Calculation models of pressure and position of curved laminated veneer lumber in molds during pressing

Curved laminated veneer lumber (LVL) for use in furniture-making was produced from glue-coated pieces of rotary-cut veneers that were assembled and pressed between molds. Pressure was applied until glue-lines were set and finally held in an assembly of the desired curvature. Pressure was an important factor during pressing of curved LVL. In this study we deduced some equations for designing the shape of molds and calculating the total pressure from the mechanics. The results are summarized as follows: (1) The position angle of every section of curved LVL assembly in molds on the horizontal and the total pressure during pressing can be calculated in relation to the shapes and dimensions of the curved LVL. (2) The pressure distributions in the glue-line measured using pressure-sensitive film were in good agreement with the glue-line unit pressure provided for the experiment and calculation. Therefore, the equations deduced in this study were suitable for calculating the position angle and pressure of curved LVL in molds. (3) The total pressure on curved LVL was greater than the pressure on straight LVL. The total pressure consisted of the pressure on the glue-lines of straight LVL with the same length and width as curved LVL plus the supplementary pressure needed to bend the veneers. (4) The total pressures and position angles of curved LVL in molds were affected by the shape, bent angle, and length of each section of curved LVL.The outline of this study was presented at the 48th annual meeting of the Japan Wood Research Society, Shizuoka, April 3, 1998