AU5504500A

AU5504500A - Improved expansion bolts

Info

Publication number: AU5504500A
Application number: AU55045/00A
Authority: AU
Inventors: Stephen Bakos
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-04-26
Filing date: 2000-09-01
Publication date: 2000-11-02

Description

01/09 '00 FRI 15:19 FAX 61 2 99576288 f GR%]A7FITH HACK 61 2 995762388 [Aj 005

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant: STEPHEN BAKOS Invention Title: IMPROVED EXPANSION BOLTS The following statement is a full description of this invention, including the best method of performing it known to me/us: RECEIVED TIME I. SEP. 15 15 RECEVEDTIM iSE. 1:15PRINT TIME 4. SEP. 7:11

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant: STEPHEN BAKOS Invention Title: IMPROVED EXPANSION BOLTS The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 IMPROVED EXPANSION BOLTS The Technical Field The invention relates to improvements for expansion bolts. More particularly, the invention relates to improvements for expansion bolts in solid structures such as concrete and hebel.

Background Art Expansion bolts are used to secure structures to solid bodies such as walls and floors so as to provide secure attachment for the structure. Typically a hole is first i bored into the solid body, the expansion bolt is placed within the hole and then it is turned a number of times until it expands within the hole and provides secure .attachment for the bolt within the solid body.

*One such expansion bolt is generally known within the art as a DYNA bolt. The DYNA bolt includes a bolt with a o*oo stopping member on a first end of the bolt and a sleeve 20 which is adapted to be slidably moveable along the axis of e° a the bolt, the sleeve is provided with a number of apertures that are longitudinal to the axis of the bolt. In use, the bolt is rotated and imparts an axial force onto the sleeve, :forcing it to expand outward into the solid body.

Another expansion bolt which has been suggested is described in US Patent 5,458,448 (Cheng) which discloses an expansion bolt comprising an elongated bolt body and an expansion cylinder around the bolt body. Disposed between a first end of the stem and the expansion cylinder is an expanding ring which slides over the bolt body, and a nut member which threadingly engages the bolt body so that in use as the bolt is turned in a clockwise direction it forces the expanding ring into contact with the sleeve. As in the DYNA bolt, the sleeve is also provided with a variety of slits longitudinal to the axis of the stem. As the nut is turned, axial force is applied by the nut head S:\39431.doc 3 the expanding ring which forces the slits to open up within the hole as the nut is turned.

A disadvantage with these expanding bolts is that once the expanding bolt has been expanded within the hole the bolt stem cannot be removed as the expanded end portion is integrally formed with the stem. It would therefore be an advantage if at least some of the preferred embodiments of the present invention provided an expanding bolt for insertion into a hole provided in a solid body which, after the expanding bolt has expanded, the stem could be removed from the solid body. This feature would be a particular advantage in situations in which a structure is only needed temporarily to secure a solid body and then to remove the bolt. The hole could then be filled in.

*o o It would be yet another advantage if the invention at least provided an alternative expansion bolt to that which is currently known.

~Summary of the Invention According to a first aspect of the present invention, there is provided a bolt for secure attachment to a solid body, the bolt comprising at least: a stem provided with a first end and a second end, the second end of the stem being adapted to be inserted into the solid body; an expansion means coupled to and located on the stem:, between the first end and the second end, the expansion means incorporating a plurality of fingers located in a first position substantially parallel to the stem, the fingers being adapted to expand from the expansion means into a second position forming barbs oriented to restrain removal of the bolt from the expansion means; and an engaging means axially movable on the stem and located between the first end and the expansion means, wherein in use, when the stem is inserted into a predrilled hole provided in the solid body and an axial force S:\39431.doc 4 is applied to the stem, the expansion means is biased against the engaging means forcing the fingers to expand from the expansion means.

Preferably the stem is provided with a male thread which engages a female thread provided on the expansion means so that as the stem is rotated in a first direction, the engaging means is forced into contact with the fingers of the expansion means, forcing the fingers radially outwardly with respect to the solid body.

Advantageously the engaging means includes a cylindrical sleeve disposed between the first end of the stem and the second end of the stem.

Preferably the plurality of fingers are provided around a circumferential edge of a nut in equilaterally spaced arrangement, parallel to the stem. Typically the fingers are disposed in an inclined position with respect to the stem so that the second end of the sleeve can slide under a distal end of the fingers and provide a wedging force urging the fingers into the solid body.

Typically on the first end of the stem, there is provided a head which can be engaged by a turning tool.

Typically, the turning tool is a hexagonal head bolt or a square head bolt head.

Description of Drawings Figure 1 shows a first embodiment of the invention in cross section before the bolt has been placed inside a hole and expanded; Figure 2 shows the embodiment of Figure 1 in cross section in its expanded form inside a solid body; Figure 3 shows a second embodiment of the invention when the bolt is not expanded; Figure 4 shows the second embodiment of the invention in cross section view when the bolt has expanded; and Figure 5 shows a front view of the bolt when the bolt is expanded.

S:\39431.doc 5 Mode of the Invention Referring to Figure 1, there is shown an expanding bolt 10 in a disengaged position. The bolt incorporates a stem 12 which is provided with a first end 14 and a second end 16. At the first end 14 there is provided a metal washer 18 and a hexagonal bolt head An expansion means in the form of expanding sleeve 22 is coupled to the stem by a female thread 23 provided on the inner surface of expanding sleeve 22. The expanding sleeve is also provided with a plurality of fingers in the S. form of expanding arms The bolt also includes an engaging means in the form of the cylindrical sleeve 26 disposed between the washer 18 and expanding sleeve 22.

