The processes carried out by machine tools are divided into two types????????????????progressive???????? e.g. profile milling, grinding, turning, in which cutting and traversing operations occur simultaneously, and ????????non-progressive????????????????e.g. drilling, boring, punching????????in which they alternate. The requirements for automatic control of each type o1 process are considered in detail, and a specification worked out for a ????????basic???????? system of position control for application to ????????non-progressive???????? processes, to which may later be added facilities for carrying out some ????????progressive???????? processes. The design of a driving and measuring system for attachment to existing machines is derived, and from it are inferred the requirements of the control system, the major design features of which are then discussed. Finally, the possible use of the system in conjunction with punched card or similar programming devices is examined, and extension of its use to some ????????progressive???????? operations considered. The avoidance of complex electronic circuitry is made the governing factor in deciding the methods to be employed throughout.
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