Vacuum sizing apparatus

Claim 1

In a vacuum sizing apparatus of the type having: (a) a structure defining an elongate through passage, the structure being adapted to be positioned downstream from an extruder with the passage extending along a path followed by a deformable body of settable material being extruded substantially continuously from the extruder; (b) the structure having inner wall portions which define at least a part of the passage and which present a passage cross section unto which outer surface portions of the extruded body are to be conformed as the body travels through the passage; (c) the inner wall portions being provided with a plurality of vacuum evacuation openings through which gases may be evacuated from the passage to form a vacuum therein in the vicinities of the inner wall portions for causing outer surface portions of the extruded body to be brought into conforming engagement with the inner wall portions to thereby conform outer surface portions of the body to the passage cross section defined by the inner wall portions as the body travels through the passage; the improvement wherein: (a) the structure comprises a plurality of structural segments arranged in side-by-side relationship, with adjacent ones of the segments having side walls extending in surface-to-surface mating engagement, and with the segments having inner walls extending substantially contigiously to define the inner wall portions of the passage; (b) the vacuum evacuation openings being located at the junctures of the side walls and the inner walls, and each of the evacuation openings forming the inner end of a separate vacuum evacuation channel; (c) the vacuum evacuation channels being formed, at least in part, by grooves machined in selected ones of the mating side walls of adjacent ones of the structural segments; (d) conduit means interconnecting the channels and communicating the channels with a vacuum source for evacuating the passage in the vicinities of the regions where the vacuum evacuation channels open through the inner wall portions to bring outer surface portions of the body into conforming engagement with the inner wall portions as the body passes through the passage; and, (e) clamping means releasably clamping the segments together to form a rigid structure with the inner walls defining smooth and contigiously extending inner wall portions which are imporous except for the vacuum evacuation openings which open through the inner wall portions.