ArticlePublisher preview available

Joining of Aluminium Alloy and Mild Steel Sheets Using Mechanical Clinching

Trans Tech Publications Ltd
Materials Science Forum
Authors:
To read the full-text of this research, you can request a copy directly from the authors.

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.
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
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans
Tech Publications Ltd, www.scientific.net. (Research Gate for subscription journals-09/02/24,18:26:54)
... Abe performs in [14] Finite Elements Simulations of the respective shape changes on the basis of aluminum and mild steel combinations and verifies this with experimental investigations. The degree of strain hardening and the geometric dimension of the individual areas determine the property profile of the joint as a function of the subsequent load case. ...
Article
Full-text available
The work carried out is based on the thesis properties of clinched joints are determined by the proportions of binding mechanisms form-closure, force-closure and material-closure. To describe the acting binding mechanisms and thus to derive the joint properties, detailed knowledge of the local effect of the individual binding mechanisms is necessary to ensure their targeted adjustment by the joining process. The targeted setting of different proportions of the binding mechanisms is achieved firstly via tool geometry and secondly via surface condition of the joined parts. An introduced form-closure component can be quantified by metallographic cross section with subsequent measurement of the quality-determining parameters such as undercut, penetration depth and neck thickness. To qualify the force-closure component, a torsional load can be applied mechanically at rotationally symmetrical clinch joints. This also allows the influence of different surface conditions on the tribological system to be quantified. Measurement of electrical resistance can reveal the binding mechanisms of force- and material-closure. These investigations are carried out on an aluminum joining part combination of the same type. As a result of these investigations, the clinched joints can be designed according to the load occurring in the later life cycle in the form of an optimum and compromise variant with regard to minimum loads to be transmitted mechanically, electrically with regard to low resistance or manufacturing with minimum energy input.
... However, due to the different properties of these materials their joining with the traditional welding process is not possible. Today, a large number of alternative joining technologies is emerging, or is already in use, to meet the growing need in joining such materials [4] to [9]. A review of such technologies and their use can be seen in [10] to [12]. ...
Article
Full-text available
In the development of new joining technologies, incorporation of mechanical joints in computer analyses for the evaluation of structures can be carried out by a practical, simplified mechanical joint model. Here, two most frequently used joining technologies were analysed, a self-piercing rivet joint and a clinch joint. Physical tests of static load capacity of the joints were performed and numerical models for simulations were set-up. An optimization method was designed for estimating the material parameters of the mechanical joint for the needs of numerical analyses. For optimization purposes during the plan of experiments, a range of possible parameter values was investigated using a response surface method, results of simulations, results of physical tests and a genetic algorithm. The results of simulations using the optimal values of the material parameters are comparable to the experimental observations for the both joints.
... The joinability for the clinching of aluminum alloy sheets and steel sheets was investigated by Abe et al. [44]. The study found that the upper sheet is prone to fracture when the lower sheet is hard. ...
Article
Full-text available
Clinching technology can join thin sheets of various materials, including aluminum alloy, magnesium alloy, steel, titanium alloy, and polymers. Nowadays, with the popularization of the lightweight concept and the application of various sheet materials in manufacturing, clinching technology has highlighted the advantages of being able to adapt to the joining of different sheet materials. With its unique advantages, clinching technology gains wide development space in the field of metal sheet connection. The application of clinching technology in various sheet materials is summarized and analyzed. The clinching process of special materials is also discussed. In addition, some unaddressed issues in the clinching process of special materials are identified in this paper.
... Eshtayeh describes in [5] the clinching process of dissimilar joining partners in general. Especially the joining of aluminum and mild steel [6], the advanced high-strength steel DP780 and Al5052 alloy [7], or the Al5052 alloy with steel grades up to 1000 MPa tensile strength in [8] also with adaption of the die tools [9] and hot dip coated surfaces [10] are state of the art. Furthermore, copper materials or mixed compounds of aluminum and copper for electrical applications can also be clinched [11]. ...
