GB2214120A - Rivet-setting tools and gripping jaws therefor - Google Patents

Abstract

Jaws for rivet-setting tools are provided with asymmetrically-spaced teeth 5, 5' to concentrate the load applied to a mandrel by each tooth. In one preferred arrangement (Fig 3, not shown) the teeth in one jaw are out of register with those in the opposing jaw so that the tendency of the mandrel to distort within the jaw length further reduces slipping tendencies. The tool is particularly suitable for setting rivets of so-called difficult materials such as stainless steel. <IMAGE>

Description

RIVET-SETTING TOOLS AND GRIPPING JAWS THEREFOR The present invention relates to rivet-setting tools for mandrel rivets of the pull-to-set type, and in particular to the gripping jaws of such tools.

Pull-to-set rivets are set from one side of a workpiece to be riveted by inserting the flanged body of a blind rivet into a hole and collapsing the body of the rivet on the blind side of the hole by pulling on the projecting mandrel. The mandrel is gripped between the jaws of the setting tool and the pressure of grip required depends on a number of factors, including the ductility of the material of the rivet body and the hardness of the material used for the mandrel.

With improved technology, blind rivets are produced from much more difficult materials than hitherto, including mandrels made from very hard materials such for example as stainless steel. With hard material mandrels and less ductile rivet bodies, a much higher grip is required for the jaws of a setting tool if slipping is to be avoided.

It is accordingly one object of the present invention to provide a rivet-setting tool with gripping jaws with a reduced tendency to slip.

A gripping jaw for a rivet-setting tool is usually provided with a row of closely-spaced serrations, ridges or teeth in each of a pair of jaws which are applied symmetrically to the mandrel of a blind rivet. The mandrel is thus gripped by the jaws and pulled into the blind end of the rivet body.

According to the present invention, the jaws of a rivet-setting tool are provided with vari-spaced teeth, that is to say teeth which have non-uniform spacing.

With the spacing of the teeth, the number of teeth in each jaw is reduced and the load on the tool is concentrated on less teeth and thus the load per tooth is increased to give a deeper 'bite'.

The teeth in one jaw may be spaced differently one from another, but located symmetrically in the two jaws of the tool with the teeth in one jaw located directly opposite the teeth in the other jaw. Preferably the arrangement of teeth in the two jaws is staggered so that the teeth in one jaw are opposite a gap in the opposing jaw. In this case, of course, the teeth in each jaw may be equispaced or variably spaced.

In order that the invention be better understood, the invention will now be described in greater detail with reference to the accompanying drawings in which: Figure 1 is a diagrammatic section of a pair of gripping jaws of a conventional rivet-setting tool; Figure 2 is a diagrammatic section of a pair of parallel gripping jaws in a tool according to the invention, and Figure 3 is a diagrammatic section of a pair of staggered gripping jaws of another tool according to the invention.

In Figure 1, pulling teeth 5 are arranged regularly along jaws 6 of a conventional rivet-setting tool, with only tiny gaps 7 between closely-spaced teeth 5.

Figure 2 illustrates a pair of jaws according to the invention in which pulling teeth 5,5' are separated by wider gaps 8 so that the arrangement of teeth in each jaw 6,6' is vari-spaced. The teeth 5 in jaw 6 are located directly opposite teeth 5' in jaw 6' so that the jaws close symmetrically over a rivet mandrel.

The concentration of the load applied to the tool on only a few teeth results in a great improvement of the grip of the jaws on a rivet mandrel and greatly reduces slipping, even when operating with very hard mandrels, such as stainless steel. The increased gap between the teeth also assists the egress of debris such as plating or mandrel material thrown up by the gripping method so that the spaced-tooth jaws of the invention are less prone to fouling during operation.

Figure 3 illustrates an improved tool in which teeth 5 in jaw 6 are located opposite gaps 8' in jaw 6' of the tool and teeth 5' in jaw 6' are located opposite gaps 8 in jaw 6 so that the jaws provide an asymmetric grip on a rivet mandrel.

As in the tool illustrated by Figure 2, the load applied to the tool is concentrated on only a few teeth resulting in a bite which is much less prone to slipping than a conventional rivet-setting tool with closely-spaced teeth. Additionally, there is a tendency to 'bend' or distort the mandrel within the jaw length because the teeth in the opposing jaws are out of register and this further inhibits slipping. The lack of register between opposing teeth reduces still further the retention of debris and the setting tool illustrated by Figure 3 is very much less prone to fouling during operation.

Claims (6)

Claims:

1. Gripping jaws for a rivet-setting tool for mandrel rivets wherein the jaws are provided with vari-spaced teeth.

2. Gripping jaws according to claim 1 wherein the teeth in each jaw have non-uniform spacing.

3. tripping jaws according to claim 2 wherein the teeth are located symmetrically in each jaw so that the teeth in one jaw are directly opposite the teeth in the other jaw.

4. Gripping jaws according to claim 1 wherein the spacing is staggered so that teeth in one jaw are opposite a gap in the opposing jaw.

5. Gripping jaws for a rivet-setting tool substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.

6. A rivet-setting tool for mandrel rivets comprising gripping jaws according to any one of the preceding claims.