Patent GB-986262-A (GB)
Title: Improvements in or relating to sewing machines
IPC: D05B59/00
Filed: 1964-03-09
Abstract: 986,262. Sewing machines. MEFINA S.A. March 1964 [June 26, 1963], No. 9800/64. Heading D1G. The zig-zag machine adapted for sewing buttonholes as described in Specification 828,476, in which a lever controlling the amplitude of needle swing is coupled with limited relative movement to a plate pivoted, with said lever, coaxially with a rotary cam generating the needle swing, whereby said plate can be positively located in two angular positions corresponding respectively to a left hand line of stitching with reverse feed and a right hand line of stitching with forward feed, is modified by mounting a manipulating knob for the lever on a stem which is pivoted in the lever 7 and which can be located positively in three angular positions, in the first of which a part rigid with the stem cooperates with fixed angularly-spaced notches, in the second of which the lever can turn freely, and in the third of which said part enters with play a part in said plate for coupling the letter to the lever. A gate 2, pivoted on a fixed spindle 3, carries at one side the needle bar 1 and is pivoted at the other side to one end of a bar 4. The other end 6 of the latter is biased by a spring 30 against a slide 7 on a lever 8 pivoted at 11 to the machine frame 12. A follower roller 28 on lever 8 engages a cam 29 rigid with a rotary shaft 22 journalled in a fixed sleeve 23. A lever 24 pivoted on sleeve 23 has an arm 25 carrying a pin 26 engaged in a slot 27 in bar 4. Pivoting of lever 24 via its other arm 31 thereby serves to shift end 6 along slide 7 for varying the amplitude of needle swing derived from cam 29. Lever 10 carries a depending pin which is biased by a spring 68 against a cam surface 15 in a wheel 16, turning of which thereby pivots lever 10 for varying the line of stitching. Arm 31 pivotally carries a stem 33 provided with a manipulating knob 34 and with a cross pin 43. The end of arm 31 is formed with mutually perpendicular slots 45, 46, and stem 33 is biased inwardly by a spring 47, whereby pin 43 may be engaged either downwardly in slot 46, or to the left in slot 45, or upwardly in slot 46. Pin 43 when positioned downwardly can engage selectively with notches 42 in an arcuate plate 77 which is pivoted at one end to the machine frame 12 and at the other end to a fixed leaf spring 79. Notches 42 correspond to numbers 0, 1, 2, 3, 4 indicating stitch width and masked adjacent knob 34 on the exterior surface of frame 12. When pin 43 is positioned to the left, lever 24 may be turned freely against the friction provided by a spring-biased brake block 38. For the sewing of buttonholes, wheel 16 is adjusted to a left hand line of stitching and stem 33 is adjusted to mark 2. Pin 43 is then positioned upwardly and enters a notch 53 formed in a plate 54 pivoted on sleeve 23. The machine is provided with feed-control mechanism similar to that described in Specification 957,497, whereby when the adjusting knob of said mechanism is turned to a position denoting automatically-controlled feed, a pin 61 on a feed-control lever 57 enters a notch 62 on plate 54, and pin 43 is biased against the right hand side of a notch 53 to set a reverse feed. The left hand side 69 of the buttonhole is then sewn. Knob 34 is then moved to the right, whereby pin 61 engages a notch 63 in plate 54, while stem 33 is set to mask 4, forward feed being established and a nose 66 on plate 54 cooperating with a nose 67 on lever 10 to shift the latter to a position corresponding to a right hand line of stitching. The upper barring stitches 70 are then sewn. Knob 34 is then moved leftwards to engage pin 43 with the left hand side of notch 53, corresponding to mask 2, for sewing the right hand side 72 of the buttonhole. Finally knob 34 is moved to engage pin 43 with the right hand side of the buttonhole for sewing the bottom barring stitches 73. Specification 683,291 also is referred to.