Abstract: An uncertain approach has been evaluated to analyze the finite element analysis
responses for the springback evaluation on a stamped part. In the Metal Forming and Springback
simulations a deterministic approach does not take in account uncertain physical variations related
to material characteristics, friction conditions, tools active surfaces status, etc. Then, if one of the
purposes of the process design it is its reliability, a CAE study in aleatory conditions is the only way
to evaluate the process robustness. A study case has been defined and the explicit simulation was
performed for the forming stage while, the implicit simulation was performed for the springback
phase. Subsequently, a stochastic problem was solved to found the aleatory influence of process
parameters such as: anisotropy coefficient, Young modulus and friction between blank and tools to
evaluate their effect on the component springback. The evaluation of finite element models in
uncertain conditions can be considered like a CAE usage in order to obtain a “Robust Design” for
the examinated problem.
Abstract: Medical examinations and treatments using endoscopes are becoming increasing common
due to their minimally invasive nature. Many types of medical devices for endoscopic therapy are
available, and of these, forceps are most frequently used. Forceps prices are on the whole high, and
one of the reasons for this can be attributed to the manufacturing method. Currently forceps parts are
made by cutting or metal removal process. By replacing these methods with die forming, stable supply
at low costs should be possible. This paper describes a study proposing and developing a forceps
manufacturing method by die forming, and describes the successful results. It also reports the
evaluation carried out on functions of the prototyped forceps and the proposed method of changing
the shape of products for which die forming is not suitable.
Abstract: In order to determine the forming force in deep drawing and backward extrusion
processes (on Al 99.5F7 specimens) the analytical, numerical and stochastic modeling and analysis
of forming force on the basis of the Box-Wilson’s multi factorial experimental designs by use of
rotatable experimental design were carried out. The goal of the paper is to predict the force in these
different forming processes giving identical parts by means of different modeling approaches. This
study will seek to compare the results of these modeling solutions with experimental results serving
to check the correction and the verification of analytic, stochastic and numerically obtained results.
Also, the scope of the present paper is to evaluate different parameters affecting these processes and
to examine some experimental procedures in laboratory scale for the listed material in order to give
more useful information in numerical and stochastic computations and also, to define the
correlation among the parameters of these processes in order to improve the existing one and to
raise it to a higher techno economic level. The increasing tendency for industrial parts cost
reduction, quality improvement, materials savings, and the shortening of design and manufacturing
time is more focused on this way of analysis of processes. These investigations are a basis for
general conclusions about the forming force and they have a direct application in the projecting of
these processes, tools and forming systems.
Abstract: A multi-stage stamping process of one-piece automobile steel wheels from tubes was
developed to decrease the loss of material for the blanking. In this process, the tube is nosed into a
cup with a central hole, and then the taper bottom and side wall of the cup are formed into disk and
rim portions of the wheel, respectively. The tube is produced by bending a rectangular sheet into a
tube and by welding both edges of the bent sheet to prevent the loss of material for the blanking.
The stamping sequence of the one-piece wheels was designed by finite element simulation. The
central hole of the cup was decreased to a desired diameter of the hub hole without buckling and
wrinkling by a 5-stages nosing operation. The taper bottom of the cup was reversely drawn, and
then was flared without folding by 2 stages. The wall thickness of the formed wheel was thick and
thin in the disk and rim portions, receptively, and thus the requirement of strength of wheels is
satisfied. A one-piece wheel having a hub hole was successfully formed by the designed sequence
in a miniature experiment.
Abstract: In recent years a steadily growing interest in applying lightweight construction concepts
could be observed. This development is accompanied by an increasing demand for innovative
forming strategies suitable for extending the forming limits of the typical lightweight materials.
Deep drawing combined with an integrated electromagnetic calibration step is an example of such a
technology. The feasibility and potential of this process combination is analyzed on the basis of a
demonstrator part from the automotive industry. Thereby, aspects related to the practicability of the
electromagnetic forming process itself are regarded as well as points related to the deep drawn
preform. The concept of a 3D-coil insert, integrated into a deep drawing punch in order to realize
the calibration in the deep drawing process, is introduced and based on the experimental results,
conclusions regarding the applicability of the process combination are drawn.
