Continuous extrusion apparatus

Claim 1

Continuous extrusion apparatus having a rotatable wheel formed with two identical circumferential grooves, arcuate tooling with portions bounding radially outer portions of the respective grooves provided with exit apertures extending in a generally radial direction from the respective grooves to a single chamber and abutments displaced in the direction of rotation from the apertures extending into the grooves, characterized in that the exit apertures extend through a die top from the respective grooves to a substantially toroidal chamber around a portal mandrel discharging a tubular extrusion product axially of the mandrel through a die orifice of uninterrupted annular cross-section intermediate the mandrel and a die body wall, a tubular shroud comprising a forward portion, an intermediate portion and a rear end portion, the intermediate portion having an increased wall thickness in relation to the wall thickness of both the forward portion and the rear end portion and being positioned internally co-axially of the mandrel and formed with alternating axially extending lands and grooves, the lands seating on the interior of the mandrel and the grooves providing a plurality of parallel cooling fluid flow passages, an outer sleeve extending co-axially externally of the rear end portion of the shroud and having an internal diameter equal the internal diameter of the mandrel secured to a rear end portion of the mandrel to form a first cylindrical passage intermediate the outer sleeve and the shroud, a spigot secured to the end of the outer sleeve by a fluid tight joint remote from the mandrel and seating in the arcuate tooling, the spigot being formed with a cooling fluid inlet tapping communicating with the said first cylindrical passage, the forward portion of the shroud extending internally co-axially of, and radially spaced from, a portion of the hollow portal mandrel adjacent and beyond the extrusion orifice and around a continuous core member supplied to the extrusion orifice respectively to form a second cylindrical passage intermediate the tubular extruded product and the forward portion of the shroud and a third cylindrical passage intermediate the forward portion of the shroud and the continuous core member, the said third cylindrical passage extending rearwardly intermediate the intermediate portion of the shroud and the continuous core member and intermediate the rear end portion of the shroud and the continuous core member to a cooling fluid exit at a rear face of the spigot, thereby forming a cooling fluid path extending from the cooling fluid inlet tapping through the first cylindrical passage, the grooves in the intermediate portion of the shroud, the second passage and the third passage to the cooling fluid exit, and swaging means positioned forwardly of the forward end of the shroud arranged to swage down the tubular extrusion product on to the continuous core member.