Patent GB-275676-A (GB)
Title: Improvements in and relating to milling, grinding, or abrading or like machines
IPC: B23B47/22
Filed: 1927-08-09
Abstract: 275,676. Cincinnati Milling Machine Co., (Assignees of Ernst, H.). Aug. 9, 1926, [Convention date]. Milling-machines.-In a milling-machine the work is moved relatively to the tool by fluid pressure at relatively high speed prior to engagement of work and tool, at a slow speed during cutting, and again rapidly after cutting in either forward or reverse direction for removal of the work or for a new cut to be made; the work also may be moved and reversed at desired speeds, means for stopping the work table also being provided. The invention is shown as applied to an automatic milling-machine comprising a bed A, a cutter D, and a reciprocable table F moved by a piston 11 in a cylinder 12, having fluid connections 13, 14. With the arrangement shown in Fig. 7, fluid is drawn by a constant discharge pump 17 from a reservoir 15 and passes through a multiple piston valve 21 - - 24 to the inlet 13, thus urging the piston 11 to the left, the rate of movement of the piston being controlled by a variable discharge pump 28 through which fluid passes from the left-hand side of the piston via pipe 14. If the rod 20 of the valve be moved partially to the left, fluid from the pump 17 may pass directly, through a coupling 31, to the pump 28, acting equally through pipes 32, 25 on opposite ends of the piston and arresting its movement. Further movement of the valve to the left enables fluid to pass to the pipe 14 from the pump 17, the pipe 13 being connected to the pump 28, so that a reversal of movement of the table F is obtained. A pressure release valve 26 is fitted to permit flow of fluid to the reservoir in the event of excessive pressure. Fig. 9 shows an arrangement for obtaining variable speeds, for example rapid traverse and feeding speeds in one or both directions, and comprises a constant discharge pump 35, a variable discharge pump 36, and three valve casings with valves 39, 76, 110 respectively therein. With valves 39, 76 in the position shown, fluid is admitted to the righthand end of the cylinder 49. moving the piston and the machine table to the left at a speed controlled by the pump 36. To obtain a rapid return of the piston, a second constant discharge pump 61 is employed, which is ineffective during the working stroke to the left, but when the valve 39 is moved to the right is connected to the lefthand end of the cylinder, the right-hand end of the cylinder being freely open to the reservoir 62. To move the work rapidly up to the tool, the valve 76 is employed, movement to the right allowing fluid from pump 61 to move the piston until the work has approached the tool and the valve 76 is moved to the left, when the slow cutting speed is resumed; the valves 39, 76 also allow of a slow return movement of the work. The valve 110 acts as a stop mechanism when moved to the right, by throwing the various fluid feeding lines into communication with one another. The valves may be arranged in a chest 95, Fig. 3, and moved by a plunger 102, which may be partially rotated by dogs 105, 106 on the table F adapted to engage a head 107 on the plunger, or may be moved vertically by a cam 108; a handle 109 also may be provided to operate the valves, and the valve 110 may be moved by a handle 112 and also by a dog on the table. In a further modification, adapted for use when auxiliary mechanisms are to be actuated, for example, spindle reversing and stopping mechanism, two variable discharge pumps are employed, the discharge of the main pump being controlled by a spring-pressed check valve which is connected to the discharge line of the pump, and, according to the pressure therein, varies the discharge; the spindle reverse is operated in timed relation to the reversal of the work table, and the spindle stop is operated if the pressure in the main line pipe falls unduly. The Specification as open to inspection under Sect. 91 (3) (a) comprises also an arrangement wherein the table is moved by fluid pressure and its speed is controlled by a screw, which engages a rotating nut. This subject-matter does not appear in the Specification as accepted.