Taken from www.designfax.net
Improvements in laser scanning have facilitated the creation of a new protective seat fabrication process for Indy Racing League (IRL) cars. IRL drivers are required to be surrounded by cocoon-like seats designed to protect them during crashes at speeds in excess of 220 mph. The seats are constructed from beaded foam that helps to absorb the gravitational forces that would typically impact the driver, causing injury.
In the past, the driver would sit on top of a bag filled with Expanded Polystyrene beads and resin to leave an exact imprint of their most comfortable driving position. Serving as a human mold, the driver would have to remain motionless for more than an hour until the seat had cured. It is important to have each driver provide the mold for his or her own custom seat design since the quality of the fit improves the seat’s protective abilities during a crash. Every time a car is involved in an accident or a driver switches to a different car, a new seat must be created.
Using laser scanning, Createc Corporation, a supplier of beaded foam, and Bald Spot Sports, a manufacturer of custom racing seats, both located in Indianapolis, IN, have simplified the seat fabrication process. With CAD software, these companies create a 3D virtual reality blueprint of each custom race seat that perfectly fits a driver with each repeated fabrication. Laser scanning the initial foam bead seat model prior to its installation into the racecar creates this blueprint.
Rather than purchasing a laser scanner, the two companies are working with a service bureau called Laser Design, Minneapolis, MN, to provide the required high levels of scanning accuracy and the fast turnaround demanded by the racing industry. Replacement seats are cut using CNC machinery.
“The new process allows us to produce better seats because drivers can obtain duplicates of a seat that fits them perfectly. Before they took the chance that the results of a new seat-fitting process could leave them with a less comfortable seat that would ultimately hurt their performance,” said Cameron Cobb, business development manager for Createc. “Additionally, as seat builders, the new CNC and laser scanning technologies allow us to create seats that provide greater impact resistance because they can be constructed out of new materials that are more compatible with the new molding process.”
The seat-fitting process
Bald Spot Sports produces custom-molded seats for open-wheel IRL racing. Bringing more than 20 years of experience crafting protective race gear to their new products, the team at Bald Spot is continually working to improve the performance and safety of IRL drivers, while reducing the time invested in the process.
The single seat fitting begins by filling a bag with small foam beads, each about 1/8 in. in diameter. Resin is added to the bag to mix with the bead, then the bag is placed into the empty tub of the racecar chassis, and the driver assumes the preferred racing position while sitting on the bag. Bald Spot must ensure that the beads in the bag are able to cover all the critical areas around the legs, back, shoulders and neck, in order to meet published IRL safety standards. A vacuum is applied to the bag while the seat is curing to make sure that the integrity of the preferred seat fit is maintained.
The driver then climbs out of the car after an hour, as the material finishes hardening. Full cure can take up to eight hours. Bald Spot’s seat fabricator trims all the excess material from the bag, a task that typically takes about three hours. The driver returns to double check the seat by climbing back into the car and performing a trial fit. Material is removed from the mold only where the removal gives the driver the freedom needed to steer, shift and work the pedals. This process can take up to another four to five hours. The driver again returns to the seat while the fabricator attaches the head and neck restraint system and the driver evaluates the (hopefully) final fit.
Search for a new approach
The long and painstaking seat fabrication process provides the exact fit required for a safe and comfortable seat. However, the seats produced using this method are designed to protect the driver against only a single impact. Thus, a driver must have a new seat after every accident, which IRL fans know happen all too often. In the past, the entire process of fitting the seat would need to be repeated after every crash. The hassle of the fitting can be compounded after a crash when a driver is injured or experiencing pain, which prevents one from finding or maintaining the most comfortable, preferred race position. Also, it is almost impossible to exactly duplicate that position. Besides the time and expense, a seat with a bad fit can hurt driver performance and risk lessening driver safety.
Engineers at Createc and Bald Spot teamed up to improve this seat design process because they believed they would be able to use a new foam bead formulation to better protect drivers while also eliminating the need for multiple seat fittings. The only piece they were missing was the laser scanning capability to create and store the 3D models required for the CNC machining process.
Scanning technology generates an electronic file that defines complex geometry to such high levels of accuracy that the traditional fitting process is no longer necessary. Laser scanners are able to quickly measure large parts while generating far greater numbers of data points than touch probes, without the need for templates or fixtures. The systems project laser light onto surfaces while cameras continuously triangulate the changing distance and profile of the laser as it sweeps along, enabling the object to be accurately replicated. Since there is no probe on a laser scanner that must physically touch the object, the problems of depressing soft objects and measuring small cavities are eliminated.
How the new process works
The Bald Spot fabricator now uses a portable laser scanner to create a CAD file that perfectly duplicates the seat’s shape. If the driver already has a seat that he likes, then a fitting is not required at all. Instead, the seat itself can be sent to the service bureau for scanning to produce a highly accurate CAD file. The CAD file is used to create a CNC program for a machining center that will carve the seat out of a single block of multiple impact foam.
Using a machine center to carve out the seat makes it possible to use new materials that are rated better for multiple impacts. These new foams provide greater impact resistance and eliminate the need for replacement after minor impacts. Createc has identified a special material — Creasorb, a lightweight, closed-cell foam material — as well suited for racing seats. This resilient material provides excellent shock absorption, withstands multiple impacts, and resists the various chemicals and solvents that are used in the racing industry.
Finding the right service bureau
After making the decision to use laser scanning, Createc and Bald Spot Sports considered purchasing a laser scanning system but decided that it didn’t make sense to purchase a laser scanner at this early stage of the project. “Laser scanning technology is rapidly improving, and we were concerned that our lack of experience with the technology might lead us to a purchase that we would regret later,” Cobb said. “We looked for a service bureau that could guide us through the process while providing the high levels of accuracy and fast turnaround that we need. Unfortunately, our first few attempts in working with service bureaus were not very successful due to their lack of responsiveness. However, the first time we contacted Laser Design, they demonstrated that they had all the capabilities that we needed and were totally dedicated to our success.”
“The project began when one of the drivers in the Indy 500 asked us to provide a duplicate of his current seat,” Cobb continued. “He made the request during race qualification. He could only spare the current seat during a two-day window between his completion of qualifying and the day of the final practice. Needless to say, if we had not returned his original seat to his garage in time due to an unresponsive service bureau, our reputation would have suffered. The day the driver finished qualifying, a member of Bald Spot’s staff took the seat and flew to Laser Design in Minneapolis. Their team scanned the seat the next day, and the Bald Spot crewmember flew back that same night, returning the seat to the driver in plenty of time for the race. Laser Design spent that day converting the scanner-generated point cloud into a surface model. They sent it back to us by the end of the day via email. We produced the additional seat for the driver over the next several days. This extraordinary level of service is actually what we have come to expect on an everyday basis from this highly responsive compa
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