| Barrel finishing technology is a type of fundamental mechanical process manufacturing technology.The goal is to enhance the quality of the surface parts and the integrity of the surface parts.This technology is widely used in the surface treatment of high-performance parts and complex surface parts due to its advantages such as high degree of conformity with the requirements of surface quality integrity,good performance of processed parts,strong applicability of processing range,low processing cost and environmentally friendly processing process.Expert Cariapa pointed out that about 50% of the machined parts worldwide use a barrel finishing process to improve the surface quality of the parts and improve the surface integrity of the parts.The barreling and finishing process needs to consider the essential elements such as the processing objects and requirements,processing equipment and parameters,the type and shape of the roller finishing media,the size,and the chemical agent.Each element affects and restricts each other.Therefore,barrel finishing technology system is a complex system.Faced with the changing and diverse requirements of finishing parts,especially critical parts for high-end equipment manufacturing,the traditional model of experimenting and exploring based on experience to formulate the optimal process plan cannot meet the requirements of the current rapid development of manufacturing.With the advent of the discrete element method,according to the characteristics of the barrel finishing process,the discrete element simulation technology is used to realize process simulation,which can reduce or replace complicated process experiments.Among them,the EDEM software has provided great help for solving practical engineering problems.Several researchers have applied it to numeric barrel finishing simulation.However,the degree of coincidence between the simulation and the actual work conditions is not determinable in the absence of quantitative data,and it is difficult to use the discrete element simulation in shaping the process plan.They are considering that the huge calculation scale when using the discrete element method for simulation will directly affect the simulation efficiency.The rapid growth of computing power will not be able to meet the growing demand in practical applications.The quantitative relationship between the scaled models realizes the use of physical models to predict the original model.The solution to this problem is to first discuss the contact force in simulation and experimental testing between the roll polished media and the workpiece and different implementation models(contact model,material removal model)for comparative study.This topic is aimed at the spindle-type barrel-finishing process,combined with the comparative analysis of the discrete element method simulation and experimental test,to study the core element theoretical model and experiment of the spindle-type barrel-finishing process simulation system,so as to the follow-up provides a useful reference for the development of the actual process of barrel finishing.First of all,the design and construction of the same device and process parameter environment for experiment and simulation.Taking into account the requirements for the accuracy of physical parameters during the simulation process,the universal compression testing machine is used to test and obtain the intrinsic physical performance parameters of the processing medium.The sliding plate test is used to determine the physical performance parameters between the barrel finishing medium and the workpiece,and the stacking angle of the medium is tested by the injection method.Based on the method of orthogonal test,combining experiment and simulation is used to compare the physical performance between the tumbling medium.The performance parameters are calibrated,and the Plackett-Burman test in Minitab software is used to screen out the significant parameters that affect the angle of repose,combined with the steepest climb test to determine the optimal region of the significant parameters,and analyze by response surface method to determine the optimal parameters combining of parameters,obtained the physical performance parameters between different sizes of spherical roller finishing medium,and provided an effective measurement and calibration method for the setting of discrete element simulation simulation contact parameters.Through quantitative analysis of the workpiece clamping position,roller speed,contact speed between the grinding media and the workpiece,the influence of the grinding media size on the contact force,based on the elastic contact force and elasticity between the rolling finishing media and the workpiece in Plastic contact force solution,Newton's second law,Krabbe-Elon's theorem and the law of conservation of energy to quantify the contact material,the clamping position of the workpiece,the collision contact speed between the roller finishing media and the workpiece,and the size of the roller finishing media.The influence coefficient of the contact force between the media and the workpiece depends on a large amount of simulation data and experimental data,through mathematical fitting and approximation calculation,The contact model between the barrel finishing medium and the workpiece under different process parameters is constructed.Considering that the influence of each factor on the contact force is different,in the decision of the process parameter selection,it is to select the best process parameter combination based on the analytic hierarchy process,the analysis process of the spindle-type barrel polishing and finishing contact model is further systematized,mathematicized,and modeled,and the relationship model between the contact models is established.The contact force between the finishing medium and the workpiece provides a theoretical basis.In order to experiment with the evaluation and prediction of the material removal amount of the spindle-type barrel finishing,the Hertz-Mindlin with Archard wear contact model in EDEM was used to simulate the material removal amount of the workpiece,combined with the simulation simulation between the rolling finishing media and the workpiece The contact force and the tangential velocity of the grinding media relative to the workpiece are used to establish a material removal model between the amount of material removal and the time and the clamping position,and combine the experimental test to verify the correctness of the model to further illustrate the feasibility of simulation;at the same time,consider the influence of the surface processing The main factors of the effect,the surface roughness and the surface topography of the workpiece after the finishing experiment are used as evaluation indicators to explore the main factors affecting the surface processing effect of the workpiece.It provides a core and effective method for the comprehensive evaluation of the effect of the spindle-type barrel finishing process.A scaled-down model is studied to speed up the simulation and to reduce the complexity of simulating millions or even ten millions of rolling grinding medium when the barrel finishing equipment of the spindle-type process workpiece in an actual environment.The model can replace the prototype for testing.According to the principle of process similarity,a set of scaling laws for discrete element models is proposed.According to the principle of geometric and mechanical similarity,a set of scaling theories for discrete element models are proposed,and the unit conversion or scale factor of a single physical quantity involved between the physical model and the scaling model is analyzed.Establish simpler and general scaling laws to control the precise scaling of discrete element models and lay the foundation for the development of the spindle-type barrel finishing.This paper provides theoretical support and application strategies for the construction of the spindle-type barrel finishing process simulation system and the core element correction theory for the barrel finishing process industry. |
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