Patent GB-1149350-A (GB)
Title: A device for the changing of the stitch width of a zig-zag stitch produced in a sewing machine
IPC: D05B3/08
Filed: 1967-01-19
Abstract: 1,149,350. Sewing machines. ELITEXZAVODY TESTILNIHO STROJIRENSTVI GENERALNI REDITELSTVI. 19 Jan., 1967 [19 Jan., 1966], No. 2859/67. Heading D1G. zig zag sewing machine comprises means for adjusting the stitch width, rotary means for controlling rotation of the stitch-forming means, and means for controlling said adjusting means, the arrangement being such that after rotation of the stitch-forming means through a predetermined angle, said rotary means influence said controlling means for effecting required change of stitch width. The arrangement is incorporated in the machine described in Specification 1120988 for sewing eyelet-ended buttonholes completed by transverse reinforcing stitches which are covered by barring stitches disposed at right angles to the axis of the buttonhole, and is adapted to reduce the width of the barring stitches. Gears 110, 111, associated with the needle bar 234 and looptaker respectively, mesh with respective gear segments 108, 109 on a shaft 105 coupled by a crank 104 and link 102 to one arm of a two-armed lever 98 pivoted at 99. A follower 96, carried by said arm, engages a cam groove 236 formed in a driven gear 19 journalled on a shaft 20, for rotating the stitch-forming means during the sewing of the eyelet end of the buttonhole. The other arm of lever 98 has a follower end 155 cooperating with a rotary cam 151 for turning the stitch-forming means through 90 degrees to produce the barring stitches. Shaft 20, which is arranged to actuate the needle bar and looptaker, is driven via gears 89, 90 from a shaft 49. A cam 201 on the latter is embraced by the forked end 202 of a lever 203 pivoted intermediately at 205 on a block 206 slidable in a groove 207 formed in an arm 208 rigid with a pivot 209 journalled at 210 in the machine frame. A lug 211, rigid with arm 208, is biased by a spring 216 against a cam 212 turnable by handle 215 for varying the inclination of arm 208 and groove 207. the other end of lever 203 is pivoted at 217 to an arm 218 rigid with a cylinder 219 journalled at 220 in the machine frame. A rod 222, slidable diametrically in cylinder 219, has a forked end 223 pivoted on pins 226 projecting diametrically from a collar 225 pivoted, but fixed axially, on needle bar 234 which is supported at its upper end in a universal bearing 235. A sleeve 227 pivoted, but fixed axially, on needle bar 234 below collar 225, carries at its lower. end a block 228 formed on opposed faces with inclined grooves 229 engaged by respective pins 230 carried by lugs 231 depending from gear 110. The arrangement is such that on rotation of shaft 49 the needle bar receives transverse swinging movement, the amplitude of which may be adjusted by turning cam 212. An arm 301, rigid with pivot 209, is pivoted to one end of a bar 303, the other end of which is formed with a slot 305 engaged by a pin 309 upstanding from a bracket 307 secured adjustably on the upper end of shaft 105 by a screw 310. A pin 308 projecting horizontally from bracket 307 is arranged, when shaft 105 is turned for producing the barring stitches, to engage a vertical surface 306 on bar 303 for displacing the latter to change the inclination of bar 208, and thereby reduce the stitch width.