IML-Resi PD-400 drilling tools (IML System GmbH, Wiesloch, Germany) were used to study the influence of the feed rate and the rotational frequency of the drill bit on the drilling resistance (DR) measurements. The study presents theoretical aspects concerning chip formation, kinematics (speeds, cutting angles, chip thickness) and cutting forces distribution during the drilling process. Drill bit rotational frequency and feed rate have an impact on nominal chip thickness or a feed rate per major cutting edge of the drill bit, and were correlated to DR measurements. Varied rotational frequency and feed rate had a significant impact on DR and feeding resistance (FR). Positive correlations between feed rate per major cutting edge and DR (FR) for the individually tested wood species can be described by allometric functions (R 2 = 0.93-0.99). Wood density had a partial impact on correlations between feed rate per major cutting edge and DR (FR).
Due to the deterioration of the environmental situation, an increasing number of coniferous trees are affected by butt heart rot. For a more sustainable use of resources, one needs to use round assortments with the presence of sound rot for the manufacture of sawn products. I-beams are widely used in low-rise wooden housing construction. High installation speed without the use of heavy equipment and ease of assembly increase the speed and adaptability of building construction. A method for manufacturing I-beams from corner elements obtained as a result of cutting round timber with heart rot is proposed. The elements of the angular cross section are glued together to obtain an I-beam. The strength characteristics of an I-beam glued from angular cross-sectional elements are determined. It was established that the design characteristics of I-beams obtained by the proposed technology withstand operational loads. Values of normative and shear stresses arising upon application of loads do not exceed 50% of the permissible values. The beam deflection does not exceed 80% of the permissible deflection value. The use of round timber with core rot increases wood resources for low-rise housing.
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