Electro-hydraulic system for converting a lathe to automatic threading operation

Claim 1

IN A METAL CUTTING LATHE HAVING A BED, MEANS FOR ROTATINGLY MOUNTING A WORKPIECE PARALLEL TO THE BED AND A POWER UNIT FOR ROTATING THE WORKPIECE, THE COMBINATION INCLUDING: A CARRIAGE DISPOSED FOR LONGITUDINAL RECIPROCATION ALONG THE BED PARALLEL TO THE MAIN AXIS OF THE WORKPIECE; A TOOL BLOCK CARRIED BY SAID CARRIAGE FOR MANUAL LATERAL DISPLACEMENT AND PROVIDED WITH A BASE; A CARRIER SLIDINGLY MOUNTED ON SAID BASE FOR LATERAL DISPLACEMENT BETWEEN A RETRACTED POSITION AND A VARIABLE CUTTING POSITION, A TOOL CARRIED BY SAID CARRIER SO AS TO CUT INTO THE WORKPIECE WHEN APPLIED THEREAGAINST BY SAID CARRIER WHEN IN THE CUTTING POSITION, A LEAD SCREW ROTATED BY THE POWER UNIT; A HALF-NUT DEVICE ACTUATABLE FOR SELECTIVELY ENGAGING SAID CARRIAGE TO SAID LEAD SCREW FOR PASSING SAID CARRIAGE IN A LEAD DIRECTION FROM A START POSITION ALONG THE WORKPIECE; MEANS FOR ACTUATING SAID HALF-NUT DEVICE INTO AND OUT OF ENGAGEMENT WITH SAID LEAD SCREW INCLUDING A PINION GEAR AND A COOPERATING RACK DISPOSED FOR TRANSLATIONAL RECIPROCATION ON SAID CARRIAGE, A FIRST HYDRAULICALLY ENERGIZED PISTON CONNECTED TO SAID CARRIAGE TO EFFECT THE RETURN THEREOF COUNTER TO THE LEAD DIRECTION TO THE START POSITION; A SECOND HYDRAULICALLY ENERGIZED PISTON CONNECTED TO SAID CARRIER TO EFFECT ACTUATION THEREOF BETWEEN THE RETRACTED POSITION AND THE CUTTING POSITION AND FOR PRESSING SAID TOOL AGAINST THE WORKPIECE WHEN SAID CARRIER IS IN THE CUTTING POSITION SO AS TO CUT INTO THE WORKPIECE, A THIRD HYDRAULICALLY ENERGIZED PISTON CONNECTED TO SAID RACK TO EFFECT ACTUATION THEREOF FOR DISPLACEMENT OF SAID HALF-NUT DEVICE INTO AND OUT OF MESHING ENGAGEMENT WITH SAID LEAD SCREW, SOLENOID ACTUATED VALVES RESPECTIVELY DISPOSED IN COOPERATION WITH SAID FIRST, SECOND, AND THIRD PISTONS FOR CONTROLLING THE APPLICATION OF HYDRAULIC ENERGY THERETO, A TIMING DEVICE CARRIED BY SAID CARRIAGE AND GEARED TO SAID LEAD SCREW FOR ROTATION THEREBY, LIMIT SWITCHES RESPECTIVELY ARRANGED FOR ACTUATION BY SAID CARRIAGE, CARRIER, AND RACK AT THE OPPOSITE LIMITS OF DISPLACEMENT THEREOF AND BY SAID TIMING DEVICE WHEN SAID LEAD SCREW AND SAID HALF-NUT DEVICE ARE RELATED FOR MESHING ENGAGEMENT, A CAM-CLUTCH DEVICE OPERATIONALLY INTERPOSED BETWEEN SAID CARRIER AND SAID TOOL BLOCK FOR ADVANCING THE CUTTING POSITION OF SAID CARRIER CLOSER TO THE WORKPIECE IN PREDETERMINED INCREMENTS OF DISPLACEMENT BY CYCLIC DISPLACEMENT OF SAID CARRIER; COOPERATING MEANS ON SAID CAM-CLUTCH DEVICE AND ON SAID CARRIER FOR ADJUSTING IN A CONTINUOUS RANGE THE INCREMENTS OF DISPLACEMENT OF THE CUTTING POSITION OF SAID CARRIER, AN ELECTRIC CIRCUIT ELECTRICALLY INTERCONNECTING SAID SOLENOID ACTUATED VALVES, SAID TIMING DEVICE AND SAID LIMIT SWITCHES FOR REPEATINGLY AND AUTOMATICALLY ACTUATING SAID CARRIAGE, CARRIER, AND HALF-NUT DEVICE IN CYCLIC SEQUENCES TO WHERE SAID TOOL CUTS INTO THE WORKPIECE A PREDETERMINED DEPTH WHEN THE ELECTRIC CIRCUIT IS ENERGIZED.