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Functions, monitoring and protective functions
9.4 Extended functions
9.4.7.8
Traversing to fixed stop
Description
The "Travel to fixed stop" function can be used, for example, to traverse spindle sleeves to a
fixed stop against the workpiece with a predefined torque. In this way, the workpiece can be
securely clamped. The clamping torque can be parameterized in the traversing task (p2622).
An adjustable monitoring window for travel to fixed stop prevents the drive from traveling
beyond the window if the fixed stop should break away.
In positioning mode, traversing to a fixed stop is started when a traversing block is
processed with the FIXED STOP command. In addition to the dynamic parameters of
position, velocity, acceleration override and deceleration override, the required clamping
torque can be specified as task parameter (p2622) in this traversing block. From the start
position onwards, the target position is approached with the parameterized speed. The fixed
stop (the workpiece) must be between the start position and the braking point of the axis;
that is, the target position is placed inside the workpiece.
The preset torque limit is effective from the start, i.e. traversing to fixed stop also occurs with
a reduced torque. The preset acceleration and deceleration overrides and the actual speed
override are also effective. Dynamic following error monitoring (p2546) in the position
controller is not effective when traveling to the fixed stop. As long as the drive travels to the
fixed stop or is in fixed stop, the status bit r2683.14 (Travel to fixed stop active) is set.
Fixed stop reached
As soon as the axis comes into contact with the mechanical fixed stop, the closedloop
control in the drive raises the torque so that the axis can move on. The torque increases up
to the value specified in the task and then remains constant. The status bit r2683.12 (Fixed
stop reached) is set depending on the binector input p2637 (Fixed stop reached):
● If the following error exceeds the value set in parameter p2634 (fixed stop: maximum
following error) (p2637 = r2526.4).
● If the state is triggered externally by the signal at binector input p2637 (fixed stop
reached) (p2637 ≠ r2526.4)
In travel to fixed stop, the clamping torque or clamping force in the traversing block is
configured via the task parameter. It is specified in the units 0.01 Nm (rotary motor) or 1 N
(linear motor). The function module is coupled to the torque limit of the basic system via the
connector output r2686[0] (torque limit upper) or r2686[1] (torque limit lower), which are
connected to the connector input p1528 (torque limit upper scaling) or p1529 (torque limit
lower scaling).
The connector outputs r2686[0] (torque limit, upper) and r2686[1] (torque limit, lower) are set
to 100% when fixed stop is not active. During an active fixed stop, r2686[0] (upper torque
limit) or r2686[1] (lower torque limit) are evaluated as p1522/p1523 in such a way that a
limitation to the predefined clamping torque is applied.
684
Operating Instructions, 12/2018, A5E36652151A
Enclosed Drives
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