Article
Full-text available
The multi-material design and the adaptability of a modern process chain require joining connections with specifically adjustable mechanical, thermal, chemical, or electrical properties. Previous considerations primarily focused on the mechanical properties. The multitude of possible combinations of requirements, materials, and component- and joining-geometry makes an empirical determination of these joining properties for the clinching process impossible. Based on the established and empirical procedure, there is currently no model that takes into account all questions of joinability—i.e., the materials (suitability for joining), design (security of joining), and production (joining possibility)—that allows a calculation of the properties that can be achieved. It is therefore necessary to describe the physical properties of the joint as a function of the three binding mechanisms—form closure, force closure, and material closure—in relation to the application. This approach illustrates the relationships along the causal chain “joint requirement-binding mechanism-joining parameters” and improves the adaptability of the mechanical joining technology. Geometrical properties of clinch connections of the combination of aluminum and steel are compared in a metallographic cross-section. The mechanical stress state of the rotationally symmetrical clinch points is qualified with a torsion test and by measuring the electrical resistance in the base material, in the clinch joint, and during the production cycle (after clinching, before precipitation hardening and after precipitation hardening).
... Numerous different solid state welding methods have been considered, including friction stir welding, 6,7) friction welding, 8,9) explosive welding, 10) diffusion bonding, 11) roll bonding, 12) stud junction, 13) and mechanical joining methods. 14,15) Magnetic pulse welding (MPW) is also a type of solid state welding. 16) Up to now, MPW has been applied to welding between similar metals, such as industrial pure aluminum sheets, 17) Cu sheets, 18) and 2000-series Al alloy sheets, 19) as well as to welding between dissimilar metals, including industrial pure aluminum sheets and Cu sheets 20) and 6000-series Al alloy sheets and steel sheets. ...
Article
The 6061-T6 sheet and the DP 780 steel sheet were joined under the condition with the gap length d of 1.17 to 1.42 mm and discharge energy W of 3.0 kJ. The impact speed ranged from 430 to 460 m/s. The weld width showed a tendency to increase due to the increase of the collision speed. However, when the gap length exceeds 1.59 mm (impact speed of >460 m/s), the weld width became narrow. Considering that the electromagnetic force continues to apply on the flyer sheet after collides with the fixed sheet, it is desirable to perform the welding in a time shorter than the time tm when the collision time reaches the maximum current value. Therefore, the collision time is considered to be one of factors that affect the welding condition. As a result of experiments in consideration of above conditions, it was possible to achieve a strong lap joint of the 6061-T6 sheet and the DP 980 steel sheet, although the welding condition was limited as compared with the case of the DP 780 steel sheet. Thus, sound lap joint between 6061-T6 sheet and high-tensile steel sheet with 1 GPa class was achieved by magnetic pulse welding. This Paper was Originally Published in Japanese in J. JILM 69 (2019) 541–547. Fig. 12 Welding interface microstructure of the 6061-T6/DP980 steel lap joint sheet (W = 3.0 kJ, d = 1.17 mm). (a) SEM image, (b) Fe mapping, (c) Al mapping, (d) IQ map, (e) IPF map, and (f) KAM map. Fullsize Image
... Using finite element simulation and experiment, the deformation behavior of two laminates in the connection process was observed to avoid the occurrence of defects. The results [64] showed that the fracture and the necking and separation of the upper plate were caused by the excessive thinning of the upper and lower steels, respectively. Song et al. [65] investigated the mechanical properties and the failure behavior of the steel-aluminum clinched joint under various test conditions. ...
Article
Full-text available
Clinching technology is a mechanical connection technology that is applied to connect metal or non-metal sheet materials. It is widely used in different applications, such as automobile, aircraft, household appliances and other industries. In order to reduce weight, save energy, reduce fuel consumption, reduce pollution and curb global warming, lightweight structures with clinched joint are increasingly used in transportation. The finite element technology is popularized in engineering, so that it can get similar results with the test after investing less time, manpower, energy and material resources, which is conducive to the prediction and smooth progress of the test. A review of the finite element analysis of clinching technology is provided in the present paper. The article’s work also discusses the strength of the clinched joint, the factors influencing the clinched joint’s strength, the failure mechanism of the clinched joint, etc. Furthermore, the novel technologies of clinching as well as the finite element models and methods used in clinching, are introduced. The present paper’s main objective was to review the recent developments in the finite element analysis of clinching and provide a basis for further investigation in this area of research.
... He [3] reviewed the mechanical clinching process, and various research works have been conducted. Mechanical clinching processes are developed to join aluminium alloy sheets [4], high-strength steel sheets [5], ultra-high-strength steel sheets [6], boron steel sheets in hot stamping [7], aluminium alloy and mild steel sheets [8], aluminium alloy and high-strength steel sheets [9], carbon fibre-reinforced plastic and aluminium alloy sheets [10], and steel sheet and aluminium casting [11], respectively. Although some technologies such as local cutting and upsetting of the sheets with rectangular tools are used in some mechanical clinching processes, round clinching is very common. ...
