scholarly journals Determination of Hot Stamping Friction Coefficient of 7075 Aluminum

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1111
Author(s):  
Xiangji Li ◽  
Xu Yan ◽  
Zhiqiang Zhang ◽  
Mingwen Ren ◽  
Hongjie Jia
Keyword(s):  
Aluminum Alloy ◽  
Friction Coefficient ◽  
Thickness Distribution ◽  
Hot Stamping ◽  
Displacement Curve ◽  
Friction Behavior ◽  
Forming Quality ◽  
Forming Defects ◽  
Force Displacement ◽  
Lubrication Conditions

Aluminum alloy hot stamping technology can improve the formability of materials and obtain parts with high dimensional accuracy. Friction behavior in the hot stamping process is very important for forming quality. Accurate friction coefficient is helpful to improve the prediction accuracy of forming defects. It is hard to obtain the friction coefficient by simple experiments due to the complicated thermal–mechanical coupling and contact conditions during the hot stamping of aluminum alloys. In order to explore the effect of friction behavior on forming quality, hot stamping experiments of 7075 aluminum alloy U-shaped parts with different lubricants were carried out. The influence of different lubricants on the force–displacement curve, material inflow, surface appearance, and thickness distribution of the formed part was analyzed. The results showed that a good lubrication effect could be obtained with the molybdenum disulfide lubricant. The friction coefficient under different lubrication conditions was obtained by using the inverse problem optimization method. Compared with the experimental results, the determined friction coefficients could accurately predict the force–displacement curves and the thickness distributions of formed parts under different lubrication conditions.

scholarly journals Friction Characteristics Analysis of Symmetric Aluminum Alloy Parts in Warm Forming Process

Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 166
Author(s):  
Jiansheng Xia ◽  
Jun Zhao ◽  
Shasha Dou
Keyword(s):  
Finite Element ◽  
Aluminum Alloy ◽  
Friction Coefficient ◽  
Process Parameters ◽  
Friction Model ◽  
Forming Process ◽  
Friction Behavior ◽  
Forming Quality ◽  
Finite Element Software ◽  
Forming Defects

There are many typical symmetric large plastic deformation problems in aluminum alloy stamping. Warm stamping technology can improve the formability of materials and obtain parts with high-dimensional accuracy. Friction behavior in the stamping process is significant for the forming quality. An accurate friction coefficient is helpful in improving the prediction accuracy of forming defects. It is hard to obtain a unified and precise friction model through simple experiments due to the complicated contact conditions. To explore the effect of friction behavior on the forming quality, warm friction experiments of the AA6061 aluminum alloy and P20 steel with different process parameters were carried out using a high-temperature friction tester CFT-I (Equipment Type), including temperatures, the interface load, and sliding speeds. The variation curves of the friction coefficient with various parameters were obtained and analyzed. The results show that the friction coefficient increases with temperature and decreases with the sliding speed and load. Then, the influences of process parameters on the surface morphology of the samples after friction were observed by an optical microscope; adhesive wear occurred when the temperature increased, and the surface scratch increased and deepened with the increase in the load. Finally, the friction coefficient models of the speed and load were established by analyzing the data with Original software. Compared with the experimental and the finite element analysis results of the symmetrical part, the errors of the velocity friction model in thickness and springback angle are less than 4% and 5%, respectively. The mistakes of the load friction model are less than 6% and 7%, respectively. The accuracy of the two friction models is higher than that of the constant friction coefficient. Therefore, those coefficient models can effectively improve the simulation accuracy of finite element software.

Forming defects in aluminum alloy hot stamping of side-door impact beam

2014 ◽  
Vol 24 (11) ◽  
pp. 3611-3620 ◽  
Author(s):  
Jing ZHOU ◽  
Bao-yu WANG ◽  
Jian-guo LIN ◽  
Lei FU ◽  
Wen-yu MA
Keyword(s):  
Aluminum Alloy ◽  
Hot Stamping ◽  
Side Door ◽  
Forming Defects

EFFECT OF POLISHING ON THE FRICTION BEHAVIORS AND CUTTING PERFORMANCE OF BORON-DOPED DIAMOND FILMS ON WC-Co INSERTS

2014 ◽  
Vol 21 (03) ◽  
pp. 1450037 ◽  
Author(s):  
LIANG WANG ◽  
BIN SHEN ◽  
FANGHONG SUN ◽  
ZHIMING ZHANG
Keyword(s):  
Aluminum Alloy ◽  
Friction Coefficient ◽  
Adhesive Strength ◽  
Performance Enhancement ◽  
Diamond Films ◽  
Mechanical Polishing ◽  
Cutting Performance ◽  
Boron Doped Diamond ◽  
Friction Behavior ◽  
Boron Doped

