Patent GB-754898-A (GB)
Title: Improvements in or relating to button sewing machines
IPC: D05B3/14
Filed: 1954-08-20
Abstract: 754,898. Sewing-machines. PFAFF AKT.-GES., G. M. Aug. 20, 1954 [Sept. 23, 1953], No. 24245/54. Class 112. A button-sewing machine has a button-applying clamp 29 which applies the button solely under the influence of spring means 30, and which, at the end of the stitching cycle is withdrawn from buttonapplying position by resilient means 32 which has been stressed during the stitching cycle and which is made operative without impact on the stitching mechanism. The button clamp is pivoted to the work support 4 of the machine and is biased downwardly by spring 30. The clamp is held in the raised position by the engagement of a pin 28 on the clamp with the lower end of a lifting arm 21 which is pivoted at 26c to a lever 26 pivoted at 31 to the overhanging arm 2 of the machine, a trip link 20 being pivoted at 20a to the lifting arm 21. The latter is biased upwardly by spring 32 which is attached to lever 26, and is also biased rearwardly by a spring 22 attached to the trip link 20. The arrangement is such that, on the commencement of the operating cycle, link 20 moves rearwardly to stress spring 20 and also to swing arm 21 rearwardly, thereby releasing the button clamp. Lever 26 is then rocked to stress spring 32 and also to lower arm 21 to a position wherein the end of the latter is arcuately aligned with pin 28, lever 26 being latched in the rocked position. Link 20 is released near the end of the operating cycle, when spring 22 moves link 20 forwardly to engage the lower end of arm 21 with pin 28. Lever 26 is unlatched at the end of the operating cycle, whereby spring 32 rocks lever 26 to raise arm 21 and the button clamp therewith. A control shaft 7, carrying a cam disc 36 formed with a pair of notches 38, is driven from a main shaft carrying a fast pulley 5 and a loose pulley 6. A belt-shifting fork 9 is attached to a belt-shifting lever 10. Pivoted to the latter at 11 is a bar 12 which is pivoted intermediately to a lug 13 pivoted to the machine frame. The front end of bar 12 which is slidable in a bracket 40 secured to the machine frame, carries a forwardly facing stud 19 and an upwardly extending lug 16. Link 20 is also slidable in bracket 40 and has, near its rear end, a cranked portion 23 which, in the position shown, engages the rear surface of lug 16, the rear end of link 20 being formed with a sloping cam surface 24. A latch member 48 is pivoted at 49 to bracket 40 and has a lower extension biased by a spring 50 into engagement with stud 19. The rear end of lever 26 carries a cam follower roller 34. When lever 10 is operated to start the machine, bar 12 is moved rearwardly, whereby lug 16 co-operates with crank 23 to move link 20 rearwardly, when the button clamp is released and spring 22 is stressed. Roller 34 then leaves notch 38 and rides on the periphery of the cam disc, when lever 26 is rocked for lowering arm 21 and stressing spring 32, and spring 50 moves the upper end of latch member 48 into engagement with a lug 52 secured to lever 26. Near the end of the operating cycle a stud 39 on the cam disc engages the cam surface 24 to raise the rear end of link 20, whereby the lower edge of the latter rides on lug 16 and spring 22 moves link 20 forwardly to engage arm 21 with pin 28. On completion of the operating cycle, lever 10 is moved to shift the belt to the loose pulley, when bar 12 moves forwardly, whereby stud 19 rocks latch 48 to release lug 52, and spring 32 rocks lever 26 to raise arm 21 and the button clamp against the force of spring 30.