Page 33 - Robotics Designing the Mechanisms for Automated Machinery

22 Introduction: Brief Historical Review and Main Definitions

and withdrawal distances and by increasing the speeds of approach and withdrawal.
Similarly, the transportation of a part from a drilling position to, say, a threading posi-
tion is an idle stroke. In principle, neither the threading process nor the drilling oper-
ation requires this transportation component, which appears only as a result of the
chosen design concept.
Let us denote the idle and auxiliary time losses r, then

where Tis the pure processing time.
From Equation (1.1) we obtain:

We can now introduce the concept of a processing efficiency coefficient rj l in the form

A modification of the composition discussed above may also be used. In this mod-
ification the blocks 1, 2, 3, and 4 are partly or completely placed inside the rotating
table, as shown in Figure 1.22. This modification is more convenient because it facili-
tates free approach of the items to the tools and to all the devices, while the devices
do not obscure the working zones. However, the drives, the kinematics, and the main-
tenance of this type of composition are more complicated. Another possibility is to
build the transporting device 5 in a linear shape as a sort of a conveyer, as is shown in
Figure 1.23. In this configuration the devices 1,2,3, and 4 are located on the same side
of the conveyer (although there is no reason that they should not be located on both

FIGURE 1.22 Circular
configuration for an automatic
tool with partial internal
location of blocks.