Axis Monitoring; Contour Monitoring; Contour Error; Following Error Monitoring - Siemens SINUMERIK 828D Function Manual

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A3: Axis Monitoring, Protection Zones

2.2 Axis monitoring

Axis monitoring

Contour errors are caused by signal distortions in the position control loop.

Signal distortions can be linear or nonlinear.

Linear signal distortions

Linear signal distortions are caused by:

Speed and position controller not being set optimally

Different servo gain factors of the feed axes involved in creating the path

With the same servo gain factor for two linear-interpolated axes, the actual position follows the set position

along the same path but with a time delay. With different servo gain factors, a parallel offset arises between

the set and actual path.

Unequal dynamic response of the feed drives

Unequal drive dynamic responses lead to path deviations especially on contour changes. Circles are distorted

into ellipses by unequal dynamic responses of the two feed drives.

Nonlinear signal distortions

Nonlinear signal distortions are caused by:

Activation of the current limitation within the machining area

Activation of the limitation of the set speed

Backlash within and/or outside the position control loop

When traversing a circular path, contour errors occur primarily due to the reversal error and friction.

During movement along straight lines, a contour error arises due to a reversal error outside the position

control loop, e.g. due to a tilting milling spindle. This causes a parallel offset between the actual and the set

contour. The shallower the gradient of the straight line, the larger the offset.

Nonlinear friction behavior of slide guides

In control engineering terms, traversing along a machine axis always produces a certain following error, i.e., a

difference between the set and actual position.

The following error that arises depends on:

Function Manual, 09/2011, 6FC5397-0BP40-2BA0

Basic Functions

Sinumerik 840d sl