GB2317915A

GB2317915A - Improved assembly of a threaded fastener

Info

Publication number: GB2317915A
Application number: GB9618505A
Authority: GB
Inventors: Alastair Vaughan Ramsay
Original assignee: Newfrey LLC
Current assignee: Newfrey LLC
Priority date: 1996-09-05
Filing date: 1996-09-05
Publication date: 1998-04-08
Also published as: GB9618505D0

Abstract

Means are disclosed whereby a secondary component 20 can be secured reliably to a primary component 10, by means of a threaded fastener 2 and a rivet nut 1, for relative movement between the components without one component becoming detached from the other. A head 6 of the threaded fastener passes through a first part 22 of a slot 21. A shank 5 of the threaded fastener can pass from the first part 22 of the slot 21 into an elongate portion 23 of the slot. Restraining means 25,26 prevent the shank from returning to the first part 22 of the slot.

Description

IMPROVED ASSEMBLY OF A THREADED FASTENER The present invention relates to an improved method of assembling and retaining a subassembly to a threaded fastener, and to the means whereby this can be achieved.

It is known to attach a secondary component such as a bracket, cover plate or the like to a primary workpiece by way of a threaded fastener, such as a screw or similar having a thread, passing through the secondary component and secured to the primary component in a bore having a matching thread.

It is often the case that the primary component is in the form of a thin sheet and cannot provide the necessary threaded bore. In such cases rivet nuts are used to provide a preformed bore in the primary component. It will be understood that the forming of such bores is time consuming.

An improvement is known from EP 0 494 747, in which a blind rivet nut with a pulling mandrel, having a flanged rivet tube with an internal thread has the pulling mandrel in the form of a cap screw, the cap being used to engage a setting tool. In the use of this improvement, it is convenient to place a hole in the bracket or cover plate over the cap of the cap screw and to engage the threaded portion of the screw with an elongated slot extending from the enlarged hole. The assembly may then be secured by tightening the screw.

However, it is not always convenient or desirable to have a tight assembly. Indeed, sometimes one component may be required to slide against the other, the screw being necessary to prevent the components parting. In such cases, moreover, there is a risk that the secondary component can move too far, the cap of the cap screw entering the enlarged hole and the components becoming separated.

The present invention has as an advantage that it substantially reduces this risk.

According to the present invention, a secondary component is provided, having a slot formed therein comprising a first portion and an elongated portion extending therefrom, characterised in that restraining means are provided between the first portion and the elongated portion of the slot to allow passage of a member extending through the secondary component slot only from the first portion to the elongated portion.

Preferably the member is a screw and the first portion is an enlarged portion for passing over the head of the screw.

Preferably the retaining means is a biased bar. The member will move from the first portion to the elongated portion of the hole deflecting the bar, once the member is past the bar the bar returns to its original position.

Preferably the slot is provided with a stop against which the bar may rest.

The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a known threaded fastener; Figure 2 shows the fastener of Figure 1 installed in a primary component, the primary section being shown in part-section; and Figure 3 shows a secondary component according to the invention.

Referring to Figure 1 there is shown a rivet nut 1 and a cap screw 2. The rivet nut 1 comprises a body portion 3 a flange 4 and a bore extending into the body portion, a part of which (not shown) is provided with a threaded portion. The cap screw 2 comprises a threaded shank 5 and a cap or head portion 6. The threaded shank 5 is in engagement with the threaded portion of the rivet nut body.

In use, the rivet nut body is inserted into a hole in a primary component 10, such that an underside of the flange 4 abuts the primary component. A setting tool (not shown) holds the rivet nut in place and causes the screw to move relative to the flange. The relative movement of the screw and flange causes the rivet body to buckle and deform on the blind side of the primary component, that is the side of the primary component opposite the side against which the flange of the rivet nut abuts. The primary component is thus secured between the deformed portion 7 of the rivet nut and the flange 4 (Figure 2).

The secondary component 20 may now be secured to the rivet nut assembly. The secondary component is provided with a slot 21 formed therein. The slot 21 comprises a first portion 22 through which the cap of the cap screw may pass and an elongate portion 23. The elongate portion is sufficiently wide to allow free movement of the shank 5 of the cap screw, but sufficiently narrow to prevent the cap 6 of the cap screw from passing through.

The two parts of the slot 21 are separated by retaining means in the form of a biased flexible bar 25 (shown in a rest position in Figure 3). The bar 25 is joined at a first end to the secondary component and is provided at the other end with a finger 26. The finger is adapted to abut a stop 27 formed on the opposite side of the slot from the first end of the bar. The bar 25 is sufficiently flexible to allow the passage of the screw shank from the first portion 22 into the elongate portion 23, and sufficiently rigid to prevent the return of the screw shank from the elongate portion 23 to the first portion 22, during the working life of the assembly.

The bar 25 is also biased to return to its rest position once the screw shank has initially pushed it aside to enter the elongate portion of the slot 21.

The slot 21 may be formed into the secondary component by any means suitable to the material from which the secondary component is formed. For example, for a metallic secondary component, the slot (and the bar formed thereby) may be cut, for example, by laser, or stamped from the secondary component.

Claims

1 A secondary component having a slot formed therein, comprising a first portion and an elongate portion extending therefrom, in which restraining means are provided between the first portion and the elongate portion to allow passage of a member extending through the secondary component only from the first portion to the elongate portion.

2 A secondary component according to claim 1, in which the first portion is enlarged to pass over a head of the member.

3 A secondary component according to claim 1 or claim 2, in which the restraining means is a flexible biased bar.

4 A secondary component according to any preceding claim, in which the slot is provided with a stop against which the restraining means may rest.

5 A secondary component substantially as described herein with reference to and as illustrated in Figure 3 of the accompanying drawings.

6 An assembly substantially as described herein with reference to and as illustrated in the accompanying drawings.