Distortion Minimization in the Hardening of Large Parts Using Fixture Hardening Machines

HEESS has conducted a detailed examination of the processes during fixture hardening of large gears and bearing rings. The findings have made it possible to selectively counteract the creation of form changes such as out-of-roundness and conicity during the quenching process resulting in significantly reduced distortion. For implementation of these requirements, a hardening machine was designed to process workpieces with an OD of up to 1500 mm. During the early stages of the design process, IWT Bremen provided simulations of the flow around the workpiece which were incorporated in the development. A test series was then carried out to determine to what extent roundness, flatness and conicity can be influenced by fixture hardening, and which influencing factors are decisive in this process. The achievable quality improvements are shown giving the example of rings with an OD of 1100 mm, ID of 800 mm and height of 250 mm.