scholarly journals ТЕХНОЛОГИЧЕСКИЕ ВОЗМОЖНОСТИ ПНЕВМОУДАРНОЙ ШТАМПОВКИ ВЫТЯЖКОЙ ТОНКОЛИСТОВЫХ ДЕТАЛЕЙ

2018 ◽  
pp. 45-51
Author(s):  
Е. А. Фролов ◽  
С. Г. Ясько ◽  
С. И. Кравченко
Keyword(s):  
Thin Film ◽  
High Speed ◽  
Spherical Shape ◽  
Deformation Parameters ◽  
Pneumatic Impact ◽  
Spherical Elements ◽  
Thin Walled ◽  
The Stability

The determination of the deformation parameters for high-speed extraction of axisymmetric thin-film blanks that ensure the shaping of parts without distortion of the shape of the relief and destruction of metal by the method of pneumatic impact punching is performed. On the basis of the conducted researches the technological possibilities of manufacturing of quality axisymmetric thin-walled details by the method of pneumatic impact punching are established. The conditions for the stability of the workpiece when forming the axisymmetric elements of a non-spherical shape are similar to the conditions for the stability of the workpiece during the shaping of spherical elements, and the results can be extended to the drawing of elliptical, shallow conical and other similar parts. Pneumatic impact punching allows you to pull dome-shaped parts without the use of hanging thresholds, two-transversal stamping and other special techniques with a relative billet thickness of two to four times less than allowed when drawing a punch.

Study on the Stability of High-Speed Milling of Thin-Walled Workpiece

2010 ◽  
Vol 97-101 ◽  
pp. 1849-1852
Author(s):  
Tong Yue Wang ◽  
Ning He ◽  
Liang Li
Keyword(s):  
Aluminum Alloy ◽  
Machine Tool ◽  
High Speed ◽  
Modal Parameters ◽  
Inertia Effect ◽  
Cutting Force Coefficients ◽  
High Speed Milling ◽  
Machining System ◽  
Thin Walled ◽  
The Stability

Thin-walled structure is easy to vibrate in machining. The dynamic milling model of thin-walled workpiece is analyzed based on the analysis of degrees in two perpendicular directions of machine tool-workpiece system. In high speed milling of 2A12 aluminum alloy, the compensation method based on the modification of inertia effect is proposed and accurate cutting force coefficients are obtained. The machining system is divided into “spindle-cutter” and “workpiece-fixture” two sub-systems and the modal parameters of two sub-systems are acquired via modal analysis experiments. Finally, the stability lobes for high speed milling of 2A12 thin-walled workpiece are obtained by the use of these parameters. The results are verified against cutting tests.

Spherical shape stability of shells and cavities

2007 ◽  
Vol 5 ◽  
pp. 38-59 ◽  
Author(s):  
M.A. Ilgamov
Keyword(s):  
Spherical Shape ◽  
Past Century ◽  
Shape Stability ◽  
Thin Walled Structures ◽  
The World ◽  
Thin Walled ◽  
The Stability ◽  
Working Media ◽  
Reliable Methods ◽  
Spherical Shape Stability

Thin-walled shells characteristic of their light weight and strength are used everywhere – in household items to ocean liners and space rockets. Their applications are so diversified and uncountable that one can safely say, ”The world consists of shells; the world rests on shells.” After all, the Earth’s crust is also a shell. The wide application of thin-walled structures has triggered the need for developing reliable methods to calculate their strength and stability, and this is just the research subject of the shell theory, a new branch of mechanics arisen in the past century. The important role is found to be played by their interaction with working media. The present paper discusses the issues on the stability of spherical thin-walled shells and gas cavities in liquid.

