Siemens SINUMERIK 828D Manual page 82

3.5
82
Important functions for 3- to 5-axis machining
Effect of the tool length on the machine movement
To investigate the effect of the tool length on the machine movement, let us consider a further
example. The base circle of the half sphere shown in the graphic is to be machined with an
inclined tool.
Rotary axis movement and tool orientation
The rotary axes in 5-axis machines are used to enable the various orientations of the tool relative
to the workpiece. The movement of a rotary axis normally not only changes the tool orientation,
but also the position of the tool tip in relation to the workpiece surface if this is not prevented by a
suitable mechanism.
.
Tool tip moves
1
Example shows that the movement of the A axis not only changes the tool orientation to the
1
workpiece. At the same time, the tool tip moves in space, a circular path in the Z-X plane in our
example. This is an unwanted side effect.
Generally, the movement shown in
linear axes ensure that the tool tip is fixed in space during rotary axis movements.
© Siemens AG All rights reserved SINUMERIK, Manual, Mold-Making with 3- to 5-Axis Simultaneous Milling
In the graphic, you can see that different tool
lengths result in different machine
movements. To machine the circle on the
lower part of the half sphere, traversing must
be performed in a circle in the X-Y plane and
also the C axis must be rotated through 360°
during the circular movement. Whereas the
circle for the tool tip always remains the same
size irrespective of the tool length, the circle
that the machine axes must describe
increases with the tool length. This is indicated
by the two red circles that are produced with
different tool lengths.
It is clear that when programming machine
axis positions, a different program must be
created for each tool length, while the
movement of the tool tip always remains the
same.
Tool tip fixed in space
2
is desirable, in which compensatory movements of the
2