Лесотехнически Университет

Резюме

The proposed study presents an investigation of the influence of the wearing and the belt drive parameters’ changes over the forced torsional vibrations in the saw unit of a wood shaper. These changes affect the elastic and damping coefficients of the machines’ elements. The research is done on the base of a concrete mechanic-mathematical model for numerical investigations of the torsional vibrations of a wood shaper’s saw developed by the authors. The main features in the construction of the wood shapers are rendered an account in this model. Work’s conditions in the practice are modeled with the variable moments on the drive electric motor and the wood shaper’s saw. The conclusions based on the numerical investigations are confirmed by the real conditions.

The results of the whole investigation are applicable to the direct well-founded recommendations concerning the operation of these machines. These recommendations are important for the increase of the accuracy and quality wood shapers’ production. At the same time the results of this research are useful for technical diagnostics of the wood shapers.

Резюме

Experimental studies during milling of solid wood were carried out. The current study was performed at the Laboratory of Woodworking Machinery, University of Forestry, Sofia. The measurements were carried out using universal milling machine FD – 3 (ZDM – Plovdiv). The correlations between fundamental factors influencing the milling process and target functions, such as cutting force and power, specific cutting work, specific power consumption have been investigated. On the basis of the analysis of the obtained results, practical recommendations have been proposed.

Резюме

The proposed study deals with the modeling of the free spatial vibrations of a woodworking shaper and its spindle. An original mechanical - mathematical model of woodworking shaper and its spindle, developed by the authors, is presented in this work. The model provides the opportunity to explore the free undamped space vibrations of this type of machinery. In this model the woodworking shaper and its spindle are regarded as rigid bodies, which are connected by elastic elements with each other and with the motionless floor. A system of matrix differential equations is compiled and analytical solutions are presented. The natural frequencies and mode shapes for a specific machine can be obtained with their help. The model is supplemented in order to investigate the free damped space vibrations of the considerate system. The new model takes into account the damping properties of machine's elements. A new system of matrix differential equations is developed and the relevant analytical solutions are presented. They allow various numerical solutions for specific machines. The models take into account the characteristics in the construction of woodworking shapers. They include all necessary geometric parameters of this system. Numerical solutions and graphs can be obtained with the help of the developed models. These solutions and graphs are necessary for analyzing the free undamped and the free damped space vibrations of a particular considerate machine.

Резюме

This study presents the results of conducted investigations of the forced spatial vibrations of a wood shaper, caused by the wear of the cutting tool. The paper is based on a specific mechanical – mathematical model, developed by the authors, which allows studying of vibrations of this type of machinery. In this model the wood shaper is regarded as a system of three rigid bodies, which are connected by elastic and damping elements with each other and with the motionless floor. This study renders an account the mass, inertia, elastic and damping properties and geometric parameters of the machine. A necessary system of matrix differential equations is compiled and analytical solutions are presented. The results of the numerical investigations are presented. They are obtained through modern software and by using parameters of a particular machine. The results show that the amplitudes of the body’s vibrations are relatively small but the amplitudes of the spindle’s vibrations are significant especially at resonance zones.

Резюме

Studies on the durability of tungsten carbide (TC) grooving and rebate cutter head and assessment of the quality of its sharpening have been conducted. The linear wear of the blade and the blunting radius when processing of massive coniferous wood and chipboard were studied. Recommendations were made regarding the preliminary preparation of the cutter heads and their effective operation.