GB877527A - Buttonhole sewing attachment for sewing machines - Google Patents

Abstract

877,527. Sewing-machines. SINGER MANUFACTURING CO. March 6, 1959 [March 10, 1958], No. 7941/59. Class 112 A buttonhole sewing attachment includes a frame 11 to be fixed to a sewing-machine, a work shifting member or shank 29 mounted to undergo swinging and sliding movements on the frame 11 and formed with an upwardly offset portion 43 having secured thereto a pattern template 53 formed with an endless rack 55, a cam member 75 journalled in the frame 11 and mounted in a space between the frame and the offset portion 43 to drive a cam follower 90 also mounted in the said space, and a pinion 111 having its axis arranged to follow the movement of the cam follower and arranged to be turned about that axis as a result of such movements, the pinion being in mesh with the rack on the pattern template. The shank 29 carries a presser foot 26 and has a slot 32 engaged by a fulcrum pin 31 extending vertically from an angle bracket slidably mounted on a raised side wall of the frame 11 and adjustably secured thereto. A pointer 41 extends from the angle bracket to indicate the position of the fulcrum pin and hence the amplitude of the presser foot's lateral movement. The offset rear portion 43 of the shank has a large aperture 50 spanned by the removable pattern template, two locating pins in the latter entering corresponding holes in the portion 43. The pins may differ in size from each other so that the template may be fitted in only one position. The underside of the template 53 is provided with an endless slot 54 defining the shape of the buttonhole. The slot is entered by the upper end of a stud shaft 91 fixed to a plate 93 which is slidable on a platform attached to the frame. The lower end of the stud shaft carries the cam follower 90 which tracks a groove 76 in the cam 75. The cam is secured to a ratchet wheel 74 pivoted on the frame and rotated by a pawl 79 which is oscillated by a bell crank 17 one arm of which is connected to the needle clamp of the sewing machine. Rotation of the cam causes transverse oscillations of the follower 90, the stud shaft 91 and the slide plate 93. The presser foot is thus oscillated from side to side with an amplitude determined by the selected position of the fulcrum pin 31. As the plate 93 oscillates a pawl 112 engages a ratchet wheel 110 secured to the pinion 111 thus giving step-by-step rotation to the pinion, which moves along the pattern rack to shift the presser foot in the closed path dictated by the slot 54. To position the pinion 111 on a particular part of the rack the operator actuates a spring biased lever 120 pivoted on the shaft 91 and carrying a pawl 123. The pawl engages the ratchet wheel 110 to rotate the pinion. To prevent flagging of the work a plate pivoted on a stud 16 is provided with a finger 140 spring biased towards the work. A follower lug 148 on the plate overlies a cam 149 on the bell crank lever 17. The cam is arranged to lift the lug, and the finger 140, after the needle has ascended out of the work. The device has a cover 60 provided with a hinged lid 63. A spring 66 secured to the inside of the lid presses on the template to retain the latter in position when the lid is closed.