Spiral screw

Figure 12-110A. A typical cross-section showing the spiral screw rotors, lubrication system, and other details of internal construction. (Used by permission 1961. Roots Division, Dresser Industries, Inc.)...

Unfortunately sometimes a new design concept is not accepted or may simply be ahead of its time. In 1483 Leonardo da Vinci designed what he called a spiral screw flying machine. In 1942 Igor Sikorsky developed the... 

CA 69, 4112k (1968) [Continuous mixing of AN-liquid hydrocarbon (such as fuel oil), using a spiral screw conveyor is described]... 

Spiral screws usually run at 1800-3600 rpm. Their capacity ranges up to 12,000 CFM or more. Normal pressure boost is 3-20 psi, but special units can boost pressures by 60-100 psi. In vacuum service they can produce pressures as low as 2 psia. Some other performance data are shown with Figure 7.19(d). 

Fig. 30. Diagram of a nitrator with a spiral screw stirrer.

For liquids of low viscosity a spiral screw stirrer may be used (Fig. 30). Circulation can be facilitated by surrounding the stirrer (I) with a sheet metal cylinder... 

Extrusion is the process of heating practically only TPs that may be in the shape of powders, beads, flakes, pellets, or combinations of these forms. This plastic enters the extruder s hopper. The extruder utilizes a plasticator [spiral screw that rotates within a heated barrel (cylinder)] to melt the plastic (Chapter 3). The melted plastic is then forced through a die to produce the desired continuous product shape. Figure 5.1 shows a very simplified schematic of the extrusion process. Information on dies (mono-layer and coextruded) used in extrusion is in Chapter 17. 

The example shown in Figure 4.35 is a tool electrode in the form of a spiral screw. It requires a special controller. The workpiece is clamped vertically and processed in theA" or y direction. Another possibility is to incorporate a spiral screw or a gear tooth in a rotated way into a tool, as shown in the example in Figure 4.36. 

Fig. 12.65a-f. Acetabular cup for hip replacement, a Photograph, b standard radiograph and c in vitro US appearance of an acetabular spiral screwed cup. US depicts the cup as a hyperechoic structure with reverberation artifact characterized by a series of external teeth arrowhead), d-f Schematic drawings of a sagittal view through the anterior hip illustrate d a normally positioned cup, e,f an anterior protruding cup resulting in e iliopsoas bursitis asterisks) and f tears of the undersurface of the iliopsoas muscle arrowheads). A, native acetabulum Ac, acetabular cup H, head of the prosthesis N, neck of the prosthesis F, femoral bone... 

---