単板ストランドによる成形フランジとMDFまたはパーティクルボードによるウェブから成る木質Iビーム(第5報) 水蒸気噴射プレスによる製造と性能

摘要

In this study, the optimization of the manufacturing conditions in veneer-strand-flanged I-beam production by steam-injection pressing and methods to further reduce the pressing time were investigated. The main results revealed that conventional hot pressing using diphenyl methane diisocyanate (MDI) resin between the strands as well as between the web and the flange produced I-beams within a pressing time of 8 min. This time was further reduced to 6 min by using steam-injection pressing. It was concluded that a primary steam injection duration of 10 s in the first stage of flange compression (75-mm platen distance), followed by a 5-s secondary steam injection duration while the press was closing was the optimal combination that yielded I-beams with balanced mechanical properties and dimensional stability. It was also observed that it was more appropriate to use a roll-press splitter for strand preparation instead of a saw-cutting method in the steam injection pressing technique.