Examples of known molding systems are (amongst others): (i) the HYPET (TRADEMARK) Molding System, (ii) the QUADLOC (TRADEMARK) Molding System, (iii) the HYLECTRIC (TRADEMARK) Molding System, and (iv) the HYMET (TRADEMARK) Molding System, all manufactured by Husky Injection Molding Systems (Location: Canada).
U.S. Pat. No. 4,522,778 (Inventor: BACIU et al.; Published: 1985-06-11) discloses a method and apparatus for production of parts made from a plastics material using an injection press in which a mold cavity is defined by a mold surface and a surface of a movable piston. Firstly, the plastics material is introduced into the mold cavity, and during injection the piston is kept stationary for a time to form a rough mold and then retracted to form a parison. Secondly, after injection has been completed the piston is advanced again, and maintained in position while cooling takes place. Thirdly, the mold is opened and the part is ejected from the mold cavity.
European Patent Number 244783 (Inventor: MAUS et al.; Published: 1987-11-11) discloses a method and apparatus for injection compression molding of thermoplastic parts. Enlarged mold cavities receive plasticized resin, and compression of the injected resin is provided by a toggle clamp assembly. Preferably, the toggle clamp assembly provides multiple-stage compression of the resin to first redistribute the resin and vent the cavities and, second, compress the resin to compensate for cooling-induced shrinkage thereof. In the multiple cavities, because all cavities are equally compressed simultaneously, control of the molding process and balancing of the mold are readily accomplished.
European Patent Number 369009 (Inventor: UEHARA et al.; Published: 1990-05-23) discloses a desired quantity of a molten thermoplastic resin injected into a mold cavity which has a greater capacity than a product volume and is set in advance to a higher temperature than the temperature at which the thermoplastic resin starts curing under a normal pressure. The thermoplastic resin thus injected is cooled inside the mold cavity and is pressed before it is cooled down to a temperature at which it starts curing under a normal pressure. Due to this pressing, the glass transition point of the thermoplastic resin is shifted to a higher temperature side and the thermoplastic resin cures during a small temperature drop. The thermoplastic resin is cooled in the pressed state until dynamic rigidity at normal temperature and normal pressure is obtained. The thermoplastic resin is further cooled to a withdrawing temperature and the pressure applied to the thermoplastic resin is controlled so that dynamic rigidity of the thermoplastic resin during this cooling process can be maintained at the normal temperature and normal pressure by offsetting the rise of dynamic rigidity of the thermoplastic resin to be caused by cooling.
European Patent Number 425060 (Inventor: KASAI et al.; Published: 1991-05-02) discloses a process for effecting injection molding of plastic resin products on an injection molding apparatus including a metal mold composed of a slidable mold element and a fixed mold element defining together a mold cavity, an actuator for sliding the slidable mold element, and an injection means with an injection nozzle permissible of adjusting the nozzle flow path section. The operation includes: (i) a first molding step of injecting a molten resin into the mold cavity which has been preset by the slidable mold element so as to include a post-compression margin to be compressed afterwards in a second molding step, to effect the injection under a reduced molding pressure, while causing a temperature elevation and, thus, a viscosity reduction of the molten resin, until the mold cavity has been filled up, and (ii) a second molding step of compressing the resin so charged in the mold cavity by operating the slidable mold element to compress the charged resin to compensate said post-compression margin, so as to allow an effective pressing force to be imposed onto the charged resin within the mold cavity also after the mold gate has been sealed.
European Patent Number 593308 (Inventor: HENDRY; Published: 1994-04-20) discloses a mold apparatus and method to form a solid injection molded plastic part. The mold portions of the mold apparatus are closed, charges of molten thermoplastic and pressurized gas are sequentially injected into a mold cavity, and the mold portions are sequentially separated and closed. The pressurized gas forces the hot plastic away from one mold half and against the other mold half, and separation of the mold portions ensures uniform distribution of the pressurized gas behind the hot plastic, which pressure is maintained during cooling.
