WO1985005414A1

WO1985005414A1 - Rivets

Info

Publication number: WO1985005414A1
Application number: PCT/GB1985/000207
Authority: WO
Inventors: John Michael Wright
Original assignee: The Bifurcated And Tubular Rivet Company Limited
Priority date: 1984-05-16
Filing date: 1985-05-16
Publication date: 1985-12-05
Also published as: GB2172951A; ES286769Y; EP0181881A1; GB8600808D0; GB8412432D0; AU4353985A; GB2172951B; ZA853753B; ES286769U

Abstract

A self-piercing rivet comprises a head (11) and a shank (3). The shank has a circular external profile and is formed with a hexagonal poke (4) whereby zones of weakness are formed at each apex of the hexagon. The poke (4) has an angled lead-in (8) so that as the rivet is set a radially outward force is produced on the wall of the poke causing the poke to split along the zones of weakness. Rose setting is thus obtained without the use of a profiled setting tool.

Description

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RIVETS

This invention relates to a rivet, and in the preferred embodiment provides a rivet which can readily be set without the use of a profiled setting die. 5 Rivets comprising a head, a shank, and a poke extending into the shank from the end thereof remote from the head are known. In the prior art, such rivets have been so called "roll set" or "rose set". In roll setting, the material of the

10 shank is rolled outwardly by means of a suitable setting die , and in rose setting the material of the shank has been split longitudinally to form a plurality of tongues which are each bent outwardly by means of a suitable setting die. Roll setting suffers from the

15 disadvantage that a substantial setting load is required, whilst rose setting suffers from the disadvantage of requiring the use of a relatively expensive setting die capable of splitting the material of the rivet. Both methods have sufferred from the

20 disadvantage that a setting die is required which must be accurately axially aligned with the shank of the rivet . This has necessitated the use of heavy machine frames to enable the setting die to be accurately, positioned, and maintained in position during

25 repeated setting operations. According to the present invention there is provided a rivet having a head, a shank, and a poke, the poke extending into the shank from the end thereof remote from the head whereby the end region of the 5 shank remote from the head is annular, wherein the annular region of the shank includes a plurality of longitudinally extending zones of weakness along which the material of the shank will split when the annular region is forced radially outwardly.

1 With such a rivet the use of a setting die having sharp edges for splitting the material of the rivet is obviated, and the rivet may be rose set simply by applying a radially outward force to the annular zone on the shank. Setting in this manner

15 requires a smaller setting load than is required to roll set a comparable rivet, and accordingly the rivet can be set by a smaller machine. Further, the individual legs into which the annular region of the shank splits can readily be spread

2 thereby improving the tensile strength of the set rivet.

The zones of weakness can conveniently be provided by making the outer surface of the shank circular in transverse cross-section, and by making

--5 the poke polygonal. Thus, at each apex of the polygon the thickness of the material of the shank is a minimum, and a zone of weakness is formed. In the preferred embodiment the cross-section of the poke is a regular hexagon. In this case, the material of the shank will split into six legs during setting, thereby providing for a six leg rose setting of the rivet.

Preferably, the free end of the shank, i.e. the end remote from the head, extends obliquely 5 to the axis of the shank from an edge at the outer periphery of the shank radially inwardly and axially towards the head. In this manner, an angled lead-in to the poke is provided, and as the rivet is forced into the item to be riveted, the end of the shank acts as a cam surface, causing a radially outward^' force to be applied to the annular part of the shank. This radially outward force is sufficient to split the material of the shank along the zones of weakness. In this way, a rose set can be obtained using a flat bottom anvil, i.e. the need for a profiled bottom setting die is completely eliminated. This has a number of advantages. Firstly, the combination of the rose set and the use of a flat bottom anvil leads to relatively little displacement of the material being riveted on the rear side of the joint. The relatively high tooling costs associated with the profiled bottom die usually required for rose setting is eliminated, and the set-up time for riveting machines is greatly reduced since the need to align accurately the top and bottom tooling is removed. Since no accurate alignment of top and bottom tooling is required a relatively lighter machine frame can be used.

