20th International Forgemasters Meeting - IFM 2017

When rolling rings with high-precision and a high speed, it is crucial to accurately determine the dimensions of the ring. The conventional method for measuring this was to push a measuring device in direct contact with the ring. Recently ring measurement is shifting from mechanical measuring with a measuring cylinder towards non-contact measurement methods like laser sensors. However, there are several downsides to laser sensor measurement; e.g. the dependency of the measurement accuracy on the distance between the laser and the target, but also the need to adjust the mechanical structure of the machine for the installation of the laser sensor. Therefore, we have started the development of a new non-contact measuring system using an imaging sensor in 2013. The purpose of this system was to be able to perform stable and precise measuring. We have installed it at an actual production facility in November 2015. The imaging sensor consists of a high-quality camera, attached with ball screw to a mounting block which can be moved horizontally through an AC servo motor. In other words, the imaging sensor itself is able to follow the ring as it grows. The captured images are projected on a monitor, which already displays a predetermined reference line. The position of the camera is controlled based on the Manipulated Variable (MV), which is the difference between the edge (position on the ring rolling surface) of the ring and the imaging sensor reference line. The ring outer diameter is determined by the sum of "the position of the camera" and "difference between the reference line and the ring surface". The imaging sensor's measurement accuracy is approximately ±1mm. We have confirmed the following benefits of this system: There is no mechanical wear when measuring with the imaging sensor. It is more cost-effective than lasers sensors since it requires only 1 imaging sensor. It can be applied to other equipment as well, so it is not limited to ring rolling mills.