Optimization Design Of Engine Cylinder Block Casting System Based On Numerical Simulation

With the development of variable turbocharging technology and high pressure common rail direct injection technology,users are increasingly demanding diesel engine power,compactness,casting shape complexity and heat load,key materials and manufacturing for diesel engines.Technology also puts forward higher requirements.The traditional HT250 material can no longer meet the needs of the diesel engine body,and it is urgent to develop a higher performance,more stable and reliable diesel engine body material.At the same time,with the development of high-end low-emission diesel engines,the structure of the diesel engine body is more and more complex,and the dimensional accuracy of the internal cavity is significantly improved.The traditional HT250 casting process can no longer meet the casting molding requirements of new high-performance body materials,and is urgently developed for new The casting process of the material.Based on Cu-Cr-Mo-Sn and Cu-Cr-Mo-Ni alloy systems,the four-factor and three-level orthogonal experiments were used to study the microstructure and tensile properties of alloyed cast iron with different alloying elements.And the influence of hardness,using electron microscopic analysis to analyze the fracture mode,crack source and fracture mechanism of the alloy.On this basis,the composition and composition of the alloy were optimized,and a new high-performance alloy gray cast iron material was developed.At the same time,according to the solidification and shrinkage characteristics of the new alloy gray cast iron material,the casting process of D]2 engine block is designed and optimized by digital simulation and verification.The test results show that the alloying elements Cu,Cr,Mo,Sn or Ni are added to the gray cast iron.The content of pearlite in the alloy increases,and the graphite distribution is more uniform and fine.In the Cu-Cr-Mo-Sn/Ni system,the Cu-Cr-Mo-Ni system exhibits better comprehensive performance,and the order of influence on the tensile strength and elongation of the alloy gray cast iron is Mo>Cr>Ni.>Cu.According to the orthogonal test results,the new high-performance alloy cylinder material is optimized,and its chemical composition is C-3.40%,S-0.08%,Si-1.90%,Mn-0.80%,Cu-0.8%,Cr-0.3%,Mo.-0.2%,Ni-0.6%,the casting tensile strength reached 315 MPa,the elongation was 0.87%,and the hardness was 228(HB).Its tensile properties and casting process performance meet the needs of new diesel engines.According to the new cylinder material,based on the traditional HT250 casting process,three casting process schemes for D12 engine block are designed.The AnyCasting simulation software is used to simulate the casting process of the three schemes,simulate the filling process of the alloy,solidification process,Formation,distribution and control of casting defects.Turn out:The traditional HT250 casting process(Scheme 1)has many casting defects and cannot meet the requirements.The simulation results of the second scheme are slightly improved compared with the first scheme,but there are still large areas that may have defects.On the basis of the second scheme,the addition of the vertical runner and the extended runner are optimized to form the third scheme.No obvious casting defects are found during the simulation,and the requirements for trial production are basically met.According to the simulation optimization of the casting process,the mold of the D12 cylinder was designed and processed,and after 300 batches of trial production and processing verification,it was found that the scrap rate of the D12 cylinder prepared by the new scheme has been reduced by about 53%of the conventional scheme.Up to 4%,to meet the production requirements.