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Feasibility studies on manufacturing tailored blanks by rolling partially stacked blanks
한상욱,황태우,오일영,문영훈 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.4
Tailored blanks with different blank thicknesses are semi-finished parts that can be used to produce lightweight vehicle parts. This study investigates a manufacturing process that can produce tailored blanks by rolling partially stacked blanks. The process was experimentally and numerically investigated using various processing conditions. To characterize the process, the deformation behaviors of upper and lower blanks were analyzed and quantified. The dimensional variations at the top end and the transition zones were analyzed based on the cross-sectional thickness profiles of formed blanks. The results show that the proposed process is feasible for the production of tailored rolled blanks that have both straight edges with a concave transition zone and convex edges with a straight transition zone.
Han, Sangwook,Hwang, Taewoo,Oh, Ilyeong,Choi, Moonseok,Moon, Young Hoon Elsevier 2018 Journal of materials processing technology Vol.256 No.-
<P>A tailor-rolled blank is a semi-finished part that can be used to produce stamping parts with continuous thickness variations. This study investigates a cold manufacturing process to fabricate a TRB with variable thickness variations in both the longitudinal and latitudinal directions. The effect of the rolling process on the characteristics of the transition zone and the deformation behaviors of the blanks were investigated using various processing conditions. The dimensional variations at the transition zones were analyzed based on the cross-sectional thickness profiles of the formed blanks. The results show that manufacturing such a TRB requires an extra process to reduce dimensional instabilities caused by superimposed transition zones in both directions. To manufacture sound blanks with acceptable dimensions, this study proposes a trial method that uses blanks with circular and square holes instead of solid blank.</P>
박현경(Hyun-kyung Park),정지원(Ji-Won Jeong),이경민(Gyung-Min Lee) 한국산학기술학회 2018 한국산학기술학회논문지 Vol.19 No.5
최근에 안전기준과 환경규제 강화의 증대로 인해, 차체의 경량화에 대한 연구가 지속적으로 증가하고 있다. 고강도강의 응용은 가장 보편화 된 차체 경량화의 효과적인 방법 중에 하나이다. TWB(Tailor Welded Blank)는 다양한 두께와 용접을 사용하여 부분적인 강도와 경량화를 만족시키는 주요한 공법으로 활용되고 있다. 그러나 추가적인 용접공정으로 인해 판재간의 용접성이 중요하고 용접부에 대한 품질관리가 중요하다. 이점을 개선하기 위해, TRB(Tailor Rollded Blank)공법이 제안되었다. TRB는 롤러 압력을 조절하여 판재의 두께를 다르게 하고, 용접을 사용하는 TWB 공법보다 추가적인 용접공정이 없기 때문에 생산 비용적인 측면에서 훨씬 더 효율적이다. 본 연구에서는 Blank의 압연 영향을 조사하기 위해 스탬핑용 고강도강 TRB 판재의 성형성을 분석하였다. 성형성을 분석하기 위해, TRB 판재에서 0.8 mm, 1 mm의 두께를 갖는 부분을 채취 하여 시험하였다. 시편에 새겨진 그리드마킹의 변형도를 분석하여 변형률을 조사하였고, 0.8 mm와 1.0 mm의 두께를 갖는 TRB 시편으로 Erichsen 시험을 한 후에 FE분석을 활용하여 성형성과 고유진동수를 비교하였다. Recently, research on lightweight automobiles is increasing continuously to respond to the high safety standards and environmental regulations. The application of high strength steel is one of the effective methods for developing lightweight car bodies. A TWB (Tailor Welded Blank) is major method that allows partial high strength with light weighting using a multi-thickness and multi-material welded blank. On the other hand, additional welding process is required to prepare the blank and quality control for the welding process also required. To secure this point, the TRB (Tailor Rolled Blank) method was suggested. In the TRB method, the thickness of sheet is controlled by the rolling presses and the production efficiency is much higher than welding in TWB methods. In this study, the formability of high strength TRB steel plate was analyzed to examine the rolling effect of the blank. The formability of the specimen was tested using 0.8 and 1 mm thick steel sheets for the TRB plate. The strain was analyzed by the digital image sensing of grid markings on the specimen and the forming limit diagram was calculated. An Erichsen test for the 0.8 and 1 mm thick TRB specimens was carried out and the formability was investigated by comparing with FE analysis.
E. Shafiei,K. Dehghani,F. Ostovan,Meysam Toozandehjani 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.5
In this study, anisotropic elastic and plastic mechanical properties of a tailor rolled blank (TRB) with thickness ratio of0.52 (1 mm/1.9 mm), have been fully studied. To gain a deeper insight into anisotropic mechanical behavior of the studiedTRB, continuous changes in microstructure and crystallographic texture of a dual phase steel caused by variable gaugerolling (VGR) were investigated on several points (on RD–ND plane) along longitudinal direction with the aid of EBSDobservations. Analysis of grain boundary (GB) maps revealed that ferrite grain refinement is occurred during VGR so thatthe average ferrite grain size decreases from 4.1 μm for the thicker side to 2.2 μm for the thinner side. Furthermore, it wasfound out that substructure density is more intense within smaller ferrite grains. Evaluation of inverse pole figures as well asorientation distribution function maps showed that texture of thicker side comprises {001}⟨110⟩ and {112}⟨110⟩ componentsalong -fiber. In addition, it was revealed that orientations of {111}⟨110⟩ and {111}⟨112⟩ along -fiber strengthen alongVGR direction by further increase in thickness reduction near thinner side. Accordingly, unprecedented gradual changes inmechanical properties with respect to these changes in microstructure and texture, were obtained. Finally, the correlationbetween in-plane anisotropic mechanical properties [Young’s modulus (E), yield stress (YS), ultimate tensile stress (UTS)and total elongation] of the studied tailor rolled blank with microstructure and deformation texture was interpreted.