Nanjing GIANT Machinery Co.,Ltd.

An apparatus for treating material fed therein and comprising a housing having two congruent bores extending through said housing, an inlet extending through said housing and into at least one of said congruent bores, a pair of non-intermeshing parallel or tangential, co or counter rotating twin screws, each disposed within one of said bores, means connected operably to said screws for turning said screws, said screws having flow restricting means disposed on each of said screws, said bores having a nip region, said nip region being defined by the ratio of the width between a pair of imaginary parallel lines, said lines being parallel to a plane defined by the center lines of the bores, one of which imaginary lines would touch the top of the nip and the other of which would touch the bottom of the nip, divided by the bore diameter, said ratio being equal to or less than 0.38 and being coextensive with at least a portion of the length of said flow restricting means, and an outlet in said apparatus for discharging material fed to and worked in said apparatus; the apparatus being such that a higher back pressure is created in the section of the single screw extruderimmediately preceding the section of the extruder having the nip ratio of equal.

Multi-bore extrusion apparatus wherein adjacent bores are inter-connected by a longitudinal nip between the bores and wherein screws located within the bores are provided with flow restricting means for delimiting upstream sections of relatively high pressure from downstream sections of relatively low pressure, characterised in that the dimensions of the nip, at least in a part of the length coextensive with the flow restricting means.

In an apparatus for working a material, usually referred to as a sheet production extruder, the extruder may be of the type wherein twin, co or counter rotating non-intermeshing screws are disposed within a barrel bore. The extruder is generally divided into sections or zones for the performance of different operations. For example, there is a feed section wherein material fed into the extruder is conveyed into a second section which may be a mixing section or a section wherein a reaction takes place. Sectioning is generally achieved, especially in those instances which require zones of differing pressures, by the placement of flow restriction means between the zones. Many times, it is necessary to have the reaction section under a positive pressure in order to promote the reaction of materials.

Thereafter, the reacted materials are passed to an area of lower pressure wherein undesirable liquids and volatiles are released from the reaction mixture. The construction of conventional twin screw extruder is such that between the barrel bores, wherein the screws are placed, there is a channel or opening which is usually in the form of a longitudinal slot, formed by the absence of a dividing wall between the bores.