GB2299639A

GB2299639A - Fastener

Info

Publication number: GB2299639A
Application number: GB9507303A
Authority: GB
Inventors: David Simon Hammond; Paul William Hanratty
Original assignee: Avdel Systems Ltd
Current assignee: Avdel UK Ltd
Priority date: 1995-04-07
Filing date: 1995-04-07
Publication date: 1996-10-09
Anticipated expiration: 2015-04-07
Also published as: GB9507303D0; GB2299639B

Abstract

A stud member for blind installation in panel has generally cylindrical symmetry and comprises a radially enlarged head (13) one end; an externally threaded attachment portion (15) at the other end; a radially expandible portion (17), intermediate the head and the attachment portions; a bore (18), opening at the head end of the body and extending through the radially expandible portion (17); and an internally threaded portion (21) opening from the bore (18) at the end thereof remote from the head; whereby, when the member is inserted through a suitable aperture (24) in a workpiece (23) so that the head (13) contacts one face thereof and the attachment portion (15) and at least part of the radially expandible portion (17) protrude beyond the opposite face thereof, a suitable screw or other threaded member can be threadedly engaged with the internally threaded portion (21) of the member and used to draw that portion of the member towards the head (13) thereby radially expanding at least part of the radially expandible portion (17), so that the member is secured to the workpiece (23) by gripping the latter between the head (13) and the expanded part (28), with the externally threaded attachment portion (15) providing a stud secured to the workpiece (23).

Description

FASTENER MEMBER The invention relates to a fastener member, and more particularly to a fastener member for use as a stud.

In current manufacturing practice under production line conditions, it is advantageous to be able to secure fasteners much as studs to workpieces as rapidly and easily as possible. The present invention is aimed at facilitating this.

The present invention provides, in one of its aspects, a member for use as a stud and having generally cylindrical symmetry, and comprising: a radially enlarged head at or towards one end; an externally grooved attachment portion at or towards the other end; a radially expandible portion, intermediate the head and the attachment portions; a bore, opening at the head end of the body and extending through the radially expandible portion; and an internally threaded portion opening from the bore at the end thereof remote from the head;; whereby, when the member is inserted through a suitable aperture in a workpiece so that the head contacts one face thereof and the attachment portion and at least part of the radially expandible portion protrude beyond the opposite face thereof, a suitable screw or other threaded member can be threadedly engaged with the internally threaded portion of the member and used to draw that portion of the member towards the head thereby radially expanding at least part of the radially expandible portion, so that the member is secured to the workpiece by gripping the latter between the head and the expanded part, with the externally grooved attachment portion providing a stud secured to the workpiece.

The external groove or grooves on the attachment portion may provide a screw thread. Alternatively, the external groove or grooves on the attachment portion provide a fir-tree or other barbed configuration.

Preferably the exterior of the part of the member adjacent the head is of non-circular cross-section, thereby to resist rotation with respect to the workpiece.

A specific enmbodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a longitudinal axial section, on the line I-I of Figure 2, through a stud before placing, also indicating part of a placing tool; Figure 2 is an end elevation of the stud, in the direction of the arrow II of Figure 1; and Figure 3 corresponds to part of Figure 1 and shows the stud after placing.

The stud of this example is made of steel and is of generally cylindrical symmetry about an axis 11. It comprises a member 12, which in this example is about 25mm overall length. It has a radially enlarged flangelike head 13 at one end, and an externally grooved attachment portion 14 at the other end. In this example the external grooving takes the form of a screw-thread 15, which is of M6 size. Alternatively the external grooving could take the form of a fir-tree, or other barbed configuration, which allows rapid attachment thereto. Adjacent the head 13 is a radially expandible portion 16. This comprises a relatively thin wall 17 surrounding an axial bore 18 which opens at the head end of the body. The bore 18 is cylindrical, that is, the interior of the thin wall 17 is cylindrical.However the outside of the thin wall 17 is hexagonal in section, as illustrated in Figure 2, having six flat faces 19. The "across flats" dimension of the hexagon is substantially the same as the crest diameter of the thread 15, as also illustrated in Figure 2.

The stud also comprises an internally threaded portion 21, having an internal screw thread 22 co-axial with the bore 18. The internally threaded portion 21 opens from the inner end of the bore 18 and extends into the inside of the externally grooved portion 14, to a point about half way along the latter. Thus the internally threaded portion 21 and the externally grooved portion 14 overlap each other.