In use the bolt 10 is placed within a pre-drilled hole 28 as shown in Figure 2, the bolt head 20 is turned in a clockwise direction by a spanner so as to drive the male thread of the expanding bolt 10 into the female thread of 20 the expanding sleeve 22. As the bolt is rotated in the clockwise direction, the space between the washer 18 and the sleeve 26 gets smaller and smaller until the washer abuts the engaging sleeve. As the bolt is turned further the washer 18, sleeve 26 and expanding sleeve 22 are all in abutting contact with each other. As the bolt is rotated in a clockwise direction an axial force is applied to each engaging surface. Upon further turning the bolt head the sleeve 26 abuts against the expanding sleeve 21 at contact point As can be seen in Figures 1 and 2, the stem as it is kept turning, drives the contact point 30 closer and closer to the second end 16. This axial force ensures that the expanding arms 21 are driven out in an outwards direction by the axial force of the rotating stem into the solid body 32. The bolt is only turned as much as is necessary to effect the expanding arms 25 outwards.

S:\39431.doc 6 Once the sleeve 26 and expanding sleeve 22 abut each other, the stem typically only requires to be rotated two full turns to ensure that the expanding arms 21 extend out from the bolt into the solid body.

In this embodiment, the diameter of the bolt is When the expanding arms 21 are fully expanded to their maximum extent the diameter of one arm to a corresponding opposite arm will give a 25mm anchorage diameter within the solid body 32.

Referring to Figure 3 this shows another embodiment of the invention, in which the expanding sleeve 22 is of a different shape. However it will be appreciated that this embodiment of the invention functions the same as that disclosed in the first embodiment. Referring to figures 4 and 5, it can be seen that the expanding arms 21 expand around the periphery of the bolt and provide good anchorage.

It is an advantage of the invention, that the stem can be removed from the hole 28. For example, if a temporary structure was fixed to a wall, it would be possible to remove the bolt from the wall after use and then fill in the hole with any appropriate filler.

It will be further appreciated by those skilled in the art, that the presence of the barbs 25, is an improvement over the previously known expansion bolts such as the DYNA bolt. As can be seen in Figure 5, the barbs face in a direction to the surface of the solid body so that as a load is applied to the bolt 10, the barbs 25 insert deeper into the solid body 32. In DYNA bolts, is a sufficiently large load is applied to the bolt, the expanded body of the DYNA bolt does not insert deeper into the solid body.

Hence, the present invention provides improved anchorage for the bolt when a load is applied to it.

Referring to Figure 5 it will be seen that the barbs 25 are equilaterally spaced around the periphery of the bolt 10, so providing secure anchorage for the bolt 10. As S:\39431.doc 7 can be seen in Figure 4, the maximum extension of the barbs is such that they are transverse with respect to the axis of the stem 12. Additionally, the female thread provided on the internal periphery of the expanding sleeve 22, enables the bolt 10 to be easily removed from the hole.

In the embodiment of Figures 3, 4 and 5, barbs 25 are equilaterally spaced so that the bolt 10 is anchored within the solid body 32 such that any load applied to the bolt is distributed over the total area that the barbs 25 are in contact with the solid body 32.

Additionally, the barbs 25 can be provided on the expanding sleeve 22 by any form of joining means, such as welding or being formed integrally with the bolt member by a moulding process. Once the barbs 25 have expanded in the solid body as shown in Figure 4 and Figure 5, the bolt stem 12 together with the sleeve 26 is easily removed by turning the bolt head 20 in an anticlockwise direction.

When the bolt 20 and sleeve 26 are removed from the hole 28, the expanding sleeve 22 remains within the solid body. The bolt can then be placed back into the solid hole 28 at any time, and it is not necessary once the barbs have expanded, that the bolt include the cylindrical sleeve 26.

It will be appreciated by those skilled in the art that a plurality of expanding sleeves 22 and cylindrical sleeves 26 can be used on a stem 12 which is7 particularly long. For example, where a deep hole is to be drilled within a foundation and a long bolt is required to anchor into the foundation, more than one expanding sleeve and cylindrical sleeve can be used so that the bolt is anchored substantially along its whole length.

It will be further appreciated that the bolt can be used in a number of types of solid bodies, such as brick, concrete, timber and hebel.

It would be further appreciated by a person skilled in the art that numerous variations and/or modifications may S:\39431.doc -8be made to the present invention as shown in the embodiments without departing from the spirit and the invention as broadly described. The embodiments are, therefore to be considered in all to be illustrative and not restrictive.

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Claims

2. A bolt for secure attachment to a solid body, according to claim i, wherein the stem is provided with a "male thread which engages a female thread provided on the expansion means so that as the stem is. rotated in a first direction, the engaging means is forced into contact with the fingers of the expansion means, forcing the fingers radially outwardly with respect to the solid body.
3. A bolt for secure attachment to a solid body, according to claim 1 or 2, wherein the engaging means includes a cylindrical sleeve disposed between the first end of the stem and the second end of the stem.
4. A bolt for secure attachment to a solid body, according to any one of the preceding claims, wherein the S:\39431.doc 10 plurality of fingers are provided around a circumferential edge of a nut in equilaterally spaced arrangement, parallel to the stem.
5. A bolt for secure attachment to a solid body, according to claim 4, wherein the fingers are disposed in an inclined position with respect to the stem so that the second end of the sleeve can slide under a distal end of the fingers and provide a wedging force urging the fingers into the solid body.
6. A bolt for secure attachment to a solid body, according to any one of the preceding claims, wherein on the first end of the stem, there is provided a head which 15 can be engaged by a turning tool.
7. A bolt for secure attachment to a solid body, substantially as herein described with reference to any one aof the accompan claimng drawings. Dated this 1 st day of September 2000 STEPHEN BAKOS By his Patent Attorneys GRIFFITH HACK GRIFFITH HACK. S:\39431.doc