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ComputerAided_Design_Engineering_amp_Manufactur.pdf

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FIGURE 4.11(c) Inspection results for a mold plate.<br />

pins on the mold base. Following the inspection planning procedures, the measurement operations are<br />

performed and the errors are calculated. Figure 4.11b shows the error analysis of the sculptured surface:<br />

the form error is found as 0.423 mm, with the maximum error of 0.207 mm (under cut) and the minimum<br />

error of �0.212 mm (over cut). Figure 4.11c depicts the inspection results for the mold base feature,<br />

giving squareness, parallelism, and the flatness errors. Figure 4.11d shows the inspection results of a<br />

pocket for the cavity block, giving the straightness, parallelism, squareness error, and dimensional accuracy<br />

of the pocket.<br />

A Turbine Blade Having Very Thin Features<br />

The CAD data base of a turbine blade is assessed and the geometric features of the blade are reconstructed.<br />

Generally, a turbine blade consists of an airfoil fairing in the direction of air flow, a spanwise<br />

fairing in the perpendicular direction, and a base block as the reference. A 3-D representation of a<br />

turbine blade is shown in Figure 4.12a. Each airfoil section is then stacked in the spanwise direction<br />

with respect to the stacking point, where the stacking point is the reference point for generating the<br />

momentum of air flow. As shown in Figure 4.12b, the airfoil section is usually composed of several<br />

features: pressure curve, suction curve, leading edge, trailing edge, etc. The pressure/suction curves<br />

are generally modeled as the smooth spline curves, and the leading/trailing edges are modeled as<br />

circles, where the edges have very small radius compared to the pressure/suction curves. After the

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