Investigation on Forming Behaviour of Sheet Metal by Test Using Cylindrical Cup with Hole

2018 ◽  
Vol 789 ◽  
pp. 51-58
Author(s):  
Bhadpiroon Watcharasresomroeng
Keyword(s):  
Sheet Metal ◽  
High Strength Steel ◽  
High Strength ◽  
Materials Testing ◽  
Drawing Ratio ◽  
Blank Holder ◽  
Steel Sheets ◽  
Fuel Consumption Rate ◽  
Materials Used ◽  
Cylindrical Cup

Nowadays, there are several grades of sheet metal used in the automotive industry. Highstrength steel sheets, particularly, have been widely used in order to reduce the weight of vehicles,which is strongly related to their fuel consumption rate. However, it is generally known that thestrength of the sheets, which is relatively higher than that of the conventional carbon steel sheets,results in their low formability. In this work, the limiting drawing ratio and forming behavior of sheetmetal that is conventionally used for automobile parts were evaluated by test using cylindrical cupwith hole. The feasibility to use limiting cup height for comparing formability of sheet metal was alsoincluded in the investigation. The sheet materials used in the experiments are aluminium, cold rolledsteel, high strength steel and advanced high strength steel. The process parameters for this study weredie corner radius and blank holder force. Workpiece materials were prepared with a circular shapeand with a diameter of 80 millimetres. In the center of the circular workpiece, a 12-millimetrediameter hole was drilled to observe the formability of each of the materials. The advantage of usingan initial blank with a hole in the center by the cylindrical cup drawing test is that the cup does notfail from changes of the thickness of material near the punch radius at the bottom of the cup. Thelimiting cup height of the investigated materials were evaluated by test using the cylindrical cup withhole. The results show that the limiting cup height values have a relationship to the limiting drawingratio values of the investigated materials. Testing using cylindrical cup with hole by evaluating thelimiting cup height value is feasible for comparing the formability of sheet metals.

Reduction of Springback in Hat Channel with High-Strength Steel Sheetby Stroke Returning Deep Drawing

2013 ◽  
Vol 554-557 ◽  
pp. 1320-1330 ◽  
Author(s):  
Taro Geka ◽  
Masayuki Asakura ◽  
Takuma Kiso ◽  
Takashi Sugiyama ◽  
Masato Takamura ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Deep Drawing ◽  
High Strength Steel ◽  
High Strength ◽  
New Method ◽  
Dual Phase ◽  
High Tensile Strength ◽  
Blank Holder ◽  
Steel Sheets

This study investigated the twisting phenomenon in curved hat channel products made of dual-phase 980-MPa-class high-tensile-strength steel sheets. The stroke returning deep drawing (SRDD) method was proposed to deal with twisting. In this new method, after the punch reaches the bottom dead point, it returns to a certain drawing height without the blank holder being removed. With the application of the SRDD method, twisting hardly occurred, but sidewall curl increased. A two-step SRDD was then proposed to reduce the sidewall curl of SRDD products. In the two-step SRDD method, a stroke returning process is carried out in two steps under different conditions. The results showed that the two-step SRDD method reduced the sidewall curl and twist simultaneously.

Finite Element Analysis of Reinforcement Rocker Part Made from JAC780Y Steel Sheets

2021 ◽  
Vol 877 ◽  
pp. 83-89
Author(s):  
Aeksuwat Nakwattanaset ◽  
Surasak Suranuntchai
Keyword(s):  
Finite Element ◽  
Sheet Metal ◽  
High Strength Steel ◽  
High Strength ◽  
Material Model ◽  
Advanced High Strength Steel ◽  
Forming Process ◽  
Element Analysis ◽  
Steel Sheets ◽  
Springback Prediction