In one embodiment a passage extends from the poke through the shank and head of the rivet. Thus, the passage and poke together form a through hole in the rivet. When the rivet is being used as a self-piercing rivet the hole provides an aperture for the escape of displaced component material. This again assists in reducing the material displacement of the rear side of the joint and further reduces the setting load required to form a low profile joint. The displaced material which fills the through passage of the set rivet resists inward movement of the material of the shank thereby improving the strength and particularly the shear strength, of the rivet. In an alternative embodiment the head of the rivet is solid, and material displaced during setting is not visible from the head side of the riveted material.

The above and further features and advantages of the invention will become clear from the following des¬ cription of preferred embodiments thereof given by way of example only, reference being had to the accompanying drawing wherein:

Figure 1 shows a side view of a preferred embodi- ment of self-piercing rivet;

Figure 2 is a bottom plan view of the rivet of Figure 1; and

Figure 3 is an axial cross-section of a second embodiment. The rivet 1 shown in Figures 1 and 2 comprises a head 2 and a shank 3 • A poke 4 extends from the end 5 of the rivet remote from the head 2 into the shank to approx¬ imately half the depth of the shank.

As will be seen particularly from Figure 2 the outer periphery of the shank 3 is circular in transverse cross-section, whilst the poke 4 is hexagonal in transverse cross-section. Accordingly, at each apex of the poke the material of the shank is relatively thin, thereby defining a zone of weakness 6. It will be appreciated that the use of a hexagonal poke provides six zones of weakness 6 symmetrically disposed about the shank 3 •

The free end of the shank 5 extends obliquely to the longitudinal axis of the shank from an edge 7 defined at the periphery of the shank radially inwardly and axially towards the head. Accordingly, an angled lead-in surface 8 is formed extending from the edge 7 to the poke 4• It will be appreciated that if the rivet 1 is used as a sel -piercing rivet, as the rivet is forced into material to be riveted, the surface 8 acts as a cam surface causing a radially outward force to be applied to the end region of the shank.

If the material to be riveted is supported against a flat anvil, the radial force generated by the earning action will be sufficient to split the shank along the zones of weakness 6, thereby rose setting the rivet without the use of a profiled setting die.

A passage 9 extends from the poke through the shank and head of the rivet, the passage 9 and poke 4 together defining a through-hole in the rivet. When the rivet is used as a self-piercing rivet in association with a flat bottom anvil as described above the through hole provides a space for material displaced by the rivet. This not only reduces the setting force required and reduces the amount of material displacement on the tail side of the set joint, but also assists in strengthening the rivet since the displaced material will fill the through hole, thereby resisting both tensile and shear deformation of the set rivet.

The rivet 10 shown in Figure 3 is similar to that of Figures 1 and 2 in that it includes a shank 3 which has a circular external profile, a hexagonal poke 4, and an angled lead-in surface 8. However, the head 11 of the rivet is solid whereby material displaced during setting is not visible from the head-side of the riveted material. In this case, the poke is tapered slightly in order to ease manufacture and to reduce setting loads. A tapered poke may, if desired, be used in the embodiment of Figures 1 and 2.

It will be appreciated from the above description that the rivets illustrated in the drawings may be used as self-piercing rivets which can be rose set using only the setting load applied to the head of the rivet and a^' flat anvil to support the material being riveted.

Claims

1. A rivet having a head, a shank,^' and a poke, the poke extending into the shank from the end thereof remote from the head whereby the end region of the shank remote from the head is annular, wherein the annular region of the

5 shank includes a plurality of longitudinally extending zones of weakness along which the material of the shank will split when the annular region is forced outwardly.

2. A rivet according to claim 1 wherein the outer 0 surface of the shank is circular in transverse cross- section, and the poke is polygonal in transverse cross- section whereby at each apex of the polygon the thickness of the material of the shank is a minimum and a zone of weakness is formed. 5

3. A rivet according to claim 2 wherein the poke is a regular hexagon in transverse cross-section.

4_* A rivet according to any preceding claim wherein 0 the free end of the shank extends obliquely to the axis of the shank from an edge at the outer periphery of the shank radially inwardly and axially towards the head to provide an angled lead-in to the poke.

-5 ζ . A rivet according to any of claims 1 to 3 wherein a passage extends from the poke through the shank and head of the rivet, the poke and passage together forming a through hole in the rivet.

0 6. A rivet according to any of claims 1 to 3 wherein the poke is tapered and has a maximum size at the free end of the shank.