Patent GB-634528-A (GB)
Title: Improvements in or relating to a work support for machine tools
IPC: B23B5/00
Filed: 1947-08-07
Abstract: 634,528. Work-holders ; boring, drilling and milling machines. GIDDINGS & LEWIS MACHINE TOOL CO. Aug. 7, 1947, No. 21603. Convention date, Nov. 23, 1942. [Class 83 (iii)] A work support for a horizontal boring, drilling, and milling machine comprises a carriage 30 traversable horizontally, a rotatable work-table 40 mounted on a frame on the carriage, and power drive means, including a prime mover, operable selectively to traverse the carriage or rotate the table, the table and power drive means being assembled to form a self-contained structure. The carriage 30, Fig. 1, is traversed by means of a pair of racks 33, Fig. 2, on a bed 32 and carries a sub-base 35, base 36 and frame 37, the worktable spindle being carried on two sets of roller bearings in the frame 37 and one set in a bracket on top of frame 36 ; the bearings are adjustably pre-loaded. The table is rotated by means of a worm-wheel 63, Fig. 6, driven by a worm 64 on a vertical shaft 65 and carries a toothed ring 66, Fig. 9, which is engaged by a toothed clamp plate 70 to hold the table in its adjusted position. The clamp plate is forced into contact with the ring 66 by springs 78 and is withdrawn by a cam 80 rotated by a rack 93 and. pinion 94, the rack being reciprocated by a hydraulic cylinder 91. The cam 80 also acts on a link 86 engaged by pin-and-slot connections with a pair of wedges 83 sliding in grooves 85, and, when the plate 70 is moved to the clamping position, the wedges are moved up so that they hold it securely in that position. Similar clamping means, operated by a cylinder 91a, Fig. 1, is provided on the carriage to lock it to a rack 95 on the bed. To prevent the table deflecting under load, a number of shoes 101, Figs. 2 and 11, are carried on the base 36 and bear on the ring 66. Each shoe is loaded by an adjustable spring 112 acting through a bolt 109 and an arm 108 on a shaft 104 having an eccentric 103 journalled in the shoe. Two electric motors are provided, a reversible motor M, Fig. 6, for rough-positioning adjustments, and a motor M<SP>1</SP>, having a. hydraulic transmission H controlled by a reversing and speedregulating motor RM, for accurate adjustments. A drive is taken from the motor RM to an indicator 240, Fig. 1, which shows the setting of the hydraulic transmission and a pair of limit switches, operated by this drive, limit the range through which the transmission can be adjusted. Either motor M or M<SP>1</SP> may be connected to a main shaft 120 by a disc-type clutch 121 or a clutch 122 comprising a pinion meshing with an internal gear, the clutches being controlled by a pair of hydraulic cylinders 190, 190<SP>1</SP>, Fig. 8. When fluid is admitted to the outer or inner ends of both cylinders, a shift rod 195 is moved to engage either the clutch 121 or 122, respectively, and, when fluid is admitted to opposite ends of the cylinders, the linkage 194 is in the position shown in Fig. 8 and the rod 195 is in an intermediate position in which both clutches are disengaged. A pair of gear clutches 127 and 128, actuated similarly to the clutches 121 and 122 by hydraulic cylinders 209 and 209<SP>1</SP>, connect the main shaft 120 to either a shaft 129 driving the table through a reduction gear-box C or to a shaft 130 geared to pinions 140 engaging the racks 33 on the machine bed. For adjusting the table or carriage by hand, two similar auxiliary drive units D and E are provided and are connected to the power drive by shafts 145 and 160, respectively. In the unit D, a handle 155 has a dog clutch 156 connecting it to a spring-loaded sleeve 157 on a shaft 154 which may slide axially so that gears 153 and 149 are brought into mesh ; an indicator 152 shows the amount of adjustment imparted. Fluid for the hydraulic system is drawn from a reservoir R by a pump P and delivered to a header 250 connected to a relief valve 251. Thence the fluid passes through two-position control valves, such as 252, to the hydraulic cylinders. The valves are preferably remotely controlled by means of solenoids, the circuits of which may be interlocked to ensure operation of the units in the proper sequence. Lubricating systems.-Two separate lubricating systems, having pumps P<SP>1</SP> and P<SP>11</SP>, respectively, draw oil from a reservoir R<SP>1</SP> and deliver it to various parts of the support. Relief valves 263 and solenoid-operated valves 261, which may be interconnected with the valves in the hydraulic system, are provided and in some lines, a non-return valve 262 is fitted.