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Joining of Aluminium Alloy and Mild Steel Sheets Using Mechanical
Clinching
Y. Abe1,a, T. Kato2,a and K. Mori1,c
1) Department of Production Systems Engineering, Toyohashi University of Technology
Hibarigaoka 1-1, Tempaku-cho, Toyohashi, Aichi, Japan
2) Department of CAE, Nippon POP Rivets and Fasteners Ltd, Aichi, JAPAN
a) abe@plast.pse.tut.ac.jp, b) kato-t@popnpr.co.jp, c) mori@plast.pse.tut.ac.jp
Keywords: Joining; Mechanical fastening; Mechanical clinching; Aluminium alloy sheet; FEM
simulation.
Abstract. The aluminium alloy and mild steel sheets were joined with mechanical clinching.
Deforming behaviour of the two sheets during the clinching was observed from finite element
simulation and an experiment to avoid defects. The fracture of the upper sheet, necking and
separation are caused by the small upper sheet thickness in the thick total thickness, the small lower
sheet thickness in the thick total thickness and the small lower sheet thickness, respectively. The
joining range for the combination of the upper aluminium alloy sheet of and the lower steel sheet of
is larger than that of the reverse combination. The effect of the difference between the flow stresses
of the two sheets on the deformation behaviour was examined.
Introduction
The reduction in the weight of automobiles, the use of aluminium alloy sheets tends to increase
because of high specific strength [1, 2]. Since both steel and aluminium alloy sheets are generally
used for automobiles, the joining of the steel and aluminium alloy sheets is required. Although the
resistance spot welding is usually used to join steel sheets for automobile body panels, the welding
of aluminium alloy sheets is not easy because of the high thermal conductivity and low melting
point. Moreover, it is not easy to weld aluminium alloy and steel sheets together, because the two
melting points are very different. It is desirable in the automobile industry to develop new joining
processes of aluminium alloy and steel sheets.
To join aluminium alloy and steel sheets, the spot friction stir welding [3], the self pierce riveting
[4,5] and the mechanical clinching [6] have been developed. The spot friction stir welding is a
joining process using frictional heat generated by a rotating tool, and the speed is not high enough
to join a lot of points in automobile body panels. The self pierce riveting is a cold process for
joining two sheets by driving a rivet through the upper sheet and upsetting the rivet in the lower
sheet without penetration into the lower one. Although the difference between the melting points of
the two sheets is not a problem because of the cold process, the low running costs become relatively
high due to use of rivets [7]. In the mechanical clinching, the sheets are joined by cold local
hemming with a punch and die. The mechanical clinching has the advantage of low running costs
due to no rivets. Although the mechanical clinching is conventionally employed for joining of
aluminium alloy sheets, the clinching has the ability to joining of dissimilar sheet metals such as
aluminium alloy and steel sheets.
In the present study, the deformation mechanism in the mechanical clinching of aluminium
alloy and mild steel sheets was investigated from finite element simulation and an experiment. The
effect of the difference between the flow stresses of the two sheets on the deformation behaviour
was examined.
Conditions of Mechanical Clinching
In the mechanical clinching, the two sheets are mechanically joined by forming an interlock
between the lower and the upper sheets with the punch and die as shown in Fig. 1. The strength of
Materials Science Forum Online: 2007-10-02
ISSN: 1662-9752, Vols. 561-565, pp 1043-1046
doi:10.4028/www.scientific.net/MSF.561-565.1043
© 2007 Trans Tech Publications Ltd, Switzerland
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