2 - ALU-WEB.DE

More documents

Recommendations

Info

10 MACHINING 4 | 12-2009 APT ALUMINIUM NEWS Sophisticated aluminium supporting structure for gigantic jewel Industrial service provider turns architectural vision into reality It is often a long and thorny journey from a design on a computer screen to its actual realisation. This applies all the more the greater the dimensions. There is a need for service providers who take overall responsibility for the implementation and deal with every aspect from material procurement through to the supply of components ready for installation. “The Makkah Clock adds the crowning finish to an extremely sophisticated skyscraper project in Islam’s most important place of pilgrimage,” explains Martin Meenen, CEO of Aquatec GmbH based in Emmerich, Germany. The company started life as a job shop specialising in the waterjet cutting of large format parts. It now operates two of the largest waterjet cutting units in Europe, with table sizes of 16,000 x 4,000 mm, and has developed uncompromisingly into an all-round Graphics: Aquatec The ‘Jewel’ located on top of the Makkah Clock at a height of about 500 m is a sophisticated structure made of glass and aluminium service provider, offering its clients practically every desirable additional service – from the procurement of material via the selection of suitable processing steps through to implementation and supply of ready-to-install parts as a complete package. A current example of this is the company’s contribution to the ‘jewel’ above the clock at the top of the 500 m high building that together with four other skyscrapers will dominate the skyline of this Saudi Arabian city. The top part, the design of which is based on a precious stone, is 29 m high and consists of a total of eight aluminium and glass segments each up to 10 m wide. The desired faceting As a specialist for large-format waterjet cutting, Aquatec has two of Europe’s largest waterjet cutting machines with table sizes of 16,000 x 4,000 mm of the exterior is achieved via a complex, intricate, threedimensional latticework of aluminium nodes and crosspieces to which the massive panes of glass, almost 80 mm thick, are bonded directly. This thickness is required in order to withstand the enormous wind loading: at this height, the desert wind often Each of the numerous triangular surfaces is bordered by up to 6 m long aluminium mullions that are joined together (lower left) with the help of complex node elements reaches hurricane force. Nevertheless, the widths of the webs between the huge plates of glass that are visible from the outside are only about 20 mm wide so as not to impair the overall aesthetic appearance. Even the material requirements are extremely demanding … “The vision is always to the fore in such projects,” explains Mr Meenen. “It is essential to create something distinctive that has never been built before. The demands are correspondingly high.” This forces both architects and their engineering teams to take their conceptual designs into areas where others have previously not dared to tread. This pressure is in turn passed on to the service providers carrying out the work, who then have to go searching for materials, production processes and special solutions that are not available on the market, or at least not in the required form. This starts with material procurement because as a result of the extremely high loading the combinations of material and strength required for the nodes and crosspieces, which were hitherto not available from any manufacturer. For example, the AlSi1MgMn T6 blanks for the massive nodes were cut from round stock with diameters between 400- 650 mm and had to have a proof strength of 230 MPa in the interior even though the manufacturers of such material thicknesses usually only guarantee 180-200 MPa. It was not possible to revert to another material, in part for technical reasons such as corrosion resistance, anodisability and the like, and in part for cost reasons. The search for a producer who was willing to guarantee the specified requirements proved to be complex and required intensive negotiations. The procurement of the raw material for the crosspieces proved to be equally problematic; these were made Martin Meenen: “Our job is to turn our customer’s concept into reality. We take overall responsibility for that.” from rolled plate of the naturally ageing alloy AlMg4.5Mn with a wall thickness of 82 mm and had to have a minimum proof strength of 155 MPa. Here, too, it was only after a long search that one was able to find a producer who could guarantee this value instead of the usual 115-125 MPa – thanks to a specially designed thermo-mechanical treatment. Machining: extremely demanding, exceedingly long “Having solved the material procurement problem we were still far from solving all the problems because to some The 82-mm thick AlMg4.5 Mn rolled plate for the mullions. A special thermo-mechanical treatment was devised in order to guarantee a proof strength of 155 MPa all Photos: Klaus Vollrath The production-related challenges included milling of deep pockets with a tool that was 250 mm long but could only have a maximum diameter of 16 mm extent we had to break new