Enhancing Control Of Distortion Through "One Piece Flow - Heat Treatment" Authors: V. Heuer, D. Bolton, K. Löser, T. Leist


Proper control of distortion has become even more important on new powertrain designs. To answer the demand for fuel­efficient vehicles, modern transmissions are built much lighter, therefore the components of the transmission exhibit less wall thickness which makes them more sensitive to distortion. Distorted gear components can create noise in the transmission, require post heat treat machining processes and may even create problems during transmission assembly.
By applying the technology of Low Pressure Carburizing (LPC) and High Pressure Gas Quenching (HPGQ), the distortion caused by heat treatment can be significantly reduced. This technology has been successfully established in serial production for many different gear applications.
With the introduction of 'One Piece Flow ­ heat treatment', the distortion control can be further enhanced. This 'One piece Flow - heat treatment' allows for a rapid case hardening where the components are low pressure carburized at high temperatures (1050°C) followed by gas quenching. The components are not treated in conventional big batches with multiple layers, but they are treated in small batches consisting of one layer only. The quench intensity is controlled more precisely to allow for processes which are customized individually for each gear­component. The single­layer treatment provides
S homogenous and rapid heating of the components,
S homogenous and rapid carburizing of the components,
S homogenous and precisely controlled gas quenching.
All the variations from layer to layer are eliminated, which leads to reductions in distortion­variation within the load.
In addition, this new technology allows strong costs­savings for logistics. The manufacturing­line can be completely automated since the parts are 1st taken one by one from the soft machining unit, then 2nd heat treated in time with the cycle­time of soft machining ("Synchronized heat treatment") and then 3rd passed down one by one to the hard machining unit. The paper presents applications for enhanced distortion control when using 'One Piece Flow ­ heat treatment'.
ISBN: 1-978-61481-054-4 Pages: 14
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