Cross-head die with volumetric flow compensation means

DETAILED DESCRIPTION The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 1.
A cross-head die for use in connection with an extruder to receive material from the extruder and direct the material into a downstream flow wherein the material is conformed to an annular configuration of desired wall thickness, said cross-head die comprising: a housing; an annular die passage extending axially within the housing, the die passage having an annular inlet, and an outlet axially downstream of the inlet; an input passage in the housing, the input passage extending transverse to the direction of the die passage for receiving the material from the extruder and passing the material toward the die passage; a manifold in the housing, the manifold communicating with the input passage and having an annular outlet juxtaposed with the annular inlet of the die passage, the manifold further having a given volume at locations along the manifold, the locations communicating with corresponding circumferential portions of the annular inlet of the die passage; and means operatively associated with the manifold for selectively varying the volume of the manifold at at least a first of said locations relative to a second of said locations to selectively adjust the relative flow rate of material from the manifold into the corresponding portions of the die passage, whereby the relative wall thickness is selectively adjusted about the periphery of the annular configuration.
2.
The invention of claim 1 wherein the manifold has an annular cross-sectional configuration and an axial length, and the means for selectively varying the volume of the manifold includes means operatively associated with the manifold for selectively varying the length of the manifold at said first location relative to the length at said second location.
3.
The invention of claim 2 wherein the manifold includes axially opposite annular first and second walls, the first wall being in fixed position within the housing and the second wall being selectively movable relative to the first wall such that the axial distance between the first and second walls may be changed at said first and second locations, and the annular outlet of the manifold is located in one of the first and second walls