• Design & Manufacturing
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• 제15권1호
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• pp.21-25
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• 2021

When the product is removed from the mold after molding during the sheet metal molding process, elastic recovery causes a springback phenomenon. Much research has been done to minimize this phenomenon. In this study, V-bending experiments were conducted using galvanized steel sheets, stainless steel, and aluminum sheet materials, using a total of nine types of thin sheet materials of 1.0t, 1.5t, and 2.0t, respectively. Molding analysis and experimental data were compared and analyzed. In the case of galvanized steel sheets, it was considered that the springback phenomenon occurs more frequently in molding analysis than in experiments. It was considered that the springback phenomenon occurs greatly in the experiment, not the interpretation of the molding of the stainless steel plate and the aluminum plate. It was considered that the springback occurrence tendency of the molding analysis and the experiment was the same, and the springback occurrence error rate of the molding analysis and the experimental result was about 4.0%.

• 대한기계학회논문집A
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• 제35권7호
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• pp.827-833
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• 2011

본 논문에서는 상용 유한 요소 해석 프로그램인 SAMCEF 를 이용하여 고속 철도 차량의 집전성능을 예측할 수 있는 해석 모델을 개발하였다. 3 자유도 스프링-댐퍼-질량의 판토그래프 모델을 생성하였고, 실제 시스템과의 리셉턴스를 비교함으로써 신뢰성을 검증하였다. UIC 799 OR 기준에서 제시한 가선계의 이론적 파동전파 속도와 가선계 유한 요소 해석 모델에서 측정한 파동 전파 속도를 비교 하였다. 드로퍼의 길이를 조절하여 전차선의 중력에 의한 초기 처짐 현상을 구현하였다. 가선계와 판토그래프를 접촉 요소를 이용하여 연성하였으며, 판토그래프가 300 km/h 및 370 km/h 로 주행할 때의 접촉력 변화를 도출하였다. 접촉력의 평균, 표준편차, 최대 및 최소값 등을 분석함으로써 본 논문에서 제시한 해석모델의 유효성을 검증하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.285-288
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• 2007

The use of commercial finite element analysis software to perform the entire process analysis and springback analysis has increased fast for last decade. Pamstamp2G is one of commercial software to be used widely in the world but it has still not been perfected in the springback prediction accuracy. We must select the combination of input parameters for the highest springback prediction accuracy in Pamstamp2G because springback prediction accuracy is sensitive to input parameters. Then we study the affect of input parameters to use member part for acquiring high springback prediction accuracy in Pamstamp2G. First, we choose important four parameters which are adaptive mesh level at drawing stage and cam flange stage, Gauss integration point number through the thickness and cam offset on basis of experiment. Second, we make a orthogonal array table L82[(7)] which is consist of 8 cases to be combined 4 input parameters, compare to tryout result and select main factors after analyzing affect factors of input parameters by Taguchi's method in 6 sigma. Third, we simulate after changing more detail the conditions of parameters to have big affect. At last, we find the best combination of input parameters for the highest springback prediction accuracy in Pamstamp2G. The results of the study provide the selection of input parameters to Pamstamp2G users who want to Increase the springback prediction accuracy.

• Design & Manufacturing
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• 제12권2호
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• pp.34-39
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• 2018

The biggest topics in the automobile industry are light weightening and fuel efficiency improvement. There's a lot of research going on. It is focused on light weight materials. Light weight material is seen as the best way to reduce fuel consumption and to solve the problem of environmental pollution and resource depletion. For the light weight materials, new materials such as aluminum, magnesium, and carbon-hardening materials can be found. Research on the joining techniques of dual materials, improvement of material properties by improving the method of manufacture of existing materials, and studies on ultra-high strength steel sheets are expected to take up the most weight in lightweight materials. As the strength of the ultra-high strength steel sheets increases during forming, it is difficult to obtain dimensional precision due to the increase in elastic restoring force compared to mild or high strength steel sheets. Spring back is known to be affected by a number of factors due to poor plastic molding, and can be divided into the effects of the material spraying and the process. The study on the plasticitic variables were studied as plasticitic factors that can be controlled by a part company. Tensile testing of ultra-high strength materials was conducted to derive properties for plasticitic analysis and to analyze spring back with two factors controlling the height of the bead and blank holding force by adding tensile force and controlling the flow rate.

• 소성∙가공
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• 제29권4호
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• pp.203-210
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• 2020

In this study, formability and springback behavior of 1.5 GPa grade ultra-high strength steel (UHSS) sheet were predicted through the finite element simulation, and structural stability of the forming dies was verified by the coupled forming-structural analysis. Uniaxial tension and uniaxial tension-compression tests were performed to obtain experimental data for modeling the springback properties of the sheet material. The springback values predicted by simulation were compared with those from actual measurements. The results calculated from the kinematic hardening model were found to be much more accurate than those from the isotropic hardening model. Deformation of the forming die and springback of the product were calculated by the coupled forming-structural analysis. The higher the strength of the die material, the smaller the surface displacement of the die and the springback of the product. The internal stresses of the dies made of three materials, FC300, FCD550 and STD11 were compared with the yield stress of each material. The results provided a basis for determining the most suitable material for each part of the die set. As a result, simulation techniques have been established for predicting formability and springback in the UHSS sheet forming process.

