General Functionality - Siemens SINUMERIK 840D sl Function Manual

5.2.2

General functionality

Curve tables
A functional relation between a command variable "master value" and an abstract following
value is described in the curve table.
A following variable can be assigned uniquely to each master value within a defined master
value range.
Curve segment
The functional relation can be subdivided into separate sections of the master value axes,
called curve segments.
Within a curve segment, the relation between the master value and following value is
generally described by a polynomial up to the third order. Polynomials up to the 5th degree
are also permissible.
References:
/PGA/ Programming Manual Work Preparation
Curve segments are used if:
• Polynomes or circles are programmed
• Spline is active
• Compressor is active
• Polynomials or circles are generated internally (chamfer/rounding, approximate
positioning with G643, WRK etc.)
Tool radius compensation
Curve tables are available in which it is possible to specify the tool radius compensation in the
table definition even if polynomial blocks or blocks with no motion for an axis, or jumps for the
following axis, occur in the curve table (G41/G42/G40 in the table definition).
The equidistant curve (tool center point path of tool radius compensation) of a curve
consisting of polynomials can no longer be displayed exactly using polynomials. The
associated curve tables must be approximated stepwise, using polynomials in this case. This
means that the number of segments in the curve table no longer matches the number of
programmed segments. The number of segments required for the curve table is defined by
the bend of the curve. The larger the curvature for the programmed curve, the more segments
are required for the curve table.
On account of tool radius compensation for curve tables, more memory may be required.
Selection option of the memory type should not produce shortage of static NC memory.
Special Functions
Function Manual, 09/2011, 6FC5397-2BP40-2BA0
M3: Coupled axes
5.2 Curve tables
213