Technical Details of BarrelStructural Geometry• The base body is made of high-strength forged steel with end flanges and dowel pin holes. Multiple barrel segments are bolted together. Standard single-segment lengths commonly available are 100, 160, 200 and 240 mm, which can be freely combined to achieve different overall length-to-diameter ratios. • Closed barrel: No windows, complete housing, used for melting and homogenizing sections. • Open barrel: Top / side windows machined on the barrel for main feeding, side feeding and vacuum devolatilization. Vacuum hoods, feeders and dam blocks can be fitted. • Lined barrel: A liner (closed liner / open liner, C-type split / monolithic liner) is press-fitted into the barrel inner bore by interference fit; the housing does not come into direct contact with materials. • Unlined nitrided barrel: No inner liner. The figure-eight cavity is machined directly on the barrel and the inner wall is nitrided for hardening. • Independent heating and cooling channels are integrated inside the barrel. Each barrel segment forms an independent temperature control zone. Precision of the center-to-center distance of the figure-eight bores is guaranteed internally to maintain proper meshing clearance of screws. Material Configuration (Base Material of Barrel Housing)• 42CrMo, 45# forged steel: Standard housing base material with high strength, torsion resistance and thermal deformation resistance. The housing itself does not require wear or corrosion resistance. • Wear and corrosion resistance are fully provided by the inner liner. Available liner materials: 38CrMoAlA, WR5, WR13 and nickel-base alloy. Manufacturing Process• Integral forging and quenching & tempering heat treatment. • CNC machining of flanges, locating shoulders and figure-eight cavities. • Heating and cooling channels are machined and hydrostatic leak test is performed. • Flatness and coaxiality of flanges are strictly controlled to ensure concentricity when assembling barrel segments and reduce misalignment wear. Process Parameter Characteristics• Maximum operating temperature: 350℃ • Melt pressure bearing: Pressure under conventional extrusion conditions • Temperature control: Independent heating and cooling for each barrel segment with zoned temperature regulation • Lined barrel: Permanent reuse of housing; only the inner liner needs replacement, low operation and maintenance cost • Unlined nitrided barrel: Good thermal conductivity without assembly clearance; the whole barrel segment must be scrapped once the inner wall is worn • Windows of open barrel can be equipped with dam blocks to restrain melt backflow and climbing | Functions of Barrel•Load bearing and cavity support for the whole machine: As the main equipment housing, it bears torque transmitted by screws, melt pressure and thermal stress. It accommodates the full screw assembly. Multiple barrel segments are spliced to realize the specified overall length-to-diameter ratio and form a complete extrusion process cavity. •Segmented independent heat exchange and temperature control: Each barrel segment is equipped with built-in heating and cooling channels for precise zoned temperature control, meeting temperature requirements of conveying, melting, mixing and devolatilization sections respectively and restraining local overheating and degradation of materials. •Enable feeding, side feeding and vacuum devolatilization processes: Windows of open barrels connect with feeding equipment and vacuum systems to realize main feeding, side addition of glass fiber / powder additives, and vacuum extraction of moisture, monomers and small-molecule volatiles. Closed barrels provide sealed cavities for compression, melting and pressure build-up. •Protect expensive equipment body and reduce maintenance cost: For lined barrels, wear is transferred to the liner. Materials directly contact the liner while the barrel housing is protected from wear and corrosion. Only the damaged liner needs replacement instead of the entire barrel segment. •Modular and flexible process combination: Standardized modular construction with flexible arrangement of closed and open barrels. Feeding positions, side feeding points and number of vacuum ports can be adjusted according to formulations to flexibly modify extrusion process layout. |
