Blow molding machine for container, in particular plastic bottle, manufacture has pressure gauge to determine pressure in container and detect leakage

摘要

A pressure gauge(11) monitors the pressure inside a container(2) to determine whether leakage exists. Pressure in the containers(2) may be determined after the blowing stage. Pressurized gas is fed to the container via an inlet valve(7) and the pressure gauge(11) is located downstream from the valve. A blowing nozzle(5) for container inflation makes a pressure-tight connection with the container and the pressure gauge may be positioned upstream and/or downstream and/or at the blowing nozzle. The pressure gauge is connected to an analysing unit which compares the measured pressure with a set threshold value. Faulty containers are removed from the production line. Container pressure may alternatively be measured during the blowing process after closing the inlet valve and before opening a pressure release valve(9). Pressure is recorded for 0.005-0.5, preferably 0.1-0.2, and more preferably 0.15 second.