Patent GB-475791-A (GB)
Title: Improvements in and relating to hydraulically-operated drilling, mortising and like machine tools
IPC: B23B39/00
Filed: 1936-04-23
Abstract: 475,791. Drilling &c. machines. BROOKMAN, Ltd., R. S., and BROOKMAN, R. S. April 23, 1936, No. 11558. [Class 83 (iii)] [Also in Group XXIII] In a hydraulically-operated machine tool wherein a cutter-head and work-holder are reciprocated relatively to each other for the purpose of inserting the cutter into and extracting it from the work, a reversing valve for the hydraulic reciprocating mechanism is actuated by the head at opposite ends of the traverse and means including a variable orifice are provided for delaying the action of the reversing valve to cause the head to dwell in order that the work may be moved or changed. As applied to a mortising or drilling &c. machine, which may be similar to that described in Specification 403,620, a cutter-head 20 is moved on guides of a vertical column 22 by means of a hydraulic cylinder supplied from an accumulator through a hand-operated speed regulating device 70. The hydraulic circuit is controlled by a vertical rod 31 which is normally biassed to a lower non-operative position but may be raised by a pedal 52 to cause the head 20 to be fed downwards until a stop 46 thereon engages a dog 49 on the rod to depress it and stop the feed. Side motion of the pedal will then rotate the rod 31 to clear the stop 46 and allow the head to feed the tool through the work on the table 21 until a stop 45 on the head engages the dog 49 and again stops the feed. Release of the pedal allows the rod 31 to move downwards and reverse the feed, the head then moving 'upwards until the stop 46 engages the dog 49, after which the rod 31 may be rotated to allow the head to ascend further until arrested by a stop 47, or, alternatively, the pedal may be depressed again for another working feed. In order to make the head 20 reciprocate repeatedly, with or without a dwell in the upper position toallow movement of the work, the stop 46 is replaced by a shorter stop' 150 and a second control rod 151 carrying dogs 152 ... 154 is provided. The rod 151 is splined to a collar 155 provided with two holes spaced 90‹ apart, either of which may be engaged with a pin 159 on a lever 157 connected to a remote control so that by lifting the collar 155 the rod 151 may be rotated into a position where the dogs 152 &c. engage the stops on the head 20 for automatic control or into a position clear of the stops for control by the pedal 52, as shown in Fig. 3. The remote control is preferably electric and operates a solenoid 160 connected by linkage 162, 163 to a rod 164 pivoted to the lever 157 and by linkage 1631 to a valve 161 which controls admission of fluid from an accumulator to a valve 166 through passage 165. The valve 166 is connected by a lever 167 pivoted at 168 to the rod 151 and admits fluid to an adjustable needle valve 169. In operation, closing of the remote control switch energizes the solenoid 160 so as to rotate the rod 151 to position dog 152 under the stop 150 and open the valve 161 which thereupon admits fluid past the valve 166 to the needle valve 169. The fluid flows slowly past the needle and by passage 170 to a plunger 171 which is thereby raised against spring pressure until the needle is byepassed by a passage 172, thus admitting fluid rapidly to a plunger 174. This plunger is then raised, and through a lever 175 raises the rod 31 to admit fluid for a feeding stroke of the head 20. As the head descends the stop 150 engages a bevelled surface on the dog 152 and rotates the rod 151 against a spring 185 without affecting the control, and at the end of the working stroke the stop 45 engages the dog 153 to depress the rod 151. This cuts off fluid supply through valve 166 and opens the plungers 171, 174 to exhaust through passages 177, 178, the valve 166 having a rapid load-and-fire device 182. The rod 31 then descends, either by its own biassing means or by action of the stop 45 on the dog 49, and the motion of the head 20 is rapidly reversed. If a dwell is required at this end of the stroke, the cylinder 173 of plunger 174 could be arranged to exhaust through a needle valve similar to valve 169, or the plunger 171 could be made doubleacting. When the tool is clear of the work the dog 150 engages the under side of the stop 152 and the rod 151 is raised to admit fluid to plunger 174 for a reversal of feed, which is delayed until plunger 171 has been raised, the upward feed meanwhile having been stopped by upward movement of rod 31 through engagement of the dogs 154, 49. If continuous reciprocation without a dwell is required, the plunger 171 may be held in a raised position so as to byepass the needle valve 169 by means of a cam-operated stop 180. When the operator releases the remote control switch the valve 161 closes and the rod 151 is rotated to a position wherein the dog 152 is clear of the stop 150. Closing of the valve 161 opens plungers 171, 174 to exhaust through a passage 184, whereupon the head 20 moves to its uppermost position and the stop 47 engages both dogs 154, 49 to raise the rods 151, 31 and bring the head to rest. The control switch may be incorporated in one of the workholding jaws so that when a work-piece is inserted the head will descend and simultaneously the jaws will grip the work, as described in Specification 403,620. When the head dwells after the cutting operation, the work table may be moved laterally for a further operation, and after the required number of operations a master switch may be opened to stop the head in its upper position and release the jaws. The remote control may be pneumatic, hydraulic or mechanical instead of electric. Specification 363,020, [Group XXIII], also is referred to.