Study On Mechanism Of Walnut Shell Cracking And Design Of Walnut Shell Cracking Machine

Walnuts are rich in fat, protein, vitamin E and other nutrients, which are beneficial to human health. The walnut planting area, yield and output of Shaanxi province are increased year by year, walnuts were deep processed to improve the added value of walnut. Shell and kernel taking is the first step in any form of walnut processing, and walnut shell cracking still get hit by artificial way in any places. A variety of walnut shell cracking machine was designed to solve this problem of walnut shell cracking. However, the rate of shell cracking and whole kernel rate of walnut shell cracking machine are not high because of the complex species and different sizes. A shell cracking equipment for walnut has been designed based on the research of the walnut shell cracking mechanism to solve this problem,and this subject is supported by the Education Department of Shaanxi Province(project number: 2013JK1041).Firstly, walnut shell cracking mechanism has been researched in this thesis. walnuts size, shell thickness, shell kernel space and other physical parameters of walnuts have been measured. The three-dimensional model of walnut has been established according to the physical parameters of walnut. shelling experiment of walnut in different directions have been conducted by the universal material test machine to find the desired shell cracking force and best shell cracking position. Then, the three-dimensional model of walnut has been introduced into the finite element analysis software Workbench, the finite element analysis have been carried on according to the shell cracking force obtained by extrusion test for the model of walnut. And the walnut’s stress and strain under stress have been drew. The best cracking walnut shell extrusion direction has been determined from the alignment static compression test and finite element analysis results.Secondly, the design principle of walnut shell cracking machine has been determined. Shell cracking machine has been designed with gap extrusion shell cracking method and directional beating method according to the results of walnut shell cracking mechanism and the current works of foreign mature walnut shell broken machinery. In the process of studying, because of each walnut size differences, shell cracking mechanism has been designed with regulating device according to the actual condition of walnut to adapt different sizes of walnut. Therefore, three-dimensional model of walnut shell cracking machine has been designed based on the broken shell program, and the three-dimensional model of walnut shells broken machine has been optimized according to the method of mechanical design theory and optimization theory. Finally, the sizes of the equipment has been determined and prototype were processed out.Thirdly, the final design has been determined by testing the prototype. The eccentric extrusion walnut shell cracking machine and hitting walnut shell cracking machine have different effects. Therefore, walnut shells have been broken with two different types of equipment by orthogonal test method and the design scheme of the thin skinned walnut shell cracking has been determined according to the shell cracking effect, processing cost, convenient operation, equipment life and environmental aspects.