GB829110A - Improvements in metal-cutting machine tools - Google Patents

Abstract

829,110. Multi-station drilling and milling- machines. KEARNEY & TRECKER CORPORATION. April 9, 1956, No. 10754/56. Class 83 (3). A machine-tool comprises a work-supporting table movably mounted on a base, and a clamping mechanism actuated by fluid pressure to force the table into tight engagement with the base, or to exert a pressure in the opposite direction to raise the table from its base and interpose a quantity of fluid between the table and base so as to support the table on a column of fluid to facilitate, its movement relative to the base. The work-table 20, Fig. 1, carries four work-holding fixtures 36 adapted to grip automobile cam-shafts, and is indexible to four different stations. The first station "A" is for loading and unloading. At the second station " B," face-milling cutters 21, 22, operate on the ends of the workpiece; at the third station " C " axially-opposite drills 27, 28, drill centre-holes, and at the fourth station " D " one end of the work is drilled by a tool 29. Each tool has the same drive and support means, which comprise a self-contained electric motor 26, a carriage 23, and guideways 24. The carriages are fed by fluid pressure (oil) piston-and-cylinder devices, with automatic-stop, quick-approach and return valve gear described below. Work-table indexing and clamping.-The table 20, Fig. 3, is supported in its working and clamped position on a member 34 carried by the bed. When thus supported a switch LS4 is closed and other parts of the machine may then be operated. A central boss 45 of the table is guided in a cylindrical recess 44 of the member 34. Piston-and-cylinder devices are built into the boss 45, together with an antifriction bearing 56, so that the table may be lifted before indexing, supported then by fluid (oil) pressure and the bearing 56 (shown diagrammatically in Fig. 9). The table, after indexing, is forced down on the, support 34 by fluid-pressure on the opposite side 75, Fig. 9, of a piston fixed to the support 34. The table is indexed by a fluidmotor 173, Fig. 7, which rotates a worm 179, worm-wheel 186 and pinion 191, the latter engaging a toothed rim 192 of the table. A locking-plunger 216 enters a recess 217 in notchplates on the table at the indexed positions. The plunger is fed and retracted at the required times by a fluid-pressure piston-and-cylinder device connected thereto and shown diagrammatically at 215, Fig. 9. A cam and switchplate 211 is driven by further gearing from the motor 173 and operates a valve 276 to slow down the drive when the table is almost at the end of an indexing operation. Switches are moved sequentially so that all the operations of the machine take place in the proper order and only after other operations have been completed. The machine is started after an electrical system has been energized, by a hand lever 148, Fig. 9, controlling a starting valve 144. Fluid pressure is passed from electricallydriven pumps 164, 328 to operate the parts of the machine in automatic sequence. The piston- and-cylinder device 145 operates a clamping fixture for the work-holding members 36, and pressure for this is passed up through the centre of the post supporting the work-table. Tool-slide actuation.-All the tool-slides are similarly arranged. That shown diagrammatically in Fig. 9 carries a milling-cutter 21 and is reciprocated by a piston 294 connected to the tool-slide 23 and working in a cylinder 292 carried by the slide-support. The slide 23 is advanced at a rapid-traverse rate until the tool nearly engages the work, whereupon a rod 307 is operated by a dog 308 to meter the fluidsupply to a feed-rate. A dog 309 finally trips a switch LS5 which, through a solenoid 302, operates a reversing-valve to return the toolslide.