GB667044A - Combined sewing and trimming mechanism - Google Patents

Abstract

667,044. Sewing machines. COLUMBIA SEWING MACHINE CORPORATION. Aug. 25, 1949 [Sept. 4, 1948], No. 22100/49. Class 112. [Also in Group XXIV] Trimming; presser-feet.-An attachment for trimming or pinking the edge of work being sewn in an ordinary machine comprises relatively movable cutting blades actuated from the needlebar; the operating mechanism preferably provides for actuation of the blades only at every other stroke of the needle, or less frequently, and also for putting the cutting mechanism out of action; in the embodiment described the cutting blade moves horizontally, and the work is bent upwards at the edge by the presser-foot or a separate guide. In the arrangement shown, looking in the direction of feed, the fixed blade is formed by two sharpened edges of a triangular hole in a plate secured in a vertical plane to the right-hand side of the presser-foot shank 15, which is correspondingly apertured, and the moving knife 23, of V section, has an extension which is guided in an upward enlargement of the hole in the fixed blade. The edges of the pieces of fabric being sewn are bent up and guided by a slot 21 in the presser-foot 16 to lie in a suitable position relative to the knife 23; in a modification, a narrower presser-foot of ordinary form is used, with a depending guide plate close to its right-hand side to guide the fabric edges. The knife 23 is reciprocated by a lever 34 pivoted at 35 and having its other arm formed as a toothed sector for engagement with a similar sector on a spindle 51 which is oscillated from the needlebar ; the arm 34 and the mechanism are carried by a bracket 24 clamped on the presser-bar, and the knife 23 is pressed downwards by a spring plunger 43 mounted in this bracket. The mechanism comprises a member 48 pivotally, attached at one end to the needle-bar 5 and supported from the spindle 51 at the other end by a link 50, an arm 53, linked to the member 48, rotatably mounted on the spindle 51 and carrying a pawl 54, and a member 55, fixed to the spindle 51 and formed with an abutment for engagement by the pawl 54 and an opposing abutment for engagement with a stop screw on the arm 53 by which the member 55 is returned to its initial position with the arm 53. In order to provide that the blade 23 is not operated at every stroke of the needle, the pawl also engages a ratchet wheel 56, which is free on the spindle 51 and provided with a detent 71, and the notches of this ratchet wheel are of different depths, so that some of them prevent the pawl 54 from descending into engagement with the member 55, the ratchet wheel thus providing for a predetermined sequence of effective and idle strokes of the arm 53; the pawl 54 can be raised and held clear of both members 55, 56 by a finger lever 65 with a cam surface engaging the arm 53, when it is desired to sew without cutting.