Patent EA-000144-B1 (EA)
Title: Base geometry of reusable pet containers
Inventor: SEUL ANDREAS
IPC: B29C49/18
Filed: 1996-04-26
Abstract: 1. Method of shaping base geometry of PET container particularly from polyethyleneterephthalate using blow form characterized in that container base geometry is shaped in said blow form to obtain a truncated conical base with practically straight line forming, then said container is separated from said blow form and kept till said base obtains the shape essentially differ from a truncated cone. 2. Method according to Claim 1 characterized in that obtained after the first blow moulding stage the container base is additionally subjected to shaping in the second blow form, during which said base obtains the shape of two adjoining sections of the spherical surface, one of which has the radius r1, directed inside the container and another has radius r2 directed opposite the first one. 3. Method according to Claim 2 characterized in that in said second blow form r1 radius is bigger than r2 radius. 4. Method according to any of Claims 1-3 characterized in that in the first blow-moulding stage, a form is used in which forming side surface of truncated cone has an angle from 40 degree  to 70 degree  towards the container axis. 5. Method according to Claim 4 characterized in that said forming side surface of truncated cone has an angle of 60 degree  towards the container axis. 6. Method according to any of Claims 1-5 characterized in that base form is made of metal. 7. Method according to any of Claims 2-6 characterized in that the central zone of the container base obtains the bulged shape in the process of shrinking. 8. Method according to any of Claims 1-6 characterized in that the central zone of the container base has a flat surface and a support ring is arranged on the lower side of side surface. 9. Method of production reusable PET containers made of plastic particularly from polyethyleneterephthalate using blow moulding comprising base support ring characterized in that first blow moulding stage is performed on inwardly directed truncated cone and thus formed container with base having the shape of truncated cone take out from said blow form or keep in it and subject to shrinking till corrugation is formed in cross-section of the container base, bending point of which axially arranged above the base support ring and till internal stresses are relieved. 10. Device for production reusable PET containers made of plastic particularly from polyethyleneterephthalate comprising first and second blow forms, arrangement device to open the first blow form, heating device to heat plastic product to the required high temperature, pressure device to shape and to achieve base geometry a truncated conical base insert on which, in the first blow-moulding stage, the pre-form of a base geometry of the container in intermediate product form is shaped, having a cross-section with a corrugation characterized in that the first blow form has a base shaped as truncated cone while the second blow form has an essentially slight upper convexity in the base. 11. Device according to Claim 10 characterized in that bases of blow forms are made of metal.