Wall thickness monitoring while stretch-reducing tubes

A controller (2) for controlling a stretch-reducing mill (1) for the rolling of tubes (R), the stretch-reducing mill (1) having

• several roll stands (10) arranged behind one another in a conveying direction (F) of the tubes (R), and
• at least one outlet-side wall thickness measuring device (20) for measuring outlet-side wall thicknesses (sr) of tubes (R) exiting from a last of the several roll stands (10),
• wherein the controller (2) is configured
• to receive measurement data relating to one or more outlet-side wall thicknesses (sr) of a tube (R) exiting from the last of the several roll stands (10) from the wall thickness measuring device (20),
• to determine one or more inlet-side wall thicknesses (sl_t) of the tube (R) before entering a first of the several roll stands (10) from the received measurement data, and
• to control one or more of the several roll stands (10) taking into account the determined inlet-side wall thicknesses (sl_t).