Patent GB-287527-A (GB)
Title: Improvements in sewing machines
IPC: D05B15/04
Filed: 1928-03-17
Abstract: 287,527. Union Special-Maschinen-fabrik Ges. March 23, 1927, [Convention date]. Blind-stitching machines; multiple-needle machines. - The pair of opposite needles for the through stitches and the needle for the blind stitches in the apparatus described in Specification 275,149 for making the seam described in Specification 280,585 are supported on arms so that the through stitching needles are disposed on opposite sides of the seam and enter the fabric alternately, and are both given a dwell when out of the material to permit feeding of the fabric. The through stitching needles 7, 20 are mounted on arms 8, 31 oscillating on the fixed shaft 11. The arm 8 has a projection 12 with a curved slot 13 in which works a roller 14 carried by the strap 15 of the eccentric 6 turned by the rotating shaft 5. The strap is connected to the frame 2<c> of the machine by the doubly pivoted link 17 so that when the roller 14 is travelling up the slot 13, the arm 8 is not rocked, and the needle 7, being at this time out of the fabric, is given the dwell during which the fabric is fed. When the roller is at the top of the slot, the pivot 18 has been moved so that the descent of the roller causes the arm 12 to rock the arm 8, so forcing the needle into the fabric for the next stitch. The needle 20 is similarly operated by a projecting arm with the slot in the opposite direction. The needles 7 and 20 have loopers 44, 46 which move in an elliptical path to spread the loops from one needle for the other one to enter. The looper 44 is carried on a shaft 43, Fig. 8, with a ball stud 42 engaging a strap 35 operated by the eccentric 33. The strap is pivoted at 40 to a link 36 pivoted to a fixed arm 38 at 37. As the eccentric 33 is rotated by the shaft 5, the strap 35 oscillates the looper shaft 43 by means of the ball stud, and rocks about the pivot 40, imparting an up-and-down motion to the shaft. This gives the looper the necessary elliptical movement. The looper 46 is similarly operated. The blind stitching needle 21, Fig. 1, is mounted on an arm rigid with the arm 31 of the needle 20 and enters the fabric at the same time therewith. The looper 56 for the needle 21 has to move to-and-fro over the seam for the blind stitching. It is mounted on a shaft 57 carried in a bearing 63 and is oscillated by a ball stud 62 connected to an eccentric strap 60, Fig. 3. It is reciprocated by a system of links 73, 79, 81 from an eccentric on the shaft 5, and pulled across the seam by an eccentric strap 67 pivoted to the member 78 to which the link 79 is pivoted. The fixed shaft 11 is adjustable in its bearings by the mechanism described in 279,100. Trimming or cutting.-The edges of the material laid on the work support are trimmed by knives 86, 87, Fig. 11. The knife 86 is fixed to the presser foot 94 and the knife 87 is mounted on an arm 88 pivoted on a bar 89 of the presser foot. The other end of the arm carries a ball stud 90 engaging a link 91 engaging a ball stud 92 on the arm 8 of the needle 7, so that as the needle arm moves, the knife 87 moves to-and-fro for trimming. Presser-feet.-The presser-foot 94 is provided with an adjustable finger 109 which serves as a stitch finger and edge-depresser.