GB1110639A - Built-in automatic buttonholing device - Google Patents

Abstract

1,110,639. Sewing machines. SINGER CO. 4 April, 1967 [7 April, 1966], No. 15253/67. Heading D1G. A sewing machine, adapted for sewing buttonholes, comprises a flat work-supporting bed a standard, a bracket arm supported by the standard and terminating in a sewing head, a rock shaft journalled in the bracket arm for oscillation and for endwise movement, a unit detachably secured to the rock shaft externally of the bracket arm and including the work-engaging foot overlying the bed, and means operatively connected within the arm to the rock shaft for imparting oscillatory and endwise movements thereto in a predetermined sequence, whereby the work-engaging foot is moved in a closed path parallel to the bed. The bracket arm 14 of a zig zag sewing machine journals a rock shaft 100 detachably carrying an external crank arm 72. Pivoted at 70 to the lower end of the latter are resepctive lower and upper arms 54 and 56. A screwed spindle 92 passing through arms 54, 56 supports a spring 94 compressed by a nut 98 on spindle 92. An apertured, work-engaging plate 82, pivoted at 80 to the free end of arm 56, co-operates with the apertured, work-engaging free end of arm 54, the aligned apertures being surrounded by respective cork pads 86, and accommodating the usual presser foot 35. Arms 132, upstanding from shaft 100 within bracket arm 14, have slotted upper ends engaging pins 138 projecting from a plate 144 slidably supported by a fixed bracket 146. Plate 144 is apertured to receive a button hole template 154 formed with an endless buttonhole-shaped groove (156) and a parallel endless rack (158). A depending portion 159 of bracket 146 supports an upstanding pin 164, the reduced upper end 174 of whichengages groove (156), and which journals a ratchet wheel 228 rigid with a pinion 230 meshing with rack (158). A plate 178, journalled on pin 164, carries a pivoted pawl 184 biassed by a spring 186 against ratchet wheel 228. A spring 198 biasses the latter counterclockwise to engage one end of a slot 182, formed therein, with a pin 190 rigid with one end of a bar 188, the other end of which carries a pin 192 slidable in a slot 194 formed in a depending .portion 167 of bracket 146. Bar 188 co-operates with an eccentric cam 196 on the arm shaft 18 for turning plate 178 and ratchet wheel 228 clockwise against the bias of spring 198. A plate 200, journalled on pin 164, carries a pivoted check pawl 224 biased by a spring 226 against ratchet wheel 228. The periphery 202 of plate 200 is so shaped as to disengage pawl 184 from ratchet wheel 228 before the end of its stroke. A radial arm 204 on plate 200 is connected by a link 206 to a stud 210 slidable, by means of a handle 222, in a slot 212 provided in an extension arm 153 of bracket 146, to turn plate 200 for varying the operative stroke of pawl 184. A bar 238 is biased by a spring 254 to position a stud, carried at one end, at the right hand end of a slot 180 formed in plate 178, and to position a stud 224, carried at the other end, at the right hand end of a slot 246 formed in an extension arm 151 of bracket 146. If stud 244 is moved by a handle 252 to the left hand end of slot 246, the stud at the other end of bar 238 co-acts with the left hand end of slot 180 to turn plate 178 sufficiently to render pin 190 inoperative in slot 182.