Cutting Performance in Machining of Large-Sized Spiral Bevel Gears Using Multi-Axis Control and Multi-Tasking Machine Tool

Large-sized spiral bevel gears are usually manufactured based on a cyclo-palloid system and have equi-depth teeth as well as a face hobbing system by a continuous cutting procedure using a special generator. It has been possible to machine the complicated shape because of the development of a multi-axis control and multi-tasking machine tool.The manufacturing method of the gears has been proposed using this development process. In this method, the spiral bevel gears are modeled based on a CAD system and are machined based on a CAM system. In this paper, the cutting performance in machining of the large-sized spiral bevel gears using the multi-axis control and multi-tasking machine toolis investigated. As a result, the relationship between the tool life of end mill and gear accuracy were made clear. The surface roughness and tool mark of the machined gears were compared with those using the special generator.

Semi-Analytical Study of Aerosol Washout by Rain

The accidents of Chernobyl and Fukushima have shown the necessity to better understand all the mechanisms implied in the scavenging of aerosol particles released to the atmosphere during a nuclear accident. Among all the phenomena involved in the deposition of aerosol particles, we focus here on the aerosol particles scavenging by the raindrops below the clouds, also called washout (as opposed to the rainout, which concerns scavenging inside the clouds). The strategy of IRSN to enhance the knowledge and the modelling of any mechanism involved in the washout of aerosol particles by rain spans from environmental studies, to analytical ones. The semi-analytical approach chosen here is halfway between these two modes of reasoning. A companion paper is also submitted to the conference to present the microphysical approach chosen at IRSN. In order to perform this study, aerosol particles were dispersed in the TOSQAN chamber, which is a large cylindrical enclosure (4.8 m height with 1.5 m internal diameter). The aerosol particles once dispersed, synthetic rains of different kinds (from stratiform to convective rains) can be activated. Finally, the instantaneous spectral scavenging coefficients are determined from the spectral decrease of aerosol particles concentration in the chamber as a function of time. In order to be able to produce synthetic rains representative of any tropospheric events, a special generator has been designed; it is based on a vibro-rotative disk. This generator is able to produce monodispersed rains at the top of the TOSQAN chamber with rainfall rates from 7 to 15 mm/h and drops diameters from 0.5 to 2.5 mm injected at velocities close to their terminal one. During these tests, the spectral aerosol concentration is measured in line with the help of a Welas granulometer. This instrument is based on white light scattering. The results of these experiments highlight the influence of “meteorological” conditions inside the chamber on the washout of the chamber atmosphere, especially when the relative humidity is reaching saturation.

Research on EDC Special Pulse Generator and Its Experiments

A modified coating layer had been deposited on the surface of the workpiece with the electrode made of special materials by normal Electrical Discharge Machining (EDM) method in the recent years, and the surface performance had been improved. But, it also has been found that the deposited materials from the electrode can’t be melted fully on the workpiece and the compact coating can’t be formed because of the quencher and quickly heated effect with normal EDM pulse generator in the experiments. And there are other problems existing such as residual stress, crack and so on. In order to solve the above problems, a kind of special Electrical Discharge Coating (EDC) pulse generator is designed in this paper. The hard coating with less crack and higher coating efficiency can be expected with this special generator.