| 1. |
- Liu, Yang, et al.
(författare)
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Investigation on residual stress evolution in nickel-based alloy affected by multiple cutting operations
- 2021
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Ingår i: Journal of Manufacturing Processes. - : Elsevier BV. - 1526-6125. ; 68, s. 818-833
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Tidskriftsartikel (refereegranskat)abstract
- Machining-induced residual stresses in a part can significantly influence its performance and service time. It is common that the final surface of the part is produced after multiple cuts in the machining process. In multiple cuts, the previous cuts could often generate accumulated strain/stress and temperature on the part surface. These accumulated strain/stress and temperature will be brought to the subsequent cut or final cut and continuously affect the cutting forces, process temperatures, deformation zones, etc. in subsequent cut, and eventually affect the final residual stresses on the part. This paper reports on a joint experimental and numerical investigation to explore the influence of previous cuts on surface residual stresses with consideration of cutting parameters, cutting procedure, and tool geometries in multiple cut of Inconel 718 alloy. Coupled Eulerian and Lagrangian (CEL) formulation is used in a two/three-cuts numerical model. The loading cycles of the selected material nodes are characterised based on isotropic constitutive model (Johnson-Cook model) to analyse the underlying mechanism of residual stress evolution during cutting sequences. The results show that accumulated stress/strain induced by previous cuts lead to a more curled chip morphology, a slight decrease in cutting force and a slight increase in feed force in the subsequent cut. An increased magnitude and depth of compressive residual stresses in the finished workpiece are generated owing to the influence of previous cuts, and this is more obvious when the previous cut is implemented at a larger uncut chip thickness, using a more negative rake angle or a larger edge radius tool. The residual stress level might be controlled by optimizing the previous cuts to get the desired surface integrity.
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| 2. |
- Liu, Yang, et al.
(författare)
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Numerical and experimental investigation of tool geometry effect on residual stresses in orthogonal machining of Inconel 718
- 2021
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Ingår i: Simulation Modelling Practice and Theory. - : Elsevier BV. - 1569-190X. ; 106
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Tidskriftsartikel (refereegranskat)abstract
- Residual stress has become more important than ever with the increasing performance requirement of components especially for those applied in safety-critical areas. As the machining process is fundamentally correlated with the acquired component properties, it is essential to fully understand the formation mechanism of residual stresses in the cutting process and its influence on the performance of the component. This paper presents results based on numerical and experimental analysis on the effect of tool geometry on thermal-mechanical load and residual stresses in orthogonal machining Inconel718 alloy. The Coupled Eulerian-Lagrangian (CEL) method is used to simulate the effect of tool geometry on temperatures, forces, equivalent plastic strains, and residual stresses. The local normal/tangential stress is introduced to determine the degree of the tensile plastic deformation induced by the tool. It is observed that a negative rake angle and a sharp edge radius tool tend to generate more compressive stress on the machined surface than the ones generated with positive rake angle tools and/or lager edge radius. Besides, an increase in flank wear produces less magnitude of compressive stress in subsurface due to a decreased local normal stress caused by increased flank contact length.
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| 3. |
- Weng, Jian, et al.
(författare)
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An analytical method for continuously predicting mechanics and residual stress in fillet surface turning
- 2021
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Ingår i: Journal of Manufacturing Processes. - : Elsevier BV. - 1526-6125. ; 68, s. 1860-1879
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Tidskriftsartikel (refereegranskat)abstract
- A novel and effective approach for determining mechanics and residual stress when turning a component with curved surfaces is presented in this paper. This predictive approach is based on a three-dimensional analytical model to study the distributed mechanics and residual stress caused by vary cutting condition during the machining process. The variation of uncut chip area in this process can be divided into several stages based on different tool-workpiece contact and the discretization of cutting edge is conducted at an arbitrary tool position. The chip flow direction is calculated through the equilibrium of the incremental interaction forces. The cutting force can be determined by integrating the force components along the cutting edge, with each incremental force component obtained based on a fully analytical model. Distributed heat source intensity is considered to model the temperature rise at an arbitrary point in workpiece. The residual stress in curved surface machining is obtained considering the loading-unloading-relaxation procedure at the engagement of cutting edge and machined surface. Finally, Finite Element (FE) modeling and experiments are performed to validate the correctness and robustness of the analytical model proposed in this paper. The results of predicted chip flow direction, cutting force, temperature, and residual stress show good agreement with the simulated and measured results.
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| 4. |
- Xu, Dongdong, et al.
(författare)
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Investigation of the influence of tool rake angles on machining of inconel 718
- 2021
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Ingår i: Journal of Manufacturing and Materials Processing. - : MDPI AG. - 2504-4494. ; 5:3
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Tidskriftsartikel (refereegranskat)abstract
- It is essential for superalloys (e.g., Inconel 718) to obtain an anticipated surface integrity after machining, especially for safety critical areas (e.g., aerospace). As one of the main characteristics for cutting tools, the rake angle has been recognized as a key factor that can significantly influence the machining process. Although there are large research interests and outcomes in the machining of nickel-based superalloys, most of them focus on the surface integrity and macroscale temperature observation, whereas the temperature distribution in the tool rake face is not clear. Thus, it is necessary to investigate the basic role of rake angles and the tool–workpiece interaction mechanism to determine the machining condition variations and surface integrity. In the present study, both experimental and numerical methods are employed to explore the cutting force, thermal distribution, and shear angles during the process and the metallurgy characteristics of the subsurface after machining, as well as the mechanical properties. The research has emphasized the importance of rake angles on both the cutting process and machined surface integrity, and has revealed the microscale temperature distribution in the tool rake face, which is believed to have a close relationship with the tool crater wear. In addition, it is clearly presented that the surface generated with positive rake angle tools generates the minimum subsurface deformation and less strain hardening on the workpiece.
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