ground in the processing,” Mr Meenen recalls. This began with the minimal machining tolerances of only 2 mm all around the mullions, and this despite the fact that they were up to 6,000 mm long. One of the reasons for choosing these exceptionally low values was that the wall thickness was a critical factor in ensuring the necessary mechanical properties. The consequence was extremely tight tolerances for distortion of the blanks to be processed. This proved to be a challenge even when it came to choosing a suitable machine for the five-axis processing of these parts and the necessary special milling cutters. In the end, this was only made possible by special modification of a Chiron machine tool by lowering the machine bed. The machine was equipped with two identical swivelling tables that could be synchronised in such a way using the machine controls that it was possible to machine individual workpieces having excess length. With shorter components, the two tables could be used for different jobs independently of each other. As an alternative for future use, the machine can be optionally equipped with a loading door on the side thus making it capable of accommodating workpieces up to 13,000 m long. An added challenge was the development of suitable technologies for machining the cut-outs, which in some cases were extremely deep, especially in the area of the locking devices at the end of the crosspieces. Here, tools and machining strategies had to be found that enabled the machining tolerances to be adhered to even using extremely thin and long milling cutters. The required radii of only 8 mm limited the diameter of the milling tool to a maximum of 16 mm – and that at immersion depths of up to 250 mm. Waterjet cutting as core competence “The benefits of using a waterjet manifested themselves fully even as soon as we cut the individual mullions out of the rolled slab,” explains Mr Meenen. With a thermal process, such as laser-beam cutting, large machining allowances would have had to have been used in order to eliminate microstructural damage by completely removing the heat-affected zone, which would have resulted in correspondingly higher costs. In addition, the kerf in waterjet cutting is significantly narrower than with a saw cut, which allows more blanks AlSi1MgMn T6 blanks with diameters from 400-650 mm, which also had to have a proof strength of 230 MPa in the interior, were used for the nodes
APT ALUMINIUM NEWS 4 | 12-2009 EQUIPMENT For the five-axis finishing of the nodes, tools had to be used that were sometimes very small to be cut out of a rolled slab of a given width. An added advantage is the possibility to also cut at an angle, which was necessary with some of the mullions. With conventional saws, this would have been impossible or only possible with considerably more effort, e.g. for the construction of suitable jigs. An additional advantage of waterjet cutting was the possibility of dealing with offsets and recesses at the same time. Node processing “We also had to come up with some ideas when it came to making the nodes in order to implement the concept from a production point of view with an acceptable amount of effort,” explains Mr Meenen. With the size of the blanks and the amount of material to be machined, determining the machining strategy and its optimisation had a decisive influence on the costs and the implementation times. Hyper Mill CAD- CAM software was acquired specifically to solve this task. The solution that was finally found was based on a threeaxis rough-machining process with quite large tools in a total of only three different chucking operations. By contrast, some of the tooling used for the five-axis finishing operations had to be very small, amongst other things because of the acute angles in the facetted middle section of the nodes. After completion of the machining, the nodes and the mullions were subjected to surface treatment by anodising. The additional tasks included the manufacture of additional mechanical components of the structure especially the so-called connectors used to screw the mullions with a form fit into the nodes as well as ensuring the necessary transport logistics including the delivery of ready-to-install parts on schedule to the construction site. www.aquatec-ndrh.de Author: Klaus Vollrath Oblique cuts, offsets, recesses: when cutting these blanks for the mullions, full advantage could be taken of the benefits of waterjet cutting compared with sawing Vedanta orders HE equipment for its Jharsuguda II project India’s Vedanta Aluminium Ltd has placed a major order with Hertwich Engineering, Austria, for supply and commissioning of three homogenising and sawing units for its Jharsuguda II smelter expansion project. The scope and supply comprises three almost identical continuous homogenising lines, each complete with air cooling, ultrasonic inspection, log saw (long and short type) and packaging equipment as well as all roller tables, log handling equipment and the complete control and automation systems. Hertwich Engineering will be responsible for erection, supervision and commissioning. Total design production is 384,000 tpy of billets with diameters of 152 to 229 mm, commissioning is scheduled