The Structure Optimization And Test Of The Cellar Making Machine Based On Ergonomics

Flue-cured tobacco production plays a very important role in our national economy.Tobacco transplanting is one of the key processes in the production of flue-cured tobacco.In recent years,the well cellar transplanting technology has been rapidly developed and vigorously promoted because of its good thermal and moisturizing properties,promote the early growth of tobacco seedlings and other characteristics,the production and quality of the well cellar hole in this technology is one of the key factors affecting the growth of tobacco seedlings.Currently,most of the well cellars making machines are portable well cellar making machines that use small gasoline engines as power sources.Compared with manual drilling by tobacco farmers,the use of this machine can improve the efficiency of transplanting tobacco seedlings and reduce manual labor intensity to a certain extent,but the machine has high vibration,poor operating comfort,and unstable quality of well cellar forming during long operation.In order to solve the above problems,this study started from the vibration test analysis of the well cellar making machine,used ergonomic theory and analysis platform,and optimized the design of key components of the portable well cellar making machine,and finally verified by field tests.The main elements of the research in this paper are as follows:First,the DH5925 dynamic signal acquisition and analysis system is used to collect vibration signals from three key test points of portable,hand-held and cross-body type well cellar maker,analyze its time domain and frequency domain characteristics,and combine with the vibration evaluation basis in ergonomics,the hand-held well cellar maker is selected to be the most suitable;vibration testing and analysis of the four key test points when the selected model is working with different types of drill bits,and according to the vibration frequency,get the source of vibration at the key points.At the same time,according to the root mean square value(RMS)of vibration acceleration and the agronomic requirements of well cellar transplanting,a new type of tile and spiral blade combination drill bit structure was proposed;finally,the vibration at the handle of the hand-held well cellar maker and its transmission laws along the arm were studied,and improvement measures were proposed for the lever structure,handle structure and material.Secondly,a biomechanical analysis of the operator's upper limb arm system and back spine was carried out using ergonomic theory;Jack,ergonomic simulation analysis software,was used to simulate the operator's operation of a hand-held well cellar maker,and scored the lower back stress,working posture and fast upper limb movements of three different percentile figures.It shows that the existing well cellar maker has poor operational adaptability,and improvements to the variable length joystick are proposed.In combination with vibration testing and analysis,the joystick,gripping handle,backrest structure and materials were optimized.Then use the Jack analysis platform to perform before and after the optimization of comparative simulation analysis,the results showed that the lower back stress was reduced after the optimization,the working posture evaluation grade was reduced from grade 3 to grade 2,the total score of the fast upper limb was reduced from 5 to 4 and the comfort was improved.Then,finite element analysis software was used to conduct modal analysis on the optimized operating structure and the backpack device,and the results showed that its inherent frequency is far from the excitation frequency and does not resonate;at the same time,finite element static analysis was conducted on the backpack device,and the maximum stress value is much smaller than the permissible material stress,and the structural design meets the strength requirements.Finally,field trials of model machine were conducted.The vibration test analysis of the field operation of the prototype showed that the root mean square value of the vibration acceleration of the key test points was significantly reduced after the optimization;the field operation of the prototype was evaluated using the evaluation system of three first-level indicators of vibration damping,comfort and human-machine interface,and the results showed that the overall score of the optimized well cellar maker was good,which achieved the purpose of optimization.