Research on the Uneven Deformation Law of High Temperature Alloy Large Caliber Ultra-Thin-Walled Tube Parts during Spinning

Based on the established spinning forming model of GH 4169 large caliber ultra-thin-walled tube parts, the radial stress-strain, normal stress-strain, and circumferential stress-strain distributions were analyzed through simulation methods. The uneven deformation law of GH 4169 large caliber ultra-thin-walled tube parts during spinning was obtained. The results indicate: With the progress of spinning, the radial stress is presented as tension, the normal stress is presented as compression, and the circumferential stress is presented as tension and compression. Therefore, the distribution of equivalent stress is uneven, leading to different tensile and compressive states of the triaxial principal strains in all directions, resulting in a small amount of fluctuation at the edge of the blank.


Introduction
The production of metal W sealing rings affects the airtightness of the engine, thereby affecting its performance.Because of its existence of weld, it will lead to the engine performance is not good.By spinning high-temperature alloy sheets to form large caliber ultra-thin-walled tube parts, and then obtaining a W sealing ring without welds through shearing and spinning, its sealing efficiency can be greatly improved, thereby improving the quality of aviation engines.Spinning forming is a near-net forming process.Using simple tools, products can obtain high process accuracy and good surface finish, and there are many types of products that can be applied [1].In recent years, L v et al. [2] have studied the spinning deformation characteristics of thin-walled tube parts, the inner part is a spiral inner rib.At the same time, the stress and strain of the tube wall area of the tube part are emphatically analyzed.Ling [3] mainly studied the deep drawing spinning process and quality control of GH 4169 conical tube parts.In the study, the effects of materials, blank diameter and thickness on the key parameters such as the location of instability wrinkling, the maximum tangential compressive stress and the maximum tensile stress in the generatrix direction were discussed.Li et al. [4] studied the problem of blank spinning wrinkling.By improving the design of tool path and process parameters, it is concluded that the critical forming depth of tool path contour is an accurate and effective measure to predict wrinkling.At present, a large number of studies have been carried out on the spinning forming of tube parts at home and abroad, but there are few studies on the spinning of large caliber ultra-thin-walled tube parts of GH 4169.Therefore, in this paper, the finite element simulation is used to study the uneven deformation law of high-temperature alloy large caliber ultra-thin-walled tube parts.

Establishment of Spinning Model
The spinning model based on ABAQUS/Explicit is shown in Figure 1.The height of the mandrel is 500 mm, the radius is 600 mm, and the fillet radius is 60 mm.The thickness of the blank is 0.25 mm, with a radius of 750 mm, and the material is defined as GH 4169, its mechanical parameters and properties are: density 8.2 g/ c m 3 , elastic modulus 203.1 G pa, Poisson's ratio 0.3.The radius of the roller is 140 mm, and the fillet radius is 8 mm.Two rollers present 180 degrees around the central axis, and the first spinning process is carried out simultaneously between the roller and the blank at 45°.The penalty friction setting for the interaction between the mandrel and the blank is 0.35, and the penalty friction setting for the interaction between the roller and the blank is 0.02 [5].The mandrel is bound to the blank and actively rotates, causing the blank to rotate around its axis at a constant angular velocity.Each roller is set a local coordinate system, reference point and a suitable trajectory.The blank is defined as a deformable entity.The mandrel and roller are defined as rigid bodies.

Reliability analysis of the Model
The model's reliability depends on the proportion of kinetic energy to internal energy after the initial spinning process.If this ratio is below 5%, the model can be considered reliable; otherwise, it is deemed unreliable.[6].The kinetic energy to internal energy ratio during the stable stage of spinning for large caliber ultra-thin-walled tube parts falls below 5%.Hence, the model is considered reliable.As the spinning process progresses, the equivalent stress gradually increases, and at the same time, the maximum equivalent stress often appears at the corner of the mandrel, and the uneven area also continues to expand.The distribution of equivalent strain of the blank is shown in Figure 3.As shown in the figure: As the spinning process progresses, the equivalent strain value gradually increases, reaching a maximum value of 9.8, and the strain at the corner of the mandrel remains uneven.The distribution of radial stress, normal stress, and circumferential stress in different spinning processes is shown in Figure 4.As shown in the figure: In the initial stage of spinning, radial stress and normal stress are relatively symmetrical.As the spinning progresses, the triaxial principal stress becomes more uniform.However, the radial stress at the edge of the blank is tensile stress, while the normal stress is compressive stress.For circumferential stress, both tensile and compressive stress coexist at the beginning of spinning.As the spinning progresses, there are also small fluctuations at the edge of the blank.The distribution of radial strain, normal strain, and circumferential strain in different spinning processes is shown in Figure 5.As shown in the figure: At the beginning of the spinning process, the radial strain, normal strain, and circumferential strain of the blank are all relatively small.As the spinning progresses, the strain values all increase.As the spinning progresses, there are tensile and compressive strains at the corner of the mandrel.At the edge of the blank, the radial strain is mainly tensile strain, the normal strain is mainly compressive strain, and the circumferential strain is both tensile and compressive strain.

Conclusion
1.As the spinning process progresses, the triaxial principal principal stress will increase, leading to an increase in the triaxial principal strain, and the value at the corner of the mandrel is usually larger.2. The radial stress is mainly tensile stress, the normal stress is mainly compressive stress, and the circumferential stress is mainly a combination of tensile and compressive stress.Due to the superposition of the three, the equivalent stress presents an uneven state, and at the same time, it leads to uneven stress on the blank, with a small amount of fluctuation at the edge.

2 .
a) 20% equivalent stress distribution b) 100% equivalent stress distribution Figure Equivalent stress distribution under different spinning processes The distribution of equivalent stress in the blank is shown in Figure 2. As shown in the figure: At the beginning of spinning, the stress appears serrated and unevenly distributed at the corner of the mandrel.Roller Blank Mandrel

3 .
a)20% equivalent strain distribution b)100% equivalent strain distribution Figure Equivalent strain distribution under different spinning processes

4 .
a)20% radial stress distribution b)100% radial stress distribution c)20% normal stress distribution d)100% normal stress distribution e)20% circumferential stress distribution f)100% circumferential stress distribution Figure triaxial principal stress distribution under different spinning processes

3. 4
Analysis of triaxial principal strain distribution law a)20% radial strain distribution b)100% radial strain distribution c)20% normal strain distribution d)100% normal strain distribution e)20% circumferential strain distribution f)100% circumferential strain distribution Figure 5. triaxial principal strain distribution under different spinning processes