Tribological Size Effects in Sheet Metal Forming Measured by a Strip Drawing Test

Vollertsen, Frank; Hu, Zhenbang

doi:10.1016/s0007-8506(07)60419-3

Cited by 103 publications

(64 citation statements)

References 3 publications

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“…While the maximum point of the curve FEM-50 is about 8% lower than that of EXP-50. The reason for this might be the assumption in the calculation model: The normal pressure at the radius is uniform [1]. However, the simulation shows two local contact zones, see figure 6.…”

Section: Scaled Strip Drawing Testsmentioning

confidence: 95%

“…This causes the so called size effects, i.e. the occurrence of unexpected results concerning the forming force of the forming limit [1]. Since deep drawing is essentially affected by the friction between the work piece and tools [2,3], which is also affected by the size effects [4,5], the tribological size effects in sheet metal forming were investigated in our former work [6,7] and the sizedependent friction functions were acquired.…”

Section: Introductionmentioning

confidence: 99%

“…

ABSTRACT: In this paper a size dependent FEM-simulation for sheet metal forming was realized applying the size dependent friction functions acquired from strip drawing tests [1]. The software ABAQUS 6.6.3 was used to simulate the strip drawing tests and deep drawing process in different process dimensions.

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confidence: 99%

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Modelling of friction with respect to size effects

Vollertsen

2008

Int J Mater Form

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In this paper a size dependent FEM-simulation for sheet metal forming was realized applying the size dependent friction functions acquired from strip drawing tests [1]. The software ABAQUS 6.6.3 was used to simulate the strip drawing tests and deep drawing process in different process dimensions. A 2-dimensional model was built for strip drawing test and a 3-dimensional model was built for deep drawing process. Both processes were experimentally carried out in different dimensions. A constant friction coefficient as well as a friction function, which shows a dependence of friction coefficient on the contact pressure, was applied in the simulation. The simulated punch force vs. punch travel curves were then compared with the experimental curves. A discussion about the difference between these curves with consideration of tribological size effects will be given.

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Section: Scaled Strip Drawing Testsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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Modelling of friction with respect to size effects

Vollertsen

2008

Int J Mater Form

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“…In opposite manner a larger drawing radius reduces the width of high pressure forming area, more lubricant pockets are open and the friction increase due to less surface separation. In comparison to macro scale the overall higher friction in micro deep drawing is a result of the geometrical size effect [11]. The roughness of contact surface is not scaled down by the specimen size.…”

Section: Matec Web Of Conferencesmentioning

confidence: 96%

Influence of tribology size effect on Stribeck curve in micro deep drawing

Tetzel

2015

MATEC Web of Conferences

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Abstract. The lubricant viscosity is one parameter for optimizing drawing processes. The influence is due to the velocity depending friction behaviour between work piece and tool, as well as the effective process forces and resulting pressures in the lubricant. Because of the tribological size effect, the knowledge gained in macro processes cannot be transferred directly to micro forming processes. To understand the influence of the drawing speed, several parameters as the drawing radius and viscosity of lubricants are varied in this work. The resulting Stribeck curves show a varying effect of the different kinematic viscosities. High viscosity lubricant reduces the occurring friction significantly at low Stribeck numbers, but increases friction with rising Stribeck number extremely. Concluding the results, it can be stated that the hydrodynamic friction demands a relevant portion of the overall friction in micro forming process especially at high drawing velocities, which cannot be explained by the lubricant pocket model.

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“…Fleck and Johnson [4,5] suggested that the roll deformed to a non-circular profile and a neutral region of no-slip existed in the roll bite for finite reductions of the strip, and plastic reduction occurred near the rolling entry and rolling exit zones. For scale-down size effect, Vollertsen and Hu [6] analysed tribological size effects in sheet metal forming. An open and closed pockets theory has been proposed to analyse this scaled down effect on material surface deformation behaviour in micro forming process [7].…”

Section: Introductionmentioning

confidence: 99%

Lubrication characterisation analysis of stainless steel foil during micro rolling

Xie

Manabe

Tada

et al. 2015

Int J Adv Manuf Technol

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Physical parameters, such as microscopic and roughness, play important roles in microforming process due to an increasing ratio of surface to volume of the deformed material. The study on lubrication characterisation in microforming is getting more attractive to researchers because traditional models are not reliable in this scaled down process. In this study, the micro rolling deformation characterisation has been investigated on SUS 304 stainless steel considering lubricant effect and feature size effect. The foil thickness plays an important role in the tribological features of micro rolling. The evolutions of both oil film thickness and foil surface are analysed accordingly. All the results have been verified experimentally via the new developed 2-Hi desktop micro rolling mills. Abstract Physical parameters, such as microscopic and roughness, play important roles in micro forming process due to an increasing ratio of surface to volume of the deformed material. The study on lubrication characterisation in micro forming is getting more attractive for researchers because traditional models are not reliable in this scaled down process. In this study, the micro rolling deformation characterisation has been investigated on SUS 304 stainless steel considering lubricant effect and feature size effect. The foil thickness plays an important role in the tribological features of micro rolling. The evolutions of both oil film thickness and foil surface are analysed accordingly. All the results have been verified experimentally via the new developed 2-Hi desktop micro rolling mills.

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Tribological Size Effects in Sheet Metal Forming Measured by a Strip Drawing Test

Cited by 103 publications

References 3 publications

Modelling of friction with respect to size effects

Modelling of friction with respect to size effects

Influence of tribology size effect on Stribeck curve in micro deep drawing

Lubrication characterisation analysis of stainless steel foil during micro rolling

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