APPLICATION REPORT | METALS
The extreme conditions include abrasive dust as well as heat.
Demag had supplied the cranes in 2002. Despite heavy use, these cranes had by no means reached the end of their lifecycle after 16 years. However, growing demand for SLR’s casting expertise required the use of ladles for handling up to 3t of molten material. Since the empty ladles themselves weigh more than 2t the existing cranes would then have exceeded their 5t load capacity. Demag has therefore replaced the
50.5-metre-long crane runway and installed two EKDE suspension cranes rated for foundry duty with a load capacity of 10t. The cranes are based on Demag’s universal crane range but numerous extra design features adapt them to the extreme requirements of foundry duty. The cranes transport ladles of molten
cast iron at a temperature of around 1500°C. The new cranes are designed for maximum availability: the drive is protected by heat shields and the crane bridge enclosure is installed exactly in the centre of the bridge because the heat is higher at the girder ends. The crane
bridge itself is exceptionally rigid to avoid deflection and extreme oscillation. For safety and redundancy, all four
trolleys of the travel unit are driven and equipped with a manual brake release function, which enables the crane also to operate with only two working drives. An automatic centrifugal emergency
brake serves as a catching device in the (unlikely) event that the drive unit in the hoist fails. The cranes are equipped with collision
protection and each is controlled by a Demag D3 radio control system. This ensures the operator can maintain a safe distance from the load. The DMR rope hoist has a bottom block with a hook as a load handling attachment and, like the entire crane, is designed for an ambient temperature of up to 55°C. An integrated weighing device, also suitable for high temperatures, shows the operators the weight of the filled ladles, which can weigh up to 8t. Other options are aimed at high availability in the not only hot, but also dusty environment. For example, there are self-adjusting brushes that continuously sweep the abrasive dust off the crane runways.
Only a relatively short period was
available to dismantle the old installation and install the new runways and crane; all this had to be done during the two-week factory break. The power supply also had to be renewed and structural changes made. After the end of the holiday, the foundry staff were able to work with the new cranes, which have since proven their worth under the demanding conditions. “It was important that the cranes run
smoothly from the start,” says Meisburger, “and they do. Finishing touches are being made gradually.” The finishing touches include modification of the tilting mechanism on the ladles. The hand wheels for manual operation can still be seen in the picture. SLR has now, however, switched the casting ladles to electric motorised tilting at the touch of a button as planned – for good reason. “The smaller crucibles were still easy
to operate manually,” says Meisburger. “With the new, larger crucibles, however, the operators would have to use the hand wheel to tilt 3 tons of molten material more than 80 times per shift. The electric tilting mechanism makes the work much easier and also improves safety.” ●
STREET CRANE DISTRIBUTES TATA STEEL
When steel has been cast and fabricated it needs to be distributed. Street Crane recently installed overhead cranes for Tata Steel’s distribution centre at Redcar in North Yorkshire. The centre provides steel and processing local customers. Plate and sections for use in engineering and marine fabrications or
structural steelwork can be cut, shot blasted and painted prior to delivery to customers ready for the next stage of manufacture. turnaround. Street supplied and installed four 12-ton
overhead travelling cranes of a radically
Street to handle the high rates of material speed of delivery. The cranes are of a double bridge design.
Two linked beams span the 20 metre bays; twin six ton hoists with magnets. This allows with transfer through the shot blast and is shipped out to customers.
The hoists on each crane can be operated singly or in tandem, to give additional stability for heavier or awkwardly-shaped loads. Anti-collision systems permit safe crane
movement on a common gantry: audible another crane approaching. Crane control is via a push button infra-red link, complying crane bridge platforms feature taut-wire safety lines and 10 safety harness anchor points at key locations such as panels, crabs and end carriages. To sustain uptime and all crane motions to assist with planning and proactive maintenance.
www.hoistmagazine.com | October 2022 | 39
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