Metal working – Method of mechanical manufacture – Assembling or joining
Patent
1996-03-01
1998-05-19
Bryant, David P.
Metal working
Method of mechanical manufacture
Assembling or joining
2952506, 2924353, 29798, B23P 1100
Patent
active
057523053
DESCRIPTION:
BRIEF SUMMARY
This invention relates to self-piercing riveting and more particularly to a method of and apparatus for riveting of the kind in which a self-piercing rivet is inserted into sheet material without full penetration, such that the deformed end of the rivet remains encapsulated by an upset annulus of the sheet material.
FIG. 1 is a diagrammatic section of an example of a riveted joint made by such a riveting method in accordance with the invention. A rivet 1 has a head 2 and a shank 3 terminating in an annular edge 4. The shank 3 is initially cylindrical but is flared outwardly into the illustrated shape as the rivet is driven into two overlapping sheets 5, 6 located on a suitably shaped die. As shown, the shank 3 and the edge 4 of the rivet remain embedded in the sheet material 5, 6 after the rivet has been set.
Hitherto, riveted joints of the kind illustrated in FIG. 1 have had various imperfections. Desirably, the head 2 of the rivet 1 is flush with the surrounding surface of the sheet 5 which should remain undeformed, and the annular valley 7 between the sheet 5 and the rivet head 2 should be as shallow as possible. In reality, however, the riveting stresses may cause substantial deformation of the upper sheet 5, for example in the form of a circular depression or dimple around the rivet location, and the valley 7 may be unacceptably deep. Although unobjectionable in many applications, such surface distortions are often unacceptable, e.g. for visible joints of motor vehicle body panels, in particular the curved portions of said panels. On the concealed side of the joint, the appearance is immaterial but unevennesses in the thickness of the sheet material 6 encapsulating the rivet end 4 may affect the strength of the joint and permit breakthrough of the rivet end thereby encouraging corrosion.
It will be appreciated that self-piercing riveting is not confined to rivets of the kind shown in FIG. 1. Thus, for example, flat head and pan head style rivets may be used but riveted joints using such alternative rivets have hitherto suffered from at least some of the imperfections mentioned above.
It is an object of the present invention to provide a method of self-piercing riveting of the kind defined in which the aforesaid disadvantages are obviated or mitigated.
The invention also relates to a riveting machine for setting self-piercing rivets in the manner described. A known riveting machine for setting self-piercing rivets is described in U.S. Pat. No. 4,615,475 by Nietek Pty. Ltd. the disclosure of which is incorporated herein by reference.
It is a further object of the present invention to modify the known riveting machine so as to improve the riveted joint produced thereby.
According to a first aspect of the present invention there is provided a method of riveting comprising inserting a self-piercing rivet into sheet material without full penetration such that the deformed end of the rivet remains encapsulated by an upset annulus of the sheet material characterised in that the sheet material is clamped with a substantial force during the riveting operation in the region around the rivet insertion location.
According to a second aspect of the present invention there is provided a riveting machine for inserting a self-piercing rivet into sheet material without full penetration such that the deformed end of the rivet remains encapsulated by an upset annulus of the sheet material, said machine comprising a punch, means for feeding rivets successively to the punch for insertion into sheet material to be riveted, a die aligned with the punch for deforming the rivet inserted thereby, and clamping means for clamping the sheet material with a substantial force during the riveting operation in the region around the rivet insertion location.
The invention will now be further described by way of example only with reference to the accompanying drawings in which:
FIG. 1 is a section of a riveted joint made by the riveting method of the invention;
FIG. 2 is a diagram showing the operative components of a riveting machine o
REFERENCES:
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patent: 4911592 (1990-03-01), Muller
patent: 4999896 (1991-03-01), Mangus et al.
patent: 5060362 (1991-10-01), Birke et al.
patent: 5277049 (1994-01-01), Endo
Engineering, vol. 222, No. 9, Sep. 1982, London, GB, "Trends in Fastener Design", p. 635, Fig. 3.
Blacket Stuart Edmond
Cotterill Alf
Singh Sumanjit
Bryant David P.
Henrob Limited
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