초록 ▼

A method for controlling certain parameters of an injection molding cycle applying PVT optimization wherein the injection pressure and injection velocity of the melt are utilized to calculate an average viscosity for the melt during injection in a qualifying cycle of the machine as well as subsequen

A method for controlling certain parameters of an injection molding cycle applying PVT optimization wherein the injection pressure and injection velocity of the melt are utilized to calculate an average viscosity for the melt during injection in a qualifying cycle of the machine as well as subsequent production cycles. A ratio of the average viscosity in a given cycle relative to the viscosity in either the qualifying cycle or a preceding cycle is utilized to adjust the holding time and cooling time, thereby achieving PVT optimization. In a second aspect, an injection molding machine is utilized to develop PVT constants for a given material by pressurizing the material in the barrel against the blocked outlet nozzle, measuring the volume during pressurization, and then weighing the pressurized shot after it is purged from the barrel in order to calculate the specific volume of the material. Plotting specific volume against a variety of pressure and temperature values produces a plot of PVT relationships from which the constants can be derived.

대표청구항 ▼

A method of controlling certain parameters of an injection molding cycle applying PVT optimization wherein the molding cycle comprises plasticating a material by means of a rotating screw, injecting a shot of the plasticated material into a closed mold by axially advancing the screw, applying holdin

A method of controlling certain parameters of an injection molding cycle applying PVT optimization wherein the molding cycle comprises plasticating a material by means of a rotating screw, injecting a shot of the plasticated material into a closed mold by axially advancing the screw, applying holding pressure on the material in the mold for a holding period, permitting the molded part to cool in the closed mold, and then opening the mold at the end of the cooling period, said control method comprising: performing at least one qualifying molding cycle to produce a first part having acceptable quality wherein the qualifying cycle holding period and cooling period have respective selective lengths, in the qualifying cycle, measuring the injection velocity and injection pressure at at least one selected axial position of the screw during injection, calculating the viscosity of the plasticated material as a function of the measured injection velocity and pressure, performing a subsequent second molding cycle to produce a second part, measuring the injection velocity and injection pressure during said second cycle at said selected position of the screw, calculating the viscosity of the plasticated material in the second cycle as a function of said measured injection velocity and pressure in the second cycle, and adjusting the holding period time and cooling period time in the second cycle in proportion to the ratio of said calculated viscosities in the qualifying and second cycles.