| 摘要 |
A method for injection molding plastic molded parts from thermoplastic, comprises the following steps: the production of a thermoplastic melt (1) through the rotation of a plasticizing and injection screw (2) in a preplasticizing cylinder (3); the addition to the thermoplastic melt (1) of a fluid (4) by introducing the fluid (4) into the preplasticizing cylinder (3); the mixing up the thermoplastic melt (1) to which the fluid (4) has been added, through the rotational motion of the plasticizing and injection screw (2); the injection of the mixture of thermoplastic melt (1) and fluid (4) into the cavity (8) of an injection molding tool (5). In order to make this method suitable especially for the reliable and reproducible production of large, foamed plastic molded parts, the invention is characterized in that the mixture of thermoplastic melt (1) and fluid (4) is injected into the cavity (8) of an injection molding tool (5) through the translational motion of the plasticizing and injection screw (2), the fluid (4) is introduced into the preplasticizing cylinder (3) at an axial position (6) where the screw channels (7) of the plasticizing and injection screw (2) are situated at least some of the time, and the pressure difference (delta p) between the pressure (PF) of the fluid (4) and the pressure (ps) in the thermoplastic melt (1) is maintained essentially constant while the fluid (4) is being introduced into the preplasticizing cylinder.
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