Sewing machine tape braking device
FIELD AND BACKGROUND OF THE INVENTION 
     This invention relates in general to sewing machines and in particular to a new and useful braking device for regulating the feed of a tape into the sewing machine which is operating on a garment to sew the tape thereon. 
     In a known brake device, as disclosed in U.S. Pat. No. 1,277,008 an elastic tape, coming from a supply roll disposed below the sewing table plane, is supplied traversing between the fixed guide member and the brake shoe to a deflecting guide arranged before the stitch formation point of the sewing machine between the folded-over waist edge of a garment such as a skirt. The brake shoe is mounted pivotably at a fixed guide member and is pressed by a spring against the tape abutting the fixed guide member. The brake force to be applied on the tape is adjustable with a set screw, to decelerate the tape at a controlled rate relative to the folded-over cloth plies at which the cloth feeders engage from above and from below, and thereby to retain it in a selected position relative to the folded-over cloth plies, so that the plies are gathered in different degree on certain sections, which, to facilitate handling, are generally marked. For every degree of gathering or ruffling the brake force must be changed. Exact adjustment, however, is not only very time consuming, but it is also almost impossible with known devices of this kind to repeatedly find adjustments exactly enough for different degrees of gathering or ruffling. 
     SUMMARY OF THE INVENTION 
     The invention provides a device providing for brake force adjustments for different degrees of gathering or ruffling which can be made quickly and effortlessly and are reproducible with high precision, just as quickly and effortlessly, in any desired alternating sequence. 
     The braking device of the invention thus designed permits smooth working, whereby a great increase in productivity and a substantial quality improvement are achieved. 
     Accordingly, it is an object of the invention to provide an improved brake device which includes a fixed guide over which material such as a tape is fed and a resilient member overlying the guide which is engageable with the resilient member to force it by a predetermined amount against the tape. 
     A further object of the invention is to provide a sewing machine which has a first feeding arrangement for feeding material and a braking device associated therewith for facilitating the feeding of a tape over the material being fed to a needle of the sewing machine by selected braking forces so as to provide distinct sewing results. 
     A further object of the invention is to provide a braking device and a sewing machine which are simple in design, rugged in construction and economical to manufacture. 
     The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is an end elevation of a simplified representation of a sewing machine fitted in a frame, with top and bottom transport, with an inventive new brake device constructed in accordance with the invention; 
     FIG. 2 is a side elevational view with the brake device; and 
     FIG. 3 is a bottom plan view of the brake device from below. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings in particular the invention embodied therein comprises a braking device generally designated 10 which is used for advancing a tape material ST into association with other material W being fed to the sewing machine over a table 1 using a first sewing machine feeding arrangement or apparatus 5 which feeds the material past a reciprocating needle 7. In accordance with the invention the tape ST is fed over a fixed guide member 12 and up through a slot 14 of the table into association with the material W which is fed to the reciprocating needle 7. In accordance with the invention a resilient member in the form of a leaf spring 15 overlies or underlies the fixed guide member 12 onto which the tape material is fed with means such as a multiple step cam plate 20 positioned in contact with the leaf spring 15 so as to provide a force acting on the spring member 15 which provides a selected braking force to the tape which is being fed. In an opening of a table top 1 of a frame 2, a sewing machine 3 is inserted, which in addition to the usual lower cloth feed 4, executing a rectangular feeding movements, comprises an upper cloth feed system 5. The sliding paths of the lower and upper cloth feeds are adjustable independently of each other. The thread carrying needle 7 of the sewing machine 3, secured on the needle bar 6, cooperates with a shuttle 8 arranged in the cloth support plate of the sewing machine 3, as known, for seam formation. 
     Screwed to the underside of the table top 1 is a brake device 10, arranged on a support plate 9, for a tape ST to be supplied to the stitch-formation point of the sewing machine 3. The tape ST, coming from a supply roll on the frame 2, is passed between a guide member 12 fastened on spacers 11 at the support plate 9 and a movable brake shoe 13 and through a slanting slot 14 in the table top 1, to the stitch-formation point. 
