As automakers turn their attention to fuel-efficient vehicles, new manufacturing challenges arise. For example, capitalizing on nascent technologies such as regenerative braking is a big step forward, provided one can reduce the higher production cost of hybrid vehicles.
Simplifying automation processes and reducing overall machine equipment costs are critical steps in reducing these costs. Such was the challenge General Motors faced when the company began engineering hybrid versions of its Escalade and Tahoe models. GM designed into its vehicles a regenerative braking system, which captures kinetic energy normally lost to heat when braking, and converts it to electric power. The system includes a generator with copper windings that must be coated with contamination-resistant powder.
Providing a system to coat the windings is HeatTek of Ixonia, Wis., a challenging application that required HeatTek to fit equipment into a limited space. Adding to the difficulty, a large moment load is required to maintain repeatability due to a single-stanchion mounting location for the mechanics. Given these challenges, HeatTek turned to motion control integrator Sure Controls, Greenville, Wis. Together, the two companies worked with Parker Hannifin’s Electromechanical Automation Division to design a motion solution capable of hitting the repeatability spec while maintaining the small work envelope. The motion system consists of Parker’s Xpress HMI, ACR controls, Aries drives, MPP motors, PS gearboxes, and HPLA and ET series mechanics.
“Essentially we needed to fit a gantry-style system into the workspace of a compact robot,” says Tom Widmer of Sure Controls. Multiple customizations were made to the stanchion mounting, motor orientation, and cable track routing of the HPLA series mechanics to minimize the overall footprint. On the electronics side, the controller and servo drives were chosen for their Ethernet Powerlink (EPL) motionbus technology, which allows the machine to take advantage of Parker’s Drive Talk feature. With Drive Talk, the controller automatically accesses drive parameters for advanced control, display, and diagnostics in a seamless mapping between the two devices.
Peter Caine, HeatTek vice president, explains that accuracy is paramount for the powder epoxy pre-heat-and-cure system. “We load an uncoated part onto what is essentially a rotary table consisting of 11 radial spokes. After 11 index moves, the system has turned one revolution and the part has gone through 11 stations,” he says. The system indexes to the next station every three minutes. The uncoated part first goes through three preheat stations. “At the fourth station, there’s a pick-and-place unit where we loosen the part on the fixture. The X-Z pick-and-place grabber then moves over the part, grabs it, and moves it radially outward. The part is then turned 90°, and travels down the Z axis for the powder epoxy coating application.”
After the powder application, the process is reversed and the coated part is put back on the fixture where it’s indexed into five post-heat stations and then back to the 11th and final unload station. “The critical part for us was grabbing the part in the correct position while rotating and supporting it without letting it fall. It’s a 30-lb part and the accuracy of the vertical Z-axis travel is critical to meeting up with the powder epoxy application,” says Caine. He also notes that the machine won’t be processing the same part every time, but is smart enough to accommodate different parts with an easy parameter change on the HMI.
For more information, visit Parker Hannifin Corp.