scholarly journals Analysis of Sheet Metal Forming (Stamping Process): A Study of the Variable Friction Coefficient on 5052 Aluminum Alloy

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 853 ◽  
Author(s):  
Shasha Dou ◽  
Jiansheng Xia
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Sheet Metal ◽  
Boundary Lubrication ◽  
Thickness Distribution ◽  
Sliding Velocity ◽  
Spring Back ◽  
Stamping Die ◽  
Constant Friction ◽  
Variable Friction

Under a boundary lubrication regime, the effect of sliding velocity and normal loads on the friction coefficient in the sheet metal stamping process was investigated using a pin-on-disk sliding wear test. Software was used to analyze both the data generated and the friction coefficient; in addition, a variable friction model based on different velocities and normal loads was also initiated. Under different experimental conditions and numerous influences, both the analysis and microtopography examination of sheet metal helped to obtain the mechanism influence on the friction coefficient. Through further analysis of the microtopography of sheet metal, the law of the surface roughness of sheet metal after grinding with stamping die was established. The model was established to simulate the thickness distribution and spring-back of U-bend parts using ABAQUS software. The results show that the friction coefficient values between the sheet metal and the stamping die generally decrease with increasing sliding velocity and normal loads, and the decreasing tendency slows down under a higher sliding velocity and normal load. Furrow wear and abrasive wear are the main wear mechanisms, with slight sticking wear under the boundary lubrication; the surface roughness after grinding with stamping die generally increases with increasing normal loads and decreasing sliding velocity. The predicted results of thickness distribution with a constant friction coefficient of 0.1 and with the variable friction coefficient model are more consistent with the actual measured values, but the predicted accuracy of spring-back in the variable friction coefficient model is higher than that of the constant friction coefficient model.

scholarly journals Analysis of Sheet Metal Forming (Warm Stamping Process): A Study of the Variable Friction Coefficient on 6111 Aluminum Alloy

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1189
Author(s):  
Shasha Dou ◽  
Xiaoping Wang ◽  
Jason Xia ◽  
Lisa Wilson
Keyword(s):  
Aluminum Alloy ◽  
Friction Coefficient ◽  
Normal Load ◽  
Thickness Distribution ◽  
Simulation Software ◽  
Spring Back ◽  
Sliding Speed ◽  
Test Measurement ◽  
Variable Friction

Aluminum alloy materials have been widely used in automobile, aerospace and other fields because of their low density, high specific strength and corrosion resistance. The process of the warm forming of aluminum alloy improves the formability of aluminum alloy sheets, reduces the deformation resistance and spring-back and improves the forming accuracy and quality of parts. For these reasons, it is frequently used. In this work, the effects of temperature, sliding speed and normal load on the friction coefficient of 6111 aluminum alloy were studied by using a CFT-I (Equipment Type) friction tester under boundary lubrication conditions. The surface morphology of the sample after the friction test was observed by optical microscopy. The results show that the surface quality of aluminum alloy is better at 200 °C, which was used as the temperature in the experiments. According to the test measurement results, the friction coefficient increases with the increase in temperature and decreases with the increase in sliding speed and normal load. Variable friction coefficient models of sliding speed and normal load were established. Using the optimal parameter combination as the simulation parameter, the established variable friction coefficient models were input into numerical simulation software, and two sets of comparative simulations were established. The thickness distribution of the sheet material obtained through the simulation was compared with the actual test measurement. Further verification was carried out through the amount of spring-back. The results show that the thickness distribution and spring-back of the sheet obtained by the variable friction coefficient model are closer to the actual measurements (the error of the spring-back angle decreased from more than 20% to less than 10%), which verifies the reliability and accuracy of the variable friction coefficient model.

The Relation Between the Friction of Lubricated Rough Surfaces and Apparent Normal Pressure

1989 ◽  
Vol 111 (2) ◽  
pp. 260-264 ◽  
Author(s):  
P. Lacey ◽  
A. A. Torrance ◽  
J. A. Fitzpatrick
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Boundary Lubrication ◽  
Slip Line ◽  
Field Model ◽  
Rough Surfaces ◽  
Normal Pressure ◽  
Line Field ◽  
Slip Line Field ◽  
Asperity Contacts

Most previous studies of boundary lubrication have ignored the contribution of surface roughness to friction. However, recent work by Moalic et al. (1987) has shown that when asperity contacts can be modelled by a slip line field, there is a precise relation between the friction coefficient and the asperity slope. Here, it is shown that there is also a relation between the friction coefficient and the normal pressure for rough surfaces which can be predicted from a development of the slip line field model.