in two stages, May and July 2010. Maximum error tolerance of 0.03 percent Weighing technology of the highest precision Calibrated EHP digital crane scales Bühler-based weighing machine specialist EHP Wägetechnik is one of the top addresses worldwide when it comes to extremely demanding weighing operations. The company’s client base covers various sectors such as the metal, paper, automotive, chemical and plastics industries. Boeing or Airbus, BMW or BASF, Porsche or Thyssen – EHP’s reference reads like the Who’s Who of global major players. The company’s product portfolio covers electronic digital crane scales and weighing beams through to data transfer modules that allow wireless transmission of weight values over a distance of several hundred metres from the actual scales to receiving stations equipped with a serial interface. With its main product, crane scales, EHP is the world’s leading supplier to a very special niche market. The scales, which are used to weigh hanging loads, are capable of withstanding the severest of conditions: for example, temperatures in excess of 1000 °C over a burning-hot casting ladle. They continuously transmit precise weight details via a calibrated transmission path. Weighing operations up to 100 tonnes are possible. In order to guarantee this, one needs a considerable amount of expertise, lots of experience, dedicated employees, very high grade production equipment and extremely reliable subsuppliers. The company established a second mainstay over twen- ty years ago with the development and production of load cells / weight sensors. The sensors are used in vehicle, hopper, silo and crane scales. The highest degree of precision is needed in order to assemble the inner workings of load cells under a microscope. The sensors are used later under the most adverse conditions, such as the weighing of loaded trucks. “In principle, they function in a similar way to bathroom scales but in completely different dimensions,” explains Albert Friedmann, the managing director of EHP. This special field is also offered as a service: at the request of a client an EHP employee will travel with a weighing system to a plant, for example to determine the exact weight of an extremely heavy machine that has to be transported. A topic of major importance at EHP is calibration. The company has its own calibration department and testing equipment that is designed for weights up to 50 tonnes and exhibits a maximum error tolerance of 0.03 percent. “The test rig is an in-house development and unique worldwide, something that the calibration authorities are pointing out to us time and again,” says Mr Friedmann proudly. Innovative developments are a characteristic of the company. It presented the world’s first calibrated crane scales in 1986. Today, the product portfolio includes five different model ranges and special requirements can also be met. A task that confronts the company time and again is designing the scales complete with mounting in such a way that they fit perfectly into an existing production facility. EHP also finds solutions for tricky tasks, for example the display of the casting rate. This provides the operator of a crane scales with a digital display of how many kilograms of molten metal a second are being poured into a mould. In foundries, one has to weigh out different materials exactly and then Halle 8.0: 11 Weltmesse für Werkzeug- und Formenbau, Design und Produktentwicklung 2. – 5. Dezember 2009 Messegelände Frankfurt / Main, Germany „Vom Design über den Prototyp bis zur Serie“ Sonderthemen: Automation im Werkzeug- und Formenbau Halle 9.0: Gastland Polen Thermoformen B2B Börse „MoldMatch“ NEU put them together to make special alloys for producing high-quality castings, just like a recipe when baking a cake. The company is represented worldwide with 21 offices in Europe, Asia and North and South America. “Our products are available in Southeast Asia and in Siberia – and, of course, in our home region,” says Mr Friedmann. Jetzt Messebesuch planen! Halle 11.0: Rapid Prototyping für Jedermann Rapid Technologien Werkstoffe Simulation + VR Design + Engineering Design Talents zeitgleich mit EuroMold Internationale Fachmesse für Drehteile, Dreh- und Frästechnik 2. – 5. Dezember 2009 Mit DEMAT international ausstellen! DieMould INDIA amerimold NEU! RosMould asiamold www.ehp.de 18. – 21. März 2010, Mumbai, Indien 11. – 13. Mai 2010, Cincinnati, USA 02. – 04. Juni 2010, Moskau, Russland 15. – 17. Sept. 2010, Guangzhou, China www.euromold.com Veranstalter: DEMAT GmbH / Postfach 110611 / D-60041 Frankfurt / Main / Tel. +49-(0) 69-274003-0 / Fax +49-(0) 69-274003-40 / e-mail: euromold@demat.com / www.demat.com
Page 1 and 2: APT ALUMINIUM NEWS 2 | 06-2008 Volu
Page 3 and 4: APT ALUMINIUM NEWS 4 | 12-2009 Hydr
Page 5 and 6: APT ALUMINIUM NEWS 4 | 12-2009 Redu
Page 7 and 8: APT ALUMINIUM NEWS 4 | 12-2009 EXTR
Page 9: APT ALUMINIUM NEWS 4 2 | 06-2008 12
Page 13 and 14: APT ALUMINIUM NEWS 4 | 12-2009 AUTO
Page 15 and 16: APT ALUMINIUM NEWS 4 | 12-2009 The
Page 17 and 18: APT ALUMINIUM NEWS 4 | 12-2009 1 Sm
Page 19 and 20: APT ALUMINIUM NEWS 4 | 12-2009 4 Fo

2 - ALU-WEB.DE

Create successful ePaper yourself

Delete template?

Save as template?