Reversing measuring location

Description

A reversing measuring location is a measuring location that the material passes through completely multiple times, each time in the opposite direction. This means that reversing partial sections of a product cannot currently be mapped with ibaQDR.

Internally, each pass is stored separately as though there were multiple measuring locations passed through in turn. Therefore for licensing purposes, the configured maximum number of passes is taken into account in the number of measuring locations.

To correctly map the data, the head and tail of the length-based measuring series are reversed at every second pass (even pass numbers).

Typical applications

• Reversing stand (with material elongation)

• Edger-rougher combination (with material eleongation)

• Coil box (without material elongation)

Example of a roughing stand in a hot rolling mill (actual data):

The following figure shows the associated signal progression for the three passes:

Measuring location properties

Name, Tracking ID, Enable, Maximum elongation, Entry and Exit length like for standard measuring location.

The value for Maximum elongation applies to each pass and is not a total over all passes.

Head cut/Tail cut

In case of one or more crop cuts at strip head (head cut) or strip end (tail cut) after this measuring location, the length value of the strip needs to be corrected by the cut length. This ensures the correct length-related mapping of the measured values for this and the following measuring locations.

Select here the signals which transmit the total cut length of head and tail cuts. If there is no shear behind this measuring location, select "No cut".

The following figure shows an example of a rougher mill with a head cut and a tail cut between the first and second pass. The red and the blue curve show the cut lengths. Consequently, the entry length (green curve) of the second pass equals the exit length (magenta curve) of the first pass reduced by the cut lengths.

Pass number

Select an analog signal that counts the passes. The signal should be provided by the line control or material tracking system.

If no material is present, the value should be 0. For the first pass the value should be 1, for second pass 2, etc.

Last pass

Here, you can select a digital signal that indicates when the last pass is running. This setting is optional. You only need the signal if a product file for the tracked part (e.g. entry coil) is to be generated at the reversing measuring location.

If the signal is to be used, it must be log. 1 (TRUE) for the entire duration of the last pass.

Maximum number of passes

Set the maximum number of passes n to be completed on the line. This value n specifies how many instances of the measuring location are created in the product file. At each pass, the signal values are saved to an instance. Each of these instances is automatically given a designation containing the pass number. The instance n always corresponds to the last pass, instance n-1 the penultimate pass, etc.

If more passes are made than the maximum number n set here, only the data for the last n passes is saved in the product file.

If fewer passes than the set maximum number n are made, only the last passes or the last instances are populated and the first passes contain no data.

Note
	Please note in this context the setting for Pass numbering in the basic QDR data store settings. Basic settings for the data store

Module offset per pass

As the signals assigned to the reversing measuring location are added to the product file at each pass, they cannot retain their original signal ID. Otherwise there would be multiple signals with the same signal ID in the product file, which is not permitted.

Therefore we have this Module offset per pass setting, which calculates a new module number for each pass instead of the original module number. The offset is calculated by multiplying the value set here by the pass number.

The signal IDs of the signals in the first instance (Pass 1) would have a module number equal to the Module offset per pass setting. In the second instance (Pass 2), the signals would have a module number 2 x the Module offset per pass etc. up to n x Module offset per pass.

Using example of default value (10000):

Select the offset value to ensure that there is no clash with other module numbers in the system!

Reversing is done together with previous measuring location

This option should be enabled for successive reversing measuring locations starting from the second measuring location. Normally, ibaQDR expects the entry length to correspond to the exit length from the previous pass. However, if there are multiple reversing measuring locations in succession, the entry length should be compared with the exit length of the previous measuring location.

Note
	If the entry length does not match the associated preceding exit length, the previous data is “stretched” linearly and a message is posted in the event log.

A typical case for enabling this option is a combination of edger and roughing mill. These mills are usually located next to each other and the material passes through both mills in reversing operation. In this case you should enable this option for the measuring location of the roughing mill (which comes after the edger in terms of material flow).

Mirror head and tail

Enable this option for a measuring location if the production direction has reversed compared to the previous measuring location. For example, this is the case in beam rolling mills after lateral transportation of the material to the next roller table, where production runs in the opposite direction.

Skip missing passes

This option was created for coupled reversing measuring locations, e.g. as for combinations of edger and roughing mill. In reversing operation it may happen that the first part (edger) is not used every time. This means that the roughing mill can do more passes than the edger.

If you enable this option for the measuring location of the edger, the "missing" passes compared to the roughing mill will be taken into account.

The following figure shows the setting for the measuring location of the edger.

Example (theoretical)

The following figure shows the trend graphs for four measuring locations. The first two measuring locations are standard measuring locations, the third is a reversing measuring location and the fourth is a standard measuring location again.

We can see the length values (red and blue), the ID (green), the pass number (brown) and the digital “Last pass” signal (blue).

After each pass, the length signals are reset to zero on the entry and exit side. The tracking ID and pass number values can remain the same after a pass (as in the example) or be set to zero. As long as the tracking ID and pass number are not zero, time-based measured data is stored for the relevant pass.

Please note that the pass numbering depends on the setting in the QDR data store configuration, see also Basic settings for the data store.