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排序方式: 共有166条查询结果,搜索用时 500 毫秒
1.
Metal bonded grinding tools offer a remarkable potential for micro grinding because of their favorable wear behavior. However,
metal bonded grinding tools, especially dicing blades, are hard to dress by conventional dressing methods. Electro contact
discharge dressing, which is presented in this paper, is a numerically controlled dressing process offering the possibility
to create the geometry and topography of the grinding wheel simultaneously at negligible dressing forces. The power of an
electric circuit thermally removes the metal bond of the grinding wheel during the dressing process. The quality of the created
profiles and the influence of the dressing parameters on the specific material removal rate of the grinding tool as well as
the wear of the electrode are investigated at fine-grained grinding wheels. 相似文献
2.
We prove that the function of normalization in base , which maps any -representation of a real number onto its -development, obtained by a greedy algorithm, is a function computable by a finite automaton over any alphabet if and only if is a Pisot number.Christiane Frougny was supported in part by the PRC Mathématiques et Informatique of the Ministère de la Recherche et de l'Espace. 相似文献
3.
4.
V. Böß B. Denkena V. Wesling S. Kaierle F. Rust D. Nespor B. Rottwinkel 《Production Engineering》2016,10(4-5):433-441
Due to rising costs of raw material, companies of the aerospace industry increasingly seek to repair components of aircraft engines instead of replacing them. Particularly the clad repair of turbine blades made of high strength nickel-base alloys with directionally solidified or single crystalline structure is a difficult issue, especially due to high requirements regarding the conditions of the final part surface. The present work deals with the question whether the prediction of surface and subsurface conditions, e.g. surface topography and residual stresses, is possible after repairing the inhomogeneous nickel-base alloy Rene 80. For this purpose, laser deposition cladding is applied for the polycrystalline Rene 80, using the filler material Rene 142. In the following re-contouring process, the claddings are milled with a ball end mill cutter. The influence of the inhomogeneous base material and the shape of the clad on the cutting forces as well as the final part surface are experimentally investigated. Superficial residual stresses are measured and evaluated. The cutting forces and the final surface reveal characteristic variations in the area of the material deposition and the dendrites. A geometric process simulation shows that the prediction of cutting forces and surface conditions for the polycrystalline material is only possible to some extent. 相似文献
5.
Berend Denkena Jan Brüning Lars Windels Dirk Euhus Stefan Kirsch Daniel Overbeck Thomas Lepper 《Production Engineering》2017,11(6):715-722
Today, machining of large, integral constructed structural parts requires expensive machining centers. In contrast, modern industrial robots are suitable for a wide field of applications and are characterized large working spaces and low capital investment. Therefore, they provide high economical potential for machining applications in aerospace industry, especially for the machining of near to shape pre-products like extruded profiles. However, their constructive characteristics like low stiffness and high sensitivity to vibrations lead to disadvantages compared with conventional machining centers and have to be considered during process planning. Therefore, several methods for offline and online optimization of robot machining processes were developed and integrated in a new process chain for manufacturing of structural fuselage parts. Thereby, the conventional CAD–CAM process planning chain was extended with simulation based analysis and optimization methods and a load-depending trajectory planning. These methods for offline process optimization within this novel process chain are presented in this paper. 相似文献
6.
Chip formation in grinding: an experimental study 总被引:1,自引:1,他引:0
Due to high cutting speeds and low single grain chip thicknesses no reliable approach to interrupt the cut in grinding was
realized so far. This paper presents a new method to experimentally obtain and analyze chip roots during up-grinding. By means
of high resolution SEM-micrographs several chip roots are analyzed, classified and discussed with regard to the fundamental
chip formation and material removal mechanisms. Furthermore, there are conclusions drawn about the distribution and number
of the active grains, which are in a good correlation with the Abbott-curve of the grinding wheel layer and the process parameters. 相似文献
7.
The productivity in High Speed Cutting is often limited by undesirable vibration effects in the main spindle (chatter). In
many cases these limits are far below the technically possible cutting parameters provided by the machine technology. This
paper presents a new approach to a motor-integrated milling spindle with an embedded electromagnetic actuator to actively
reduce chatter vibrations and increase productivity. It is based on the non-contact application of highly-dynamic damping
forces on the spindle shaft. That way the process stability can be increased significantly. By measurement and simulation-based
analysis of spindle dynamics and transient and analytical approaches to process stability, the efficiency of the damping method
is demonstrated in theory. Finally, a new, soft magnetic composite based motor-integrated electromagnetic actuator is introduced
in this article. 相似文献
8.
The resulting surface quality after 5-axis ball end milling is of superior importance because finish milling is often the last process step determining the functional performance of a component. However, the prediction of surface topography is still a challenging task. Especially in ball end milling with the characteristic sickle shaped chip cross section, ploughing effects in the area of low chip thickness result in plastic deformation and surface defects (also known as burr). This paper provides a new approach to predict those surface defects by considering the minimum chip thickness for complex milling engagement conditions within a virtual process design. This allows the choice of suitable process parameters without extensive experimental efforts. 相似文献
9.
The residual stress state of coatings influences tool life and performance in machining significantly. Due to thermo-mechanical loads during the cutting process the coatings require tailored properties. Beside the coating structure the two most important properties are the residual stress state and the chemical composition of the coating. Therefore, the influence of these two properties is investigated in this study, comparing the cutting performance in continuous and interrupted cutting of 42CrMo4 (AISI 4140) and Ti–6Al–4V. It is shown that the residual stress states of the coating close to the surface and close to the substrate are important for the wear behavior. High compressive residual stresses near the substrate combined with a material-optimized composition increase the resistance against chipping. Flank wear resistance increases with high compressive residual stresses near the surface and decreasing stresses towards the substrate. 相似文献
10.
Kathrin Landgraf Andreas Kühnapfel Maria Schlanstein Ronald Biemann Berend Isermann Elena Kempf Holger Kirsten Markus Scholz Antje Krner 《International journal of molecular sciences》2022,23(8)
Obesity develops early in childhood and is accompanied by early signs of adipose tissue (AT) dysfunction and metabolic disease in children. In order to analyse the molecular processes during obesity-related AT accumulation in children, we investigated genome-wide expression profiles in AT samples, isolated adipocytes, and stromal vascular fraction (SVF) cells and assessed their relation to obesity as well as biological and functional AT parameters. We detected alterations in gene expression associated with obesity and related parameters, i.e., BMI SDS, adipocyte size, macrophage infiltration, adiponectin, and/or leptin. While differential gene expression in AT and adipocytes shared an enrichment in metabolic pathways and pathways related to extracellular structural organisation, SVF cells showed an overrepresentation in inflammatory pathways. In adipocytes, we found the strongest positive association for epidermal growth factor-like protein 6 (EGFL6) with adipocyte hypertrophy. EGFL6 was also upregulated during in vitro adipocyte differentiation. In children, EGFL6 expression was positively correlated to parameters of AT dysfunction and metabolic disease such as macrophage infiltration into AT, hs-CRP, leptin levels, and HOMA-IR. In conclusion, we provide evidence for early alterations in AT gene expression related to AT dysfunction in children and identified EGFL6 as potentially being involved in processes underlying the pathogenesis of metabolic disease. 相似文献