The length-based data in the product file is mapped to the length at the measuring location where the file was generated. Stretching is carried out dynamically and iteratively using the configured entry and exit lengths for the measuring locations, i.e. starting with the measuring station where the file was generated, ibaQDR successively looks at each preceding measuring location, stretches the previous data accordingly if necessary and continues to the first measuring location in the line.

In the following real-world example of a pickling tandem line, the graphs show time-based signals for a product coil (ibaQDR DAT file) on the left-hand side and the length-based signals on the right-hand side. The first five graphs show signals from different measuring locations in the line (see reference arrows to line diagram), while the last graph shows the length signals from material tracking.

The progression of the length signals indicates that the line is run at different speeds and that a considerable elongation of the strip occurs in the rear tandem section. An entry product with a length of approx. 600 m is turned into a finished product 3000 m in length at the end, and all measured values are precisely mapped to the finished product length.

This length-based representation for the finished product is exactly what is required for a final quality assessment. It is important to determine which values were measured at which position on the finished product, for example to specify which strip sections have to be cut out due to tolerance violations during rework or to identify how many meters of the strip are outside the product specification and at which points.

The following graphs show a (theoretical) example of strip elongation.

The product coil is 12 m long. The first graph shows the length signals at the exit shear, plotted over the exit length (x axis).

The entry length (blue) and the length at the exit shear (red) are congruent. The red curve therefore covers the blue one. The green signal is any measurement signal acquired at the welder and shown stretched to the final length.

The second graph shows the situation at measuring location 2 (ML2). For the first 6 m there was no stretching at ML2. For the last 6 m, however, 100% stretching was identified. Therefore, at the entry to ML2 the coil was 9 m long and 12 m at the exit. The graph shows the entry length signal plotted against the exit length. The length signal is the same as at the shear as ibaQDR always uses the exit length to acquire the data at a measuring location.

The third graph shows the situation at measuring location ML1. The exit length here is 9 m. Creating an X/Y diagram of the shear length signal at ML2 and the entry length at ML2 gives the length at ML1. The length has a gradient of 1 for the first 6 m and then a gradient of 2 for the last 3 m. There is additional stretching at ML1. There is no stretching on the first 3 m, followed by stretching of 100 % on the last 6 m. You can see this from the ML1 entry length signal. The coil was 6 m long at the entry to ML1 and 9 m at the exit.

The fourth graph shows the situation at the welder. The exit length here is 6 m. The length signal at the shear is the result of an X/Y plot of the length signal at ML1 and the entry length at ML1. There was no stretching on the first 3 m, resulting in a gradient of 1. On the next 1.5 m there was 100% stretching at ML1, resulting in a gradient of 2. On the last 1.5 m there was 100% stretching at ML1 and 100% stretching at ML2, resulting in total stretching of 200% and a gradient of 4.

The green signal is a signal scanned at the welder. ibaQDR then uses the shear length signal at the welder to stretch the green signal to the length of the product coil. The result can be seen in the first graphic. ibaQDR expects the exit length from one measuring location to be equal to the entry length at the next measuring location. If it is not, ibaQDR stretches the signals uniformly. If the length difference is more than 0.5 %, an info field is written to the data file. The info field is called $QDR_MismatchBetweenExitAndEntryLengthAtMlx where x is the measuring location index. The value of the info field is the length difference in percent. If the difference is more than 10 %, an error is displayed in the event log.