Method for manufacturing a container from a blank, including feedback in accordance with an actual pressure at the end of the pre-blowing step

Abstract

The invention relates to a method for manufacturing a container (), by drawing and blowing in a mould (), from a blank () made of plastic material, which includes the following operations: inserting the blank () in the mould (); controlling the opening of a pre-blowing solenoid valve () at a predetermined pre-blowing rate (D); measuring the current pressure (P) inside the blank (); detecting an actual time (t) for starting the pre-blowing step; calculating a time (t) for ending the pre-blowing step such that: t=t+Δt−δ, wherein: Δt is a predetermined time for opening the pre-blowing solenoid valve and δ is a predetermined constant; deducing therefrom an actual pressure (P) at the end of the pre-blowing step; comparing said pressure to a theoretical pressure (P); and if said pressures are found to be non-identical, ordering a modification of the pre-blowing rate (D).