Prediction of exit profile distortion in forward extrusion process using Riemann mapping theorem and upper bound method

Meccanica ◽  
2020 ◽  
Vol 55 (5) ◽  
pp. 1099-1118
Author(s):  
Majid Sheikhpour ◽  
Seyed Jamal Hosseinipour ◽  
Mohammad Javad Mirnia
Keyword(s):  
Upper Bound ◽  
Extrusion Process ◽  
Riemann Mapping ◽  
Upper Bound Method ◽  
Riemann Mapping Theorem ◽  
Forward Extrusion

Mechanical Solutions for Hot Forward Extrusion under Plane Strain Conditions by upper Bound Method

2008 ◽  
Vol 367 ◽  
pp. 201-208 ◽  
Author(s):  
Rosario Domingo ◽  
A.M. Camacho ◽  
E.M. Rubio Alvir ◽  
M.A. Sebastián
Keyword(s):  
Plane Strain ◽  
Upper Bound ◽  
Analytical Methods ◽  
Mechanical Parameters ◽  
Upper Bound Method ◽  
Zone Length ◽  
Forward Extrusion ◽  
Dead Metal Zone ◽  
Fractional Reduction ◽  
The Dead

This paper present a study focused on hot forward extrusion by upper bound method. In particular, hot forward extrusion of plates through square face dies under plane strain conditions. Slater defines the models used for large fractional reduction. Different models have been taken in account; they are dissimilar in relation to the dead metal zone (if covers or not the entire die face, partially or totally). Triangular rigid patterns of velocity discontinuities have been validated by analytical methods and a range of use for the selected configurations has been established. This methodology has been applied to other process with good results. Thus, the mechanical parameters analysed are fractional reduction, dead metal zone, length die and friction. Finally the calculation of the energy has been achieved by upper bound method. The results allow researching an optimisation of use of upper bound method in hot forward extrusion.

scholarly journals МОДЕЛЮВАННЯ ПРОЦЕСІВ КОМБІНОВАНОГО РАДІАЛЬНО-ПРЯМОГО ВИДАВЛЮВАННЯ СКЛАДНОПРОФІЛЬОВАНИХ ПОРОЖНИСТИХ ДЕТАЛЕЙ ІЗ ВИКОРИСТАННЯМ МЕТОДУ КІНЕМАТИЧНИХ МОДУЛІВ

2021 ◽  
Vol 146 (3) ◽  
pp. 69-78
Author(s):  
Н. С. Грудкіна
Keyword(s):  
Upper Bound ◽  
Defect Formation ◽  
Metal Flow ◽  
Relative Deformation ◽  
Complex Profile ◽  
Upper Bound Method ◽  
Factors Affecting ◽  
Forward Extrusion ◽  
Power Mode ◽  
Mathematical Relationships

Expanding the capabilities of the kinematic modules method to determine the value of the relative deformation pressure and shaping of a semi-finished product in the processes of combined radial-forward extrusion such as hollow parts with a complex profile. Obtaining calculated dependencies that will allow predicting compliance with the required dimensions of the part and assessing the possibility of defect formation. Upper bound method based on the method of kinematic modules is defined investigation of the main factors, affecting the power mode of deformation and features in the shaping of a semi-finished product in the processes of combined extrusion with several degrees of metal flow freedom Based on the upper bound method by using a kinematic module with two degrees of metal flow freedom is determined the value of the relative deformation pressure for make scheme of combined radial-forward extrusion such as hollow parts with a complex profile. The dependences of the increments in the semi-finished product that make it possible to analyze the influence of technological factors in the process of shaping and possible defect formation in the form of dimple are determined. The possibilities of the upper bound method by using kinematic modules with several degrees of metal flow freedom to assess the power mode and shaping of a semi-finished product in the processes of combined extrusion are determined. Significant influence of friction conditions and geometric parameters of the process the appearance of dimple in combined radial-forward extrusion such as hollow parts with a complex profile are considered. Mathematical relationships for calculating the value of the relative deformation pressure and increments of the semi-finished product in combined radial-forward extrusion such as hollow parts with a complex profile that will contribute to a more active introduction of combined extrusion processes in production are determined.

Upper Bound Analysis and Finite Element Simulation of Bi-Metallic Tube Backward Extrusion

2012 ◽  
Vol 445 ◽  
pp. 155-160
Author(s):  
H. Momeni-Khabisi ◽  
H. Haghighat ◽  
M.J. Momeni-Khabisi
Keyword(s):  
Finite Element ◽  
Upper Bound ◽  
Extrusion Process ◽  
Extrusion Force ◽  
Upper Bound Method ◽  
Metallic Tube ◽  
Backward Extrusion ◽  
Element Simulation ◽  
Reduction In Area ◽  
Good Agreement

In this paper, the process of bi-metallic tube backward extrusion through a conical punch, by means of upper bound method and finite element method is investigated. A cylindrical admissible velocity field is developed and by calculating the internal, shear and frictional powers, the extrusion force is estimated. The extrusion process is also simulated by using the finite element code, ABAQUS. Analysis and simulations are done for two types of bi-metallic tubes: aluminum as core, copper as sleeve (Al-Cu) and copper as core, aluminum as sleeve (Cu-Al). The extrusion force from the upper bound method is compared with the Finite Element results. This comparison shows that the upper bound predictions are in good agreement with the Finite Element results. The results also show that, the extrusion force in the case of Al-Cu tube is smaller than Cu-Al tube and in both types of bi-metallic tubes, the aluminum leaves the deformation zone sooner than the copper. Finally the effects of various extrusion parameters, such as the friction factor, reduction in area and semi-punch angle upon the extrusion force are investigated and the optimum semi-punch angle is determined.

Experimental Study of a Full Forward Extrusion Process from Metal Strip

2012 ◽  
Vol 504-506 ◽  
pp. 587-592 ◽  
Author(s):  
Marion Merklein ◽  
Tommaso Stellin ◽  
Ulf Engel
Keyword(s):  
Extrusion Process ◽  
Metal Strip ◽  
Raw Material ◽  
High Rate ◽  
Process Chain ◽  
Forward Extrusion ◽  
Bulk Forming ◽  
Material Conditions ◽  
Set Up ◽  
Tooling System

A high rate of production of complex microparts is increasingly required by fields like electronics and micromechanics. Handling is one of the main problems, limiting those forming processes of small metal components consisting of multiple forming stages. A forming chain in which a metal strip acts both as raw material and support of the workpiece through the different stages of the process, is seen as a solution that radically simplifies the positioning of microparts. Each workpiece stays connected to the strip through all the forming steps, being separated just at the end of the process chain. In this work, a tooling system for the bulk forming from copper strips has been set up and employed in a full forward extrusion process of a micro-billet. The same die, with a diameter of 1 mm, has been used with three different strip thicknesses (1, 2 and 3 mm) and three different material conditions. The use of thinner and hard-as-rolled strips has resulted in achieving a higher ratio of the billet length to strip thickness.

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