Article
Full-text available
To increase the usage of high-strength steel and aluminium alloy sheets for lightweight automobile body panels, the joinability of sheet combinations including a 780-MPa high-strength steel and an aluminium alloy A5052 sheets by mechanical clinching and self-pierce riveting was investigated for different tool shapes in an experiment. All the sheet combinations except for the two steel sheets by self-pierce riveting, i.e., the two steel sheets, the two aluminium alloy sheets, and the steel-aluminium alloy sheets, were successfully joined by both the joining methods without the gaps among the rivet and the sheets. Then, to show the durability of the joined sheets, the corrosion behaviour and the joint strength of the aged sheets by a salt spray test were measured. The corrosion and the load reduction of the clinched and the riveted two aluminium alloy sheets were little. The corrosion of the clinched two steel sheets without the galvanized layer progressed, and then the load after 1176 h decreased by 85%. In the clinched two galvanized steel sheets, the corrosion progress slowed down by 24%. In the clinched steel and aluminium alloy sheets, the thickness reduction occurred near the minimum thickness of the upper sheet and in the upper surface on the edge of the lower aluminium alloy sheet, whereas the top surface of the upper sheet and the upper surface of the lower sheet were mainly corroded in the riveted joint. The load reduction was caused by the two thickness reductions, i.e., the reduction in the minimum thickness of the upper sheet and the reduction in the flange of the aluminium alloy sheet. Although the load of the clinched steel without the galvanized coating layer and aluminium alloy sheets decreased by about 20%, the use of the galvanized steel sheet brought the decrease by about 11%. It was found that the use of the galvanized steel sheets is effective for the decrease of strength reduction due to corrosion.
Article
The GA steel sheets with various strengths (590, 780, and 980 MPa classes) from which the Zn-Fe film was removed and 6061-T6 sheets were lap joined magnetic pulse welding under the conditions of gap length d of 1.17 mm and discharge energy W of 3.0 kJ. Before welding the GA steel sheets, a Zn-Fe film with a width of 5 mm was removed by grinding or acid treatment. In the case of acid treatment with dilute sulfuric acid, the film was removed within 3 minutes. On the other hand, when the film was removed by grinding, burrs were formed on the GA steel plate side. With either film removal method, the film was removed and a lap joint between GA steel sheet and 6061-T6 sheet was able to be achieved. This means that the joining position can be selected by magnetic pulse welding. The corrosion resistance of the lap joint sheets was investigated through salt spray test for 120-hours. The results showed that even under conditions where GA steel plates corrode, the weld interface did not corrode and bonding strength remained as well as before the corrosion test.
Article
Purpose Describes how Jaguar Cars in the UK is assembling aluminium car bodies for its new XK sports car that will be manufactured with a production time of 12 hours. Design/methodology/approach Describes the major production line techniques that are used in the assembly of the body‐in‐white structure. These include adhesive bonding, self‐piercing rivets (SPRs) and self‐tapping screws. Findings The use of SPRs and self‐tapping screws is proving essential in the joining of aluminium components manufactured as extrusions, castings and pressings. Research limitations/implications The introduction of adhesive bonding, SPRs and self‐tapping screws is the result of considerable research work on the part of Jaguar engineers and the company's suppliers. This work is likely to continue in order to reduce cycle times and improve overall product performance, both in terms of manufacture and for the user. Practical implications It is likely that arising out of development work into new assembly techniques that the technology will be used throughout the Ford organization, including other companies that form the Premier Automotive Group. Both Aston Martin and Volvo could benefit from the technologies developed at Jaguar Cars. Originality/value This is the first time that Jaguar Cars has used self‐tapping screws to join aluminium components although it has been used before within Lotus Group for the Elise sports car.
  • P Reinhert
P. Reinhert: Alum. Int. Today, Vol.16-1 (2004), p.21-22, 24.
  • A Elrefaey
  • M Takahashi
  • K Ikeuchi
A. Elrefaey, M. Takahashi and K. Ikeuchi: J. Japan Welding Society Vol. 23-2 (2005), p. 186-193.
  • Y Abe
  • T Kato
  • K Mori
Y. Abe, T. Kato and K. Mori: J. Mater. Process. Technol. 177-1-3(2006), p. 417-421.
  • J Varis
J. Varis: J. Mater. Process. Technol. Vol. 132-1-3 (2003), p. 242-249.
  • J Varis
J. Varis: J. Mater. Process. Technol. Vol. 172 (2006), p. 130-138.