Method for injection molding of thermoplastic pole parts, and mold for producing the same
View Patent ↗A method for injection molding of thermoplastic pole parts utilizes a mold to fix at least one vacuum interrupter and contact terminals during a molding process. At least one injection opening or gate for injection of thermoplastic material is formed into the mold. The mold is applied with multiple injection openings at least along its long axis, for injection of hot thermoplastic material, and the injection openings or gates can be steered in such a way that they inject thermoplastic material simultaneously or with a defined time dependent injection pattern. This process alleviates the issue of a pressure gradient along the long axis of the molded pole part, shortens process times, and achieves a homogenous dissipation of material during the molding process.
1. A method for injection molding of thermoplastic pole parts, the method comprising:
utilizing a mold to fix at least one vacuum interrupter and contact terminals during a molding process;
providing the mold with multiple injection openings at least along its long axis, for injection of hot thermoplastic material;
positioning at least one of the injection openings behind one of the contact terminals, the injected hot thermoplastic material exerting force against the contact terminal to push the contact terminal away from the injection opening and into a final end position;
positioning at least one of the injection openings along a surface of the mold transverse from the long axis;
wherein the multiple openings are provided with different hot thermoplastic materials, in order to implement a two or more compound molding during one molding process, one of the hot thermoplastic materials being filled with particles or fibres;
injecting the hot thermoplastic material filled with particles or fibres into the mold through at least one of the injection openings to strengthen at least one region of the pole part;
positioning the injection openings along the long axis such that they inject the hot thermoplastic material with a defined time dependent injection pattern;
providing the injection openings along the long axis with shutters, by which a flux of injected hot thermoplastic material can independently be steered for each injection opening;
measuring pressure in at least one of the injection openings and locations near to the injection openings along the long axis by pressure sensors to steer the injection of each injection opening such that the thermoplastic flows through the multiple injection openings are steered along a continuous pressure gradient from opening to opening; and
injecting the hot thermoplastic material at a previous opening sooner and with a same pressure than a following opening and so on, such that an injection pressure reaches an equal level of pressure along the multiple injection openings.
2. The method according to claim 1 , comprising:
locating further injection openings at points in the mold having a non-flat topography.
3. The method according to claim 1 , wherein that the thermoplastic flows through the injection openings are steered via at least one of the shutters and a pressure applied in at least one of the injection openings, gates and locations near to the injection openings and gates such that a direction of material flow in the mold during the molding process can be steered.
4. The method according to claim 1 , comprising:
operating the injection of the hot thermoplastic material by at least partly using film injection gates from the inner or outer side of the produced thermoplastic part.