( 5 ) Applications of
NC/CNC machine tools
CNC was initially applied to metal working machinery:
Mills, Drills, boring machines, punch presses etc and
now expanded to robotics, grinders, welding machinery,
EDM's, flame cutters and also for inspection equipment
etc. The machines controlled by CNC can be classified
into the following categories: CNC mills and machining
centres.
- CNC lathes and turning centers
- CNC EDM
- CNC grinding machines
- CNC cutting machines (laser, plasma,
electron, or flame)
- CNC fabrication machines (sheet metal
punch press, bending machine, or press brake)
- CNC welding machines
- CNC coordinate measuring machines
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CNC Coordinate Measuring Machines:
A coordinate measuring machine is a dimensional measuring
device, designed to move the measuring probe to determine
the coordinates along the surface of the work piece. Apart
from dimensional measurement, these machines are also
used for profile measurement, angularity, digitizing or
imaging.
A CMM consists of four main components: the machine, measuring
probe, control system and the measuring software. The
control system in a CMM performs the function of a live
interaction between various machine drives, displacement
transducers, probing systems and the peripheral devices.
Control systems can be classified according to the following
groups of CMMs.
1. Manually driven CMMs
2. Motorized CMMs with automatic probing systems
3. Direct computer controlled (DCC) CMMs
4. CMMs linked with CAD, CAM and FMS etc.
The first two methods are very common and self explanatory.
In the case of DCC CMMs, the computer control is responsible
for the movement of the slides, readout from displacement
transducers and data communication. CMM are of different
configurations-fixed bridge, moving bridge, cantilever
arm figure 21.5(a), horizontal arm and gantry type CMM
as shown in figure 21.5(b).
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/fig-6.gif)
Figure 21.5(a) Cantilever type CMM
/fig-7.gif)
Figure 21.5(b) Gantry type CMM
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