Patent EP-2514579-A1 (EP)
Inventor: BOUCHERON GILLES
IPC: B29C45/26
Filed: 2012-04-05
Abstract: The device comprises a molding assembly (10), and a bell (12) intended to maintain the molding assembly under vacuum. The molding assembly has a stack of molding plates according to a stacking axis (AA'). Each of the molding plates has two parallel principal faces including an upper principal face (Fi) and a lower principal face (Fs). Passages between the upper principal face and the lower principal face are a row of the passage in a range of 1-K. The molding plates are slide relative to each other in a plane of main faces to be placed in an injection position under vacuum. The device comprises a molding assembly (10), and a bell (12) intended to maintain the molding assembly under vacuum. The molding assembly has a stack of molding plates according to a stacking axis (AA'). Each of the molding plates has two parallel principal faces including an upper principal face (Fi) and a lower principal face (Fs). Passages between the upper principal face and the lower principal face are a row of the passage in a range of 1-K. The molding plates are slide relative to each other in a plane of main faces to be placed in a injection position under vacuum, where the passages are aligned to form conduits intended to be filled together by the polymerizable material or in a closed position such that the passages of the plates containing the polymerizable material considered to be closed on one side by the lower face of the mold plate in front and the other side by the upper face of the plate according to the stack forming cavities of the passages containing polymerizable material. The stack of molding plates is enclosed between a distribution plate (30) in the passages under vacuum and a vent plate (70) to facilitate the obtaining of the vacuum in the passages. The vent plate includes vent holes such that, in a vacuum position in the mold assembly, the vent holes are aligned with the passages of molding plates to facilitate the achievement of a vacuum in the passages of the molding plates before the injection of the polymerizable material. The distribution plate comprises injection channels distributed such that, in the injection position under vacuum, the vent holes are aligned with passages of molding plates in order to inject the polymerizable material under vacuum. The molding plate of the stack of includes sub-plates, which are stacked to form the passages of the molding plate. The passages are in the form of concave, convex, taper, and have rectangular and cylindrical shapes with a revolution axis. The sub-plates have passages to form frustum-shaped chamfers on the molded elements. The molding plate comprises two half shells for molding a polymerizable material component. The two half-shells comprise two edges partially present in contact to carry out a passage between the two half shells for the polymerizable material. The passages are configured to form protuberances in the body of the molded element having a section, in a perpendicular plane, in the form of semi-spherical, truncated, rectangular, triangular or other desired forms. Each of the molding plates is longitudinally guided in a plane parallel with its principal faces in order to produce a slip of the plate. The bell has circular cylindrical shape with an external diameter (D1), and comprises a bell end portion and a side bell portion. A side of the bell end portion has a through-hole in the interior of the bell. A wall of the bell end portion comprises, inside the bell, a circular plane surface with a diameter (D2) having a conical opening until a diameter (D3) on a height (H3) inside the bell. The conical opening is connected to a circular cylindrical opening with diameter (D4) that is larger than the D3 of the conical opening to form a flange of the plate. The circular cylindrical opening is connected by another flange of the bell with diameter (D5) that is higher than the D4 of the circular cylindrical opening and is lower than the D1 of the bell to form a wall of side of the bell. The wall of the side bell portion comprises a groove emerging with an interior of the bell containing a joint of plate present in contact with a circular side edge of the distribution plate to carry out the sealing compared to the external medium between the molding assembly and the bell. An insert of the bell end portion has a flat head and a cylindrical body having, in the revolution axis, a threaded hole emerging into the interior of the bell, is held by a nut in the through hole of the bell end portion such that a lower surface of the head of the insert abuts the circular flat surface of the bottom wall of the bell, and comprises a central thrust screwed in the threaded hole of the insert of bell end portion. The main faces of the molding plates are covered with an antifriction coating with to facilitate the slip one of the molding plates compared to the other of the plates. An independent claim is included for a method for molding collective elements made of polymerizable material.