Patent GB-508660-A (GB)
Title: An improved machine for drilling or boring holes
IPC: B23B39/16
Filed: 1938-12-23
Abstract: 508,660. Hydraulically - operated machine-tools. RALSTON, G. Dec. 23, 1938, No. 37430. [Class 69 (ii)] [Also in Group XXII] A boring or drilling machine has a number of tool heads adjustably mounted round a work-piece and supported by brackets, packing- pieces, &c. to suit the positions of the required holes in the work, hydraulic devices in each head for rotating and feeding a tool spindle therein, a motor-driven pump for supplying fluid to all the heads, means in the heads for adjusting the rate of feed and length of stroke of each individual spindle, and for reversing the feed at the end of each cutting stroke, and means operative when the last spindle to perform its work has been withdrawn to stop the motor. The machine comprises a base 1, Fig. 1, supporting the work 11, brackets 3, 4, packing-pieces 2, and 7-10 and angle brackets 6 for supporting the tool heads 12-21 in the required positions and at the required angles. The tool heads are supplied with fluid by flexible or other pipes 22-45 from a pump 46 driven through a change-speed gear-box 47 from an electric motor 49 controlled by a pushbutton and cut-out switch 50. Each tool head consists of a frame 12, Fig. 8, having a twodiameter cylinder 100, 101, containing a stepped sleeve 102, 103 in which is a hollow feed plunger 104. The tool spindle 68 is mounted by ball bearings 120, 121 in the plunger 104 and is rotated by sliding vane motors 111-114 operating in eccentric cylinders formed in a body 109 secured within the plunger 104. Fluid is fed to the motors from a chamber 139 by a non-rotary tube 122 sliding with the plunger 104 within a fixed sleeve 136. To commence operation of all tools simultaneously the motor 49 is started and fluid is supplied by the pump 46 to an inlet port 140, Fig. 8, in each head, whence it proceeds by a non-return valve 142 to acylinder 142a, thus depressing a plunger 144, and causing piston 145 to open passage 151 to the exhaust 150 and piston 146 to close passage 153 from passage 154. Fluid also flows through non- return valve 141 into passage 152 and then through the reversing valve 159 to passages 177, 198a, 199 and 215 to the annular cylinder 101 where it causes the plunger 104 together with the tool spindle 68, to be fed rapidly outwards. Fluid also flows, from passage 199 to a cylinder 210, raising a piston 208 against spring pressure and causing piston 204 to throttle the supply to cylinder 101 and piston 205 to open passage 214, for the supply to the motors 111-114, to passage 199. This causes the spindle to be rotated and the rate of feed to be reduced before the tool meets the work in order to reduce shock, the point at which the change takes place being determined by the time taken by the piston 208 to make its stroke, and this being adjusted by a needle valve 213 which allows the fluid above the piston 208 to escape to the exhaust passages 176, 150. The fluid below the plunger 104 exhausts by passages 220, 188, 176, 150, and when the piston 208 moves upwards, a piston 203 restricts this flow and finally shuts it off, thus stopping travel of the plunger. A piston 204 is also moved by piston 208 to open passage 216, leading from a cylinder 194 closed by a non-return valve 195, to passage 188 leading to the exhaust line 150 whereby fluid which was trapped under a piston 197 in the cylinder is allowed to escape and constantly-acting fluid pressure from 177 through passage 198a is allowed to act and depress pistons 197, 198 against a spring 196. An adjustable needle valve 217 is placed in passage 216 to vary the rate of movement of piston 197. As soon as piston 197 begins to move, a channel 219 in the face thereof allows a restricted flow from passage 221 to passage 186 and thence through 150 to exhaust, thus allowing plunger 104 to move slowly downwards until the tool engages the work. The duraton of this slow movement is determined by the setting of needle valve 217 and when the piston 197 has fully uncovered passage 221, the cylinder 100 may exhaust freely to allow the plunger 104 to move at cutting speed until the base of the plunger contacts with an annular flange 260 on the sleeve 102. The sleeve then moves with the plunger and expels fluid from the annular chamber 101a below the enlargement 103 on the sleeve through passages 256, 154 to a cylinder 158a below a differential piston 156, 156a, connection between passages 154, 153 having been stopped by movement of pistons 144, 147. Movement of piston 156 first compresses spring 157 and then contact of the piston with a step on a rod 164 raises the rod and a piston 159 thereon against a spring 162, and contact of a projection 163 on the rod engages the base of a sleeve 166 carrying annular pistons 165, 165a to raise these pistons also. This closes passage 177 from supply 152 and thus stops rotation and feed of the tool spindle 68 and opens passage 177 to 151. Pressure in the chamber 101a falls due to stoppage of the sleeve 102 and stops upward movement of piston 156 so that it may be depressed by the spring 157. The differential piston 156a during its upward movement draws fluid into a chamber 156b where it is trapped by a non- return valve 169 and the piston 202, so that downward movement of piston 156 will force upwards the rod 164, thus further raising the pistons 165, 165a and 159 and opening passage 182 to 152 to raise the plunger 104, exhaust from above the plunger taking place through passages 215, 199, 198a, 177 and 151. Upward movement of the plunger is limited by a fixed sleeve 134 and in this position the pressure of the fluid supplied below the plunger is relieved by a relief valve 180. The rod 164 in its uppermost position causes a contact 173 at the top thereof to close contacts 174, the contacts of all the tool heads in the machine being arranged in series and in the circuit of the cut-out 50 of the driving motor 49 so that the circuit will be completed when the last tool spindle has retracted. The motor will then stop and the fluid supply to each head at 140 will cease. The pistons 144 &c. will then be raised by spring 149 and pistons 208 &c. will be depressed by spring 209, the plunger 104 will be held in the retracted position and the differential pistons 159 &c. will fall. The piston 144 discharges the fluid above it through a small aperture 143 so that the other piston valves will have time to drain before the exhaust passage 150, 151 is closed by the piston 145. Adjustment of the length of stroke of each plunger 104 and spindle is effected by rotation of a hand-operated screw 252 threaded into a non-rotatable piston 251 in a cylinder 250. When no nuid is being supplied at 140, the space below piston 251 communicates by passages 255, 256 with the annular chamber 101a and by passages 255, 154, 153 with the space 100, whilst the space above piston 251 communicates by passages 198a, 199, 215 with the space 101 above the sleeve 102 so that movement of the piston will raise or lower the sleeve to vary the point at which the plunger 104 engages the flange 260 to stop the outward feed. A spring and solenoid actuated control valve is provided in the outlet from the pump 46 so that the whole fluid system is connected freely to reservoir as soon as the motor circuit is broken. The speed of rotation of all the tools is controlled by the gear-box 47 between the motor and pump.