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Report of Pecan Shell Break and Shell Kernel Separation Production Line(4)

Dec 09, 2019



1) Labor-saving, time-saving, high productivity This production line is suitable for large-scale batch processing of walnuts. Taking small production lines as an example, the productivity has been increased from 30 kg per person per day by hand to 3 000 kg / day Processing for 10 hours, calculated at 300 kg per hour), the processing cost per kg of walnut production line is only 1/11 of the cost of manual processing.


2) Reduced walnut kernel breaking rate. Manual smashing is not easy to control due to the strength of the knock. The walnut kernel breaking rate is high when the shell is broken. The walnut shell breaking machine can adjust the shell breaking gap to achieve different types and sizes of walnut shell breaking to reduce the walnut kernel breaking rate.


3) Shell and kernel separation After walnut shell breaking, walnut kernels, shells, and walnut seeds are mixed together and separated by a shell and kernel separator, which lays the foundation for the deep processing of walnuts.


6. Factors affecting the quality of walnut shell breaking and classification


The physical and mechanical characteristics of pecan were measured and analyzed. The test showed that the average diameter of the pecan shell was 20.6mm, the average thickness was 2.2mm, and the sphericity coefficient was 0.98. During the test, the average force of the pecan shell breaking was 265.7N. Displacement of 0.77 mm in the direction of spheroid; the test confirmed that the pecan shell can be extracted into a thin spherical shell with uniform thickness and isotropy. Quantitative analysis of internal forces and displacements of pecan shells using the thin shell theory shows that two pairs of normal concentrated forces are more favorable for shell rupture. Stress analysis from the following pecans shows:


1) Tests have shown that 90% of the three-dimensional dimensions of Changhua pecans are between 17 and 22 mm, the average diameter of the spherical shell is 20.6 mm, the average thickness is 2.2 mm, and the sphericity coefficient is 0.98. Based on the sphericity measurement and physical measurement of shell thickness of pecans, pecans can be simplified into thin shell spheres with uniform thickness.


2) During the test, the average force of pecan breaking shell was 265.7N, and the displacement was 0.77mm. Judging from the analysis results of pecan mechanical properties, the extrusion method and speed have no significant effect on the strength of walnut shell breaking force. Walnut shell is considered to be isotropic.


3) It is found in the test that the pecan extrusion method has an important effect on crack formation. If it is squeezed in the direction of the longitudinal diameter, the crack is mostly along the direction of the suture; when it is squeezed in the direction of the transverse diameter and the edge, the crack direction changes irregularly, but it is basically at a certain angle with the suture. This is beneficial for pecans to break the shell and take kernels. The test only tested the compressive force of crushing the husk, and there is still a certain distance to reach the standard of edible hand-peeled pecan peeling.


4) Using the thin-shell theory, the pecan was divided into two regions when subjected to a pair of normal concentrated forces. The force analysis and displacement analysis were performed, and the internal force and displacement calculation formulas were obtained. When two, three, and four pairs of normal concentrated forces are uniformly applied to the shell, the displacement and compression deformation are quantitatively analyzed using a linear superposition method. It is concluded that under the action of two pairs of normal concentrated forces, the maximum displacement on the shell is 1.57 δ, the internal force generated in the shell is the largest, and the shell is most prone to rupture. Walnut factors: (1) Varieties of walnuts. Due to the variety of walnuts, irregular shapes, large size differences, and small shell-to-kernel clearance, the amount of deformation required for the shell to break completely is greater than the shell-to-kernel clearance, so it is more difficult to break the shell and take the kernel. The gap between the walnut shell and the kernel is large, and the shell and kernel are not tightly connected, and the shell is easily broken and separated. Try to choose walnuts with a thin shell, as this will easily break more whole or half kernels. (2) Fullness and uniformity of walnuts. The size of the walnut is not uniform, and it is difficult to determine the optimal operating conditions of the shell breaking equipment, so that the shell breaking efficiency and powder degree cannot reach the optimal balance, and the shell breaking effect is reduced. In order to improve the shell breaking effect, the process of circulating shell breaking and secondary shell breaking can be adopted. When the particle size difference is large, it is best to adopt the shell breaking classification to achieve a good process effect. (3) Humidity of walnuts. The moisture content of walnuts has a direct effect on the strength, elasticity and plasticity of the shell, and the crushing degree of the kernel. In general, the lower the water content of walnuts, the more brittle the shell.