Abstract:
In a method of operating a sewing machine for joining a jacket part ( 38 ) to a sleeve part ( 39 ), a sewing machine is employed, which has an operating and control unit. The desired stitch length and the length (la 1  to ld 1 ) of sections (a 1  to d 1 ) of the jacket part ( 38 ) and the length (la 2  to ld 2 ) of the sections (a 2  to d 2 ) of the sleeve part ( 39 ) that are allocated to the sections (a 1  to d 1 ) are fed into the operating and control unit. The required control pulses for the necessary feed drives are determined therefrom for each section (a 1 /a 2  to d 1 /d 2 ).

Description:
REFERENCE TO RELATED APPLICATIONS 
     The present application is the national stage under 35 U.S.C. §371 of international application PCT/EP00/03151, filed Apr. 8, 2000 which designated the United States, and which application was not published in the English language. 
    
    
     The invention relates to a method according to the preamble of claim  1 . 
     BACKGROUND OF THE INVENTION 
     A method of the generic type is known from EP 0 124 211 B2. In this case, a workpiece is shifted between two adjacent stitches by a greater length than another workpiece. To this end, control data of a sequence or a profile of varying feeds and advances is given by a control unit in dependence on a count of a stitch counter. A similar method is known from the PFAFF leaflet 3834-4/11. 
     DE 34 90 775 C2 (corresponding to WO 86/02673) teaches a fundamentally similar apparatus. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of the invention to embody a method of the generic type such that programming the sewing machine can be carried out very easily and without too much time needed. 
     According to the invention, this object is attained by the features of the characterizing part of claim  1 . The gist of the invention resides in that the lengths of sections that have been determined by the modeler are directly fed in. No stitch counts are fed in for certain stitch lengths, but the desired stitch length in addition to the length of the individual sections. Based thereon, the computer determines gathering values, which are displayed on the display unit of the operating and control system, thus being visible and verifiable for the operator. If necessary, the gathering values may be modified by the operator if the sewing pattern does not correspond to the predetermined values. The computer automatically considers such a modification of the gathering values in correspondingly triggering the feeder-actuating stepper motors. A modification of the desired stitch length does not affect the values determined for the individual sections. Correspondingly, the operator is free to suit the stitch length to fabric quality or to select them in accordance with fabric quality. Corresponding to the given stitch length, the computer automatically determines the triggering data for the stepper motors. 
     The input, according to claim  2 , of graduation values given by the modeler for the sections of a basic garment size enables values to be prepared automatically for the workpiece sections of other garment sizes, there being no need for any time-consuming input of values for workpieces of other garment sizes. 
     As a result of the input of so-called fabric correction values according to claim  3 , the effect of the advance motion of the respective feeder on the workpiece it transports is taken into account. This is important in particular for very smooth fabrics, in which case slip will occur between the fabrics and the feeder. It may be equally important for very rigid or thick fabrics. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     Details of the invention will become apparent from the ensuing description of an exemplary embodiment, taken in conjunction with the drawing, in which: 
     FIG. 1 is a strongly diagrammatic illustration of a lateral view of a sewing machine that is suitable for the method according to the invention; 
     FIG. 2 is a diagrammatic view of the fabric feeder arrangement of the sewing machine in accordance with the arrow II of FIG. 1; 
     FIG. 3 is a diagrammatic illustration of a sleeve part that is to be sewn to a jacket part; 
     FIG. 4 is a diagrammatic view of a data record in an abstracted illustration that appears on the display of the operating and control unit; and 
     FIG. 5 is a concrete example of a data record appearing on the display. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a sewing machine  1  which conventionally comprises an upper arm  2 , a vertical standard  3  and a lower housing that is customarily called the base plate  4 . The base plate  4  has an upward post  4   a , which is why a sewing machine of this type is called a post-bed sewing machine. An arm shaft  5  is rotatably mounted in the arm  2 ; on its end that projects from the arm  2 , it is provided with a balance wheel  6 . Actuation of the arm shaft  5  and thus of the substantial basic units of the sewing machine  1  takes place by means of an electric driving motor  7  via a belt drive  8 . In the vicinity of the balance wheel  6 , an incremental transmitter, which is usually called a position transmitter  9 , is mounted on the arm shaft  5 . 
