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free .net barcode reader library Gas Lubricated Bearings in Software
Gas Lubricated Bearings Recognizing Data Matrix ECC200 In None Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications. Draw ECC200 In None Using Barcode generator for Software Control to generate, create Data Matrix ECC200 image in Software applications. Fig 728: The relationship of stiffness with air pressure [25] Data Matrix ECC200 Recognizer In None Using Barcode decoder for Software Control to read, scan read, scan image in Software applications. DataMatrix Printer In Visual C# Using Barcode creation for Visual Studio .NET Control to generate, create DataMatrix image in .NET framework applications. Fig 729: A Toshiba work spindle [26] Printing Data Matrix 2d Barcode In .NET Framework Using Barcode generator for ASP.NET Control to generate, create Data Matrix 2d barcode image in ASP.NET applications. DataMatrix Drawer In VS .NET Using Barcode creation for Visual Studio .NET Control to generate, create Data Matrix 2d barcode image in .NET applications. axial stiffness of 1,140 N/ m [27] The Precitech highspeed airbearing spindle has a speed range of 10 10,000 rpm with a load capacity of 18 kg (40 lb) and an axial stiffness of 31 N/ m (175,000 lb/in) [28] Figure 732 shows the schematic diagram of a work spindle and a grinding spindle in a Moore ultraprecision machine An air turbine drives the grinding spindle shown in Draw Data Matrix In Visual Basic .NET Using Barcode drawer for VS .NET Control to generate, create Data Matrix image in .NET framework applications. UCC  12 Encoder In None Using Barcode generator for Software Control to generate, create EAN / UCC  13 image in Software applications. Precision Engineering
Barcode Drawer In None Using Barcode printer for Software Control to generate, create barcode image in Software applications. Paint Code 3/9 In None Using Barcode printer for Software Control to generate, create Code 3 of 9 image in Software applications. Fig 730: A Moore aerostatic work spindle for ultraprecision machines [27] Make Barcode In None Using Barcode encoder for Software Control to generate, create bar code image in Software applications. Encoding DataMatrix In None Using Barcode creator for Software Control to generate, create ECC200 image in Software applications. Fig 731: A Precitech Nanoform 200 work spindle [28] Fig 732: Front view of machine work [29] Leitcode Drawer In None Using Barcode creator for Software Control to generate, create Leitcode image in Software applications. Generate EAN 128 In Visual C#.NET Using Barcode creation for VS .NET Control to generate, create UCC.EAN  128 image in .NET framework applications. Figure 733 It has a maximum speed of 70,000 rpm [29] Due to the high stiffness and rigidity required, the grinding spindle is also supported by air bearings Passive air bearings are used in spindles for woodworking The spindle shown in Figure 734 basically consists of a hollow shaft (1), journal bearings (2 and 10), thrust bearing (4) and an 8 kW asynchronous motor The spindle is capable of 36,000 rpm The runout at 0 rpm is less than 1 m in both the axial and radial directions, whereas the stiffness is 100 N/ m in the axial direction and around 40 N/ m in the radial direction [4] Barcode Generator In None Using Barcode encoder for Office Word Control to generate, create barcode image in Office Word applications. Generating Code 128 Code Set B In Java Using Barcode generation for BIRT Control to generate, create ANSI/AIM Code 128 image in Eclipse BIRT applications. 738 Mathematical Approximation of Aerostatic Bearings
GS1  13 Generation In ObjectiveC Using Barcode generation for iPad Control to generate, create GTIN  13 image in iPad applications. Decode USS Code 128 In Java Using Barcode scanner for Java Control to read, scan read, scan image in Java applications. As in hydrostatic bearings, the pressure and load capacity of the aerostatic bearing can be roughly
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Fig 733: A Moore air bearing grinding spindle attachment [29] approximated by a onedimensional flow (Figure 735) Further design details will be discussed based on an example in the next section It may be beneficial to compare the pressure profile for the two Fig 734: A spindle with passive air bearings for woodworking [4] types of bearings In the half station, feeding aerostatic bearing where only one row of jet is used at the middle of the bearing, the pressure profile is of a triangular shape However, if two rows of jets are used either at the onequarter or the oneeighth feeding station, the pressure profiles will overlap resembling that of the hydrostatic bearing (Figure 736) Precision Engineering
Fig 735: The load and pressure relationship based on a onedimensional flow
739 Theory of Aerostatic Lubrication
Most of the mathematical analysis behind aerostatic lubrication is based on fluid mechanics This information is of little practical importance for designers For this reason, only the basic theory is illustrated in order to maintain the simplicity of the design Gas flow lines
Pressure distributions (a) Axial flow model (b) Real bearing
Fig 736: The theoretical and actual pressure distribution [3] Gas Lubricated Bearings
The flow in the clearance of gas bearings is usually laminar with pressure losses mainly due to the viscous shear in the air film The study of this effect is assumed as flow between parallel plates However, it is different for rectangular slots and circular plates which are mainly applied for journal and thrust bearings, respectively [3] A number of assumptions listed next are made to simplify the analysis and to apply the Navier Stokes equation: Inertia forces due to acceleration can be neglected compared with frictional forces due to viscous shearing Laminar flow conditions exist at all points in the gas film Pressure is constant over any section normal to the direction of flow There is no slip at the boundaries between the fluid and the plates The complete analysis begins with the basic Navier Stokes equation which is given as 1 P 2u = 2 x y
where u is the velocity of the gas at any point, P the pressure, the viscosity of the gas, g the gravitational field and h is the thickness of the gas film By applying boundary conditions as in Figure 737 and the principle of the conservation of mass, expressions representing the pressure and mass flow can be obtained Detailed steps can be obtained from Design of Aerostatic Bearings by JW Powell [3] and any fluid mechanics book that deals with the fundamentals Fig 737: Munson et al s illustration of flow between two stationary parallel plates [30] The load capacity and the stiffness of an aerostatic journal bearing depend upon the design value of the gauge pressure ratio, Kgo, which varies with the eccentricity ratio as shown in Figure 76 The optimum value of Kgo for various eccentricity ratios as recommended by Shires is shown in

