Дифракционные решетки с блеском, получаемые на пластинах Si --- первые результаты

Using direct laser lithography and liquid etching of polished vicinal Si(111) wafers, a technology was developed and diffraction gratings 500 /mm with a blaze angle of 4° were fabricated. The manufacturing process of a reflective Si-grating of a triangular profile (sawtooth) can be divided into four main steps: (1) obtaining a pattern of a protective mask for etching grooves; (2) anisotropic etching of grooves in KOH solution; (3) etching to smooth the grating profile and polish the surface of working facets; (4) coating to increase reflectivity. The samples obtained were characterized using scanning electron microscopy and atomic force microscopy methods to determine the shape of the groove profile and roughness: the shape turned out to be close to the ideal triangular, and the root-mean square roughness was less than 0.3 nm. With the help of the PCGrate™ code, taking into account the measured real groove profile, the diffraction efficiency of gratings operating in classical and conical mounts in soft-X-ray and extreme ultraviolet radiation has been simulated. The obtained efficiency values are close to the record ones for the corresponding spectral range and the Au-coating of the grating.

Investigation of Different Groove Profile Effects on Torque Transmission in Shear Mode Magnetorheological Clutch: Numerical Simulation and Experimental Study

In this research paper, an attempt has been made to investigate the torque transmission characteristics in a radial magnetorheological (MR) clutch disc with different groove profiles. To estimate the transmitted torque, a numerical procedure is initiated by the implementation of the Bingham constitutive model into a magnetic field analysis followed by computational fluid dynamic (CFD) analysis. CFD results are presented for the analysis of transmitted torque between a plane driving disc and three different driven discs, i.e., plane, radial groove, and circular groove disc, under the conditions of different working radii, magnetic fields, and rotational speeds. The MR fluid (MRF) domain is modeled using a technique which can be applied for any wall texture of driving and driven disc. To verify the numerical findings, an MR clutch with three different discs and a MR transmission test bed have been built, and the influence of groove profile on the transmission torque of MRFs has been investigated on the test bed. The results are presented to obtain the relationships among torque performance, disc radius, rotational speed, and magnetic field. Numerical results show good agreement of torque transmission for different groove profiles with experiments. Finally, temperature distribution patterns in different three MR clutches and an optimization of the radial groove profile have been analyzed numerically.

Experimental and analytical investigations into wire electrochemical micro turning

Electrochemical turning (ECT) has been studied by researchers for making axially symmetric parts of different materials by using shaped tools fed radially into the rotating workpiece. Despite having various advantages over other advanced machining processes, ECT has failed to gain much attention by the manufacturing industries and researchers because of the complexity involved in designing a shaped tool to give a desired shape and tolerances to the workpiece. In the present work, a systematic study is presented to understand the applicability of a microwire as a replacement for a shaped tool in this process. Simulations are carried out to understand the distribution of electric field lines and current density in case of wire electrochemical turning (ECT). The effects of insulting wire up to different angles on the evolved groove profile are investigated by performing simulation study. Minimum groove width is observed at the lowest value of ‘tool exposed angle’ (30°), while maximum groove depth is observed at the highest value of tool exposed angle (270°). In the later part of the work, an experimental study is performed to characterize a groove profile using a bare copper wire of diameter 200 µm. The effects of input parameters, such as workpiece rpm, tool radial insertion, applied potential and electrolyte concentration on responses like groove width, corner radius and taper angle are investigated. Finally, the understanding of behaviour of different process parameters is applied to perform operations like multi-step turning, microgroove turning and taper turning on copper and micro-threading on stainless steel 304.

KINEMATIC SYNTHESIS OF A COMBINED THREAD STACKER

The article is devoted to the determination of the main characteristics of the combined thread-folding mechanism used for high-speed winding of threads. Based on the previously obtained dependences of the position of the thread for obtaining a cylindrical package, equations describing the groove of the drum groove profile, the reverse sections of the screw drum and the sections between the reverse zones are obtained and solved. Calculations for specific parameters of the mechanism were performed.

Development of the theory of laying a hoisting rope on the drum of a mining hoisting machine

For new designs of mine hoisting machines, the development of scientifically-based solutions to increase the rope capacity and reduce the size of the machines is relevant. Based on the theory of laying the rope on a lined cylindrical drum developed by the authors, it is shown that when choosing a groove profile and winding pitch for a non-lined drum, it is necessary to use a geometric rope laying model, and for taking into account the elastic lining, it is necessary to use a physical model of static interaction of a rope with a scallop of the groove. It is recommended to use the U-tilda-groove profile, which will allow a 4.5 % increase in the drum capacity while maintaining the rope’s curvature radius that is permissible under safety rules during its installation.

Dynamic Exposure Model of Scanning Beam Interference Lithography

To obtain desired photoresist grating by scanning beam interference lithography (SBIL), a precise exposure dose is demanded. For it is difficult to apply the real-time exposure monitoring technology in SBIL, a precise dynamic exposure model is needed to predict the groove profile of the photoresist grating. In this paper, a novel dynamic exposure model is established based on the characteristics of SBIL. Considering the nonlinear properties of the photoresist, a three-dimensional development process simulation is conducted based on cellular automata (CA) model. Based on this model, the influence mechanism of exposure parameters on groove profile can be analyzed, which provides an effective analysis method for optimizing exposure parameters of SBIL.