Theoretical And Experimental Study On Using Conical Mold To Crack Bamboo Culm Into Fibers

Bamboo fiber processing technology has developed over the years,The production pattern of long bamboo fiber(bundle)mainly composed of cooking hammering or rolling crack fiber method and chemical mechanical method has been formed.These production methods have their own characteristics.However,the fiber separation method is backward,and the separation method is difficult to solve the problem of fiber slimming control..These problems make the production efficiency low,the quality of the produced fiber is unstable,the energy consumption is large,and the environmental pollution problem is more prominent.In 2014,Yao Wenbin et al.proposed a bamboo culm valgus cracking method.The method is based on the thermal viscoelasticity and structural characteristics of the bamboo culm.The designed outward turning device allows the bamboo culm to directly soften and reverse the deformation without cutting the piece to realize the delamination separation of the bamboo layer and directly crack and form the fiber.Since the production process is non-polluting,the original bamboo culm can be directly used as a processing material.It avoids the loss of utilization caused by cutting and processing bamboo,and its fiber production rate is high.The obtained bamboo fiber(bundle)has outstanding characteristics such as good elasticity,good toughness,good fiber fineness and uniformity.Based on the above-mentioned fiber-cracking method,this paper developed a bamboo culm crack-conical mold and a fiber-cracking test machine.Based on the characteristics of the biological structure of the round bamboo culm and the difference in the distribution of the bamboo vascular bundle in the radial direction.The softened bamboo culm is directly separated from the natural bamboo fiber with uniform thickness under the synergistic action of the axial compression load and the conical mold.The paper studies the mechanical model of the cracking of the bamboo cone mold by the experimental research on the cracking of the bamboo culm cone mold.The conditions for the cracking of the bamboo culm cone mold were obtained,and the optimum softening process and its fiber cracking parameters were determined,revealing the law of the bamboo culm cone mold fiber formation.The main research contents and achievements are as follows:A.the mechanical analysis model of the compression and deformation of the bamboo culm cone mold was established by using the film theory of the rotating shell.The cracking conditions of the cracking of the bamboo culm were obtained.B.According to the test of various parameters proposed in the cracking model of the fresh bamboo culm,the results showed that: The circumferential stress,compressive stress and yield limit proposed in the crack fiber model are closely related to the bamboo age,location,bamboo joint and water content of the bamboo.The experiment found that whether it is 1 year old,3 years old or 5 years old bamboo culm can not reach the plastic condition of the cracking of the bamboo culm cone mold.C.In order to reduce the elastic modulus and yield limit of the bamboo culm,the plastic condition of the opening of the bamboo culm cone mold is achieved.,the author conducted a softening test.Experiments show that the optimum softening process conditions are 8% softening liquid and 90 minutes softening time.The elastic modulus of the bamboo material after the softening process was reduced by 98.6% compared with that before the treatment.The bamboo culm treated by the softening process satisfies the cracking condition of the cracking model of the bamboo culm cone mold.1 year old radius of 42.64-50.36 mm,wall thickness between 6.88-8.98 mm,After softening environment treatment with a softening liquid concentration of 8% and a softening time of 90 minutes,the fiber can be opened when the fiber opening load reaches 20.37-28.02 KN.D.The optimum opening process of the bamboo culm cone die compression method is as follows: loading load 25 KN,cracking rate 1mm/min,mold cone angle 160°.Under the fiber opening process,the one-year-old bamboo material with a radius of 42.64-50.36 mm and a wall thickness of 6.88-8.98 mm has the best fiber cracking effect after being treated with a softening liquid concentration of 8% and a softening time of 90 minutes.Under the condition of the process,the bamboo culm cone mold compression and cracking method can separate the bamboo fibrils without destroying the fiber,and has better fiber cracking effect.Under this condition,the average length of extracted bamboo fibrils is 84 mm,the yield of bamboo fibrils is 30.50%,and the distribution of bamboo fibril fineness is relatively uniform.