- Highly efficient method for changing layer configurations
- Changeovers in piston position in a matter of seconds
- Special flushing channel design keeps flow from stagnating
Processing Technologies International (PTi), a leading manufacturer of sheet extrusion machinery, is in the final stages of formalizing a commercial agreement with a leading global tooling manufacturer for the exclusive sourcing of its patented layer-flipping technology. This technology allows processors to quickly change the position of extrudates from two extruders in a coextruded structure without tedious disassembly and costly shutdowns. The final announcement on commercialization will follow upon completion of a formal agreement.
Changeovers in piston position in a matter of seconds
Changeovers in piston position due to hydraulic actuation of the piston cylinder and special flow design are accomplished in a matter of seconds as opposed to conventional techniques which require some machine disassembly and could take up to several hours, according to the company.
Since being awarded with the original design patent in 2013, the company has continued to develop this technology and has filed a second design patent just over a month ago. U.S. patent 8,490,643 was granted to PTi on July 23, 2013. The diverter valve features a dual-piston valve which is moveable in a stationary body. The body has two entrances that feed from separate extruders. The first position of the valve allows the material to enter the piston valve and permits a straight through flow path. Normally, this would produce an A-B structure. When the alternated position two is selected, the materials are routed through crossover flow paths that changes extrudate positions. This produces a B-A structure.
Special flushing channel design keeps flow from stagnating
During position changes, a special flushing channel design keeps flow from stagnating for quick and efficient changeovers. The practical use for the diverter valve is its quick “real-time” purging of cap layers in a multilayer co-extrusion structure for sheet production, according to the company. The diverter valve enables the processor to purge the cap layer extruder back into the inner layer of the structure while an alternate cap layer extruder runs a specific resin formulation (i.e., different color). Each cap layer (both inner and outer layers) can utilize this special valve to permit this real-time purging for rapid changeovers. This occurs without shutting down the line, thus permitting recovery of the purged resin directly back into the structure instead of losing the material onto the production floor and recovery through a grinder.
The company will offer the layer-flip technology on new coextrusion systems and also as a retrofit to existing machines.