Development of continuous pressing method for producing LVL cylinder

点击翻译按钮获取中文摘要

An improved press-drying method of SUGI veneers which were used as raw materials for LVL cylinders in the present Research was proposed. The experimental results showed the new method was more effective than the conventional ones. An end-jointer for making finger-type joints of veneers was designed. The machine set up in trial worked well and the jointed parts made by this machine had strength comparable with that of non-jonted parts.A caterpillar-type continuous press with a radio ferquency heating function was used for pressing an endless molding LVL.The press had a pressing part 300 mm wide and 700 mm long. Molding jigs made of wood with electrodes were used one after the other to make a continuous mold pressing. The products are 1/6 parts of a LVL cylinder with 390 mm outer diameter and 30 mm thickness. The experimental results showed the feasibility of this method in the production rate of 1 m/min if the length of the pressing part was extended to 7 m.Six pieces of the molded LVLs were edge-jointed in tang-and-groove type joints with RF glue to make a hollow cylindrical post of 5, 400 mm length. Urethane resin foam with density of 0.38 g/cm^2 was filled inside the post. The filling was very effective to improve the lateral compressive strength by 40 times as that of a non-filled post. The stress distribution was calculated by the finite element method and used for the prediction of the failure criteria.Slender veneer tapes of lateral direction reinforced with craft papers were winded to a heated mandrill to manufacture an LVL with helical-winded veneers. This technique is commonly used for manufacturing paper tubes. The trial seemed successful and the application of the technique to LVL production will be promising.