Metal working – Method of mechanical manufacture – Assembling or joining
Patent
1993-10-13
1995-05-16
Vo, Peter Dungba
Metal working
Method of mechanical manufacture
Assembling or joining
29 34B, 2924354, 295252, B21J 1502, B21J 1536
Patent
active
054149215
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a process for riveting together objects, in which a rivet with a head and a rivet shaft is inserted with its rivet shaft into holes in the object, whereafter the rivet is compressed between a riveting tool and a holder-on, so that a second rivet head is formed on the side of the objects opposite to the side on which the first-mentioned head is located.
The invention also relates to a tool for carrying out said process.
BACKGROUND OF THE INVENTION
In conventional yoke riveting with homogenous rivets, the rivet is compressed between a pair of flat surfaces on the riveting tool and on the holder-on. The deformation essentially reshapes the free end of the rivet shaft extending out from the objects into its second rivet head. This means that the diameter of the rivet shaft must be carefully adapted to the diameter of the holes in the objects so that there will be no gap in the rivet fastening. When fastening together objects of varying thicknesses, rivets of varying lengths must be used. This places requirements of the skill of the riveter and involves a risk of faults especially when there is very little difference in length between the different rivets to be used. The need to use rivets of varying lengths also means that it is not possible to rivet several rivets at the time with the same tool. Rather, the rivets must be compressed one at the time or with a number of rivet yokes at the same time.
The risk of gaps arising in a rivet fastening between for example a pair of sheet metal pieces is greater in those cases where the holes have been punched in the sheet metal pieces than when they have been drilled since punched holes will always be slightly conical with a smaller diameter at the entry side of the punch and the larger diameter on the die side.
SUMMARY OF THE INVENTION
The purpose of the present invention is to provide a riveting process and a tool making it possible to use rivets of a single length and diameter for various thicknesses and hole diameters within a certain thickness interval of sheet metal combinations which are to be riveted together.
This is achieved according to the invention in a process of the type described by way of introduction by virtue of the fact that the rivet is compressed between a riveting tool and a holder-on creating a force pattern in the rivet shaft, which strives to expand the rivet shaft radially in connection with the forming of the other rivet head.
A tool for carrying out the riveting process is characterized in that at least the riveting tool has a pressing surface with a central raised portion surrounded by a flat angular portion.
By using a tool which causes the rivet shaft to swell before the head is formed, a single dimension of rivet can be used for varying hole diameters, since the initial deformation of the rivet results in a radial filling of the hole. This in turn means that a single rivet link can be used for different thicknesses of rivet fastenings by virtue of the fact the required amount of material for the rivet head can be controlled by adjusting the hole diameter, i.e. a large diameter rivet hole is provided when the combined thickness of the objects to be fastened together is small.
Thus the need in production to select rivets of varying lengths within a certain interval is eliminated and a number of rivets can be compressed in a pressing operation with a single tool.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described in more detail with reference to examples shown in the accompanying drawings, where FIG. 1 shows a rivet between a schematically shown riveting tool and a holder-on, FIG. 2 shows a section through the tool components in FIG. 1 prior to and after riveting of a pair of sheet metal pieces, FIG. 3 is an enlargement of the encircled area in FIG. 2 and FIG. 4 is a cross section through an apparatus for riveting together a U-beam with tie plates.
DETAILED DESCRIPTION OF THE INVENTION
In FIGS. 1-3, 1 designates a riveting tool and 2 a holder-on for counterhold,
REFERENCES:
patent: 2654272 (1953-10-01), Warren
patent: 2925748 (1960-02-01), Ross
patent: 3543985 (1970-12-01), Adolphi
patent: 4221041 (1980-09-01), Hufnagl et al.
patent: 4864713 (1989-09-01), Roberts et al.
Dungba Vo Peter
Press & Platindustri AB
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