scholarly journals The Effect of Surface Angle of Flowing Sheet on The Limit Drawing Ratio and The Wall Thickness Change in Drawing of Spherical Bottom Cups

2018 ◽  
Vol 18 (3) ◽  
pp. 1149-1157
Author(s):  
Cebeli Özek ◽  
Engin ÜNAL
Keyword(s):  
Wall Thickness ◽  
Drawing Ratio ◽  
Limit Drawing Ratio ◽  
Thickness Change ◽  
Spherical Bottom ◽  
Surface Angle ◽  
Effect Of Surface

The Maximum Drawing Ratio in Hydroforming Processes

1990 ◽  
Vol 112 (1) ◽  
pp. 47-56 ◽  
Author(s):  
S. Yossifon ◽  
J. Tirosh
Keyword(s):  
Failure Modes ◽  
Fluid Pressure ◽  
Radius Of Curvature ◽  
Strain Hardening Exponent ◽  
Drawing Ratio ◽  
Limit Drawing Ratio ◽  
Normal Anisotropy ◽  
Geometrical Properties ◽  
Buckling Instability ◽  
Hydroforming Process

The concept of Maximum Drawing Ratio (MDR), supplementary to the well-known Limit Drawing Ratio (LDR), is defined, examined, and illustrated by experiments. In essence the MDR is reached when the two basic failure modes, namely: rupture (due to tensile instability) and wrinkling (due to buckling instability) are delayed till they occur simultaneously. Thus the process is beneficially utilized for higher drawing ratio by postponing earlier interception of either one of the above failures alone. The ability to suppress (up to a certain extent) the appearance of these failure modes depends heavily on the fluid-pressure path which controls the hydroforming process. The effect of the material properties, like the strain hardening exponent, the normal anisotropy of the blank, etc., as well as the geometrical properties (i.e., the thickness of the blank, the radius of curvature at the lip, etc.) on the MDR, are considered here in some detail. The nature of the solutions by which MDR is reached is discussed.

The limit drawing ratio and formability prediction of advanced high strength dual-phase steels

2011 ◽  
Vol 32 (6) ◽  
pp. 3320-3327 ◽  
Author(s):  
Wang Wu-rong ◽  
He Chang-wei ◽  
Zhao Zhong-hua ◽  
Wei Xi-cheng
Keyword(s):  
High Strength ◽  
Drawing Ratio ◽  
Dual Phase ◽  
Limit Drawing Ratio ◽  
Dual Phase Steels ◽  
Formability Prediction

Effect of Precompression on Thickness of Pipe During Bending

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
A. V. Kale ◽  
H. T. Thorat
Keyword(s):  
Cross Section ◽  
Wall Thickness ◽  
Horizontal Plane ◽  
Circular Cross Section ◽  
Thickness Variation ◽  
Parallel Plates ◽  
Thickness Change ◽  
Maximum Deformation ◽  
Curved Pipes ◽  
Tension And Compression

Straight pipes with a circular cross section are processed into smooth bends by various pipe bending techniques. After bending, the initial circular cross section is deformed with thickness change. These changes from ideal are normally referred to as “ovality” and “thinning.” Their influence on the subsequent behavior of curved pipes is not yet fully understood. The aim of this paper is to present a factual method to reduce thinning of the wall thickness of pipe during bending. A new mechanism is developed for bending of pipes. This mechanism has a provision of precompression (radial squeeze) of the pipe along the directrix of maximum deformation during bending. This is achieved by clamping the pipe using two parallel plates from top and bottom. In fact, the pipe is wrapped using two rollers—one from inside and one from outside in the horizontal plane—and two plates parallel to the horizontal plane—one from the top and one from the bottom. Experimentation is carried out on this mechanism, and thicknesses are measured at the grid points along the length of the pipe. From the experimental values of thicknesses on the tension and compression sides, dimensionless variations in wall thickness of various groups of pipes are computed for different precompression values. In order to represent the thickness at any point, a mathematical equation is derived. Analytical values of thickness variations on tension and compression sides are computed using this equation. Experimental and analytical results are compared, and its methodical approach is presented in this paper. Results show that precompression reduces thickness variation of the pipe after bending.

