An efficient approach for trimming simulation of 3D forged components--张启

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An efficient approach for trimming simulation of 3D forged components 毕业设计的外文翻译 立式数控钻铣床Article history:
Received 12 July 2010
Received in revised form
14 August 2011
Accepted 29 November 2011
Available online 8 December 2011
Keywords:
Trimming operation
Precision forging
Aerofoil blade
Finite element
Trimming operation as an important stage of many sheet and bulk metal processes is geometrically and
physically complex and computationally challenging. This is especially true for metal forming processes
where net-shape specification is critical. In this paper， we present an efficient approach for fast
trimming simulation of 3D forged components so that the effect of such trimming operations on post-
forming material spingback， thermal distortion and final dimensional and shape accuracy of formed
parts can be quantified. This approach comprises steps including definition of trim line， elimination of
discarded elements， adjustment of nodal positions close to the trim line and mapping of the state
variables from the original mesh to the new mesh. To evaluate the effect of residual stresses in
trimming operation， a new algorithm involving a scaling interpolation and coordinate transformation
procedure is proposed so that limited 2D trimming simulations can be used to quantify and to map
trimming induced residual stresses onto the whole 3D model for further process simulation. This
developed trimming simulation approach was verified using an industry case study in hot forging of
a 3D aerofoil blade by three post-forging cooling simulation cases including an untrimmed blade，
a trimmed blade and a trimmed blade with the inclusion of trimming induced residual stresses.
The simulation results were compared with actual measurement data of the forged aerofoil blade with
excellent results obtained. The results show that the trimming operation has a significant effect on
post-forging springback and thermal distortion but much less so on thickness of the aerofoil sections of
the forged blade. The results also demonstrate that the proposed trimming simulation approach is
computationally efficient and robust for other bulk and sheet metal forming processes of complex
shapes.
& 2011 Elsevier Ltd. All rights reserved.
1. Introduction
Precision forging is a competitive manufacturing method for
structural components such as crank shafts and gears used in
automobile industry and aerofoil blades for aeroengine applica-
ions as it produces high quality forged parts in terms of material
microstructure， mechanical properties as well as dimensional and
shape accuracy with reduced material waste and overall cost.
However， precision forging of such components is normally
achieved through a multistage route instead of a single operation.
For example， hot forging of high temperature alloy into aerofoil
blades normally involves extrusion， forging and trimming before
cooling of the trimmed blade to room temperature as shown in
Fig. 1. Steffens and Wilhelm [26] reviewed the improvement of
orging quality and accuracy through various means of technolo-
gical advances and in particular computer based process simula-
ions. In these methods， Finite Element (FE) simulation is most
widely used to evaluate material flow， stress/strain and tempera-
ture distributions and to validate process design. In current
practice， the main steps of forging operations including preform-
ing， forging， unloading and cooling can be effectively simulated
either using commercial software or in house simulation packages.
However， in these simulation procedures one important operation
required in actual forging process， i.e. trimming of flash of the
forged parts carried out immediately after the removal from
forging dies and before cooling to room temperature is not easily
dealt with. This is because of two main important reasons. Firstly
the trimming process is geometrically and physically complex.
Although it is now possible to simulate a 2D or 3D trimming
process of a simple part using commercial FE software function-
alities， it is computationally prohibitive to simulate a large scale
trimming process of a complex component such as the aerofoil
blade. Secondly， even if large scale trimming simulation is possi-
ble， it is mostly treated as a standalone process. The effect due to
the trimming operation on the geometry， stress， strain and
temperature distributions is often neglected. The lack of ability
to simulate trimming operation in the whole multistage forming n
Corresponding author. Tel.: þ44 115 8467391; fax: þ44 115 9531800.