XXL process crane with 500 ton capacity featuring igus energy chains

The Kranbau Kšthen GmbH has built a process crane featuring
a lifting capacity of 500 tons, with the weight distribution in two axes finely
balanced by means of a special shaft end support. The signal and energy
transmission takes place via energy chains and cables from igus.

‘Anything but standard’: this describes the
development and production programme of Kranbau Kšthen GmbH in a nutshell. The
company, engaged in crane manufacturing since 1934, specialises in
sophisticated process cranes that are closely integrated into production
systems. Example applications of these cranes are in the steel industry, for
which Kranbau Kšthen builds slab, charging and foundry cranes. In this field of
application, the company has further reinforced its indelible footprint since
it was incorporated in the Georgsmarienhütte-Holding (GMH) in 1998, and thus
into a leading steel group.

Requirement:
500 tons of well-balanced load

The cranes often work under adverse environmental
conditions such as heat, dirt, and high mechanical stresses. In this regard, a
recently built process crane is not required, but the needs are really unusual
and extreme in many respects. It is used in an ABB plant in Sweden, which
manufactures large transformers. And ‘large’ here means really massive: while
the predecessor type series weighed a maximum of 300 tons, the new
transformers, which offer higher performance and improved efficiency, weigh up to
500 tons.

This weight increase required the investment in a new
process crane, and the Kranbau Kšthen GmbH was commissioned for its development
and production. A special feature had to be taken into account: the centre of
gravity of the transformers is distributed very unequally. The crane must adapt
accordingly and always ensure a smooth and sensitive lifting and lowering of
the heavy load.

Flexibly
adjustable and rotatable heavy-duty shaft end support

Based on these specifications, the Kranbau Kšthen
engineers developed a process crane with a lifting capacity of 500 tons and a
special heavy-duty shaft end support. It consists of two carriers whose spacing
is changed by lead screws. The two attachment points on each carrier are also
adjustable so that each of the four winches can be positioned separately. The
transformer can therefore always be attached in such a way that the weight (up
to 500 tons) is evenly distributed over all four attachment points. In
addition, the entire shaft end support is rotatable. It is suspended on a
load-measuring bolt of impressive dimensions.

A ‘clean’
crane

In addition to its extremely high load-bearing
capacity, the crane itself also has some special features. These include three
auxiliary strokes, each with a loading capacity of 20 tons, and an extraction
system on the trolley travelling winch. The reason for this is that if
impurities get into the large transformer during the assembly process, this can
have serious consequences for its function. For this reason, ABB produces these
plants in a very clean environment and demands that the crane does not generate
any abrasion during operation.

Energy
chain with strain relief and floating moving end

Cable must be guided on the crane girder to the
30-metre-wide bridge; here a standard energy chain from the E4 4040HD series in
the igus product range is used. This type of chain has proven itself worldwide
in crane technology. Due to the special design of the chain links with undercut
design, the chain is able to absorb high push-pull forces and also provides
very good strength to absorb lateral forces. And the material of the energy
chain – igumid G with an ‘HD’ design – ensures optimised sliding properties
and, as desired, a very long service life with low abrasion.

The design of energy chains follows a standard process
at Kranbau Kšthen. Dipl.-Ing (FH) Tom Kuhnt, in charge of electrical projects:
“We use a form that contains all the necessary information such as
specifications, installation situation and options. This allows igus to design the
chain quickly and reliably.” In this case, the extras included a double
strain relief and a floating moving end, which compensates for any lateral
misalignment and wheel clearance in the trolley drive. Kranbau Kšthen has
already had good experiences with this system in other projects.

Chain
plus cables: The advantages of the system

There was also good experience with the purchase of
chain and cables from a single source, which is igus. Tom Kuhnt: “From our
point of view, it has proven to be a complete system, which is designed
precisely for the individual conditions.” Here the collaboration with igus
has been well established. The chainflex cables were developed specifically for
use in mobile systems. Due to the favourable environmental conditions (normal
climate window, no high travel speed), cables with PVC outer jacket can be used
in the ABB process crane. They are more cost-effective than TPE cables and also
generate less abrasion than PUR jackets (ensuring cleanliness).

The electrical connection between the two shaft end
supports, which can be moved towards each other, is also ensured with energy
chains and chainflex cables from igus. The E4 series e-chains are also used
here. The undercut design provides firm grip in lateral acceleration and
inclination of the shaft end support. An integrated brake offers very smooth
running.

At the rotating joint of the shaft end support, an
enclosed triflex R energy chain with twistable cables from the chainflex
product range ensures mobility in the rotary axis. This chain was originally
developed by igus for robotics. In the process crane, it is virtually
unchallenged in terms of dynamics, but protects the cables reliably in the
rotary movement.

Sophisticated
acceptance tests

Before a crane leaves the site of Kranbau Kšthen, a
factory acceptance test takes place. Here, the crane is fully evaluated and
tested jointly with the customer. This elaborate test is a standard procedure
at Kšthen and shortens the commissioning time of the crane system at the
customer.

Subsequently, the crane was distributed over several
flat bed vehicles and transported to Sweden. Part of the route was by sea, so
ferry loading of the fragile cargo was inevitable.

Kranbau Kšthen received support for the project from
its local sales and service partner Svenska Lyft AB. The company, which has a
high level of expertise in crane electronics and works regularly with the
Swedish igus subsidiary, will be in charge of the crane’s service in the
future.

The test and final inspection of the process crane at
ABB also posed special challenges to those in charge; 625 tons of test weight
(corresponding to 125 percent of the maximum nominal load) had to be provided
for the acceptance test. Tests of the emergency stop device at full speed were
also part of the test series. At the customer’s, the acceptance was carried out
thoroughly. Maik Stern, Head of Production at Kranbau Kšthen: “After all,
as a globally leading technology company, ABB is also a specialist in the field
of crane technology and therefore also a critical and competent customer.”

The high quality igus energy chains and cables are
available from Treotham Automation. Treotham are also able to service cranes in
Australia and New Zealand as well as recommend special solutions for users.

For more information, please visit the Treotham
Automation website www.treotham.com.au or call 1300 65 75 64. 

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