Determination of the influence of pressing parameters on the bending process of beech furniture blankets

Abstract

It is substantiated that the technology of cold bending of pre-pressed blanks has a perspective. It was established that the minimum bending radius depends on the direction of pressing and the degree of pressing. It was determined that pressing in the radial and tangential directions does not give the desired effect during bending, which is evidenced by a large number of defects (respectively 47-67% and 34-61%) associated with the specific structure of the wood. In particular, during pressing, the wood cells are deformed along the pressing line, and during subsequent bending, the elongation of the wood in the peripheral part passes across the pressing line and is only partially compensated by the pressed cell walls. It was experimentally established that the results are significantly different when the workpieces are axially pressed. When the degree of pressing is increased from 15 to 25%, the number of high-quality blanks increases and amounts to 83-97%, respectively. This can be explained by the fact that during axial pressing, wood cells are deformed along the line of pressing. During subsequent bending, the elongation of the wood in the peripheral part also takes place along the line of pressing and is compensated to a much greater extent by the pressed cell walls. It was found that when the workpieces are pressed along the axis, uneven pressing along the length occurs, that is, only approximately half of the length of the workpiece is pressed. This is probably the main reason for the defect. Additional research and possibly new technological solutions are needed to solve the problem of uneven pressing during axial pressing. Prospective directions of research into bending processes of beech furniture blanks have been formed, in particular from the development of new bending technologies; optimization of pressing parameters; modeling of bending processes; study of the influence of humidity and temperature; study of the strength and durability of bent blanks.