Patent GB-592122-A (GB)
Title: Improvements in combined milling and drilling machines
IPC: B23B39/02
Filed: 1944-08-04
Abstract: 592,122. Milling and drilling machines. JACK & HEINTZ RESEARCH CORPORATION. Aug. 4, 1944, No. 14952. Convention date, July 29, 1943. [Class 83 (iii)] In a machine for performing a succession of machining operations, such as drilling and milling, on a work-piece, the too] spindles are arranged in two planes around the work and the latter is moved by a fluid pressure ram at right angles to the tool planes for moving it into alignment with the spindles, the hydraulic system for moving the work and axially fed spindles being electrically controlled to perform a cycle of operations. The machine consists of a frame 28, Fig. 2, carrying four radial drilling spindles 20 and four radial milling spindles 4, each spindle being driven by an individual electric motor 26 through a belt 30 or a drilling and a milling spindle could be driven from one motor. Each spindle 4 is mounted in stationary bearings 141 spaced by a sleeve 143 and an oil ring 145 dips into an oil well 144 to lubricate the bearings. Each spindle 20 is attached to rotate with a feeding piston 24 in a cylinder 23 so that the piston will engage the cylinder cover at the end of the cutting stroke to act as a brake and stop the spindle rotation when the motor 26 is switched off. The work 1 is secured by a clamping device 2 on the top of a ram 3 adjustably coupled at 7 to a hydraulic piston 8 movable in a cylinder 9 which is attached to the machine frame by pillars 9<1>. The machine is operated by the hydraulic circuit shown in Fig. 6, and in operation with a work-piece attached to the ram 3, a main switch is closed momentarily to energize electrical relays which start the motors driving spindles 4, illuminate a red signal to show that the machine is in operation and actuate a solenoid 52 controlling valve 64. This valve is drawn downwards to admit fluid from a pump by line 94 through a two-way check valve 66 to the top of cylinder 9 to force ram 3 downwards. Valve 64 also opens the bottom of cylinder 9 to an exhaust line 95 through an unrestricted line 81 and also through a bleed passage 82 and two-way check valve 67, thus allowing the work to be fed rapidly downwards until piston 8 closes port 13, after which the work is fed at cutting speed past the cutters 4<1>, this speed being determined by the bleed passage 82. When port 12 is covered by piston 8 at the end of the milling operation, the fall of pressure in passage 82 actuates a switch 53 to energize relays which stop the motors driving the spindles 4 and apply direct current to the fields of the motors to stop their rotation by dynamic braking. Fall of pressure in the exhaust line 72 also actuates a switch 54 which operates relays to de-energize solenoid 52 and allow a spring to return valve 64 upwardly and connect line 71 to supply and line 72 to exhaust. Piston 8 is then traversed rapidly upwards and check valve 66 maintains sufficient pressure in line 71 to prevent a switch 55 from closing until port 11 is covered by piston 8, whereupon the fall in pressure in line 71 actuates the switch to operate relays which energize a solenoid 62 acting on a valve 65. Movement of this valve admits fluid from supply line 92 through a two-way check valve 99 to a manifold 98 supplying the rear ends of cylinders 23 through lines 74, thereby feeding the drill spindles 20 to the work. Exhaust from cylinders 23 is directed by lines 77 and check valves 120 to a manifold 97 connected through a two-way check valve 100 and valve 65 to the exhaust line 93. Bleed passages 88 byepass the valves 120 to throttle the exhaust and give the required rate of feed to the drills. Rise of pressure in the manifold 98 operates a switch 56 to energize relays for starting the spindle motors for the drills, and on completion of the drilling operation the pistons 24 cover the exhaust ports 22 and pressure in manifold 97, which has been maintained by check valve 100, is reduced so that a switch 57 may close to actuate relays which stop the spindle motors. The spindles are brought to rest by pistons 24 engaging the cylinder covers. Simultaneously, solenoid 62 is de-energized and valve 65 reverses the flow in manifolds 97, 98 causing a rapid withdrawal of the drills at a speed determined by bleed passages 84. When ports 21 are covered by pistons 24, pressure in manifold 98, built up by check valve 99, drops, and switch 56 is thereby actuated to energize relays which illuminate a green signal to indicate that the machining operations are completed.