Patent GB-605055-A (GB)
Title: Improvements in or relating to machine tools
IPC: B23D7/00
Filed: 1945-06-25
Abstract: 605,055. Planing. ROCKFORD MACHINE TOOL CO. June 25, 1945, No. 16122. Convention date, Dec. 27, 1943. [Class 83 (iii)] (Also in Group XXXVII] A support or head for a machine tool, such as a planing-machine, is movable on the frame of a machine by the co-operation of a stationary part or screw on the frame with a part or nut driven by a wound rotor induction motor on the movable support, which motor may be operated as part of a self-synchronous system comprising also a generator which may be rotated in accordance with the movement of the reciprocating work-table of the machine so that a feed motion is imparted to the support once each cutting-stroke, or the motor may be run from a three-phase supply to give the support a traversing motion. Additional supports or heads may be actuated at the same time by connection of their motors to the generator. In Fig. 1, the planing-machine comprises a bed 10, carrying a table 11 reciprocated with quickreturn motion by the hydraulic cylinder and piston 31-32, Fig. 5, the upright columns 12 and 13, and the cross-rail 14 vertically movable on the columns by an electric motor 17 on the rail driving nuts on the fixed screws 15. Heads 25 are movable vertically by nuts, also on screws 15, driven by induction motors 26; other heads 25 are similarly movable along the rail 14 by nuts on the screw 18 fixed to the rail. A head 25 on the rail 14 is made up of a saddle 65, Fig. 4, the motor 26, a swivel 67 and a slide 68 movable by the hand-rotatable screw 83 passing through the rotatable nut 82 on the swivel. A dog-clutch member splined on the shaft 70 of motor 26 can be brought into driving engagement alternatively with a gear member 77 (which drives the nut 82 through bevel gearing) or a gear 75 (which drives the nut 76 on the screw 18) by a yoke 95 on the shaft 21 rockable by handle 22. For hand adjustment, the shafts 70 can be separately rotated by the shafts 19 through gears 74 and 74<SP>1</SP>. The hydraulic power is provided by a piston pump and gear pump combination 35 driven by an electric motor 60 and supplying the ends of the cylinder 32, Fig. 5, alternately through valve mechanism 36 actuated, through linkage 54-55-57, by dogs 59 on the table 11 so as to reverse the motion of the table automatically at each end of travel. Pressure when applied to cylinder 32 for the return stroke, is applied also to the left-hand end of a cylinder 106, Fig. 5, and when applied for the cutting-stroke is applied also to the right-hand end of the cylinder 106; the resulting movement of a hollow and rack-toothed piston in cylinder 106 actuates a pinion which drives, through a rollertype free-wheel clutch and further gearing, a generator 100 connected to one or more of the motors 26. The stroke of this piston can be adjusted by a stop-nut which travels from the lefthand end of the cylinder 106 on rotation, manually or by a reversible electric motor 119, of a screw which enters the hollow piston. The whole stroke is made during the initial part. of the cutting- stroke of table 11 whereby, before the work reaches the tool, a feed motion is given to the head 25 or its slide 68 by its motor 26 moving synchronously with the generator 100 through a distance determined by the stroke of device 106. The various motors 'are supplied from three-phase mains L1, L2, L3 and controlled by contactors energized through a step-down transformer T, Fig. 10. The hydraulic pump motor 60 is started by pressing push 182 to energize the coil PCC of the self-maintaining pump contactor PCS ( and the indicator 184) and is stopped by push 183. The height of rail 14 is adjusted by motor 17 which is started (up or down) by holding down push 185 or 186 to energize temporarily the coil UCC or DCC of the up-contactor UCS or the down-contactor DCS through the switch LS1 closed by the coil CC of the contactor CS (closed by the same pushes) which energizes a coil C to unclamp the rail ; coil UCC is also subject to an up-limit switch LS2. The stroke of device 106 and hence the feed is adjusted by holding down one of the pushes 190 or 191 to energize temporarily one or other of the field windings 188 and 189 and the armature 187 of the motor 119. The generator 100 is single-phase excited by pressing push 192 to energize the coil CC of the self-maintaining contactor GS which can be de-energized by pressing stop-push 193. Each motor 26 has a set of switch-gear as enclosed in dotted lines in Fig. 10. To operate the machine, with automatic intermittent feeding of a head 25 or its slide 68, the clutch member 90 is engaged with one wheel or the other and the appropriate selector switches 161 and 162 are put in the left-hand position to energize the feed relay FR; forward or reverse push-button 195 or 196 is then pressed to energize the coils MC and RC or MRC and RRC of the stator and rotor contactors MS and RS or MRS and RRS to give suitable excitation of motor 26 and to interconnect the rotors of motor and generator. These contactors are maintained through contacts of the relay FR. Release of the push prepares a circuit for the coil MTC. The start and stop valve 61 on the control valve 36 is operated to cause the table 11 to reciprocate and the generator 100 to oscillate; the hydraulic pressure opens switch PS1-the relay FR, however, maintaining itself and the stator and rotor contactors-and closes switch PS2 to complete the circuit of coils MTC and CRC, thereby closing contactors MTS and GRS to connect the third phase of the motor and the generator. respectively to supply main L3. The feeding is stopped by opening the selector switches. Traversing, to bring the tool up to or away from the work, is effected by moving the selector switches to the right to energize coils TC and ITC and pressing push 195 or 196 to energize temporarily the coil MC or MRC, so that contactor ITS completes the circuit of the rotor and contactors TS and MS or MRS connect the supply to the stator of motor 26 for operating it as an ordinary induction motor, this traversing being subject to the hydraulic pressure being cut off and switch PS1 closed.