     To apply a brake force on the brake shoe 13 there is used in the embodiment a leaf spring 15, one end of which rests on an eccentric stud 16 in bearing brackets 17 of the support plate 9, and whose other end engages at the brake shoe 13 with interposition of a rounded member or rolling body 18. This end of the leaf spring is lightly bent semicircularly and forms a running surface for the rolling body 18. The brake shoe 13 is arranged displaceably on spaced apart shank screws 19 in spacers 11 of the support plate 9 relative to the fixed guide member 12. 
     To vary the brake force, the tension of the leaf spring 15 is variable by a multi-step cam plate 20, which is mounted on a short shaft 21 in the forked vertical leg 22 of an angle piece 24 secured on the support plate 9 with screws 23. On its free end a turning knob 25 is secured. On the periphery the cam plate 20 has flat surfaces 26 to 31, which are arranged at different distances from the shaft 21 and form the various steps of the cam plate 20. Each step corresponds to a different brake force value. The basic adjustment is made at the eccentric stud 16. In the operating position, the particular surface 26 to 31 is parallel to its abutment surface on the leaf spring 15. This eliminates the need for an additional locking means to secure the various operating positions of the cam plate 20. 
     A pneumatic short stroke cylinder 32 attached to the support plate 9 serves to lift the brake shoe 13 off the tape ST or respectively off the fixed guide member 12 counter to the action of the leaf spring 15. The short stroke cylinder 32 can be driven via a 3/2-way valve 33, whose working connection A is connected by a conduit 34 to the short stroke cylinder 32 and is vented via R in the neutral position. 
     The pump P of the 3/2-way valve 33 is connected via a conduit 35 to a compressed air source 36. 
     Operation: 
     The assumption is that a workpiece W needed for example in upholstering, having sections or parts of different degrees of ruffling or gathering and also having sections without gathering, is to be sewn onto the tape ST supplied from below. 
     Before sewing is started, the upper feed device 5 is lifted and the multiple way valve 33 is actuated, so that compressed air is supplied to the short stroke cylinder 32 from the compressed air source 36 via line 35, connections P and A, and line 34, the working piston of the cylinder 32 raising the brake shoe 13 counter to the action of leaf spring 15. For reintroducing a tape end into the brake device, the brake shoe 13 could also be adapted to be turned aside. 
     After the brake shoe 13 has been lifted, the tape ST can then be pulled forward unhindered and tension-free to under the raised upper feed device 5, and the multiple way valve 33 can be switched off again. The short stroke cylinder 32 is vented via line 34 and the connections A and P. By a spring in the cylinder housing the working piston of cylinder 32 is moved to its inactive position. 
     By the leaf spring 15 the brake shoe 13 presses the tape ST against the fixed guide member 12. The magnitude of the brake force to be supplied depends on what degree of gathering or ruffling of the workpiece W on the tape ST likewise inserted under the upper feed device 5 is to have on certain, previously marked sections. This depends on which of the surfaces 26 to 31 disposed at different distance from the axis of rotation 21 applies against the leaf spring 15. Moreover, it is possible to give the upper cloth feed greater forward movements than the lower, to influence the degree of gathering or ruffling. 
     The adjustment for the following seam section having been selected at the turning knob 25, the upper feed device 5 is lowered and the sewing machine 3 is turned on. 
     During sewing, the tape ST is held back by the tape brake 10, so that the work W is pushed together by the upper feed device 5, that is, gathered or ruffled, and is fixed in this state on tape ST by a seam. To adjust a different degree of gathering or ruffling, it suffices to turn the multi-step cam plate 20 by means of knob 25, in order that the surface 26 to 31 corresponding to the desired degree of gathering comes to abut on the leaf spring 15. In many cases the sewing machine need not even be stopped. If the work W is to be sewn onto the tape ST without gathering or ruffling, it suffices to actuate the multiple way valve 33 in order to take the brake force away from the brake shoe 13. On the assumption that the upper and lower cloth feed devices 4 and 5 are adjusted for synchronous forward movement, the work W and tape ST are sewn together lying smoothly one on the other. 
     To mark the operating position of the individual surfaces 26 to 31, markings may be provided on the knob, so that there will be no problem in coming back to the angular position of knob 25 corresponding to a specific degree of gathering on the work W. 
     While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.