Numerical Study And Processing Parameter Optimization On Fracture Splitting Of Connecting Rod

Title of Dissertation: Numerical Study and Processing Parameter Optimizationon Fracture Splitting of Connecting RodMajor: Material Processing Engineering.Advisor: Prof. Kou ShuqingThe fracture splitting technology of engine connecting rod is the significantreform for the traditional processing skill of connecting rod as a new kind oftechnology. It was started in developed country in 1990's, and was used in largearea of production. Now, this technology has become the important sign of thelevel of a national manufacturing industry of engine connecting rodAlthough the fracture splitting technology of connecting rod has been acceptedin many mobile manufacture companies both in domestic and abroad, there are stilla lots of problems, including post-splitting, non-splitting, the distortion of splittingface etc. Those problems influence the quality stability of products. But theinfluence percentages on the results of fracture splitting of connecting rod are manymore, for example, the fracture splitting temperature, the fracture splitting velocity,the material character of connecting rod, the parameters of crackle groove, backforce etc. But right now how those influence percentages on the splitting results ofconnecting rod are not obvious. The selection of fracture splitting force parametermainly depends on experience for no theory to abided by. To stop non-splitting, wealways choose the larger fracture force in equipment design, so this leads to a lineof problems such as equipment energy waste and process quality problems. Wehave not an accepted argument on these influences: the influence of prefabricatedcrack groove's geometry shape on fracture force; the influence of extra inertia forceand back force on the fracture splitting of connecting rod. So those skills have beenthe key technics in fracture splitting of connecting rods such as the analysis offracture splitting of connecting rod, finding the influence order of thosepercentages on the results of splitting of connecting rod, selecting the reasonablecrackle groove parameter, cutting down the fracture force.By make use of fracture splitting numerical simulation to the fracture splittingprocess analysis of connecting rod, this paper explores influence order of variedpercentages on splitting results of connecting rod in the fracture process and makesa forecast and corrects fracture force of connecting rod. It's purpose is to improvethe quality of fracture splitting connecting rod by the optimization design oncrackle groove, the reasonable selection on fracture force parameters, andimprovement equipment processing precision and function.The main work and achievements of this paper are as follows:1.The decision of boundary J integral on a kind of connecting rod materialcalled C70S6.By the help of the Finite Element Method numerical simulation software, thispaper works out the relation curve between the J integral standing for C70S6 steel'scharacter (a new fracture connecting rod material) in static state of connecting rodand the extra force. To ensure accuracy, a static state tensile test of connecting rodreaches the real fracture force is 72.395KN. Then comparing the real force with thesimulation curve, we can forecast the boundary J integral is 2.88N/mm for C70S6forged steel.2. The fracture splitting process simulation of connecting rod and fractureimperfection analysis.A static state fracture splitting numerical simulation for saloon and truckconnecting rod has been finished. Through analysis of the stress distribution on thecrack groove tip before the splitting of the connecting rod, we found the reasonwhy quality problems appearing. It is the disorder of crack tips lead to dissmooth-faced, segregation of cracks even dropping dregs. And this result is fairlyconsistent with practical experimental result.3. The forecast of fracture parameter, the reasonable design on prefabricatedcrackle groove and the decision on geometrical modulus.Successfully carry out numerical simulation on connecting rod model ofprefabricated crackle groove with different opening angle, curvature radius and thegroove depth. Threshold value of fracture force of each model comes out by J...