| The bogie frame is the main carrying part of locomotive, the welding residual deformation of the side beam is the key factors effecting production quality. So the quantitative predicting of welding deformation regularities and, thereon, taking the optimal quality-control measures, have theoretical values and engineering significance in the integral design, manufacturing technique selection and the service security evaluation of the side beam welding structures themselves, as well as other kinds of welding structures.In this dissertation, first, based on thermal elastic-plastic coupling method and inherent strain method, the welding residual deformation’s numerical simulation was done respectively for the side beam model, and compared with experimental measurement result. Then, on this basis, for the process parameters of controlling welding deformation, a series of investigations were made, optimal process parameters have been got by optimization analysis. The study works and achievements are summed up as follows:1. The inherent strain method has been corrected. Take a welded T-joint as example, the formation mechanism of fillet weld’s angle distortion was studied by combining thermal elastic plastic analysis with mapping strain component method. The results show that the main source of fillet weld’s angle distortion is the inherent shear strain but not the transverse inherent normal strain. Then, based on the view, two different loading direction that influence transverse restraint degree、transverse inherent strain and residual angle distortion were analyzed. The result made by the diagonal load along weld’s surface is closer to the practical measured values and thermal-elastic-plastic simulated values, it indicate the rationality of the diagonal loading along weld’s surface.2. The three-dimensional numerical analysis model was established. According to the establishment current welding parameters and sequence, The numerical model was loaded and analyzed, and transient temperature field throughout the welding process was got. Based on the transient temperature field, thermal elastic-plastic coupling numerical analysis has been done, and welding residual deformation analysis using inherent strain method has been made also. To validate the fitness of two simulation methods, the actual welding deformations are measured after experimental side beam welded, and by contrasting simulation value with measured value, it was found that the main factor of the side beam welding residual deformation is the external four longitudinal weld, deformation law of three results are consistent with each other; the error between the result of thermal elastic-plastic coupling analysis and measured value is less, within10%.3. Based on the thermal elastic-plastic simulation method, the laws of welding deformation caused by the welding sequence and direction of the external four longitudinal weld were analyzed by optimization method. In order to optimize the welding sequence and direction(nonnumeric variable), the concept of pointer and stack of C language programming were referenced, the combination and order were generated, saved them in the array, therefore, the optimization analysis of pointer variable was equated with the optimization analysis of welding sequence and direction.4. Based on orthogonal test, the schemes obtained by pre-analysis were extracted, then, the datas formed orthogonal experiment table comprising four-factor three-level. Through the orthogonal-test analysis, the important order of the various factors effecting residual welding deformation is found, as well as optimum scheme. The welding sequence of the first layer and the second layer play an important roles on the welding residual deformation, and is the main factors of the welding residual deformation. The different "optimum" schemes of vertical bending and side bengding were respectively obtained, after comprehensive analysis the optimum scheme was determined. The optimum scheme can make vertical bend deformation reduce about18.9%, and make lateral bend deformation reduce about9.5%.5. Because the side beam is asymmetric, and the external four longitudinal weld locate four corner of longitudinal neutral axis(X axis) of the side beam. For the groove weldment, the shrinkage of weld metal is the main factor making residual welding deformation. Based on analysis above, when the main welds were welded, it was supposed that surface pressure value and direction of the reverse-deformation were different each other.Compared with the reverse-deformation method of the uniform surface pressure value and direction, the new method is called as one by one reverse deformation method. Through comprehensive analysis and evaluation, it was determined that the twenty-ninth scheme of the optimizing sequence is as the optimum scheme. The vertical bending value of the optimum scheme is+4.87mm, compare with+6.18mm of the vertical bending value without reversible deformation pressure, the quantity value is decreased by21%, and the side bengding value is+10.34mm, compare with-10.78mm of the side bengding value without reversible deformation pressure, the quantity value is slightly decreased, and it is important that the bending direction is changed, the opposite direction with the welding residual deformation of the intenal welds.6. Butt plates welding was as an example, the DC-LSND numerical simulation was done, then,test-part was measured, the computation result was founded basically consistent with the measured data, therefore, through process control, the welding effect of low stress no-distortion can be obtained.7. The L of the distance between arc and heat sink is one of main parameter influencing the control effect, as well as the h of the heat sink intensity. With T-shape single slope groove welding beam as an example, the optimal value about h、L were acquired by the optimization analysis. Compare the result of the DC-LSND welding’s optimum scheme with the result of conventional welding, because of the action of heat sink, the displacement of Y-direction is decreased by43.7%, the displacement of Z-direction is decreased by47.0%. Compare with the difference of the orthogonal experiment table, it is indicate that the h of the heat sink intensity plays a major role, whereas the L of the distance between arc and heat sink is the secondary factor. Through analysis and calculation, the change curves that δ (transverse displacement)and μ (vertical displacement)of the displacement value was variational with the parameters changing of the heat sink have been respectively gotten. Based on the change curves, the best range of the h is [0.004,0.2] W/mm2K, the best range of the L is [15,30]mm.8. For controlling the welding residual deformation of the side beam, the welding deformation law by the combined effect with the welding sequence and direction and the reverse-deformation is researched. When the welding residual deformation caused by Internal welds was been calculated in advance, together with the combined effect of optimal parameters, after all welds were been welded, the amount and direction of the welding residual transverse displacement δ in middle part of side beam is+2.64mm, and vertical displacement μ is+1.46mm. Compared with the welding residual displacement withou control measures, it can make lateral bend deformation reduce about84%,and make vertical bend deformation reduce about73.8%, and make bending direction change. And, the node average displacement evaluating bend in middle part of side beam is less than3mm. |
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