Radial-forward Extrusion Research Articles

The development of triangular kinematic module to calculate the deformation pressure in the extrusion processes

Аliieva L. І., Levchenko V. M., Aliiev I. S., Kartamyshev D. O. The development of triangular kinematic module to calculate the deformation pressure in the extrusion processes
 The article presents the universal kinematic module developed on the basis of the energy upper bound method, designed for use in mathematical simulations of combined processes of cold forging. In particular, this module can be used for force regime simulating and tool loads analyzing at radial-forward extrusion of hollow products with blind hole of continuous workpieces to describe deformation zones during metal flow to the center and turn zones from radial flow to backward one. The kinematically possible velocity field for convex curvilinear (parabolic) triangular module and the equations of its parabolic inclined boundary are given. Analytical dependencies for power of deformation forces, friction and shear at the boundaries of the module, as well as for the reduced pressure in a parametric form are obtained. The developed curvilinear kinematic module, the use of which makes it possible to increase the efficiency of the upper bound method for studying the processes of combined extrusion, has been tested and described. It is shown that value of reduced pressure for the curvilinear turn module is most affected by the relative thickness of the flange, its radius, the thickness of the wall of the tubular workpiece, as well as friction conditions. The possibility of correct using of curvilinear triangular module for the analysis of complex schemes of processes with several zones is demonstrated. The simulation for calculation schemes of radial-forward workpiece extrusion with variable flange height was carried out. It has been determined that the developed curvilinear triangular module due to the reducing the value of the velocity jump at its boundaries, makes it possible to reduce the upper estimate of the tool loads in comparison with the variants of simulations that were previously based on rectangular modules.

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

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.

The Study of Folding Defects during the Radial-Forward Extrusion in the Enclosed Dies

The Study of Folding Defects during the Radial-Forward Extrusion in the Enclosed Dies

Retraction Note: Accumulative Radial-Forward Extrusion (ARFE) processing as a novel severe plastic deformation technique

Retraction Note: Accumulative Radial-Forward Extrusion (ARFE) processing as a novel severe plastic deformation technique

Evaluation of mechanical and metallurgical properties of AZ91 seamless tubes produced by radial-forward extrusion method

Radial forward extrusion (RFE) is a suitable method for producing large diameter seamless tubes with superior properties from smaller cylindrical billets. Material flow along the radial and forward channels causes large effective strains and consequently improved mechanical and metallurgical properties of the final tube. In this study, isothermal RFE process was applied to a commercial AZ91 magnesium alloy at 300°C, and the mechanical properties and microstructure evolution were examined. Due to severe plastic deformation at 300°C, dynamic recrystallization occurs, and equiaxed grains were formed. The grain size was reduced to ~3µm from the initial value of ~150µm. Yield and ultimate strength were increased by 3.2 and 2.6 times compared to the initial values, respectively. Though, the resulting properties from RFE are similar to those of hot extruded AZ91. Besides, elongation was increased up to 2 times after the RFE process. Microhardness was also increased to 88 Hv from the initial value of 52 HV. Good homogeneity of effective strain and microhardness in the longitudinal section was observed while force requirement is dramatically reduced compared to the conventional extrusion. The RFE process seems to be a very promising extrusion process for producing fine-grained seamless tubes.

Hydrostatic radial forward tube extrusion as a new plastic deformation method for producing seamless tubes

Hydrostatic radial forward tube extrusion (HRFTE) as a new and innovative method is developed for producing large-diameter seamless tubes from smaller hollow billets. The HRFTE process is based on hydrostatic pressure, and radial forward tube extrusion provides the possibility of producing a large-diameter tube with low hydraulic oil pressures. In this procedure, a movable punch placed inside the hollow billet plays the main role in reducing the required hydrostatic pressure. The HRFTE process was applied to pure aluminum at room temperature, and the mechanical properties, material flow behavior, and microstructural evolution were examined. Since the large effective strains were applied to the material during the process, the strength and hardness were significantly improved. Yield and ultimate strength were increased, respectively, about 2.48 and 1.86 times compared to the initial values. Microhardness was also increased to 59 Hv from the initial value of 28 HV. Good homogeneity of effective strain and microhardness in the longitudinal section was observed, but there is an inhomogeneity along the tube thickness. The HRFTE process seems to be an extrusion process with a high capability of industrialization for producing a large-diameter seamless tube with superior mechanical properties using low hydrostatic pressures.

