Patent GB-639916-A (GB)
Title: Improvements in or relating to stitching machines
IPC: D05B65/00
Filed: 1948-02-27
Abstract: 639,916. Sewing-machines. BRANDWEIN & CO. A. Feb. 27, 1948, No. 6048. Convention date, April 14, 1941. [Class 112] [Also in Group XXIV] Thread-cutters.-In a machine comprising a stitching mechanism mounted on a carriage which is moved to produce a line of stitching, a thread-cutter is actuated at the end of the stitching operation by mechanism mounted in part on the carriage and in part on a stationary member. In the embodiment shown, a chain-stitch machine 11, Fig. 5, is mounted on a carriage reciprocated on rails 7 transversely of a frame 1 to produce successive lines of stitches, during its forward movements, in a length of work, such as mattress boxing, which is fed longitudinally of the frame during the backward movements of the machine. The thread cutter comprises a blade with a shank 113, Fig. 10, sliding in a guide 111 and lying close to the looper 115 ; it is connected to a substantially vertical spring-biassed lever 117 which carries a roller 118 on its lower end. When the carriage reaches the end of its movement an abutment 129 thereon engages a thrust member 128 adjustably fixed to a toothed sector 126 rotatably mounted on the frame 1, and this causes movement of a similar sector 125 to move the cutter-actuating lever 117 by means of an arm 127, to which a return spring is attached. Feed by rollers and by moving machine.-The carriage carrying the stitching machine 11, Fig. 5, is reciprocated on the rails 7 by an adjustable link 31 connected to a lever 28 which has a roller engaging a cam groove in a disc 51 on a vertical shaft 22 driven by worm gear from a motor-driven shaft 13. Feed rollers 74 carried by standards 73 on the frame 1 and geared together are actuated by a ratchet arm 78 connected by a pitman 82 to an adjustable crank 83 on a horizontal shaft similarly worm-geared to the shaft 13. The timing of the cam and the crank are such that the roller feed is actuated during the idle return movement of the stitching machine carriage. Work holding and guiding ; threads, controlling otherwise than in stitch-forming.-The work approaching the stitching machine 11 passes between rollers 68 which are spring-pressed together and are carried in brackets extending towards the machine from a relatively distant cross-bar on the frame 1. During stitching the work is supported by a plate 134 extending from the feed-roller standards 73, and is held by a gripper 138 pivoted to the plate and lifted, to permit feed, by a linkage from a vertically-sliding bar engaging a cam face on the disc 51. The presserfoot 93 is lifted at the end of the forward motion of the stitching-machine by mechanism including lever 89 and an arm 97 on the carriage carrying a roller which comes into contact with cams 105 on the frame 1 at the ends of the movements of the carriage, the lever 97 being thus rocked over deadcentre, with the assistance of a spring, at the end of each movement. A thread pull-off finger on an arm 95 is actuated by connection to the lever 89 to ensure that sufficient thread remains in the needle when the thread is cut. Driving ; stopping.-The stitching machine 11 is driven from the shaft 13 by chain gearing to a jackshaft 35 and thence by two chains 46, 47 with their common intermediate sprocket wheel at the pivotal joint of two arms supported respectively by the jackshaft and the transversely-arranged main shaft of the stitching machine ; this arrangement accommodates the movement of the machine on its carriage. The jackshaft 35 is formed in two parts connected by stop-gear which disconnects the drive during each return movement of the machine by means of a lever 53 actuated by the cam disc 51. The Specification as open to inspection under Sect. 91 also describes the stop-gear in detail, as follows :- The clutch comprises an outer member a, Fig. 16, an inner member b fitting over a spigot on the member a, and a member f, shown dotted, which is mounted for slight rocking on the member b by a spigot d in a bearing in the latter member ; the spigot d carries a roller c which is pressed into contact with the member a, to transmit the drive from a to b, by a spring g acting between the members b, f to rock the latter clockwise. A stop arm 62, Fig. 5, is carried by a shaft 58 controlled by the cam lever 53 and is moved by a spring, just before the machine reaches the point at which the presser-lifting and thread pull-off mechanism is actuated, to project a nose into the path of an abutment formed by a notch j in the member f. The nose first engages an eccentric part of the member f to rock the latter so that the clutch roller c is moved clear of the driving member a and then enters the notch j to stop the machine with the needle raised. This subject-matter does not appear in the Specification as accepted.