GB1437145A - Control system for machine tool provided with automatic tool- exchanger - Google Patents

Abstract

1437145 Machine tool control; tool changing TOYODA KOKI KK 26 April 1974 [28 April 1973] 18419/74 Heading B3B [Also in Division G3] In a control system for a machine tool having a tool exchanger, tool storage magazine, and means for extracting tools from the rotary magazine for mounting on a spindle 24, and returning tools to the magazine, there is provided means 50 to detect a broken tool, and, in response thereto, use of first numerical control instruction data provided to a computer controlling the machine tool for routine machining of a workpiece W is suspended, and replaced by second numerical control data which causes return of all tools to the magazine, whence the first numerical control instruction data is reinitiated to machine a new workpiece. The magazine stores spares for specified tools, and, should breakage of one of these be detected, such tool can no longer be called by the first n.c. programme until it is replaced, the instruction for use of the broken tool mcanwhile being replaced by an instruction to use the spare tool. The machine is one of a plurality (M 1 -M n ), Fig. 1 (not shown) each controlled, via control units (MTC 1 -MTC n ), by a central processing, and time sharing, unit (1). Broken tool detector, Fig. 3 (not shown).-With dog (56) restrained relative to spindle head 22 shaft (51) supporting U-shaped detecting head (53) is rotated, and reciprocated under hydraulic control until light source-light receiver combination (54-55) detect the tip of tool (T 10 ), whence dog restraining pins (57, 58) withdraw, the dog henceforth moving with shaft 51, the detector being retracted to an out-of-use position. After use of tool (T 10 ), the detector shaft (51) is again rotated and reciprocated until the dog (56) operates limit switch (59). If, with the shaft in this location, no tool tip is detected, a broken tool signal is provided. Alternatively a broken tool may be detected by a change in the machining cutting resistance. Tool exchanging, Figs. 4, 4a-4f (not shown). Tools are initially withdrawn from, or replaced in, the rotary magazine with sockets (H 0 -H 59 ) by arms (32a, 32b) with gripping hooks, and transferred to a standby tool socket 41, to and from which a main arm 35 with gripping hooks transfers tools from and to the spindle 24. The n.c. data may address a specific magazine socket invariably associated with a specific tool, or each tool may have an identification symbol, and be returned to any empty magazine socket. Tool transfer, as an alternative to the above two intermediate transfer stages, may require only one, or no intermediate stages. In returning all tools to the magazine in response to the second n.c. data, actions which would normally result in the extraction of a tool, are performed in relation to magazine socket (H 0 ) which is always empty. Typical tools which may break are drills or taps.