• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2001.10a
• /
• pp.309-312
• /
• 2001

FEM simulating system of the cross-rolling texture formation offers a systematic and efficient way of exploring the relationship between the process variables and the state of plastic anisotropy of sheet product. Cross-rolled sheets possess higher average plastic strain ratios and lower planer anisotropy than those of the straight-rolled sheets. The employed model is a finite-element polycrystal model which each element used in FEM is assumed to be a crystal having different orientation by Takahashi. Texture development, deformation textures due to cross-rolling are predicted for face-centered cubic sheet metal. Crystal orientations are assigned on the basis of the pole figures obtained by X-ray diffraction. Development of anisotropy during cross rolling of an fcc sheet material is predicted theoretically with respected to flow stress and R-value in tensile test.

• Transactions of Materials Processing
• /
• v.11 no.8
• /
• pp.710-715
• /
• 2002

This paper describes the numerical determination of optimum blank diameter for sound material flow and high precise thread profile of a spindle screw through external thread rolling using two-three roll dies. Initial blank diameter affects the dimensional accuracy and surface finish qualities of a spindle screw in thread rolling process, therefore it is very important to determine the optimum blank diameter in thread rolling process. In order to determine the optimum blank diameter, this paper suggests the calculation method of initial bland diameter considering the real shape of tooth. The finite element code DEFORM is applied to analyze the metal flow of tooth, and these analytical results are verified by thread rolling experiment for spindle screw.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.30 no.10 s.253
• /
• pp.1328-1334
• /
• 2006

In the rolling mills for sheet metal rolling, paper rolling and etc., the impurities of roller surface have crucial effects on the surface quality of the products obtained by rolling. The Roll Cleaner is a device to remove impurities on roller surface during a rolling operation. Nip Pressure means the line pressure interacted between the roll cleaner blade and the roller surface. The nip pressure is the most important parameter which decides the performance of roll cleaner, and it depends upon several factors including the cleaner design and its blade stiffness. This study, first, analyzes the mechanism of the nip pressure generation for a roll cleaner designed commercially, which is an crucial process for effective design of roll cleaners. Second, the technique for the measurement of nip pressure is developed, which is useful to verify the performance of roll cleaners and to setup them properly at factory floor.

• Transactions of Materials Processing
• /
• v.3 no.1
• /
• pp.3-17
• /
• 1994

The semi-solid metal forming for vigorously agitated semi-solid alloys has been widely studied over the last decade. Metal forming processes are now being developed using alloys in the semi-solid state, among them are rolling, forging, extrusion, and die casting. Some of these are now employed commercially to produce a components and are also used to fabricate metal matrix composites. The semi-solid materials can be processed either directly during solidification and for this purpose mechanical stirring was demonstrated to produce a highly solidification. This paper is concerned with the influence of processing parameters on limitations of semi-solid forming.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.142-143
• /
• 2006

Recently, automotive engines have changed to the silent chain system in order to reduce noise and to improve reliability. High contact fatigue strength is needed for the sprockets of silent chain system. As a result, a high-contact-fatigue-strength P/M material was developed using the technology of surface rolling, which densifies the surface layer of sintered parts. It was established that the contact fatigue strength of the developed material was a great improvement over that of the conventionally used sintered material.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1999.08a
• /
• pp.412-422
• /
• 1999

Scale defects generated on the strip surface in a tandem finishing mill line are collected from the strip trapped among the production mills by freezing the growing scale on the strip by the melt glass coating and shutting down the line simultaneously. The samples observed of its cross sectional figure showed the process of scale defect formation where the defects are formed at the base metal surface by thicker oxidized scale during each rolling passes. The properties of the oxidized layer growth both at rolling and inter-rolling are detected down sized rolling test simulating carefully the rolling condition of the production line. The thickness of the oxidized layer at each rolling pass are simulated numerically. The critical scale thickness to avoid the defect formation is determined through the expression of mutual relation between oxidized layer thickness and the lanks of the strip called quality for the scale defects. The scale growth of scale less than the critical thickness and also to keep the bulk temperature tuning the water flow rate and cooling time appropriately. Two units of Inerstand Cooler are designed and settled among the first three stands in the production line. Two units of scale defect is counted from the recoiled strip and the results showed distinct decrease of the defects comparing to the conventionaly rolled products.

• Proceedings of the KWS Conference
• /
• 1997.05a
• /
• pp.25-26
• /
• 1997

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1998.03a
• /
• pp.80-83
• /
• 1998

• Proceedings of the KWS Conference
• /
• 1997.10a
• /
• pp.133-134
• /
• 1997

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2009.10a
• /
• pp.128-131
• /
• 2009

In this paper, three-dimensional finite element analysis of screw rolling process of a long shaft bolt is conducted by using a rigid-plastic finite element method based metal forming simulator AFDEX 3D. A whole sequence of cold forming processes of a long shaft bolt composed of forging and screw rolling processes is simulated to reveal the mechanism of screw formation. A mesh density control function is applied near the major plastic deformation region to achieve computational efficiency.