• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.10 s.175
• /
• pp.49-55
• /
• 2005

The objective of this study was presented with a prediction on the alignment of cementite in pearlite lamella structure of high carbon steel by means of finite-element method(FEM) simulation. Pearlite strcuture was characterized by its nano-sized microstructure feature of alternation ferrite and cementite. FEM simulations were performed based on a suitable FE model describing the boundary conditions and the material behavior. With the alignment of lamella structure in high carbon pearlite steel wire, material plastic behavior was taken into account on plastic deformation and alignment of cementite. The effects of many important parameters(reduction in area, semi-die angle, initial angle of cementite ) on wire drawing process were predicted by DEFORM-2D. As the results, the possibility of wire fracture could be considerably reduced and the productivity of final product could be more increased than before.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2007.05a
• /
• pp.250-253
• /
• 2007

It is known that fine straightness of micro-wire can be obtained by removing residual stress induced during the manufacturing processes. Generally, residual stress is removed or minimized through several drawing processes with heat treatment. In this study, the residual stress at each straightening process is calculated and monitored by finite element analyses and the main reason of stress change is investigated.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.10a
• /
• pp.231-232
• /
• 2006

• Transactions of Materials Processing
• /
• v.13 no.8
• /
• pp.710-715
• /
• 2004

The effect of microstructural features on ductility of cold drawn pearlitic steels containing 0.52 ～ 0.92 wt%C was investigated. During wire drawing, reduction of area (Rh) increased initially with the progressive realignment of randomly oriented cementite, showed a maximum peak due to the completion of the alignment of most cementite, and decreased with thinning or fragmentation of the aligned cementite. Among factors on ductility, cementite thickness was found to be the most dominant microstructural feature for Rh of drawn pearlitic wires, regardless of transformation temperature and carbon content in steels.

• Transactions of Materials Processing
• /
• v.19 no.4
• /
• pp.224-229
• /
• 2010

During the multi-pass wire drawing process, wires suffer a great amount of plastic deformation that is through the cross-section. This generates tensile residual stress at surface of drawn wires. The generated residual stress on surface is one of the problems for quality of wires so that prediction and reduction of residual stresses is important to avoid unexpected fracture. Therefore, in this study, the effect of process variables such as semi-die angle, bearing length and reduction ratio on the residual stress was evaluated through Finite Element Analysis. Based on the results of the Analysis, a prediction model was established for predicting residual stress on the surface of high carbon steel(AISI1072, AISI1082). To identify the effectiveness of the proposed model, X-ray diffraction is used to measure the residual stresses on the surface. As the result of the comparison between calculated residual stresses and measured residual stresses, the model could be used to predict residual stresses in cold drawn wire.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2004.08a
• /
• pp.27-36
• /
• 2004

Contemporary objectives for steel rod rolling processing are increasingly complex and often contrasting i.e. obtaining a desired product with optimum combination of properties such as strength, toughness and formability at lower cost. Low-alloy steel rods have been produced with several heat treatments for drawing and forging processes at room temperature. In order to reduce these heat treatments much of the researches concerning of high temperature mechanical behavior of steel rods have been conducted at wire rod mill of POSCO. In this present work, optimizations of rolling temperature and cooling rate for JS-SCM435 are performed to eliminate softening heat treatment(Low Temperature Annealing) for drawing process. The results from the optimization changed the microstructure of rods after rod rolling from Bainite with high tensile strength of 1000Mpa to Pearlite and Ferrite with appropriate strength of 750Mpa that is equivalent tensile strength after softening heat treatment.

• Journal of the Semiconductor & Display Technology
• /
• v.18 no.2
• /
• pp.23-28
• /
• 2019

Wire breakage in drawing, which is the most critical process in glass fiber manufacturing, is caused by numerous factors such as height, drawing speed, and air flow. The vibrations of the draw tower, however, is the most dominant factor to create the wire breakage. In this study, the structure of a draw tower has been analyzed through experiments and computer simulations to figure out the main reasons of the vibrations. And the design alterations were applied to the machine to identify the effects of those alterations. The result shows that design alterations of the draw tower structure can suppress the 87% of the vibrations, and further can prevent the wire breakage.

• Steel and Composite Structures
• /
• v.22 no.4
• /
• pp.745-752
• /
• 2016

An investigation has been done to study the evolution of the microstructure, mechanical and electrical properties of AlMgSi alloy destined for the transport of electric energy, in function of the deformation caused by the cold drawing process. We identified that drawing of aluminum wire causes development of a fibrous texture of type <111> and <100>. We notice also that the electrical resistivity and mechanical resistance increases with the increasing of the deformation level. Characterization methods used in this work is: The Electron Back Scattered Diffraction EBSD, X-Ray diffraction, Vickers microhardness, Tensile test, Measuring electrical resistivity, the Scanning Electron Microscope (SEM) and Energy Diffraction Spectrum (EDS).

• Journal of The Korean Association For Science Education
• /
• v.22 no.5
• /
• pp.944-956
• /
• 2002

The purpose of this study was to investigate students' conceptions of the simple electric circuit using a battery and a bulb. 19 fourth grade students from a rural elementary school in Korea participated in this study. Data on the children's understandings of electric circuit were collected through three sources; prediction tests, drawing tests and individual interviews. The prediction tests were paper and pencil tests composed of 10 problems, predicting whether bulbs in 10 simple circuit diagrams would light. For each prediction, the children were asked to provide a written explanation of their thinking. The drawing tests consisted of 6 problems. One was to draw the inside of the bulb base, and the others were to make the wire connections between a battery and a bulb in the diagrams, to light the bulb. The interviews were conducted with seven children who showed differing degrees of understanding. No student was aware of the wire connections inside the bulb base. Many students stated whether the bulb would light or not, according to the tip of the bulb contacting the positive battery terminal and an end of wire contacting the negative battery terminal. Most of them thought that the tip of the bulb should contact the positive battery terminal, so that the bulb would light. In short, students did not use a scientific conception of electric current to predict and explain the electric circuit.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.10
• /
• pp.1479-1485
• /
• 2010

In recent times, due to wire drawing of high carbon steel at a high speed to ensure a high productivity and high strength, axial residual stress are generated because of rapid increase in surface temperature. In the process, the temperatures of the wires increased because of the deformation of the wires and the friction between the die and wire. In particular, in the case of the wire drawing at a high speed, friction leads to a large temperature gradient so that considerable axial residual stress is generated on the surface. In this study, the relationship between axial residual stress and increase in the surface temperature was investigated, and a prediction model of uniform temperature was proposed. Then, a prediction model for residual stress was developed. The proposed model was verified by measuring the residual stress by X-ray diffraction on drawn wires.