James G. Schroth

Overview of Quick Plastic Forming Technology

General Motors has developed Quick Plastic Forming (QPF) as a hot blow forming process capable of producing aluminum closure panels at high volumes. This technology has been successfully implemented for automotive liftgates and decklids with complex shapes. This talk will review key elements of the QPF process, describe some of the technical achievements realized in this process, and identify areas for future research in process, material, and lubricant development.

Tribological Testing of Graphite and Boron Nitride Lubricant Formulations for High Temperature Aluminum Sheet Forming Processes

The tribological behavior of AA5083 aluminum sheet sliding against tool steel impacts the quality of components manufactured with the elevated temperature metal forming processes such as Quick Plastic Forming (QPF), Superplastic Forming (SPF), or warm forming. This study focuses on the tribological performance and evaluation of alternative solid lubricants using a flat-on-flat tribo-tester to simulate sheet forming at high temperature applications. Improved lubricant formulations containing boron nitride with graphite additions were found to enhance lubricity while maintaining good adherence to the surface of the aluminum blank at a temperature of 450°C.Copyright

High-accuracy iron-loss measurements on motor stator stacks

A new and improved technique is presented for the measurement of iron loss in motor stators. The most accurate existing technique rotates dummy-test rotors, one for each field strength of interest, inside the stators to be tested and measures the reaction torque on the stators. The new technique uses a wound ‘rotor’ component that does not rotate mechanically but does rotate electrically. Therefore, the speed and magnitude of the rotating flux can be controlled electrically without the inherent difficulties of rotating mechanically at high speed and without building different dummy-test rotors for each field strength test.

Non-rotating high-accuracy iron loss measurements on motor stator stacks

Traditionally iron loss in motor stators is measured using loss separation, where overall loss is measured and then other losses like windage, bearings, copper, and rotor losses subtracted. This technique is unsatisfactory because the stator iron loss is typically smaller than the other losses subtracted and therefore a small error percentage wise in one of these other losses leads to a large error in the iron loss. A new technique is described that directly measures the stator iron loss and therefore offers much improved accuracy. This new technique is then applied to a series of known difficult measurements, like effect of temperature on iron loss, compression on iron loss, etc., to demonstrate its veracity and usefulness and to quantify these effects accurately for the first time.

Finite Element Simulation of an Automotive Brake Rotor With Metallic Damping Inserts

A finite element method is developed for simulating the performance of an automotive brake rotor with metallic inserts that are used to dampen the vibration and radiated noise response. The metallic inserts are located in slots that are cast at the edge of the rotor circumference between the two rotor surfaces. Three different rotor configurations are evaluated: (a) an undamped solid rotor, (b) a damped rotor with an unconstrained press-fit metallic insert, and (c) a damped rotor with a constrained cast-in coated metallic insert. Comparisons of the predicted versus measured rotor surface vibration and radiated sound pressure are made to evaluate the effect of the insert and the accuracy of the finite element method. The comparisons show that significant modal damping of the rotor vibration and radiated noise can be achieved through the use of the coated metallic insert. A methodology is developed and applied to evaluate the damping of different metallic inserts and coatings from only the radiated sound pressure response.Copyright