Randschichthärten typischer Komponenten des allgemeinen Maschinenbaus durch Schleifen

FKM 1999
Booklet No. 245
Project No. 219

Abstract:

The objective of the project (AiF No. 11060) funded by the BMWi via the AiF was the development of adapted grinding processes for process-integrated surface hardening of steel components. To this end, the main mechanisms of action of the short-time metallurgical processes during grinding and the influence of the steepness variables on the grinding hardening process were analyzed. In grinding hardening tests, reproducible crack-free hardening structures were produced, which are characterized by considerable residual compressive stresses in the edge zone. The workpiece speed and the infeed have a significant influence on the hardening depth. Maximum hardening depths of up to 2 mm were achieved at low workpiece speeds and high infeeds with the 42 CrMo 4 v heat-treatable steel. A clear correlation between the cutting speed and the hardening result could not be established. Conventional cutting speeds of Vc = 30 -35 m/s delivered good results. The findings obtained during surface grinding on 42 CrMo 4 v could be transferred to the material C 45 in various initial states and to external cylindrical grinding hardening in further tests. The hardening result during grinding hardening is essentially determined by the composition and the initial state of the material. For example, a finely dispersed carbide distribution in the initial structure favors the hardening result. Hardening and hardening depend in the same way on the carbon content and the content of alloying elements, as is known from conventional heat treatment processes. Microstructural investigations on grind-hardened samples show that the hardening results are comparable to those of laser beam and induction hardening, making grinding hardening a promising process for industrial use. Tests on linear guides from INA Wälzlager Schaeffler KG confirm that real components can be hardened by grinding to meet requirements. The hardening results achieved were comparable with the results of conventional induction hardening in terms of microstructural assessment, hardening depths and residual stresses. Compared with conventional heat treatment processes, grinding hardening offers the advantage of integrating surface layer heat treatment into the process chain in terms of process engineering and material flow. The use of conventional grinding tools, which are not adapted to this innovative process, has proven to be problematic. Without compensating for wear, conventional grinding tools can achieve constant hardening depths on shorter grinding hardening lengths. From this it can be deduced that grinding hardening is currently most suitable for surface layer heat treatments, which can be achieved with short grinding lengths. The objective of the research project was achieved. Scope of report:
59 pages Start of work:
01.01.1997 End of work:
31.12.1998 Sponsor:
BMWi / AiF-Nr. 11060 Stiftung Institut für Werkstofftechnik Bremen, Hauptabteilung Fertigungstechnik Institute Director:
Prof. Dr.-lng. habil. E. Brinksmeier Research group leader:
Dipl.-lng. T. Brockhoff Dr. H. W. Zach, FAG OEM und Handel AG, Schweinfurt Dipl.-lng. R. Ankenbrand, A. Friedrich Flender AG, Bocholt Dr. Bage, INA Wälzlager Schaeffler KG, Herzogenaurach Dipl.-lng. J. Rabe, Sachsen ring AG, Zwickau