Measuring systems for rod and bar

PROFILE MEASUREMENT OF WIRE ROD IN A MULTIPLE STRAND MILL

THE REQUIREMENTS

Increasingly, the customers of ArcelorMittal Hochfeld GmbH require products with tight dimensional accuracy. To control the H/V rolling process efficiently and to comply with quality assurance requirements, key dimensions of the rods such as height, width, shoulder sizes and out-of-round must be available in real-time.

The existing oscillating single-axis gauges could neither display the complete profi le to determine width and height nor over- or underfill. Therefore samples still had to be cut and measured manually. Furthermore, the samples were not representative for the entire coils. Hence a new profile measurement system became necessary.

The new measurement system should determine diameter and profile along the entire length of the billet to allow optimal crop cuts at head and tail of the billets. The trend towards ever smaller production lots resulting in frequent changes of size and steel grades requires to assess and display the rod diameter and profile in real-time, thus allowing to quickly adjust the mill to roll within the required tolerances. To monitor all 3 strands in parallel and to display profile data independently on 6 terminals, a networked system was needed.

As the rod can break out at any gap of the guides a system with smallest footprint was needed. Therefore only a compact system could be considered.

 

The solution

ArcelorMittal Hochfeld GmbH decided to install LAP RDMS systems, because they fulfilled all requirements. In each of the three strands, RDMS gauge heads are located behind the wire rod blocks to obtain results with minimum time lag and to ensure gap-free high precision monitoring of sizes along the entire length of each rod.

LARGE BENEFITS FOR THE MILL

No limit violation can go unnoticed! No other systems provide similar dense readings of the entire rod surface. Deviations and trends are detected immediately. Thus, the operators can take preventive correcting actions even before tolerance limits are violated.

 

HIGHER DIMENSIONAL ACCURACY

  • Since the system operates and displays in real time, a glance at the monitors provides the operators with detailed information about the rolling train status. 
  • Push/pull conditions, roll gap settings and even asymmetric fill of the finishing pass are monitored and can be optimized. Corrective action can be taken immediately to ensure continued dimensional accuracy of the rolled stock. 
  • Repeating dimensional surface defects which originate from roll breaks can be detected immediately, calling for replacement of the finishing passes.

HIGHER YIELD AND UTILIZATION

  • The ramp-up after size or grade changes could be shortened dramatically. Normally, final mill set-up is achieved during run time of a starter bar or the first billet, improving mill utilization. 
  • By optimizing the crop lengths at head and tail the mill yield could be increased, too. 
  • The certitude to quickly roll within tolerances after changes of steel grade or product size has increased considerably


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