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The mode "Dynamic Limits" of the tolerance range monitoring of a ToolScope, is ideal for detecting tool breakages and tool overloads.

This monitoring procedure learns which signals are permissible for specific tools and workpieces. It learns how quickly the signal normally moves. Therefore, no tolerance ranges are learned, but rather the general characteristics of the signal.

An alarm is issued if a signal changes particularly quickly or significantly. As the torque of the motor that is driving the tool usually drops rapidly after a breakage, tool breakages are detected reliably.

The procedure works best with end mills and drills.

 

Configuring the dynamic monitoring procedure

 

1.6.1     Configurable parameters

 

Function name

Description

Activate offset compensation

The "Activate offset compensation" point can only be selected if the checkbox next to "Compensate signal offset" is set next to
"Service/ Settings / Monitoring / Channel 1". If this function is activated, the respective signal is set to zero when measuring starts. This is helpful when there is a fluctuating base load, as false alarms are avoided.

Deactivate tolerance ranges

If this function is activated, the green tolerance ranges are hidden. This is useful if you have redefined your monitoring under Maximum value / Wear limit / Missing limit.

Distance to upper limit

This value specifies the distance between the upper limit of the tolerance range in the Y direction and the signal. The value always relates to the distance that the monitoring would set by itself. A value of "1" causes the automatically calculated value to be applied exactly. Larger values increase the distance. Smaller values reduce it.

Distance to lower limit

This value specifies the distance between the lower limit of the tolerance range in the Y direction and the signal. The value always relates to the distance that the monitoring would set by itself. A value of "1" causes the automatically calculated value to be applied exactly. Larger values increase the distance. Smaller values reduce it.

Max. dynamic per second

This value specifies how quickly the tolerance range can move in the Y direction per second.

Delay time after the start of the process [s] / Delay time before the end of the process [s]

These values specify the time range after the start or before the end of the process during which the monitoring should not calculate any limits. If both values in this field are set to "0.0", both parameters are ignored.

CAUTION: As soon as values other than 0 are entered, ToolScope will act on the assumption that the processes will always be the same length. This is necessary to be able to use a delay time before the end of the process!

Safety distance from the signal in the X direction [s]

This value specifies the distance between the limits and the signal in the X direction.

Relearn; number of processes

As soon as the checkmark is set next to "Relearn; number of processes" and the process is observed the next time, the monitoring forgets the previous data and relearns the newly entered number of processes.

 

1.6.2     Special features of the dynamic monitoring procedure

The monitoring can be reconfigured in two ways. On the one hand, it is possible to use a (short) reference process to tell it which signals are permissible. On the other hand, it can observe a process over a given period of time and, after this time, independently begin monitoring.

In contrast to most other KOMET®  BRINKHAUS monitoring, relearning is carried out "online" here, if the process is very long. Figure 27 shows the result of a relearning process.

Standard dynamic monitoring display

 

The figure shows the monitored sensor signal in red and the limit values in green. The machine is stopped when these limit values are exceeded.

The green limit values act like a tolerance range, which the red sensor signal may not exit. The width of this tolerance range always remains constant. It continuously attempts to follow the sensor signal – but its maximum movement speed is restricted. This means that very rapid signal changes will result in an error.

The black limit value represents a maximum limit for the monitored signal. This limit remains constant.

During learning, the device fully automatically selects meaningful monitoring settings and writes them into the internal database.

Hint: To ensure that monitoring is configured correctly after this process, the period of time for learning must cover an operating process featuring above-average aggression. If the monitoring is relearned based on an operating process featuring below-average aggression, false alarms will occur.

In the "Configuration" view of the user interface, you can see which parameters have been selected.

Example: Monitoring a milling process

Scenario: Processes are to be monitored for tool breakage on a milling center.

  1. Use M and H commands to mark the processing to be sped up in your NC program, if required.
  2. Run your process once:

Learning a milling process

  1. Based on the observed process data, your device has now learned how the process should be monitored. Check visually that the monitoring configuration meets your requirements.

Channel configuration for the milling process

  1. Start your processes again.

Monitoring window for the milling process

 

Your device is now configured in such a way that it tolerates signal changes which occur with the speed designated as normal. The figure above shows an example of this. In red, it shows the torque of a motor driving a mill. The mill exits the material in the time range shown. The tolerance range, in which monitoring is performed, is drawn in green. In the figure above, the process is running normally. Signal rises and drops occur relatively slowly due to the physical conditions of penetrating the tool into a workpiece.

As soon as a mill breaks, the process force changes significantly faster than is possible during normal tool use. The figure below shows an example of a cutting process with the same tool, in the same workpiece material, when a tool breakage occurs.

 

The tool breaks during the process

 

As the signal falls significantly faster in the event of a breakage than was the case for previous material exits, the error is reliably detected. As this procedure is based on very basic, unchangeable physical principles, it is ideal for reliable breakage detection – without prior learning of a tolerance range.