Patent ID: 8052904

Claim:
Process for forming containers from blanks comprising preforms made from thermoplastic material, the containers being formed using a stretch-blow moulding machine of a rotary type comprising at least one blow-moulding mould, mounted on a periphery of a carousel rotated continuously about an axis, the blow-moulding mould operating in a cyclic manner according to a forming cycle, the process comprising: a step of placing a preheated blank in the blow-moulding mould having, in a closed position, a mould cavity forming a cavity of the container to be blow-moulded, a step of closing the blow-moulding mould, a step of blow-moulding the blank in the blow-moulding mould with a blow-moulding nozzle and, approximately simultaneously, a step of stretching the blank by inserting an elongation rod inside the blank, and pushing against a base of the blank to facilitate an axial stretching of the blank, a step of flushing an inside of the container by injecting air for a flushing time Tb, a step of raising the elongation rod, a step of grasping the blown container by an external grip, a step of opening the blow-moulding mould, and a step of setting, at each production start-up of the stretch-blow moulding machine, a compensation period during which a duration of the flushing time Tb is automatically varied, temporarily, during a predetermined time at each start-up of the production of the containers, for first several carousel rotations until a temperature of the blow-moulding mould is stabilized, after which the flushing time Tb becomes constant, thereby establishing thermal conditions in said containers at which the containers are formed during the first several carousel rotations at the production start-up at the temperature of the blow-moulding mould that gives the containers a final volume corresponding to the final volume of the containers formed during the steady-state operation of said stretch-blow moulding machine, during the period of production when the temperature of the blow-moulding mould is stabilized.