GB1304662A - - Google Patents

Abstract

1304662 Programmed control of thread cutting machines SICME S R L SOC ITALIANA COSTRUZIONI MECCANICHE 19 April 1971 [17 March 1970] 24479/71 Heading G3N Axial and radial movements of a thread cutting tool U are controlled by a system in which the required movements and thread parameters are set up in registers on a control panel 43 and the machine operation is represented by pulses. These are produced by a marked disc 38 on the machine spindle with photodetectors 40, 41 and there are two trains, Qo one pulse per revolution and Q a multiple thereof. They are supplied to an interpolator 42 into which is also fed information P of the pitch of the thread, the output Cl'o being passed to a logic circuit 44. This circuit also receives the remainder of the information from the control panel and information from tool carriage position detectors FCAO, FCAI and FCBO, FCBI and operates stepping motors MPA, MPB so as to follow the programme of movements shown in Fig.2. From a datum position O the tool moves a distance lo (set on Lo) and radially ao (set on Ao). butting commences over a distance 11 with a depth of cut i1 which is repeated n1 times, followed by further cuts of depths i2, i3, etc each repeated n2, n3 etc. times respectively. The pulse generator 38 --- 41 is used only during actual cutting. For other movements pulses from an oscillator are used, their frequency being varied to produce smooth acceleration and deceleration. The system may be extended to cut two or more different threaded sections in sequence, or modified to allow for multi-start threads or threads with tapered (in depth) lead-in or exit. For the latter, the desired taper is set up in terms of number of revolutions per increment depth of cut, and a non-linear taper may be programmed by specifying a change in this parameter in stages. It is mentioned that facilities for automatic change of tool may be provided and programmed on panel 43.