GB1371668A - Method and apparatus for producing stitching patterns cyclically - Google Patents

Abstract

1371668 Sewing machines VIRGINIO RIMOLDI & C SpA 23 May 1972 [17 June 1971] 24201/72 Heading DIG In a sewing assembly a workpiece is held against a table top 2 and moved along by a clamping arrangement 12, through a sewing machine 4, the speed of the clamp being changed at chosen points during the cycle by control circuitry. There are a series of holes in the table top, and air is sucked down through them to keep the workpiece flat on the table. The clamp approaches the machine at a first speed, slows down to allow stitching of a short length of seam at a second speed, completes the main part of the seam at the first speed, slows to finish the seam at the second speed, travels to the workpiece discharging station at the first speed and stops. The clamp is raised thus activating a switch 72 to reverse the direction of movement and the clamp returns to the beginning at a 3rd speed, higher than the 1st speed. To permit accurate positioning of the clamp on the workpiece the speed is reduced to a 4th speed, slower than the 2nd speed. The speeds are altered at the chosen positions by a timing device, and the three lowest speeds may be varied. The clamp is driven by a continuously running motor 5 and a chain 6, prongs 9 on the clamp carriage engaging the upper or lower run for forward or return movement respectively. A guide groove 17 on the clamp engages a peg 18 on the sewing machine to displace the clamp transversely to sew a curved seam, the clamp being unlocked for transverse movement only after its leading edge actuates a sensor 62. Telescopically extending arms 13, 14 join the clamp to a carriage 3 and a pneumatically operated piston 30 raises and lowers the arm. Initially the clamp is positioned using a template 19. A pneumatically actuated thread cutter device 68 is provided to cut the thread after the sewing machine has stopped. To begin the cycle a foot pedal 32 is operated to lower the clamp onto the workpiece, and the starting button 48 is pressed. By pressing and releasing the foot pedal the clamp may be lifted and lowered. Sensors 60, 61, 62, 65, 72 and photo electric cell 46 operate in conjunction with electric control circuitry (Figs. 8, 9, not shown) which actuates pneumatic controls (Fig. 10, not shown).