GB2424050A

GB2424050A - Expansion fastener having section formed by swaging

Info

Publication number: GB2424050A
Application number: GB0516524A
Authority: GB
Inventors: Gino Di-Mola
Original assignee: ADVANCED BOLTING SOLUTIONS Ltd
Current assignee: ADVANCED BOLTING SOLUTIONS Ltd
Priority date: 2005-08-12
Filing date: 2005-08-12
Publication date: 2006-09-13
Anticipated expiration: 2025-08-12
Also published as: GB2424050B; GB0516524D0

Abstract

A fastener (1) comprises a sleeve with an axial hole (7) therethrough. A lead end (9) of the sleeve is divided into segments (11). A pin (3) radially expands the segments (11) by being driven down the axial hole (7). The axial hole (7) has at least two sections, one of larger diameter (5) extending over most of the sleeve and a smaller diameter section (8) at or near the lead end (9). The smaller diameter section (8) is made by a swaging operation.

Description

TITLE

Swaged fastener

FIELD OF THE INVENTION

The invention relates to fasteners for fastening items together and a method of manufacturing fasteners. In particular but not exclusively, the invention relates to the formation of a swaged area in a slotted sleeve of a fastener and the positioning of that swaged area in relation to the slots of the sleeve of the fastener.

BACKGROUND ART

Rivet bolt type fasteners are known and comprise a cylindrical shaft in which an axial hole has been formed, a smaller diameter section within the axial hole situated in a zone near an end of the cylindrical shaft and an expansion means such as a pin for insertion down the axial hole. The end of the shaft having the smaller diameter section is designated the lead end. Usually the lead end of the cylindrical shaft is axially or otherwise divided into segments that can he expanded radially outwardly by the expansion means. In use, the fastener is placed through holes in aiticles to be joined SO that the lead end protrudes from the far side of the articles. The expansion means is then driven down the axial hole towards the lead end from the head end of the sleeve until it comes into contact with the smaller diameter section. As the expansion means is further driven down the axial hole it exerts a force on the walls of the smaller diameter section, and thus acts as a wedge between the segments driving them apart.

The expanded segments protrude from the far side of the joined articles and act to hold the fastener in place. A nut may also he employed on the head end of the cylindrical shaft to lighten the fastener to the desired torque. The segments arc in the same zone as the smaller diameter section.

The shaft is formed from available stock, which is cut to length. The axial hole is then made in a sequence of steps as described below.

In a first step, a first drill bit is used to partially drill the axial hole into the stock from one end. The hole is not drilled all the way through the stock at this stage; in a second step, the first drill bit is withdrawn at a certain distance from the lead end and a second drill bit of smaller diameter is used to drill the hole all the way through the stock. This results in an axial hole with two different diameters and is the method by which the smaller diameter section is made. In a third step, the first drill bit may be subsequently used to reduce the axial length of the smaller diameter section, by drilling up the axial hole from the lead end so as to widen the already drilled hole. In a fourth step, the sleeve is axially slotted. In an optional fifth step, a threaded portion on the exterior of the sleeve distal to the lead end may be made by rolling. The method of performing these steps can be varied.

Thus it can be seen that the method of making the axial hole comprises several consecutive tooling operations, with most requiring precision drilling. It is an object of this invention to reduce the number of steps used in the manufacture of the axial hole and the smaller diameter section within the axial hole with a consequent saving in time.

SUMMARY OF THE INVENTION

The invention provides a fastener having the features of claim 1.

The sleeve of the fastener is supplied with an existing axial through hole. The axial hole may he of uniform diameter throughout its length. The axial hole may be located centrally within the sleeve so that the axis of the axial hole and the axis of the sleeve coincide. The sleeve itself may be made from cold drawn tubing, and preferably from cold drawn seamless steel tubing.

In order to make the smaller diameter section of the fastener, the sleeve is subjected to a swaging operation. The smaller diameter section is made by swaging the sleeve radially inwardly at a certain distance from one of the ends of the fastener: after swaging this end is designated the lead end. The certain distance is less than half the length of the fastener and may he in the range 0mm to 10mm and is preferably in the range 6mm to 7mm from the lead end. The internal radius of the axial hole may decrease by between 0.7mm to 2mm in the smaller diameter section, and is preferably in the range 0.8mm to 1.3mm, so that a passageway continues through the smaller diameter section. The axial length of the smaller diameter section may be in the range 3mm to 5mm and is preferably around 4mm. It is to he understood that the dimensions and position of the smaller diameter portion can be varied during manufacture according to the intended role of that particular fastener.

