Patent GB-1019727-A (GB)
Title: Improvements in blindstitch sewing machines
IPC: D05B85/06
Filed: 1964-08-31
Abstract: 1,019,727. Sewing machines. UNION SPECIAL MACHINE CO. Aug. 31, 1964 [Sept.16, 1963], No. 35515/64. Heading D1G. A blindstitch sewing machine comprises a rotary drive shaft, first connections from said shaft for oscillating a curved needle, a pivotallymounted work-supporting member, an oscillatory ridge-former mounted on said member, and second connections from said shaft for oscillating said member and including a pair of co-operating levers, and adjustable means carried by the machine frame for varying the effeetive length of at least one of said levers to vary the extent of oscillatory movement imparted to said member. The machine has a base 10, from the rear of which rises a standard 11 supporting an upper horizontal arm which journals a driving shaft 17. An arm 14, projecting forwardly from a head 15 at the free end of said arm carries a fixed workengaging plate 41, and houses connections from shaft 17 for actuating a swinging needles 28, a looper 29, and a work-feeding foot 33. A shaft 48, fixed in lugs 49 extending upwardly at the front end of bases 10, journals a work-supporting member 15 from which a lower horizontal work-supporting arm extends parallel to the upper arm. A spring acts on member 15 to bias a pair of presser feet, against the lower surface of plate 41. An eccentric 82, journalled on a shaft 74b journalled in turn in standard 11, is driven by gearing from shaft 17, and is connected by a pitman 83 to a crank-pin 84 on a disc 85 pivoted on a shaft 86 journalled in member 15 and the lower arm. A disc fired to shaft 86 adjacent disc 85 carries a spring-biased pin adapted to engage one or the other of a pair of diametrically-opposed depressions in disc 85 for positioning one or the other of a pair of ridge-forming members, carried by shaft 86, in the upward or operative position. A spring is interposed between disc 85 and member 15 to permit slight axial displacement of shaft 86. A rod 56, slidable in base 10, abuts at one end a disc 54 carried by member 15, and is biased by a spring 57 to abut at its other end a lever 59 pivoted at 60 on base 10. The rounded upper end 59a of lever 59 abuts the lower end of a lever 61, the forked upper end 61a of which is pivoted to a pin 62 carried by a stud 63. The latter screws into a pin 64 which is journalled in standard 11 and carries an external knob 65. A disc 72, carried by a pin axially slidable in the forked end 61a, is embraced by a member 77 which is slidably mounted in standard 11 and is shiftable by means of an external knob 75 to engage disc 72 with either an eccentric member 74 or a concentric member 74a rigid with shaft 74b, the latter being driven by 2 to 1 reduction gearing from shaft 17. The arrangement is thereby such that when disc 72 engages eccentric 74, levers 59, 61 are rocked to impart reciprocating movement to rod 56 and thus oscillatory movement to member 15 for producing skip stitches Rotation of knob 65 serves to vary the position of abutment between levers 59 and 60, whereby shifting of said position towards the free end of lever 60 increases the degree of oscillation imparted to member 15. A pin 65p depending from knob 65, co-operates with the notches in a Geneva wheel 68 Fig. 18, not shown, pivoted at 69 to standard 11, whereby each rotation of knob 65 shifts a fresh numeral, provided on the periphery of wheel 68, beneath a window 70 to denote the number of revolutions turned by knob 65. A scale 65c on the latter co-operates with a fired pointer 71 to denote fractions of a revolution. Bearings 17a, 17b, Fig. 1 not shown, for shaft 17 are provided with oil reservoirs 137, 139 supplied by passages 136, 138. A wick 141, contained in a tube 140, conveys oil to the strap of pitman 83 engaging eccentric 82 for lubricating shaft 74b generally. A knee pad, for use in lowering member 15 at the end of a sewing operation, is connected by a rod 93 to a member 94 having a tapered connection 94a with a sleeve 95 secured by a stud 98 to a shaft 97 journalled in base 10. A sleeve 100, fired to shaft 97, carries an arm connected by a chain 102 to member 15. A spring connected between base 10 and a pin on a sleeve 104 fired to shaft 97, biases a surface of sleeve 104 against a stud carried by base 10. The angular position of the knee pad may be varied by loosening a clamping screw 96 and turning member 94 relative to sleeve 95. A vertical rod 112, slidably mounted in a sleeve 110 and U-shaped bracket 113 carried by standard 11, is provided at its upper end with a disc 108 and is spring-biased downwardly to abut its lower end with a stud 117a carried by an arm 117 which is pivoted to a lug 118 on bracket 113 and abuts a sleeve 119 fired to shaft 97, whereby disc 108 is raised above an upper flange 109 of sleeve 110. Needle thread passes through a guide 110a and between the members 108, 109 on its way to a thread tensioner 125 mounted on head 13. When the knee pad 92 is actuated to lower member 25, arm 117 engages a flat surface on sleeve 119, whereby rod 112 is lowered to clamp the thread between members 108, 109, when a pull on the workpiece will serve to snap the thread. Access to rod 112 is furnished by a door 121 covered internally with sound-absorbent material 121a and provided at its lower edge with a spring finger 122 adapted to engage the lower edge of the door opening, the upper edge of the door being secured by screws 123. The thread tensioner 125 comprises a base 129,Fig. 19 not shown, mounted on a rubber disc 127 and secured to head 13 by a screw 128. A casing member 130 is secured to base 129 and carries a thread guide 124. A knob 131 has a screw-threaded stem 131a which passes freely through a disc 126 and the top of casing 130, and screws into a disc 132 located within the latter. A pin 133, fired to base 129, prevents rotation of discs 126 and 132. A compression spring 134 biases knob 131 downwardly to engage disc 126 with the upper surface of casing 130 to apply tension to a thread passing therebetween, the tension depending on the vertical position of disc 132 varied by turning knob 131. Disc 132 may be engaged with a surface 129a of base 129 for raising knob 131 out of engagement with disc 126. A stud 135 screws into the free end of stem 131a to prevent disengagement of disc 132 therefrom. An auxiliary work support 146, Fig. 34 not shown, is pivotally mounted on base 10 and extends along the lower arm. A U-shaped bracket 146a, secured by screws 146b to base 10, carries in one arm 146c a vertical pin 146e which is adjustably secured therein by screws 146b, and is formed in its head with a cam groove 146k. The other arm 146d carries a vertical pin 146m adjustably secured therein by screws 146n and provided with a collar 146q. A depending portion 146p of support 146 is pivoted on the upper part of pin 146m, and is supported by rollar 146q. Another depending portion of support 146 carries a downwardly spring- biased pin 146g adapted to engage groove 146k releasably for retaining support 146 in the operative position. A work guide 147, Fig. 33 not shown, has a turned-over edge 147a adapted for slidable engagement with the inner edge of member 146, and a vertical work-engaging flange 147b which co-operates with a scale provided on the upper surface of member 146.