clamping device  57  is opened in this case. The cutter  62  is in its retracted position of rest so that the hook bearing  13  can be rotated together with the needle  12  freely about the pivot axis  17 , corresponding to the course of the seam that is to be produced. The double thread chain stitch seam is produced by cooperation of the needle  12  and the hook  14  in known manner. The course of the seam results from the displacement of the table  30  combined with the joint pivoting of the needle  12  and the hook bearing  13 . 
     Before the end of the seam is reached, the hook bearing  13  is in a position of rest, in which the opening  65  is located in front of the scissors  63 . Now the clamping jaw drive  60  is actuated such that the clamping jaw  59  is pressed against the clamping surface  58 , clamping the gimp thread  50 . Simultaneously the displacement drive  64  is actuated so that the scissors  63  are moved through the opening  65  into the hook bearing  13  where they cut the gimp thread  50  at a distance from the guide tube  52 . Immediately afterwards, the scissors  63  are moved out of the hook bearing by corresponding reverse actuation of the displacement drive  64 ; the gimp thread  50  remains clamped in the clamping device  57 . The moment when the gimp thread  50  is cut through is selected such that the part of the gimp thread that leads to the workpiece  40  is taken up entirely in the finished buttonhole seam, i.e. is used up. With the subsequent start of another gimp thread  50  zigzag seam, the end  75  of the gimp thread  50  which stands out from the guide tube  52  is automatically supplied to the feed channel  74  and thus to the stitch hole  47  by the pivot drive  56  being actuated in the way seen in FIG.  5 . In this way, the guide tube  52  moves as far as to the stitch plate  46  and pushes the free end  100  of the gimp thread  50  upwards through the feed channel  74  and the stitch hole  47 . During this feed motion, the gimp thread  50  is still clamped between the clamping jaw  59  and the clamping surface  58 . When another sewing job starts, the end  100  is clamped in the zigzag seam; the clamping arrest between the clamping jaw  59  and the clamping surface  58  is released, to which end the clamping jaw drive  60  is actuated counter to the clamping motion. Then the pivot drive  56  is again actuated in such a way that the guide tube  52  is pivoted back into its initial position illustrated in FIGS. 3 and 4. 
     FIG. 7 illustrates a jacket as a workpiece  40 , in which three different buttonholes are to be made, namely a lapel buttonhole A, two identical forepart buttonholes B and a sleeve buttonhole C. FIGS. 8,  9 ,  10  illustrate some buttonholes and the corresponding buttonhole seams only by way of example. FIG. 8 shows a simple button hole  101  without an eye, having a straight incision  102  and a rectangular zigzag seam  103 . FIG. 9 illustrates a buttonhole  104  with a so-called eye  105  and a straight incision  102  and a so-called eye type incision  106  in the eye  105 . In the vicinity of the eye  105 , the zigzag seam  107  extends on an arc of a circle. The buttonhole  108  of FIG. 10 corresponds to that of FIG. 9, a stitched transverse lock  109  being provided in addition to the zigzag seam  107  at the end opposite the eye  105 . Of course, there are lots of other forms of buttonhole seams, the illustration of which is however not necessary for the understanding of the invention. As described, the buttonholes  101 ,  104  and  108  are provided with different incisions  102 ,  102  and  106 . They are produced by varying triggering/activation of the cutter  41 . Of course, it is possible also to produce buttonholes without any incision as a decorative seam pattern by putting the cutter  41  out of operation in accordance with the program. 
     The sequence of the program can be seen from FIGS. 11 and 12. The sewing machine is provided with an operating and control unit  110 , into which to enter, via a keyboard, the parameters of a buttonhole  101 ,  104 ,  108 , for instance the length l thereof, and the decision of whether the buttonhole is to have an eye  105  and a gimp thread  50 . It is further entered whether the buttonhole is to have a straight incision  102  and an eye incision  106 . Further entries involve the question whether the buttonhole is to have a stitched transverse lock  109  and what will be the width a of this transverse lock. The width b of the stitches of the respective zigzag seams  103  and  107  can also be entered. The entered data can be checked by a display  112 . Further parameters of the buttonhole seams to be produced are programmable as well. 
     The freely selectable data are filed in working-storage sections  113  of the unit  110 , whereas data relevant to the machine are filed in the main storage  114 . 
     All the drive systems described inclusive of the drive system for the cutter  41  are triggered by the operating and control unit  110 . This is roughly outlined in FIG. 11 by correspondingly encircled reference numerals. FIG. 12 diagrammatically reflects the program entry PRG described above, use being made therein of the reference numerals introduced above. The type of the workpiece  40  is entered under PRG. This is followed by the entry of the buttonholes  101 ,  104 ,  108 , namely the lapel buttonhole A, the two forepart buttonholes B, B and the sleeve buttonhole C. Subsequently the respective lengths l are entered and then whether or not an eye  105  is to be sewn. In FIG. 12, the circle is marked with a diagonal cross for the corresponding feature. Then it is entered whether or not a gimp thread  50  is to be sewn in. Then it is decided whether a straight incision  102  or an eye incision  106  is to be made. Finally, it is decided whether a stitched transverse lock  109  is to be sewn and what will be the width. Finally, the width b of the zigzag seam  103  and  107  must still be entered.