| 摘要 |
PURPOSE:To manufacture a molding with a stable quality by combining a changeover valve, a cleaning piston and a bypass passage to clean up an injection nozzle maintaining a pressure balance in the switching of the injection over to the circulation of a resin and vice versa. CONSTITUTION:When a resin is injected, a cleaning piston 40 is set to the injection position at which injection ports 15 and 16 are opened and resin components are injected into a mixing chamber 11 from injection nozzles 30 and 31 to mix. Upon the completion of the injection, three-way ball valves 20 and 21 are turned and the resin components fed into return outflow sections 17 and 18 through return side nozzles 32 and 33 to be circulated to components tanks 8 and 9. At this point, the cleaning pistion 40 advances through the mixing chamber 11 to discharge mixed components. If the injection nozzles 30 and 31 are to be cleaned, the three-way ball valves 20 and 21 are switched over to the injection nozzles 30 and 31 and turned to let the resin components to a bypass passage for cleaning. |