The stability of vapor film immersed in superfluid helium on the surface of the hot ball

2016 ◽  
Vol 230 (6) ◽  
pp. 433-439 ◽  
Author(s):  
Ali Jahangiri ◽  
Mojtaba Biglari
Keyword(s):  
Thin Film ◽  
Heat Flux ◽  
Numerical Method ◽  
Critical Heat Flux ◽  
Superfluid Helium ◽  
Spherical Shape ◽  
Vapor Film ◽  
The Stability

In this article, the evolution of vapor film on the surfaces of hot objects immersed in a cryogenic superfluid helium liquid is considered. It is assumed that at the beginning of the process, a thin film of steam exists on the surface of the object that has a spherical shape. If the heat flux is greater than the critical heat flux, the growth of vapor film will continue, otherwise it will collapse. Survey and analysis of the previously mentioned problem has been done using numerical method and the main onjectives are as follows: (a) study the evolution of the vapor film immersed in superfluid helium on the surface of the hot ball and (b) the stability of vapor film immersed in superfluid helium on the surface of the hot ball.

Improved Generalized Procedure for Determining Critical State of a Thin-Walled Beam Under Combined Symmetric Loads

2019 ◽  
Vol 19 (08) ◽  
pp. 1950098 ◽  
Author(s):  
Phung Van Binh ◽  
Nguyen Viet Duc ◽  
Prokopov Vladimir Sergeevich ◽  
Dang Hoang Minh
Keyword(s):  
Bending Moment ◽  
Complex Loading ◽  
Computational Procedure ◽  
Beam Length ◽  
Concentrated Load ◽  
Internal Forces ◽  
Thin Walled ◽  
The Stability ◽  
External Loads

This paper presents an improved generalized procedure for dealing with the stability of thin-walled beams under combined symmetric loads based on the energy method. The differential equations for the case of complex loading conditions were developed using an axis transformation matrix. The work caused by external loads was related to the work of internal forces to simplify the computational procedure. The thin-walled beam subjected to axial force [Formula: see text], bending moment [Formula: see text] at both ends, and concentrated load [Formula: see text] at midspan was studied. The case of a concentrated load [Formula: see text] replaced by a distributed load [Formula: see text] over partial beam length was also examined. The stability region boundary of the beam was derived by two approaches: one was to estimate an approximate angle of twist prior to determination of the deflection and the other was to do it in the reverse way. Numerical results reveal that the first approach yields less error than the second; however, the outcome obtained by the former was more cumbersome than the latter. Above all, both approaches provided feasible results and are useful for further applications dealing with the stability analysis of thin-walled beams.

Experiments on the stability of viscous flow between rotating cylinders - VI. Finite-amplitude experiments

1965 ◽  
Vol 283 (1395) ◽  
pp. 531-556 ◽  
Keyword(s):  
Stability Problem ◽  
High Speed ◽  
Amplification Factor ◽  
Finite Amplitude ◽  
Taylor Number ◽  
The Difference ◽  
The Stability ◽  
Speed Computer ◽  
Linear Stability Problem

The ion technique is applied to a variety of experiments in Couette flow: determination of the critical Taylor number; determination of wavenumber and waveform of the vortices; establishment of the laws that the square of the amplitude and the amplification factor both vary as the difference between the Taylor number and the critical Taylor number; and finally certain studies of the growth and decay of vortices as the Taylor number is changed. The experimental data are compared with the results of integration of the exact equations for the linear stability problem by means of a high-speed computer. These theo­retical values were obtained by P. H. Roberts and are presented in an appendix to this paper.

Stability Limits of High-Speed Milling of Thin-Walled Workpiece

2012 ◽  
Vol 426 ◽  
pp. 303-308 ◽  
Author(s):  
Tong Yue Wang ◽  
Ning He ◽  
Liang Li
Keyword(s):  
High Speed ◽  
Modal Parameters ◽  
Inertia Effect ◽  
Cutting Force Coefficients ◽  
High Speed Milling ◽  
Stability Lobes ◽  
Machining System ◽  
Thin Walled ◽  
The Stability ◽  
Stability Limits

