| Walnut shell breaking is an important process in walnut processing.With the reduction of rural labor force,the low efficiency of walnut shell breaking has become a prominent problem restricting the development of walnut industry.In order to realize the mechanization of walnut shell breaking and solve the problems of large number of screening and grading and high rate of broken kernel in the existing walnut mechanical shell breaking methods,based on the contour characteristics and mechanical characteristics of walnut,a directional shell breaking method using vibration position adjustment is proposed and related research is carried out.Firstly,the physical and mechanical properties of walnut were tested.Then,based on the test results of walnut related parameters,a directional extrusion shell breaking scheme is designed,and the extrusion shell breaking process is analyzed theoretically.Finally,a walnut directional extrusion shell breaking test-bed was built,and the related process parameters of walnut directional shell breaking were studied.The main research contents are as follows:(1)Experimental study on physical and mechanical properties of walnut.Taking Yunnan 103 walnut as the test sample,the geometric parameters of walnut shape,100 grain weight,shell kernel gap and moisture content were measured;The breaking force and displacement of walnut shell were measured by universal testing machine.The results showed that after being disturbed by the outside world,walnut was easy to stand still on the horizontal plane with the middle suture facing upward,and applied force to Walnut along the transverse diameter direction of walnut,its shell breaking force and kernel crushing rate were lower than those in other directions,and walnut had the basis of directional shell breaking.(2)Walnut directional extrusion shell breaking scheme and test-bed design.In view of the problems existing in the existing walnut shell breaking machinery,the shell breaking law of walnut is summarized,a directional extrusion shell breaking scheme is designed,the extrusion shell breaking process is theoretically analyzed,and the key factors affecting the shell breaking effect are obtained.According to the shell breaking scheme,the overall design and component selection of the directional extrusion shell breaking test-bed are completed.(3)Study on the technological parameters of walnut vibration position adjustment.The walnut position adjustment scheme is determined.Based on the measurement of various physical parameters between the walnut and the vibration groove material,the vibration position adjustment process of the walnut is simulated and analyzed by using edem software,and the influence law of the vibration frequency and the inclination angle of the vibration groove on the walnut position adjustment is obtained.Based on the directional extrusion shell breaking test-bed,the single factor vibration attitude adjustment test is carried out,and the test results are close to the simulation results.The test results show that when the vibration frequency of the linear vibrator is 125 Hz and the inclination angle of the vibration groove is 5 °,the effect of vibration attitude adjustment is the best.(4)Study on technological parameters of directional shell breaking of walnut.Taking walnut shell breaking rate and kernel crushing rate as evaluation criteria,the selection range of belt speed,spring stiffness coefficient and pressing plate inclination angle was determined by single factor test method;Taking the belt speed,spring stiffness coefficient and pressing plate inclination angle as variables,the orthogonal test is carried out,and the above parameters are optimized and analyzed by using design expert 11 software,and the optimal parameter combination is obtained.Based on the walnut directional shell breaking platform developed in this paper,the directional shell breaking test is carried out.The results show that when the belt speed is 93mm/s,the spring stiffness coefficient is 42N/mm,and the pressing plate inclination angle is 2.5 °,the shell breaking rate is 97.2%,the high grade kernel rate is86.5%,and the broken kernel rate is 13.5%. |
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