Application Research Of Welding Parts In Machine Tool Green Design

With the improvement of environmental protection requirements,green design and manufacturing have become the key technologies for realizing ecological industry and sustainable development.The welding parts have the advantages of short production cycle,light weight,low cost,simple equipment and fast modification.In some cases,they have gradually replaced the casting parts in the green design of the machine tools.Slide carriage as the key component to connect the columns and beams,has a great impact on the performance of the machine tool.Therefore,in this paper,the slide carriage of five-axis gantry machining center was taken as the research object.The static and dynamic characteristics of the welding parts and the casting parts were analyzed and compared.The green design evaluation model was established and the two designs were evaluated comprehensively.In addition,T-welding plate was taken as the research object.The effects of the welding sequence on the deformation and residual stress were studied.By comparing the analysis results,the optimized welding sequence was obtained.Finally,the design of welding parts was applied to the green design platform of machine tool.The main research contents are as follows:(1)The slide carriage of five-axis gantry machining center was taken as the research object,and the welding part was proposed to replace the casting part.The static and dynamic characteristics of the welding slide carriage and the casting slide carriage respectively were analyzed.The accuracy of the finite element model was verified by the modal test.By comparing the analysis results of the two slide carriages,it can be concluded that the low-order natural frequency of the welding slide carriage is significantly higher than that of the cast slide carriage.The first natural frequency increased by 149%,and the maximum deformation of the welding slide carriage was reduced by 76.8%.Therefore,for a single piece,the static and dynamic properties of the welding parts are better than the casting parts.By comparing the static and dynamic characteristics of the machine tool before and after replacing,the results showed that the performance of the machine tool improved to a certain extent after the replacement of the welding carriage.Based on the above analysis,the applicable scope and conditions for the welding parts replacing the casting parts can be summed up.(2)In order to comprehensively evaluate the machine tool designs,the evaluation index system including the performance,cost,time and resource environment was built.And the weight determination method was put forward.A comprehensive evaluation model of machine tool design based on fuzzy AHP was established,which solves the problem of the subjective judgment fuzziness and consistency test of the judgment matrix for traditional analytic hierarchy process.By comparing the comprehensive evaluation scores of the welding design and the casting design,it was concluded that the welding design of five-axis gantry machining center was better.(3)Aiming at the welding deformation and residual stress in the welding process,the T-welding plate was taken as the research object.The finite element models of temperature field and stress field were established.The temperature field and stress field of the welding process were simulated by the indirect coupling method.For the characteristics of T-welding plates,the heat source is used as the heat treatment inside the weld unit,and the load is applied in the form of the heat generation rate.Meanwhile,the filling process of the metal is considered,and the birth-and-death unit method is used to simulate the welding formation process.Three different welding sequence schemes were proposed.Through the simulation of the welding temperature field and stress field,the influence of welding sequence on the welding deformation and residual stress was studied.By comparing the maximum deformation and residual stress corresponding to the three welding sequences,it was concluded that the symmetrical welding was the optimal welding sequence of the T-welding plate.(4)In order to realize the digitization and intelligence of the green design of machine tools,a green design platform for the machine tool was established.According to the demand analysis of green design process for the machine tool,the platform has designed five function modules,which included the user Management,parts query,welding process optimization,CAE analysis and the comprehensive evaluation of machine tool green design.The database which supported the operation of the platform was also established.The development of the platform will help designers to use the existing design information to complete the development of new machine tools more quickly and effectively,improving the market competitiveness of enterprises.