Patent GB-938417-A (GB)
Title: Improvements in or relating to sewing machines
Inventor: ERIKSSON ALLAN HERMAN
IPC: D05B19/00
Filed: 1962-06-26
Abstract: 938,417. Sewing machines. HUSQVARNA VAPENFABRIKS A.B. June 26, 1962, No. 24570/62. Addition to 839,671. Class 112. [Also in Group XXIV] In a zig-zag sewing machine a plurality of side-by-side rotary control cams selectively cooperate with a cam follower, a rotary handle is adapted both to shift the cams and follower relatively to one another along the axis of rotation and also to lift the follower from the cams, the handle being inoperative for lifting the follower in certain angular positions, the number of which is at least two but is less than the number of cams, one of the cams is adapted to produce a normal zig-zag seam, the shifting means comprises a cam in two consecutive angular positions of which the follower engages said zig-zag cam, and the handle is connected with means adapted, upon turning the shifting cam between said angular positions, to actuate a member for changing the stitch position. A hollow shaft 14, journalled on a fixed shaft 15 and driven by gearing 16 from the arm shaft 7, has slidably but non-rotatably mounted thereon a pack of cams comprising cams a to f co-operating selectively with a camfollower 40 for controllling the needle bar vibration, and cams g, h of greater diameter cooperating selectively with a cam follower 53 for controlling the work feed. The swinging gate 4 for the needle bar 5 has pivoted thereto one end of a bar 42, the other end of which is biased by a spring 43 slidably against follower 40 pivoted at 39 to one arm of a two-armed lever 47 pivoted at 74 to the machine frame. A rotary cam 44 co-operates with a follower 45 connected by a link 46 to bar 42 for shifting the latter along follower 40 to vary the stitch width. Connected to the other arm of lever 47 is a bar 49 biased by a spring 50 against a rotary cam 48 normally set for centrally positioned stitching. Follower 53 is one arm of a three-armed lever 53, 54, 55 pivoted at 56 to the machine frame. A bar 57 extending from arm 54 controls the angular position of a pivoted guide 12 for a slide block 11 pivoted on a pitman 10 actuating the feed advance shaft 9. A handle 25 is rigid with a shaft 24 which is journalled in the machine frame and has journalled thereon a sleeve 22 formed with a stepped helical cam slot 21 engaged by a nose 20 on a bar 18 which is slidable on a fixed rod 19 and is coupled to the cam pack. A dial 26, disposed between handle 25 and the front wall 23 of the machine frame, is rigid with a sleeve 27 journalled on shaft 24. The latter is coupled by a shaft 28 and gearing 29, 30, 31 to sleeves 22 and 27 in such a manner that for half a revolution of handle 25, sleeve 22 rotates one-sixth of a revolution and sleeve 27 rotates one-seventh of a revolution. Cam slot 21 has six steps 33 to 38 spaced equi-angularly apart, the axial spacing being equal to the axial spacing of the control cams. Step 33 has a continuation 32 angularly aligned with step 38. Dial 26 has seven equally spaced pattern diagrams A1 and A to F indicating the stitch patterns produced when nose 20 engages the respective steps 32 to 38. A disc 60, fixed to shaft 24, has two diametrically-opposed cam lobes 61 separated by notches 62. A bar 64 has one end coupled by a pin and slot connection 67 to an arm 66 rigid with follower 40, has its other end forked to embrace shaft 24, and is biased by a spring 65 to engage a pin 63 thereon with a notch 62 when nose 20 engages one of the steps of cam slot 21 and one of the diagrams on dial 26 is opposite a fixed pointer 70. A bar 69 is pivoted at one end to bar 64 and has a pin and slot connection 68 at its other end with the lever arm 55. When pin 63 engages a notch 62 connections 67 and 68 allow followers 40 and 53 to oscillate freely. When handle 25 is turned through half a revolution, pin 63 is transferred from one notch 62 to the other notch 62 and in riding over lobe 63 raises the followers 40 and 53 while the cam pack is being shifted axially by a cam width. When nose 21 engages steps 38 and 37, follower 40 engages cams f and e, and follower 53 engages cams h and g to produce patterns F and E respectively. When nose 20 engages steps 36 to 33, follower 40 engages cams d to a to produce patterns D to A respectively. In all the foregoing positions, cam 48 normally positions the stitch field centrally. When nose 20 engages step 33 normal zig-zag sewing A is produced. When nose 20 engages extension 32, a cam 27 rigid with shaft 24 engages the adjacent end 51 of an arm of lever 47 to turn the latter counterclockwise for producing the pattern A1, namely normal zig-zag sewing with the stitch field positioned to the extreme left. It is stated that the cam 48 may be omitted, when the extension 33 is lengthened to angular alignment with step 37, the advance of sleeve 27 is reduced to one-eighth of a revolution, and sleeve 27 is provided with cams adapted to co-operate with lever 47 for producing right-hand, left-hand and central stitching for the three respective angular positions of dial 26 in which cam a is operative.