Abstract: An injector for a plastic material injection molding apparatus whose cylindrical pin-shaped valve that is axially displaceable between an advanced fully closed position and a retracted position of maximum opening, is provided in proximity to a distal end thereof with a reduced diameter cylindrical portion which delimits with the outlet end of the tip of the nozzle terminal an annular passage having a constant cross-section. When the pin valve is between fully closed and maximum opening positions, the reduced diameter cylindrical portion can be selectively positioned in intermediate positions so as to vary the axial extension of the annular passage to adjust the pressure drop of the injected plastic material.

Abstract: Injection molding of plastic materials by an apparatus comprising at least one injector including a valve pin displaceable in a controlled manner between a closed position and an open position by an electric rotary actuator. At least one step is provided of detecting the value of the torque developed by the electric rotary actuator when the valve pin is in the path from the closed position to the open position, and the torque value detected is used to pilot the molding process.

Abstract: An injector for a plastic material injection molding apparatus whose cylindrical pin-shaped valve that is axially displaceable between an advanced fully closed position and a retracted position of maximum opening, is provided in proximity to a distal end thereof with a reduced diameter cylindrical portion which delimits with the outlet end of the tip of the nozzle terminal an annular passage having a constant cross-section. When the pin valve is between fully closed and maximum opening positions, the reduced diameter cylindrical portion can be selectively positioned in intermediate positions so as to vary the axial extension of the annular passage to adjust the pressure drop of the injected plastic material.

Abstract: A molding apparatus for the production of articles molded through sequential injection includes a mold having a cavity, a plurality of electrically actuated injectors arranged at central, intermediate and end positions, respectively, with respect to the mold cavity, and an electronic system for controlling the injectors for the actuation thereof according to a sequential cycle which provides for opening the central injector first, followed by the intermediate injectors and then the end injectors. The electronic control system is configured so that the opening sequential cycle occurs in such a way to obtain more linear and homogeneous pressure in the mold filling step, and lower packing pressure.

Abstract: A method of injection molding of plastic materials into a cavity of a mold with a molding apparatus including a distributor of the pressurized fluid plastic material connected to at least one injector having a pin valve displaceable between a fully closed position and an open position. The method includes a filling step following displacement of the pin valve from the fully closed position to the open position, a packing step of the pressurized plastic material keeping the pin valve in the open position, and a step of displacement and maintenance of the pin valve in at least one partially closed intermediate position prior to its complete closure.

Abstract: An apparatus for injection molding of plastic materials includes an injection machine platen, a mold including a backing plate for securing the mold to the injection machine platen, a distributor of the plastic material to be injected adjacent to the backing plate and bearing at least one injector including a nozzle within which a pin valve is axially movable, and a respective electric actuator with associated transmission to operate the displacement of the pin valve between a closed position and an open position. The transmission includes a variable-length connecting rod.

Abstract: To improve the flow symmetry and the molding quality, it is presented a valve pin bushing for the hot runner of an injection mold, including two input channels, each having a geometric axis and through which the material to be injected can enter through an outlet into, and an output channel, which extends along a longitudinal axis up to an output from which the material can exit the valve pin bushing. The portions of the geometric axes, which extend at the outlet are arranged so that on any imaginary plane passing through the longitudinal axis there lies at most one portion.

Abstract: An injection molding apparatus of plastic material including a mold, a fixing plate of the mold, a distributor of the plastic material to be injected and a plurality of injectors connected to the distributor and each including a valve pin controlled by a respective rotary electric motor and a transmission. The fixing plate has a cavity facing the mold on a first face, within which the distributor is contained, and each electric motor with the relative transmission is housed, in a quickly insertable and removable manner, within a respective seat arranged on a second face of the fixing plate opposite to the first face, laterally with respect to the corresponding injector.

Abstract: A nozzle terminal for injectors of injection molding apparatus of plastic materials, includes an inner tubular body or tip defining a flow passage for injected plastic material, and an outer ring coaxial with the tip. The tip includes a radially inner element made of a first material and a radially outer element made of a second material, and arranged in contact with a substantial axial portion of the radially inner element up to the distal end thereof, and mechanically coupled thereto.

