SMS group is testing new concepts for the table-type ring rolling mill KFRWt neo in various projects.
In recent years, SMS group was able to exceed limits of previously rolled ring geometries again and again. Most recently, a ring rolling machine RAW 2500/1250-16000/3000 was installed at a Chinese customer capable of successfully rolling ring diameters of 16 meters with ring weights of up to 130 tons for the first time.
In addition to ring rolling machines for such extreme ring dimensions, SMS group builds also automated mechanical ring rolling machines which make it possible that rings are rolled with cycle times of a few seconds. For these automated machines the ring dimensions are up to an external diameter from 100 to 500 millimeters.
Besides a radial multi-mandrel ring rolling machine of the MERW type, the radial multimandrel ring rolling machine, type KFRWt neo, should be mentioned as another example. The KFRWt of old design is a table-type ring rolling machine, the design principle of which has been known since the beginning of the 20th century. KFRWt stands for the acronym semi-automated Kreuser spring-ring rolling mill.
The original developer, the firm Adolf Kreuser GmbH, Hamm, is the predecessor who has been absorbed by the German machine-tool factory Wagner & Co. from Dortmund. Later, Wagner & Co. merged with J. Banning AG from Hamm to form the WOB Ringwalztechnik GmbH and was integrated as Wagner Banning Product Area into SMS Eumuco in 1997. SMS Eumuco was incorporated into SMS Meer in 2007 and was finally merged with SMS Siemag GmbH in 2015 to form the SMS group.
While the focus of KFRWt was initially on rolling spring rings for railroad car buffers the range of application for the automated ring rolling machines was expanded rapidly by manufacturing also rings for the bearing and automotive industries.
The KFRWt features four rolling stations arranged on a turntable. Each station is equipped with a centering arm, a mandrel roll and roll table. The turntable surrounds a driven main roll. Its axis and the axis of the turntable are eccentrically arranged to each other. Through the rotary movement of the table around the main roll the rolling gap between main roll and the respective mandrel roll is continuously downsized. As a result, the wall thickness of the ring blank which was previously loaded onto a rolling station is continuously radially reduced. Due to the reduction of wall thickness the ring diameter is increasing. As soon as the adjust rolling gap has been reached the rolling process is completed. The rolled ring can be unloaded from the rolling station and the station can be reloaded with a blank.
For the original KFRWt, the minimal wall thickness and the position of the centering arms during the rolling process are adjusted via mechanical setting elements which had to be partially adjusted for all rolling stations in a time-consuming procedure when product change takes place. To reduce the non-productive times SMS group has revised the concept of the KFRWt and automated the product-dependent adjustments by means of servo technology. Depending on the ring complexity, up to 720 rings can be rolled per hour, whereby investment costs pay off quickly. SMS group succeeded in placing already four reengineered KFRWt neo units in the market.
In addition to the industrial environment, the table-type ring rolling mill KFRWt neo can also be employed for research purposes. SMS group is successfully cooperating with different research institutions.
Among others, the Ring/Wheel Rolling Division investigated together with the Technical University Cottbus (BTU Cottbus), Germany, the combination of additive manufacturing (3D printing) and forming technology. By means of WAAM (Wire Arc Additive Manufacturing) preforms from 1.5125 could be manufactured additively for the first time and then rolled on a KFRWt neo. During initial trials, inner preform diameter and height were remachined. The examinations showed in general the formability from accordingly manufactured preforms.
In addition, the possibilities of additively manufacturing preforms from special alloys will be investigated. The goal is to create options for manufacturing profiled preforms which until now cannot or which can only be manufactured in an expensive procedure with conventional process routes. Furthermore, examinations should also be performed to find out whether functional layers are printed onto conventionally manufactured forged preforms by means of additive manufacturing. Example applications can be found among others in the bearing industry where the bearing surfaces should reveal other mechanical wear properties compared to the base material of the bearing.