Boron doped ( B -doped) diamond films are deposited onto WC- Co inserts by HFCVD with the mixture of acetone, trimethyl borate ( C 3 H 9 BO 3) and H 2. The as-deposited B -doped diamond films are characterized with scanning electron microscope (SEM), X-ray diffraction (XRD) spectroscopy, Raman spectroscopy, 3D surface topography based on white-light interferometry and Rockwell hardness tester. The effects of mechanical polishing on the friction behavior and cutting performance of B -doped diamond are evaluated by ball-on-plate type reciprocating tribometer and turning of aluminum alloy 7075 materials, respectively. For comparison, the same tests are also conducted for the bare WC- Co inserts with smooth surface. Friction tests suggest that the unpolished and polished B -doped diamond films possess relatively low fluctuation of friction coefficient than as-received bare WC- Co samples. The average stable friction coefficient for B -doped diamond films decreases apparently after mechanical polishing. The values for WC- Co sample, unpolished and polished B -doped diamond films are approximately 0.38, 0.25 and 0.11, respectively. The cutting results demonstrate that the low friction coefficient and high adhesive strength of B -doped diamond films play an essential role in the cutting performance enhancement of the WC- Co inserts. However, the mechanical polishing process may lower the adhesive strength of B -doped diamond films. Consequently, the polished B -doped diamond coated inserts show premature wear in the machining of adhesive aluminum alloy materials.

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 Influence of Process Parameters during Hot Stamping of AA6111 Aluminum Alloy Sheet

2012 ◽  
Vol 572 ◽  
pp. 255-260 ◽  
Author(s):  
Qing Lei Meng ◽  
Bao Yu Wang ◽  
Lei Fu ◽  
Jing Zhou ◽  
Jian Guo Lin
Keyword(s):  
Numerical Simulation ◽  
Aluminum Alloy ◽  
Process Parameters ◽  
Hot Stamping ◽  
Alloy Sheet ◽  
Aluminum Alloy Sheet ◽  
Influence Of Process Parameters ◽  
Blank Holding Force ◽  
Forming Temperature ◽  
Forming Defects

The AA6111 aluminum alloy sheet is widely used in auto-body manufacture. It can make use of good plasticity under high temperature to form more complex parts by using the hot stamping. The influence of process parameters in hot stamping of AA6111 aluminum alloy sheet is investigated through numerical simulation in this paper, including blank holding force (BHF), friction coefficient, stamping velocity and initial forming temperature. Finally forming defects of numerical simulation are verified through the hot stamping experiments. The results show that it can effectively avoid wrinkling and fracture by controlling the BHF, good lubricant is in favor of forming and numerical simulation can accurately predict forming defects to guide the production.

scholarly journals Study on improvement of prefolded energy absorption device to constant resistance and its mechanical properties

2021 ◽  
Vol 104 (3) ◽  
pp. 003685042110368
Author(s):  
Dong An ◽  
Jiaqi Song ◽  
Hailiang Xu ◽  
Jingzong Zhang ◽  
Yimin Song ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Energy Absorption ◽  
Compression Test ◽  
Side Wall ◽  
Concave Side ◽  
Displacement Curve ◽  
Static Compression ◽  
Constant Resistance ◽  
The Impact ◽  
Force Displacement

When the rock burst occurs, energy absorption support is an important method to solve the impact failure. To achieve constant resistance performance of energy absorption device, as an important component of the support, the mechanical properties of one kind of prefolded tube is analyzed by quasi-static compression test. The deformation process of compression test is simulated by ABAQUS and plastic strain nephogram of the numerical model are studied. It is found that the main factors affecting the fluctuation of force-displacement curve is the stiffness of concave side wall. The original tube is improved to constant resistance by changing the side wall. The friction coefficient affects the folding order and form of the energy absorbing device. Lifting the concave side wall stiffness can improve the overall stiffness of energy absorption device and slow down the falling section of force-displacement curve. It is always squeezed by adjacent convex side wall in the process of folding, with large plastic deformation. Compared with the original one, the improved prefolded tube designed in this paper can keep the maximum bearing capacity ( Pmax), increase the total energy absorption ( E), improve the specific energy absorption (SEA), and decrease the variance ( S2) of force-displacement curve.

scholarly journals Relationship between the real contact behavior and tribological characteristics of cotton fabric

Friction ◽  
2020 ◽  
Author(s):  
Rongxin Chen ◽  
Jiaxin Ye ◽  
Wei Zhang ◽  
Jiang Wei ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Contact Area ◽  
Dynamic Change ◽  
Tribological Characteristics ◽  
Real Contact Area ◽  
Cotton Fibers ◽  
Friction Behavior ◽  
Contact Behavior ◽  
The Real ◽  
Real Contact

