Research On The Key Technologies Of Poultry Egg Cushioning Packaging

In the world,China is the country with the largest egg production and consumption.However,during the collection,cleaning,testing,packaging,storage and transportation of eggs,the eggs were subjected to extrusion,collision,vibration and impact in the different degrees.The breakage rate of eggs was more than 8%,the broken eggs were easily corrupted and cause infection of other eggs.Unreasonable packaging was not only ineffective in protecting eggs,but also a large number of eggs were damaged during the packaging process.In addition,the traditional semi-mechanized packaging had low efficiency and couldnot meet the needs of high-throughput egg processing production lines.Due to the problems of high breakage rate and low operation efficiency in the packaging process of eggs,this paper systematically studied the eggs,the inner packaging and the outer packaging of eggs,and analyzed the damage principles of eggs under external forces,such as falling,vibration and pressure.Similarly,this paper discussed the cushioning effect of the inner and outer packaging of eggs in various forms,as well as the influence of key parameters in packaging on egg breakage,such as packaging brittleness,resonance frequency,acceleration transmissibility,etc.According to the analysis and test results,an in-cut and low-damage inner packaging box was designed,and a boxed egg packaging production line based on a Cartesian coordinate manipulator was developed.This production line had been put into use and could realize various sizes of packaging.The boxed eggs were flexibly put into the box,which realized the automation of boxing and sealing of eggs,and the efficiency was 4-6 times that of manual operation.The main research contents,results and conclusions were as follows:（1）The mechanism of egg damage was analyzed using ANSYS analysis software and destructive test method.With the help of the test equipment TMS-PRO texture analyzer,the ultimate average rupture forced at the tip,equator,and blunt end of duck eggs were obtained as 49.12 N,20.45 N,and 43.29 N,respectively.The ultimate average rupture force of the egg tip,equator,and blunt end was 53.52 N,23.42 N,and 39.93 N,respectively.The egg tip had the strongest bearing capacity,which was larger than the blunt end and much larger than the equator.With the increase of the loading speed,the resistance ability of each loading direction decreased.A 3D laser scanner was used to collect the point cloud data of the outer contour of the egg,extract the outer contour curve,and reconstruct the egg shape model.The finite element analysis was carried out to simulate the free fall of eggs and the stress state of eggs in flow-through packaging.Under the same restraint and load,the maximum displacement,stress,strain and deformation energy of the small tip of the egg were concentrated at the point where the load was applied.Under the distributed load,the maximum displacement was at the applied load.The uniform load distribution area could greatly reduce the local displacement,stress,strain and deformation energy of the eggshell.The correlation between the stress of each point on the egg and the shell wall thickness t and egg shape index m was analyzed using the Huggenberger theory,the stress law of each point was obtained.The stress law of each point was obtained,the stress of the small-headed eggshell increased when m increased,and the stress decreases when t increased;the local buckling and deformation of the small-headed thin-walled eggshell was caused by the increase of the circumferential compressive stress of the ellipsoid shell.The large end was similar to a spherical shell,and its axial stress and circumferential stress were similar in magnitude,and it was still a sphere after deformation.（2）According to the buffer mechanism of packaging materials,a new inner packaging box for eggs was designed and verified.The constitutive equation of the contact between the egg and the inner package and the egg drop impact model were constructed.Based on Hertz formula,the influence degree of egg buffer packaging material properties on contact stress was discussed.The greater the elastic modulus and the Poisson’s ratio of the buffer material,the greater the contact stress.The larger the curvature radius of the packaging structure,the smaller the contact stress.The internal contact stress was smaller than the external contact stress.C6 was a single column transparent packaging box that could hold 6 eggs,C12 was a double column transparent packaging box that could hold 12 eggs,X6 and X12 were the control packaging boxes respectively.According to the condition of non-penetration,the inner packaging boxes C6 and C12 with low breakage rate were designed and manufactured.The buffering protection performance was verified by experiments.The results showed that the polygonal column of the thin-walled egg box was better,the inner-cut sidewall design was better than the outer-cut design,and the sidewall inclination angle of 50°～65°was better.Comparing the new structure C6 with Packing box X6,the load resistance of empty box and full box had increased by 31.58%and 29.9%respectively.The breakage rate during transport was reduced by 0.72%.In the double-column C12 new structure packaging box,the mean maximum compression yield force of the empty box and the full box were 440.24 N and 586.72 N respectively.The anti-load capacity was 171.58%and 227.88%of the control package X12 respectively.The new structure had better cushioning performance and the load-carrying capacity was significantly improved.（3）According to the basic principles of dynamics and the theory of brittle value of drop damage,the shock vibration model of egg packaging was established.In the environment of drop,vibration and pressure,the influence of outer packaging on the damage law of inner packaging eggs was analyzed and verified.According to the ASTM D5276 test standard,the PDL 227 drop tester was used to compare the surface,edge and corner drop test of the outer packaging box,and measure the brittleness value of the X12and C12 packaging.The following conclusions were obtained:the surface drop was the main drop method that caused the egg to break,and the acceleration response on the egg was much larger than that of the corner drop and the edge drop.The egg drop brittleness value could be obtained by the surface drop method.The drop safety height of the new structure C12 packaging box had increased by 184%,and the brittle value had increased by 222%.MTS 840 electro-hydraulic vibration table was used to study the damage law of C12 outer packaging box and X12 outer packaging box under two excitations with G_rmsof 0.52 g²/Hz and 0.73 g²/Hz.The breakage rates of eggs in X12 boxes were 0 and14.58%respectively,and the breakage rates of C12 were all zero.The vibration level had a significant effect on the acceleration transfer rate and breakage rate of eggs in the package.Using the PT-8216 carton compression test system,the compression effect test under pre-pressure was carried out on the existing four kinds of outer packaging boxes.Using four kinds of outer packaging boxes,such as PVC inner packaging box,pulp（CH）inner packaging box,polystyrene foam（EPS）inner packaging box and polyethylene foam cotton（EPE）liner,the compression test was carried out under a predetermined load,the results showed that no eggs were damaged.It showed that the outer packaging had a good pressure bearing effect,and the outer packaging under static pressure was not the direct cause of egg damage.（4）An automatic flexible production line was designed and trial-produced,which was based on Cartesian coordinate manipulator and PLC-controlled boxed eggs into boxes.The resonant frequency range 10-15 Hz for this production line should be avoided,the excitation of the conveying mechanism system must satisfy G_rms≤0.73 g²/Hz,and the safe height of the Cartesian coordinate manipulator to release the boxed eggs should be less than or equal to 290 mm.The clamping force of the manipulator to the inner box was less than or equal to 870 N.The actions of the stepper motor and cylinder on the automatic packaging production line were controlled by PLC.The action of clamping,carrying and releasing the egg carton was completed according to the designed path.Cooperate with the conveyor line and the automatic carton sealing machine,the boxed eggs were automatically put into the carton.The operation results showed that the egg breakage rate in the whole process of the production line was 0,and the efficiency of completing 4 boxes and 6 boxes of eggs into boxes was 5.23 times and 4.76 times that of manual boxing,respectively.