Patent GB-1379194-A (GB)
Title: Machine tool with automatic tool changing device
IPC: B23B31/26
Filed: 1973-02-14
Abstract: 1379194 Tool changers TOYODA-KOKI KK 14 Feb 1973 [25 Feb 1972] 7293/73 Heading B3B A machine tool with an automatic tool changing device comprises a bed 10; a workpiece supporting means 11, 13, 15 movably mounted on the bed; a column 16 supporting a spindle head 17 having a spindle 23 which comprises first engagement means for driving a cutting tool; a tool magazine 71 for supporting a plurality of tools and indexable to bring a required tool to a tool change position P2 and wherein each tool has second engagement means engageable with the first engagement means of the spindle; tool changing means 49, 64; first detecting means connected with the drive spindle for detecting a first angular position of the first engagement means on the drive spindle; second detecting means for detecting a second angular position of said second engagement means on the tool held by the tool changing means; first control means responsive to outputs of the said first and second detecting means and generating an output corresponding to the difference between the first and second angular positions; and second control means for rotating either the said tool at the position P2, or the spindle, in response to the said output of the first control means to bring the first and second engagement means into coincidence, whereby in a tool changing operation the tool and spindle can be brought into driving engagement. The first and second engagement means comprise drive keys on the spindle and recesses in the tool or its holder 26. The first detecting means comprises a synchro-generator (41), (Fig. 2, not shown) mounted on the rear end of the spindle 23 and the second detecting means comprises a synchro-generator mounted on a tool exchange arm 49 and coupled for rotation with a tool receiving socket (50) (Fig. 3, not shown) that can also be driven by a D.C. motor (58) through at least 180 degrees to engage a spring plunger in one of the said recesses in the tool holder 26. The first control means comprises a circuit linking the synchro-generators (41), (61) (Fig. 5, not shown) and fed with A.C. current to produce a signal corresponding to the out-of-position of the driving keys and recesses. The second control means comprises a rectifier and amplifier for using the said signal to actuate the motor (58) to rotate the synchro-generator (61) on the tool change arm 49 to thereby rotate the socket (50) which holds the tool until coincidence of angular position is reached. Machine tool detents.-The tool change arm 49 takes a tool from the magazine to an intermediate position P1. A further arm 64 having two sets of gripping fingers 65, 66 is rotated 180 degrees to make a tool exchange. The magazine 71 is movable along guides 70 and suspended by a chain 77 from a counterbalancing jack 81. The spindle head 17 is also attached to the jack 81 by a chain 76 so that as the spindle head is moved vertically, the magazine follows. The tool is held inthe hollow spindle by a draw bar operated ball locking sleeve (Fig. 2, not shown) which engages a locking stem on the tool holder 26.