Patent GB-950244-A (GB)
Title: Improvements in and relating to zigzag sewing machines
Inventor: ERIKSSON ALLAN HERMAN
IPC: D05B19/00
Filed: 1962-06-26
Abstract: 950,244. Sewing machines. HUSQVARNA VAPENFABRIKS A. B. June 26,1962, No. 24574/62. Heading D1G. In a zig-zag sewing machine the respective means for controlling the stitch width, stitch position and work feed may be coupled together for manipulation by a setting member to produce buttonhole stitching, the feed-controlling means has different movements for controlling the magnitude and direction of feed respectively, and the setting member operates only to change the direction of feed, the magnitude of feed being variable manually at any time during buttonhole stitching. The swinging gate 9 for the needle bar 10 has pivoted thereto one end of a bar 37,the other end of which is biased by a spring 38 against a cam follower arm 35 pivoted at 34 to one arm of a bell crank lever 45 pivoted at 44 to the machine frame. Arm 35 co-operates with a cam 31, driven by gearing 33 from the arm shaft 12, for oscillating gate 9. The position of engagement of bar 37 with arm 35, for determining the stitch width, is controlled by a link 43 connecting bar 37 to a pivoted follower arm 42 spring-biased into engagement with a cam 39 fast on a shaft 40 turnable by means of a knob 41. Lever 45 may be turned counterclockwise from a mid position, for shifting the stitch position leftwards, by the co-operation of its other arm with a cam 51 fast on a shaft 52 turnable by means of a knob. The feed dog 13 is carried by a feed advance shaft 14 to which is pivoted one end of a pitman 15, the other end of which is forked to embrace a cam 16 on shaft 12. A block 17, pivoted to pitman 15, is slidable in a pivoted guide 18, the inclination of which determines the magnitude and direction of work feed. A spring 30, associated with guide 18, biases a lug 29 on the latter against one end of a slidable bar 27, whereby a pin 26 on a leg 67 rigid with bar 27 is engaged with the right hand side of a V-shaped peripheral groove 23 formed in a pivoted cylinder 21 turnable by means of a knob 22 for thereby varying the magnitude of forward feed. The other end of bar 27 is constituted by a push button 28, manipulation of which shifts pin 26 to the left hand side of slot 23 for reversing the feed. For buttonhole stitching, knob 41 may be coupled to cams 61,46 and 53 for simultaneous control of the stitch width, stitch position and direction of work feed respectively, cam 51 being turned to an inoperative position for enabling lever 45 to turn clockwise from its mid position. Knob 41, cam 39 and cam 61 are rigid with the rotatable and axially slidable shaft 40 which is held in its inner position by the engagement of a lug 58 thereon with a frame member 56, when follower 42 is engaged with cam 39. If knob 41 is turned to its zero setting and is pulled outwardly, lug 58 passes through an aperture 57 in member 56, follower 42 is engaged with cam 61, and a clutch member 60 on shaft 40 is coupled with a clutch member 55 on a hollow shaft 54 which is rotatable on shaft 40 and carries the cams 46 and 53. A slidable follower bar 47 is biased against cam 46 by a spring 48 and is pivoted to lever 45. Cam 53 is formed with a deep notch a and fine shallow notches b to f, all of said notches being engageable by a nose 63 at one end of a bar 64 pivoted at 65 and biased towards cam 53 by a spring 66. When nose 63 engages notch a,the other end of bar 64 engages leg 67 to shift pin 26 to the left hand side of groove 23. Bar 64 is clear of leg 67 when nose 63 is engaged with any of the notches b to f. When shaft 54 is uncoupled from shaft 40, nose 63 is engaged with notch f. After shafts 40 and 54 have been coupled together, knob 41 is turned to engage nose 63 in succession with notches a to e, reverse feeding occurring while notch a is engaged to form the left hand side of the buttonhole, and forward feeding occurring while notches b to e are engaged to form the bottom barring, the right hand side, the upper barring and straight locking stitches respectively of the buttonhole. Specification 938,417 is referred to.