Numerical analysis of tool geometry effect on the wear characteristics in a radial forward extrusion

The finite element analysis has been performed to investigate the tool wear characteristics in forming a central hub component with radial protrusion by a radial forward extrusion process. The main objective of this study is to investigate the influence of tool geometries on the wear characteristics of the mandrel and container surfaces. Two major process parameters such as annular gap height and mandrel diameter were adopted to examine the wear characteristics. SCM415H steel was selected as a model material in simulation by adopting the Archard’s wear model, which was verified by comparing with experimental results in the literatures. The results of present study were summarized quantitatively in terms of wear profiles on the tool surfaces such as container and mandrel in terms of wear depth, contact pressure and sliding velocity. The localized wear depth is more sensitive to the variation of annular gap height with increase in mandrel diameter.

Analysis of Deformation Behavior in Backward–Radial–Forward Extrusion Process

The forming characteristics of backward–radial–forward extrusion process were investigated by the effect of some important die design geometry parameters. Some major flow faults such as separation height and length, asymmetric ratios of height and angle are introduced and the effects of process parameters are studied on them. The workpiece material was AL1050 and the simulation work was performed by the rigid-plastic finite element method. The validity of the simulation results obtained in this study was verified by using the experimental test data in terms of forming load and material flow. There is reasonably good agreement between the simulation and the experiment. The die geometry and frictional condition have a significant influence on the material flow into the die cavities. The work presented in this paper might be used for basic data in the design of the backward–radial–forward extrusion process.

RETRACTED ARTICLE: Accumulative radial-forward extrusion (ARFE) processing as a novel severe plastic deformation technique

A novel severe plastic deformation (SPD) technique entitled accumulative radial-forward extrusion (ARFE) is introduced for producing ultra-fine grained bulk materials. This method is based on radial-forward extrusion process because of inherent capabilities for imposing extremely high plastic strains on material. ARFE was applied to AA1050 and the ability of this process in significant grain refinement is determined even after single cycle. Transmission electron microscopy (TEM) examination showed ultra-fine grains (UFGs) with the average grain size of 450 nm after one cycle of ARFE. Furthermore, micro-hardness distribution through the part’s section indicates the hardness increase to ∼52 Hv from the initial value of ∼28 Hv after one cycle of ARFE. In order to further investigate of the accumulated strains, ARFE process was also numerically modelled by finite element method.

Numerical Studies of Some Important Design Factors in Radial-Forward Extrusion Process

In this study, the forming characteristics of radial-forward extrusion are investigated by the effect of some important die design geometry parameters such as gap height, annular gap width, mandrel corner radius, and die corner radius on forming load variations. The workpiece material was AA6063 aluminum and the simulation work was performed by the rigid-plastic finite element method. The validity of the simulation results obtained in this study was verified by using the experimental data reported in the literature. There is reasonably good agreement between the simulation and the experiment. The simulation results show the effectiveness of the above-mentioned parameters on forming load. Based on the simulation results, the annular gap width has the greatest effect on the forming load in the forward extrusion stage. Furthermore, the forming load and maximum load decrease as the gap height increases. However, the mandrel radius and the deflection radius have a slight influence on the forming load in the punch and mandrel. The work presented in this article might be used for basic data in the design of the radial-forward extrusion process. In this article the DEFORM-2D software (Scientific Forming Technologies Corporation, Columbus, OH) was used for numerical study.

