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The development of a process for the radius hardening of diesel engine crankshaft journals

Thesis (M. Diploma (Mechanical Engineering))--Cape Technikon, 1992. / Radius hardening on journals of forged steel Diesel
engine crankshafts is performed in order to increase
fatigue life characteristics. This requirement may
be necessary if the demands for engine power are to
be increased, but where the existing crankshaft
design is close to its fatigue limit, such that an
increase in loading will cause it to'fail.
Induction hardening of journal radii changes the
make-up of the material from a coarse to a fine
crystalline structure which alters the features of
crack propagation. As a consequence of this higher
loads can be applied onto the crankshaft without
ultimately resulting in catastrophic material
failure. Extending the induction hardened zone from
the bearing surfaces into the radii of journals,
culminates in process difficulties which are not
experienced in non-radius hardened
Hardening of journal radii induces
as well as
releases stresses in the crankshaft webs. This
results in a deformation of the crankshaft which can
be measured in the form of journal runout. Such a
problem cannot be overcome by straightening the
crankshafts in order to reduce runout, since this
will cause
hand induces
the radii to crack once hardened.
in the unhardened state on the other
stresses which will be released again
after hardening. This results in an increase in
runout. High runout indicates that stresses have
been induced into the crankshaft material. This is
undesirable since this will make critical
manufacturing processes such as grinding, governing
of journal lengths, uncontrollable. It can furthermore
result in creep of the crankshaft long
after the manufacturing date. This results in
crankshaft deformation, noticeable through an
increase in runout. Since the crankshaft cannot be
straightened after hardening, the consequence is
that it will be unusable. The process must
therefore be developed in such a manner, that all
variables which can contribute towards stress
induction resulting in journal 'runout, must be
investigated and resolved.
Date January 1992
CreatorsKlos, Gerhard P. J.
ContributorsVan der Schyff, T.
PublisherCape Technikon
Source SetsSouth African National ETD Portal
Detected LanguageEnglish

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