GB1332446A - Method of and apparatus for cutting die blanks - Google Patents

Abstract

1332446 Milling FRANKLIN MINT CORP 4 April 1972 15270/72 Heading B3K [Also in Division H4] A method of cutting a coining die comprises the steps of rotating a die blank 22 and a depth shade picture to be reproduced mounted on a rotating disc, at the same speed in the same direction, optically scanning the picture at 40 and generating output signals indicative of shade depth, and cutting the die blank with a tool 24 to reproduce the picture in three dimensions on the blank by moving the tool across and toward and away from the blank in response to the signals. A milling machine 10 comprises an arm 14 on a frame 12, the arm being pivotally supported by a universal joint 16 mounted on a carriage 18 and movable vertically by a lead screw 28. An end milling tool 24 and sensor 40 are carried by arm 14, and are adjustable therealong. A servo control system is used to control the movement of arm 14 into and out of the paper Fig. 1, and comprises a photo-cell 42 Fig. 3, whose output signal is proportional to the instantaneous optical density of the rotating picture. An error signal is generated by comparing the output signal with the feedback signals 60, 62, 64, the error signal is then passed through amplifiers 50, 52, to control motor 46 arid cause arm 14 to change position. Signal 60 is obtained from a rotary potentiometer coupled to motor 46, signal 62 is obtained electrically from signal 60, and signal 64 is obtained by means of a feedback proportional to the motor current.