Compensation At The Outside Corners (G450, G451) - Siemens SINUMERIK 840DE Programming Manual

Tool offsets

8.10 Compensation at the outside corners (G450, G451)

Description of KONTC and KONTT
The continuity conditions are observed in all three axes. It is therefore permissible to
program a path component perpendicular to the offset plane simultaneously.
Exception:
KONTT and KONTC are not available in the 3D variants of the tool radius compensation
(CUT3DC, CUT3DCC, CUT3DF).
If they are programmed, the control switches internally to NORM without an error message.
Difference between KONTC and KONTT
This diagram shows the differences in approach/retract behavior between KONTT and
KONTC. A circle with a radius of 20 mm about the center point at X0 Y-40 is compensated
with a tool with an external radius of 20 mm. The tool center point therefore moves along a
circular path with radius 40 mm. The end point of the approach blocks is at X40 Y30. The
transition between the circular block and the retraction block is at the zero point. Due to the
extended continuity of curvature associated with KONTC, the retraction block first executes a
movement with a negative Y component. This will often be undesired. This response does
not occur with the KONTT retraction block. However, with this block, an acceleration step
change occurs at the block transition.
If the KONTT or KONTC block is the approach block rather than the retraction block, the
contour is exactly the same, but machined in the opposite direction.
8.10 Compensation at the outside corners (G450, G451)
Function
G450/G451 defines the following:
On the one hand, the approach path for active KONT and the approach point behind the
contour (see section "Contour approach and retraction").
On the other hand, the corrected tool path when traveling around outside corners.
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Programming Manual, 10.2004 Edition, 6FC5 298-7AB00-0BP1
Fundamentals