scholarly journals Comparative study of wall thickness change at deep drawing of box-shaped product using flat restriction bars

2013 ◽  
Vol 30 (85(4/2013)) ◽  
pp. 431-443
Author(s):  
Juraj Hudák ◽  
Miroslav Tomáš
Keyword(s):  
Comparative Study ◽  
Wall Thickness ◽  
Deep Drawing ◽  
Thickness Change

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.

Comparative Study on Design of Exposed Penstock Laid on Ground Using Chinese and American Specifications

2014 ◽  
Vol 580-583 ◽  
pp. 2000-2006
Author(s):  
Lei Hu ◽  
He Gao Wu ◽  
Chang Zheng Shi ◽  
Ying Han Xie
Keyword(s):  
Comparative Study ◽  
Wall Thickness ◽  
Structural Design ◽  
Shell Thickness ◽  
Pressure Vessels ◽  
Hydropower Station ◽  
Allowable Stress ◽  
Direct Factor ◽  
Safety Coefficient ◽  
Load Combination

In this paper, differences by using selected three typical specifications—DL/T 5141-2001 (Chinese), ASCE No.79 in the version of 1993(American) and ASCE No.79 in the version of 2012 (American)—in structural design of exposed steel penstock were explored. A practical example about exposed penstock laid on ground applied in hydropower station was also used to analyze specifications clearly. The result shows that the main differences between Chinese and American specifications are allowable stress and load combination. The former is direct factor of calculating exposed penstock shell thickness. Therefore, ASCE No.79 (2012) designs the minimum wall thickness, followed by DL/T 5141-2001 and the last is ASCE No.79 (1993), which is correspondingly contrary to sort by allowable stress. Basically, ASCE No.79 (2012) defines lower safety coefficient for exposed penstock, which is identical with authoritative rules of pressure vessels in the U.S.A and EU. The safety of DL/T 5141-2001 has been proved via rich engineering experience and this specification is recommended for Chinese projects. Besides, ASCE No.79 (2012) is recommended.

Simulation and Optimization on Dynamic Hydraulic Drawing for Spiral Bottom Shell Parts

2014 ◽  
Vol 496-500 ◽  
pp. 935-938
Author(s):  
Wen Chao Zhou ◽  
Wei Zhou ◽  
Cun Ping Liu ◽  
Shan Hua Xiao
Keyword(s):  
Wall Thickness ◽  
Deep Drawing ◽  
Fluid Pressure ◽  
Processing Parameters ◽  
Key Factors ◽  
Forming Process ◽  
Simulation And Optimization ◽  
Simulation Process ◽  
Optimal Processing ◽  
Blank Shape

The dynamic hydraulic drawing simulation is a valid method that reduces costs, increases quality and discovers hydraulic forming process problems.The simulation process of hydraulic drawing for spiral bottom brake shell parts with space surface feature was investigated and the optimal processing parameters were acquired by using Dynaform software. The results showed that model approaches, model methods, meshing and parameters setting were the foundation of hydraulic drawing simulation and the optimized control of holder force and fluid pressure were the key factors for preventing defects during hydraulic deep drawing. Meanwhile, the suitable blank shape was found good for reducing the defects of Wall Thickness Unevenness and oral flange earing, etc.

A comparative study of deep drawing with conventional, isostatic, and hydrostatic pressure

1982 ◽  
Vol 6 (2-3) ◽  
pp. 227-234 ◽  
Author(s):  
R. Narayanaswamy ◽  
S.M. Doraivelu ◽  
V. Gopinathan ◽  
V.C. Venkatesh
Keyword(s):  
Hydrostatic Pressure ◽  
Comparative Study ◽  
Deep Drawing

scholarly journals Physical Modelling and Numerical Simulation of the Deep Drawing Process of a Box-Shaped Product Focused on Material Limits Determination

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1058 ◽  
Author(s):  
Miroslav Tomáš ◽  
Emil Evin ◽  
Ján Kepič ◽  
Juraj Hudák
Keyword(s):  
Plastic Strain ◽  
Deep Drawing ◽  
Scaling Laws ◽  
Strain Ratio ◽  
Physical Models ◽  
Scale Model ◽  
Drawing Process ◽  
Plastic Strain Ratio ◽  
Thickness Change ◽  
Deep Drawing Process

Similitude theory helps engineers and scientists to accurately predict the behaviors of real systems through the application of scaling laws to the experimental results of a scale model related to the real system by similarity conditions. The theory was applied when studying the deep drawing process of a bathtub made from cold rolled low carbon aluminum-killed steel from the point of view of material limits. The bathtub model was created on the basis of geometric, physical, and mechanical similarity on a scale of 1:5. Thus, simulations and physical models were created. The simulation model was used to verify the combination yield locus/hardening law on the basis of comparing the thickness change. As a result, Hill 48/Krupkowski showed the minimal deviation by comparing data evaluated from numerical simulations and that measured on the physical model. Additionally, material anisotropy was modelled when virtual materials were defined from experimentally measured values of the plastic strain ratio. As an outcome, extra deep drawing quality steel with an average plastic strain ratio of rm ≥ 1.47 and an average strain hardening exponent of nm ≥ 0.23 must be used for the deep drawing of the bathtub.

Change of Plastic Hinge Position in Radial Ring Rolling without Guide-Roll

2010 ◽  
Vol 42 ◽  
pp. 30-34
Author(s):  
Yong Xing Hao ◽  
Su Juan Shi ◽  
Lv Yun Yang ◽  
Song Wei Yang
Keyword(s):  
Wall Thickness ◽  
Plastic Hinge ◽  
Position Angle ◽  
Rolling Process ◽  
Ring Rolling ◽  
Thickness Change ◽  
Plastic Deformation Process ◽  
Hinge Position ◽  
Ring Rolling Process ◽  
Rolling Deformation

Radial ring rolling is an unsteady plastic deformation process. Internal stress of the ring is foundation of formation of the plastic hinge. The radial wall thickness of ring changes gradually along ring circumferential direction. Theoretical analysis and FE simulation show that: the plastic hinge is not always exactly opposite to the rolling deformation zone in ring rolling process without guide-roll. The plastic hinge position angle β0 is affected by ratio of rolling entrance wall thickness H0 and rate of wall thickness change η. Curve of β0-H0/η is shaped as double U staggered relative to each other. With the H0/η increasing, β0 reduces gradually and approaches to π in the range of H0/η>6.28. H0/η>14.6H0/R2. Only when the rolling process is steady, and H0≈R2, β0 is greater than π, and approximates to π. The β0 fluctuates dramatically when H0/η≈5.71. In some cases, H0/η may fluctuate in 0 to 6.28, leading to the instability of plastic hinge position.

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