Load handling during the construction of concrete elements

At its site in Hamm (Westphalia), GOLDBECK manufactures concrete elements for the construction of logistics and industrial facilities, office and school buildings, multi-storey car parks and residential buildings. In the newly built production area, foundation cages and reinforcement steel mats are manufactured and made suitable for the subsequent casting of concrete components. Efficient transport of wire coils, reinforcing bars and bulky components between the production areas is carried out by several Demag cranes and supported by assistance and convenience features of the Demag smart SafeControl system.

Customer

The GOLDBECK company and its products can be found everywhere. The construction and service company has almost 80 branches throughout Europe. In over 50 years of its history, GOLDBECK has built around 10,000 turnkey commercial properties for its customers. Its special feature: the company has a system for planning and building. Major construction elements are industrially prefabricated in ten of the company’s own plants and then delivered directly to the construction site and assembled there.

The GOLDBECK plant in Hamm (Westphalia), which opened in 2009, specialises in the production of ceilings, columns, foundations and external wall elements. Only last year, the location was expanded by a total of 8,200 square metres of production space. The system elements are, of course, supplied from the company’s own factory. A winning system.

Requirement

The material flow process begins with the delivery of wire coils and reinforcing bars. These raw materials are processed along two material flows and in various steps, combined with other components and then transported to the next production section, where they are refined into finished concrete elements.

It starts with steel

At the beginning of the material flow, the raw materials are delivered by truck. The wire coils are delivered to bays 11 and 12, reinforcing bars to bay 10. The production line in bay 10 manufactures the reinforcing bar support for casting the concrete for concrete pillars or foundation cages. Cranes are needed in this step to transport long goods and for precisely serving a cutting machine.

Large-volume steel mats

The so-called drawing mats are produced in bays 11 and 12. Later in the production process, these form the structure of wall elements in all sizes. The tasks of the cranes are to unload the wire coils from trucks and feed the production line where the coils are automatically cut to length and welded into steel mats. The cranes then transport the mats in bundles to the next step, where they are linked together to form reinforcement cages. For special requirements, a working area is set up at the end of bay 12 for manual improvement of the reinforcement mats. The customer’s requirements are thus clearly defined. For the intralogistics process within the new production section, a solution is needed for safe handling of the sometimes bulky reinforcement mats and long reinforcing bars. Precise feeding of the machines is essential, as is the specially secured transport of long goods between the workplaces. Permanent availability of the cranes for different crane operators needs to be achieved by means of radio controls.

Solution

The crane concept from Demag impressed GOLDBECK. Seven EKKE single-girder overhead travelling cranes with a load capacity of 3.2 to 10 t and a ZKKE double-girder overhead travelling crane with a load capacity of two times 3.2 t transport the goods within the new production section. On the crane runway in bay 10, two overhead travelling cranes travel in smart tandem. Handling of the extremely long bundles of reinforcing bars requires two cranes working perfectly together for safe and reliable transport.

The crane fleet is completed by two single-girder cranes in bay 11 as well as a single-girder crane and the double-girder crane in bay 12. All indoor cranes are equipped with the Demag DMR modular rope hoist. Some of the DMR’s many options were used to meet the needs of the workplaces. Special trolley mounting positions, assistance and convenience features or control options make daily material handling easier. All lifting and travel axes of the cranes have infinitely variable control. This results in improved ease of operation for the employees.

Short interview with Mr Steffen Fester, Production Manager, Goldbeck Betonelemente GmbH in Hamm, Germany

Demag: Mr Fester, why did you prefer the Demag solution?

Steffen Fester: We were searching for a holistic solution for the approximately 8,200 m² production area, with a focus on reinforcement production, and Demag offered a customised solution for us. With our focus on synchronised production with recurring components, modern crane installations provide the foundation. In addition to the large span with low headroom dimension, the high speeds of all motion axes as well as reliability were decisive factors for us. Positive experiences from previous business as well as fair pricing led to the final decision.

Demag: What are the advantages of using Demag products?

Steffen Fester: The assembly time of the installations was extremely short; most of the cranes were ready for test operation after only a few days. They helped us directly with the installation of the production machines. After the installation was complete, the after-sales service was always reliable. So far, there have been no extended downtimes. All eight cranes can be installed in any bay, so production will remain flexible in the future as our product portfolio adapts to the market.

Demag: What feedback have the employees given you so far?