The swaging operation may be synchronous with a rolling operation performed on the head end of the sleeve to form a threaded portion.

The sleeve may be subsequently axially slotted at the lead end of the sleeve to divide that end of the sleeve into axial segments. The number of slots may be from two to six Ioi' example and is preferably four. The slots may be equally spaced from each other.

Each slot extends axially over a portion of the sleeve, with the length of each slot being preferably equal or substantially equal to the outer diameter of the sleeve. The smaller diameter section is within the portion of the sleeve containing the slot.

The fastener may be designed and the materials of the fastener chosen so that the fastener meets at least strength grade 8.8.

The fastener may comply with British Standard 3692.

The expansion means may take the form of a pin of substantially the same diameter as the diameter of the larger section of the axial hole. The pin may be advanced down the hole from the head end of the sleeve towards the lead end by applying an axial force to the head end of the pin. Alternatively, the expansion means may be advanced down the axial hole towards the lead end by means of screwing, there being cooperating threaded portions on the expansion means and within the axial hole.

The invention may be used to form the smaller diameter section in the sleeve of three piece expandable fasteners that have integral means for removing the expansion pin from the sleeve of the fastener. Such a fastener may also include means for effecting removal of the fastener from an assembly of joined articles. The fastener includes a hollow sleeve, a pin and a nut. The pin includes a head piece of larger diameter than the sleeve capable of overlapping contact with the nut. The sleeve has two ends, an axially segmented end and a head end distal from the segmented end. A threaded portion is provided on the exterior of the head end for engaging the nut. In use, the sleeve is inserted into a bore running between two or more articles to be joined. The segmented end of the sleeve projects out beyond the end of the bore. The pin is then driven down the interior of the sleeve to expand the segmented end radially outwardly, followed by tightening of the nut. Typically, there is a small gap between the radially expanded segments and a surface of one of the articles around the end of the bore. Tightening the nut draws the sleeve back up the bore and brings the expanded segments into contact with the said surface of the articles, ensuring that the articles are rigidly joined together. if it is desirable to disassemble the joined articles, this is achieved by unscrewing the nut. As the nut is unscrewed, it comes into contact with the head piece of the pin. Further unscrewing lifts the pin partially out of the sleeve, out of contact with the smaller diameter section and thus lets the expanded segmented end relax. This comprises the integral means for removing the pin. The sleeve itself can then be readily removed from the bore by pulling, or by screwing the nut down into contact with a surface of one of the articles around the other end of the bore. Further screwing of the nut against this surface draws the sleeve up into the hole of the joined assembly forcing the segments inwardly. This comprises the means Ibr removing the fastener from the assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a sectional view of the fastener of the invention hefiwe use.

Figure 2 shows a sectional view of the fastener of the invention in use, with the segments expanded radially outwardly.

Figure 3 shows a sectional view of the fastener of the invention in use, when used to join two articles of greater combined thickness than the length of the fastener.

Figure 4 is a sectional view of the sleeve of the fastener with typical dimensions shown.

Figure 5 is an enlarged view of part of the sectional view of Figure 4.

Figure 6 is an axial end view of the lead end of the sleeve.

DETAILED DESCRIPTION

The fastener I shown in Figure 1 includes a pin 3 with a shaft 3a, a head piece 3b and a leading end 3c. The sleeve 2 includes an axial through hole 7 with a smaller diameter section 8 made by swaging and two larger diameter sections 5. The sleeve has a lead end 9. A nut 4 is shown on the sleeve 2 in threaded engagement with a threaded portion 6 of the sleeve. One axial slot 12 is shown at the lead end 9 of the sleeve 2.

Figure 2 shows the fastener I in use, with the segments 11 of the lead end 9 expanded and protruding through the articles 10 to be joined.

Figure 3 shows the fastener 1 in use, with the length of the axially slotted end beyond the narrow diameter section bending towards the axis of the fastener, so that the aistener does not lock prematurely and the pin can he driven fully into the axial hole.

Figures 4 and 5 are of the fastener I with dimensions shown which correspond to the typical values given in Table 1 below. These values are examples only and can he varied provided that the distance of the smaller diameter section from the lead end is maintained as discussed earlier.

Other values which may be used include combinations in the range M8 x 2.5 to M20 x8.0.

With reference to the table below, the M prefix designates that the number immediately following it is the shank diameter, whereas the number Ibilowing the "x" is the thread pitch.

