Advancements in Induction Gear Heat TreatmentMr. Neil Merrell, Contour Hardening Inc.
Mr. Merrell is a recent Purdue University graduate, and has been a co-operative student with Contour Hardening Incorporated.
Mr. Merrell presented the advantages of Contour Hardening's "Single Station", "Dual frequency", and "Micropulse" approaches to case hardening gear teeth. By use of a Mid-Frequency heat up, the bulk of the gear tooth is preheated, ensuring that subsequently the "Micropulse" will uniformly case harden each tooth, without "through hardening" which results in a "brittle" tooth and has been a major problem with past induction hardening techniques. The "Micropulse" electronics allow very fast rise times on power which coupled with precision spin and quench control ensures maximum uniformity of case around the gear.
In a typical sequence, a gear is preheated at mid frequency while spinning, translates axially to a high frequency coil for case hardening and is quenched in-place by the coils built-in quenching system. A full cycle takes less than 30 seconds. With selection of appropriate "higher carbon" steels, the case created matches those of traditional carburizing for uniformity, depth, and hardness. Single station operation allow the process to easily integrate into flexible workcells, and just-in-time manufacturing concepts, since it is not a batch process.
Mr. Merrell concluded by showing other developments at Contour Hardening Inc. including a new machine with orbiting coils, allowing customized surface hardening of each section of a drive shaft.