Eng. Mihael BOROS

Contributions to rationalization and optimization of mechanical wood processing on wide belt sanders

SCIENTIFIC COORDINATOR: Prof.Dr.Eng. Nicolae TARAN

PhDThesis asserted at the „Transilvania” University of Brasov – Faculty of Wood Industry, September 2006.

Sanding is one of the most important mechanical wood processing operations, being the one which determines decisively the quality of the final processed surface. Sanding has its peculiarities due to the fact that a great number of small chips is simultaneously detached, as a consequence of the interaction between many differently oriented “knives” (granules) and wood. The present PhD thesis pursued an in-depth study of this complex interaction, along with performing a synthesis of the existing information and adding new contributions by experimental research.

One of the main objectives of this thesis envisaged the creation of a database for the optimization of the wide belt sanding process, based on the analysis of new species, less or not at all studied previously. In order to achieve this goal, an ample bibliographical research was performed, as well as theoretical studies and experimental research regarding the parameters which influence the sanding process.

In order to complete it, a very detailed study regarding the roughness of processed poplar and fir surfaces was performed, by using a wide belt sander. The variable parameters taken into consideration were: the sanding speed (v), the feed speed (u), the sanding pressure (p), the cutting height (h) and the grit size of the sanding belt. The experimental results revealed as optimum sanding conditions the following: v=18m/s; u=10m/min; p=0,6bar; h=0,2-0,3mm.

Another main objective of the thesis was to perform a study of the assembly "pressure bar – abrasive belt - board", in order to point out the importance of the correct choice of the sanding pressure. By means of the ANSYS program based on FEM, the state of stresses within the contact area was analysed for different values of the pressure.

Based on the results obtained, an original computer program was elaborated, which allows to calculate the chosen parameter depending on the other parameters and on the optimization criteria. This program may be used as a starting point for the informatization of the sanding process, with a view to general optimization of wood processing technologies.