Characteristics Of Wood Dust During Milling Of Pinus Radiata And Red Oak

Wood is an important renewable resource in the world,people's life cannot do without wood.However,it is easy to produce a large amount of wood dust in the process of wood processing production,which greatly limits the development of wood processing industry.Therefore,it is urgent to study the characteristics of wood dust.The physical and chemical characteristics of wood dust are more complex.The density,moisture content,milling direction and milling parameters of solid wood materials all directly affect the dust production and particle size,which brings a lot of troubles to the wood industry.Reducing dust generation by controlling moisture content and milling parameters is one of the important research directions of dust removal at present.In this paper,we choose the common Pinus radiata and red oak as the research object.The water content,milling direction,spindle speed,feed speed and milling depth were selected as the main variables,using high-speed wood composite processing center equipment for wood milling test.At the same time,using laser dust instrument and particle size analyzer to explore the influence of various factors on the mass concentration of suspended wood dust and the particle size and distribution of settling wood dust.The main conclusions are as follows:(1)Concentration and particle size distribution of wood dust.The longer the distance from the center of the plate,the lower the mass concentration of suspended dust and the smaller the median particle size of settling dust.Near the plate,the dust mass concentration and median particle size are the highest.Therefore,most of the dust settles near the plate,and the dust collector is set near the plate to make the best dust removal efficiency.More fine dust wafts to the positive direction of the X axis.The geometric center of the dust cover can be slightly offset in this direction,or dust removal equipment can be added in this direction to effectively prevent the dust from escaping.(2)Mass concentration of suspended wood dust.The mass concentration of suspended dust in red oak is higher than that in Pinus radiata,and the mass concentration of suspended dust in transverse milling is lower than that in longitudinal milling.The concentration of suspended dust was positively correlated with spindle speed and milling depth(greater than1.49mm).It is negatively correlated with water content and feed speed.Orthogonal test shows that the main effect order of each milling parameter on dust mass concentration is as follows:feed speed > spindle speed > milling depth.Therefore,under the condition of ensuring the processing quality,the milling direction is transverse milling,and the selection of higher feed speed,lower spindle speed and milling depth can reduce the mass concentration of suspended dust.(3)Particle size distribution and particle shape characteristics of settling wood dust.For settling dust in the range of 0 ? 400 ?m,the median particle size of red oak dust is smaller than radiradipine dust.The median particle size of dust produced by longitudinal milling is smaller than that produced by transverse milling,and the parameters of dust length-width ratio,roundness,firmness and bluntness are greater than that produced by transverse milling.The median particle size,dust aspect ratio,roundness,firmness and dullness of settling dust were positively correlated with moisture content,feed speed and milling depth(greater than 1.49mm),and negatively correlated with spindle speed.Orthogonal tests show that the main effect sequence of milling parameters on the median particle size of dust in the milling process of Radiance Pine and Red Oak is as follows: feed speed > spindle speed > milling depth.The feed speed has the most significant effect on the median particle size,while the milling depth has the weakest effect.Therefore,combined with the single factor test results,the selection of transverse milling,higher feed speed and lower spindle speed can reduce the median particle size of dust.(4)Model of dust mass concentration and particle size.According to the orthogonal test results,the particle size distribution of Pinus radiata and red oak dust conforms to the Rosin-Rammler distribution.In this paper,the prediction model of dust mass concentration and median particle size established by linear regression method has a high correlation with the actual forecast data.