Abstract: Apparatus for injection-moulding of plastic materials comprising a hot runner (1), at least one injector (2) including a nozzle mobile within which is a valve pin (3) driven by a rotary electric motor (4) and an associated transmission including a screw-and-nut assembly (10) for converting the rotation of the shaft (5) of the electric motor (4) into a translation of the valve pin (3). At least the rotary electric motor (4), and the screw-and-nut assembly (10) are set parallel alongside one another.

Abstract: To improve the flow symmetry and the molding quality, it is presented a valve pin bushing for the hot runner of an injection mold, including two input channels, each having a geometric axis and through which the material to be injected can enter through an outlet into, and an output channel, which extends along a longitudinal axis up to an output from which the material can exit the valve pin bushing. The portions of the geometric axes, which extend at the outlet are arranged so that on any imaginary plane passing through the longitudinal axis there lies at most one portion.

Abstract: Described herein is a process for the production of plates made of transparent plastic material with non-transparent overmoulded parts by means of a first direct injection and subsequent compression for the formation of the transparent plate, and a second injection for overmoulding said parts on the transparent plate, covering the indicators or witness marks of the first injection. Each injection can be in spots controlled in sequence, and the second injection can be followed by a respective step of post-compression.

Abstract: An injector for injection moulding of plastic materials incorporates a vacuum device for creating a suction pressure within the mould in an area corresponding to the injection point, prior to the injection of the plastic material.

Abstract: Described herein is injecto-compression moulding of articles made of plastic material with two components by means of a press of the stack-mould type in which the moulding cavity of the second component is maintained in a position of partial opening during the injection and compression of the first component within the first moulding cavity. There is moreover provided a retention system, which is associated to at least one of said first and second cavities.

Abstract: An apparatus and a process for the molding of articles made of plastic material with two components by means of a stack-mold press with a first cavity and a second cavity for the injection of the plastic material and the possible compression of the injected plastic material, in which the moulds and the countermolds of the apparatus define respective mutually facing surfaces. Parameters indicating the mutual parallelism between said facing surfaces are detected, and the closing assembly for closing the press is controlled according to the parameters detected.

Abstract: An auxiliary supporting structure for presses, having an auxiliary mold platen having a front surface designed to firmly, but removably, support a half-mold; a number of hydraulic supporting cylinders, which project from the rear of the auxiliary mold platen, in a direction parallel to a reference axis perpendicular to the plane of the auxiliary mold platen; mounting means for firmly, but removably, fixing the hydraulic cylinders to the front surface of a movable mold platen of the press; a hydraulic distributor for regulating pressurized-oil flow to and from each hydraulic cylinder independently of the others; and an electronic central control unit for controlling the hydraulic distributor as a function of signals from a number of external sensors, to enable the hydraulic cylinders to instantaneously compensate any asymmetric distribution of the mechanical forces exerted on the half-mold as the plastic material is injected.

Abstract: An injector for injection-moulding of plastic materials including a generally cylindrical body, wound on the outside of which are at least two pairs of mutually independent electrical heating resistors and associated to which are respective control thermocouples.

Abstract: Described herein is a process for the production of plates made of plastic material by means of sequential injection with the mould half-open and a subsequent step of compression obtained by closing the mould.

Abstract: Described herein is a process for the production of articles made of plastic material, in particular transparent plates, with parts made of plastic material at least in part overmolded on The plate by means of injection-compression, excluding from the compression areas of connection between the overmolded parts and the plate.

Abstract: Described herein is injection-compression moulding of articles made of plastic material with two components by means of a press of the stack-mould type, in which the first and second countermoulds are constrained to the corresponding moulds carried by the rotating central element of the press so as to enable the respective cavities to set themselves in a position of partial opening for the injection of the plastic material within them. To both of the cavities there is then applied a closing force to bring about compression of the plastic material injected therein.