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Technology News
www.read-tpt.comJ
uly
2014
71
Wear resistant chains for the
steel industry
INCREASING demands on the
availability and wear resistance of
chains in various applications of the
steel industry require modern concepts
in the design and realisation of the
employed products.
Corresponding solutions and products
are being offered by KettenWulf Betriebs
GmbH.
The company’s product range of
conveyor and drive chains covers
applications from pig iron preparation,
steel production and onward processing
up to the transport of the finished
products.
Requirements on availability and
wear resistance are the key points
for KettenWulf’s concept of efficient
products under consideration of the cost
structure. Besides the fatigue strength,
the wear resistance in the chain joint
plays a major role in the life time cycle
of a chain.
The consideration of the geometry
of the individual chain components –
dimensioning of link plates, bushes, pins
and rollers – as well as the adherence to
bearing pressure limits between bushes
and pins, bushes and rollers and to the
bearing stress at the sidebar pitch holes
are basic requirements.
While the breaking load and the
fatigue strength are mainly determined
by the geometry and the strength values
of the link plates and pins, the wear
resistance of a chain is influenced by
a combination of geometry, grade of
materials, heat treatment and a final
surface finishing of the individual chain
joint components.
The material selection is the crucial
factor for a successful chain concept.
Besides the classic carbon steel C15,
a number of alloyed and high alloyed
case hardened steels, heat treatable
steels with different alloying additions or
fine-grained steels may be considered
depending on the profile of the existing
technical requirement.
An additional heat treatment is a
further step towards a highly wear
resistant surface. Depending on the
material grades, heat treatments of
the product such as quenching and
tempering, case hardening or induction
hardening are carried out in KettenWulf’s
own heat treatment facility.
Along with a ductile core structure,
a highly wear-resistant surface with a
hardness of HRC 56-62 with depths of
0.6-6mm is achieved at a core strength
of up to 1,200N/mm².
When used in the warm area the
reduction of the surface hardness in
dependence on the ambient temperature
and the chain temperature needs to be
considered.
A change of the geometry of the
individual components may compensate
such reductions.
The final finishing process of the
surface and the manual initial lubrication
of the chain joints produce an additional
constant against premature wear.
To ensure a homogeneous chain
concept, the fatigue strength and the
breaking load have to be considered
besides the wear resistance.
The selection of the material grade
and the production of the pitch holes are
of vital importance for the reliability of a
chain.
Besides a quality steel having a tensile
strength of minimum 700N/mm² there is
a wide selection of very efficient heat
treatable and fine-grained steels that
may be used, including an additional
heat treatment of the basic material
depending on the chain application.
The evaluation of different shapes
of pitch holes for reduction of stress
concentration at respective surface
qualities has led to a maximum bearing
contact area of the press fitment
between pin and chain link plate forming
a further contribution to a fatigue
resistant connection respectively a
successful chain execution.
To ensure the homogeneity of two or
multiple chain strands running parallel to
each other, the individual chain strands
may be matched and marked according
to the length measurement results of
each individual strand in addition to the
wall thickness deviation measurement
of each bush.
A well-balanced concept under
consideration of all chain and conveying
equipment parameters contribute to
operational safety and corresponding
operational lifetime.
KettenWulf Betriebs GmbH
– Germany
Fax: +49 2973 801 2296
Email:
service@kettenwulf.comWebsite:
www.kettenwulf.com