Steffen Fester: Of course, our employees are thrilled when they first see a new crane installation. The individual benefits then became apparent at second glance. The high speeds of all three motion axes are an enormous advantage. Within the processes, we rarely talk about crane operating times. These are already well optimised. Digital load displays help enormously with fast checking of coil and bar deliveries. They also help with small inventories or loading. The tandem function in bay 10, which is mainly used for steel bars up to 18 metres, enables safe handling with only one control system. With our clearance of 12 metres between the supports, it was not easy to provide the tandem function with two cranes with a hook centre distance of only six metres. The optical anti-collision system has so far done what it is supposed to do. Here, the static design from GOLDBECK and the Demag crane installation worked well together.

Precisely meeting requirements

The new production bay was designed from the outset with a well thought-out and, where necessary, flexible crane concept. The optimised design of the installations starts with the uniform track gauge of 24 metres. The clearance, measured from the ceiling strut to the top edge of the crane rail, is always 1.24 metres. The structural height of the trolleys has thus been reduced and the design optimised. These uniform dimensions make it possible for the customer to respond to changing requirements within the production line at any time. This even means that the cranes can be relocated, as needed.

To conform to the structural specifications of the building, the wheel base was increased from the standard 3.15 metres to 4 metres. This adaptation made it possible to dispense with some support columns and create more free space for intralogistics processes during the planning phase for the new production area. With section lengths of 12 metres, there are positive aspects with regard to dimensioning the crane runway and thus a cost saving, as the cranes fit exactly into the building concept. Optimised long travel is achieved by horizontal rollers on both sides, which guide the crane long-travel units close to the crane runway girder. These guide rollers reduce skewing forces and provide noticeably smoother travel characteristics. This means an increase in efficiency and working time, especially when transporting components between workplaces.

The flexibility of the DMR generation of rope hoists is also evident in special solutions. The special width of the reinforcement mats (dimensions: 3.5 x 9 m) would have made them impossible to grip if the two rope hoists had been installed in the usual mounting position between the crane girders. The choice of mounting position on the outside of each unit achieved the desired result. With the larger hook centre distance, the trolley with two DMR rope hoists can grip the reinforcement mats without significantly having to increase the crane approach dimension.

Safe, by Demag

Care must always be taken when transporting goods. Inattention and unpredictability can lead to dangerous situations and quickly end in a workplace accident. This is why it is important that the employees’ workplace is also safe while the crane is in operation. The added convenience is a further advantage.

The Demag DMR modular rope hoist enables mechanical and electrical assistance features to be integrated. Frequency-regulated control of the cranes plays an important role in ease of use. Start-up and acceleration are infinitely variable, so that the operator can carry out long-, cross-travel or lifting motions with the highest degree of precision. As the pressure on the control element of the radio control is increased, the corresponding motion axis increases in speed. And, of course, this also applies in the opposite direction, so that the movements of the crane can be controlled with absolute precision and ease. Positioning of reinforcement mats and reinforcing bars in the intralogistics process is thus made easier, more efficient and saves working time.

Smart tandem

The smart SafeControl system provides improved safety when using the crane. For the transport of long goods in bay 10, GOLDBECK relies on the smart-tandem convenience and assistance feature. Two cranes can be electrically coupled and operated from a common control unit. This is done easily by the crane operator as smart tandem mode can be switched on and off via a selector switch. The operator can always see the function on the display of their DRC radio control system and on the large display of the Demag StatusBoard on the crane girder. In addition, the StatusBoard visualises the current operating statuses of the crane in real time. These include, for example, load capacity, total load, overload, service or the activated assistance and convenience features of the SafeControl system – for transparent and, above all, safe control of the crane.

Electronic collision protection

All cranes are equipped with an optical crane anti-collision system, so that even less experienced crane operators are supported and the cranes cannot collide with each other. Dual laser sensors redundantly measure the distance between the respective cranes on the crane runways. If predefined distances are exceeded, the crane is switched off in two stages. In the first stage, the crane can only be moved at slow speed. In the second stage, the crane is safely switched off. This concept of independent safety shutdown with dual-channel hardware corresponds to safety category 3 to EN 13849-1. Long-travel limit switches in two-stage design avoid load sway, which can be a danger to life and limb and a risk of damage to machinery. The long-travel motion changes to slow speed at the first limit switch and the drives are completely switched off shortly before the end stops are reached.

