Simulation Of Process Of Notch Cutting By WEDM And Influence Analysis Of Technology Parameters

Electrical discharge wire-cutting notching is one of the core processes of fracture splitting of connecting rod, and after cutting notching, many factors such as structural mechanical state, crack distribution region, crack condition and amount and residual stress, directly impact on the following process. Therefore, several activities such as analyzing the strained condition in the process of electrical discharge wire-cutting notching of connecting rod, discussing how the crack has influenced the technological process, have shown the essential theoretical significance and construction value in terms of optimizing, controlling and improving technological process and equipments.The method of combining simulation and experimental analysis was primarily adopted. Firstly, in the condition of external load (cutting) multi-physics coupling (temperature field and residual stress field), the structural force and response was analyzed, and the process and mechanism of cracks was analyzed as well. Furthermore, the relationship between the technological process parameters and crack state was established. The paper mainly includes.1. Establishment of heat load and boundary conditions in the analysis of temperature field. Simulation method was adopted to compare the applying characteristics and circumstances of various heat source models, the heat resources model which was suitable for electrical discharge wire-cutting notching simulation calculation, was chosen and then improved, therefore, a better three dimensional cylindrical heat source, which demonstrated the specific process of electrical discharge wire-cutting notching, was improved and finally achieved the simulation application.2. The finite element model of connecting rod local structure was built up, and the thermal-structure sequential coupling method was used, so as to achieved the analysis of temperature field and stress field of workpiece in the process of electrical discharge wire-cutting notching which based on element birth and death. The results show that under the heat load and residual stress, along with material corrosion, the heat stress in the edge weak region of splitter exceeded the tensile strength of materials, which end up in cracks.3. The stress of local structure act as boundary conditions in the process of splitting simulation, the crack distribution was simulated and then the splitting process simulation which based on residual stress was conducted, subsequently the structural crack initiation with residual stress field was calculated, at the same time, the stress state of local structure was used as initial condition of following micro-simulation.4. The numerical simulation results of multiple condition splitting process were compared and analyzed, then the impacts that different peak current or impulse duration had imposed on stress of electrical discharge wire-cutting notching, crack distribution and cracking process were studied, and at last the relationship between technological parameters of spark discharge and cracking process were established.