Advanced Materials Research Vols. 941-944

Abstract: Rotary swaging, which is commonly used to reduce the diameter of bars and tubes, is an open die process according to DIN 8583. There are always some physical defects in rotary swaged products. These defects, which may be on the surface or internal, are not desirable because they may produce bad surface appearance and even adversely affect the strength, service life, formability and other manufacturing characteristics of the products. In this work, some defects occurred in rotary swaged products are examined to determine the causes and to suggest the remedies.

Abstract: Rotary punching is a sheet metal blanking process which utilizes shearing tools fixed to a pair of rollers. The polyurethane pad is adopted as the die instead of rigid mold because it has the advantages of wide hardness range and high load-bear capacity. Due to the application of polyurethane pad, the surrounding region adjacent to the pierced hole will occur to plastically deform and deflect, which greatly differs from that in the conventional blanking. In this paper, the effects of blank material and thickness, polyurethane hardness, punch penetration depth on deformation behavior were mathematically analyzed and modeled, and then a series of experiments through varying process parameters were conducted to validate the relationship between process parameters and product quality. The degree of sample deflection was exactly measured by scanning electron microscope (SEM). The results show that the deformed area varies with different blank elongations and increases with increasing blank thickness for a given material. When polyurethane pad with low hardness level is employed, it results in large area deformation and quality degradation. Moreover, the deflection degree around the hole edge becomes more severe along with punch penetration, but the penetration depth along blank thickness is not in proportion to the amount of punch advancement.

Abstract: High conductive Niobium-Titanium alloy has the advantages of good corrosion resistance, high specific strength, good thermal stability, etc. The rotary forging technology of Nb-Ti alloy ingot with type prepared by vacuum smelting method was studied. The results show that coarse and homogeneous casting-microstructure becomes strip deformation microstructure after rotary forging. With the increase of deformation degree and deformation velocity, the space of strip deformation microstructure decreases and yield strength of alloy increases. Nb-Ti alloy bar after deformation is still type alloy with a thermal stability.

Abstract: Using advanced high strength steel (AHSS) instead of traditional mild steel is the development trend of automotive lightweight. Rectangular tube, as an important component of the vehicle, its forming principle and technology analysis is particularly important. Combining the practice production in this paper, the basic principles of circle-to-rectangular forming (CRF) and strip-to-rectangular forming (SRF) process are analyzed. ABAQUS software and PROFIL of roll pass-aided design software are used to analyze the characteristic of two roll forming processes in terms of residual stress, dimensional accuracy of the pre-punched holes and weldability. The study shows SRF process is more suitable for AHSS than CRF process.

Abstract: A numerical simulation was conducted to investigate the effect of the punching clearance, the thickness of sheet, and the hardness of polyurethane pad on the process of punching by finite element program ABAQUS which based on shear failure criterion and arbitrary Lagrangian-Eulerian adaptive meshing method. And the collapse height dimension and width dimension tendency of the sheet under different control parameters was analyzed after punching process according to this simulation result. The results show that the collapse height dimension and width dimension decreased with the increase of the polyurethane hardness, it means the cross section quality perspicuously has been increased; the collapse height dimension and width dimension decreased with the increasing of the sheet thickness; while the influence of the punching gap is indistinctive.

Abstract: Bi-metallic tubes (BMTs) combine performance advantages of two different tubes and are usually used in particular conditions where corrosion resistance is important. Traditionally, BMTs are manufactured by plastic processes such as extrusion, explosive welding/cladding, hydroforming and even combinations thereof. However, rotary swaging, which is commonly used to produce tubes, was seldom mentioned when preparing BMTs. In this work, Cu-Al BMTs were achieved using swaging-diffusion method (SDM). The effect of process on formability of BMTs are investigated. The experimental results indicate that with the increasing of deformation, metallurgical bonding layer, which is more desirable than mechanical bonding layer, can be achieved. And the metallurgical bonding layer will thicken to 2μm after diffusion. Besides, some failures produced in the swaging process are presented.

Abstract: Metal blanking is a widely used process in high volume production of sheet metal components. The main objective of this paper is to provide an overview of the state of the several blanking processes including conventional blanking, fineblanking and rotary blanking from both experimental research and finite element analysis. This paper also includes the blanking mechanicals.

Abstract: With deepening of roll forming technology and the proficiency of computer aided design and finite element Analysis (FEA) technology, it is widely noted that using the technology of FEA to simulate the roll forming process. In this paper, the current status of finite element simulation for roll forming process at home and abroad is summarized. And the finite element theories of deformation zone in roll forming process are analyzed. The new issues on roll forming process faced by finite element simulation, including advanced high strength steel (AHSS), multipass heterosexual cross section and coupling thermo-mechanical-metallurgical (TMM) coupling etc. are discussed. Moreover, the future trends of numerical simulation about the roll forming process are forecasted.

Abstract: It is a complex coupling of multi-physics field for metal deformed flow behavior under the condition of adhesive friction, which has been studied in this paper. In this paper, ring upsetting has been carried out with various press amounts. By comparisons of the transient displacement figure of internal & external metal particles under different press quantities, deformed flow state of metal particles is obtained, and inverse flow is found under the adhesive friction. Based on transient displacement obtained by ring upsetting, the flow orientation of the whole specimen is specifically acquired by means of piecewise cubic hermite polynomial interpolation. In the end, representation model of deformed flow behavior is put forward to illustrating and predicting the flow behavior of metal particles.

Abstract: The innovative hybrid impact hydroforming (IHF) technology is a kind of high energy forming technique which can be used for forming complex parts with small features, such as convex tables, bars etc. which are widely employed in automotive and aircraft industries. The impact hydroforming technology means the most features are formed by hydroforming and the small features are rapidly reshaped by high intensity impact energy in a very short time after the traditional hydroforming. The impact pressure rises to the peak in 10ms which belongs to dynamic loading. The present work investigates IHF using a numerical /experimental approach. Finite element simulations using MSC.Patran were carried out changing the geometrical shape of liquid hammer.. Using this shock wave loading condition we did forming experiments. During forming process, stress distribution in the blank is comparatively better as compared with traditional methods so possibility of fracture is reduced. Inertia is also an important factor which affects control quality. Therefore, the research is very useful for improving forming quality of complicated products. It will be widely applied in automotive and aircraft industries.