| The welded metal bellows(WMB)for mechanical seals is an elastic compensation element with transverse corrugation.It is an important part of the mechanical seal system because of its advantages such as good sealing performance,high reliability,long service life,and wide application range,therefore,it is widely used in petrochemical,aerospace,metallurgy and other fields.The mechanical properties of WMB have a decisive influence on its performance in the field of mechanical seals,such as the sealing performance,stability and allowable use environment of direct mechanical seals.With the rapid development of various industries,the environmental conditions for the use of WMB are becoming more and more severe.In order to meet the needs of use,the research on welded metal bellows must be intensified.At the same time,welded metal bellows continue to have new waveforms and processing techniques.After being developed,it is becoming more and more difficult to study its mechanical properties with traditional theoretical methods.Based on the structure and material characteristics of the welded metal bellows,combined with the actual working conditions,this paper carries out theoretical analysis,linear and nonlinear finite element simulation analysis of its mechanical properties,designs and completes the stiffness test for verificationThis paper introduces the basic principles and characteristics,basic structure and processing technology of WMB,expounds the development process of the mechanical seal and the current research status of welded metal bellows at home and abroad,and draws up the main research content and research methods of this article.The paper introduces the structural parameters,material parameters and mechanical properties of WMB,Introduces the meaning and calculation principle of stiffness characteristics,and carried out theoretical calculations on the stiffness of welded metal bellows by using the company’s unique engineering approximation formula for product stiffness;introduces the strength characteristics,using the conventional formula of the metal bellows under pressure and displacement in the EJMA standard,the stress of WMB was calculated and checked.At the same time,several main failure forms of WMB in actual working condition are introduced,including loss of elasticity,instability,rupture and fatigue failure.According to the waveform design drawing of WMB,Solid Works was used to establish the three-dimensional model of WMB of three specifications and imported into ansys workbench finite element simulation software.Set the material of WMB in the ansys workbench,and perform the grid division and grid quality evaluation.The axial stiffness of WMB was analyzed by linear and non-linear finite element simulation,and it was concluded that the stiffness value of WMB under the linear analysis hardly changed with the change of compression,which was a certain value;the stiffness value under the nonlinear analysis increases with the increase of the compression;the average value of the stiffness simulation under the linear analysis and the nonlinear analysis is not much different.The article analyzes the influence of several working conditions of WMB in actual working condition on its maximum stress,maximum strain,maximum deformation and fatigue life.The influence of compression and medium pressure on the maximum stress,maximum strain,maximum deformation and fatigue life of WMB is analyzed,and the most vulnerable position of WMB is obtained,compare the results of linear and non-linear finite element analysis and draw conclusions;set material properties that change with temperature,conduct thermo-solid coupling,and analyze the influence of temperature changes on WMB,the results show that under 700℃,the influence of temperature on the maximum stress,maximum strain and fatigue life of WMB shows an irregular trend,but the overall effect is small,which proves the excellent mechanical properties of Inconel-718.Summarizing the above finite element simulation results,it is concluded that among the three specifications of WMB,the95 double specifications have the best mechanical properties,the 8197 specifications are in the middle,and the 95 single specifications are the worst.Design and carry out the axial stiffness test of WMB,and compare the finite element simulation results.It shows that the axial stiffness test results are closer to the trend of the nonlinear finite element simulation results,and the error between the simulation results and the test results is basically Within 10%,it proves the correctness of using ansys workbench for the nonlinear analysis of the mechanical properties of WMB. |
