Page 75 - Robot Builders Source Book - Gordon McComb

3

Dynamic Analysis of Drives

In this chapter we shall discuss examples illustrating the operation time computa-
tion techniques for drives of different physical natures. We begin with the simplest—
a purely mechanical drive.

3.1 Mechanically Driven Bodies

The first case we shall consider in this section may be classified as a free-fall phe-
nomenon. This is the situation which occurs, for instance, when a stack of parts moves
vertically downwards in a magazine-type hopper (or dispenser). The simplest example
is presented in Figure 3.1, which shows a body falling from level I to level II through a
distance L Assuming that there is no resistance of any kind, we can write the follow-
ing expression for the time t required for this process:

Figure 3.2 shows a mechanism used in automatic machines (lathes) for feeding
rod-like material during processing. The weight M acts on the slider 2 via a cable I

FIGURE 3.1 Model of a free-falling body.
TEAM LRN
64