| 摘要 |
PURPOSE:To perform smooth and stable continuous coating with a screw extruder by specifying the ratio of the shaft diameters of the screw in a feed zone and a constant volume feeding zone for the flux as well as the ratio between the shaft diameter and the outside diameter of a screw blade respectively. CONSTITUTION:A screw 1 which consists of a shaft 1a and a blade 1b and constitutes a feed zone (a), a compression zone (b) and a constant volume feeding zone (c) for a flux F is provided in a cylinder 2 to increase stepwise the degree of compression of the flux F. A core wire 6 inserted in a die block 3 through a nipple 5 is extruded together with the flux F from a die 4 thereby forming a coated arc welding rod. The ratio d1/d2 between the shaft diameter d1 of the screw in the zone (a) and the shaft diameter d2 of the screw in the zone (c) of said screw 1 is set at 0.7-0.9 and the ratio d1/D between the shaft diameter d1 of the screw in the zone (a) and the outside diameter D of the screw blade is set at 0.4-0.8, and the ratio d2/D between the diameter d2 of the screw in the zone (c) and the outside diameter D of the screw blade is set at 0.6-0.8. |
