03/09/2010

Finished railway wheel in one step: Schuler installs Dishing Press in Spain

Railway infrastructures are growing around the world – and at quite a pace in some regions. Many of Europe’s industrialized nations are also currently investing heavily in their rail networks. Obviously, this is also helping drive the economic development of the railway industry. There is strong growth, for example, in the number of wheel sets needed to cope with the rise in rail transport – particularly as railway wheels are subject to high wear. The Spanish railway vehicle manufacturer Contrucciones Y Auxiliar de Ferrocarriles (CAF) was quick to react to this trend and has replaced its wheel manufacturing equipment with new and more powerful machines. At CAF’s facility in Beasain, Spain, production was recently launched on a 5,000-ton dishing press from Schuler SMG for the piercing and dishing of railway wheels. The press closes the last gap in a now fully automated and highly modern production process.

High loads, tight bends, strong acceleration and emergency braking – railway wheels have to cope with extreme levels of stress. Dr. Walter Osen, Head of the Forging Business Unit at Schuler SMG in Waghaeusel, explains: “The wheels have to withstand permanently high loads while transmitting tremendous forces onto the rails. Uneven wear and tear, caused primarily by braking, means that the wheels must be regularly reworked to become perfectly round again. In addition to the usual wear from operation, this reworking significantly shortens the wheel’s service life.

Gap closed in production process

A new 10,000-ton press from Schuler SMG for pre-forming railway wheels has already been in operation at CAF for almost a year. In a two-stage operation, it forges a pre-form from a cylindrical block which is then rolled out on a wheel rolling mill. “Until recently, the subsequent production step – the piercing and dishing of the pre-form – was done on an older machine. This gap in the process has now been closed. We have replaced the old 2,500-ton press with a new 5,000-ton-strong press from Schuler SMG,” says Dr. Walter Osen. The addition of the new press means that the entire forging line can now be run fully automatically. The increased press force also allows lower tolerances for the forged part. As a result, the customer also profits from considerable weight savings.

Dishing and piercing in a single production step

The capability of the line becomes apparent from a first look at the production process. Several stages of railway wheel production can now be completed with a single stroke of the slide. The press simultaneously flanges the rolled wheel, calibrates it to size and punches the hub. “In this context, dishing means forming the inner wheel disk from a symmetrical to an asymmetrical shape. At the same time, the wheel’s hub is axially offset. On the old press, this process and the required piercing still had to be done in two stages. With the new press, both are completed in a fully automatic process,” explains Dr. Walter Osen. The machine boasts an integrated piercing cylinder for the piercing process. Its punch pierces through the wheels with a force of 1,000 metric tons. Once the dishing and piercing operations are completed, a hydraulic ejector in the bed pushes the wheel out of the die and lifts it to a precisely programmable transfer height for the unloading robot.

“The solution provides CAF with a state-of-the-art automated line,” explains Dr. Walter Osen. This also includes a die changing system: if a change is due, the die is closed in the press and the hydraulic clamps for the dies and punch are automatically released. A die change cart accepts the die and takes it to a preparation table at the side. The loading and clamping of the new die then follows the same procedure, but in reverse. An easy-to-operate press control system helps the machine operator program and control the line.

Different wheel formats – same high quality

The Schuler press installed for CAF boasts a large number of dies. After all, the line is used to manufacture a wide range of different wheel variants – for trolley cars, local transport trains, freight and high-speed trains. As a consequence, the diameter of the wheels forged on the dishing press range from approx. 600 millimeters to 1,400 millimeters. “Whichever wheel variant is produced – CAF always benefits from the performance of its new manufacturing solution,” stresses Dr. Walter Osen. This is not only due to the production step which is saved. The much higher press force of the new Schuler line and optimized die concept developed together with Schuler lead to an overall increase in part quality. More efficient production on the one hand, higher part quality on the other: “CAF is now ideally prepared for the expected production growth in railway wheels and for the future ahead,” states Dr. Walter Osen.