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A heavyweight journeyFrom steel blank to slewing bearing
It is a long journey from a solid piece of steel to a fully functional slewing bearing. The production process begins with a cylindrical steel billet and ultimately ends at thyssenkrupp rothe erde, where it becomes the ready-to-use centerpiece of a wide range of applications.
The first steps: From the warehouse to the saw
The journey of the gigantic steel rings begins in the ring rolling mills at thyssenkrupp rothe erde. But at the start, there is still no sign of their future diameter. At this stage, the cylindrical steel strands have a diameter of only 180 mm to 1,500 mm and weigh an average of about 21 metric tons. They are therefore transported to the sawing facility using a high-voltage electromagnet.
Each of these steel strands weighs an average of 21 metric tons and serves as the starting point for the production of high-performance, high-quality large-diameter rolling bearings that are used all over the world.
From cylinder to “glowing donut”
In the cutting shop, a high-performance saw slices through the steel billet. The size of the separated steel cylinder depends on the final geometry required for the slewing bearing and can therefore vary from one order to another. To shape the steel cylinder into a ring after sawing, it first has to be heated. In special furnaces, the steel cylinder is heated to temperatures of up to 1,200 degrees Celsius.
A red-hot steel cylinder on its way from the furnace to the press, where it will be shaped into a ring.
Using a pressing force of 6,000 metric tons, the red-hot steel is first formed into a disc and then into a seamless rolled ring.
Heated steel blank in an industrial furnace in preparation for the production of a slewing bearing. A glowing steel cylinder on its way from the furnace to the press, where it will be shaped into a ring.
Rolling and heat treatment
The initially donut-shaped steel ring is finished in a CNC-controlled and monitored rolling process. This is followed by a precisely defined heat treatment, during which the ring acquires its required mechanical properties. These are then verified using a range of destructive and non-destructive testing methods.
The steel ring takes on its final shape during the CNC-controlled rolling process. Subsequently, specific heat treatments ensure that it achieves the desired mechanical properties.
The finished large-diameter roller bearing ring after machining: Precision manufacturing and comprehensive quality inspections ensure that it meets the highest standards.
The ring is machined and the slewing bearing assembled
At thyssenkrupp rothe erde, the rings are given their final contours through various machining steps, including raceways, boreholes and, where required, gearing. These features enable functions such as rotational movement and connection to the surrounding structure. To increase the service life and wear resistance of the bearings, the raceways and wear surfaces are hardened using our induction hardening process.
Depending on the design and required tolerances, the slewing bearing is then finished either by hard turning or grinding. A combination of both processes is also possible. Once final machining is complete, the rings are assembled.
The decisive moment: Everything has to fit
There is no turning back now: this is the moment of truth. Whether all the production steps have worked together properly becomes clear when the outer and inner ring - or upper and lower ring - are brought together and function as a slewing bearing, enabling smooth rotational movement without difficulty. During final inspection, both internal and external specialists examine the manufacture of the rothe erde® slewing bearing. Final dimensional checks are carried out, and the forces required for the bearing’s rotational movement are verified.
Major industrial construction projects depend on the successful manufacture of slewing bearings. Defects in production would not only cause delays, but also significant costs - not least because entire projects could come to a standstill if, for example, construction of a wind turbine cannot continue because delivery of a slewing bearing is delayed. That is why our experts at thyssenkrupp rothe erde rely on high-quality, precise work based on more than a century of experience and the latest technological know-how.