Programming; Defining A Polynomial Function (Fctdef) - Siemens SINUMERIK 840D sl Function Manual

Additional properties
● An online tool offset can be activated for every grinding tool (tool type: 400 to 499) in each
channel.
● The online tool offset is generally applied as a length compensation. Like geometry and
wear data, lengths are assigned to geometry axes on the basis of the current plane as a
function of the tool type.
● The grinding spindle monitoring function remains active when an online tool offset is
selected.
Note
The online tool offset may only be used for grinding tools.
The offset always corrects the wear parameters of the selected length. If the length
compensation is identical for several cutting edges, then a chaining specification must be used
to ensure that the values for the 2nd cutting edge are automatically corrected as well.
If online tool offset is active in the machining channel, then the wear values for the active tool
in this channel may not be changed from the machining program or via operator inputs.
Modifications to the radius wear (P15) are not taken into account until the tool is reselected.
The online tool offset is also applied to the constant grinding wheel peripheral speed (GWPS),
i.e. the spindle speed is corrected by the corresponding value.
18.2.2

Programming

18.2.2.1

Defining a polynomial function (FCTDEF)

Certain dressing strategies (e.g. dressing roller) are characterized by the fact that the grinding
wheel radius is continuously (linearly) reduced as the dressing roller is fed in. This strategy
requires a linear function between infeed of the dressing roller and writing the wear value of
each length. The linear function is defined using the predefined procedure FCTDEF(...) for up
to third order polynomial functions.
Straight line equation
y = f(x) = a
a : Gradient of the straight line, with a
1
a : Shift of the straight line along the X axis with a
0
Extended Functions
Function Manual, 10/2015, 6FC5397-1BP40-5BA3
+ a *x
0 1 1
W4: Grinding-specific tool offset and tool monitoring
= Δx / Δy
1
= -a1 * X
0 V
18.2 Online tool offset
857