RTC
®
5 PC Interface Board
Rev. 1.9 e
8 Advanced Functions for Scan Head and Laser Control
167
innovators for industry
8.4 Wobbel Mode
The wobbel mode allows varying the line width for
laser marking.
Basically, an ellipse-shaped motion is added to the
regular, linear movement of the output position,
resulting in a spiral movement of the laser focus in
the image field. Alternatively, a combination with a
figure-of-8 (horizontal or vertical to the direction of
motion) can be activated.
A broadening of the original line is obtained by
choosing suitable values for the transverse and longi-
tudinal amplitudes and the frequency of the wobbel
movement. With figure-of-8s, broader mid-line
processing can be achieved via appropriate
parameter values. If the specified transverse and
longitudinal amplitudes are identical, then the
wobbel shape remains stationary in space; otherwise
the orientation of the wobbel shape follows the
current direction of motion.
During Processing-on-the-fly correction via the
McBSP or encoder interfaces where the scan head
only compensates differences between actual
external movements and intended total motion (see
chapter 8.7.2 "Compensation of Linear Movements",
page 179
, a slight jitter in the direction of galva-
nometer motion might occur, particularly during
exact external path motions. Here, the wobbel
movement superimposed onto the direction of
motion will correspondingly jitter, too. You can avoid
such jitter by specifying a fixed (instead of the
momentary) direction of motion for the wobbel
shape via the
list command.
For optimum marking results, the wobbel frequency
should be appropriate for the specified marking
speed. In some cases it can be useful to adjust the
marking speed when the wobbel mode is used.
, the wobbel
start point is always set for the same value relative to
the vector/arc startpoint and direction. The Wobbel
phase will then be continued both within an uninter-
rupted polyline (including arcs) and after interrup-
tions (e.g. a jump command) until
are called again.
Refer to the command
for further details.
For many welding applications, the default set of
“classic” wobbel shapes (circle, ellipse, sine, figure-8)
does not produce optimal (smooth) results in the
area of the weld seam. With ellipses, for example,
high-speed motion occurs parallel to translation
movements and low-speed motion occurs in the
opposing direction, resulting in uneven energy depo-
sition. The command
define a wobbel shape customized for your appli-
cation, consisting of up to 512 piecewise linear
sections, while also specifying variation of laser
power along that shape (also see
). This function can’t be used
together with the Softstart function nor with auto-
matic or vector-based laser control.
55
Principle of the wobbel mode
above:
circular wobbel
middle: ellipse-shaped wobbel
below:
figure-of-8 wobbel (horizontal 8)
