EN
This study was carried out to determine the effects of pilot hole, screw diameter, and wood composite panel type on the diagonal compression and tension strength properties of particleboard surfaced with synthetic resin sheet (LamPb) and MDF surfaced with synthetic resin sheet (LamMDF). Two different diameter of screws (3,5 and 4 mm) and three types of pilot holes (either 70 or 85 % of the root diameter of the screws, and without pilot hole) were utilized for constructing the test specimens. Samples with pilot hole gave higher strength values than control samples of all T-type corner joints. Namely, the use of pilot holes of the proper diameter significantly increases the bending and tension strength of the screws in the material. Pilot hole diamater was found to have a larger influence on bending moment resistance than screw diameter and panel type. Results of means separations of moment resistances indicated that in general the joints loaded in bending have greater moment resistance than those loaded in tension. LamMDF corner joints were stronger than LamPb corner joints. As case furniture constructions are under bending forces, in LamPB using 3.5 x 50 screws with a pilot hole of 70 % of the root diameter of the screws, in LamMDF using 4 x 50 screws with 85 % of the root diameter of the screws can be recommended as the most robust corner joint type for case furniture. As case furniture constructions are under tension forces, in LamPB using 4 x 50 screws with a pilot hole of 85 % of the root diameter of the screws, in LamMDF using 3.5 x 50 screws with 85 % of the root diameter of the screws can be recommended.
PL
Wpływ wiercenia otworów na wytrzymałość na zginanie skręcanych połączeń półkrzyżowych w meblach. Celem pracy było określenie wpływu wiercenia otworów, średnicy śruby oraz rodzaju materiału płytowego na wytrzymałość na zginanie oraz rozciąganie połączenia. W badaniach uwzględniono płytę wiórową laminowaną oraz MDF laminowaną, 2 średnice wkrętów oraz 3 rodzaje otworów (o średnicach 70% i 85% średnicy wkrętu oraz bez uprzednio wykonanego otworu). Wykazano, że odpowiednia średnica otworu zwiększa wytrzymałość na zginanie i rozciąganie połączenia.