Depending on the application, the plastic completely packs the cavity, fills but does not pack the cavity, and the mating faces can be abutted or maintained partially separated when the mold portions close. A gas seal is formed by the plastic to prevent gas in the mold cavity from reaching the finished exterior surface of the part during shrinkage of the plastic.
European Patent Number 597108 (Inventor: MORIKITA; Published: 1994-05-18) discloses a localized pressurizing type injection molding machine for applying various processes to moldings during an injection-molding cycle; the injection molding machine can apply various processes to the moldings after the injection molding process.
European Patent Number 944466 (Inventor: HEHL; Published: 1999-09-29) discloses a process for manufacturing injection moldings in an injection molding machine for processing plasticized masses, in which a regulated subsequent pressure is applied by the injection molding unit. At least in the areas of the molding away from the sprue, the subsequent pressure is generated by a regulated volume alteration of the mold cavity. The subsequent pressure can be distributed during the subsequent pressure phase even in the case of complex moldings.
European Patent Number 1343621 (Inventor: WEINMANN; Published: 2003-09-17) discloses controlled correction of possible quantitative errors in the production of optical data supports. The cavity of the mold is only partially filled prior to the stamping phase. It is the subsequent stamping that is used to complete the filling process by moving one mold half. In the first phase of stamping or compressing the melt, the pressure is detected in defined positions of the molds or at a defined point in time and any deviation from a predetermined set pressure value is corrected by the immediate introduction of a movement change in the stamping process. By acting on the pressure conditions in the mold cavity, it is possible to influence the backflow before the sprue is set, in terms of a set weight value of the finished data support.
PCT Patent Application Number WO/2007/039766 (Inventor: CLARKE; Published: 2007-04-12) discloses a mold for mounting between relatively movable platens of an injection molding press for injection impact compression molding of an article. The mold comprises a cavity plate formed with a depression, a core plate having a projecting core at least part of the outer surface of which is cylindrical, and a closure plate movable relative to the core plate and the cavity plate, and a surface in sealing contact with the cylindrical outer surface of the core. A locking mechanism is provided to lock the closure plate relative to the cavity plate while permitting the core plate to move relative to the cavity plate.
U.S. Pat. No. 7,293,981 (Inventor: NIEWELS; Published: 2007-11-13) discloses a method and apparatus for compressing melt and/or compensating for melt shrinkage in an injection mold. The apparatus includes a cavity mold portion adjacent a cavity plate, a core mold portion adjacent a core plate, a mold cavity formed between the mold portions, and at least one piezo-ceramic actuator disposed between either or both of the core plate and the core mold portion and the cavity plate and the cavity mold portion. A controller may be connected to the at least one piezo-ceramic actuator to activate it, thereby causing the mold cavity volume to decrease, compressing the melt.
United States Patent Application Number 2008/0026239 (Inventor: BALBONI; Published: 2008-01-31) discloses a preform that is formed by an upper neck which maintains unchanged its form in the final object and a hollow body, joined to the neck. The method foresees the insertion, within a matrix cavity, of a metered body of polymeric material whose mass is metered according to a reference value, and the subsequent pressure insertion of a punch within the matrix cavity until it closes the mold's molding chamber, the punch conferring the shape to the inner surface of the preform and the matrix having an inner surface which confers the shape to the outer surface of the preform. In the molding of the preform, the error of the mass of the metered body with respect to the reference value is distributed in the hollow body, which undergoes a subsequent hot deformation until it achieves the final shape. In the mold, the matrix comprises at least one deformable wall whose inner surface defines at least part of the inner surface of the matrix part intended to give form to the hollow body of the preform, said deformable wall having, at least in part, a relatively thin thickness which permits it to be elastically deformed under the pressure of the polymeric material in the final preform molding step, thereby varying the thickness of the hollow body.