Patent GB-355739-A (GB)
Title: Improvements in or relating to metal milling or other machine tools
IPC: B23Q5/26
Filed: 1930-05-28
Abstract: 355,739. Milling &c. machines. WHITE, A. E., 5, Quality Court, Chancery Lane, London.-(Kearney & Trecker Corporation ; West Allis, Wisconsin, U.S.A.) May 28, 1930, No. 16455. [Class 83 (iii).] A metal-milling or other machine tool has a movable member operated by a fluid motor supplied by a pump which has an adjustable throttle in its suction pipe for controlling the speed of the movable member. The support 2 guided on the vertical column 1 carries a lower longitudinal slide 3 and an upper transverse slide 4. The spindle is driven from a power pulley 6 through a friction clutch 10, operated from a hand-lever 13, change speed gearing 21, countershaft 20 and gears 32, 33. The change speed mechanism which is operated from a hand-lever 28 comprises a sliding gear cluster 22, 23, 24 coacting with gears 25, 26, 27 on the countershaft. The cross slide 4 is fed by a fluid pressure cylinder 87, the piston-rod 89 of which is secured to the slide, the fluid being delivered by a low capacity feed pump 34 comprising intermeshing gears 36, 37, and by a high capacity quick traverse pump 35 comprising intermeshing gears 47, 48. The gears are mounted on parallel spindles 46, 51, the driving member 47 of the quick traverse pump being mounted on the spindle 51 which is driven from the pulley 6 through gears 53 and shafts 54, 57. The driving member of the slow feed pump is mounted on the shaft 46 which is driven from the shaft 11, Fig. 12, so that this pump is only operated when the spindle drive is in operation. The suction sides of both pumps are connected through a pipe 61 and passage 67 to a reservoir 58. In the case of the slow feed pump the intake passes first through a cut-off throttle 60 consisting of a plunger 65 and then through a feed control throttle consisting of a plunger 62 having a tapered end portion 63 which may be set to the desired rate of feed by means of a pointer 68 acting through gearing, Fig. 12, on the plunger 62. The flow to the quick traverse pump may be stopped by a cut-off throttle plunger 77 which is interconnected by a member 81 with the cut-off throttle 60 so that when one cut-off is closed by operation of a hand-lever 82, the other is simultaneously opened. The output of the slow feed pump is delivered through a passage 92 to ports 93, 94 of a reversing valve 85 and thence to the cylinder 87. The quick traverse pump also delivers fluid to the ports 93, 94 through a spring- loaded check valve 96. The upper part of valve stem 86 is cut away as shown in Fig. 9, while the lower part has a through passage which connects the port 94 with an exhaust passage 109 when the valve is in the Fig. 9 position. When the valve is turned to the position shown in Fig. 10A the pressure fluid passes through the passage 101 and pipe 103 to the left-hand end, Fig. 12, of the cylinder to move the table 4 to the right while exhaust fluid from the cylinder passes through passages 102, 100, 107, 108 through exhaust throttling devices to the reservoir. By shifting the valve 86 the movement is reversed. The exhaust throttling devices comprise a spring- loaded ball valve 110 which maintains a predetermined back pressure, and a plunger valve 114 which is normally held up by a spring 115 so as to close the exhaust passage 108. When pressure exists in the channel 92, fluid passes through a pipe 119 and lowers the plunger 114, thus bringing an aperture 120 in the plunger into alignment with the passage 108 and permitting exhaust fluid to flow to the valve 110. The reversing valve may be moved by a hand-lever 122 connected to the valve through a gear segment 124 and also arranged to operate vertical rack members 130, 131. When the lever 122 is moved to the left the valve is operated to cause the table to move to the left, Fig. 7, and the rack 130 is raised. At the end of the traverse, an adjustable dog 132 on the table engages the rack 130 and restores the parts to the position shown in Fig. 7, thus bringing the valve to its neutral position, Fig. 9, and stopping the table. The right-hand traverse may be similarly arrested by a dog 135 engaging the rack 131. The purpose of the exhaust throttling devices in the passage 108 is to prevent the table from overrunning its drive. If such a tendency occurs the pressure in the passage 92 will fall and the plunger 114 will be moved to check the flow from the exhaust side of the piston and prevent overrun. The ball valve 110 causes a small back pressure under all operating conditions which tends to eliminate chatter. A spring-ball relief valve 137 is provided in the delivery passage of the quick traverse pump and a similar valve 140 is provided in the delivery passage of the slow feed pump.