GB2593676A

GB2593676A - Bonding method

Info

Publication number: GB2593676A
Application number: GB2004293.3A
Authority: GB
Inventors: Dewhirst Mike
Original assignee: Sst Tech Ltd
Current assignee: Sst Tech Ltd
Priority date: 2020-03-25
Filing date: 2020-03-25
Publication date: 2021-10-06
Also published as: GB202004293D0

Abstract

A bonding method for bonding together a first metallic component 16 and a second metallic component 10, 14. The method comprises introducing a deformable metallic component 26 into a recess between the first and second metallic components, where the recess has a neck and a wider securing region, and applying a load to the deformable component 26 so that it deforms and fills the securing region. Preferably both components have a recess. The recess in the second component may be formed during the deformation of the deformable component. The recess provided in the first and/or second component may take the form of a series of serrations. The recesses may be shaped to avoid the presence of sharp corners or angles. The deformable component may be of a tapering form, prior to deformation. A vacuum may be applied to the recess prior to the application of the load. The deformable component may be a low yield strength, high ductility material such as aluminium. A product is also claimed, which is preferably a pressure vessel.

Description

BONDING METHOD

This invention relates to a bonding method for use in forming a bond between metallic material components. It relates, in particular to a method that achieves bonding without requiring heating of the materials to be bonded.

A number of techniques are known for use in bonding or securing metallic material components to one another. By way of example, fasteners such as nuts and bolts or rivets may be used. Whilst the use of such fasteners is appropriate in some circumstances, there are a number of applications in which their use is inappropriate. By way of example, securing together the components forming a high pressure vessel or the like in this manner is unlikely to achieve an appropriately gas or liquid tight connection. Alternative securing techniques include welding or brazing. However, these techniques involve applying high temperatures to parts of the components to be joined, and this may not always be appropriate.

It is an object of the invention to provide a bonding method whereby metallic material components can be secured or joined to one another and in which at least some of the disadvantages associated with known techniques are overcome or are of reduced effect.

According to a first aspect of the invention there is provided a bonding method for bonding together a first metallic component and a second metallic component, the method comprising introducing a deformable metallic component into a recess defined, at least in part, between the first metallic component and the second metallic component, the recess being shaped to define a neck of a first width and a securing region between the neck and a base of the recess, the securing region having a second width, greater than the first width, the deformable component having a width less than or equal to the first width, and applying a load to the deformable component to deform the deformable component in such a manner that a part thereof extends into and across substantially the full width of the securing region.

The securing region may be defined by a recess provided in the first component and a recess defined by the second component. The recess defined by the second component may be formed during the performance of the bonding method by the deformable component deforming the second component into a pocket formed provided in the first component.

The recess provided in the first and/or second component may take the form of a series of serrations. The recess provided in the first and/or second component is preferably shaped to avoid the presence of sharp corners.

The deformable component may be of a tapering form, prior to deformation thereof.

A vacuum may be applied to the recess prior to the application of the load to evacuate a molecules from the voids between the deformable component and the first and second components.

It will be appreciated that through the use of the invention, the first and second components may be secured and bonded to one another, the deformation of the deformable component, and cooperation between the deformable component and the first and second components leading to the formation of a good quality gas or liquid tight seal that is able to withstand the application of high pressure fluids, in use The deformable component is preferably of aluminium. The use of aluminium is advantageous in that it is relatively soft and so may be deformed by the application of relatively low loads thereto. However, the invention is not restricted to the use of aluminium for the deformable component, and other materials of a suitably low yield strength and high ductility may be used.

At least to some extent, the selection of the material for the deformable component may be dependent upon the designs of the first and second components and the materials thereof.

Whilst the description hereinbefore is of an arrangement in which the bonding method allows the formation of a good quality fluid tight bond and so is suitable for use in high pressure applications, the bond achieved using the invention may also be employed in applications in which torques are to be transmitted or axial loadings carried.

The invention further relates to a product manufactured in accordance with the above described method.

The invention will further be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a view illustrating part of a product in accordance with a first embodiment of the invention; Figures 2 and 3 are views illustrating part of the product in greater detail, Figure 2 showing the product part way through the bonding process and Figure 3 illustrating the completed product; and Figures 4 to 6 are views similar to Figures 1 to 3 illustrating and alternative embodiment of the invention.

