METHOD FOR ESTIMATING RELATIONSHIP AMONG EXTRUSION AMOUNT, PRESSURE DIFFERENCE, SCREW ROTATING SPEED AND FILLING LENGTH IN SCREW CHANNEL OF BIAXIAL SCREW EXTRUDER, AND METHOD FOR DESIGNING SCALE-UP OF SCREW OF THE EXTRUDER

PROBLEM TO BE SOLVED: To efficiently design an extruder having similar extrusion characteristics by deciding sizes of respective parts based on a specific formula obtained by nondimensionalizing a distance between design and theoretical shafts, a gap between designed shafts, a design gap between a barrel and a screw, a groove depth, a reduction amount of the gap between the shafts at the time of a designed highest temperature and a gap between the actual shafts at the time of using temperature. SOLUTION: Dimensions of respective parts are obtained from next nondimensionalized formula obtained by dividing a distance CL between designed shafts between screws, a distance CL deg. between theoretical shafts, a groove depth H of a screw 1, a radial gap δ between an inner diameter DB of a barrel 2 and an outer diameter DS of the screw, a gap α between a designed shafts between the screws, a gap reduced amount between the shafts at the time of a designed highest temperature, and a gap ω between axial shafts at the time of a using temperature by outer diameter DS, where DB is the inner diameter of the barrel 2, DS is an outer diameter of the screw 1. Formulae CL'=CL' deg.+α'+δ'=1-H'+α'+δ', '=CL'.β(T-T deg.), ω'=ω/DS=δ'+α'- '=δ'+(n-1) '>=δ', and n>=1. β is a thermal expansion coefficient of the screw.