| China is a big country of banana cultivation,and banana industry occupies an important position in China’s agricultural economy.Banana stalk is a by-product of banana fruit after harvest.At present,the by-product of banana stalk fails to attract enough attention and is usually discarded at will.Due to the long natural degradation period of banana stalk,it not only pollutes the environment,affects the re-planting and renewal of banana garden,but also brings diseases and pests,and endangers the ecological environment health.Banana stalk is rich in high quality plant fiber,suitable for making suits,shirts,ties and so on.Therefore,the extraction of fiber from banana stalk is beneficial to alleviate the shortage of hemp resources in China and improve the utilization rate of resources.The existing banana stalk fiber extraction equipment has low operating efficiency,high fiber fracture rate and easy to block the machine,which greatly increases the difficulty of extracting banana stalk fiber,in order to improve the working efficiency of the fiber extraction machine.In view of the above problems,this paper optimizes the scraping drum,scraping tool and output device of the drum scraping banana stalk fiber extractor,and tests the extraction rate and miscellaneous rate of banana stalk fiber as test indexes.It mainly includes the following contents:(1)Through consulting the literature,we could understand the structure characteristics and fiber function of banana stalk,and analyze the research status and prospect of banana stalk fiber extraction machine.(2)The moisture content,shear stress,transverse compressive strength and friction coefficient of metal materials were determined by experiments.(3)The structure and working principle of the drum scraping banana stalk fiber extraction machine were described.Through the analysis of the machine structure and working process,the main shortcomings of the current machine and equipment were summarized,and the improvement scheme was put forward.(4)According to the analysis of the problems existing in the machine operation,the key parts of the drum scraping banana stalk fiber extraction machine were optimized.Through the movement and force analysis of the scraping drum,combined with the whole machine structure,the size structure of the scraping drum was determined.In view of the situation that the flat blade scraper had great striking force on the fiber and was easy to cause fiber fracture,the cutting tool was optimized.The traditional flat blade metal scraper was replaced with the curved bionic scraper,so that when the scraper contacts with the fiber,the striking force was solved in the rotation--plane.At the same time,according to the bionic non-smooth principle,the convex hull structure was set on the curved surface to mimic the dung beetle head,so as to reduce the friction between the scraper and the stalk,so as to avoid the impurities from sticking to the scraper surface and affecting the operation effect and efficiency.In view of the output roller could not timely and accurately pick up the fiber problem,to improve the output roller shape structure with increasing the staggered thread structure on the surface of the output roller,increase the friction between the output roller and the banana stalk fiber,improve the stability of the output roller clamping fiber,and analyze the influence of scraping drum rotation on the surrounding air flow,in order to establish a mathematical model,analysis of the best installation position of the output roller.(5)The simulation analysis of scraping drum and scraper was carried out.Through the simulation analysis of scraping drum inlet motion,the whole machine of scraping drum was stable;Through modal simulation,established the scraping drum vibration frequency and mode number and the relationship between frequency and cumulative effective participation coefficient,the results showed that before the second order mode number,the frequency changed with the increase of mode number significantly,after the second order mode number,the frequency change was gentle,after the second order mode number,mode number increase had a greater impact on the frequency.Before the frequency was 1114 Hz,the cumulative effective mass participation coefficient increased in x and y directions and remained basically unchanged after 1114 Hz.Tired in Z direction product effective mass participation coefficient was basically not affected by frequency.Through the static stress analysis of the bionic scraper,the results showed that the stress and strain of the scraper mainly occur at the corner of the L-shaped cutter,and the maximum displacement occured at the blade,and the maximum displacement was 0.0152 mm.(6)Through single factor test,the influence of speed of scraper roller,number of scraper and feed amount of stalk on the extraction rate and miscellaneous rate of banana stalk fiber was studied,and the influence rules and excellent horizontal range of each factor on the test index were analyzed.The number of scrapers and the amount of stem feed were the influencing factors.Three factors and three levels orthogonal experiments were designed according to the response surface Box-Behnken,and the significance order and optimal level combination of each factor were obtained by means of variance analysis and response surface analysis,and the optimal parameters were predicted by Design-Expert 8.0.6 software RSM.The test results showed that the best results were obtained when the speed of scraping drum was 1 800 r/min,the number of bionic blades was 18,and the feeding amount of stalk was 8 pieces per time.The fiber extraction rate was 95.62 % and the heterogenicity of fiber was 18.72 %.Finally,the experimental results showed that the fiber extraction rate was 95.37 %,the fiber miscellaneous rate was 15.46 %,the main performance index could meet the requirements of agricultural machinery technology. |
PDF Full Text Request