Patent GB-563921-A (GB)
Title: String inserting mechanism for sewing machines
IPC: D05B23/00
Filed: 1943-05-18
Abstract: 563,921. Sewing machines. FAIRWEATHER, W. C. (Singer Manufacturing Co.). May 18, 1943, No. 7882. [Class 112] Means to lay a string 114 within a hem 111 (see Fig. 8) of a piece of material in a hem-folding and stitching operation in the production of bags equipped with draw - strings, comprises a string-clamp 88 oscillated by an arm 77 within a folder 104, which produces the hem 111, in opposition to work being fed forward by a four-motion feeddog 49. The needlebar 19, Fig. 2, is driven from a main shaft 14 and an upper rock-shaft 15 through a crank-arm 16 and link 18. The presserbar 21 is held on the work during sewing by a spring 23. The manually - operated presser - lifting lever 28, thread-controller rock - shaft 27 and feed-bar 30 mechanism are described in Specification 473,585. A rock-shaft 33 is oscillated, carrying the head 35 to move the feed-bar 30 up- and - down, a coil spring 38 pressing the head downwards and includes a lost-motion connection 37, 40. Driving means for the presser-bar act through a link 41 (see Specification 473,585). A rockshaft 57, which oscillates the arm 77, is driven by an eccentric 53 and pitman 59 through a curved crank-arm 58. The connecting guide head 61 is slotted to receive and slide upon the arm 58 to a new position if it is desired to vary the amplitude of oscillation of the arm 58. A chain 66, attached to a pedal or knee-shift, and links 62, 63, 64 are used against a spring 67, to adjust the position of the head 61. An adjustable stub arm 79 has a rigid pin 81 which pivotally carries a divided collar 83 secured to an L-ahaped platform 85 having a pair of ears 86. A jaw 88 pivoted on a pin 87, forms, with the platform 85, a string clamp or auxiliary work-feeding member with teeth on the forward portion of a spring metal nose-piece 92. The teeth permit the string to be pulled through the string clamp in a forward direction and prevent retrograde motion. A spring 98 forces the divided collar 83 to press the string- clamp towards the cloth plate 52. The string- clamp may be lifted manually by means of a lever 102 against the spring 98. As the crankarm 58 is concentric with the shaft 14 whenever the crank-arm is in its raised position the string-clamp will always be brought forward towards the feed-foot 29 to the same point. An adjustable edge folder 104 is secured to the cloth-plate 52, the clamp reciprocating within the folder. The work-piece fed along by the dogs 29, 49 is guided by a finger acting on the outer edge of the fold. The foot 29 engages the fold 107 and the presser-foot 22, which is provided with an edge-guide 108 and needleaperture 109 engages the edge 110. The edge portion 110 is elevated by a wing portion 112, projecting from the edge-guide 108, so that the string-clamp, may reciprocate beneath that portion of the material. The eccentric 53 is timed so that the string-clamp and the feedfoot 29 swing towards and away from each other. The foot 29 is lifted off the work whenever the clamp is in its forward position to which it carries a supply of draw-string. To vary the amount of string deposited within the hem pocket, the operator adjusts the stroke, of the arm 77 by shifting the arm 64. Specification 352,848 also is referred to.