Table 1 (measurements in millimetres) Thread sizes M6x1.OO M8x1.25 MlOxl. 50 M12x1.75 M14x2.OO M16x2.0 M20x2.50 Shank B diameter 6 0 8 0 10 0 12 0 14 0 16 0 20 0 HoleHdiameter 31 41 51 61 71 81 101 Hole 0 diameter 1 50 2 50 3 50 4 50 4 50 5 50 7 50 Holeoffsetfrom end DimM 65 65 65 65 65 65 65 Smaller diameter section Dim N___________________ 40 40 40 40 40 40 40 Slot Length DimS 6 8 10 12 14 16 25 Slot Width Dim W 110 1 30 1 30 1 30 1 60J 1 60 1 80

Claims

1. A fastener comprising; a sleeve with an axial hole therethrough, the axial hole having at least two sections, one of larger diameter and one of smaller diameter, the smaller diameter section being situated at or near the lead end of the sleeve; at least two radial slots starting at the lead end of the sleeve, extending axially along a portion of the sleeve to divide the lead end of the sleeve into segments; and a pin for driving down the axial hole from a head end of the sleeve to expand the segments radially outwardly, characterised in that the smaller diameter section is located within the portion of the sleeve containing the radial slots; the smaller diameter section is made by a swaging operation and the radial slots are made after the swaging operation.

2. A fastener according to claim 1, wherein the smaller diameter section is situated between 0 and 10 mm from the lead end of the sleeve.

3. A fastener according to claim 2, wherein the smaller diameter section is situated between 6 and 7mm from the lead end of the sleeve.

4. A fastener according to claim 1, wherein in the smaller diameter section the radius of the axial hole is decreased by 0.7mm to 2mm compared to the larger diameter section so that a through passageway is maintained through the smaller diameter section.

5. A fastener according to claim I, wherein in the smaller diameter section the radius of the axial hole is decreased by 0.8mm to I.3mm compared to the larger diameter section so that a through passageway is maintained through the smaller diameter section.

6. A fastener according to any previous claim, wherein the length of each axial slot is equal to or substantially equal to the outer diameter of the sleeve.

7. A fastener according to any previous claim, wherein the fastener includes a threaded portion at the head end of the sleeve on the exterior of the sleeve.

8 A fastener according to any previous claim, wherein the [aslener includes a nut in threaded engagement with the threaded portion.

9. A fastener according to any previous claim, wherein the sleeve is made from cold drawn tubing.

10. A fastener according to claim 9, wherein the cold drawn tubing is made from cold drawn seamless steel tubing.

11. A fastener according to any previous claim, wherein the fastener is designed and the materials of the fastener chosen SO that the fastener meets at least strength grade 8.8.

12. A fastener according to any previous claim, wherein the fastener complies with British Standard 3692.

1 3. A method of making the fastener of any of claims 7 to 12, wherein the threaded portion is made by a rolling operation.

14. A method of making the fastener of claim 13, wherein the rolling operation and swaging operation are carried out at the same time.

1 5 A fastener as described herein with reference to the drawings.

15. A fastener as described herein with reference to the drawings. c

Amendments to the claims have been filed as follows:

1. A fastener comprising; a sleeve with an axial hole therethrough, the axial hole having at least S two sections, one of larger diameter and one of smaller diameter, the smaller diameter section being situated at or near a lead end of the sleeve; at least two radial slots starting at the lead end of the sleeve, extending axially along a portion of the sleeve to divide the lead end of the sleeve into segments; and a pin for driving down the axial hole from a head end of the sleeve to expand the segments radially outwardly, characterised in that the smaller diameter section is located within the portion of the sleeve containing the radial slots; the smaller diameter section is made by a swaging operation and the radial slots are made after the swaging operation.

2. A fastener according to claim I, wherein the smaller diameter section is situated between 0 and 10 mm from the lead end of the sleeve.

5. A fastener according to claim I, wherein in the smaller diameter section the radius of the axial hole is decreased by 0.8mm to 1.3mm compared to the larger diameter section so that a through passageway is maintained through the smaller diameter section. (0

8. A fastener according to any previous claim, wherein the fastener includes a nut in threaded engagement with the threaded portion.

1 1. A fastener according to any previous claim, wherein the fastener is designed and the materials of the fastener chosen so that the fastener meets at least strength grade 8.8.

1 2. A fastener according to any previous claim, wherein the fastener complies with British Standard 3692.

13. A method of making the fastener of any of claims 7 to 12, wherein the threaded portion is made by a rolling operation.