Function Description - Siemens SINUMERIK 840D sl Function Manual

TE1: Clearance control - 840D sl only
15.1 Brief description
15.1.2

Function description

Laser cutting technology is used as an example for the detailed description of the "clearance
control" functionality.
Laser cutting
During laser cutting, a divergent parallel laser beam is directed across a fiber-optic cable or
via a mirror to a light-collecting lens mounted on the laser machining head. The collecting lens
focuses the laser beam at its focal point. Typical focal lengths are from 5 to 20 cm.
The position of the focal point in relation to the workpiece is an extremely critical process
parameter in laser cutting operations and must be kept constant within a tolerance of ≤100 µm.
The distance between the focal point and the workpiece, which is also a key process variable,
is usually measured by means of a high-speed capacitive clearance sensor. The analog output
voltage of the clearance sensor is approximately proportional to the distance between the
sensor and the workpiece surface.
The output voltage of the clearance sensor is transmitted as a digital input value via an analog
I/O module to the control where, in the event of deviations from the setpoint clearance, it
generates an additional velocity setpoint for the machining head motion axes.
System overview (840D sl)
An overview of the system components required for clearance control in conjunction with
SINUMERIK 840D sl is provided in the following diagram.
Figure 15-1
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System components for clearance control with SINUMERIK 840D sl
Function Manual, 01/2015, 6FC5397-2BP40-5BA2
Special functions