Abstract The tribological characteristics of cotton fibers play an important role in engineering and materials science, and real contact behavior is a significant aspect in the friction behavior of cotton fibers. In this study, the tribological characteristics of cotton fibers and their relationship with the real contact behavior are investigated through reciprocating linear tribotesting and real contact analysis. Results show that the friction coefficient decreases with a general increase in load or velocity, and the load and velocity exhibit a co-influence on the friction coefficient. The dynamic change in the real contact area is recorded clearly during the experiments and corresponds to the fluctuations observed in the friction coefficient. Moreover, the friction coefficient is positively correlated with the real contact area based on a quantitative analysis of the evolution of friction behavior and the real contact area at different loads and velocities. This correlation is evident at low velocities and medium load.

scholarly journals A Simple Mechanistic Model for Friction of Rough Partially Lubricated Surfaces

2021 ◽  
Vol 69 (3) ◽  
Author(s):  
Gianluca Costagliola ◽  
Tobias Brink ◽  
Julie Richard ◽  
Christian Leppin ◽  
Aude Despois ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Friction Coefficient ◽  
Mechanistic Model ◽  
Applied Pressure ◽  
Real Contact Area ◽  
Experimental Measurements ◽  
Dynamic Friction ◽  
Real Contact ◽  
Dynamic Friction Coefficient ◽  
Direct Measurements

AbstractWe report experimental measurements of friction between an aluminum alloy sliding over steel with various lubricant densities. Using the topography scans of the surfaces as input, we calculate the real contact area using the boundary element method and the dynamic friction coefficient by means of a simple mechanistic model. Partial lubrication of the surfaces is accounted for by a random deposition model of oil droplets. Our approach reproduces the qualitative trends of a decrease of the macroscopic friction coefficient with applied pressure, due to a larger fraction of the micro-contacts being lubricated for larger loads. This approach relates direct measurements of surface topography to realistic distributions of lubricant, suggesting possible model extensions towards quantitative predictions.

An improved nonlinear model considering relative velocity for the friction behavior between untwisted glass-fiber tow and roller

2021 ◽  
pp. 004051752110308
Author(s):  
Yang Liu ◽  
Zhong Xiang ◽  
Xiangqin Zhou ◽  
Zhenyu Wu ◽  
Xudong Hu
Keyword(s):  
Friction Coefficient ◽  
Glass Fiber ◽  
Relative Velocity ◽  
Friction Model ◽  
Woven Fabric ◽  
Test Results ◽  
Application Process ◽  
Friction Behavior ◽  
Improved Model

Friction between the tow and tool surface normally happens during the tow production, fabric weaving, and application process and has an important influence on the quality of the woven fabric. Based on this fact, this paper studied the influence of tension and relative velocity on the three kinds of untwisted-glass-fiber tow-on-roller friction with a Capstan-based test setup. Furthermore, an improved nonlinear friction model taking both tension and velocity into account was proposed. According to statistical test results, firstly, the friction coefficient was found to be positively correlated with tension and relative velocity. Secondly, tension and velocity were complementary on the tow-on-roller friction behavior, with neither being superior to the other. Thirdly, an improved model was found to present well the nonlinear characteristics between friction coefficient and tension and velocity, and predicational results of the model were found to agree well with the observations from Capstan tests.

scholarly journals Comparison Between the Action of Nano-Oxides and Conventional EP Additives in Boundary Lubrication

Lubricants ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 54
Author(s):  
Valdicleide Silva Mello ◽  
Marinalva Ferreira Trajano ◽  
Ana Emilia Diniz Silva Guedes ◽  
Salete Martins Alves
Keyword(s):  
Friction Coefficient ◽  
Boundary Lubrication ◽  
Friction And Wear ◽  
Film Formation ◽  
Environmental Issues ◽  
Protective Film ◽  
Extreme Pressure ◽  
Extreme Pressure Additives ◽  
Environmental Requirements ◽  
Lubrication Conditions

Additives are essential in lubricant development, improving their performance by the formation of a protective film, thus reducing friction and wear. Some such additives are extreme pressure additives. However, due to environmental issues, their use has been questioned because their composition includes sulfur, chlorine, and phosphorus. Nanoparticles have been demonstrated to be a suitable substitute for those additives. This paper aims to make a comparison of the tribological performance of conventional EP additives and oxides nanoparticles (copper and zinc) under boundary lubrication conditions. The additives (nanoparticles, ZDDP, and sulfur) were added to mineral and synthetic oils. The lubricant tribological properties were analyzed in the tribometer HFRR (high frequency reciprocating rig), and during the test, the friction coefficient and percentual of film formation were measured. The wear was analyzed by scanning electron microscopy. The results showed that the conventional EP additives have a good performance owing to their anti-wear and small friction coefficient in both lubricant bases. The oxides nanoparticles, when used as additives, can reduce the friction more effectively than conventional additives, and displayed similar behavior to the extreme pressure additives. Thus, the oxide nanoparticles are more environmentally suitable, and they can replace EP additives adapting the lubricant to current environmental requirements.

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