Patent GB-955199-A (GB)
Title: Improvements in blind stitch sewing machines
IPC: D05B1/24
Filed: 1962-03-12
Abstract: 955,199. Sewing machines. UNION SPECIAL MACHINE CO. March 12, 1962 [March 13,1961], No.9381/62. Heading D1G. A blindstitch sewing machine comprises a frame, a drive shaft journalled in the frame, a work support pivoted at its rear end to the frame about an axis transverse to the direction of work feed, said axis being provided by cylindrical means co-operating with pivot means on the frame eccentrically of said axis, a ridge-former pivoted to the work support about an axis positioned in front of the pivotal axis of the work support, connections from the drive shaft to the work support for rocking the latter to produce skip stitches, and means operable at will for turning said cylindrical means about said pivot means for rocking the work support to facilitate the introduction and removal of work. The upper arm 11 of the main frame 10 journals the main drive shaft 15 which is connected via an eccentric 17 and pitman 18 to a crank arm on a shaft 19 journalled in a forwardly-extending arm 12. An arm 20 rigid with shaft 19 carries a curved needle 21 which co-operates with a looper 22 carried at the front end of a rod 23. The latter is mounted intermediately for sliding and swinging movements, and is pivoted at its rear end to a block 25 fixed to a pin 26 pivoted in an angled position 27 of a crank 28 fixed to shaft 15. A feeding foot 29 is carried by the front end of a bar 30 which is mounted intermediately for sliding and swinging movements and co-operates at its rear end with an eccentric 32, which may be adjustable on shaft 15. A work support 13 is formed at its rear edge with spaced lugs which are journalled on a shaft 44 mounted eccentrically at its ends on fixed tapered pivot pins 45 and 48. Work support 13 is held in the raised position by a pair of toggle links 51 and 53 pivoted together at 56, link 51 being pivoted at 52 to an arm 66 and link 53 being pivoted at 54 to work support 13. A bar 57 connects pivot 56 to a collar 60 rigid with shaft 44. A spring 63 acts on a collar 61 rigid with shaft 44 to bias the latter angularly for straightening the toggle. The work passes between a foot 33 fixed at the end of arm 12, and a pair of ribs 34 pivoted to arms 36 which are pivoted at 37 to a frame member 14a carried at the end of an extension 14 of work support 13. A spring 38 acting on arm 36 biases rib 34 upwardly. Movement of arm 36 is limited, when the work support is lowered, by the engagement of a nose 39 on arm 36 with a plate 40 fixed to frame 14a. An oscillatory ridge-former 105, located between ribs 34, is fixed to one end of a shaft 106 journalled in the work support, the other end of shaft 106 being connected via a crank 110 and pitman 112 to an eccentric 114 on shaft 15. Arm 66, pivoted to toggle link 51, is pivoted on a fixed pin 67 and is rigid with an arm 72. A link 73, pivoted at 72a to arm 72, has an adjustable screw connection 74 to a block 75 pivoted at 76 to one arm of a bell crank lever 77 which is pivoted at 78 to a fixed bar 79. A roller 80 on the other arm of lever 77 abuts a cylindrical member 81 pivoted on a fixed pin 83, and is held in contact therewith by a spring 70 acting on an arm 68 rigid with arm 66. A pin 84, crossing a peripheral notch 81b in member 81, is engaged with the notched lower end of a lever 85 which is pivoted intermediately on shaft 15. Manipulation of the upper end of lever 85 serves to turn member 81 to align a peripheral notch 81a therein with roller 80 which thereby rises, with a corresponding fall of work support 13 to a skip stitch position. A gear 86 fixed on shaft 15 meshes with a gear 87 journalled on pin 83. A cylindrical member 82 is fixed eccentrically on gear 87 whereby, when notch 81a is aligned with roller 80, the latter will remain engaged with the periphery of member 82 to rise to and descend from the skip stitch position. Gear 86 may make either two revolutions or three revolutions for each revolution of gear 87. The position of bar 79, slidably mounted in frame 10, may be altered by rotation of a knob 89 to vary the depth of penetration of the needle 21. For lowering of the work support to introduce or remove work, a knee press 92, carried by a bar 93, is adapted to rotate a shaft 99, journalled in frame 10, via a rotary shaft 95 and gears 97 and 98. A roller 101, carried by an arm 100 rigid with shaft 99, thereby engages the under surface of an arm 103 rigid with toggle link 51, for lowering the work support. Bar 57 simultaneously causes rotation of shaft 44 accompanied by downward shifting of the axis of the latter. Controlling threads. When the knee press 92 is operated to lower the work support, a thread lock 116 automatically closes. The thread lock comprises a pair of discs 124 biased together by a spring 122 but normally held apart by a pin 125 carried at the upper end of a bar 126. The lower end of the latter is pivoted to one arm of a bell crank lever, the other arm of which abuts a collar on a slidable rod 129, the end of which shuts a lug 131 rigid with collar 61 on shaft 44. When the lever press is operated, shaft 44 turns and lug 131 moves away from rod 129 to allow bar 126 to fall by gravity. The thread on its way from the thread lock to the needle passes through a tensioner 115 comprising a pair of discs 121 biased together by a spring 120. The discs 121 are moved apart to release the tension, each time the needle withdraws from the work, by means of a pin 117 co-operating with a cam 118 on shaft 15. U.S.A. Specifications 2,109,014 and 2,588,274 are referred to.