Contact fatigue and bending fatigue are two main failure modesof steel gears. Surface pitting and spalling are two common contactfatigue failures, which are due to the alternating subsurface shearstresses from the contact load between two gear mates. When a gearis in service under cyclic load, concentrated bending stressesexist at the root fillet, which is the main driver of bendingfatigue failures. Heat treatment is required to increase thehardness and strength of gears to meet the required contact andbending fatigue performance. Induction hardening is becoming morepopular due to its process consistency, reduced energy consumption,clean environment, and improved product quality. It is well knownthat an induction hardening process of steel gears can generatecompressive residual stresses in the hardened case. Compressiveresidual stresses in the hardened case of tooth flank benefit thecontact fatigue performance, and residual compression in the rootfillet benefits the bending fatigue. Due to the complex geargeometry, the residual stress distribution in the hardened case isnot uniform, and different induction hardening process can lead todifferent residual stress pattern and significant variation offatigue performance. In this paper, an innovative approach isproposed to flexibly control the magnitude of residual stress inthe regions of root fillet and tooth flank by using the concept ofpreheating prior to induction hardening. Using an external spurgear made of AISI 4340 as an example, this concept of innovativeprocess is demonstrated with finite element modeling, usingcommercial software DANTE.
- Edition:
- 13
- Published:
- 09/01/2013
- Number of Pages:
- 13
- File Size:
- 1 file , 890 KB
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