You're Olympic bobsled champions, thanks in part to the proven speed of your handmade blades -- but how do you transfer this to a new standardized material mandated by the sport's governing body? An appeal by Team Kiriasis, the world's top two-person woman's bobsled team, in a German metalworking magazine brought a partnership proposal from world manufacturing leaders Renishaw, Siemens, Sescoi and Iscar. Renishaw used its latest measurement technologies, including REVO™ ultra-high-speed measuring head for coordinate measuring machines (CMMs), to deliver precise data capture of the legacy blade geometry that had carried Team Kiriasis to a world championship in 2005 and Olympic gold at Turin in 2006.
The blade project arose following new rules introduced by the FIBT (International Federation of Bobsleigh and Tobogganing) in October, 2006. The new rules aimed to put an end to ongoing disputes over the use of various materials and treatments in blade manufacture by requiring all bobsled teams to use the same specification steel, with creativity allowed only in blade form.
Driver and team captain Sandra Kiriasis prized the competitive edge achieved by her existing blades, but as these had been created using manual techniques, no drawings or electronic CAD data were available to allow them to be remanufactured using the new standard specification steel. The first step by the Renishaw-Siemens-Sescoi-Iscar partnership was to send the existing blades to Renishaw's UK research facility.
There Renishaw's revolutionary REVO 5-axis measuring head for CMMs was used to scan the blades, quickly capturing many thousands of data points to enable form geometry to be defined in exact mathematical detail.
Unlike conventional touch scanning methods, which rely on speeding up the motion of the CMM's three axes in order to scan quickly, the low-mass REVO head combines horizontal and vertical rotary axes to perform high-speed "infinite" positioning of the touch probe. A 3-D measuring device in its own right, REVO does the direction-changing measuring work to minimize CMM motion errors. REVO's low-mass, low-inertia design allows scanning at speeds of up to 500 mm/sec and capture of 4,000 data points/sec vs 200-300 data points for conventional scanning.
Once the blade geometry data was captured, both DXF and IGES files were created and sent electronically to Sescoi, a software specialist for tool and mold making. A CAD/CAM program was created for a Siemens Sinumerik 840D CNC control and ShopMill HMI fitted to a DMG CNC milling machine located at tooling manufacturer Iscar Germany.
The vast number of data points available to work with enabled high geometric and contouring accuracy as well as very smooth surfaces. The finishing program for the runner surfaces ran 5 MB and contained about 100,000 lines, producing surfaces almost as polished as a mirror.
Following machining, the finished blades were checked for form while still fixtured on the machine tool, using the Renishaw OMP400 touch probe with industry-leading strain gage accuracy. A patented strain gauge sensing mechanism and advanced electronics allow lower, highly consistent contact forces with reduced pre-travel, enabling submicron 3D probe measurement and verification of the contoured surfaces.
Sandra Kiriasis was on hand to personally evaluate the machining. She received runners machined to exactly the same geometry as her championship-winning blades. Mounted to her sled, the new blades performed as well or even better than the old ones, continuing her edge over world-class competition.
Successful blade replication won Team Kiriasis both the 2006-2007 FIBT World Cup and World Championships. In fact, running the new blades, the team won the world championship by more than 2 seconds, the biggest margin ever in championship history where races are usually decided by hundredths of a second.
After taking the gold medal at the FIBT championships in St. Moritz with brakeman Romy Losch, Sandra Kiriasis told TV broadcasters, "The blades are the secret of my success." To show her appreciation, she brought her bobsled in September, 2007 to Renishaw's booth at the EMO machine tool show for display.
Team Kiriasis' success highlights the impact that engineering technologies can have at the highest levels of competitive speed sports, noted Rainer Lotz, managing director of Renishaw GmbH, the company's German subsidiary. "We know about the small margins between success and failure at the highest levels of international sports," he said. "Renishaw is already making significant technical contributions in the world of international motorsport, such as F1 and NASCAR racing, both in engine manufacture and on-car monitoring systems. We have been delighted to add our measurement expertise to the Team Kiriasis blade projects, and look forward to contributing to Sandra's continuing success."