Using this model, it is apparent that the key to minimizing distortion is to select a fabrication process that (1) uses input material with little or no residual stress and (2) will permit a subsequent processing path that introduces as little residual stress as possible. To form a plate into a cylinder, in most cases, it will require stretching the metal beyond its yield point to both hold the cylindrical shape and allow for the subsequent spring-back. If it is assumed that the starting plate is essentially free of residual stress due to processing at elevated temperatures (a large assumption, indeed), the equilibrium state of the plate is subsequently changed during rolling through the introduction of tensile and compressive stresses that shift the equilibrium state to that of a cylindrical shape (requiring a weld to hold it in place because of the tendency to spring back, in particular with materials having a high yield strength).
If you are looking for more details, kindly visit RUNCHI.
Understanding the proportional relationship between stress and strain (elastic modulus), it can be intuitively understood that the stretching will spring back to a new state that now has residual stress present. In addition, the introduction of the longitudinal weldment to complete the cylindrical shape further disrupts the system through the introduction of thermal energy. The severity of the residual stress will increase with increases in either, or all, of the yield strength of the base metal, circumference of the tube and plate thickness. Once the desired shape is achieved, it will remain in that shape as long as no subsequent processing or service conditions that alters the stress state is performed (machining or welding, for example). When the part does distort, additional mechanical work is required to revive the desired shape, resulting in an often "circular" manufacturing path. These costs are often not considered when selecting a rolled and welded cylinder.
Unlike other types of ring forming, this forging process creates a seamless ring with great integral strength, capable of resisting high degrees of internal or external pressure. This is why wheel hubs, bearing housings, pressure vessels, gears, jet engine bearings, engine turbines and wind turbines - all applications which apply significant force - are usually made from seamless forged rings.
Seamless rolled rings are also utilized in nuclear reactors, off-road equipment, couplings, rotor spacers, sealed discs and cases, flanges, valve bodies and many other high stress applications.
Contact us to discuss your requirements of Rolled Ring Forging. Our experienced sales team can help you identify the options that best suit your needs.
A seamless rolled ring begins as a solid, circular block of metal that is heated to forging temperatures and then punched through the center to form a "donut" shape. This preform is then placed on a rolling rig with a roller touching the inside of the donut and a roller touching the outside of the donut. The two rollers begin to rotate in opposite directions, turning the ring, and at the same time the rollers slowly squeeze inwards, thinning the ring wall and causing the diameter of the ring to increase.
Some ring-rolling machines also have a roller that presses down on top of the ring as it turns, governing the height of the ring wall. The process continues until the ring has been thinned, flattened or otherwise shaped to its desired dimensions, at which point it may receive secondary processing such as size fine-tuning or heat treatment. Rings can be shaped at high forging temperatures for faster forging or, for rings that require the highest pressure resistance, such as aluminum car wheels, the rolling can be done at lower temperatures over a longer period.
Lower forging temperatures and longer forging times result in greater tensile strength. The ring-rolling process can be modified in any number of ways to produce a wide range of precise contours both on the inner dimension and outer dimension. Seamless rolled rings are unequaled in tangential strength, ductility, and adaptability.
If you are looking for more details, kindly visit Forged Step Shaft.