Schuler supplying 800-kJ machine to forge crankshafts for large diesel engines, for trucks, locomotives, ships
Often, industrial technology proceeds at different paces depending on the regional market requirements; in North America and Europe, for example, there has been a notable rise in investments for new ring mill operations. Chinese forgers have been working to keep up with industrial demand on several fronts. The Chinese market for commercial vehicles does not draw as much attention as the comparable demand for automotive products, but the demand is great nevertheless. Recently, Schuler drew a contract to develop a new hammer mill for manufacturing large crankshafts for trucks, locomotives, and ships. Rated at 800 kilojoules, it will be one of the largest counterblow hammers that Schuler designs, and the largest it has yet supplied to a Chinese manufacturer.
A counterblow hammer mill uses two forging rams of similar mass that move synchronously toward each other, reaching optimal speed at the point of impact with the workpiece. The opposing thrusts of the rams offset, and the force of their impact is transferred to the workpiece rather than to the hammer’s foundation.
Hammer presses are among the earliest examples of industrial-scale forging technology, but the first counterblow hammer machine is credited to Bêché & Grohs, in 1932. Today, the Bêché product line is part of the Schuler group, which details that the high impact energy and tonnage of the hammer dies, moving in opposite directions, makes it possible to forge large-dimension parts with precision.
Counterblow hammers with hydraulic drives are particularly well suited to medium-tonnage production (there is no need to develop and install a complex compressed-air system), and Schuler’s DG series machines use pneumatic drives: This approach makes it possible to achieve very high levels of forging energy, and the rigid design of the upright stands, together with a reliable guide system, promotes high precision in forging parts.
Crankshafts, of course, are designed with careful attention to geometry and mass and weight distribution, so high precision in forging is essential. Also, the size of the parts to be produced is not an inconsiderable factor in the machine selection: the latest designs for diesel engines emphasize high fuel economy and low emission levels, which favors “long stroke” operation in order to reduce the RPMs. In turn, this underscores the need for large, heavy-duty crankshafts that tolerate high stress and bear high loads.
Schuler adds that its counterblow hammer design guarantees high availability and reduced maintenance requirements.
The finished Bêché DG80h machine will weigh approximately 650 metric tons, rising more than 7 meters (23 ft.) above the ground. Schuler noted it is the only company in the world building counterblow hammer machines of this size.
The developer will produce the various elements of the new machine at its workshops in Germany by mid 2017, then complete assembly at the Chinese site, for production to begin in early 2018.