Linear control of machine tools using fluidic devices

Abstract

This thesis is concerned with the development and manufacture of a fluidic variable event control system for turret lathes, which can be programmed to give any desired tool-slide length of travel in increments of 0.001 inch. The system consists of pneumatic-hydraulic machine actuating cylinders, fitted with sensors to provide machine information, and a control cabinet containing the logic, counter, address and programme systems. Control of events, such as the engagement of the cross-slide, change of feed etc., have been related to the ram-slide motion; fluid displaced from the ram-slide actuating cylinder is metered into either a storage tank or slave cylinders in the control cabinet which, repeat and amplify the motion. Sensing units fitted to the slave cylinders, are programmed to inform the Logic System when the machine slide has travelled the required distance for an event, which initiates command signals to the address system. Programming a selection of events, their sequence and distance to be travelled by a tooling arrangement is achieved by sing multi-channel selector units. Each unit has six programme channels and controls and event, such as the rate of feed for each turret face. On receipt of a start signal, programme channel number 1 of each selector unit is energised, turret face number 1 is presented to the component material and the events programmed take place. When the sequence of operations for that turret face have been completed, the slides return to their starting point. Indexing of the turret to present face number 2 energises programme channel number 2 to control events for this face. This process is repeated until turret face number 6 and programme channel number 6 has been used; the component has now been completed and the cycle is repeated. The programme is not pre-determined such as when using plug board, punched card or tape, and can be varied by shop floor personnel adjusting the programme selector units while the machine is in operation. This feature not only enables component lengths to be adjusted, but as the choice of such events as speed, feed, or when to start the cross-slide may be varied to suit the actual working conditions, optimum production performance is more readily achieved.