Research On Calculating Model And Software For Insulating Riser Of Large Steel Castings

Shrinkage cavities and shrinkage porosities are easily produced in the solidification of large steel castings due to body contraction. By means of insulating risers, these defects can be eliminated, the efficiency of riser feeding can be improved and the liquid metal can be saved. Lots of calculating models are suitable for technological design of insulating risers. At present, it has become an urgent problem whether to choose a suitable calculating model, optimize the prime parameters in the calculating model and design a relevant calculating software for insulating risers in order to guide technological design of insulating risers for large steel castings.In allusion to two kinds of classical casting steel ZG0Cr13Ni4Mo and ZG230-450 and two kinds of insulating materials such as insulating brick and insulating plate, calculating models of insulating risers for large steel castings are researched, in which the prime parameters are optimized. A calculating software for insulating risers of large steel castings is designed according to the calculating model. The accuracy of the calculating software is verified by numerical simulation for solidification of large casting steel machine frame and by test experiment.In terms of calculation principles, limiting conditions, applicability and calculated results, advantages and disadvantages of Q-number Method, Perimetrisehen Quotient Method and Cubic Equation Method are discussed in detailed by research methods such as numerical calculation and drawing analysis. It is found that the Cubic Equation Method has more sufficient theoretical basis, wider applicability and more accurate calculated results as the calculating model for insulating risers of large steel castings. The calculating model of Cubic Equation Method for insulating risers of large steel castings is deduced, and six parameters in the calculating model are researched.In the calculating model, the'of the insulating brick is optimized by the measurement experiment for thermo-physical parameters and by the computer numerical simulation technique. It is obtained that the range of'of insulating brick is between 0.7463 and 0.7576. For safety, the'of insulating brick is taken as the value of 0.7576 in the calculating process. The'of the insulating plate is optimized by the modulus relationship between Foseco insulating risers and sand risers in the same size. The range'of insulating plate is between 0.7813 and 0.8064 after the optimization, and the value of'of insulating plate is taken as 0.8054 through the linear fit. The calculating software for insulating risers of large steel castings is established by MFC based on the dialog class. The insulating risers made of insulating brick, used for the large ZG230-450 machine frame, are calculated through the calculating software. Then, the numerical simulation experiment is carried out for the solidification process of the machine frame, and the distribution of shrinkage cavities and shrinkage porosities in the machine frame is predicted. It is found that the insulating risers designed by the calculating software can meet the demand of the machine feeding, that is, the size of insulating risers designed by the calculating software is accurate. Further, the accuracy of the calculating software for insulating risers of large steel castings is verified by the casting experiment and the ultrasonic flaw detection. To the insulating risers for large steel castings designed by the calculating software, the efficiency of riser feeding is raised by 4.7 percent, and the rate of qualified castings is increased by 17 percent. Otherwise, the calculating software for insulating risers of large steel castings has lessons and guidance for the technological design and calculation of insulating risers used for other kinds of cast steel.