Improved control method and apparatus for mechanical copying machines

Abstract

Abstract 672,853. Photo-electric control of copying- machines. LINDE AIR PRODUCTS CO. July 12, 1950. [Aug. 30, 1949] No. 17401/50. Class 40 (i). [Also in Group XL (b)] The invention relates to the control apparatus of copy-milling machines of Specifications, 561,171, [Group XL], 583,520, wherein a rotating shutter interrupts a beam of light passing by the edge of a template to energize a photo-electric cell, the resulting pulses from the photo-cell being fed through a mechanical or electrical switching mechanism operated in synchronism with the rotating shutter to a driving means controlling the relative movement of the cutting tool and the workpiece in each of the four component directions of a co-ordinate system. The improvement of the invention comprises the addition of an amplifier followed by a generator which translates the variable pulses from the photo-cell into pulses of fixed duration and transmitting these constant duration pulses to the switching arrangement. As shown, Fig. 2, a tracing head comprising a light source 10, a rotating shutter 12 and photo-cell 14, is mounted for horizontal movement relative to a template 16, the output of the cell 14 being fed through an amplifier 28 and constant duration pulse generator 30 to quadrature phase speed amplifiers 18, 20, 22, 24 operating a North-South motor 38 and East-West motor 46, driving the tracing head, the amplifiers 18-24 being switched in synchronism with the rotating shutter 12, so that the position of the photo-electric pulses in the cycle determine the direction of travel of a work piece relative to the cutting head. The shutter 12 may have a simple pin-hole, or a series of pin-holes on varying radii, or an arcuate slot, or an eccentric semi-circular opening.

Inventors

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Bibliographic Details