Ring Sizers

Ring sizers (or expanders) serve an important function in the production of seamless rolled rings. Their primary purpose is to accurately size a ring ID to the customers specifications. Many factors beyond the ring rolling process can affect the roundness of a rolled ring. Temperature uniformity and pre-form concentricity are two. This can lead to rings which may be out-of-round. For rings in the 750mm-1800mm range (30" to 70"), 3mm (1/8") out-of-roundness is common. Rings are frequently rolled 6-10mm (1/4"-3/8") undersize and then immediately taken to a ring sizer while hot, for a final "stretching", which produces a round ring with an accurate and repeatable inside diameter.

Another common use for sizers is for metallurgical purposes such as "cold working", or performing grain refinement by deforming material at reduced temperatures.

Although sizing is not a mandatory process in producing seamless ring, sizers pay for themselves by minimizing the "forging envelope", and therefore raw material due to the ability to maintain superior dimensional accuracy over ring rolling alone.

In order to select a sizer tonnage, the customer must first have at hand information on the "hoop force" desired as well as the diameter range. The hoop force is the maximum stretching force generated at any point in the ring cross-section. In order to determine the force necessary to deform a given product, the ring dimensional cross section must be known, as well as the yield stress while at forging temperature. Burns engineers are able to provide you with recommended machine specifications based upon your forging requirements.

Push up stepped sizers		Pull-down sizers

AVI Video file of stepped sizer in motion.		AVI File of pull-down sizer in motion
Push up style ring sizers, sometimes called stepped sizers, are very practical when sizing a large variety of small and relatively short rings. The key advantage to these machines is that they do not require spacer tool changes. A typical sizer can have an ID range from 150-400mm (6" to 16") and a height limit of about 150mm (6").		Pull down sizers are most common in the ring forging industry. They are cost effective, and very powerful. The primary down-side to these sizers is the time required to set up spacer tooling. Spacer ring segments are necessary to extend the stock tooling to the desired diameter range. It can require 5 to 30 minutes of preparation before a given ring can be sized.

Burns Machinery Inc