| 摘要 |
An extrusion die for externally annularly ribbed seamless plastic tubing has an elongated nozzle within which a hollow mandrel is placed. The nozzle and mandrel define an annular extrusion orifice for extrusion of a parison. The orifice has a coaxial conical portion with its generatrix forming an angle of more than 45 DEG with the longitudinal axis of the nozzle for efficient filling of mold cavities corresponding to annular ribs of the formed tube. The diameter of the inner conical portion at its delivery end may be at least that of the outer portion.
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