GB1088884A - Machine tool control apparatus - Google Patents

Abstract

1,088,884. Machine tool positional control. ZAVODY PRESNEHO STROJIRENSTVI GOTTWALDOV, NARODNI PODNIK. Jan. 21, 1965 [Jan.31, 1964], No.2685/65. Heading G1N. An apparatus for automatic positional setting of a carriage 1 (Fig. 2) of a numerically controlled machine tool comprises elements for coarse and fine setting, the fine setting element including a potentiometer 22 the wiper 21 of which is rotated, via a shaft 16, by the moving mechanism of the tool carriage, and the potentiometer is connected in a bridge circuit, including resistors 34, 35, fed from a stabilized D. C. source U. The bridge unbalance output, resulting from the angular position of the wiper 21, is fed to an amplifier 39 which is selectively connected either to an amplifier 46 feeding the tool carriage drive 47 or to a meter 51 for initially zeroing the system, so that in operation the drive continues until the bridge is balanced. The carriage should then be in a position determined by a numerical control equipment (not described) with an accuracy to the nearest millimetre. If accuracy to 1/100th m. m. is required a second potentiometer 41 is connected to the bridge by the closure of switch 40' and the opening of switch 40. The bridge will again be unbalanced and the drive 47 will again move the carriage and the wiper 21 until the bridge is balanced. The potentiometer 41 wiper position is adjustable manually in correspondance with an appropriate indicating scale. The moving mechanism of the carriage 1 comprises a revolving screw 2 in a fixed nut 3 which screw is coupled to a coarse positional setting arrangement including contact discs 4, 5, 6. Disc 4, which measures decimetre lengths of carriage displacement from a position preselected by a programme control, is geared to the contact disc 5 which measures centimetre lengths and is in turn geared to the contact disc 6 serving for millimetre length measurement. An output shaft 7 of the contact disc 4 is coupled via gears 9, 10 and a clutch 14, 15 with the drive shaft 16 of the wiper 21. The operator first coarsely sets the carriage to a programmed position the attainment of which is signalled by a lamp (not shown), and the deflection of meter 51 should be substantially zero. The potentiometer 22 is then adjusted until the meter 51 reads zero and the system is then ready for automatic fine adjustment. The potentiometer, 22 is a continuous ring comprising one turn of resistance wire, and the wiper has unlimited angular movement.