Improvements in or relating to machine tools

摘要

959,594. Machine tool details. CROSS CO. Feb. 20, 1961 [March 7, 1960], No. 6225/61. Headings B3B and B3C. [Also in Division G1] A machine tool head 12, Fig. 2, carrying drills 16, 18, is slidable on a base 10 towards and away from a workpiece 14. Inductance coils 28, 30, carried by a member 32 are fixed in relation to the base 10, and apertures 34, 36, in member 32 allow the drills to pass through the coils to drill the work. The coils may be embedded in the member 32 or they may be wound on bobbins inserted in member 32, the bobbins acting as drill bushes. Dogs Al, A2 carried by head 12 are adjusted to actuate limit switches LS1, LS2 at the instant when drills 16, 18 are just entering coils 28, 30 if the drills are the required length, and a trouble indication will not be transmitted. However, if a drill is broken or set at an incorrect length an oscillator circuit including the coil will carry a signal which is amplified and either operates a warning light or stops the machine. Limit switches LS1, LS2 may be replaced by variable inductances, and the coils may be in axially stepped relationship so that the drills will enter the coils simultaneously, thus allowing only one switch to be used. In a modification, Fig. 5, normal length and unbroken drills 161, 181 never leave coils 281, 301 and a trouble indication will not be produced until one of the drills is not disposed in a coil. Specification 936,953 is referred to.