Patent GB-1138200-A (GB)
Title: Sewing machines
Inventor: JOHNSON DAVID
IPC: D05B29/06
Filed: 1966-09-02
Abstract: 1,138,200. Sewing machines. WILLIAM BIRCH (ENGINEERS) Ltd. 25 July, 1967 [2 Sept., 1966], No. 39237/66. Heading D1G. In an overedge sewing machine a looper is mounted for reciprocating backwards and forwards movement in a looper frame which is pivotally mounted in a frame of the sewing machine and is driven with an oscillating motion to direct the looper alternately above and below the needle plate in its backwards and forwards movement. A lower shaft 10, which carries a pulley 15 coupled by a belt to a driving motor, is coupled by ratchet and pawl means to a feed wheel 55 carrying radial work-engaging spikes. Shaft 10 is coupled by a toothed belt 17 to an upper shaft 19 which carries at one end a handwheel 20 and at the other end a crank pin 26 engaged in a guideway 27 rigid with the needle bar 28 for reciprocating the latter. Shaft 19 is coupled by gears 34, 35 to a shaft 36 which is coupled by a toothed belt 43 to a shaft 45 journalled in a sub frame to provide for axial adjustment of shaft 45, the latter carrying a circular work-trimming blade 49. A presser bar 57 carries a presser foot 56 spring biased against feed wheel 55. A needle plate 58 has an L-shaped needle-passing slot 63 and a straight edge 64 adjacent feed wheel 55. The opposite edge has an initial portion 66 parallel with edge 64, a step 67 opposite the stitch-forming point, and a final inclined portion 68 adjoining the outlet of slot 63. A rectangular frame 71 has one side journalled on a horizontal stub shaft (72), and the other side journalled on a shaft 77 coupled by 2 to 1 gearing 84, 85 to shaft 10. A rod 70, slidably mounted in frame 71, carries a hooked looper 69 having a pivoted latch, and is rigid with a guideway 88 engaging a pin 87 on a disc 86 rigid with shaft 77. An extension 95 of frame 71 carries a pin 94 engaged in a cam groove formed in a disc 90 rigid with shaft 10. The two edges of two lengths of carpet to be united are placed one on top of the other and are trimmed in advance of the stitching point by the blade 49. When the needle descends through the work and commences to rise to throw a thread loop, frame 71 pivots downwardly and rod 70 advances to carry looper 69 through said loop. On retraction of rod 70, said loop is seized and extended by the hooked looper. When the needle rises, frame 71 pivots upwardly and rod 70 is advanced to project looper 69 above the work. The seized lower loop then moves along the looper stem. During the retraction of rod 70, the thread extending from the raised needle to the work is seized by the looper and extended as a loop which passes through the initially-seized loop as the latter is cast off the looper and over the edge of needle plate 59 at step 67. On the next advance of the lowered looper, the upper loop moves along the looper stem, and on retraction of the looper passes over the seized lower loop and is cast over the edge of needle plate 59. As stitching continues, the stitches pass along edge 68 for final release from slot 63. On completion of stitching, the carpet lengths are separated to form a flat seam as shown in Fig. 8. Depending on the amount of trimming, the sewn edges may either overlap, or abut or be separated from one another.