     Connected to the arm shaft  5  on the end opposite the balance wheel  6  is a crank drive  10 , by means of which a needle bar  11  that is vertically mounted in the arm  2  is drivable to reciprocate up and down. At its lower end, the needle bar  11  is provided with a needle  12 . Below the needle bar  11 , a two-thread lock stitch hook  13  is rotatably drivably mounted in the base plate  4 . Rotary actuation is derived from the arm shaft  5  by way of a belt drive  14  and shafts  15 ,  16  so that synchronous motions of the needle  12  and hook  13  are obtained, which combine to form the sewing implements. Of course, the hook  13  rotates at twice the speed of the arm shaft  5 . The needle thread is customarily supplied to the needle  12 . The hook  13  is customarily equipped with a hook thread supply. The workpieces  38 ,  39  that are to be sewn up, are led over a stitch plate  17 , which finishes the upper side of the base plate  4  and through which the needle  12  reaches into the vicinity of the hook  13 . 
     A fabric feeder arrangement  18  is provided by the side of the needle bar  11 , having an upper feeder  19  and a lower feeder  20 , which are diagrammatically shown in FIG.  2 . 
     The upper feeder  19  comprises a driving pulley  21  which is lodged in the arm  2  and which a lower deflection pulley  22  is allocated to; the deflection pulley  22  is flexibly mounted on the arm  2  by way of a lever  23 . An upper feed belt  24  is led along the driving pulley  21  and the deflection pulley  22  and additionally along deflection rolls  25 . The driving pulley  21  is actuated by means of an upper stepper motor  26  that is mounted in the arm  2 . 
     The lower feeder  20  comprises a driving pulley  27  lodged in the base plate  4 , with a deflection pulley  28  allocated thereto that is equally lodged in the base plate  4 . A lower feed belt  29  is led over the driving pulley  27  and the deflection pulley  28 . Actuation of the driving pulley  27  takes place by means of a lower stepper motor  30  that is disposed in the base plate  4 . The feed belts  24  and  29  adjoin each other approximately in the plane of the stitch plate  17 . A fabric feeder arrangement of this type is known for instance from DE 90 11 178 U (corresponding to U.S. Pat. No. 5,249,540). Instead of the fabric feeder arrangement shown, an arrangement may be used in which two feed wheels are in direct engagement with the workpieces  38 ,  39  that are to be sewn up. Fabric feeder arrangements of this type are known for instance from DE 35 46 541 C2 (corresponding to U.S. Pat. No. 4,671,197). 
     An operating and control unit  31  is mounted on the sewing machine  1 , comprising an operating equipment  32  and a control equipment  33 , which are interconnected electrically. The operating equipment  32  comprises a display unit  34  and an input keyboard  35 . A data line  36  is provided for the supply of data for instance from a modeler&#39;s PC. Furthermore, data may be fed in via a RAM memory card  37 . 
     The control equipment  33  comprises a computer (not shown) and an input that comes from the operating equipment  32  and another input coming from the position transmitter  9 . 
     As seen in FIG. 3, two workpieces  38 ,  39  are to be joined, the first workpiece  38  being a jacket part with an armhole  40  and the second workpiece  39  being a sleeve part. Around the armhole  40 , the first workpiece  38  is divided into sections, four sections of which are designated by a 1  to d 1  by way of example, with the number of sections being distinctly higher in practice. Sections a 2  to d 2 , which are allocated to the sections a 1  to d 1 , are provided on the second workpiece  39 , the second workpiece  39  and the first workpiece  38  being sewn up in such a way that the associated sections a 1 -a 2  to d 1 -d 2  are sewn up. The individual sections a 1  to d 1  have a length la 1  to ld 1 . The sections a 2  to d 2  have a length la 2  to  1 d 2 . The excess widths resulting from the difference of the lengths la 2  and la 1  must be arranged in a uniform gathering when the individual sections a 1  and a 2  to d 1  and d 2  are sewn up. 
