The study on glue-applying methods and hot-pressing technology of parallel strand lumber

Parallel strand lumber (PSL) was manufactured from the veneer strand cut from the poplar broken veneers of the plywood enterprises, by analyzing the influence of the size of veneer strands, the glue concentration and glue-applying time on the glue-absorbing amount of veneer strands, the influence of three different glue-applying was, hot-pressing time and temperature on the physical and mechanical properties of PSL was reviewed and the hot-pressing technology was optimized. The experiment results showed that the size of the veneer strands have not notable influence on the gluing-absorbing amount, and mainly affect the homogeneity and appearance quality of the product. The glue concentration is one main factor to affect the glue-absorbing amount of veneer strands and PF resin of 30% concentration was chosen. The glue-applying way is the main factor to affect the mechanical property of PSL. The hot-pressing time and temperature have significant influence on physical and mechanical properties of PSL. Comprehensively considering, the physical and mechanical properties and homogeneity of products are better using the veneer strands with 100 mm length, the glue-spraying way and hot-pressing technology with the time 35 min and the temperature of 150°C.

Veneer warpage deformation measurement based on 3D laser scanning technology

In this paper, the warpage of the Taxodium hybrid ‘zhongshanshan’ veneer was measured by 3D laser scanning technology. The results showed that, the deformation of this veneer was mainly due to the warpage phenomenon along the cross striation of the wood. Air-drying shrinkage clearly enlarged the length in the direction of cross striation compared to the direction of parallel grain. The air-dried veneer would incline 7-12° along the direction of the parallel axis. When peeling the wood of the Taxodium hybrid ‘zhong shan shan’, the diameter decreased, and the warpage degree of veneer increased. The average veneer warpage degree of sapwood was 21.18%, the intermediate wood was 28.20%, and the heartwood near piths was 40.88%. High resolution 3D laser scanning technology accurately, intuitively, and rapidly obtained the deformation of the veneer.