Atlas Copco PowerMACS 4000, User Manual

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Tightening
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6.6.4 Monitoring Check
– Monitoring Yield point torque and angle
The monitoring checks Angle from Yieldpoint and Torque from Yieldpoint are described as one item since
their configuration is very similar.
User Interface:
Parameters: TC , NOS , INC , DIFF , Torque check Active , Torque check Fatal , YTH , YTL , Angle check
Active , Angle check Fatal , YAH , YAL
Function: Search for Yield point starts when the torque value has reached the trig level TC . From this
point the average torque is measured over NOS degrees (T
NOS
). This procedure is repeated
after each INC degrees.
When three or more T
NOS
values have been measure (that is after 3 NOS + 2 INC ) the
difference in average torque, T
DIFF
(k), is calculated as
T
DIFF
(k) = T
NOS
(k) - T
NOS
(k
– 2 )
This value corresponds to the current torque rate. Also, every time T
DIFF
is calculated its
maximum value, MaxT
DIFF
, is updated
MaxT
DIFF
(k) = MAX(T
DIFF
(k), MaxT
DIFF
(k
– 1))
The yield point is considered reached when T
DIFF
(k) < MaxT
DIFF
(k) * DIFF / 100