(V) Case study- Laser Weld Technique of Integral Gear for Tandem Axle

Monday, September 13, 2021: 10:40 AM
223 (America's Center)
Mr. Yathish Rao , Industry Professional, PUNE, India
Integral Gear is the one primary member in Tandem Axle particularly in leading axle, because it has to transmit the power from Transmission to Trailing axle. In Particular -integral gear receives torque from inter axle differential and transfers to lower helical gear. This particular gear is combination of Helical, bevel and Curvic Tooth profile. This gear has bevel gear teeth on one side , curvic coupling on the other side and helical gear on circumference. Generally this gear is produced from Precision Forging route and tooth by machining. But in this study, this gear is split in to 2 portions in order to ease the manufacturing process and later laser welded. The Side Gear portion of integral gear separated from Helical & Curvic Tooth. The Laser weld Joint is designed by concept development ,FEA simulation for particular Torque to meet the Fatigue life of the part. Laser weld specification is defined considering the U groove with Gas Pocket. Also Penetration depth, Face width, HAZ & Fusion zone Hardness, Acceptable cracks, Porosity, Inclusions all are defined with respect to the joint design. CO2 Laser machine with 6KW power is used to Produce the Part with the filler material electrode AWS 5.14M Class ErNiCr3 as the Gear Material used is 20MnCr5. Pre-requisite is considered removal of carburizing case and press fit before Laser weld to achieve intact joint. The 6 samples are Bench validated. All the samples suspended at 3000 cycles for Torsional Abuse & 300000 cycles for Torsional Fatigue as performance of parts exceeded the life. The parts are evaluated for Metallurgical Joint analysis. The Laser weld geometry, Penetration, HAZ hardness, Fusion Zone hardness, Cracks , Porosity, inclusion all are evaluated. No evidence of influence of Laser weld defects on Part performance observed However improvement in Laser weld process is considered.