| Wood surface roughness is an important indicator of the quality assessment of wood product surface.It has a significant impact on the surface friction and wear, sealing, the quality of painting,decoration and consumption of adhesives and coatings. The process design and the allowance of machining both depend on wood surface roughness.It is an important part of wood surface quality inspection. In recent years, researches about surface roughness focus on methods of how to measure the surface roughness of the wood and the causes of roughness. In terms of the causes of surface roughness, the cutting tool was rarely a key point, the study between cutting parameters and roughness is also relatively less, as well as combined with cutting tool materials.Different cutting parameters directly affect the quality of the wood cutting surface, and because of hardness and different chemical composition of cutting tool materials, different roughness after tool sharpening, different degree of affinity between cutting tool materials and processed materials, different friction coefficient between cutting tool surface and workpiece, different materials of cutting tool makes different surface roughness quality of workpieces.In this paper, the single factor test was conducted first to study the impact on wood surface roughness profile arithmetic square root Ra and micro roughness ten point height Rz when changing main parameters of milling processing,such as spindle speed, feed rate and the materials of tool. The results showed that three variables had a certain degree of influence on wood milling surface roughness.Overall, in a certain range, with the increase of spindle speed, the surface roughness Ra and Rz decreased.The feed speed was slower, the better surface quality effect. Different tool materials had direct effects on wood cutting surface roughness,and the relationship is not significantly linear.The second part was the single index orthogonal experiment.When using diamond, carbide, high-carbon steel as cutting tools, the effect of three main cutting parameters of spindle speed, feed rate and cutting thickness on the wood surface roughness Ra was studied respectively. Through the methods of range analysis and analysis of variance, the degrees of different impact factors on wood surface roughness were analyzed, and the optimum processing parameters were also determined. The results showed that the surface quality of carbide cutting Douglas fir and southern pine was better than that of the other two kinds of tools, which was relatively stable, the surface quality of high carbon steel cutting Xylosma was better than that of the other two types of cutting tool and the surface quality of diamond cutting Dalbergia latifolia was better than that of the other two kinds of tool. For the Dalbergia latifolia, using diamond as tools with a spindle speed of 11000r/min, a feed rate of 1000mm/min and a cutting thickness of 1mm, cutting was able to obtain the best surface quality. For the Xylosma, using high carbon steel as tools with a spindle speed of 11000r/min, a feed rate of 1000mm/min and a cutting thickness of 2mm, cutting was able to obtain the best surface quality. For the southern pine,using carbide as tools with a spindle speed of 9000r/min, a feed rate of 1000mm/min and a cutting thickness of 1mm, cutting was able to obtain the best surface quality. For the Douglas fir, using carbide as tools with a spindle speed of 11000r/min, a feed rate of 1000mm/min and a cutting thickness of 1mm, cutting was able to obtain the best surface quality. Finally, according to the test data of the surface roughness Rz, mathematical models were set up, based on conducting multiple linear regression analysis of the surface roughness after milling wood of four speicies. These models were able to more accurately predict the respective wood surface roughness of timber in different cutting conditions, providing theoretical support for the real production and related research. |
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