DOUBLE-SCREW EXTRUDER Russian patent published in 2006 - IPC B29C47/40 A23P1/12 

FIELD: plastic processing.

SUBSTANCE: double-screw extruder contains sectional housing with screws installed for engagement and rotation in opposite direction forming zones of charging, compression, metering and homogenization and having sections of intensive shift and distribution of product. Screw have screw of equal pitch and depth. Screw cuts in zones of charging, compression and metering have opposite directions. Screw cuts in zone of homogenization have same direction. Slots to pass crests of screw cut of other screw are made in crests of cut of one screws in direction opposite to direction of its screw cut. Screws are made in form of set of screw member fitted on core. Screws in zone of homogenization on intensive shift section consist of successively repeated screw members with screw cut of constant pitch and depth and provided with cuts with slots. Screws on product distribution section consists of screw members with screw cut of constant pitch and depth and plasticizing cams. Ratio of length of screw members on intensive shift section is found from formula m_i=L₂/L₁ where L₁ is length of screw member with reverse cut, m: L₂ is length of screw member of constant pitch and depth, m. Screw in zone of metering consists of screw members with screw cut of variable thickness and cylindrical-and-conical core. Proposed double-screw extruder is furnished with unit to produce multilayer products with filling, containing intermediate disk, die, channel former, filler, pre-die zone fairing and head. Filler consists of hollow disk with tube to fed filling material, and forming tube. Pre-die zone fairing is essentially truncated cone with holes to deliver product melt into channel former which forms, together with filler forming tube, a coaxial channel.

EFFECT: improved quality of product processing owing to intensification of clamping forces providing many times repeated shift deformation of extrudate melt, enlarged operating capabilities of extruder.

4 dwg