Measurement of the boxing travel by the stretching function, in an installation for producing containers

Method for parameterizing an installation for manufacturing containers by stretch blow molding from blanks made of plastic material, this installation comprising:

• a mold equipped with a wall defining a cavity bearing the impression of the container, extending along a main axis of the mold and with a mold bottom that can move axially in relation to the wall between an extended position and a retracted position,
• a device for controlling the movement of the mold bottom, able to exert an axial thrust on the mold bottom to move it from its extended position to its retracted position and vice versa;
• a stretching device comprising a stretching rod that can move axially in relation to the wall and an electric machine that is connected to the rod;
• this method comprising the operations consisting, from an initial configuration in which the rod is in a raised position away from the mold bottom and in which the mold bottom is in its extended position or in its retracted position, in:
• causing the electric machine to operate as a motor to exert on the rod an axial driving force that moves it toward the mold bottom;
• evaluating the result of the axial forces exerted on the rod;
• provided that a variation in the result of the forces is detected, assigning a position of origin to the rod;
• storing the position of origin;
• actuating the movement of the mold bottom toward its retracted position or, respectively, its extended position;
• assigning the corresponding, so-called final, position of the rod to the rod;
• calculating and storing the distance, called travel of the rod, between the final position and the position of origin.