Referring firstly to Figures 1 to 3, part of a pressure vessel in accordance with a first embodiment of the invention is illustrated. The pressure vessel comprising a generally cylindrical outer skin 10 in the form of a thin walled steel tube, for example of wall thickness in the region of 0.5mm.

At one end, the skin 10 is closed by means of a steel disc 12 that is welded to the skin 10. At its other end, the skin 10 is welded, brazed, bonded or otherwise secured to a steel ring 14 of relatively great wall thickness. As best shown in Figures 2 and 3, the outer surface of the ring 14 is formed with a series of annular grooves or recesses 15 giving the outer surface of the ring 14 a serrated form.

The pressure vessel further comprises a base 16 of copper form. The base 16 includes an upstanding rim 18 of stepped form, shaped to define an abutment surface 20 upon which the ring 14 sits and against which the ring 14 engages, and, at a location radially spaced, outwardly, from the outer surface of the ring 14, an engagement surface 22. The engagement surface 22 is substantially concentric with the outer face of the ring 14 and, like the outer face of the ring 14, is provided with a series of annular grooves or recesses 24, giving the engagement surface 22 a serrated form.

As the base 16 is of copper form, securing the base 16 to the ring 14 by welding to achieve a fluid tight seal therebetween would be inappropriate. In accordance with the invention, therefore, rather than weld or otherwise attach these components to one another in a manner that involves applying heat to the base 16, the base 16 and ring 14 are secured to one another by introducing a deformable component 26 in the form of an annular ring of aluminium into a recess 28 defined between the ring 14 and the base 16, in particular between the outer face of the ring 14 and the engagement surface 22 of the base 16, as shown in Figure 2. The recess 28 defines a neck 30 of a first width, and the presence of the recesses 15, 24 results in the recess 28 defining a securing region 31 of increased second width greater than the first width. A load is the applied to the exposed face of the deformable component 26, squashing the deformable component against the abutment surface 20, and causing the deformable component 26 to deform, expanding its width so as to extend into and substantially fill the recesses 15, 24 defining the securing region 31, as shown in Figure 3. It will be appreciated that, once deformed in this manner, the deformable component 26 is, at least in part, of too great a width to pass through the neck 30 and so is retained within the recess 28 and serves to mechanically secure the ring 14 and the base 16 to one another, and the engagement and cooperation between the deformable component 26 and each of the ring 14 and the base 16 is such that a substantially fluid tight seal is formed between the ring 14 and the base 16.

The manner in which the ring 14 and base 16 are secured to one another achieves the formation of a substantially fluid tight seal, and so is suitable for use in the manufacture of, for example, pressure vessels for use in high pressure applications, without requiring the application of unacceptably or undesirably high temperatures to the components being secured to one another.

Although the recesses 15, 24 illustrated in the accompanying drawings are of V-shaped form, the avoidance of sharp angles or corners is preferred as this may aid achieving complete filling of the recesses 15, 24 with the material of the deformable component 26, in use. By way of example, they may be of generally U-shaped, wave-like form with smooth curves replacing all sharp angles.

The deformable component 26 may be of tapering form, having a reduced width at the end thereof that engages the abutment wall 20, aiding initial deformation and assisting in ensuring that the deformation results in the recesses 15,24 being substantially filled with the material of the deformable component 26, in use.

It will be appreciated that, in the terminology used in the claims appended hereto, the base 16 forms the first component, and the ring 14 forms the second component.

Referring next to Figures 4 to 6, an alternative embodiment of the invention is illustrated. In this embodiment, rather than have a ring 14 welded to the end of the skin 10, the connection is made directly to the skin 10. However, the skin 10 is of insufficient strength to itself be able to withstand the loads arising from the deformation of the deformable component 26. In order to address this, the base 16, instead of defining a rim 18 or stepped form, includes a rim 18 defining an annular recess 32. One wall of the recess 32 serves as the engagement surface 22 and, in this embodiment, is shaped to include a single annular groove or recess 24. The base of the recess 32 serves are the abutment surface 20. The other side wall of the recess 32 serves as a support wall 34 supporting the skin 10. As illustrated, the support wall 34 is provided with an annular groove or recess 15 facing towards the recess 24.