Effect of variable friction coefficient on sheet metal drawing

2002 ◽  
Vol 35 (2) ◽  
pp. 97-104 ◽  
Author(s):  
Haluk Darendeliler ◽  
Metin Akkök ◽  
Can Ali Yücesoy
Keyword(s):  
Friction Coefficient ◽  
Sheet Metal ◽  
Variable Friction

scholarly journals Effect of Process Parameters and Preheating Temperature on Surface Roughness and Thickness Distribution in Hole Flanging using Incremental Sheet Metal Forming

2019 ◽  
Vol 8 (12S2) ◽  
pp. 84-87
Keyword(s):  
Surface Roughness ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Thickness Distribution ◽  
Research Work ◽  
Preheating Temperature ◽  
Incremental Sheet Metal Forming ◽  
Best Parameter ◽  
Hole Flanging

Incremental Sheet metal forming is a die less method of forming which offers high formability. In this research work; effect of step depth, tool rotation speed and preheating temperature on surface roughness and thinning of flange wall is investigated in hole flanging using incremental forming. The parameter optimization is carried out by Taguchi method. Grey relational analysis is carried out to obtain best parameter combination.

scholarly journals Theoretical and Experimental Investigation on Friction in Lubricated Line Contacts with Different Materials and Textures in Presence of Wear

2016 ◽  
Vol 681 ◽  
pp. 142-154 ◽  
Author(s):  
Francesca Di Puccio ◽  
Enrico Ciulli
Keyword(s):  
Surface Roughness ◽  
Experimental Investigation ◽  
Friction Coefficient ◽  
Boundary Lubrication ◽  
Flat Surface ◽  
Surface Conditions ◽  
Lubrication Regimes ◽  
Line Contacts ◽  
Lubrication Conditions ◽  
Theoretical Procedure

An experimental investigation on the friction coefficient in line contacts under mixed and boundary lubrication regimes is described. Rectangular contacts between cylindrical specimens and the flat surface of discs of different material and surface roughness combinations were analyzed. Very low Stribeck numbers have been considered, resulting also in low dimensionless film thickness, so that the morphology of the surfaces and the material had a remarking role. In this work, the theoretical procedure for assessing the friction coefficient in the tested cases is described and compared to experimental results. Additionally, wear effects obtained in boundary lubrication conditions are shown. The surface conditions are put in relation with some particular trends of the friction coefficient obtained for certain combinations of materials and roughness.

scholarly journals Effect of Process Parameters and Preheating Temperature on Surface Roughness and Thickness Distribution in Hole Flanging using Incremental Sheet Metal Forming

2019 ◽  
Vol 9 (2) ◽  
pp. 666-669
Keyword(s):  
Surface Roughness ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Thickness Distribution ◽  
Research Work ◽  
Preheating Temperature ◽  
Incremental Sheet Metal Forming ◽  
Best Parameter ◽  
Hole Flanging

Incremental Sheet metal forming is a die less method of forming which offers high formability. In this research work; effect of step depth, tool rotation speed and preheating temperature on surface roughness and thinning of flange wall is investigated in hole flanging using incremental forming. The parameter optimization is carried out by Taguchi method. Grey relational analysis is carried out to obtain best parameter combination.

scholarly journals Effects of varying friction coefficient on rolling pressure distribution

2019 ◽  
Vol 37 (2) ◽  
pp. 11-25
Author(s):  
F. Davis ◽  
A. Andrews ◽  
M. N. Sackey ◽  
S. P. Owusu-Ofori
Keyword(s):  
Plastic Deformation ◽  
Friction Coefficient ◽  
Pressure Distribution ◽  
Deformation Process ◽  
Contact Region ◽  
Quantitative Relationship ◽  
Current Approach ◽  
Roll Pressure ◽  
Constant Friction ◽  
Variable Friction

