Inflation molding device

An inflation molding device comprising:

• a temperature sensor configured to measure a temperature of a bubble discharged from a die;
• a camera configured to capture an image of the bubble;
• and
• a processor configured to execute
• acquiring bubble shape data from the image of the bubble captured by the camera,
• calculating a strain (ϵ) and a strain rate ({dot over (ϵ)}) of the bubble based on the acquired bubble shape data,
• estimating one or more viscosity parameters of the bubble based on the calculated strain (ϵ), the calculated strain rate ({dot over (ϵ)}), and the measured temperature,
• receiving an input of a molding condition, and
• performing a simulation to calculate a shape or a stress of the bubble using the input molding condition and the estimated viscosity parameters,
• wherein the viscosity parameters are coefficients of a viscosity model equation representing a viscosity (η) of the bubble as a function of the strain (ϵ), the temperature, and the strain rate ({dot over (ϵ)}), and
• the viscosity parameters are the coefficients used as a multiplier, a divisor, or an exponent for the strain (ϵ), the temperature, or the strain rate ({dot over (ϵ)}) in the equation representing the viscosity (η).