INJECTION MOULDING PROCESS FOR MAKING LABORATORY TEST-TUBES AND MOULD TO BE USED IN THE MOULDING PROCESS THEREOF

摘要

Process for the injection moulding of plastic material for making laboratory test tubes comprising a step of prearranging at least one mould (1) which defines, by means of an external female element (10) and an internal male element (20), a forming chamber (2) for a test tube. The chamber (2) has a main longitudinal extension along a central axis X. The female element (10) includes a bottom portion (30) and a head portion (40) in which an inlet mouth (41) has been made for the male element (20). Furthermore, the process comprises a step of inserting the male element (20) inside the female element (10) along the central axis X, an injection step wherein the melted plastic material is introduced under pressure inside the forming chamber (2)through a plurality of injection points (60) made on the female element (10), a filling step, wherein the plastic material progressively fills the forming chamber (2) to obtain the test tube, an evacuation step of the air, simultaneous with the filling step, an extraction step of the male element (20) from the female element (10) and a step of removal of the test tube from mould (1). In the evacuation step the air contained in the forming chamber (2) progressively exits from mould (1) under the pressure of the melted plastic material through a multiplicity of slits (70) made on the female element (10) at different heights along the above-mentioned central axis X. The slits (70) have dimensions such as to allow the passage of the air and at the same time to block the emission of the melted plastic material from the forming chamber (2). The invention moreover concerns a mould usable in the moulding process.