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Friction and Tools

  • T. Wanheim
  • N. Bay

Abstract

Friction on the interface between tools and specimen is of the utmost importance in all metal-working processes. The magnitude of the friction stress influences, to a high degree, deformation pattern, strain pattern, temperature rises, surface pressure on tools, and the total force in metal- forming.

Keywords

Friction Factor Friction Model Friction Stress Normal Stress Distribution Forward Slip 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notation

Aa

apparent area of contact

Ar

real area of contact

b

back pull factor

B

pre-strain, back pull

C

yield stress for unit strain

d0

initial hole diameter

d1

final hole diameter

D0

initial disk diameter

D1

final disk diameter

f

friction factor

F

function of β

G

function of β

h0

initial thickness

h1

final thickness

H

height of disk

HB

Brinell hardness

k

yield stress in pure shear

kf

shear stress in film

L

contact arc length

m

friction/shear yield stress ratio

M

torque

n

strain hardening exponent

N

normal force

p0

extrusion pressure at die entry

p

pressure, axial pressure

P

load

q

pressure, radial pressure

q’

pressure at limit of proportionality

r

reduction

R

roll radius

s

forward slip, punch displacement, sliding length

S

force on die support

T

tangential force

v1

exit velocity

vR

roll velocity

z0

axial length of die

z

distance from die opening

α

ratio between real and apparent area of contact

β

semi die angle

δ

angle between axis of symmetry and larger principal stress

ε

average effective strain

μ

coefficient of friction

σ0

equivalent yield stress

τn

nominal friction stress

τ’n

nominal friction stress at limit of proportionality

φN

neutral angle

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Copyright information

© Elsevier Applied Science Publishers LTD 1986

Authors and Affiliations

  • T. Wanheim
    • 1
  • N. Bay
    • 1
  1. 1.Department of Mechanical TechnologyTechnical University of DenmarkLyngbyDenmark

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