Method and installation for measuring the glass distribution in containers

A method for measuring a distribution of a thickness of glass in glass containers (2) at a high temperature leaving shaping cavities (4), the method applying at least one sensor sensitive to infrared radiation (6) emitted by the containers (2) suitable for producing an image of a distribution of the infrared radiation, characterized in that the containers pass in translation direction (D) in front of at least said sensor sensitive to the infrared radiation (6) and in front of at least one contactless point-like thickness measurement system (11) and in that the method includes for each container the following steps:

• selecting at least one inspection area (Z) of the container (2) so that for each inspection area (Z):
• a temperature of a wall of the container has a homogeneous value over a whole of said inspection area;
• a shape of the container and a surface condition of the container has homogeneous values over the whole of said inspection area;
• a spectral absorption of a material of the container has a homogeneous value over the whole of said inspection area;
• a spectral reflection of the material of the container has a homogenous value over the whole of said inspection area;
• formalizing a simplified function fz such that E(x, y)=fz(Ir(x, y), E(x, y) being the glass thickness at a point P and Ir(x, y) being the infrared radiation at the point P,
• measuring, for each inspection area (Z), an absolute glass thickness of the container according to the metric system in at least one measurement point (P) belonging to the inspection area (Z), by means of the contactless point-like thickness measurement system (11),
• measuring by means of the sensor sensitive to infrared radiation (6), the distribution of the infrared radiation Ir emitted by the container (2) at least in each inspection area (Z),
• determining, for each container and for each inspection area (Z), a relationship between the measurement of the thickness taken at the measurement point and relevant infrared radiation at said measurement point, said relationship being such that E(x, y)=fz(Ir(x, y)), fz being the simplified function, and E(x, y) the absolute glass thickness measured at the point P by the contactless point-like thickness measurement system (11) and Ir(x, y) being the infrared radiation measured at the point P,
• and from said relationship E(x, y)=fz(Ir(x, y)) and from the distribution of the relevant infrared radiation of each inspection area, determining the distribution of the glass thickness of the container of each inspection area (Z).