In order to control chatter in machining of thin-walled workpieces, the dynamic model of milling od thin-walled workpiece is analyzed based on considering the flexibility of the workpiece and the machine. In high speed milling of 2A12 aluminum alloy, the compensation method based on the modification of inertia effect is proposed and accurate cutting force coefficients are obtained. The machining system is divided into “spindle-cutter” and “workpiece-fixture” two subsystems and the modal parameters of two subsystems are acquired via modal analysis experiments. A method for obtaining the stability lobes is presented by considering the relative movement of both subsystems. Finally, the stability lobes for high speed milling of 2A12 thin-walled workpiece are obtained and compared between considering three kind of modal parameters. The results are verified against cutting tests.

The Analysis of Influence of Sheet Properties on the Ironing Process of Thin-Walled Cylindrical Shell Products from Aluminum Alloys

2015 ◽  
Vol 641 ◽  
pp. 232-245 ◽  
Author(s):  
Artur Rękas ◽  
Tomasz Latos ◽  
Robert Budzyn ◽  
Marcin Fijałkowski ◽  
Łukasz Brodawka
Keyword(s):  
Cylindrical Shell ◽  
Aluminum Alloys ◽  
High Speed ◽  
International Standards ◽  
Raw Material ◽  
Forming Process ◽  
Multi Stage ◽  
Thin Walled ◽  
The Stability ◽  
The Impact

In industrial practice, where the amount of products produced in a minute is calculated in hundreds of units, the ironing process of thin-walled cylindrical shell products is carried out with very high speed. In the multi-stage forming process it is important to ensure the stability of parameters of the raw material. Properties of input sheets are defined in international standards, but after the rolling process the properties of input tapes may be various while still in the acceptable tolerance. Differentiation of properties of sheets has a significant impact on the progress of the examined process. The multi-stage forming process requires raw material with a high susceptibility to deformation and an adequate level of plasticity margin. In this study tapes of equal thickness and similar chemical composition from various suppliers have been analyzed. Selected aluminum alloys sheet are currently used in Europe in production of beverage packaging. On the basis of uniaxial tension test results, plasticity margin for a selected tape has been determined. Deformation range and plasticity margin have been analyzed in relation to the stability of production process Defining the correlation between identified strength parameters and the stability of production line allowed to examine the impact of plasticity margin for effectiveness and efficiency of the process. In mass production, each break in machine work results in loss of millions of units. The analysis allowed to compare the value of plasticity indicators of the raw tape deformability in the complex process of forming thin-walled cylindrical shell products and influence for increase the efficiency and reduction of defects.

Determination of Stoichiometry of GaAs Component in (Gaas)Ge Epitaxially Grown Thin Films by Electron Microprobe X-Ray Analysis

1990 ◽  
Vol 48 (2) ◽  
pp. 264-265
Author(s):  
D. R. Liu ◽  
S. S. Shinozaki ◽  
R. J. Baird
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Compound Semiconductors ◽  
Energy Dispersive Analysis ◽  
X Ray ◽  
Metastable Alloys ◽  
Lower Voltage

The epitaxially grown (GaAs)Ge thin film has been arousing much interest because it is one of metastable alloys of III-V compound semiconductors with germanium and a possible candidate in optoelectronic applications. It is important to be able to accurately determine the composition of the film, particularly whether or not the GaAs component is in stoichiometry, but x-ray energy dispersive analysis (EDS) cannot meet this need. The thickness of the film is usually about 0.5-1.5 μm. If Kα peaks are used for quantification, the accelerating voltage must be more than 10 kV in order for these peaks to be excited. Under this voltage, the generation depth of x-ray photons approaches 1 μm, as evidenced by a Monte Carlo simulation and actual x-ray intensity measurement as discussed below. If a lower voltage is used to reduce the generation depth, their L peaks have to be used. But these L peaks actually are merged as one big hump simply because the atomic numbers of these three elements are relatively small and close together, and the EDS energy resolution is limited.

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