Accurate characteristics of roll pressure distribution is essential in the estimation of the energy and power requirements for parts undergoing plastic deformation. The nature of the pressure distribution is very sensitive to the friction coefficient between the roller and the deformed part. The physics of the deformation process points to a variable friction coefficient, however, current research and practices result in the use of a constant friction coefficient. This work explored the development of a technique to determine a quantitative relationship between the variable friction coefficient and the process parameters. The pressure distribution was then developed within the contact region using the variable friction coefficient model. Results show that current approach used by industry (‘the rule of thumb’) overestimates the pressure distribution, compared to the current research, thus wasting power needed for the rolling operation by about 18%. Keywords: Rolling; varying friction coefficient; pressure distribution; power 

Research on Box Drawing Coefficient of Friction Based on Dynaform

2012 ◽  
Vol 628 ◽  
pp. 223-228
Author(s):  
Zhi Gao Luo ◽  
Xu Dong Li ◽  
Jing Jing Zhang ◽  
Jun Li Zhao
Keyword(s):  
Friction Coefficient ◽  
Sheet Metal ◽  
Deep Drawing ◽  
Metal Forming ◽  
Thickness Distribution ◽  
Forming Limit ◽  
Drawing Process ◽  
Analysis Software ◽  
Element Analysis ◽  
Wall Thickness Distribution

The box body drawing process is prone to breakage defect. Using finite element analysis software Dynaform5.7, the box part in deep drawing process was simulated. The friction coefficient was observed to change between sheet metal and die. Analysis of sheet metal forming limit and wall thickness distribution，therefore came out with the following conclusion：box deep drawing is affected by the lubrication , when the friction coefficient is lower than 0.17, Lubrication can effectively prevent the box shaped parts from cracks. At the same time, the research still is developing a new drawing.

Cutting performance investigation based on the variable friction model by considering sliding velocity and limiting stress

2020 ◽  
Vol 234 (8) ◽  
pp. 1113-1123
Author(s):  
Xin Li ◽  
Zhenyu Shi ◽  
Ningmin Duan ◽  
Peng Cui ◽  
Shuai Zhang ◽  
...  
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Finite Element Model ◽  
Cutting Force ◽  
Element Model ◽  
Friction Model ◽  
Rake Face ◽  
Sliding Velocity ◽  
Variable Friction ◽  
Simulation Results

Fast and accurate cutting force prediction is still one of the most complex problems and challenges in the machining research community. In this study, a modified finite element model is presented to predict cutting force and cutting length in turning operations of AISI 1018. Unlike the existing research, in which the mean friction coefficient μ was taken, a variable friction coefficient μ involving the sliding velocity between chip and tool is presented in this article. The sticking–sliding friction model is adopted, and the maximum limiting stress in sticking region is calculated by considering the thermal softening and normal stress distribution. Experiments have been performed for machining AISI 1018 using tungsten carbide tool, and simulation results have been compared to experiments. The simulation results of the modified finite element model have shown better outputs in predicting cutting force, tangential force, and tool–chip contact length on the rake face. The results of this article not only are meaningful to optimize tool design and cutting parameters but also can provide a clear understanding of contact behavior between tool rake face and chip.

Static Friction of Contacting Real Surfaces in the Presence of Sub-Boundary Lubrication

1998 ◽  
Vol 120 (2) ◽  
pp. 296-303 ◽  
Author(s):  
A. A. Polycarpou ◽  
Izhak Etsion
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Film Thickness ◽  
Boundary Lubrication ◽  
Normal Load ◽  
Static Friction ◽  
Liquid Films ◽  
Adhesion Forces ◽  
Static Friction Coefficient ◽  
Magnetic Hard Disk

A model for calculating the static friction coefficient of contacting real (rough) surfaces in the presence of very thin liquid films (sub-boundary lubrication) is developed. The liquid has a very high affinity for the surfaces and its thickness is of the order of the surface roughness average. An extension of the Greenwood and Williamson (GW) asperity model and an improved Derjaguin, Muller and Toporov (DMT) adhesion model are utilized for calculating the contact and adhesion forces, respectively. The effects of the liquid film thickness and the surface topography on the static friction coefficient are investigated. A critical film thickness is found above which the friction coefficient increases sharply. The critical thickness depends on the surface roughness and the external normal load. This phenomenon is more profound for very smooth surfaces and small normal loads, in agreement with published experimental work on magnetic hard disk interfaces.

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