Experimental Study On The Thermal Deformation Of Large Metal Structure

The thermal deformation has great impact on the manufacturing equipment and the thermal deformation error caused by temperature can be more than 70% of the total machining error.Domestic and foreign scholars studied the thermal deformation of mechanical structures mainly by measuring the surface temperature field of the machine tool or measuring the error and established the relationship between the temperature field and the tool deformation error.However,in these studies,researches on deformation of heavy metal structures of heavy machine tools are seldom involved.Because of the complex force of heavy machine tools,many heat sources and large structure size,it is difficult to establish an accurate analytic expression between temperature field and deformation field.Therefore,in this paper,the large metal structure of heavy machine tools is taken as research object,and the relationship between heat source propagation law and thermal deformation of large metal structure under local heat source is studied experimentally to establish the distribution law of the temperature field of large metal structure and the relationship between the change law of time and the distribution law of thermal deformation in space and the change law of time the temperature propagation rule and thermal deformation law of large metal structure.Based on the theory of heat conduction,a theoretical analysis model and a differential equation of heat conduction for large metal structure are established.The finite element method is used to solve the relationship between the temperature field variation law and the thermal deformation law in the process of continuous heating and periodic heating.The spatial distribution of the thermal deformation field and the temporal variation are the same as the temperature.The distribution law of the field in space is consistent with the law of change in time.It is proposed that the variation law of the thermal deformation field of the structure can be reflected indirectly through the temperature field,and relevant experimental research is carried out.A thermal deformation test experimental platform for large metal structure is built to verify the relationship between the temperature field variation law and the thermal deformation law revealed by the simulation.In the measurement of temperature field,fiber grating sensing technology is introduced to measure the temperature of structural parts.This is because optical fiber sensing technology has the following advantages over traditional electrical sensors: one-line multi-point,anti-electromagnetic interference,small size embedded inside the structure.The experimental results show that the relationship between the law of thermal deformation field and the variation of temperature field is consistent with the simulation results during continuous heating and periodic heating.The relationship between the deformation field and the temperature field is constructed by a multivariate linear fitting method,which can be used to measure the deformation field of the specified position of the structural member.