Path Machining

Layer and deep feed machining during path-controlled ultrasonic lapping. (From Hilleke, M., Dissertation RWTH Aachen, 1998. With permission.) 

Die-sinking the counterpart to desired depth and subsequent running over the required contour (deep feed machining). 

Slow die-sinking of the counterpart at a high cross-feed speed, so that the counterpart reaches the desired depth of cut in several runs (layer machining) (Noelke, 1980 Hilleke, 1998). 

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A convenient method of carrying out such a galvanic test in the laboratory has been described by Wesley in which the vertical circular-path machine is used. Each assembly includes two pairs of dissimilar metals—one pair coupled galvanically while the other pair is left uncoupled in order to determine the normal corrosion rates under the same environmental conditions. The type of motion provided (specimens moving in a vertical circular path) enables electrical connections to be made without mercury cup or commutator and the leads can be connected to a calibrated resistance for current measurements attached to the specimen carrier. 

Two types of ultrasonic machining are currently used ultrasonic sink and ultrasonic path machining. In the case of sink machining the ablation rate is highest in front of the tool. At the sides of the tool the ultrasonic amplitude in normal direction to the surface is rather small, which results in a rolling of the abrasive particles so that the particles cause no direct impact in the work piece. A review of ultrasonic machining can be found in the literature [517]. 

Improved materials, coatings, and cooling techniques permit newer machines to operate at higher turbine inlet temperatures, yielding both increased output and efficiency. Further efficiency gains result from improved aerodynamics in the hot gas path, compressor, and turbine sections. Use is also made of variable inlet guide vanes (IGV). 

De Laval Extractor (Palmqvist and Beskow, U.S. Patent 3,108,953, 1959) This machine contains a number of perforated cylinders revolving about a vertical shaft. The liquids folfow a spiral path about 25 m (82 ft) long, in countercurrent fashion radially, and mix when passing through me perforations. There are no published performance data. 

This chapter examines the overaii performance characteristics of compressors and turbines. This materiai is presented here to famiiiarize the reader with the behavior of these machines, ciassified under the broad term tur-bomaciiinery. Pumps and compressors are used to produce pressure turbines produce power. These machines have some common characteristics. The main eiement is a rotor with biades or vanes, and the path of the fluid in the rotor may be axiai, radiai, or a combination of both. 

Figure 5-17 is a section of a typical multistage compressor, which should aid the reader in following the flow path through the machine. 

Impeller construction for the cover-disk style impeller historically has been by built-up construction and welding. The traditional method uses die formed blades (see Figure 5-34). More recently, with the increased use of 5-axis milling, blades have been milled integrally with the hub disk. This alternate construction method is somewhat more costly because of the machining but produces a more accurate and repeatable gas path, which offsets the added expense (see Figure 5-35). Cover disks arc w ddcd to the blades to complete the milled impeller. Physical prop-... 

Friction (or, if within the refrigerant path, as in hermetically sealed or semi-hermetic machines, the whole of the... 

Figure 32.16 presents on the basis of the characteristic number the typical impeller profiles, velocity triangle shapes, and characteristic curves to be expected from the machine flow paths shown. This indicates the use of the number as a design tool for the pump engineer. 

Polar wrap machine can be used where geodesic (non-slipping) path is in a plane. 

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