木ねじ

The experimental study presented in this paper consists of two series of tests concerned with jointing performance of wood screws for particleboard. In the first series of test, withdrawal test of wood wcrews from the face or edge of particleboard were performed. In withdrawal tests, the sizes of wood screw and pilot hole were varied and the driving torque was also measured. In the second series of tests, two specimens (rail and post) of particleboard were constructed in the form of L-type with wood screws, Knife thread insert nuts or adhesive, and the rail was placed in the flat position. The bending load (out-of-plane force) was applied to it, and static and repetitive bending tests of L-type construction were carried out. And from the measured results, the angular stiffness of the L-type construction was calculated from Eq. (8'). The results obtained are as follows. (1) Under a constant diameter of wood screw, driving torque and withdrawal resistance increase with increase of the length of screw. However, under a constant length of wood screw, driving torque increases with increase of the diameter of screw, but withdrawal resistance decreases. These results indicate that it is more effective to use longer wood screws than to use thicker screws. (2) Withdrawal resistance of each size of wood screw is affected by the diameterratio of pilot hole to wood screw and it shows the largest value at the diameter ratio 0.5. Considering a labor efficency at the jointing work, however, it seems better to use the diameter ratio 0.6 to 0.7. (3) The bending fracture load of L-type constructinos connected with wood screws is affected considerably by the length of wood screw and is under control of the internal bond strength of particleboard. The angular stiffness of L-type construction depends on both withdrawal resistance and the resistanceto the deformation of the wood screw caused by bending load. The fracture load and the angular stiffness show larger values in the case that the L-type construction is connected with insert nuts than those in the case of wood screws. (4) The strength and the stiffness of L-type construction are improved by jointing with both wood screws and adhesive. Especially, by use of epoxy resin, the strength increases remarkably. (5) The fatigue strength of L-type construction connected with each type of joints is in proportion approximately to their static strength.