Extrusion apparatus for producing large scale products

Claim 1

Apparatus for extruding large cross-section articles, comprising; heated extruder means for melting and initially pumping extrudant at a predetermined temperature compatible with the plastic flow thereof, and at a relatively low pressure; an extrusion die member enlarged to an extremely large scale and greatly expanded width-extrusion producing capability, and incorporating a rear heated die section having a relatively elongated, main, common, extrudant-collecting chamber in open communication with a plurality of extrudent-admitting, entrance passages open at, and evenly distributed over the rear end of said die member; a first series of relatively short extrusion passages in communication with, and extending forwardly of said collecting chamber and utilizable to transfer the extrudant forwardly in a molten state, and a second series of relatively elongated, extrusion passages communicating with the forward ends of said first-named series of passages for gradually cooling and thereby hardening the extrudant into the finished product, as it is transferred thereby further forwardly to and out of the forward or front side of said die member; a separate, heated, temporary extrudant-storage means disposed in spaced relation from the rear of the die member and in direct alignment with the open rear end of an extrudant-admitting, entrance passage corresponding thereto; an extrudant-exhaust outlet pipe extending from said extruder means; a main, common, extrudant-feed line in open communication with and receiving extrudant being pumped at relatively low pressure from said extruder means; a first series of extrudant transferring-branch lines respectively disposed between one end of each of said temporary extrudant-storage means, in communication with the interior thereof, and an extrudant-admitting, entrance passage of said rear die section corresponding thereto; a second series of extrudant transferringbranch lines respectively interconnected between said main, common extrudant-feed line and a selected one of said first series of bRanch lines corresponding thereto; said extruder means initially pumping molten extrudant at relatively low pressure through and completely filling said main, common, extrudant-feed line, and each of said first and second series of extrudant transferring-branch lines, the first series of entrance passages incorporated in said rear die section, the main, common, extrudant-collecting chamber thereof and the second series of extrusion cooling and hardening-passages; back pressure-producing means adjustably positioned to a first, rearwardmost location in blocking position against, and preventing further movement to the front of the gradually hardening extrudant being initially pumped at relatively low pressure by said extruder means into said second series of extrudant transferring-branch lines; and separate power-actuated means interconnected with and utilizable for each of said separate, temporary extrudant-storage means for thereby pressurizing and pumping the extrudant contained therewithin into the main, common collecting chamber at the rear of the die member, through the said first and second series of branch lines and entrance passages, and thereafter into the said second series of extrusion-cooling and hardening passageways, at a relatively high pressure sufficient to counteract the blocking effect of said back pressure-producing means for its subsequent extrusion into a relatively large scale item at the front of said die member.