■The Giant Interior Hypotrochoid Ramp
The symbolic ramp of Bloomberg’s European Headquarters forms a smooth continuous three-dimensional loop between floors. The 210meters long ramp was realized using two of Kikukawa’s welding technology, FSW(friction stir welding) and fibre laser welding.
The largest of these dual-curved panels is 2600mm by 2731mm, and 450kg in weight. In order to implement these curved bronze panels, new technology was adopted and tested through sample and mock-up fabrications. Difficulties or challenges found through these experimentations were reflected in the drawings and used to fix the basic details.
■Creating an Invisible Joint, FSW (Friction Stir Welding)
These panels required metal sheets that exceed the size of market available metal sheets. Thus, Kikukawa fabricated these sheet metals by welding with FSW.
While the typical market available bronze sheets are 1250mm in width, the maximum panels are over 2500mm. Thus, up to 3 metal sheets were welded for implementation. As the metal curving process requires material strength and any discolouration from the welding would result in an uneven sulfurization, this process required great care and quality control.
■Creating an Invisible Joint, Fibre Laser Welding
The ramp draws a complex dual-curvature shape as it goes up the floors. These panels are implemented using multi-mode fibre-laser welding. Kikukawa developed its own jigs to fully utilize the advantages of these machines; high-quality and long-distance curved welding.
■Curving Bronze Panels
In order to maintain the curvature and flatness of the outsized bronze curved panels, Kikukawa developed a new methodology, honeycomb-backed curved bronze panels.
In developing this new methodology, there were various difficulties: including the few known examples of honeycomb adhesion to bronze panels, the curvature, and the large size of the panels. Kikukawa designed the jigs and made various improvements including mitigation of the influence of the adhesion process to the panels, or the revision of the sulfurization process. Through these experimentations and improvements, Kikukawa was able to meet the requirements of the project.
■Considering One Panel at a Time
In order to optimize the installation process including lifting, uniquely shaped frames were used. As the shapes of these panels differ within floors, the patterns of fixing brackets varied. Some panels had limited lifting points thus the fixing bracket placements were limited, a difficulty overcome by considering the installation process from the design stage.
The hypotrochoid interior bronze ramps truly reflect Kikukawa’s metal craftsmanship: from the consideration of these frames and the use or development of new methodologies.
|Hypotrochoid ramp||Bronze||HL+FURUMI (sulfurized) finish
Fiber laser welding
Dual Curving Technology
Honeycombed Curved Panel
|Project||Bloomberg London, Hypotrochoid Ramp|
|Abbreviated Name||Bloomberg’s European headquarters|
|Architect||Foster + Partners|
|Contractor||Main Contractor：Sir Robert McAlpine Ltd. |
Facade Contractor：Josef Gartner