JPS6111182B

PURPOSE:To improve plastic mix and temper efficiency by forming groove depth of material supply side and groove depth of material exit side of a screw groove of a screw for plastic molding apparatus in gradually increase and decrease repeatedly at a definite rate along screw notch. CONSTITUTION:In a screw 10 for plastic molding apparatus, groove depth of material supply side and groove depth of material exit depth of a screw groove 11 of the screw are formed in gradually increase and decrease repeatedly at a definite rate along screw notch 12 and at both ends of the screw groove, deep groove sections 14a, 14a' and shallow groove sections 13a, 13a' are formed alternatively in such manner that phase becomes exact reverse. Thus, in material feeding work by a screw 10, materials in the screw groove receives partial cutting action which acts when materials directly moves over the shallow groove section of both ends of the edge line and distributing and mixing action which acts when materials moves in depth direction of the screw groove as moves zigzag in addition to heating and mix and temper action so that mix and temper efficiency is greatly improved.