Untersuchungen zum Einsatzverhalten schleifgehärteter Komponenten des allgemeinen Maschinenbaus

FKM 2002
Booklet No. 266
Project No. 239

Abstract:
In a previous research project on grinding hardening (AiF No. 11060), the procedural principles of this novel approach were developed and the properties of grinding-hardened surface layers were characterized. However, some fields of action were identified which had to be investigated in further research work. The aim of this project, which was funded by the German Federal Ministry of Economics and Technology (BMWi) via the German Federation of Industrial Research Associations (AiF), was to further develop grinding hardening in order to create the necessary conditions for industrial use. The work focused on the development of approaches to increase process reliability, strength tests on grinding-hardened parts and the determination of the manufacturing costs incurred during grinding hardening. In order to increase process reliability during grinding hardening, various solutions were developed with the development of adapted grinding wheel specifications, the use of continuous dressing and the use of cooling lubricant. In the process, tool specifications were derived which are adapted to the stresses present during grinding hardening. Resin-bonded corundum grinding wheels with tough corundum types and coarse grains proved to be the most suitable. Investigations into grinding hardening with continuous dressing and the use of cooling lubricant showed that these measures stabilize the grinding hardening process. Through these process control strategies and the adaptation of the tool specification, the prerequisites for the reliable use of grinding hardening under industrial conditions were developed in the research work carried out. With regard to the process control for grinding hardening, it can be stated that grinding hardening can be used in dry grinding with short grinding paths for reliable surface hardening. When grinding hardening using cooling lubricant, larger infeeds and lower feed rates must be set to achieve comparable hardening depths. Due to the temperature control of the machine tool, the reduction of tool wear and the more uniform workpiece temperature, a stable process and a continuous hardening result can be achieved, even over longer grinding paths. Grinding hardening using cooling lubricant is therefore recommended for components with longer grinding paths and low material volumes. The cost comparison between grinding hardening and induction hardening showed a significantly lower hourly machine rate for grinding hardening, but higher direct production costs due to the higher productivity of the induction hardening system. The cost calculation also shows that grinding hardening is a cost-effective alternative to induction surface hardening if the process conditions are adapted. The strength tests have shown that the sliding wear resistance of grind-hardened samples corresponds to the wear resistance of induction-hardened samples. Furthermore, a significant increase in fatigue strength can be achieved by grinding hardening compared to pre-hardened samples. Grinding hardness tests on joint hubs made of Cf 53 N proved that grinding hardening using cooling lubricant can be used for surface hardening of components of practical relevance. The objectives of the research project were achieved. Scope of report:
94 pages Start of work:
01.11.1999 End of work:
31.10.2001 BMWIlAiF-No.:
12197 Stiftung Institut für Werkstofftechnik (IWT) Hauptabteilung Fertigungstechnik Head:
Prof. Dr.-lng. habil. E. Brinksmeier Dipl.-lng. T. Wilke Dipl.-lng. Beyer (Renk AG) Dr.-lng. M. Klaiber (SEW-Eurodrive) Dipl.-lng. P. Roll (DaimlerChrysler) Dipl.-lng. J. Rabe (Sachsenring AG) Dipl.-lng. P. Köpf (ZF)