Design and pilot production of a “spiral-winder” for the manufacture of cylindrical laminated veneer lumber

A new spiral-winder was developed for continuous manufacturing of cylindrical laminated veneer lumber (LVL), and a suitable resin adhesive for this cylindrical LVL manufacturing system was investigated. This phase was followed by trial manufacturing and evaluation of cylindrical LVL with the optimum resin adhesive identified. The results are summarized as follows. (1) The shortest gelation time was recorded with a mixture of two commercial resorcinol based resins (DF-1000 and D-33) at a weight ratio of 25∶75. (2) Bath temperature had a remarkable effect on the gelation time of the adhesive mix. (3) High bonding strength was recorded by 25∶75 DF-1000/D-33 adhesive mix at a high press temperature despite a short pressing duration. Based on the results of items (1) to (3), 25∶75 DF-1000/ D-33 is recommended for use in the new spiral-winder. (4) The mechanical properties of cylindrical LVL could be improved by using 25∶75 DF-1000/D-33 with wider veneer width and longer pressing time. (5) The mechanical properties, especially the modulus of rupture, of the cylindrical LVL manufactured require further improvement for practical structural application.