Study On The Welding Process And Its Deformation Control Technology For The Cylinder Body

Because of the large size of the cylinder of marine low-speed and high-power diesel engine, when producing with casting process, and the production cost is high, and it's easily to have casting defects, difficult to repair and easily to cause high rejection rate; therefore it's meaningful to exploit a new production process of cylinder to meet the requirement of high quality, high efficiency, low cost of high-power diesel engine. Based on this,a process research of welded cylinder was put forward. As the first welded cylinder body of research and development manufacturing, After testing a large number of welding process, developed a cylinder weld roof layout and related welding parameters; developed a cylinder block of the box structure of the welding sequence, turning the form of the number of joints; and for scavenging device C plate, and S plate assembly and welding; to complete the entire marine low-speed high-power cylinder welding.Roof for cylinder welding technology requirements, design the work piece and welding groove type analog parts, the CMT mode, by the orthogonal test, compared o the weld shape under different process, reasonable distance applied in narrow gap welding were determine, and problem of interlayer fusion was solved also. Through the test of fillet weld, the inclination of the gun to solve a penetration of the narrow gap wall was determined. Through the experimental research of TANDEM double wire welding process, a mathematical model of swing welding was established., which proposed a method of controlling welding layer thickness and thus provided the basis for process testing; through the process study,the relationship between swing amplitude, swing speed, the residence time of both sides, the welding current and formation of weld were studied. Showing CMT carbon dioxide used for cylinder gas shielded arc welding low cost, flexible operation, low heat input, suitable for roof welding cylinder.Completed a cylinder temperature field and stress field test result shows the temperature field and stress field distribution, the numerical simulation provides a reliable basis. Cylinder temperature field tests show that, due to the lower plate temperature, component greater heat loss faster, test points far from the weld, the curve of temperature is not high; stress test results show that the roof and sides of the welding residual Similar stress distribution, parallel to the weld direction and the direction perpendicular to the seam welding residual stressσy are slightly larger thanσx; perpendicular to the weld direction, with the marginal increase from the weld, residual stressσy andσx have significantly decreased; the same time, the stress test results before and after annealing show that the annealing process can considerably reduce the welding residual stress, the stress field changed.The welding process was simulated in the ANSYS environment and the physical model, material parameters, unit type, meshing, the welding heat source model respectively were made a detail analysis for the measures should be taken with an appropriate finite element model. The analog parts of welding temperature field was calculated, though the analysis and comparison of the results and the actual testing of welding temperature field simulation of parts, it was found that three test point measurement curve and calculated curve of the same general trend, which verified the calculation approach was reasonable. On this basis, welding stress and strain field were calculated, and a reference for reducing the welding residual stress and deformation was proved through optimization of the welding sequence.