Skip-Stitch Mechanism for Household Sewing Machines

摘要

1,195,508. Sewing machines. SINGER CO. 23 Sept, 1968 [29 Sept., 1967], No. 45093/68. Heading DIG. In a zig zag sewing machine having respective drive means for imparting to the needle bar endwise reciprocating movements and lateral jogging movements, skip stitching is effected by disconnecting the needle bar from the drive means producing endwise movements. In Figs. 3 and 6 a needle bar 22 is mounted in a first universal bearing 29 carried by the machine frame and in a second universal bearing 27 carried by a needle bar gate 26 pivotally mounted on a fixed vertical pin 28. Lateral movements are imparted to gate 26 by a bar 30 pivoted at one end thereto and carrying at its other end a pivoted plate 32 selectively engagable with cam follows 44, 46, adapted for selective engagement with rotary cams 47. A block 82, rigid with needle bar 22, carries a pin 120 slidable in a slot 118 in a fixed bracket 116 to prevent rotation of the needle bar. Lugs 84 on block 82 carry a pin 86 pivoting a double-armed lever, the upper arm 90 of which is biased by a spring 96 to engaga the hooked end 94 of the lower arm 92 with a plate 78 on a sleeve 80 which is slidable on needle bar 22 and is coupled by a link and crank to the machine arm shaft, whereby needle bar 22 reciprocates with sleeve 80. A shaft 106, journalled in the machine frame, carries a radial arm 108 rigid with a blade 110, the arrangement being such that when shaft 106 is rotated clockwise to engage blade 110 with a surface 102 on gate 26, arm 90 on its next ascent engages blade 110 and is thereby turned counterclockwise to uncouple end 94 from plate 78, while a hooked end 100 of arm 90 engages a notch 112 in blade 110. Needle bar 22 is thereby held in the raised position while sleeve 80 reciprocates freely. Shaft 106 carries a radial pin 124 which is connected to a spring 122 for biasing shaft 106 clockwise to the needle bar-disengaging position, and which passes through a slot 136 in one arm of a bell crank lever 140 pivoted at 142 to the machine frame. The other arm of lever 140 is connected by a pivotal link 150 to one end of an arm 160, the other end of which is pivoted at 164 intermediately on a cranked arm 166 pivoted at one end at 170 to the machine frame and having at its other end an upstanding lug 176. A spring arm 182, rigid with arm 166, passes through a slot 184 in the front panel 20 of the machine upper arm 14. When arm. 182 engages a notch PSS at the left hand end of slot 184, a follower finger 162, rigid with arm 160, co-operates with a skip-stitch rotary cam 186 having fourequally-spaced lobes, whereby, when finger 162 engages a trough of cam 186, spring 122 lowers blade 110 to the needle bar-disengaging position, while when finger 162 engages a lobe, blade 110 is raised for a sufficient time to produce a single stitch. When arm 182 is engaged with a middle notch NS, finger 162 is disengaged from cam 186 but no movement is imparted to link 150, whereby blade 110 remains lowered in the non-stitching position. When arm 182 engages a right hand notch CS, lug 176 engages arm 160 to shaft link 150 rightwards for raising blade 110, whereby stitching proceeds uninterruptedly. Fig. 12 shows an arrangement in which, when arm 182 engages notch NS, a lug (420) depending from arm 160 abuts a crank (418) connected by a linkage to a handle (404), actuation of which thereby serves to shift link 150 for effecting stitching. In Figs. 7 and 10 a needle bar 218 is slidable in spaced ears 216 on a gate 208 having spaced ears 210 pivoted on a fixed vertical pin 212. Lateral movements are imparted to gate 208 by a bar 236 pivoted thereto at one end and co-operating at its other end with rotary pattern cams 248. A block 256, rigid with needle bar 218, carries a pin 258 on which is pivoted one end of a flat, depending latch bar 260 biased counterclockwise by a spring 268 to engage a notch 262 therein with a pin 225 on a sleeve 224 which is slidable on needle bar 218 and is connected by a link and crank to the machine arm shaft. A shaft 314, journalled in the machine frame, is rigid with a depending arm 316 carrying a pin 318 which, when shaft 314 is turned counter-clockwise, engages bar 260 for unlatching notch 262 from pin 225, and which then enters a notch 264 in bar 260. When shaft 314 is thereafter turned clockwise, pin 225 is engaged by a tail 270 on bar 260, and is led thereby into notch 225. An arm 282 is pivoted on a fixed pin 286 within the machine arm 198, and passes through a slot (290) in the front panel of the latter. Also pivoted on pin 286 is a bell crank lever 294 carrying at its respective ends upstanding pins 300, 302. A cranked lever 276 is pivoted intermediately at 280 on arm 282, is provided at one end with a follower pin 324, and is formed at the other end with a slot 306 engaged by an upstanding pin 310 on a block 312 rigid with shaft 314. A spring 322 biases lever 276 counterclockwise. When a spring finger 292, carried by arm 282, engages a notch PSS at the right hand end of slot (290), pin 324 co-operates with a rotary skip-stitch cam 274 having four long lobes 273 and four short troughs 275. When pin 324 engages a lobe 273, slot 306 engages pin 310 to turn shaft 314 clockwise for uncoupling needle bar 218. When pin 324 enters a trough 275, needle bar 218 is coupled to block 224 for sufficiently long to produce one stitch. When finger 292 engages a central notch CS, pin 324 is disengaged from cam 274 and the needle bar remains coupled. When finger 292 engages a left hand notch NS, arm 282 engages pin 302 to turn lever 294 clockwise, where'by pin 300 engages a finger 308 on arm 304 to turn the latter clockwise and thereby shaft 314 counterclockwise for permanently uncoupling needle bar 218.