| In order to solve the problem that secondary pollution could be caused by separating the cutting and stirring during harmless disposal of animal carcasses,The paper,combining the characteristics of the shredder and the mixer,designs a kind of cutting blade that could simultaneously complete the function of cutting and stirring,and it will be used for harmless disposal of animal carcasses carrying pathogenic bacteria.By analyzing the cutting principle,the blade is designed with circular arc to achieve the "sliding cut" effect;The equipment adopts the indirect heating method of conducting heating oil,which has the advantages of high stability and good heat transfer.The performance test showed that the blade could basically complete the function of cutting and stirring and meet the requirements of the standard of organic fertilizer of NY525-2012,but harmless disposal takes too much time,resulting in high consume but low effect,Moreover,it is easy to be broken or deformed due to overload.The slow heating results in a long period of low mid-temperature in the fermentation chamber,which led to fecal coli-group temporarily increased rapidly during high temperature sterilization.The main reason is related to lower cutting and mixing efficiency;It was found by measuring the inlet and outlet temperature / heating rate and volatility of temperature that slow heating and uneven temperature distribution are also indirectly or directly related to cutting and stirring performance.In order to further improve the harmless processing capacity and better achieve high efficiency and low consumption,in this paper,the main problems of the equipment in the performance test are improved as follows.It could improve the ability of cutting and stirring at the same time by welding the spiral blade on the agitator shaft,furthermore,the direction of turning of the spiral blade is in the opposite direction of the tilt of stirring plate.It could further improve the ability of cutting by welding arc blades on both sides of the blade,and the center of the arc blade coincides with rotation center of the cutting blade.Finally,the stirring plate is changed from "upright" to "inclined",which could increase the contact area between it and material in order to improve the mixing ability and reduce the resistance.The parameter optimization of the blade and the simulation of cutting performance was carried out by using the discrete element software EDEM.Intrinsic parameters,contact parameters and contact model parameters were obtained by parameter calibration of pork and bone to lay a foundation for the simulation of cutting and stirring performance.According to the simulation of cutting performance,The improved blade could cut approximately about 23,079 B-B keys within the effective time of the spiral blade and arc blades(1.5~2.5s),compared with only 15,979 the original.On average each lap,the improved blade could cut 3550 B-B keys more than the original did,and cutting efficiency is increased by 0.44 times.It is indicated that the cutting performance could be improved by welding the spiral blade and arc blades.A scheme of orthogonal test,which includes 3 factors and 3 levels,was designed by choosing the blade angle,axial plane angle and arrangement as 3 test factor and choosing the percentage change in the standard deviation of the mixing degree and torque routed to the agitator shaft as 2 test index.The experimental results show that the arrangement of the blade has no significant influence on the percentage change in the standard deviation of the mixing degree,and the blade angle and axial plane angle have a significant influence,among them,the blade angle is more significant than the axial plane angle;The results show that 3 test factor have significant influence on the torque routed to the agitator shaft,among them,the influence of the arrangement of the blade is the most significant and the effect of the blade angle is the least significant.In order to ensure high mixing and low consumption,this paper will consider the trade off that the level of factor 1,factor 2 and factor 3 are all 2.So,the optimum level of factors determined by orthogonal test was A2B2C2.According to the simulation results of the mixing effect of the equipment optimized,compared with the original model,torque routed to the agitator shaft was reduced by 39% and the mixing ability was increased by approximately 20%,which also shows that the optimum level of factors determined by variance analysis is reasonable.On the other hand,considering the different requirements of cutting pork and cutting bone,in order to improve the cutting efficiency of Animal Carcass,This paper designs a kind of self-adapting cutting the blade,which automatically replace the blade according to the type of the cutting object.At the same time,arc blades,cutting blade,the stirring plate and other vulnerable positions are divided into Independent parts to facilitate timely replacement and improve the service life of the equipment.Finally,there is a problem of vibration of equipment during the performance test,so ANSYS software in finite element method is used for the mode analysis of the rack to slow down the vibration.Through the analysis of the former 6 modal vibration modes and natural frequency,it is showed that the former 3 natural frequency of the original rack are between 18.19 Hz and 28.46 Hz,which is relatively close the excitation produced by the motor and resonates easily;The latter 3 natural frequency of the original rack between 40 Hz and 47 Hz.Although them deviates from the external excitation frequency,the natural frequency is concentrated,which could easily lead to the resonance superposition;This result is in line with the performance test.The natural frequency of the former 6 natural frequency of the improved rack is between 44.73 HZ and 143.63 HZ.Although it is similar to the modal vibration modes of the original rack,the natural frequency of the former 6 natural frequency of the improved rack is obviously deviated from the external excitation,which could avoid resonance.And the difference between those natural frequency is quite great,which would reduce the possibility of resonant superposition.To sum up,the improved rack could reduce the vibration of the equipment. |
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