GB491719A - Improvements in or relating to sewing machines - Google Patents

Abstract

491,719. Sewing-machines. UNION SPECIAL MACHINE CO. March 5, 1937, No. 6520. Convention date, Sept. 19, 1936. [Class 112] A feed-off-.the-arm sewing-machine is provided with means for bringing the margins of fabric sections into upstanding contacting relationship, for laterally folding over both the margins flat upon one of the fabric sections and means for forming a line of seaming stitches through all three fabric thicknesses including a locking thread on the exposed face of the fabric. The general set-up of the machine is as disclosed in Specification 253, 620, [Class 112]. The feeding mechanism is as disclosed in Specification 491,720 and the presser foot is as disclosed in Specification 491,721. Needle mechanism. Three transversely spaced needles 68, 69, 70, Fig. 2, are carried by an arm 66, Fig. 2, pivoted within the worksupporting arm 7. The needles are curved concentrically with the pivot 67 of the arm 66. The arm 66 is swung on its pivot to actuate the needles by a link 71 connected to a bell-crank lever 72 having an arm 75 connected to the main shaft 12 by a pitman 76. Looper mechanism. A pair of loopers 78, 79, Fig. 2, are carried by an arm 80 swinging across the line of feed about a stud 81 carried on an arm 82. The loopers are swung by a pitman 86 connected by a ball joint to a crank on the countershaft 89 driven in unison with the main shaft by mitre gears. Trimming mechanism. A flexible arcuate trimming blade 127 is clamped to the projecting end of the sleeve 99 at the bottom of the head 5, Figs. 2 and 4. The sharp edge of the blade shears against the edge of a ledger blade 128 which overhangs the passage 107 in the presser foot. The blades are maintained in correct cutting relation by the tongue 130 of the blade 127 bearing on the top of the fixed blade 128. The sleeve 99 is oscillated to operate the blade 127 by a ball arm 131 at the top of the sleeve having a short link 132 connected to the looper-operating mechanism. Thread control. Threads for the loopers 78, 79 pass from the supply to usual disc tensioning devices mounted on the machine top, and through suitable guides to a rotary take-up 138, Fig. 4, forming part of the hand-wheel 139. The take up comprises two discs 140, 141 with an eccentrically disposed loop-engaging stud. The threads for the three needles 68, 69, 70 pass through similar tension discs and through suitable guides along the arm 7 to the needles. Operation. The fabric F is rounded upwardly above the rear end of the work arm 7 and the margins M, M<1> brought into upstanding relation. These edges are placed in the presser foot slot and the fabric advanced by the feed dogs to be turned, trimmed and stitched as shown in Figs. 19, 21, 27.