December 2001 Contouring Behavior 6 – 153
6.10.2 Contour Velocity at Corners
As of NC software
280 472-xx
To comply with a defined tolerance, the TNC can reduce the tool velocity
before reaching machining corners, line-to-arc transitions and arc-to-arc
transitions. The control can react to a potential violation velocity tolerance up
to 128 blocks in advance. This feature is known as “look ahead”:
7
77
7 Define the permissible tolerance for contour transitions in MP1096. The
larger the tolerance, the greater the tool velocity.
The user can overwrite this tolerance with Cycle 32, “Tolerance.”
Jerk limitation (See “The Interpolator” on page 6 – 113) and nominal-position-
value filter enable the TNC to machine 3-D surfaces at high speed.
Prerequisite: The contour must be described with short line segments.
To ensure that cutter-compensated outside corners remain exact, a spline
must be inserted into the cutter midpoint path instead of a transitional arc. A
spline also has the advantage of reducing the jerk:
7
77
7 Enter MP7680 bit 10 = 1.
MP1096 Tolerance for contour transitions
Input: 0: No nominal position value filter
0.001 to 3.000 [mm]: Permissible tolerance at contour
transitions
MP7680 Machine parameter with multiple function
Format: %xxxxxxxxxxxxx
Input: Bit 10 – Cutter-radius-compensated outside corners:
0: Insertion of a circular arc
1: Insertion of a spline curve
Proposed input value: %xx1xxxxxxxxxx
Bit 11 – Reserved
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