cork removers

Figure 2.9 shows examples of

using these worlung principles. All are described
by the function structure sketched in the upper part of Figure 2.10: create a force, transmit a
force, apply force to cork. They differ in the working principle by which these functions are
achieved, as indicated in the lower part of Figure 2.10. The cork removers in the photos combine
working principles in the ways shown by the linking lines. Others could be devised by making
other links.
Figure 2.11 shows embodiment sketches for devices based on just one concept -that of axial
traction. The first is a direct pull; the other three use some sort of mechanical advantage -levered
pull, geared pull and spring-assisted pull; the photos show examples of all of these.
The embodiments of Figure 2.8 identify the functional requirements of each component of the
device, which might be expressed in statements like:
.a light lever (that is, a beam) to carry a prescribed bending moment;
.a cheap screw to transmit a prescribed load to the cork;
.a slender elastic blade which will not buckle when driven between the cork and bottleneck;
.a thin, hollow needle strong enough to penetrate a cork;
and so on. The functional requirements of each component are the inputs to the materials selection
process. They lead directly to the property limits and material indices of Chapter 5: they are the
first step in optimizing the choice of material to fill a given requirement. The procedure developed
there takes requirements such as 'light strong beam' or 'slender elastic blade' and uses them to
identify a subset of materials which will perform this function particularly well. That is what is
meant by design-Ied material selection.

Bagikan Artikel ini