An analytical approach for radial-forward extrusion process

An analytical approach is used to obtain the extrusion pressure and the strain imposed through radial-forward extrusion. For deformation analysis, the deformation volume is divided into three different regions. By considering a cylindrical coordinates, the components of the velocity field and strain rates are obtained. The effective strain achieved in each deformation region is obtained by multiplying the effective strain rates to the deformation time determined for each region. The total strain obtained from these results is large and comparable to the strain achieved by severe plastic deformation methods. Based on the upper-bound theory, an analytical equation is derived for extrusion pressure by determining the internal power and the power dissipated on all frictional and velocity discontinuity surfaces. The validity of the theoretical results is confirmed by the experiments in term of the hardness measurements and the extrusion force.

An Analysis on the Forming Characteristics of AA 6063 Aluminium Alloy in Radial-Forward Extrusion Process

In this paper, the forming process of a central hub by radial-forward extrusion has been analyzed by the rigid-plastic finite element method. In this process, the material flows in radial direction and then deflects 90 degrees into the same direction as that of punch movement. Radial extrusion is used to produce parts that generally feature a central hub with radial protrusions. Design factors such as mandrel diameter, punch nose radius, deflection corner radius, gap width in annular direction, and frictional conditions are applied to the present study by simulation. AA 6063 aluminum alloy is selected as a model material for analysis in the present study. The influence of these design factors on the force requirement during the forming operation and the pressure exerted on the tooling such as the punch and mandrel is investigated and the simulation results are quantitatively summarized in terms of pressure distribution, force-stroke relationships, and maximum force requirement, respectively. The main goal of this study is to investigate the effect of those process parameters on the deformation pattern in radial-forward extrusion process, especially the effect of deflection corner radius. It has been concluded from the simulation results that a) the frictional condition between workpiece and tool does not affect the punch load very much, but the load supported by mandrel is more or less significantly influenced by the frictional condition compared to that of punch, b) the deflection corner radius turns out to be a major process parameter in terms of maximum force requirement, and c) a similar trend is found in the punch and mandrel forces during the radial extrusion process.

The Forming Characteristics of Simultaneous Radial-Forward Extrusion Processes

Numerical simulations are applied to investigate the simultaneous radial-forward extrusion process in a combined extrusion such as subsequent radial-forward extrusion after radial extrusion. Design factors for the process such as gap height, deflection angle into annular gap and frictional condition are employed in the analysis. The analysis is focused to see the influence of design factors on the maximum force requirement for the forming process. One of the selected simulation results is compared with the experiments in terms of load-stroke relationships. The pressure distributions exerted on the die-wall interfaces are also investigated to reveal if the tooling system is safe, especially the die set. The plastic stress-strain relationship is derived analytically from the material constants used in elastic deformation analysis. It is revealed from the simulation results that the influence of the deflection angle on the maximum force requirement for the process is greatest among design parameters. AA 6063 alloy is selected as a model material for the analyses in this study.

레이디얼-전방압출 공정의 성형특성에 관한 연구

This study is concerned with the analysis of the forming characteristics of radial-forward extrusion. Angle between radial and forward extrusion, gap height, and friction factor are considered as important design factors to affect forming characteristics in radial-forward extrusion. The rigid-plastic finite element method is adopted to analyze the effects of design factors on forming loads. The incremental rates of loads are nearly constant except the deformation zone from radial to forward extrusion. The smaller angle induces lesser force increment, therefore forming load increases as the angle increases. Maximum load also increases as gap-height decreases and friction factor increases.

The forming characteristics of radial–forward extrusion

In this paper, the forming of a central hub by radial–forward extrusion is analyzed quantitatively by the rigid–plastic finite element method. Design factors such as mandrel diameter, die corner radius and friction factor are applied in the simulation. The influence of these design factors on the maximum load during the forming operation and the pressure exerted on the tooling such as the punch and the mandrel is investigated and summarized in terms of the maximum forming force. The simulation results are compared with experimental data from a reference to verify the usefulness of the simulation. Based on the simulation results, it is concluded that the maximum forming load increases as the tube diameter and/or die corner radius increase. Furthermore, the mandrel diameter among the design factors has the greatest effect on the forming load during the radial–forward extrusion process. However, the die corner radius has a slight influence on the punch load as is easily expected. The work presented in this paper might be used for basic data in the design of the radial–forward extrusion process.