Comparative analysis of physical and mechanical characteristics of bent elements from different tree species
S.A. Grytsak, S.V. Gayda
Abstract
The technology of bending solid wood with preliminary hydrothermal treatment and with the use of production residues as well as consumed wood as raw materials has been developed. The analysis of the equipment for performance of technological operations of research process of reception of curvilinear preparations is carried out. A method was developed and the length of the defect-free arc of bent wood elements of different breeds and ages was investigated using laboratory installations for hydrothermal treatment and bending of samples. The regression equations for wood of ash, pine and oak species are obtained, which describe the process of wood bending and establish the dependence of the quality of wood bending on them individually and comprehensively. Nine groups of graphical dependences are constructed, which clearly describe the researched process. It is proved that the used wood of the oldest age is more susceptible to bending than freshly cut and dried wood and is suitable for this technological process. Calculations have shown that in our studies, the maximum length of a defect-free arc for ash wood is 40.95 mm, for pine – 37.45 mm, and for oak – 35.25 mm. It was found that wood samples are best bent with increasing duration of hydrothermal treatment and humidity of the studied samples and reducing their size. It is determined that the optimum humidity of the samples for the bending process is a humidity of 25-30%, because the greater the value of this factor leads to the pressure of free moisture on the walls of wood cells and the destruction of bent samples. Practical recommendations have been developed for the introduction of solid wood bending technology with prior hydrothermal treatment, which is economical in terms of wood raw materials and allows to obtain blanks of different complexity of shape.