The Structure Improvement Study Of Plastic Snap Joints In Engine Cylinder Block Tray

Plastic buckle is as fasteners are used in a large number of industrial product design,compared with metal fasteners,it have a lot of advantage such as light in weight、corrosion preventive、fastening connection without welding、screw glue and complex technical as well as extra auxiliary tools to complete the assemble,due to plastic snap joints is fabricated with injection molded process,so the product has many advantages of consistency and strong interchangeability,suitable for mass production,etc.Thus the benefits are able to improve production efficiency and reduce the cost.But the plastic buckle failure cases are frequently found during usage.Failure will greatly reduce the reliability of industry product,decrease customer’s satisfaction,more serious situation will cause enormous economic losses of enterprises.This thesis deeply analyze the failure reason of the plastic buckle of the engine cylinder block tray.Raise the optimization structure of the plastic buckle.The main research work of this thesis as follows:First of all to analyze the failure mechanism of the defects theoretically through failure cases,initially identified the failure reasons,then establish the CAE mechanical model with ABAQUS finite element analysis software for the plastic buckle.To apply the mechanical simulation for plastic buckle assemble condition and working condition..Obtaining the stress distribution and max stress value in each condition.To observe the potential failure position.To improve the inner structure of the plastic buckle after deep analysis.Meanwhile procure the max stress value of the plastic buckle not only improve before but also improve after from CAE mechanical simulation on different assemble holes.Fitting these stress value and get the linear equation.The slope of the linear equation could be learned the change degree,the minor degree of the plastic buckle is more stable.Finally make the mechanical simulation for the optimized plastic buckle.The influence of the process parameters such as fill time、Pressure at V/P switch over、Flow Front Temp and weld lines、maximum shear rate、clamp force and injection pressure are analyze with MOLDFOLW software.Finally apply shock and vibration test for the optimized cylinder block tray.Verifying the improvement effect.