Comparison of Microstructure and Mechanical Behavior of the Ferritic Stainless Steels ASTM 430 Stabilized with Niobium and ASTM 439 Stabilized with Niobium and Titanium

2016 ◽  
Vol 879 ◽  
pp. 1651-1655 ◽  
Author(s):  
Leandro Paulo de Almeida Reis Tanure ◽  
Cláudio Moreira de Alcântara ◽  
Tarcísio Reis de Oliveira ◽  
Dagoberto Brandão Santos ◽  
Berenice Mendonça Gonzalez
Keyword(s):  
Stainless Steels ◽  
Lower Cost ◽  
Volume Fraction ◽  
Austenitic Stainless Steels ◽  
Total Elongation ◽  
Drawing Ratio ◽  
Limit Drawing Ratio ◽  
Soaking Time ◽  
Ferritic Stainless Steels ◽  
Cold Rolled

The use of Ferritic Stainless Steels has become indispensable due its lower cost and the possibility to replace austenitic stainless steels in many applications. In this study, cold rolled sheets of two stabilized ferritic stainless steels with 85% thickness reduction were annealed by applying a heating rate of 24 oC/s and a soaking time of 24 s. The niobium stabilized ferritic stainless steel type ASTM 430 (430Nb) was annealed at 880 oC while the niobium and titanium bi-stabilized steel ASTM 439 was annealed at 925 oC. The annealed samples were tensile tested and due to the smaller grain size, steel 430Nb, showed a higher yield stress and a higher total elongation. Concerning drawability the steel ASTM 439 presented a better performance with higher average R-value, lower planar anisotropy coefficient and a greater value for Limit Drawing Ratio (LDR). These results are explained in terms of the differences in size and volume fraction of precipitates between the two steels.

Experimental Study of Drawing Process With Servo Press

2007 ◽  
Author(s):  
Pei-Lum Tso ◽  
Hsin-Kai Liu ◽  
Cheng-Ho Li
Keyword(s):  
Software Package ◽  
Failure Criteria ◽  
Drawing Ratio ◽  
Drawing Process ◽  
Limit Drawing Ratio ◽  
Real Experiment ◽  
Drawing Speed ◽  
Servo Press ◽  
Two Indices ◽  
Maximum Limit

Servo presses providing flexible ram motions are extensively developed nowadays; the merit of such presses is the capability of generating versatile punch motions to fulfill the stamping. This paper studies a cup-shaped drawing process using a servo press. The aim of this research is to study the effect of the forming speed on preventing the cracks and wrinkles in drawing. A finite element method (FEM) software package—ABAQUS®, is utilized to predict the distribution of displacement stress, strain of the work material in drawing. Crack (related to thinning behavior) and wrinkle are two indices of the drawing failure criteria in simulation. An optimal forming speed could be estimated by simulation. The optimal forming speed would cause the maximum limit drawing ratio which is beneficial to prevent drawing failure. The analytical results were verified experimentally. The results show that the predicted drawing speed was consistent with the real experiment and simulation.

Drawability of Ti-6Al-4V Sheet at Elevated Temperatures

2010 ◽  
Vol 654-656 ◽  
pp. 902-905 ◽  
Author(s):  
Nho Kwang Park ◽  
Jin Gee Park ◽  
Sang Hyun Seo ◽  
Jeoung Han Kim
Keyword(s):  
Residual Stresses ◽  
Slip System ◽  
Process Parameters ◽  
Elevated Temperatures ◽  
Plastic Anisotropy ◽  
Drawing Ratio ◽  
Limit Drawing Ratio ◽  
Blank Holding Force ◽  
Forming Temperature ◽  
Increasing Temperature

Titanium and its alloys are difficult-to-form materials due to limited slip system and plastic anisotropy. Titanium is also prone to change in color due to oxidation at high temperatures. It is thus advisable to conduct deep drawing of titanium and its alloys at temperatures below 600°C. In this study, the drawability of Ti-6Al-4V sheet is evaluated in respect to the process parameters such as forming temperature, forming speed, and blank holding force at elevated temperatures. It is shown that the limit drawing ratio (LDR) increases with increasing temperature, but varies insignificantly with forming speed. The development of residual stresses in the wall of drawn cups during deformation was evaluated.

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