Patent GB-1209601-A (GB)
Title: Machine tool with automatic tool change facilities
Inventor: SHOTTER DOUGLAS RALPH
IPC: B23Q3/157
Filed: 1967-02-02
Abstract: 1,209,601. Machine tool detents; tool changer. ALFRED HERBERT Ltd. 26 Jan., 1968 [2 Feb., 1967], No. 5107/67. Headings B3B, B3C and B3K. A machine tool with automatic tool changing comprises a tool spindle head 34, Fig. 1, pivotal about a horizontal axis on a slide 33 vertically movable on a column 32, a chain-like tool magazine driven by sprockets 36, and a tool transfer device including a pair of grippers 141, 142. Head 34 has two spindles, one of which can be loaded with a tool from the magazine, while the other one is operating on a workpiece which is carried by a work-table 31a movable with a controllable feed in two perpendicular horizontal directions for milling or drilling. The magazine is formed by links 37 pivoted together at 50, Figs. 4, 7, each of which carries a tool 38, and a tool identification element whose output is compared with a tape control coding 61, which is read by a reading head 99, Fig. 1, having switches. Tool 38 is located in link 37 by a frusto-conical spigot 39, a key in a notch in a flange 42 on the tool, and a spring-urged latch 65 which is released by a pusher 138 actuated by a peg 134a, which co-operates with an eccentric 134. The latter also actuates a plunger 131 which locks the selected link 37 in the desired position ready for tool changing. Each of the tool spindles 73, Fig. 23, comprises a collet 72, actuated by an hydraulic piston and cylinder unit 75. The tool transfer device comprises a frame 81, Figs. 1 and 14, vertically movable on guides 84, 85, and connected to the slide 33 for vertical movement therewith, by a slotted plate 82. The device is counter-balanced by a weight. Grippers 141, 142 are mounted in a head 157, Fig. 18, mounted on carriage 143, Fig. 14, and rotated thereon by a fluid-actuated rack 162, and pinion 161, and they are secured to the ends of bars 172, 173, Fig. 18. The bars are coupled by a pinion 180 engaging racks on the bars, and are moved in the head by fluid supplied to piston and cylinder units 174, 175. Each gripper comprises a main tool gripper having a fixed jaw 181, and a pivoted jaw 182, Fig. 19, and an auxiliary tool identification element gripper having a fixed jaw 183, and a pivoted jaw 184. The jaws 182, 184 of each gripper are coupled to an hydraulic actuating device 185, 186. In operation, a machining step is completed by a tool in one of the spindles 73, head 34 is indexed to bring the other spindle into working position, and slide 33 is repositioned if necessary. A desired tool is placed in position in the magazine, a switch is actuated, valve VB, Fig. 26, is energized to drive the tool transfer carriage 143 forwardly. When a switch LS2 is actuated, valve V 4  is energized to release a brake 128, and plunger 131, Fig. 4, engages the link 37. At the end of the forward movement of carriage 143 pusher 138 releases latch 65 so that tool 38 can be withdrawn from link 37. Grippers 141, 142, Fig. 26, are extended so that a switch LS7 is actuated, and the grippers are positioned to grip the tool and the element 61, which are to be transferred. A switch LS3 is actuated so that a valve V 6 A closes the gripper jaws on the tools and elements 61, after which a pressure switch P 3  is actuated. Valve V 8  is energized to release the tool spindle collet, causing pressure switch P to be actuated. Valve V 5  is energized so that bars 172, 173 are withdrawn to remove the tools and the elements 61 from the link 37 and the spindle 73. A switch LS6 is actuated, indicating that the tools are fully withdrawn, valve V 1 A is energized to return carriage 143, and switch LS1 is actuated. Head 157 is now required to be indexed in one direction or the other, and if switch LS4 is actuated, valve V 2 A will be energized, and if switch LS5 is actuated, valve V 2 B will be energized. At the end of the indexing movement, the switch LS4, or LS5, not previously actuated, will now be actuated. Carriage 43 is moved forward, switch LS2 is actuated so that empty link 37 is re-aligned. At completion of the forward movement switch LS3 is actuated to cause valve V 8  to operate, and extend bars 172, 173, so that the tool and element 61, removed from the magazine, are placed into spindle 73, and the used tool and element are placed in the magazine. Actuation of switch LS7 causes de-energization of valve V 8  so that the collet closes on the tool. A time delay switch causes valve V 6 B to be energized, so that the grippers can release the tools and elements. Actuation of switch 14 signals the energization of valve V 1 A, so that carriage 143 is retracted. The machine is now ready for the next tool change.