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Resource Efficiency in Power Plant Construction

Bert Zorn, Managing Director of Schwarze-Robitec, on the subject of resource efficient tube bending technologies.

Producing companies spend the major part of the gross production value on material: According to calculations by the Federal Office of Statistics this is 45 percent on average. Subjects such as Sustainability and Green Technology have been discussed in the media for some years already. Nonetheless, the study by the Federal Office of Statistics shows that there is still a great savings potential in matters of sustainability. Producing companies could also lower their overheads by using green technologies. Anyone wanting to stay competitive, must handle resources particularly carefully in the face of rising costs for raw materials and energy, streamline production processes and thereby increase efficiency. The resource ‘man’ should also be taken into consideration comprehensively in this context because operator-friendly and safe production processes make a major contribution towards profitability of companies.

Maximum material utilization

The tube processing industry is particularly hit by rising raw material prices. In addition to the conventional purchase costs, additional costs, which are incurred during individual production steps in the form of material waste, are also a burden. For tubes in the power plant construction, the bending machine manufacturer Schwarze-Robitec from Cologne, has developed a controlled sawing facility, with which short bent parts can be produced effortlessly and streamlined from whole tube lengths. The sawing facility separates the processed tube from the residual piece already on the bending machine, whereby only a fine offcut results at the front and back end of the long tube which is not utilizable. A significant savings potential with regard to material is the dosing of lubricants. These counteract the high tribological loads on tool and work piece which occur during cold bending. With most lubricating methods, the lubricants are added in large quantities into the tube to be bent. To remove lubricants from the finished bent tubes after bending, the tubes normally need to undergo an elaborate cleaning, where further chemicals are used in the process. A considerably lower consumption is achieved with automatic lubricating systems. With the help of compressed air, they simply moisten the bending mandrel surface and tube inner wall. Through this optimal dosage, both the costs and the effort for the subsequent cleaning of tube and machine are considerably reduced. The micro-lubrication from Cologne’s bending specialist functions according to this principle: the lines for oil and compressed air run through the mandrel rod all the way to the mandrel. There, the oil is distributed by the compressed air. During the bending process it exits from the mandrel through small drilled holes. In this way the system combines a need-based lubrication with minimal lubricant consumption. Using resources sparingly means reducing not only the use of material but also of energy. Meaningful means are, for example, energy recovery modules or regulated hydraulic pumps, which drive bending tables via a separate pressure cycle.

The resource time

These days the processes in the producing industry must be faster, more cost-effective and more individualized. Saving a few seconds, even tenths of seconds, has a clear effect on the production efficiency. The resource time, together with the material input, plays a decisive role in production. The central question for machine builders therefore reads: At which points can technical improvements be undertaken to save time, in addition to material? If, for example, tube systems with two bending radii are to be manufactured, two different bending tools need to be used, which leads to further set-up times. To save these times, Schwarze-Robitec has developed the 1D/3D System especially for this, with which two different-sized bending radii can be manufactured within one tube serpentine. In this manner, set-up times can be reduced by up to 70 percent and at the same time the capacity utilization of the machine increased. Membrane tube wall machines, such as, for example, the FL Machine Series from Schwarze-Robitec are suitable for time-efficient manufacture of precisely bent tube walls in particularly large dimensions. With these, tube walls with a maximum width of 3,600 mm as well as a length of 25,000 mm and more can be processed particularly quickly.

Two bend heads for effective production

Not just in power plant operation can processes be designed cost efficiently through efficiency increase. Already when building power plants, lean production processes contribute considerably towards cost efficiency. That is why machines with two bend heads have established themselves for the production of tube lines because they enable time-optimized production of complex tube serpentines. Such a solution is the CNC 100 DB Twin from the tube bending machine manufacturer Schwarze-Robitec. It has two bend heads which can be moved vertically and horizontally (1 x left bending, 1x right bending) and bend the tube alternatively in clockwise and anti-clockwise direction. In this fashion, the machine offers high flexibility, for example when producing superheater serpentines. The tube serpentine doesn’t have to be turned after each bend, a fact which ensures quick and economic production processes and the manufacture of large side lengths. After the tube system has been finished on the twin head machine, it is transported to the Terminal-End-Bender with a gripper unit. This is another bending machine which conducts bends in both directions at the back end of the tube serpentine. Through this additional bending machine, bends are carried out subsequently in both directions at the back end of the manufactured tube serpentine, without having to interrupt the fully-automatic production process. This means that tubes with a length of up to 100 meters can be transformed into complete tube systems.

Designing production steps to make work easier

Another “time saver” are marking facilities which mark the positions on the tubes where welds or bypasses are to be carried out after bending. By this procedure, the facility takes the load off the operator. He now no longer has to conduct time-consuming calculations for subsequent determination of the corresponding points on the bent tube. For the effective and safe turning of flat tube serpentines, as they are required in the energy sector, the integration of a flip-over table presents itself as solution. Several pairs of arms are employed, whose fulcrum lies precisely in the tube axis. The tube is turned synchronously to the movement of the index head. Such expansions make work easier for the machine operator as an elaborate manual turning of the heavy and unwieldy tube serpentines is omitted.

From solutions for time efficiency and concepts for material savings all the way to extras which make work easier: All of these need to be taken into consideration when production processes are to be designed economically and sustainably. Therefore, this has not only a positive effect on productivity but also sustainably secures profitability. Last but not least, future-oriented companies can stand out from the competition through the use of corresponding technologies.

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