New measuring method registers the position of glowing steel rings

New measuring method registers the position of glowing steel rings

By Mirko Gröper, David Bailly and Gerhard Hirt

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Ring rolling creates parts that are indispensable in many industries. In order to be able to map an even wider product range, researchers from Aachen have developed a new measurement method.

Rolling of a red-hot steel ring on a Banning H100 / V80 radial-axial ring rolling mill at the Department of Metal Forming in Aachen. Now the position of such items can be registered accurately. Find out how it works here.

(Image: Ahrens + Steinbach Projects)

Ring rolling is a well-established and economically solid forming process for the production of large seamless rings, which are used, among other things, as safety-relevant components in the energy, automotive and aerospace sectors. [1]. Typical applications are roller bearings or connecting flanges for wind turbines [2]. Also components for aircraft turbines [3] belongs to. In addition to the long service life and the good mechanical properties of ring-rolled products, the process is characterized by a very high material efficiency, especially when non-rectangular, almost-mesh-shaped cross-sections are made with it. [4].

Ring-rolling targets are not trivial

In recent years, opportunities have been developed to make the process more flexible by expanding the product range of conventional radial-axial ring rolling mills, for example in the production of profiled steel rings. Among other things, approaches were chosen that complement the conventional system technology with measurement and control concepts. However, due to the complexity of the ring rolling process, this process places high demands on operational measurement technology. In hot solid forming, the harsh conditions such as water vapor, dust, vibration, external light sources and the high degree of ring coverage of the tools strain the metrological systems. In addition, the high temperatures above 1,000 ° C that normally prevail during hot forging can significantly degrade the accuracy of the measurement technology and even damage it in the long run.

Location of the spur despite harsh conditions

As part of an ongoing DFG project, the Department of Metal Forming (IBF) requires ring rolling of eccentric rings that are close to mesh shape with a peripherally variable wall thickness. To achieve this, the ring position or the actual wall thickness in the roller slots must be accurately tracked because the opening and closing of the radial roller slot (dynamic adjustment of the mandrel roller) must be controlled on the basis of these variables. Therefore, a new idea was pursued which, despite the harsh conditions, can trace the rotation of the ring and on the basis of it its position.

The choice fell on measuring the peripheral speeds of the centering rollers because it can be measured independently of the forming zones. This avoids any falsification of the measurement. Basically, with this knowledge, the peripheral velocities of the ring can be determined. By incrementally adding the individual time intervals, the distance traveled around the circumference can then be calculated. The distance can be adjusted in relation to the predominant wall thickness of the ring. Finally, one can determine the position of the ring in the ring rolling mill. In addition, with the expansion of the measurement technology at the ring rolling mill, additional support points can be created, with which further data on the condition of the ring during the rolling process can be collected. This data can be used to perform an extended comparison of the actual ring position to simulate the process. With this knowledge, new rolling strategies can then be developed in a simulative way.

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