Siemens SINUMERIK 828D Manual page 94

3.5
Important functions for 3- to 5-axis machining
Comparison of ORIVECT and ORIAXES
To illustrate the differences more clearly, let us consider the two most commonly used cases
ORIVECT and ORIAXES. As already mentioned, ORIAXES is the standard interpolation type
that is most commonly used. The rotary axes are interpolated linearly synchronous to the
movement of the tool tip. Let us consider the following situation to illustrate this type.
The following figure shows the movement of a fork head machine with C and A axes along an NC
block.
We will begin at the start of the block with position P1, the tool vector t1 and the corresponding
rotary axes positions C1 and A1. The position, the tool vector and the rotary axes positions at the
end of the block are specified with P2, t2, C2 and A2. For the interpolation of the tool tip with the
programmed velocity, the distance to the end point is divided into sections of equal size, whose
length ΔS corresponds to the interpolation cycle and the programmed feedrate. The increment is
ΔS = VT, whereby V is the velocity and T the interpolation cycle time. At constant velocity, the
entire traversing distance D between P1 and P2 is divided into nine equidistant interpolation
increments.
In the same way with ORIAXES, the difference of the rotary axis positions C2-C1 and A2 - A1 is
divided into 9 equidistant increments C and A. This means that the curve of the rotary axis
positions linearly follows the path motion.
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