Explanation of the mushroom effect in the rotary forging of a cylinder

Liu, Gang; Yuan, Shijian; Wang, Z.R.; Decheng, Zhou

doi:10.1016/j.jmatprotec.2004.04.035

Cited by 74 publications

(30 citation statements)

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“…Next, Canta et al [8] described the major aspects of energy distribution in a rotary forging. Liu et al [12] discussed e.g. the mushroom effect and Decheng et al [13] explained the other important limitations of the process.…”

Section: Introductionmentioning

confidence: 99%

Studies on Stress and Strain State in Cold Orbital Forging a AlMgSi Alloy Flange Pin

Samołyk¹

2013

Archives of Metallurgy and Materials

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The orbital forging is one of the metal forming processes which enables the manufacture of products through worm or cold working. A characteristic feature of this technological process is the use of a special wobbling motion of one of the tools in order to reduce the required forming force. This is particularly advantageous during the formation of products in the shape of a disc or a flange pin. Unfortunately, typical constraints of cold orbital forging are: uncontrolled buckling, loss of shape stability ("mushroom effect") and cracks. They depend on the technological parameters of the process and their cause can be explained on the basis of e.g. workpiece stress state analysis, which is a difficult task due to the complexity of orbital forging process. The article discusses the issues of stress and strain in cold orbital forged parts of the flange pin type, made of AlMgSi aluminum alloy. The results of the presented FEM simulation, verified experimentally, explain the influence of the theoretical aspects of this process on its implementation conditions. It is assumed that orbital forging is performed on the PXW-100A press and the numerical model takes into account all possible variants of the process. Debate boils down to discussing the stress and strain state (e.g. analyzing the stress and strain rate fields) occurring in the workpiece in the context of chosen technological parameters and constrains of orbital forging process.Keywords: orbital forging, stress and strain state, aluminium alloy, FEM, experimentPrasowanie obwiedniowe jest jedną z technologii obróbki plastycznej, która umożliwia wytwarzanie wyrobów poprzez ich kształtowanie na zimno lub ciepło. Wyroby prasowane obwiedniowo charakteryzują się stosunkowo dużą jakością powierzchni oraz małą tolerancją wymiarową. Charakterystyczną cechą tego procesu technologicznego jest zastosowanie specjalnego ruchu wahającego jednego z narzędzi w celu obniżenia wymaganej siły kształtowania. Szczególnie korzystne jest to podczas kształtowania wyrobów typu tarcza lub sworzeń z kołnierzem. Typowymi ograniczeniami prasowania obwiedniowego są niekontrolowane wyboczenie, utrata stateczności kształtu oraz pęknięcia. Zależą one od parametrów technologicznych procesu, a ich przyczynę można wyjaśnić na podstawie np. analizy stanu naprężenia panującego w wyprasce. Z uwagi na złożony charakter prasowania obwiedniowego jest to zadanie trudne. W artykule omówiono zagadnienia stanu naprężenia i odkształcenia w prasowaniu obwiedniowym części typu sworzeń z kołnierzem, która jest wykonana ze stopu aluminium AlMgSi. Przedstawione wyniki symulacji, zweryfikowanej doświadczalnie, wyjaśniają znaczenie aspektów teoretycznych tego procesu na jego warunki realizacji. Zakłada się, że prasowanie obwiedniowe jest realizowane na prasie PXW-100A, a model numeryczny uwzględnia wszystkie możliwe warianty realizacji procesu na tej maszynie. Dyskusja sprowadza się do omówienie stanu naprężenia i odkształcenia (analizując prędkość odkształcenia) panującego w wyprasce w kontekście wybranych parametr...

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Section: Introductionmentioning

confidence: 99%

Studies on Stress and Strain State in Cold Orbital Forging a AlMgSi Alloy Flange Pin

Samołyk¹

2013

Archives of Metallurgy and Materials

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“…The explanation to this behavior is that the forming force is large enough in RHF to produce uniform shear strain throughout the specimen as stated in previous works [3,12]. Liu et al [14] have used a 3D rigid-plastic finite element method to simulate RPF and to reveal the deformation mechanism of the mushroom shape workpiece. They concluded that the mushroom shape is due to nonuniform deforming degrees along the tangential direction at various heights of the workpiece.…”

Section: Effect Of Rotational Speed On the Mushroom Effectmentioning

confidence: 92%

Effect of rotational speed in rotary hammer forging process

Hamdy

2015

MATEC Web of Conferences

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Abstract.Rotary press forging (RPF) has been used in the last century, but it produces many defects in the forgings. The author has invented the rotary hammer forging (RHF) process to reduce such defects. RHF is a multi-axes compression process where the material is partially and incrementally deformed by the action of several repeated hammering blows, while the produced deformation region is swept through the whole area of the workpiece. The aim of the present work is to study the effects of rotational speed on the forgings produced by RPF and RHF to compare between the two processes. It has been found that as the rotational speed increases the mushroom effect is constant in RHF while it is greater and increases in RPF. As the rotational speed increases, the twist angle increases in both RHF and RPF, but it is bigger in RPF. These results demonstrate the benefits of using RHF instead of RPF.

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“…For orbital forming, the three-dimensional material flow and rotating contact area resulting in a greater outer diameter of the workpiece on the contact side between workpiece and rotating die, leading to the so-called ''mushroom-effect'' [32]. However, this effect is primarily of interest when applying orbital forming on bulk metal as these parts normally have a higher initial thickness.…”

Section: Process Adapted Semi-finished Parts For Directing the Materimentioning

confidence: 99%

Innovative approaches for controlling the material flow in sheet-bulk metal forming processes

et al. 2016

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-Using sheet-bulk metal forming processes the application of bulk forming operations on sheet metals enables the manufacturing of functional components with local wall thickness variations. As these processes come along with a two-and three-dimensional material flow, the control of the material flow is crucial for ensuring a proper filling of functional elements and thus ensuring the components quality. Controlling the material flow can be achieved by different solutions: the local adaption of tribological conditions and the application of process adapted semi-finished parts. In this paper, both solutions as well as their general qualification in two sheet-bulk metal forming processes are presented.

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Explanation of the mushroom effect in the rotary forging of a cylinder

Cited by 74 publications

References 1 publication

Studies on Stress and Strain State in Cold Orbital Forging a AlMgSi Alloy Flange Pin

Studies on Stress and Strain State in Cold Orbital Forging a AlMgSi Alloy Flange Pin

Effect of rotational speed in rotary hammer forging process

Innovative approaches for controlling the material flow in sheet-bulk metal forming processes

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