Patent GB-1445374-A (GB)
Title: Selective positioning system particularly for onctrolling guide bars of knitting machines
IPC: D04B27/26
Filed: 1973-09-11
Abstract: 1445374 Warp knitting machines SIGMA INSTRUMENTS Inc 11 Sept 1973 [26 Feb 1972] 42712/73 Heading D1C A guide bar of a warp knitting machine is controlled in synchronism with a moving portion of the knitting machine to produce a knitting pattern by producing electrical pulse signals in synchronism with the portion from a stored program representing a part of the pattern so that the pulse signals represent a part of the pattern, producing rotary motion with a stepping motor in response to the signals and applying the rotary motion to the bar as a translatory motion. The needles 16 on a bar are moved between guides 18 on the guide bars 20-24 by a needle control 10. The guide bars are fixed to sleeves 34 fixed to sliding shafts 30 mounted on a rocker panel 32. The guides are rocked transversely of their length by rocker 32 and reciprocated by stepping motors 52-58 through pinions 60, racks 62 and levers 64, 66 pivoted about fulcra 68, 70. Levers 64, 66 are connected at their centres to rods 42-48. The needle control 10, guide bar rocker 36 and electronic system 50 are all coupled to the main shaft 70. Signals from circuits 126, 126a, 126b, 126c operate the motors. The racks 62 are biassed into engagement with their pinions 60 by spring biassed rollers 144 while adjustable brakes 180 are provided for each rack. Rods 48 are connected to the levers 64, 66 by swivel ends at blocks 154 which are adjustable on the levers to vary the motion produced. The position of lever fulcra 60 is adjustable by screws 172. A disc 80 is rotated in unison with shaft 72 and has a hole 82 co-operating with a sensor 84 to produce synchronising signal SYNC1. The sensor may alternatively be optical, sensing the difference between reflected and incident beams, magnetic or capacitive. Another sensor 86 detects an indication 88 on the other side of the disc 80 to produce signal SYNC 2. The leading edge of the signal from sensor 84 triggers Schmitt trigger 90 in one direction and releases at the trailing edge; the leading edge of the output switches or multivibrator to its high state which lasts during e.g. 30 of the cycle of disc 80 and starts cycle timing clock 94 and turns on timing control 96. An address register 97 addressed by control 96 interrogates read only memory 98 for six words-four words for the guides when they travel in front of the needles and four half words when they travel behind. The output from memory 98 reaches buffer storage 100 opened by a signal from control 96. Buffer 100 stores a number of steps for guide movement in front of the needle, a unit step for movement behind and directional data for both. A gate synchronising signal from multivibrator 72 then turns on AND gate 102, starting frequency adjustable oscillator 104 to operating stepping motor driver 106 through OR gate 108. Driver 106 drives motor 56 a number of steps determined by pulses emitted by oscillator 104 and compared with the buffer output and connected by counter 110 so that gate 102 is turned off when the stored number of pulses has been counted. Output B from storage 100 determines the direction of motor 56. SYNC 2 signal occurs about half a revolution of disc 80 later and operates Schmitt trigger 119 and a multivibrator 120 responds to the leading edge of its output, shifting to its high state for about 30 of the disc cycle. Differentiator 121 produces a gating signal along line 122 from the signal's leading edge to turn on AND gate 123 to transmit the unit step at output C of storage 100 through OR gate 108 to motor driver 106. AND gate 124 is also turned on, a signal passing from buffer storage 100 through OR gate 116 to the direction control. For setting up each motor may be operated by a JOG signal at an AND gate 128.