Mitsubishi Electric MELSERVO-J5 User Manual page 286

Outline [A]
The belt diagnosis function estimates the tension deterioration of the belt connected to the servo motor by using the friction
value of the servo amplifier internal data. A belt failure can be predicted based on the tension deterioration of the belt. Also,
the timing of belt re-tensioning can be determined. Note that belt breakage cannot be predicted with the belt diagnosis
function.
Belt tension dropping diagnosis
Friction threshold
Warning
[%]
occurrence
Belt tension [N]
The belt diagnosis function includes the following two functions:
■Friction failure prediction function
The friction failure prediction function predicts a failure of the equipment from the increase/decrease in the static friction
estimated by the friction estimation function. If a failure of the equipment is predicted, [AL. 0F7 Machine diagnosis warning]
occurs. The threshold of [AL. 0F7 Machine diagnosis warning] can be set automatically, and therefore this function is easier to
use than the belt tension deterioration prediction function. In order for the static friction failure prediction function to detect the
increase/decrease of the static friction, the accuracy of belt tension deterioration is low, and the initial stretch of the belt may
trigger [AL. 0F7 Machine diagnosis warning].
■Belt tension deterioration prediction function
For the belt tension deterioration prediction function, [AL. 0F7 Machine diagnostic warning] occurs when the belt tension that
is estimated from the servo amplifier internal data is equal to or lower than the input threshold of the belt tension servo
parameter. Although the relationship between the belt tension and the static friction needs to be input with servo parameters,
this function can improve the accuracy in detection of the belt tension deterioration by estimating the belt tension and
outputting [AL. 0F7 Machine diagnosis warning].
Differences between the static friction failure prediction function and the belt tension deterioration function are shown on the
following table.
Item
Determination criteria
Threshold setting
Input required servo
parameter
Belt tension deterioration
detection accuracy
4 APPLICABLE FUNCTIONS
284
4.5 Machine diagnosis
Friction failure prediction function
Static friction
Automatic setting possible
[Pr. PF51.5 Static friction failure prediction warning selection]
[Pr. PF53 Failure prediction - Servo motor total travel distance]
Low
Encoder
Belt-driven equipment
Reduced belt tension
Belt tension deterioration prediction function
Belt tension
Manual setting
[Pr. PF71.0 Belt tension deterioration prediction function
selection]
[Pr. PF72 Belt tension on installation]
[Pr. PF73 Belt tension when extended]
[Pr. PF74 Static friction during installation]
[Pr. PF75 Static friction when extended]
[Pr. PF76 Belt tension irregular threshold]
High
Pulley