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    Comprehensive analysis of the thermal impact and its depth effect in grinding
    The focus of this work is the analysis of the thermal impact and its depth effect in different grinding processes. The investigated processes cover different kinematics and thus broad ranges of the relative speeds and the intensities of the moving heat source regarding the ground surface. A uniform lower process limit characterizing the onset of grinding burn for the different kinematics is identified by means of the specific grinding power and the contact time. The experimental results together with the theoretical considerations of peak temperatures lead to the conclusion that the process specific range of the contact time is mainly responsible for the thermal depth effect. The results enable the targeted exceeding of the critical process limit in roughing and the subsequent correction by finishing.
    Wissenschaftlicher Artikel
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      135  165
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    Influence of gear hobbing feed marks on the resulting gear quality after discontinuous profile grinding
    Gear hobbing is one of the most common soft-machining processes for pre-toothing. The process kinematics result in a characteristic tooth-flank topography, which is mainly determined by so-called feed marks. For an economical finishing process by gear grinding in automotive applications, the feed-mark depths should not exceed a maximum value of 35 mm. In the present study the validity of this limit has been investigated in view of the development of increasingly powerful grinding machines and grinding wheels. For this purpose, gears with feed-mark depths dx below and above 35 mm were machined and ground by means of discontinuous profile gear grinding afterwards. The influence of the feed marks on the grinding process with roughing parameters was systematically evaluated on the basis of various process variables such as the increase in spindle power Ps or the degree of grinding-wheel clogging Zs, while the resulting gear quality was mainly analyzed by various parameters to describe macro- and micro-geometry deviations of the ground tooth flanks. With increasing feed-mark depth, an increase in spindle power was found due to the additional machined volume. An influence of increasing feed-mark depths on the clogging degree, the grinding-wheel wear and the gear quality could not be proven. Therefore, economical finishing of gears by gear grinding is also possible with feed-mark depths of more than 35 mm. A new definition of this limit should be sought.
    Wissenschaftlicher Artikel
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      119  133
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    Relevance of the region of interaction between the tool and the metalworking fluid for the cooling effect in grinding
    The relevance of the metalworking fluid supply characteristics is well-described for grinding processes. In the presented work, the fluid's interaction with the grinding wheel between the point of impact and the contact zone has been analyzed. For varied supply conditions, deceleration and acceleration effects are obtained and quantified. Furthermore, shadowing effects related to the fluid entrainment towards the contact zone are considered. The observed effects within the region of interaction are consistent with the thermal limits of taper grinding experiments. By revealing the fluid's behavior within the region of interaction, explanation for the effectiveness of supply conditions is given.
    Wissenschaftlicher Artikel
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      118  96
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    Discontinuous profile grinding of multi-phase, case-hardened gears with improved load-carrying capacity
    Highly-loaded transmission components like gears are case hardened for most applications to reach a load adapted strength. The surface layer microstructure as a function of heat treatment decisively determines the achievable load-bearing properties of the component as well as the technological limits of gear grinding. Against this background, this paper deals with the machinability (discontinuous profile grinding) of differently (carburizing and carbonitriding) case-hardened gears with various multi-phase microstructures and improved load-carrying capacity. Therefore, effects of different material phases, precipitates and their distribution in the surface layer on the gear-grinding process will be discussed.
    Wissenschaftlicher Artikel
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      104  113