GB2094436A - Sealing bores or other openings - Google Patents

Abstract

A method of sealing a bore 2 in a body 1 by forcing into the bore 2 a closure member 4 which is of such dimensions and shape relative to the dimensions and shape of the bore 2 that 'hoop tension' conditions are produced at the leading and trailing regions of the zone of contact between the member 4 and the bore 2 whereby even though the member has been forced lengthwise of the bore the material of the bore at the trailing region of the member closes in to its original diameter to hold the closure member in place. If desired the wall of the bore 2 can be swaged over to augment the 'hoop tension' effect, <IMAGE>

Description

SPECIFICATION Sealing bores or other openings Background of the Invention This invention relates to methods and arrangements for sealing bores or other openings.

In particular, the present invention is concerned with the sealing of fluids within a bore formed in a metallic element such as a rod, tube or the like.

A particular application of the present invention is to be able to seal bores without involving the use of especially provided screw threaded regions for receiving a screw threaded closure means.

Summary of the Invention According to the invention there is provided a method of sealing a bore or otherwise closing an opening in a wall of a container or other object or an end of a bore in an element or the end of a tubular member; the method comprising the step of forcing into the bore, end or opening a closure member of such shape and size relative to the bore, end or opening that hoop tension forces are produced in the region of contact between the closure member and the adjacent wall surface of the bore, end or opening, which hoop tension forces serve to retain the closure member in place.

Brief Description of the Drawings For a better understanding of the invention and to show how to carry the same into effect reference will now be made to the accompanying drawings in which:~ Figure 1 is a schematic cross-sectional representation of an early stage in the closure of a bore in a thick walled member using the method of the invention; Figure 2 is a view similar to that of Figure 1, but illustrating a second stage in the closure of the bore; Figure 3 is a view similar to Figures 1 and 2 but illustrating the final stage in the closure of the bore and Figure 4 is a cross sectional view of the application of the method of the invention to the closure of the bore, or opening in which a prereduction of bore size is involved before applying the method of the invention.

Description of the Preferred Embodiments Referring now to Figure 1, a body 1 with a bore 2 is required to be sealed so as to retain a liquid or fluid schematically represented at 3 within the bore.

In practice, the body can be an elongate metallic member such as a bolt which is required to exhibit predetermined structural characteristics.

It will be appreciated that in the case of such a bolt it is likely to be externally threaded to receive a retaining nut or the like at the location at which it is desired to close the bore so that it is not readily convenient or possible to utilise a closure member connecting with the external threaded portion.

Alternatively, the body 1 can be part of the member which closes off a liquid or fluid containing chamber under conditions in which it is not desired to utilise a closure member which in any way protrudes or otherwise projects from the adjacent surface of the chamber.

In accordance with the invention a spherical or other suitably shaped member 4 having a cross section greater than that of the bore 2 is forced or pressed into the bore to be held therein by the forces thus created.

Turning now particularly to the Figure 1 this illustrates a stage in which the member 4 has been pressed into the bore to an extent that the member 4 is located below the level of the adjacent surface 5 of the mouth 6 of the bore 2.

During the pressing-in of the member 4 the material of the body 1 in the immediate vicinity of the body 1 is believed to undergo a localised combined elastic and plastic deformation so that during the advance of the member 4 into the bore this localised effect effectively moves along with the member 4.

In practice, the diameter of the member 4 with respect to the diameter of the wall 7 of the bore 2 is such that following the pressing-in of the member 4 to a desired depth or position in the bore 2 a force condition termed 'hoop tension' is developed in the body 1 at both the leading and trailing zones 8 and 9 respectively of the member 4 as seen in the axial direction of the bore 2. This 'hoop tension' is such that at the trailing zone 8 the forces induced in the body 1 are such that the diameter of the bore changes to a value less than that of the member 4 even though the bore wall 7 has previously been stretched or otherwise distorted to allow passage of the member 4.

In addition, the stresses and strains induced in the body at the leading zone 9 are such as to prevent movement of the member 4 further into the bore 2.

It will be understood that the region of contact between the member 4 and the bore wall 7 is greater than a purely line contact and extends over the surface area of a central slice of the member 4.

The consequence of the extended area contact in conjunction with the 'hoop tensions' is to produce a very firm fitting between the member 4 and the wall 7 of the bore 2.

To augment the 'hoop tension' effects the material of the bore in the vicinity of the mouth of the bore can be swaged over so as to overly the trailing zone of the member 4. This swaging stage is shown in Figure 2 in which it will be noted that the material 10 of the body 1 in the vicinity of the mouth 6 of the bore 2 is swaged inwards as indicated. This operation can be effected by any conventient swaging tool (not shown).

