Patent GB-1435170-A (GB)
Title: Method and apparatus for controlling the cutting of sheet material
IPC: B23Q35/128
Filed: 1973-11-02
Abstract: 1435170 Automatic control of cutting SCHUBERT & SALZER MASCHINENFABRIK A G 2 Nov 1973 [2 Nov 1972] 51045/73 Heading G3N In the cutting of sheet material [cloth] wherein a tracing device [optical, inductive or mechanical] following a pattern controls the movement of a knife cutting the material, the detection of a mark 5, Fig. 3 on the pattern causes de-activation of the pattern sensor (60), Fig. 1 (not shown) normally tracing with a lead (B) with respect to effective pivot points (6), of tracing device 61 and knife 73, deceleration of the device and knife in a distance A, pivoting of the knife by a predetermined amount, forward and backward traversing of the knife over a predetermined distance in the new direction, followed by re-activation of the sensor (60). Using this technique nips 35 can be cut, and individual patterns [e.g. (20, 22 Fig. 1)] can be placed closer together than the lead (B) provided markers 5 are provided for each nip position, or corner closer than (B) to an adjacent pattern.  Corners without marker are traversed by the tracer and knife pivoting to the right [or left] in the presence of a sensor signal [external corners], otherwise pivoting to the left [or right] [internal corners], until the contour line is again found. In tracing the pattern of Fig. 2 (not shown), wherever corners abut, the knife and sensor pass the intersection without change of direction unless markers are provided, in which case, a pivot and traverse takes place leading to a right or left hand turn. Markers may be used to cause the knife and sensor to follow a connecting line (10) between non-  contiguous patterns (27, 28). The lateral sense of a nip may be reversed [e.g. right to left], by combining a marker with further regions (103, 104', Fig. 2) effectively reversing the roles of pattern and background. The marker is sensed by having an effective luminance intermediate that of pattern and background, provided by narrow strips 52, Fig. 3, or an area (51 Fig. 1) of intermediate luminance. The markers take the form of adhesive labels. Corners without markers may be traversed by pivoting in one sense only, connecting areas [e.g. (32, 33 Fig. 1)] obviating the need for discontinuous pivoting in the other sense. Control arrangement, Fig. 4. Tracing is normally controlled by adjustable timer 8, knife orientation control 63 and delay control 64, the former control via motor 72 and reversing clutch 74 controlling knife orientation, the latter controlling x and y co-ordinates of knife-material relative translation, the material being fixed or partaking of one of the degrees of translational freedom. Detection of a marker 5 causes changeover, via 62 to control by unit 71, directional control 67 causing pivoting of the knife for a time pre-set in timer 68, followed by outward and rearward traverse each for the time set in coupled timers 69, 80, whence control reverts to unit 70. For tracing a corner with marker, the process under control of unit 71 is repeated until the contour line is again found. The sensor may provide pulse or continuous signals. The timers may be electronic, mechanical, or electromechanical.