In use, the stud member is placed in (i.e. secured to) a workpiece in the form of a panel 23 (shown in Figure 3) which has a thickness substantially less than the axial length of the radially expandible portion 16 of the stud. The panel is pre-formed with a hexagonal hole 24 (Figure 3) in which the hexagonal exterior of the portion 16 fits. The stud is inserted into and through the hole until the rear face of the head 13 contacts the panel. The attachment portion 14 and a substantial part of the radially expandible portion 16 protrude beyond the panel. Placing is achieved by means of a power tool 25, of which only part is illustrated in Figure 1.

Essentially it comprises a body having at its front end an annular anvil face 26 through which projects a drive screw 27. The tool is equipped with a reversible motor (e.g. electric or pneumatic powered) which can rotate the drive screw 27 in either sense with respect to the tool body and anvil face 26, and retract the drive screw while it is not rotating. A suitable tool is commercially available under the designation AVDEL Series 742. (AVDEL is a Registered Trademark). The tool is offered up to the stud so that the screw 27 enters the bore 18 and contacts the outer end of the screw thread 22. The tool motor is then switched on to rotate the drive screw 27 in the correct sense to screw into the thread, until the tool anvil face 26 contacts the stud head 13.Rotation of the drive screw 27 is stopped, and the drive screw 27 is retracted with respect to the anvil face 26 without rotation. Axial compression is thus applied to the thin wall 17. This causes the part of the thin wall which protrudes beyond the panel 23 to buckle radially outwardly, to form an annular fold 28 (illustrated in Figure 3) which is squeezed hard into contact with the panel. The tool motor is now reversed, to unscrew the drive screw 27 from the stud internal thread 22. This leaves the stud secured to the panel 23, as illustrated in Figure 3. The stud member is secured to the panel by gripping the panel between the head 13 and the radially expanded annular fold 28. The engagement of the hexagonal exterior of the stud with the hexagonal hole in the panel resists rotation of the stud with respect to the panel.

The invention is not restricted to the details of the foregoing example.

For instance, instead of being hexagonal in crosssectional shape, some other suitable non-circular shape could be used, e.g. square, or circular with projecting splines. It would be possible for the member to have a body of circular exterior cross-section, although this would substantially reduce the resistance to turning of the installed stud. For such a member, it would probably be necessary or helpful to use a placing tool with a toothed or serrated anvil face 26, to ensure that the member does not rotate with the drive screw 27 during placing.

The member could be of any convenient size, although it is thought that reducing the exterior thread 15 below about M5 size would mean that the size of the interior thread 22 and consequently of the drive screw 27 would have to be reduced to the point where the drive screw might not be strong enough to support the force required to place the fastener.

The material of the member could be any other suitable material, e.g. stainless steel, aluminium or brass.

It would be possible to use a hand-powered tool to instal a member.

Claims

1. A member for use as a stud and having generally cylindrical symmetry, and comprising: a radially enlarged head at or towards one end; an externally grooved attachment portion at or towards the other end; a radially expandible portion, intermediate the head and the attachment portions; a bore, opening at the head end of the body and extending through the radially expandible portion; and an internally threaded portion opening from the bore at the end thereof remote from the head;; whereby, when the member is inserted through a suitable aperture in a workpiece so that the head contacts one face thereof and the attachment portion and at least part of the radially expandible portion protrude beyond the opposite face thereof, a suitable screw or other threaded member can be threadedly engaged with the internally threaded portion of the member and used to draw that portion of the member towards the head thereby radially expanding at least part of the radially expandible portion, so that the member is secured to the workpiece by gripping the latter between the head and the expanded part, with the externally grooved attachment portion providing a stud secured to the workpiece.

2. A member as claimed in Claim 1, in which the external groove or grooves on the attachment portion provide a screw thread.

3. A member as claimed in Claim 1, in which the external groove or grooves on the attachment portion provide a fir-tree or other barbed configuration.

4. A member as claimed in any of the preceding claims, in which the exterior of the part of the member adjacent the head is of non-circular cross-section, thereby to resist rotation with respect to the workpiece.

5. A member for use as a stud, substantially as hereinbefore described with reference to, and illustrated in, the accompanying drawings.