Numerical Simulation Of Rolling Process Of Large-Scale Profiled Ring Parts Research

As a basic parts of heavy equipment,large ring parts are widely used in wind power,shipbuilding,aviation and other industrial fields.Its high quality production is one of the important symbols of the national industrial level.Ring rolling is generally adopted in the manufacture of large ring parts,that is,the wall thickness of the ring parts is thinned and the diameter is enlarged by the rotation and feed of the roll on the rolling equipment.Rolled ring parts have the advantages of good quality,high performance and low in cost.However,with the rapid progress of new energy and industrialization,the demand for large ring parts with complex section is increasing,and the forming quality and performance of the ring parts are put forward higher requirements.But at present,large shaped ring parts face problems and difficulties such as unstable rolling,complex material flow,low coordination between ring parts and rolls and process parameters,which lead to unsatisfactory product forming quality.Therefore,it is necessary to study the rolling process control and stability of large profiled rings,and put forward a new technology method of high quality forming of profiled rings,to provide theoretical and technical support for the large-scale ring production at a high level in China.In this paper,as-cast Q345E steel is used as the research object,and the thermal simulation experimental method is used to conduct compression deformation experiments at different temperatures and strain rates,so that the obtained stress-strain data can be used to simulate the forming of shaped ring parts by using the finite element numerical simulation software Simufact.With the forming quality as the target,two types of blanks and six groups of different rolling methods are designed for the large inner step ring parts to study and analyze the metal flow law of different rolling methods.A new step-by-step rolling process using rectangular blanks to gradually produce axial wall thickness difference is proposed,and the influence of different process parameters on the forming quality of ring parts is investigated.It provides references for the actual production requirements and also lays the foundation for the development of flexible ring rolling technology and new rolling process.The main conclusions are as follows:（1）The stress-strain curves of as-cast Q345E steel are obtained,and the constitutive mathematical model based on the peak stress and strain compensation method is established.When the deformation temperature is higher than 1100°C,the curves all show dynamic recrystallization characteristics,where the effect of temperature change on the peak stress is greater than the peak strain.Activation energy Q=446812.721J/mol,hardening index n=5.64.The safe range of forging parameters is 1100～1250℃and strain rate of 0.1～1s^-1.（2）Two kinds of blank and six different rolling modes are designed based on the rolling of large inner step ring parts.In the rectangular blank rolling mode,a large amount of axial metal flow is needed,which leads to the defect of unfilling.When the length of blank step is equal to the length of forging step,butterfly shape and ellipse defects appear.The blank step length is longer than the forging step length,and the forming effect is good in the non-axial flow mode,which requires large blank wall thickness and is difficult to produce.When the blank step length is less than the forging step length,the forming effect is good and the blank wall thickness is small.（3）For large inner step ring forming,a new step rolling method is proposed for rectangular blanks to gradually produce axial wall thickness difference.The main process parameters of the step rolling process are:drive roll linear speed 1m/s;core roll feed speed 0.3 mm/s;ring initial rolling temperature 1250℃.In the second rolling step,the medium effect variation rule is that the strain is higher at the edge of the ring with large holes and the largest at the corner of the inner surface,and the strain at the middle of the ring with small holes and the top of the inner surface is the smallest;the temperature distribution rule is that the temperature at the middle of the ring is the highest,the temperature at the edge is lower and the corner of the inner surface is the lowest,and the temperature from the middle to the surrounding surface shows a gradient distribution from high to low.The radial and axial rolling forces and rolling moments are increasing with rolling,and the axial rolling force and rolling moment are smaller than the radial rolling force and rolling moment,while the rolling force and rolling moment have obvious fluctuations.（4）The effects of different process parameters on rolling forming were studied,and it was found that when the initial temperature of the ring,the feed speed of the core roll and the diameter of the core roll increased,the distribution of the rolling equivalent strain was more uniform;The uniformity of rolling temperature distribution decreases with the increase of initial ring temperature and core roll diameter,but the uniformity of rolling temperature distribution increases with the increase of core roll diameter.The average rolling force,maximum rolling force and average rolling moment decrease with the increase of initial ring temperature and core roll feed rate.However,the average rolling force,maximum rolling force and average rolling moment increase with the increase of core roll diameter.