Powder Metallurgy is a proven technology to produce high strength gears for the automotive industry. Advances in powder production, compaction, and sintering combined with double pressing have enabled overall part densities up to 7.5 g/cm3 in spur gears. However, helical gears are more difficult to produce to these same densities because the geometry does not lend itself to the DP/DS process. Described in this paper is a P/M parts making technology capable of producing single pressed and sintered helical gears with core densities approaching 7.4 g/cm3. Description of a prototype run will be presented with the resulting sintered part densities and part-to-part variability. Beyond the development of the new binder/ lubricant system, surface densification is a manufacturing technology capable of producing full density on the surface of the gear with full densification ranging from a minimum of 0.38-mm to a maximum of 0.70-mm. This surface densification creates a composite component giving the benefits of pore free density in the critically stressed case region of the part with aprox. 95% density in the core to provide for the required core properties. In addition to the densified case structure, the surface finish of the rolled part is better than that of a ground finish. Surface densification has the added benefit of producing a part with high dimensional precision. Lead and involute gear checking of the as rolled gear shows that the gear error is equivalent to a conventional machined wrought steel gear. Additionally, the roll densification process was able to produce a crown on the gear that further enhances the NVH performance of the gear. Gear crowning is impossible to achieve through P/M part compaction, the consistency of the crowning is a direct consequence of the uniformity of sintered density through out the part and expert engineering of the rolling process to produce this feature. Additional experimental work is required to produce the helical gear with the depth of densification achieved in the test samples.
Powder metallurgy of high density helical gears
2003
17 Seiten, 12 Bilder, 6 Tabellen, 13 Quellen
Conference paper
English
Powder Metallurgy of High Density Helical Gears
SAE Technical Papers | 2003
|Powder metallurgy of high density helical gears
Automotive engineering | 2003
|Powder Metallurgy of High Density Helical Gears
British Library Conference Proceedings | 2003
|Engineering Index Backfile | 1946
|Engineering Index Backfile | 1946
|