     As seen in FIGS. 4 and 5, the lengths la 1 , la 2  etc. of the seam sections a 1 /a 2 , b 1 /b 2  etc. in millimeters are fed in—as mentioned—via the data line  36  from the modeler&#39;s PC and/or via the RAM memory card  37  and/or via the input keyboard  35 . In this case, FIG. 4 lists the general designations and FIG. 5 the numerical data of an exemplary embodiment. The input involves a basic garment size  50 . From the lengths la 1 -la 2 , which are allocated to each other, the computer of the operating and control unit  31  automatically determines the associated gathering value KW. This gathering value KW is a non-dimensional characteristic number ranging between 0.0 and 15.0 in steps of 0.5. Allocated to each characteristic number is a feed increase value [mm], by which the upper feeder  19  must additionally transport the second workpiece  39 , namely the sleeve part, as opposed to the lower feeder  20  which transports the workpiece  38 . This gathering value KW is related to a basic stitch length s that corresponds to the advance of the first workpiece  38 . 
     Furthermore, a so-called graduation value GR is fed in. Such a graduation value specifies a length [mm] by which the length la 1  to Id 1  of the section a 1  to d 1  of the armhole  40  increases or decreases from one garment size to the next greater or smaller garment size. The graduation value gives the section increases from the basic size  50  to the next garment size  52 ,  54  etc. In this way, it is possible, based on the graduation values, to compute the lengths la 1  to Id 1  on the one hand and correspondingly la 2  to  1 d 2  on the other for further garment sizes, such as  46 ,  48 ,  52 ,  54 ,  58 ,  60 ,  62 . Upon preparation of a model, the graduation value GR is determined and given by the modeler, based on the pattern. For optically identical gatherings of sewn up workpieces  38 ,  39  to be obtained along identical sections a 2  to d 2  of varying garment sizes, the associated sections a 1  and a 2  etc. are enlarged proportionally. After input of all the garment-size- 50  graduation values GR given for the individual sections a 1 /a 2  etc., the computer automatically computes all the remaining sections la 1 , la 2  etc. for all the garment sizes involved in a sewing job. 
     Furthermore, the desired stitch length s [mm] is fed in, by which the workpieces  38 ,  39  are to be sewn up. In dependence on the lengths la 1  to Id 1  and the fed-in stitch length s and in consideration of further machine-specific parameters, the computer calculates the triggering values for the stepper motors  26 ,  30  and the number of stitches required for each section a 1  to d 1 . The machine-specific parameters take into account that the sewing machine  1  is not equipped with a needle  12  that co-vibrates in the feed direction  41 , but only has a needle  12  of reciprocating up and down motion so that the feeders  19  and  20  may be actuated only when the needle  12  does not stitch into the workpieces  38 ,  39 . The feeders  19 ,  20  may only be actuated in the case of a certain area of infinitesimal rotation of the arm shaft  5 . The unit  31  receives corresponding information from the position transmitter  9 , from which it also receives a signal for each stitch that is made so that stitch counting takes place for each section a 1  to d 1 . 
     In addition, a so-called fabric correction value f can be fed in as a non-dimensional figure, by means of which to consider the effect of the feed motion of the feeders  19 ,  20  on the advance of the workpieces  38 ,  39 . In the case of a very smooth fabric for instance, slip will occur between the respective workpiece  38  and  39  and the corresponding feeder  19  and  20 . By means of this fabric correction value, the feed per stitch of the feeders  19 ,  20  is as a rule modified in order for the desired stitch length to be obtained. The fabric correction value ranges between 1.0 and 1.2. 
     The subsequent sewing job then takes place fully automatically after the sewing machine has been set into operation, in which case, once the first section a 1 /a 2  has been sewn, transition to the values given and determined for the sewing job of the second section b 1 /b 2  takes place automatically.