HEIDENHAIN TNC 426 CB, Technical Manual

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6 – 154 HEIDENHAIN Technical Manual TNC 426, TNC 430
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280 470-xx You can define an angle limit for traverse at constant velocity. The size of the
angle depends on the machine drives:
7 7 7 7 Enter the permissible angle in MP7460.
Realistic input values: 5° to 15°
MP7460 functions without radius compensation at outside corners and with
radius compensation at inside corners. The parameters apply for operation
with both following error and feedforward control.
The contour is machined as shown here:
If you program M90, the tool velocity in following-error mode is kept constant
at corners without radius compensation. This causes a corner rounding that
varies with the feed rate (see User’s Manual).
If you program M112 or M124, defined arcs will be inserted at the corners
regardless of the feed rate (see User’s Manual). The rounding arcs generate
twice as many NC blocks, and the feed rate is now only limited by the radial
acceleration.
7
7 7
7
In MP7680 bit 7, specify whether the rounding arcs should always be
inserted or only when the acceleration from MP1060.x or MP1070 has been
exceeded at the corners.
7
7 7
7
With MP7680 bit 8, specify whether a rounding arc or a cubic spline is to be
inserted between lines during the M function M112. The cubic spline
produces an additional jerk reduction. But it takes more computing time than
an inserted arc. As of 280 476-xx the feed rate for arcs and splines is
reduced enough to prevent any excessive jerk. This does not apply if F MAX
is programmed.
MP7460
α
α =
Change of axis direction
s
a
= Servo lag
Axis standstill
Path when MP7460 <
α
Path when MP7460 >
α
s
a