PETpla.net Insider 05 / 2018

BOTTLE MAKING 34 PET planet Insider Vol. 19 No. 05/18 www.petpla.net Figure 4.10 Layout of the various trans- fer functions of a Blomax Series III blow moulding machine. Diagram courtesy of SIG Corpoplast. This machine keeps the preforms on the mandrels throughout the oven and blow section, turning bottles right side up after blowing. In this way the diagram differs from machines that handle preforms in other ways. Preforms enter the machine at the loading station. Fed by gravity, worm drives, star wheels or scrolls, pre- forms are turned about 180 degrees when they go through the ovens neck down. Next they are pushed onto the mandrels, which is accomplished by either holding them in nests and moving the mandrels up from under- neath or holding the mandrels and pushing the preforms into place. All machines have devices ensur- ing the preforms are rmly seated on the mandrels. Preforms that are not located rmly are removed from the machine by various means (g. 4.11). Figure 4.11 Preforms not properly seated on the mandrels are blown into an ejection pipe. Photo courtesy of SIG Corpoplast. The loading/unloading wheel turns clockwise as do the heating and blow wheels. The intermediate or transfer wheels turn counterclockwise. Loading of preforms onto mandrels and trans- ferring blown bottles from transfer III to the turning wheel are both accom- plished by this rst wheel. This dual functionality, that is found throughout rotary blow moulding machines, is pos- sible because the neck support rings, that are already fully nished in the preforms, are used to hold both pre- forms and bottles (g. 4.12). Figure 4.12 The loading/unloading wheel is the heart of the various pre- form and bottle transfers. Diagram cour- tesy of SIG Corpoplast. Transfer I takes mandrels with pre- forms to the heating chain from where they travel through the oven section. Transfer II then moves them from the heating chain to the blow wheel (g. 4.13). Figure 4.13 Transfer wheels transfer preforms and bottles from one machine function to the other. Diagram courtesy of SIG Corpoplast. The elongated shape of the trans- fer arms or grippers is due to the fact that they must take the preforms to and from the centre of the blow clamp, clearing the mould halves. Transfer III nally takes the blown bottles from the blow clamps to the loading/unloading wheel. Because they are still upside down on this machine, they are then transferred one more time into the bottle turning wheel before they exit the machine. Linear machines These machines often have devices that turn a number of pre- forms and bottles through 180 degrees. This number is governed by the number of cavities that the machine blows (g. 4.14). Figure 4.14 The cylinder on the left centres and holds the mandrels while the preform turning device places two preforms. Photo courtesy of Amsler Equipment. Most machines use individual mandrels, combining them in front of the blow clamp and shuttling them in with a hydraulic cylinder. Mandrels may wear where they have hardened locating rings that t into cut-outs in the blow mould halves. Please order your copy at the PETplanet Insider book shop: www.petpla.net/book3 Stretch Blow Molding Third Edition by Ottmar Brandau € 130,00 374 pages © Copyright Elsevier 2017, 2012