If the crane operator activates the tandem function in bay 10, the distance maintained between the cranes is automatically overridden and the cranes can be moved closer together. However, this is only possible if the total rated load of the two cranes is below the specified limit of 10 t. Demag SafeControl provides electronic protection by load summation.

Electronic calculation of the total load in bay 12

The ZKKE double-girder crane in bay 12 also uses this function so that the individual loads of the two hoists are calculated electronically and protected against overload by load summation. An overload of the crane bridge is thus avoided by automatic shutdown if the total load capacity on the hoists is exceeded.

Workplace cranes in cage production

The cage production area was equipped with workplace cranes and chain hoists. Thanks to the Demag DC-Pro chain hoists, the three KBK steel jibs lift the individual coil steel bars into the production area, where they are then hardened to form steel cages.
At each of three workplaces, two DC-Pro chain hoists lift and lower a steel spreader from which the cages are suspended, and work can be done on the cages at an ergonomic height.

Technology

The smart SafeControl system provides the greatest possible safety during crane operation. The long-travel limit switches and safety control system support the crane operator, helping to avoid any accidental damage in the crane’s working environment. In smart tandem mode, two cranes with up to four trolleys can be used to transport particularly bulky and heavy loads. Switching between single-crane and tandem mode is quick and easy with a selector switch on the radio control.

Three questions for Uwe Steinke, Sales Engineer responsible for the GOLDBECK Betonelemente GmbH project in Hamm (Germany)

Demag: Which information is needed from the customer for a first enquiry?

Uwe Steinke: Basically, this is always developed in the initial discussion with our customer. In the case of GOLDBECK, the customer already approached us in the first enquiry with a very good and precise idea of what the cranes would have to do. At an on-site meeting, we were able to discuss further requirements that will help the customer with their long-term handling needs and develop a precisely planned crane concept for many years. 

Demag: Which product features are worth a special mention at GOLDBECK Betonelemente?

Uwe Steinke: Well, we have uniform dimensions for the interface between the workshop and the cranes. This means that all of the workshop dimensions, the crane rail and the track gauge were selected so that the cranes can be used in all of the workshops, if necessary. In addition, all of the cranes have a special wheel base of 4 metres, which enables us to meet the static design requirements. The double-girder crane in workshop 12 is a special design. On the one hand, it has a trolley that is tailored for handling the reinforcement mats. Our ZKKE has two hoist units on the trolley with an exact hook centre distance of 4 metres in the long-travel direction. This enables both hoist units, which each have a load capacity of 3.2 tons, to pick up mats which measure 3.5 x 9 metres. 

On the other hand, the hoists are suspended from the trolley frame in such a way that the crane headroom dimension is kept as low as possible. The dimensions of the crane determine the headroom dimension for all three workshops – and also affect the requirement for all cranes to be able to operate in every workshop. This also made it possible to reduce the necessary workshop heights and, therefore, the costs. In combination with the design of the crane girder, an optimum compromise was found between the crane headroom dimension and the maximum possible lifting height.

Demag: Which customer requirement made this project particularly interesting? 

Uwe Steinke: Above all, I consider that to be the assistance and convenience features. First, cranes 10.1 and 10.2 in workshop 10 have a function which ensures that a certain distance is maintained between them for static design reasons. Regardless of the load, the long-travel motion is switched off when the specified distance is reached. When the operator activates the tandem function, the distance maintained between the cranes is automatically overridden and the cranes can be moved closer together. However, this is only possible if the total rated load of the two cranes, which is determined by load summation, is below the specified limit value of 10 tonnes. This means that the employee has electronic back-up when the cranes are in operation and can concentrate fully on handling the long material. All three motion axes of the cranes are completely controlled by frequency inverters. The lifting speeds were selected and adjusted depending on the customer’s intended task for each crane.

The DRC-10 radio control system enables operators to control the crane intuitively and ergonomically. Current operating statuses of the crane are shown on the LCD display. The battery integrated in the hand-held transmitter can be fully charged within just 2.5 hours and can be used for uninterrupted operation for up to 5 days. Up to three transmitters can be paired with one crane. They can be switched at the press of a button without disrupting the operating process. Control of individual cranes can thus be easily handed over from employee to employee. Transmitters can be switched in a matter of seconds. As part of the “Revolving Warranty”, any defective components are repaired or replaced free of charge by the Service department at their discretion. In this way, safe operation of the cranes can be ensured beyond the statutory warranty at calculable costs.