Sewing machine

摘要

The pulse-controlled drive for the upper fabric advance system in a sewing machine, to work with the lower fabric advance mechanism, uses an incremental transmitter (12) at the main shaft (11) of the sewing machine (1). The measured values it produces, under the supervision of the operative, are used with the nominal value transmitter at the sewing machine control (8) for the nominal and actual rotary speeds together with the acceleration and braking characteristics of the sewing machine (1) and motor (4), representing typical values, during each rotation of the main shaft (11), before the start of an advance phase of the lower fabric advance system (15). During the next fabric advance phase, the expected rotary speed or speed range is computed at the control (41) for the upper fabric advance system (17). The anticipated speed, together with the set stitch length, gives the profile of the drive pulse to control the step motor (19) which is computed in the control (41). This gives a synchronised movement of the advance mechanism with the advance movement of the lower fabric advance system (15). Also claimed is a sewing machine assembly with the control (8) linked to an operating panel (52) and incremental transmitter (12), and with a power unit acting on the motor (4). The control (41) for the upper fabric advance mechanism (17) is linked to the control (8), with a further operating panel (48) and a further power unit acting on the step motor (19) and actuators for the upper fabric advance (17). The control (41) and the operating panel (48) are at a housing (46) at an arm (2) of the sewing machine (1). The carrier plate, attached to the arm (2), has the step motor (19) with its stub shaft for the toothed belt disc, and at least two rotating deflection rollers. A jib, with longitudinal sliding movement, is in the roller guide system, with at least two further deflection rollers, with the sliding movement applied by a compressed air cylinder at the carrier plate to press it against an adjustable spring. The toothed belt, as the advance medium, passes round the toothed belt disc and the deflection rollers.