Patent GB-423999-A (GB)
Title: Improvements in or relating to hydraulic drilling machines
IPC: B23B47/22
Filed: 1933-07-13
Abstract: 423,999. Hydraulic machines. VICKERS, Inc., 7752, Dubois Street, Detroit, Michigan, U.S.A.-(Assignees of Vickers, H. F., and Herman, K. R. ; 7752, Dubois Street, Detroit, Michigan, U.S.A.) July 13, 1933, No. 19788. Convention date, Jan. 27. [Class 69 (ii)] [See also Group XXII] In an hydraulic drilling - machine, or a control device adapted for attachment to a drilling - machine, the drill is fed by a hydraulic cylinder whereof the controlling valve is arranged to cause the drill to reciprocate in a series of strokes in cycles, each cycle consisting of a forward rapid advance to the work, a slow cutting feed, and a rapid retraction, accumulative stop means being provided and being controlled by the advance of the drill during one feed stroke to increase the length of the next rapid advance whereby the work will be drilled by a series of progressively advancing step feeds. Means are also provided for varying the lengths of the successive steps and for varying the speed of the cutting feed during the first and last steps. The drill 3, Fig. 3, is connected directly or otherwise to a piston rod 4 attached to a piston 5 moved in a cylinder 2 for feeding and withdrawing the drill, oil being supplied from a pressure line 10 and controlled by a 4-way reversing valve 16. To start a cycle of operations, a lever 8 on a valve 9 is moved from the dotted to the full line position whereby oil proceeds from the line 10 by pipe 11, valve 12, pipe 13, valve 14 and pipe 15 to the top of valve 16, thereby allowing pressure to proceed from the pipe 10, through valve 16 and pipe 41 to the top of cylinder 2. Exhaust from the bottom of cylinder 2 proceeds freely by pipe 18, valve 19 and pipe 20 to the valve 16, and thence to the exhaust line T, thus allowing the drill to be fed rapidly towards the work. When the drill is almost in contact with the work, a stop 22 on a rod 7 moving in unison with the drill engages a lever 25 connected to both valves 12 and 19, moving these valves to the position shown in Fig. 4. The exhaust from the cylinder 2 now passes by pipes 18, 28 to a speed controlling valve 29 which is of the kind described in Specification 399,609, and has a variable passage 67 controlled by a handle 68 to adjust the rate of flow through the valve to give the required drilling feed. From this valve the exhaust proceeds at a constant rate to a metering cylinder 37, depressing a piston 35 until a pipe 40 is exposed, whereupon oil flows from a chamber 34 in the cylinder through pipe 40 to the lower end of valve 16. This raises the valve and reverses the supply and exhaust of the cylinder 2 to effect rapid withdrawal of the drill to its original position, the exhaust passing freely through pipes 41, 42 to the exhaust line T. The stroke of the piston 35 may be adjusted by a hand-operated screw 39 to vary the amount of exhaust oil from the cylinder 2 which is allowed to pass before reversal takes place, and thus to vary the length of feed given to the drill at each step. Whilst the drilling feed is taking place, the stop 22, which is frictionally held on the rod 7, is in contact with a fixed stop 43 so that the stop is moved up the rod by the length of the feed step and consequently the drill may proceed further into the work by this amount on the succeeding step at the rapid approach rate, before the slow drilling feed is started. When the drill reaches its fully retracted position, a stop 44 fixed to the rod 7 engages the lever 25 and resets the valves 12, 19 for the next drilling step. When the full drilling depth has been attained, the last downward stroke of the drill brings a dog 45 attached to the rod 7 into contact with an extension 46 on the lever 8 whereby the valves 9, 47 are rotated together. This moves the valves 14 to the right, by admitting oil into the space 51, and simultaneously admits oil below the valve 16 by means of the pipe 53,. thus causing the drill to be rapidly retracted. The movement of the valve 14, however, renders the valve 12 inoperative so that the movement of this valve by the stop 44 does not start a downward feed again. In its right hand position, the valve 14 places a stop 52 in the path of the stop 22 so that during the last upward traverse the stop 22 is returned to its original position on the rod 7. Closure of the valve 47 prevents the escape of oil from the pipe 40 and through the check valve 32. To initiate another cycle, the valve lever 8 is operated by hand to move the valve 14 into the left hand position again, and to return the drill to inoperative position at any point of the cycle the lever 8 may be raised by hand. The fixed stop 43 may be adjusted to vary the distance between the commencement of the drilling feed in the downward stroke of any step and the contact of the drill with the work. In order to return the drill to the withdrawn position without otherwise interfering with the cycle, e.g. for clearing a drill which has become clogged with cuttings, a valve 75 may be operated by hand to admit oil from the main 10 to the lower end of the valve 16, whereby the drill will be reversed and the cycle will continue when the valve 75 is returned to normal. For varying the lengths of successive drilling steps, e.g. for commencing with a feed of an inch, following with a feed of half an inch, and then continuing with feeds of three sixteenth's of an inch until the full depth has been reached, a valve 76, Fig. 14, may be placed in the pipe 38 leading to the metering cylinder 37 and operated by recesses 77 of different lengths in the rod 7. When the valve is opposite a recess 77 it connects the pipe 38 to exhaust and prevents the cylinder 37 from filling, but when a projection on the rod meets the valve, the latter is closed and the cylinder 37 may function in the normal manner, to give the required step feeds. In order to reduce the rate of feed when the drill first enters the work and when it is breaking through, the speed controlling lever 68, Figs. 4 and 15, may be operated by a slidable rod 79 carrying a dog 80 fixed thereto and being engaged by a pivoted dog 81. Before the stop 45 has engaged the lever 46 for the last reversal, it meets the dog 80 and moves the valve 67 to reduce the rate of feed for breaking through. The rod 79 remains in this position during withdrawal of the drill and during the first part of the feed on the next workpiece, but during the first step feed the stop 44 on the rod 7 engages the dog 81 to raise the rod 79 and restore the feed to the normal rate. Withdrawal of the drill may be effected automatically when the cutting torque exceeds a predetermined amount by using a hydraulic motor 82, Fig. 3, to drive the drill and connecting the pressure side of the motor to the valve 16 so that when the pressure becomes excessive the valve will be operated to withdraw the drill. Instead of a single drill, a battery of drills may be controlled by the apparatus described.