The Study On Bending Processe Of Nan Bamboo Sheet With High Temperature And High Humidity

Phyllostachys pubescens sheets have an excellent bending capacity,so it’s a perfect option being used to bending members in furniture and interior decoration.This study used Phyllostachys pubescens sheets as the research object,and achieved a good effect both in bending degree and shape fixing through microwave heating and softening,manual bending and drying stereotypes.In this research the main influence factors of each stage were studied.Research show that:1) The microwave power, time and initial moisture content of specimens have a significant effect on bamboo specimens softening effects.With the increasing of microwave power, the softening effect is enhanced first and then weakened. When the microwave power is very low, intensity of molecular motion is not high enough, softening of bamboo is insufficient; When the microwave power is too high, the structure of bamboo will be destroyed to some degree,and losing of too much water also caused decrease of plasticity and poor softening effect. With the increasing of microwave treatment time, the softening effect is enhanced first and then weakened. When the microwave treatment time is too short, the specimen temperature is too low to meet the bamboo softening require temperature, so the softening performance is not ideal; but when the microwave treatment time is too long, It will cause the decreasing of bamboo mechanical property and increasing of water loss,resulting in reducing of softening effect.The impact of bamboo moisture content on the softening performance is that the higher moisture content is,the better softening effect will be.The results of softening processing optimization analysis of Phyllostachys pubescens sheet within the scope of experiment showed that the best process combination is initial moisture content as90%, microwave power as500W, microwave time as240s.And the EOM of the specimen after microwave processing reduced by nearly80%then the untreated ones. The fact shows that the softening effect is excellent.2) The thickness of the specimen, with bamboo joint or not, bending direction(pressure surface is the inner side of bamboo or the outer side) have impact on bamboo sheet bending effect. The thinner of the thickness is,the better the bending effect will be,and the minimum bend radius it can reach is smaller,so we can choose thinner bamboo sheet under the situation that the request of bending radius is high.Bamboo joint have a significant influence on bending effect for the reason that areas of bamboo joint is easier to breaking when bamboo is bending,so the specimen with bamboo joint can achieve a smaller bend radius then the specimen without bamboo joint.For the bending direction,when the outer side of bamboo is tensioned,the bending processing is easier than the situation that the innner side is done,and it can achieve a smaller bend radius.3) The drying temperature hasn’t a significant effect on bending shaping effect.The bending shape can be fixed perfectly under the drying treatment from50℃to90℃,and select the drying temperature of70℃as a better processing parameter considering the cost and efficiency.Taking into account, the final moisture content of specimens have a significant influence on the bending shaping effect, and they are positively related. The lower the final moisture content of specimen is, the higher the bending pieces of dimensional stability is, and rebound is smaller.When the final moisture content is lower then9%,it can get a better bending shaping effectAssembly time has a significant influence on the bending shaping effect, the best assembly time is5h within the range of experiment.The results of the research on softening and drying process of Phyllostachys pubescens sheet is that,the minimum bending radius is40mm when Specimen without bamboo knot,thickness is5mm and the tension face is the outer side of bamboo and the minimum bending radius is70mm when the tension face is the inner side of bamboo; the minimum bending radius is80mm when Specimen with bamboo knot,thickness is5mm and the tension face is the outer side of bamboo and the minimum bending radius is120mm when the tension face is the inner side of bambooProcessing as the results of the research on softening and drying process of Phyllostachys pubescens sheet,5mm-thickness bamboo specimen without bamboo knot can be bending as to40mm-radius when the outer side of bamboo is tensioned, and to70mm-radius when the inner side is tensioned;5mm-thickness bamboo specimen within bamboo knot can be bending as to80mm-radius when the outer side of bamboo is tensioned, and to120mm-radius when the inner side is tensioned.