Patent GB-290607-A (GB)
Title: Improvements in and relating to boring and drilling machines
IPC: B23B39/16
Filed: 1927-11-18
Abstract: 290,607. National Automatic Tool Co., (Assignees of Galloway, R. M.). lay 16, 1927, [Convention date]. Drilling-machines; attachments for drilling. - A drilling-machine comprises one or more units, each embodying its own tool-rotating and feeding means, which may be mounted on a common base or support in any desired relation to the work and controlled in unison, and which may operate a single drill or a multiple-spindle head. Each unit V comprises a base 1, Fig. 1, carrying an electric motor M which drives a toolspindle S through toothed gearing 5 and a gear wheel 6 splined on the spindle. When a multiple head is used the spindle S is coupled to a gear wheel around which are arranged pinions on the tool-spindles the correct direction of rotation of the tools being obtained by any known means such as reversal of the motor M and the spindles being carried by a frame slidable on two guide rods attached to a stationary base. The spindle S carries two ball thrust bearings 45, 46, Fig. 2 between which is clamped by a nut 47, a plate 42 attached to a socket 40 pinned to the piston rod 11 of a fluid pressure cylinder 9, the piston rod causing the feed movements of the tool and being prevented from rotating by a bracket 48 slidable in a slot 49 of the frame 1a and attached to the socket 40. The flow of inelastic fluid, preferably oil, to the cylinder 9 is controlled by a valve V, the supply from a main to the valve being by a pipe 18 and from the valve to the respective ends of the cylinder by pipes 13, 14, the latter being connected to two pipes 19<a>, 20<a> which lead to large and small ports respectively in the valve thus providing for a rapid advance of the tool towards the work and a slow cutting feed. The valve comprises a hollow piston 17, Fig. 7, carried by a rod 24 and normally pressed to the left in this Figure by two springs 30, 31. A second piston 27 on the rod works in a cylinder 25 adapted to receive fluid, preferably air, under hand control to move the piston 17 to the right and a collar 29 on the rod slides through a hush 34 containing two L shaped stops 35, 36 which are pressed upwards by springs to snap behind the collar and prevent the return of the rod. In operation, with the tool in the inoperative position and the valve 17 in its extreme left position, air is admitted through a pipe 32 to the cylinder 25 to move the piston 27 against an annular stop 33, the piston 17 then admitting oil to both pipes 19<a>, 20a and advancing the tool rapidly to the work until a dog 51, adjustable on a slide 50 carried by the sliding bracker 48, depresses the stop 35 out of engagement with the collar 29 and allows the springs 30, 31 to return the collar against the stop 36. Oil then proceeds by the small pipe 20<a> only to the cylinder 9 and the tool is fed slowly through the work. On completion of the cutting operation a second adjustable dog 52 depresses the stop 36 and the piston 17 is returned to its extreme left position to admit oil through the pipe 13 and withdraw the tool rapidly, the rear end of the cylinder exhausting through the interior of the piston 17 and a pipe 23 leading to an oil sump. Should it be desired to return the tool to its inoperative position at any intermediate point, air is admitted through a pipe 56 to a vertically moving piston 55, Figs. 1 and 2, to depress both of the stops 35, 36 and allow the springs to return the piston 17. One or more of the units V may be mounted in any angular positions on a support and is shown in Fig. 4, four units are secured bv bolts 66, Figs. 1 and 2, to a table T which also supports the work W. A pump P, driven by a motor m, draws oil from a sump R and delivers it by a common pipe 65 to the separate supply pipes 18 for the valves V, the exhaust pipes 23 being connected by a pipe 67<x> to the sump, and a pressure relief 68 leading from the pump to the sump. A station O is provided for the operator and a control valve C. connected with an air pressure line 69, supplies air simultaneously to all the pipes 32 leading to the cylinders 25, and also, upon another manipulation, to the pipes 56 leading to the stop-releasing pistons 55. An electric power line is also provided for the motors M, with a separate switch for each motor. Should it be desired to raise any unit or incline it to the horizontal, packing blocks X, Fig. 1, may be inserted between the support T and the base 1 of the unit.