MEASURING SYSTEMS FOR ROD AND BAR

PRECISE PROFILE MEASUREMENT OF THREE-LOBED BARS

THE REQUIREMENTS

Swiss Steel AG produce very small lot sizes and therefore have to change sizes frequently. During start-up this requires dense control of diameter and profile along the billet to roll within the given tolerances as quickly as possible after size or grade changes. After installation of a new 3-roll sizing block supplied by Friedrich Kocks GmbH, a suitable measurement system was needed for installation about 8 m behind the new rolling stand.

 

The solution

A first four-axes RDMS system behind the last stand of the bar mill section was commissioned at Swiss Steel AG (formerly von Moos Stahl AG) in July 1997. LAP had guaranteed that the expected cost savings would become evident within six months.

Indeed, the expected return of investment could be realized. The calculation of profitability was based on shortening the start-up phases. In August of 2000 this system was moved to the Stelmor line, and an additional RDMS system with six axes was put in operation behind the H/V finishing train instead.

From August 2002 it was used for commissioning of the new Kocks RSB block. Having six axes and using LAP’s patented “True-Shape” 3-point measurement technology, it can detect and measure all relevant shape defects, and namely three-lobed shapes precisely.

The advantages

The system checks every single bar over its entire length for meeting the diameter and roundness specifications. As deviations are signalled immediately, the operators can quickly take corrective action.

 

HIGHER DIMENSIONAL ACCURACY

  • The undelayed real-time display of profile and dimensions provides complete information on the rolling process at a glance immediately when the bar enters the gauge and over its entire length – especially from head and tail.
  • Using the feedback from the RDMS measurement push/pull conditions between rolling stands as well as the rolling stand adjustments of the entire rolling train can be optimised. On imminent deviations corrective action can be taken immediately to ensure that the product complies with the specifications.

HIGHER THROUGHPUT, HIGHER YIELD, HIGHER UTILIZATION

  • After size changes the rolling train is ramped-up to the new dimensions much faster than before. In general adjustment are carried out already while the fi rst billet is still being rolled.
  • The operators don’t need to wait for the results of manually cut samples. Depending on the cooling method, this could take up to eight minutes in the past. Now production runs without delays from the first billet on.
  • The dense measurements along the bars provide precise determination of off-size lengths at head and tail, allowing optimal crop cutting and increased shipment of good material.
  • The certitude to quickly roll within tolerances after changes of steel grade or product size has increased considerably.

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