• 소성∙가공
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• 제10권7호
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• pp.534-542
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• 2001

Tubular hydroforming has attracted increased attention in the automotive industry recently. In this study, a professional finite element program for analysis and design of tube hydroforming processes, has been developed, called HydroFORM-3D, which is based on a rigid-plastic model. With the developed program HydroFORM-3D, the hydroforming process for an automobile lower arm is analyzed and designed. The manufacturing process for a lower arm consists of tube bending, preforming, and final hydroforming. To accomplish successful hydroforming process design, thorough investigation on proper combination of process parameters such as internal hydraulic pressure, axial feeding, and tool geometry is required. This paper describes the influences of forming conditions on the hydroforming of a lower arm by using simulation to predict strain and tube shape during bending, preforming, and final hydroforming processes.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.209-214
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• 2007

This study is concerned with working hardening of bending operation on hydroforming parts. Generally, hydroforming parts having the complicated shape of the automobile, require a 3-dimentional bending operation. This operation involves several variations in the tube which are the thickness, the mechanical characteristics, the hardness, the circumference etc., on original tube. So, we study those variations and the affect on the hydroforming operation and hydroforming parts. We used two methods, one of which was computer simulation and the other the actual test in the plant.

• 소성∙가공
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• 제10권1호
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• pp.3-14
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• 2001

Hydroforming is the technology using hydraulic pressure and forming sheet or tube metals to desired shape in a die cavity. lt can be characterized as tube hydroforming and sheet hydroforming depending on the shape of used blank. Due to its prcess-related benefits, this production technology has been remarkably noticed for great potential for feasible applications and recently gained great attraction from many industrials including automotive and non-automotive. This Paper analyzed the tube and the welded blank hydroforming process and compared formability of the processes for automotive engine mount bracket. The mathematical analysis was performed by using the dynamic explicit finite element code, PAM-STAMP. In tube hydroforming, bending, springback, and forming analysis were carried out and the effect of mandrel and axial feeding were examined. In welded blank hydroforming, pressure curve history is determined and the results of forming analysis were evaluated by the comparison of experimental results in the aspects of deformed shape and thickness distribution.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.262-265
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• 2003

In the present study, subframe was developed using hydroforming technology. The manufacturing process for subframe consists of tube bending, pre-forming and hydroforming. The effects of bending process for manufacturing hydroformed subframe were researched. And the variables of bending process were studied by FEM simulation. The bending method is rotary draw bending that is the most popular, cost-effective bending method for thin walled tubes.

• 한국생산제조학회지
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• 제9권3호
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• pp.160-168
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• 2000

Hydroforming is a metal forming process that enables circular metal tubes to be formed in to the parts with the complex cross section along the curved axial direction. Recently this hydroforming process is largely used for the production of the automotive parts. This paper presents the results of tube bending and hydroforming simulations in cases of the varying weld line positions of the tube. Ten cases of prebending and hydroforming simulations are carried out to find the optiaml weld line position.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.358-358
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• 2008

• 소성∙가공
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• 제9권5호
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• pp.504-511
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• 2000

Hydroforming is a forming process enabling circular metal tubes to be produced in complex cross sections along curved axial paths. This forming process is widely used to manufacture parts in automotive industry. This paper presents bending and forming results to following angle of weld line positions. These compare to good bending, bad bending and without weld line model case. And then this result of after forming compare to each forming cases. The purpose of this paper is found that adaptive weld line position for bended final shape.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.71-74
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• 2005

In manufacturing automotive parts, such as engine cradles, frame rails, subframes, cross-members, and other parts from circular tubes, pre-bending and pre-forming operations are often required prior to the subsequent tubular hydroforming process. During some pre-forming operations, the cross section of a bent circular tube is crushed into an oval-like shape to ensure proper geometry and sufficient clearance in the hydroforming dies. For such applications, the use of oval Instead of circular tubes could be an effective means of eliminating the pre-forming step. The oval tube could also be produced with less thinning and with less strain on the outside of the bend when controlled by a booster system without the use of mandrel. Hence, the understanding of the issues that occur in the bending of oval tubes is worthy of Investigation. This paper presents parametric studies on the bending of oval tubes without a mandrel. The finite element modeling technique is used to examine the deformation characteristics for both circular and oval tubes. In the simulations, the bending process parameters of bend radius, aspect ratio of the tube ovalness, and tube wall thickness are varied. Observations are made to obtain a hoop-buckle limit diagram in terms of a non-dimensional shape degradation factor. Suggestions based upon developed criteria are made on the acceptability of bend tubes suitable for hydroforming applications without the need ofa pre-forming step or the used of a mandrel.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.244-247
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• 2009

Hydroformed parts have higher dimensional accuracy, structural strength, and dimensional repeatability. Particularly in the automotive industry, manufacturing of parts with complex shapes from tubular materials sometimes requires one or more pre-forming operations such as bending before the hydroforming process. The pre-bending process is an important factor for successful hydroforming in the case where the perimeter of the blank is nearly the same as that of final product. The bendability of a tube depends on the parameters such as the bending radius, variation of the diameter, thickness, hardness. This study shows the analysis of bending through the stainless steel tubes bent to rotary draw bending machine.

• 소성∙가공
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• 제18권4호
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• pp.336-341
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• 2009

Hydroformed parts have higher dimensional accuracy, structural strength, and dimensional repeatability. Particularly in the automotive industry, manufacturing of parts with complex shapes from tubular materials sometimes requires one or more pre-forming operations such as bending before the hydroforming process. The pre-bending process is an important process for the successful hydroforming in the case where the perimeter of the blank is nearly the same as that of final product. The bendability of a tube depends on the parameters such as the bending radius, welding methods, mechanical properties and hardness. Through the stainless steel tubes bent by rotary draw bending machine, this study shows the following : (1) The influence on spring back ratio variation with stress level in the welded bent tube. (2) The Cross-section ovality variation with weld seam position and bending radius. (3) The relation between elongation and thickness reduction of tension zone with weld seam position and bending radius. (4) Workability evaluation of bent stainless steel tubes through the hardness of materials and hardness increment. The results of this study may help to understanding of characteristics on bendability of stainless steel tubes.