Injection molding machines and methods for accounting for changes in material properties during injection molding runs
AssigneeImflux Inc.
InventorsGene Michael Altonen, Kimberly Nichole McConnell, Vincent Sean Breidenbach, Milko Georgiev Gergov
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Abstract
A method and a machine that account for changes in material properties of molten plastic material during an injection run. If viscosity of the molten plastic material changes during an injection run, a controller alters a step time of the injection cycle to ensure that molten plastic material completely fills and packs a mold cavity to prevent part flaws such as short shots or flashing.
Claims18
A method of automatically adjusting a step time for an injection molding cycle in an injection molding run to adapt for variations in the flowability of a molten plastic material, the method comprising:
- (a) during a first molding cycle of an injection molding run, injecting a first shot of molten plastic material into a mold cavity and removing injection pressure from the first shot of molten plastic material so that the first molding cycle has a first step time wherein the step time is the time from initiation of injection of molten plastic material to just before the mold is opened for ejection;
- (b) during the first molding cycle, measuring a first time for the molten plastic material to reach a flow front sensor that is configured to sense the presence of a flow front of the molten plastic material at a particular location in the mold cavity;
- (c) a first comparing of the first time to a predetermined time to determine a first comparison result;
- (d) determining a second step time, based, at least in part, on the first comparison result;
- and
- (e) during a second molding cycle of the injection molding run, subsequent to the first molding cycle, injecting a second shot of molten plastic material into the mold cavity and removing injection pressure from the second shot of molten plastic material so that the second molding cycle has the second step time.
Dependencies are inferred from the claim text.