Abstract: Aircraft engine components are assemblies of several parts that are manufactured using
various processes: deep drawing and machining, among others. Deep drawing cannot control
accurately wall thicknesses and is performed in numerous steps. Machining parts from solids is less
and less cost effective as prices for raw materials increase. Hence, the use of near net shape
manufacturing methods is becoming more appealing. An alternative forming process is here
investigated: flowforming, process well adapted to axisymmetric parts. The amount of forming
steps, welding and machining could be significantly reduced, reducing lead-times and
manufacturing costs. Examples are presented for the forming of selected parts (gas generator cases,
fan cases and diverter ducts), together with their metallurgical and mechanical properties.
Flowforming, however, can only generate shells with some hollow details: most flanges, bosses,
stiffeners or weld lips cannot be obtained. Hence, methods of adding material are explored.
Abstract: In order to value the process of variables influence in sheet metal hydroforming, a special
hydroforming cell has been developed. Generally, sheet hydroforming is obtained using appropriate
press tooling. This option requires large investments completely dedicated to this technology of
production. As an alternative, conventional hydraulic presses can be used for sheet hydroforming in
combination with special hydraulic tooling named “hydroforming cells”. A special “hydroforming
cell” concept has been developed to perform experimental analysis for different shapes using the
same tooling set up. CAE tools had a strategic role just to develop the best layout and to find the
optimum solutions for the process variables. FEA has been used to define the distribution of the
blank holder variable forces: a solution which implies the use of twelve independent actuators have
been implemented. The position and the load path of each one of them has been chosen for each
formed shape, in accordance with the FEA results. Customized actuators have been used to solve
interferences between mechanical parts of the hydroforming cell. For this specific aspects the
virtual 3D design was necessary for the appropriate decisions. The developed process system is
very effective so that is possible to set up experimental campaigns for sheet hydroformed
Abstract: The filling of the die corner in hydroforming of a tube with a box die was improved by
controlling wrinkling under oscillation of internal pressure. In this process, a small wrinkle occurs
near the die corner in the former stage, and then the wrinkle is eliminated in the latter stage because
the flat bulge appears in the former stage due to the oscillation of internal pressure. A hydroforming
process of steel tubes with a box die was performed in both three dimensional finite element
simulation and experiment. The filling of the die corner for the mean linear pressure was not sufficient
due to large wrinkles appearing in the former stage, whereas bursting occurs for the peak linear
pressure due to round bulging. On the other hand, the uniformity of wall thickness of the formed tube
was improved by the pulsating pressure.
Abstract: In this paper, the flexforming process is modeled by finite element method in order to
investigate the operation window of the problem. Various models are established using explicit
approach for the forming operation and implicit approach for the unloading one. In all analyses the
rubber diaphragm has been modeled revealing that the modeling of this diaphragm is essential.
Using the material Aluminum 2024 T3 alclad sheet alloy, three basic experiments are conducted:
Bending of a straight flange specimen, bending of a contoured flange specimen and bulging of a
circular specimen. By these experiments the effects of blank thickness, die bend radius, flange
length and orientation of the rolling direction of the part have been investigated. Experimental
results are compared with finite element results to verify the computational models.
Abstract: The possibility to produce lightweight components with a complex geometry enhanced,
in the last decades, the industrial application of the tube hydroforming and, more recently and
restricted to specific industrial fields, of the sheet hydroforming technology. The integration in one
tool of a tube and a double sheet hydroforming process represents an innovative technology which
further emphasises the advantages offered by hydroforming in terms of costs reduction and
complexity of the manufactured part. This paper describes the design and the construction of a
complex hollow part resulting from the simultaneous hydroforming of two sheets and a tubular
component in one tool. The focus is set in particular on the optimisation of the joining zone between
tube and sheet pair, whose geometry allows a “metallic” sealing of the gap between the sheets and
the tube, i.e. without using sealing components. The contact between tube and sheet pair allows the
transmission of the axial force used to support the bulging of the tube to the sheet blanks, thus
increasing their draw-in in the die and, consequently, avoiding the occurrence of tearing on the part.
The paper describes the optimisation of different process parameters like the shape and the
dimension of the blanks, their initial positioning in the tool, the value of the axial force applied to
the tubular component and the blankholder force during the preforming and the calibrating stages.