GB1510299A - Method for adaptive control of machining operations - Google Patents

Abstract

1510299 Photo-electric measuring apparatus VERKSTADSTEKHNIK AB 7 July 1975 18706/72 Heading G1A [Also in Division B3] A method of adaptive control of cutting machine tool operations to optimize the productivity of cutting machine tools having controllable cutting parameters affecting its cutting tool comprises the steps of (a) selecting a first set of cutting parameters, (b) performing a machining operation using said first set of cutting parameters, (c) during said machining operation measuring a plurality of times the magnitude of at least one wear-related parameter of the cutting tool, (d) comparing the successive measurements of said at least one wear parameter, (e) calculating the tool life by projecting, based in said comparison step, when said wear parameter will reach a predetermined limiting value, (f) calculating productivity based on said first set of cutting parameters and the tool life calculated in said tool life calculating step, (g) optimizing productivity by selecting further sets of said cutting parameters, and calculating for each set the corresponding tool life, and the productivity resulting from said further sets of cutting parameters and said correspond tool life, and (h) selecting from the productivity values calculated the optimum set of cutting parameters. In an application, the method includes the steps of directing electromagnetic radiation, e.g. a laser beam, towards at least one of a cutting tool and a workpiece; measuring a reflected, refracted or interrupted portion of said radiation representative of at least one of the tool and/or workpiece parameters relating to tool wear and workpiece dimensions, vibration, deflection and surface roughness; and continuing said operation until one of the parameters exceeds a predetermined limit. For measuring tool parameters, Fig. 2, e.g. on a lathe, a laser beam 10 is deflected on to a tool 5 so that part of the beam is reflected through a lens 8 to a detector 12 to measure surface crater wear, and part of the beam is refracted through a lens 13 into a detector 15 to measure flank wear. The measuring takes place when the tool 5 is retracted from the workpiece 4. For measuring parameters, Fig. 3, a laser beam is split into two beams 25, 31 by reflectors 24, 30 to pass through polarizers 33, 34 to partly interfere with each side of the workpiece, and to pass through lenses 26, 32 to detectors 19, 29. The two beams are formed as rectangular cross-section beams and the amount of interference by the workpiece alters the intensity of radiation received by the detectors 19, 29. The laser 21 may provide the laser beam 10, Fig. 2, by means of deflectors 41, 43. The information from the detectors enables parameters relating to the productivity of the operation to be calculated and e.g. a limit set upon the tool life of tool 5. The method can be applied to grinding Figs. 7 and 8, (not shown), end milling Fig. 9, (not shown), and drilling Figs. 10 and 11, (not shown). In an embodiment of the invention Fig. 20, (not shown), a lathe (400) is controlled by numerical control (100) operating through a computer (201) to activate servo-drives on the lathe. Positioning is measured by counting pulses related to ball-screw drives. Limiting parameters, such as maximum and minimum spindle speeds, tool feeds, spindle torque, are entered into a constraint computer (202). The optimization involved parameters are measured "in-process" and parameter adjustments made accordingly. One measured parameter may be surface roughness and a surface roughness measuring instrument Fig. 22, (not shown), comprises a laser beam which strikes the surface to be measured at an angle and the intensity of-the reflected beam is measured.