Patent GB-871955-A (GB)
Title: Improvements in sewing machines
Inventor: SLINN WALTER HERBERT
Filed: 1956-10-26
Abstract: 871,955. Sewing machines. TRUBENISED (GREAT BRITAIN) Ltd. Oct. 18, 1957 [Oct. 26, 1956], No. 32695/56. Class 112 In apparatus for guiding a workpiece under the needle of a sewing machine along a predetermined stitching line, a holder for the workpiece is mounted on a carriage movable in each of two mutually perpendicular directions in one plane, and the means for effecting movement of the carriage in one of the directions include a pair of substantially parallel links, one pair of adjacent ends of the links being respectively coupled to a driving member and to the carriage, and the other pair of adjacent ends being pivotally connected to a lever, the pivotal connection to the lever of one of the links being adjustable along the length of the lever, whereby to vary the movement imparted to the carriage by a given movement of the driving member. A workholder 7 is mounted on a carriage 8 slidable on parallel rods 9. The latter are fixed at their respective ends to sleeves 10 slidable on fixed rods 11 disposed at right angles to rods 9. Levers 12, fixed at their lower ends to a shaft 13 journalled in fixed bearings 14, are pivoted at their upper ends to blocks 15 vertically slidable in the sleeves 10. A pin 16 on one lever 12 engages a cam groove in a disc 17 fixed to a driving shaft 18, whereby the workholder is moved in a direction parallel to the rods 11. An arm 23a of a link pantograph 23, fulcrumed on a fixed pin 33, is provided with a head 20 which engages slidably in a channel under the carriage 8, whereby rocking of arm 23a imparts movement to the workholder in a direction parallel to the rods 9. The pantograph also comprises parallel links 23b, 23c which connect arm 23a to an arm 23d parallel to the latter. A cam slot in a cylindrical cam 39 on shaft 18 is engaged by a follower pin 38 on a crosshead 36 slidable on fixed rods 37. The crosshead is connected by a link 41 to the outer end of a lever 44 fulcrumed on a fixed pin 47. The outer end of lever 44 is also formed with a longitudinal slotslidably receiving a block (not shown) which carries a pivot pin 52 and which can be moved to adjusted position within said slot by means of a rotatable knot 53. A block 60, pivoted on pin 52, is movable by means of a rotatable knob 62, to adjusted position within a longitudinal slot formed at one end of a link 42. The other and bifurcated end of the latter is pivoted at 34 to the pantograph link 23c, the ends of pivot 34 being slidable in a bracket 51 fixed to crosshead 36. Knob 53 thereby adjusts the stroke imparted to pivot 34 and knob 62 adjusts the datum position of the stitching. The arrangement is used for stitching around a collar of a standard size and also of sizes differing slightly from said standard size. The roller is cut out around the sewing by a shaped trimming knife. The Provisional Specification describes a trimming knife comprising a base plate, a knife plate mounted thereon, and a ribbon knife carried by the knife plate and formed into the collar shape to be cut. To render the knife adjustable, the knife plate is divided into two sections each of which carries the knife for one end of the collar. One section is fixed, and the other is adjustable in a direction lengthwise of the collar. For intermediate sizes of collars the sections are moved apart and the gaps are bridged by short lengths of knife mounted on blocks adjustable on the base plate in a direction widthwise of the collar. Specifications 709,621 and 745,474 are referred to.