Upstream nozzle sensor for injection molding apparatus and methods of use

An injection molding apparatus, comprising:

• a mold comprising one or more mold cavities;
• a ram arranged to form a shot of molten thermoplastic material;
• a strain gauge nozzle adapter including a strain gauge pin attached between the ram and a nozzle arranged to inject the shot of molten thermoplastic material into the mold cavities;
• a controller communicatively connected to the ram and nozzle and the strain gauge pin;
• and
• a virtual cavity sensor, implemented as a set of instructions that are stored on a non-transitory machine-readable medium, to determine at least one of an approximate pressure or melt flow front location using an output of the strain gauge pin, wherein the injection molding apparatus adjusts an operation of the ram in view of the determined approximate pressure or melt flow front location.

A method of injection molding, comprising:

• measuring, using a strain gauge pin, the change in strain in a strain gauge nozzle adapter;
• approximating at least one of a pressure or a melt flow front location within the mold cavity based on the change in strain;
• comparing the approximated pressure or melt flow front location to a trigger point;
• and,
• if the approximated pressure or melt flow front location equals or exceeds the trigger point, activating a virtual cavity sensor, wherein upon activation, the virtual cavity sensor causes a controller to perform an action.

An injection molding apparatus, comprising:

• a mold comprising one or more mold cavities;
• a ram arranged to form a shot of molten thermoplastic material;
• a strain gauge feed system adapter including a strain gauge pin attached between the nozzle and the mold;
• a controller communicatively connected to the ram and nozzle and the strain gauge pin;
• and
• a virtual cavity sensor, implemented as a set of instructions that are stored on a non-transitory machine-readable medium, to determine at least one of an approximate pressure or melt flow front location using an output of the strain gauge pin, wherein the injection molding apparatus adjusts an operation of the ram in view of the determined approximate pressure or melt flow front location.

A method of injection molding, comprising:

• measuring, using a strain gauge pin, the change in strain in a strain gauge feed system adapter;
• approximating at least one of a pressure or a melt flow front location within the mold cavity based on the change in strain;
• comparing the approximated pressure or melt flow front location to a trigger point;
• and,
• if the approximated pressure or melt flow front location equals or exceeds the trigger point, activating a virtual cavity sensor, wherein upon activation, the virtual cavity sensor causes a controller to perform an action.