Apparatus for the extrusion pressing of tubes, especially steel tubes

Claim 1

IN AN APPARATUS FOR CONVERTING AXIALLY PERFORATED BILLETS INTO TUBES BY EXTRUSION PRESSING, IN COMBINATION, (A) ELONGATED PRESSURE CHAMBER MEANS OPEN AT ONE END AND ADAPTED TO ACCOMMODATE AN AXIALLY PERFORATED BILLET; (B) DIE MEANS HAVING A DIE OPENING DETERMINING THE OUTER CONTOUR AND DIMENSIONS OF A TUBE TO BE EXTRUDED; (C) TOOL HOLDER MEAN CARRYING SAID DIE MEANS AND BEING MOVABLE BETWEEN AN IDLE POSITION AND AN OPERATIVE POSITION IN WHICH IT SUBSTANTIALLY CLOSES SAID ONE OPEN END OF SAID PRESSURE CHAMMBER MEANS AND PLACES SAID DIE MEANS IN OPERATIVE POSITION; (D) RAM MEANS IN SAID PRESSURE CHAMBER MEANS AND MOVABLE THEREIN IN LONGITUDINAL DIRECTION FOR FORCING THE MATERIAL OF A BILLET LODGED IN SAID PRESSURE CHAMBER MEANS THROUGH SAID DIE MEANS WHEN THE LATTER ARE LOCATED BY SAID TOOL H OLDER MEANS IN SAID OPERATIVE POSITION; (E) GUIDE TUBE MEANS ARRANGED STATIONARILY IN SAID PRESSURE CHAMBER MEANS COAXIALLY WITH SAID DIE OPENING WHEN SAID DIE MEANS ARE IN SAID OPERATIVE POSITION, AND EXTENDING LONGITUDINALLY THROUGH SAID RAM MEANS AND THROUGH AN AXIALLY PERFORATED BILLETS WHEN THE LATTER IS PLACED IN SAID CHAMBER MEANS, SAID GUIDE TUBE MEANS HAVING A FORWARD FREE END SPACED AXIALLY A PREDETEREMINED DISTANCE FROM SAID DIE MEANS AND SHAPED TO FORM TOGETHER WITH THE FACE THEREOF OPPOSITE THERETO AN ADMISSION FUNNEL FOR THE MATERIAL OF SAID BILLET TO BE FORCED THROUGH SAID DIE OPENING; AND (F) MANDREL ROD MEANS ARRANGED TO BE FREELY SLIDABLE THROUGH SAID GUIDE TUBE MEANS ANND EXTENDING THROUGH SAID DIE OPENING SO AS TO DETERMINE THE INSIDE CONTOUR AND DIMENSIONN OF THE TUBE TO BE EXTRUDED, SAID MANDREL ROD MEANS COMPRISING AT LEAST TWO SECTIONS INTRODUCIBLE AT THE REAR END OF SAID GUIDE TUBE MEANS DURING THE EXTRUSION OPERATION, AND A SLEEVE COUPLING SAID SECTIONS TOGETHER AND HAVING AN OUTER DIAMETER CORRESPONDING TO THE OUTER DIAMETER OF SAID MANDREL ROD SECTIONS, WITH AN ANNULAR GROOVE WITH SHARPLY DEFINED EDGES PROVIDED IN THE AREA OF SAID SLEEVE WHEREBY THE MANDREL ROD MEANS ARE CARRIED ALONG CONTINUOUSLY BY A TUBE BEING EXTRUDED AND AIN CONTINUOUS STATIONARY COINTACT WITH THE INNER SURFACE THEREOF SO AS TO PREVENT DETERIORATION OF SAID INNER SURFACE BY CONTACT WITH ATMOSPHERIC AIR DURING THE COOLING OFF PERIOD FOLLOWING THE PASSAGE THROUGH THE DIE MEANS AND A CONSTRICTION MARK IS CAUSED TO APPEAR ON THE EXTRUDED TUBE IN THE AREA OF SAID SLEEVE THEREIN.