Guba, Nikolai
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Guba, Nikolai
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Guba, Nikolai
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Item-typ:Veröffentlichung, Influence of gear hobbing feed marks on the resulting gear quality after discontinuous profile grindingGear 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 ArtikelBand:31119 126 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Comprehensive analysis of the thermal impact and its depth effect in grindingThe 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 ArtikelBand:70Heft:1134 156 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Relevance of the region of interaction between the tool and the metalworking fluid for the cooling effect in grinding(Elsevier Science, 2022-07-12); ; ; ; 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 ArtikelBand:71Heft:1118 93 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Grinding burn limits: Generation of surface layer modification charts for discontinuous profile grinding with analogy trialsBy means of surface layer modification charts, the occurrence of thermal impact and thus the risk of grinding burn can be detected. With the present work it was shown that surface layer modification charts for discontinuous profile grinding can be generated using analogy trials carried out on a surface grinding machine for investigation of different grinding conditions and varied tilt angles in profile grinding. The experimental and the analysis effort for the analogy trials prove to be significantly more time and cost saving. The results also suggest that system parameters such as the grinding wheel specification or the cooling strategy are taken into account by the specific grinding power. Thus, the experimental results of this work allow the assumption that the determined process limit is not or just to a low extent depending on the system parameters. This assumption is supported by the thermal process limit determined by Malkin and converted in surface layer modification charts. Malkin's limit, identified for different ground steels with surface and cylindrical grinding processes and thus different system and process parameters, corresponds to the results generated in this work at workpieces ground with a kinematically more complex process. The results reveal that there is at least a group of steel materials which seems to share a similar thermal process limit.Wissenschaftlicher ArtikelBand:31731 98 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Influence of the workpiece material on the cutting performance in low frequency vibration assisted drillingFundamental problems in drilling processes are associated with the unfavorable machining conditions in the tool center and the difficult chip removal. Low frequency vibration assisted drilling (LFVAD), in which the linear tool feed is superimposed with a vibratory motion in feed direction, is a promising process to overcome these problems. Aiming at a systematic analysis of the influence of workpiece material properties, results from LFVAD experiments with Ti6Al4V, AlMgSi0.5 and 42CrMo4 in different heat treatment states are presented. Specifically the dependence of optimal oscillation amplitudes on the workpiece material behavior is analyzed.Wissenschaftlicher ArtikelBand:3199 86