摘要:
An injection moulding apparatus has a mould tool that is positioned around a field joint of a pipeline to define a mould cavity. Two or more pumping chambers communicate with the mould tool. Each chamber is expansible to draw in molten polymer and contractible to drive the polymer into the mould cavity. Expansion of one chamber is synchronised with contraction of another chamber. The operation of supply and injection valves associated with the chambers is also synchronised, both with each other and with expansion and contraction of the chambers. In the embodiment described, two pumping chambers are defined within a common pressurising cylinder, in which the chambers are separated by a piston. The piston is movable within the cylinder to determine and to synchronise expansion and contraction of the chambers.
摘要:
Torques and resin pressures applied to a screw are detected during the forward movement of the screw and coefficients of correlation between the detected torques and resin pressures are calculated. When the check ring is open, the flight of the screw receives resin pressure, and the screw torque increases proportionally to the resin pressure due to resin backflow, so the coefficients of correlation between the screw torques and the resin pressures are higher than a reference value. When the check ring closes, the flight of the screw no longer receive resin pressure, so the screw torque decreases and the coefficients of correlation become lower than the reference value. The check ring is determined to be closed when the coefficients of correlation become lower than the reference value.
摘要:
There is provided a method (300) of controlling melt pressure at a filter outlet (113) of a melt filter (112) in an injection unit (100) having an extruder (102) that is connectable to a melt accumulator (122) via the melt filter (112), the melt filter (112) being associated with a target melt pressure range, the method executable at a controller (126) associated with the injection unit (100), the method (300) comprising: appreciating (310) an indication of an actual melt pressure associated with the melt filter (112); responsive to the actual melt pressure not being within the target melt pressure range, determining (320) a remedial parameter that is instrumental in bringing the actual melt pressure within the target melt pressure range; releasing (330) a control signal to execute an action associated with the remedial parameter, thereby causing the actual melt pressure to fall within the target melt pressure range.
摘要:
There is provided a method (300) of controlling melt pressure at a filter outlet (113) of a melt filter (112) in an injection unit (100) having an extruder (102) that is connectable to a melt accumulator (122) via the melt filter (112), the melt filter (112) being associated with a target melt pressure range, the method executable at a controller (126) associated with the injection unit (100), the method (300) comprising: appreciating (310) an indication of an actual melt pressure associated with the melt filter (112); responsive to the actual melt pressure not being within the target melt pressure range, determining (320) a remedial parameter that is instrumental in bringing the actual melt pressure within the target melt pressure range; releasing (330) a control signal to execute an action associated with the remedial parameter, thereby causing the actual melt pressure to fall within the target melt pressure range.
摘要:
A system and method for the injection moulding of plastic material through a plurality of injectors each having a pin valve displaceable in a controlled fashion between a closing position and an opening position by a respective actuator of an electronic control type, in which there is provided prompt activation of a preset function of changing a colour of the plastic material to be injected, actuated according to an optimized sequence which minimizes a number of moulding operations required to change the colour.
摘要:
Torques and resin pressures applied to a screw are detected during the forward movement of the screw and coefficients of correlation between the detected torques and resin pressures are calculated. When the check ring is open, the flight of the screw receives resin pressure, and the screw torque increases proportionally to the resin pressure due to resin backflow, so the coefficients of correlation between the screw torques and the resin pressures are higher than a reference value. When the check ring closes, the flight of the screw no longer receive resin pressure, so the screw torque decreases and the coefficients of correlation become lower than the reference value. The check ring is determined to be closed when the coefficients of correlation become lower than the reference value.