| 摘要 |
PURPOSE:To prevent a screw head and a ring valve from wearing by a method wherein ceramic material for wear prevention is provided at the end surface on the screw head side of the ring valve or at the end surface on the ring valve side of the screw head. CONSTITUTION:A plasticizing screw 1 which is fittingly inserted in a heating cylinder so as to be freely rotated and reciprocated consists of a screw shaft part 2 and a screw head 3 which is mounted at the tip of the screw shaft part 2 and composed of a shell-shaped head main body 4 and a mounting part protrusively provided at the rear end surface of the head main body 4. Cylindrical ceramic materials 9, the end surface of each of which is exposed at the rear end surface of the head main body 4 so as to abut against the end surface of a ring valve 6, are imbedded in the head main body 4. The ceramic materials 9 are preferably arranged at equi-distant. Thus, even when the plasticizing screw rotates, either the screw head or the ring valve is prevented from wearing. |
