Patent GB-918043-A (GB)
Title: Improvements in or relating to sewing machines
IPC: D05B19/00
Filed: 1961-09-05
Abstract: 918,043. Sewing-machines. MEFINA S.A. Sept. 5, 1961 [Sept. 7, 1960], No. 31856/61. Class 112. In a zig-zag sewing-machine a manually-operable wheel 37 is fixed to a rotary shaft 36 carrying cams which control the operation of the machine in a manner such that at the zero setting, zone 89, of the wheel 37, the machine will sew a straight seam, the lateral position of which is manually adjustable; in zone 90 the needle swing is derived from a three-lobed rotary cam while the stitch width is controlled by rotation of wheel 37 and the centre line is manually adjustable separately ; in zone 91 the stitch formation is derived from a direct-acting rotary pattern cam, the width of the pattern being controlled by rotation of wheel 37; and in zone 92 a recurrent pattern is also produced, the needle swing being derived from the three-lobed cam, the centre line being controlled by said pattern cam, and the stitch width being controlled by a separate rotary cam. The gate 8 for the needle bar 4 is pivoted about a vertical journal 9, and is biased by a spring 10 to engage a roller 15, carried at one end of a rod 14, the other end of which is pivoted at 13 to gate 8, with a slide 16 pivoted at 17 to an arm 18 pivoted at 19 to the machine frame. Slide 16 is adapted to be oscillated by a rotary threelobed cam 21, but the follower pin 20 on slide 16 is disengaged from cam 21 when roller 15 is positioned between the pivots 17 and 19. Roller 15 is connected by a link 25 to an arm 27a pivoted at 28 to the machine frame. A spring 45 biases roller 15 towards the free end of slide 16. A twoarmed lever 30, pivoted at 31 on arm 27a, is adapted, when swung counter-clockwise, to engage an end 35 with an abutment 34 on an arm 27a, also pivoted at 28, whereby arms 27a and 27b are locked relatively to one another against the bias of a spring 33 to engage a follower pin 46 on arm 27b with a stitch widthadjusting cam 47 fast on a rotary shaft 48. A wheel 76, pivoted at 78 on an arm 79, is formed on its upper surface with a spiral cam groove engaged by a follower pin 83 on one arm 82 of a two-armed lever pivoted at 73 to the machine frame. Rotation of wheel 76 thereby rocks arm 82 to engage the other arm 84 with a stud 85 on an extension 87 of arm 18 to rock the latter for varying the centre line of the stitches. Arm 79 is also pivoted at 73 and is spring-biased inwardly to engage a pin 81 thereon with a cam 39 fast on a shaft 36 rotatable manually by means of a control wheel 37, whereby end 84 may be engaged with or disengaged from stud 85. A cam 40 on shaft 36 is adapted to cooperate with lobes 43 and 44 on lever 30 for respectively unlocking and locking the arms 27a, 27b. A rod 64, pivoted at one end to arm 18, carries intermediately a roller 70 biased by a spring 71 against a cam 38 on shaft 36, and is formed at its other end with a nose 63 engaged with a slide 61 pivoted at 62 to the machine frame. A follower pin 60 on slide 61 is adapted to co-operate with a cam 59 on shaft 48 for imparting oscillation to arm 18, but is disengaged from cam 59 when the nose 63 bears on slide 62 at the other side of the pivot 62. A gear 49 on shaft 48 meshes with a gear 50 journalled on the arm shaft 2 of the machine. A block of eccentrics 52 of different eccentricity is slidably but non-rotatably mounted on shaft 2 and is formed with a circumferential groove 58 cooperating with a cam 42 on shaft 36. Rotation of the latter thereby serves to shift the eccentrics axially for selective engagement with a roller 52 mounted at one end of a lever system 53, 106, the other end of which carries a pawl 55 co-operating with a ratchet-wheel 56 rigid with gear 50 to rotate the latter intermittently at selected speeds. In the zero position, zone 89, of wheel 37 cam 40 unlocks the arms 27a, 27b to disengage follower 46 from cam 47, and a cam 41 on shaft 36 co-operates with a roller 32 on pivot 31 to shift roller 51 beyond the pivot 17 of slide 16 for disengaging follower 20 from cam 21. Roller 70 engages a surface 66 on cam 38 nearest the shaft 36, whereby nose 63 is displaced to a position beyond the pivot 62 of slide 61 for disengaging follower 60 from cam 59. The machine will then sew a straight seam, the position of which can be displaced laterally by wheel 76. When wheel 37 is set to zone 90, followers 46 and 60 will remain disengaged from their respetive cams 47 and 59, and cam 41 will co-operate with roller 32 to vary the position of roller 15 on slide 16, and hence the magnitude of the stitch width derived from cam 21. The centre line of the stitches may be varied by wheel 76. When wheel 37 is set to zone 91, cam 41 cooperates with roller 32 for disengaging follower 20 from cam 21, cam 39 co-operates with pin 81 for disengaging arm 84 from stud 85 to render wheel 76 inoperative, and roller 70 alternatively engages flats 67, 68, or 69 on cam 38 to position nose 63 selectively along slide 61. Oscillation of the gate 8 is thereby controlled wholly by cam 59 via arm 18. When wheel 37 is set to zone 92, the arms 27a and 27b are locked together to engage follower 46 with cam 47 and cam 41 is disengaged from roller 32, while cam 38 shifts nose 63 to the free end of slide 61 and cam 39 renders wheel 76 inoperative. The stitch width is then controlled by cam 47 and the stitch position is controlled by cam 59. Movement of wheel 37 through zone 92 serves to shift the eccentrics 52 axially, via cam 42, whereby the length of the recurrent pattern corresponding to one revolution of shaft 48 may be either increased or diminished. Feeding.-The direction and rate of work feed is controlled manually by a knob 102 movable along a slot 103 over a scale 104. When knob 102 is placed in position A, a follower pin 94 on an arm 95, pivoted at 96 to the machine frame, is engaged with a cam 93 on shaft 48 for regulating the feed automatically. The free end of arm 95 carries a pin 99 engaged in a slide 100 extending radially from the feed control shaft 101. Application 33977/61 and Specification 779,038 are referred to.