| The sanding force and normal force of wood and medium density fiberboard are basic indicators of the sanding performance of wood. They are produced by elastic and the plastic deformation of sanding section of wood, which are caused by the phenomenon of scrape, plough and cutting during the sanding medium having the relative motion on the wood. The sanding force and normal force of wood sanding are important parameters for designing and use of the sanding machine. The sanding force is important data to determine the power consumption of sanding equipment, input power of electromotor and the feeding force. The normal force is an important factor influencing the surface quality of wood and the friction between wood piece and pedrail, and they are also basic datum to choose the optimal conditions for sanding wood. Wood physical properties and sanding parameters are taken as the variables to investigate the sanding force and normal force change during wood sanding in order to get relevant mathematical models in this research. The purpose of this study is to reduce the power consumption of wood sanding so as to improve the work efficiency and the product quality, and to provide a scientific design parameter.In order to analyze wood sanding performance, several technological methods, such as signal gathering, signal analysis, orthogonal test, ANVOA and mathematic regression are introduced. The results are follows:In the orthogonal test, factors including the granularity of sanding (A), feed speed (B), sanding thickness (C), grain direction of wood (D), their effect on the test results are studied. The results show that the factor of sanding thickness is the most remarkable for Manchurian Ash(F.mandshurica Rupr.) and Mongolian Pine(P.sylvestris var. mongolica Litvin.), and it also presents positive correlation with sanding force and normal force. Considering the factor of the granularity of sanding, the normal force is more influential than that of sanding force. The values of sanding force and normal force of sample species,whose grain parallel to the direction of feed speed, are the biggest, and the following are 45°grain direction's and vertical grain direction's. The interactional influences between factors show regular change, [feed speed B×sanding thickness C]>[feed speed B×grain direction D]> [belt size A×sanding thickness C], [belt size A×grain direction D] exerts little influence.By studying influences of different grain directions and wood pieces, the results show that the influences of wood grain are remarkable. Sanding force is bigger than others during parallel direction sanding. The normal force is the smallest during vertical grain direction sanding. The diagram of real-time curves of the Manchurian Ash is similar to that of Mongolian Pine. It shows that the time gaps between the two big peaks approximately are 2.5×10-2 s.The diagrams of real-time curves of MDF and wood are quite different. It shows that the corresponding relationships are not obvious between the waves of sanding force and normal force.Sanding thickness is the most remarkable factor to influence the sanding forces. With the increase of the sanding thickness, the rise range of sanding force is bigger than that of the normal force. Corresponding relationships between sanding thickness with sanding force and normal force assume linear variation, regardless of sample species and data types.The factor of feed speed presents different change tendency when sanding the Manchurian Ash and MDF. The characteristics of real-time curves of the Manchurian Ash demonstrates two small wave peaks between two big wave peaks, and with feed speed adding, the two small wave peaks graph are becoming more obvious. When the feed speed achieves the selected maximum value, the curves of force tend to smooth-out. It can be seen from the diagrams of the real-time curves of MDF that the peak values change in a large range, and it presents an obvious rule that the big and small wave peaks appear alternately with no stable frequency.
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