Figure 3 schematically illustrates the final stages of such swaging operation in which the outer surface 5 in the vicinity of the bore mouth 6 has been so deformed as to provide a smooth outer surface at the regions 11 adjacent the member 4.

In practice, it has been found that the diameter of the member 4 can be greater than that of the bore 2 within a percentage range of 8~12% with the preferred value being 10%.

The spherical closure member 4 can comprise a precision ground ball commonly known as a ball bearing. Such ball bearing are produced in a wide variety of sizes to very close tolerances of dimensions and with a very smooth surface finish.

Also such balls are of such characteristics as to be highly resistant to crushing forces.

In other words the diameter of the balls used can be used as a means for defining acceptable sizes for the diameters of the bores to be sealed.

In situations in which the bore diameter is greater than the diameter of the closure member it is desirable to use for a particular installation the bore 2 can be effectively reduced in diameter by means of a bush 12. Such bush 12 can be fitted into the oversize bore by any convenient means such as, for example, by soldering, welding, brazing or the like. Following the fitting of the bush, the spherical member 4 is fitted in the manner previously described.

Figure 4 schematically illustrates the use of the bush for the purposes of closing-off a larger diameter bore. It will be understood that in this particular arrangement the original opening need not be of a circular cross section since the outer surface, that is external, shape of the bush can correspond to the shape of the opening into which the bush is to be fitted. The bush will, of course, have a central bore 13 which is cylindrical for the reception of the spherial member 4.

It will be clear that the material of the bush must be such as to enable the production of the above mentioned 'hoop tension' effects which form part of the forces for retaining the closure member 4 in place. In this connection it will be clear that the length of the bush must be sufficient for the member 4 to be wholly located within the axial length of the bush 12.

From the above it will be apparent that the method of the invention provides a means of sealing a bore which avoids the introduction of stress concentrations such as would be caused by the use of a threaded cap, plug or the like. Also the method of the invention makes it possible to seal bores in roads, tubes, or the like which in use are subject to tension forces, vibrations etc., which tend to work loose such threaded closure arrangements.Consequently, the sealing processes of the invention are particularly suitable for sealing fluids into containers, tubes, bores or the like provided in rods or other members which, is use, are subjected to high stresses, shock forces, vibrations in orientations relative to the axial direction of the bore into which the closure member has been introduced or other situations tending to loosen screwed fitments whilst at the same time avoiding time consuming machining operations involved in machining internal and external screw threads or the like.

As has been mentioned, following the pressingin of the closure member 4 the material of the body 1 can be swaged over so as effectively to close off the bore 2 to the rear or trailing side of the closure member 4 This swaging operation can be effected by a peigning operation.

If desired the swaging over operation need not necessarily extend around the whole perimeter of the bore 2 but can be restricted to predetermined regions of the perimeter. It will be understood that whether or not swaging is effected will be a matter of design according to the intended use of the body, element or the like to which the method of the invention is applied.

Whilst the particular form of closure element disclosed has been a spherical ball other shapes could be used provided that the shape provides a circular cross section in one plane which is greater than that of the bore into which it is to fit.

Conveniently, the members would be solids of revolution having a circular cross section in one plane and an oval or elliptical cross-section in planes transverse thereto. It will be appreciated that the shape chosen must be capable of producing the 'hoop tension' effect.

Claims (9)

1. A method of sealing a bore or otherwise closing an opening in a wall of a container or other object or an end of a bore in an element or the end of a tubular member; the method comprising the step of forcing into the bore, end or opening a closure member of such shape and size relative to the bore, end or opening that hoop tension forces are produced in the region of contact between the closure member and the adjacent wall surface of the bore, end or opening, which hoop tension forces serve to retain the closure member in place.

2. A method as claimed in claim 1, in which the end of the bore to the trailing side of the forced-in closure member is at least partially deformed so as to overly the closure member so as to augment the sealing-in of the closure member.

3. A method as claimed in claim 2, in which the deforming is effected by a swaging operation.

4. A method as claimed in claim 1, and including the step of reducing the cross sectional area of the bore before introducing the closure member.

5. A method as claimed in claim 4, in which the cross sectional area is reduced by inserting a bush or sleeve into the bore.

6. A method as claimed in claim 1, in which the closure member is a spherical ball.

7. A method as claimed in claim 6, in which the ball is formed by a ball bearing.

8. A method of sealing a bore or otherwise closing an opening in a wall of a container or other object or an end of a bore in an element or the end of a tubular member, substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 3 and Figure 4 of the accompanying drawings.

9. An element having a bore sealed by the method as claimed in any one of the preceding claims.