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5 Programming: Tools
5.4 Three-Dimensional Tool
Compensation
The TNC can carry out a three-dimensional tool compensation (3-D
compensation) for straight-line blocks. Apart from the X, Y and Z
coordinates of the straight-line end point, these blocks must also
contain the components NX, NY and NZ of the surface-normal
vector (see figure below right). The straight-line end point and the
surface normal vector are calculated by a CAD system. The 3-D
compensation enables you to use tools that have other dimensions
than the ones you originally programmed.
Tool shapes
The available tool shapes (see the upper two illustrations at right)
are defined by the tool radii R and R2:
TOOL RADIUS: R
Distance from the tool center to the tool circumference
TOOL RADIUS 2: R2
Radius of the curvature between tool tip and tool circumference.
The ratio of R to R2 determines the shape of the tool:
R2 = 0 End mill
R2 = R Toroid cutter
0 < R2 < R Spherical cutter
These data also specify the coordinates of the tool datum P
T
.
You enter the values for TOOL RADIUS and TOOL RADIUS 2 in the
tool table.
Surface-normal vectors
Definition of surface-normal vectors
A surface-normal vector is a mathematical quantity with
■ a magnitude
here: the distance between the workpiece surface and the tool
datum P
T
, and
■ a direction
End mill and radius mill: perpendicular to the workpiece surface
to be machined, toward the tool datum P
T
Toroid cutter: through P
T
‘ or P
T,
respectively.
The magnitude and direction of a surface-normal vector is
determined by the components NX, NY and NZ.
5
.4
Thr
ee-Dim
ensional T
ool Compensation
P
T
R R R
R2
P
T
P
T
R2
P
T
'
Z
Y
X
P
T
NZ
P
NX
NY
Fkap5.pm6 30.06.2006, 07:03 82
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