In use, the end of the skin 10 is introduced into the recess 32 and abuts the abutment surface 20, and the deformable component 26 is introduced into the recess 32. It will be appreciated that at this stage in the assembly process, as shown in Figure 5, the skin 10 does not project into the recess 15 formed in the support wall 34. Upon application of the load to the deformable component 26, the deformable component 26 becomes squashed against the abutment surface 20, as described hereinbefore, and undergoes deformation, expanding the width thereof. The deformation of the deformable component 26 causes the deformable component to deform into and substantially fill the recess 24 in the engagement surface 22. It also causes the skin 10 to deform into the recess 15 formed in the support wall 34 until the skin 10 intimately engages the support wall 34, and substantially fills the recess defined by the skin 10 arising from the deformation of the skin 10 into the recess 15 formed in the support wall 34.

It will be appreciated that, in a manner similar to that described hereinbefore in relation to Figures 1 to 3, once deformation of the deformable component 26 is complete as shown in Figure 6, the skin 10 and the base 16 are rigidly, mechanically secured to one another and a substantially fluid tight seal is formed therebetween, suitable for use in high pressure applications such as in the fabrication of high pressure vessels.

It will be appreciated that in this arrangement, in the terminology used in the appended claims, the base 16 forms the first component, and the skin 10 forms the second component.

If desired, in either of the embodiments described hereinbefore, the recess in which the deformable component 26 is located may have a vacuum applied thereto prior to and during the deformation of the deformable component 26, the application of such a vacuum being advantageous in that the presence of molecules of gases present in air between the faces that are to be intimately bonded to one another may be avoided, enhancing the quality of the bonding achieved using the method.

Whilst the description hereinbefore is of the use of an aluminium deformable component 26 in combination with components of steel and copper, it will be appreciated that the invention is not restricted to the use of these materials. The use of aluminium is advantageous in that it is of relatively low yield strength and high ductility, but it will be appreciated that other materials of suitable low yield strength and high ductility may be used, and the selection of the material used in the deformable component may depend, at least to some extent, upon the design and materials used in the components to be secured to one another.

Although the description hereinbefore is of the use of the invention in pressure vessels, it will be appreciated that the invention is not restricted to such applications. The nature of the bond achieved using the method of the invention is suitable for use in load transmitting applications, for example those in which torque loadings need to be transmitted between the first and second components, and so the invention could be applied to drive shafts and the like, if desired. Similarly, it is suitable for use in applications in which axially directed loads are to be carried, and transmitted through the bonded components.

Whilst specific embodiments of the invention have been described herein, it will be understood that a wide range of modifications and alterations may be made to the described embodiments without departing from the scope of the invention as defined by the appended claims.

Claims

CLAIMS: 1. A bonding method for bonding together a first metallic component and a second metallic component, the method comprising introducing a deformable metallic component into a recess defined, at least in part, between the first metallic component and the second metallic component, the recess being shaped to define a neck of a first width and a securing region between the neck and a base of the recess, the securing region having a second width, greater than the first width, the deformable component having a width less than or equal to the first width, and applying a load to the deformable component to deform the deformable component in such a manner that a part thereof extends into and across substantially the full width of the securing region.
2. A method according to Claim 1, wherein the securing region is defined by a recess provided in the first component and a recess defined by the second component.
3. A method according to Claim 2, wherein the recess defined by the second component is formed during the performance of the bonding method by the deformable component deforming the second component into a pocket formed provided in the first component.
4. A method according to any of the preceding claims, wherein the recess provided in the first and/or second component takes the form of a series of serrations.
5. A method according to any of the preceding claims, wherein the recess provided in the first and/or second component is shaped to avoid the presence of sharp corners or angles.
6. A method according to any of the preceding claims, wherein the deformable component is of a tapering form, prior to deformation thereof.
7. A method according to any of the preceding claims, wherein a vacuum is applied to the recess prior to the application of the load.
8. A method according to any of the preceding claims, wherein the deformable component S is of a low yield strength, high ductility material.
9. A method according to any of the preceding claims, wherein the deformable component is of aluminium.
10. A product manufactured in accordance with the above described method.
11. A product according to Claim 10 and comprising a pressure vessel.