• Structural Engineering and Mechanics
• /
• v.49 no.5
• /
• pp.645-660
• /
• 2014

This paper presents the design and project of an innovative concept for a Single Point Incremental Forming (SPIF) Machine. Nowadays, equipment currently available for conducting SPIF result mostly from the adaptation of conventional CNC machine tools that results in a limited range of applications in terms of materials and geometries. There is also a limited market supply of equipment dedicated to Incremental Sheet Forming (ISF), that are costly considering low batches, making it unattractive for industry. Other factors impairing a quicker spread of SPIF are large forming times and poor geometrical accuracy of parts. The following sections will depict the development of a new equipment, designed to overcome some of the limitations of machines currently used, allowing the development of a sounding basis for further studies on the particular features of this process. The equipment here described possesses six-degrees-of freedom for the tool, for the sake of improved flexibility in terms of achievable tool-paths and an extra stiffness provided by a parallel kinematics scheme. A brief state of the art about the existing SPIF machines is provided to support the project's guidelines.

• Design & Manufacturing
• /
• v.7 no.1
• /
• pp.11-18
• /
• 2013

This paper presents the plastic inhomogeneous deformation behavior of bimetal composite rods during the axisymmetric and steady-state extrusion process through a conical die. The rigid-plastic FE model considering frictional contact problem was used to analyze the co-extrusion process with material combinations of Cu/Al. Different cases of initial geometry shape for composite material were simulated under different conditions of co-extrusion process, which includes the interference and frictional conditions. The main design parameters influencing on deformation pattern are diameter ratio of the composite components and semi-die angle. Efforts are focused on the deformation patterns, velocity gradient, predicted forming load and the end distance through the various simulations. Simulation results indicate that there is an obvious difference of forming pattern with various diameter ratio and semi-die angle. The analysis in this paper is concentrated on the evaluation of the design parameters on the deformation pattern of composite rod.

• Journal of the Korean Society for Precision Engineering
• /
• v.18 no.9
• /
• pp.186-191
• /
• 2001

Spinning process is a chipless metal forming method for axi-symmetric parts, which is more economical, efficient and versatile method for producing parts than the other sheet metal forming process such as stamping or deep drawing. In this study, a fundamental experiment was conducted to improve productivity with process parameters such as tool path, angle of roller holder($\alpha$), feed rate($\gamma$) and corner radius of forming roller(Rr). These factors were selected as variables in the experiment because they were most likely expected to hale an effect on spring back. The empirical results were analyzed to know how much spring back was affected by these factors. And also thickness and diameter distribution of a multistage cup obtained by spinning process were observed and compared with those of a commercial product produced by conventional deep drawing.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1995.03a
• /
• pp.196-202
• /
• 1995

Drawbead formulation is the first process together with a binder wrap process in a sheet metal forming process. The purpose of a drawbead is to control the flow of the metal into the die in panel press forming. To simulate the drawbead formation process, an elasto-plastic finite element formulation is derived from the equilibrium equation an drelated boundary conditions considering the proper contact conditons. The developed finite element program is applied to drawbead formation in the plane strain condition. The simulation of drawbead formation produces the distribution fo stress and strain along the bead and the resultant elongation of the sheet in the cavity region with respect to various cavity dimensions of the sheet as well as the punch force of a drawbead and the amount of draw-in with respect to the stroke fo a drawbead. The numerical resutls provides the fundamental information as a boundary condition to analyze the complex binder wrap phenomena and panel press forming in simple way.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2006.06a
• /
• pp.81-85
• /
• 2006

The characteristic of sheet metal process is the few loss of material during process, the short processing time and the excellent price and strength. The sheet metal process with above characteristic is common used in industrial field, but in order to analysis irregular field problems the reliable and economical analysis method is demanded. Finite element method is very effective method to simulate the forming processes with good prediction of the deformation behaviour. Among Finite element method, The static-implicit finite element method is applied effectively to analyze real-size auto-body panel stamping processes, which include the forming stage. In this paper, it was focussed on the drawability factors on auto-body panel stamping by AUTOFORM with using tool planing alloy to reduce law price as well as high precision from Design Optimization of die. According to this study, the results of simulation will give engineers good information to access the Design Optimization of die.

• Transactions of Materials Processing
• /
• v.18 no.1
• /
• pp.26-38
• /
• 2009

It was reported that the semi-solid forming process has many advantages over the conventional forming process, such as a long die life, good mechanical properties and energy savings. It is very important, however, to control liquid segregation to gain mechanical property improvement of materials. During forming process, rheology material has complex characteristics, thixotropic behavior. Also, difference of velocity between solid and liquid in the semi-solid state material makes a liquid segregation and specific stress variation. Therefore, it is difficult for a numerical simulation of the rheology process to be performed. General plastic or fluid dynamic analysis is not suitable for the behavior of rheology material. The behavior and stress of solid particle in the rheology material during forging process is affected by viscosity, temperature and solid fraction. In this study, compression experiments of aluminum alloy were performed under each other tool shape which is rectangle shape(square array), rectangle shape(hexagonal array), and free shape tool. In addition, the dynamics behavior compare with Okano equation to power law model which is viscosity equation.

• Transactions of Materials Processing
• /
• v.32 no.5
• /
• pp.247-254
• /
• 2023

This study conducted the wear tests on bending punches coated with PVD CrN and examined the surface quality of the product formed by each punch in the forming of uncoated TRIP1180 sheets. The study quantitatively estimated the surface quality of the product by measuring the roughness and imaging the product surface. The correlation between the punch wear depth and the product surface roughness was quantitatively analyzed. The results showed that before failure occurs, the product roughness was comparable with that of the as-received, and the product surface was smooth without scratches and defects. However, after failure, the punch wear is caused by fretting wear mechanism, and a punch whose coating is not completely peeled plows the product surface, resulting in severe scratches with grooves and ridges on the product surface. Severe wear on the punch surface caused by fretting wear can rapidly degrade the product surface quality as it is directly affected by the punch surface condition, and the product surface quality accurately reflects the punch wear condition.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2001.10a
• /
• pp.89-92
• /
• 2001

A rigid-viscoplastic finite element code for superplastic forming processes has been developed The material is assumed to be isotropic and a modified Coulomb friction law is adopted to explain contact between tool and sheet. This code uses the triangular element based on the membrane approximation and a hierarchical contact searching method is implemented The optimum pressure-time relationships for target strain rate are calculated by several pressure control algorithms. By the analysis, optimum pressure-time curves and deformation behavior are predicted.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2002.04a
• /
• pp.579-584
• /
• 2002

In press forming of sheet metals, the material sheet is usually subjected to very large plastic strain under in-plane stressing. Moreover, the sheet also very often is subjected to out-of-plane compressive force between tools such as the upper and lower dies, the blank holder and the die, and so forth. In this paper, it is clearly demonstrated theoretically that out-of-plane stress may notably raise the forming limit strain and thus it cm be effectively utilized to avoid earlier fracture of the sheet in press forming.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.4
• /
• pp.38-47
• /
• 2000

Recently, finite element method has been used as an effective tool in the design process of sheet metal forming. In the present study, an implicit method and an explicit method have been developed for 2D analysis and 3D analysis, respectively, and applied to several processes including plane strain draw bending and TWB sqaure cup drawing. Also, commercial codes are used for geometrically complex problems, such as tube hydroforming, "L" cup deep drawing and side frame forming. In this paper, basic formulations used in the methods are introduced and results obtained from the applications are discussed.discussed.