| 摘要 |
<p>The method for realizing the screw spiral of the invention comprises the phases of: preparing a die (10) suitable for casting plastic materials, comprising a tubular core (11) provided with a central cavity (1) and having an internal surface (2) and exhibiting a channel (3) extending spirally and coaxially to the core (11), wherein the central cavity (1) and the channel (3) in combination give rise to a moulding cavity (4) of said die (10); insertion in the central cavity (1) of the core (11) of a metal stalk (6) twisted about itself in such a way as to obtain a spiral shape therefrom spiralling in a direction which is opposite to a direction of the spiral of the channel (3) and held in a coaxial position to said core (11); filling of the moulding cavity (4) with a molten plastic material in order to obtain after solidification thereof a screw (5) containing the stalk (6) embedded in a centre thereof; extraction of said screw (5) from said moulding cavity (4). <IMAGE></p> |
