METHOD OF MANUFACTURING CONTAINERS

摘要

The process serves the purpose of producing containers. A heated pre-form made of a thermoplastic material is stretched and inflated with the aid of a gas under pressure for purposes of molding the container. The inflating process is divided into a preliminary blowing period with a gas under a lower level of pressure and into a subsequent primary blowing period with a gas under a higher pressure level. The ratio of the container diameter to the inner diameter is selected to be greater than 4.0. The pre-form has a median wall thickness of greater than 3 millimeters and at least at the beginning of the preliminary blowing phase is provided with a material temperature greater than 70 degrees Celsius. The pre-form at least at the beginning of the preliminary blowing phase in the area to be oriented is provided in the area of its upper surface with a temperature which is at a maximum equal to a medium temperature of the inner surface of the pre-form in the area to be oriented. The temporal duration of the preliminary blowing phase is selected to be less than 1.0 second. During the preliminary blowing phase the pre-form is expanded to at least 50 percent of the volume intended for the finished blown container.