• 소성∙가공
• /
• 제20권6호
• /
• pp.456-460
• /
• 2011

A major source of difficulty in die design for high strength steel is the high level of elastic recovery during unloading. The degree of elastic recovery is affected by factors such as material strength, bending angle, punch's corner radius and sheet thickness. Finite Element Method was used in the present work to quantitatively analyze the elastic recovery for various combinations of these parameters. In some cases elastic recovery happened in reverse direction. This phenomenon, which we call spring-go, was explained via changes in stress distribution in the panel occurring in the forming process.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2001년도 추계학술대회 논문집
• /
• pp.102-105
• /
• 2001

The spring back taking place after the coiling process of steam generator tube leads to the dimensional inaccuracy. In order to reduce the spring back, tension force was applied to the one end of the tube during forming. In this work, parametric study using FEM was performed to find the appropriate magnitude of tension force. The force that induces minimum suing back was found by simultaneously taking account of suing back amount, cross-sectional ovality, and thickness of the tube wall after deformation. In addition, stress relieving by heat treatment was also simulated as an alternative to the former method. The latter was found to be more effective under the given constraints.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2003년도 추계학술대회논문집
• /
• pp.144-147
• /
• 2003

In order to evaluate spring-back behavior in automotive sheet forming processes, a panel shape idealized as a SS-rail has been investigated. After spring-back kas been predicted fer SS-rails using the finite element analysis, results has been compared with experimental measurements for three automotive sheets. To account for hardening behavior such as the Bauschinger and transient effects in addition to anisotropic behavior, the combined isotropic-kinematic hardening law based on the Chaboche type single-surface model and a recently developed non-quadratic anisotropic yield function have been utilized, respectively.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 추계학술대회 논문집
• /
• pp.825-828
• /
• 1997

The market share of plastic fuel tube in automobile part is now growing rapidly. Especially fuel tube makers have had their efforts to develop tube module not only with dimensional accuracy, spring back and cost competitiveness. In this study, we used steam bending process for heat relaxation on PA12 plastic fuel tube's 128 types experimental bending conditions. we present the results of this process system in term of dimensional accuracy, and spring back.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2000년도 춘계학술대회 논문집
• /
• pp.837-841
• /
• 2000

Spinning process is a chipless metal forming method for axi-symmetric parts, which is more economical, efficient and versatile method of producing parts than the other sheet metal forming process such as stamping or deep drawing. It is a point deformation process where a metal disc. cylinderical workpiece. or preform in contact with a rotating chuck is plastically deformed by axial or axial-radial Motions of a tool or roller. in this study the variation of spring back with respect to various forming roller corner radius(Rr) and angle of roller holder($\alpha$) is investigated. Good as a result will help to get more precise shape by control of spring back.

• 소성∙가공
• /
• 제22권6호
• /
• pp.303-309
• /
• 2013

Spring-back of MS1470 steel sheets was numerically predicted using a non-linear kinematic hardening material behavior based on the Yoshida-Uemori model. From uniaxial tension and uniaxial tension-compression-tension data as well as the uniaxial tension-unloading-tension data, the parameters of the Yoshida-Uemori model were obtained. For the numerical simulations, the Yoshida-Uemori model was implemented into the commercial finite element program, ABAQUS/Explicit and ABAQUS/Standard using the user-defined material subroutines. The model performance was validated against the measured spring-back from the benchmark problems of NUMISHEET 2008 and NUMISHEET 2011, the 2-D draw bending test and the S-rail forming test, respectively.

• 한국산학기술학회논문지
• /
• 제14권1호
• /
• pp.28-32
• /
• 2013

본 연구에서는 프레스 부품의 스프링 백을 보정하기 위한 새로운 방법론을 제안하였다. 먼저, CAD 데이터와 측정데이터 사이의 오차를 비교하였다. 새로운 방법은 스프링 백을 보정하기 위한 수동적인 모델링 공정 대체가 가능한 3차원 측정데이터 기반의 자동 모델링을 제안하였다. 본 연구를 통해 프레스 부품의 스프링 백 보정을 위한 새로운 방법론을 적용하면 실제 공정에 소요되는 시간 및 비용 절감이 가능할 것으로 기대된다.

• 한국기계가공학회지
• /
• 제15권1호
• /
• pp.42-49
• /
• 2016

This study was analyed V-bending in order to analyze the spring-back phenomenon in the roll forming process. The material of forming sheet used in the roll forming process is high tension steel and the product name of sheet material is POSTEN 60. The most important variable is the number of roll passes (3-Pass, 4-Pass, 5-Pass, 6-Pass and 10-Pass) and other roll forming process variables were fixed. To determine the characteristics of the tension and compression, the forming sheet was analyzed by dividing the layer (Upper and Bottom) in the thickness direction from the center line. The results of FEM simulation analysis was derived to von-mises stress equivalent strain, and the spring-back value was calculated according to the final forming shape. The more number of the roll pass, von-mises stress and equivalent strain value of forming sheet were lowed. Also, spring-back values tended to decrease. The results of this study can be utilized for prediction and trend of spring-back value in the roll forming process applied to high tension steel sheet. So, development time and cost of the roll forming process is expected to be reduced.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2012년도 춘계학술대회 논문집
• /
• pp.925-926
• /
• 2012

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2011년도 춘계학술대회 논문집
• /
• pp.213-214
• /
• 2011