• 한국정밀공학회지
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• 제26권8호
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• pp.96-103
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• 2009

The roll forming process is commonly used for the conventional 'Fe' metal products such as a furniture drawer guide or an up-down slide guide. Recently its applications are variously expanded to the sanitary facilities or electronic devices. It is essentially required the cleanness for the high technology application and any corrosion or rust are not allowed. Therefore, in those applications the stainless steel materials are strongly demanded as the substitution of 'Fe' steel. However the mechanical properties of stainless steel are not suitable for forming process compared with those of 'Fe' steel. Up to now, the conventional F.E.M.(Finite Element Method) has been used to analyze and design the roll forming process. The purpose of this research is to obtain the proper production process and the shape of rolls to manufacture the high precision slide rails made of stainless steel material. The commercial program, SHARPE-RF, is used to analyze the entire roll forming process. The results show that the rolling process and the roll design by F.E.M. are useful from the good agreement between the shapes of products estimated by F.E.M. and those of the actual products.

• Journal of Advanced Marine Engineering and Technology
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• 제37권1호
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• pp.66-71
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• 2013

산업현장에서 널리 사용되고 있는 연질용 벤딩파이프는 벤딩 후 외관의 주름이나 스프링 백, 관이 얇아지는 현상 등이 자주 발생하여 크랙이나 파이프 파공 등의 문제가 대두되고 있지만 이를 완벽히 해결할 수 있는 벤딩기계는 아직 전무한 실정이다. 따라서 본 연구에서는 고품질 정밀형 연질재료 전용 벤딩기계의 개발을 위한 기초연구로서 벤딩툴인 맨드릴을 자체 설계제작하고 그 성능을 검증한다. 또한 벤딩 시 관이 얇아지는 현상에 대해 두께 감소율과 손상정도 등을 시뮬레이션으로 분석하고 그 해결방법을 제시하고자 한다.

• 한국자동차공학회논문집
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• 제23권6호
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• pp.642-649
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• 2015

Resistance Spot Welding (RSW) is the method for joining two overlapped base materials when high pressure and current is applied from electrodes. Due to the safety problem such high pressure and voltage, automation should be early adopted. In this paper, the spot welding is developed as a computational model of wheel house from GM Korea and the welding condition such as weld sequence is considered. The computational analysis is preceded as a static and elasto-plastic procedure and used thermal expansion coefficient represents a dependency of spot volume between two panels. In case of welding sequence, the efficiency which depends on the distance between current spot point and the other is calculated in several cases.

• 한국산학기술학회논문지
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• 제12권3호
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• pp.1091-1097
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• 2011

본 논문은 자동차용 시트의 내부에 설치되어 탑승자의 등 부위를 지지하여 편안한 승차감을 제공하는 자동차용 시트의 플라스틱 서스펜션 어셈블리 개발에 관한 것이다. 운전자의 허리를 균등하게 지지하여 주는 구조를 갖도록 설계하고 시트 백 프레임과 플라스틱 서스펜션이 원활하게 조합될 수 있는 구조로 개발하고자 한다. 체압 분포 특성을 고려하여 서스펜션의 단품을 설계하고 기능성을 평가하였다. 또한 실제와 동일한 사이즈의 서스펜션을 모델링하고 구조해석을 수행하였다. 기존 스프링 서스펜션과 새로 개발된 플라스틱 서스펜션의 해석결과 및 실제 측정값이 유사함을 확인하고 최적의 해석 및 설계를 확립하였다.

• 한국해양공학회지
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• 제22권6호
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• pp.75-82
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• 2008

Flame bending has been extensively used in the shipbuilding industry for hull plate forming In flame bending it is difficult to obtain the desired shape because the residual deformation dependson the complex temperature distribution and the thermal plastic strain. Mechanical bending such as reconfigurable press forming multi-point press forming or die-less forming has been found to improve the automation of hull plateforming because it can more accurately control the desired shape than line heating. Multi-point forming is a process in which external forces are used to form metal work-pieces. Therefore it can be a flexible and efficient forming technique. This paper presents an optimal approach to determining the press-stroke for multi-point press forming of curved shapes. An integrated configuration of Finite element analysis (FEA) and spring-back compensation algorithm is developed to calculate the strokes of the multi-point press. Not only spring-back is modeled by elastic plastic shell elements but also an iterative algorithm to compensate the spring-back is applied to adjust the amount of pressing stroke. An iterative displacement adjustment (IDA) method is applied by integration of the FEA procedure and the spring-back compensation work. Shape deviation between the desired surface and deform￡d plate is minimized by the IDA algorithm.