Curvature development in ring rolling

Abstract

Loss of circularity when creating metal ring-shaped products by ring rolling is a significant industrial issue. This paper explores the previously tacit knowledge that plastic changes in curvature-required to maintain circularity-principally occur as material passes through the roll gap. Through a series of experiments and numerical simulations on half-ring workpieces, the 'free curvature change' is explored for the first time, finding that the ring can 'curl up'-the radius reducing by as much as-39% in a single pass-unless the inner roll is much smaller than the outer roll. An analytical model of free curvature change is proposed based on force equilibrium and compatibility. Under a range of 'normal' operating conditions this predicted free curvature change to within 7%. In (full) ring rolling the radius of curvature must continually increase. This paper proposes that regulation of curvature is achieved through bending moments at the roll entry and exit; largest when the tool size ratio is furthest from the optimum. This hypothesis is supported by Finite Element simulations of full ring rolling, finding entry and exit moments up to a quarter of the moment for a fully plastic hinge. This work could be of direct use to process designers in choosing tool sizes and guide roll force limits and suggests new ways to use guide rolls to better maintain circularity in challenging situations.

Management Control and Integration Technology of Intelligent Production Line for Multi-Variety and Complex Aerospace Ring Forgings: A Review

“…Figure 5 suppo the conclusion that the trapezoidal section blank was found to be about 1.4 mm mor curate than the rectangle in the finite element analysis, and the advanced nature o design could be certified convincingly. Considering that the size ratio and the thinning of ring forgings had a strong in ence on the free curvature change, Cleaver et al [49] established an analytical mod free curvature change based on force balance and coordination to reveal the influenc roll size on the variation of ring rolling curvature. At the same time, by repeatedly sea ing for mandrel size, the model could yield the ideal size change of ring forgings du the rolling process.…”

“…Figure 5. Section shape in three-roll cross-rolling process: (a) rectangular cross-section blank; (b) trapezoid cross-section blank with permission from [48], 2015, Elsevier.Considering that the size ratio and the thinning of ring forgings had a strong influence on the free curvature change, Cleaver et al[49] established an analytical model of free curvature change based on force balance and coordination to reveal the influence of roll size on the variation of ring rolling curvature. At the same time, by repeatedly searching for mandrel size, the model could yield the ideal size change of ring forgings during the rolling process.…”

Sheet metal forging process for thin-walled structures with crossed ribs: process design, simulation and a forming experiment

“…The samples were tested at four true strain rates: 0.01 /s, 0.1 /s, 0.2 /s and 0.4 /s. Cleaver and Allwood [13] have recently used a 0.05 mm thick PTEF sheet as compression testing lubrication between the specimen and the upper and lower die. Before each compression test, the PTEF sheets were all replaced.…”

Online measurement method for roundness of large aluminum alloy ring based on laser ranging principle

“…Inaccurate measurement can cause economic loss due to waste products without roundness and even damage the ring rolling equipment. [3][4][5] In summary, accurate measurement of the roundness of aluminum alloy rings during rolling is of great significance in terms of technology and economy.…”