Measuring device and measuring method for an injection molding machine for ascertaining a batch-specific characteristic number

An injection molding system, comprising:

• a plasticizing unit;
• a tool;
• and
• a measuring device, the measuring device including a flow channel for situating between the plasticizing unit and the tool, a first pressure sensor situated along the flow channel, a second pressure sensor situated along the flow channel, a first temperature sensor situated along the flow channel, and a second temperature sensor situated along the flow channel, wherein the flow channel has a taper between the first pressure sensor and the second pressure sensor.

A measuring method for ascertaining a batch-specific characteristic number of a plasticized plastic, while plastic flows through a flow channel, which is situated between a plasticizing unit and a tool, the flow channel having a taper, during an injection molding operation, the method comprising:

• carrying out a first measurement during a first injection molding operation, in which first measured data of a first pressure sensor provided along the flow channel and first measured data of a second pressure sensor provided along the flow channel are detected during a first measurement interval having a first lower measuring time and a first upper measuring time;
• forwarding the first measured data of the first measurement to a first evaluation module and to a second evaluation module;
• calculating a second measurement interval in the first evaluation module at a second, lower measuring time and at a second, upper measuring time;
• ascertaining a first batch-specific characteristic number in the second evaluation module;
• storing the first lower and upper measuring times and the first batch-specific characteristic number;
• and
• carrying out a second measurement during a second injection molding operation, in which second measured data of the first pressure sensor and of the second pressure sensor are detected during the second measurement interval.