The manufacturing industries for automotive parts aim to develop technologies for reducing vehicle weight in order to decrease fuel consumption. However, passive safety function for drivers and passengers must not be impaired or should be even improved. Therefore, advanced high strength steel sheet plays more and more important role in designing automotive components. Nowadays, prediction of formability for sheet metal stamping has high capability more than the past. The major challenge is springback prediction. Moreover, it assists in the tooling design to correctly compensate for springback. Especially in automotive production, springback effects have been generally exhibited distinct after forming process of the high strength steel sheets. The springback effect occurred in the deformed state of metal parts must be taken into account by designing any sheet metal panels. Then, the purpose of the present research is to investigate the springback phenomenon of an automotive part named Reinforcement Rocker RL made from an advanced high strength steel grade JAC780Y, after stamping. In addition, the tools design has been carried out. Finite Element (FE) program known as DYNAFORM (based on LS-DYNA solver), has been applied to analyze and improve the springback effect on such forming part. An anisotropic material model according to type 36 (MAT_036 3-PARAMETER_BARAT) was applied. The results obtained from simulations were compared with required parts in each section. Then, the die surface from compensation in 2nd step forming was modified to use. Finally, the simulation part was verified with the real stamping part. It was found that the finite element simulation showed high capability for prediction and compensation of springback in high strength steel sheets forming.

scholarly journals Mechanical clinching and self-pierce riveting for sheet combination of 780-MPa high-strength steel and aluminium alloy A5052 sheets and durability on salt spray test of joints

2021 ◽  
Vol 113 (1-2) ◽  
pp. 59-72
Author(s):  
Yohei Abe ◽  
Ken-ichiro Mori
Keyword(s):  
Aluminium Alloy ◽  
High Strength Steel ◽  
Salt Spray ◽  
High Strength ◽  
Alloy Sheet ◽  
Galvanized Steel ◽  
Load Reduction ◽  
Minimum Thickness ◽  
Steel Sheets ◽  
Mechanical Clinching

AbstractTo increase the usage of high-strength steel and aluminium alloy sheets for lightweight automobile body panels, the joinability of sheet combinations including a 780-MPa high-strength steel and an aluminium alloy A5052 sheets by mechanical clinching and self-pierce riveting was investigated for different tool shapes in an experiment. All the sheet combinations except for the two steel sheets by self-pierce riveting, i.e., the two steel sheets, the two aluminium alloy sheets, and the steel-aluminium alloy sheets, were successfully joined by both the joining methods without the gaps among the rivet and the sheets. Then, to show the durability of the joined sheets, the corrosion behaviour and the joint strength of the aged sheets by a salt spray test were measured. The corrosion and the load reduction of the clinched and the riveted two aluminium alloy sheets were little. The corrosion of the clinched two steel sheets without the galvanized layer progressed, and then the load after 1176 h decreased by 85%. In the clinched two galvanized steel sheets, the corrosion progress slowed down by 24%. In the clinched steel and aluminium alloy sheets, the thickness reduction occurred near the minimum thickness of the upper sheet and in the upper surface on the edge of the lower aluminium alloy sheet, whereas the top surface of the upper sheet and the upper surface of the lower sheet were mainly corroded in the riveted joint. The load reduction was caused by the two thickness reductions, i.e., the reduction in the minimum thickness of the upper sheet and the reduction in the flange of the aluminium alloy sheet. Although the load of the clinched steel without the galvanized coating layer and aluminium alloy sheets decreased by about 20%, the use of the galvanized steel sheet brought the decrease by about 11%. It was found that the use of the galvanized steel sheets is effective for the decrease of strength reduction due to corrosion.

The Analysis on the Stamping Formability of High Strength Steel

2021 ◽  
Vol 885 ◽  
pp. 3-9
Author(s):  
Wen Yu Ma ◽  
Jian Wei Yang ◽  
Ye Yao ◽  
Yong Qiang Zhang ◽  
Jun Zhang
Keyword(s):  
High Strength Steel ◽  
High Strength ◽  
Blank Holder Force ◽  
Blank Holder ◽  
Variable Blank Holder Force ◽  
Automotive Part ◽  
Blank Shape ◽  
Shaped Blank

Recently the high strength steel has been applied in the automotive more and more widely. In this study, the effect of blank shape on the formability of an automotive part was analyzed. The three kinds of blank shapes were chosen, including a rectangular shaped blank, a blank with two corners cut straightly and a blank with two corners cut in curve. The effect of the variable blank holder force on the formability was studied. The four kinds of variable blank holder force were applied. The blank shape in this part is the blank with two corners cut curve. The results show that the blank with two corners curve is the most suitable. And the blank holder force from 1000 kN to 1500 kN is the most useful for the formability.

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