Patent GB-871095-A (GB)
Title: Machine tool indexing and pallet clamping mechanism
IPC: B23Q16/10
Filed: 1959-06-23
Abstract: 871,095. Milling; machine tool details. KEARNEY & TRECKER CORPORATION. June 23, 1959 [June 27, 1958], No. 21500/59. Class 83 (3). A machine tool comprises an indexible table 23, automatically operative power means relatively to move the table and frame axially for urging a radially toothed clutch 67 on the table into engagement with a clutch 68 on the frame, and means for indexing the table when the clutch is disengaged. A milling and boring machine has an axially movable spindle 34 in a head 32 adjustable on a column 28 movable along ways 24, 25. A pallet 41 may be slid manually or automatically on to ways 37, 38 on the rotary table 23. A head 40 engaging flanges 54, 55 on the pallet can be moved downwardly to clamp the pallet against four conical pins 45, 48 engaging recesses in the pallet. It is moved by a rod 59 actuated by a piston rod 116 in a cylinder 94 attached to a head 95, the rod carrying stops to actuate switches 129, 132. Initial clamping, initiated by a manual control knob, is at an adjustable low pressure, but actuation of the switch 129 causes the pallet to be clamped at the full available pressure. The head 95 carries further clutch-actuating cylinders 98, 99 engaged by fixed pistons 103, 104, movement of the cylinders at a speed which is adjustable, causing actuation of upper or lower limit switches 110, 111 to denote whether the clutch is engaged or not and to control indexing. A rotary coupling 117 permits the clamping rod 59 to be held down while indexing movement of the table occurs. The table support 65 may be unscrewed from the base 22 and removed together with all the table actuating means. A mounting plate 151 on the support 65 carries a fluid motor to rotate the table through gearing 138, 134 and a set of cams as shown in Fig. 6. The fluid motor 150 rotates a shaft bearing cams 160, 161 once for every 45 degrees rotation of the table and a shaft 167, bearing cams 170- 173, which rotates with the table. When indexing movement of the table is started, switches 186, 187 are swung away from the cams 160, 161 by a solenoid 202 connected to a pivoted arm 188. When the switches 180-182 indicate that an indexed position is approached, the switches 186, 187 are released and are actuated by the cams to cause a slow approach to the final position by introducing a throttle valve into the exhaust line from the motor in addition to a valve for controlling the rapid rate of table movement. Hydraulic pressure is supplied by a pump 207, Fig. 16, driven by a motor 208 which also drives a compressor 344 supplying air through a line 345, Fig. 3, to clean the interengaging surfaces of the pins 45, 48 and of the clutch 67. When a pallet has been clamped by operation of a knob 366, an indexing cycle is commenced either clockwise or anti-clockwise by turning a switch 370 in the appropriate direction. The table is then indexed to the position set by a hand control 373 which controls the setting of six switches 375, 376, 377. The table then continues until the switches 180-182 are so actuated as to complete a circuit to a relay 380 which releases the solenoid 202 and allows the switches 186, 187 to be operated to slow and stop the table. The clutch 67 may be replaced by a series of four conical pins on the support 65 engaging any of eight recesses in the table. In a modification, a work-holder 425, Fig. 5, is clamped to the table 422 which is raised and lowered by a tubular piston 420 to disengage or engage clutch teeth 430, 435. The upward movement of the table is limited by the position of the hydraulic ports and, in its raised position, the table rotates on a cushion of fluid in a recess 442. This apparatus may be modified to have a pallet clamping means.