GB2505195A

GB2505195A - Joint Configuration

Info

Publication number: GB2505195A
Application number: GB1214878.9A
Authority: GB
Inventors: Darren Johnson
Original assignee: BAE Systems PLC
Current assignee: BAE Systems PLC
Priority date: 2012-08-21
Filing date: 2012-08-21
Publication date: 2014-02-26
Anticipated expiration: 2032-08-21
Also published as: WO2014029973A1; US20150224595A1; AU2013304802A1; AU2013304802B2; EP2888072A1; US10035217B2; GB201214878D0; GB2505195B

Abstract

The invention relates to a joint and welding configuration used during repair of metal and metal alloy plates specifically for providing a means of joining metal plates and filling voids in metal plates where access from one side is restricted. A joint arrangement suitable for repairing a void in at least one element 132 , wherein said at least one element has a first surface and a second surface, wherein the thickness of the at least one element is at least 10mm, further comprising two or more insert elements 336a,336b each of said two or more insert elements each being friction stir welded at their abutted surfaces to said at least one element, characterised wherein said at least one element comprises at least one recess portion, wherein Friction Stir Welding in performed from the direction of said first surface.

Description

Joint configuration The following invention relates to a welded joint configuration used during repair of metal and metal alloy plates specifically for providing a means of joining metal plates and filling voids in metal plates where access from one side is restricted.

Before the present invention is described in further detail, it is to be understood that the invention is not limited to the particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

According to the first aspect of the invention there is provided a joint arrangement suitable for repairing a void in at least one element, wherein said at least one element has a first surface and a second surface, wherein the thickness of the at least one element is at least 10mm, further comprising two or more insert elements, each of said two or more insert elements each being friction stir welded at their abutted surfaces to said at least one element, characterised wherein said at least one element comprises at least one recess portion or shoulder of width of at least 5mm, wherein Friction Stir Welding is performed from the direction of said first surface. This arrangement allows all the welds to be made from a single direction. Therefore it allows repair to an element which has limited access from one side, such as, for example, on the underside of a vehicle vessel or craft, and it removes the need to remove a large amount of equipment from the inside of the vehicle, vessel or craft.

Friction Stir Welding is a method of welding that substantially maintains the physical and mechanical properties of the elements it is applied to. Mechanical and blast tests have shown that Friction Stir Welding of metals and their alloys maintains approximately 90% of the original materials mechanical properties as well as producing welds which have very low detect levels. This is in contrast to other types of welding which are used for joining metal, such as, for example, Metal Inert Gas Welding which uses a tiller material which has a significant impact on the properties and through mechanical and blast testing is known to maintain approximately 60% ot its strength properties. Whilst other forms of welding such as, for example Metal Inert Gas Welding, could be envisaged on the invention, Friction Stir Welding provides the highly preterred joining method.

The improved weld strength properties make Friction Stir Welding suitable tor applications where the structural integrity of the element needs to be maintained to tight tolerances, tor example, armour plating on a vehicle or manufacture ot high pressure vessels, such as, for example fuel tanks and cylinders. Friction Stir Welding can also be used for joining other metals and metal alloys as well as aluminium based composite materials.

The said at least one element and two or more insert elements may be selected trom a metal or metal alloy preferably the metal may be selected from aluminium, titanium, steel or alloys thereof.

The said at least one element comprises at least one recess portion or shoulder ot width ot at least 5mm to enable the Friction Stir Weld tool to access the abutting said at least one element and said two or more insert elements.

Abutting surfaces are two or more insert elements provided to correct tolerances so as to be brought into contact to ensure weld strength.

The thickness of said at least one element is greater than 10 mm as forming recess portions in material less than 10 mm could affect the strength ot the material.

In a further arrangement of the invention, stitching may be added to provide additional strengthening along the length of the joint. Stitching is periodically joining the said at least one element and said two or more insert elements prior to performing the Friction Stir Weld. The stitching may be particularly useful for repairs to thinner elements to minimise any distortion in the at least one element due to the welding process.

In a further arrangement of the invention the abutted surfaces may be arranged at an angle (a) in the range of from 900 to 180° from the second surface ot said at least one element. This allows the joint to be implemented to best satisfy the particular geometry of the repair, or to increase the contact surface area of the abutted surfaces.

In a further arrangement of the invention the abutted surfaces may be non-linear across the plane of the at least one element and at least two or more insert elements, curved or sinusoidal arrangements may be used.

In a further arrangement of the invention the abutted surfaces between said two or more insert elements and/or said recess portion may comprise a plurality of co-locating lugs and voids. This allows locking of the two or more insert elements in place.

In a further arrangement of the invention one or more pins may be inserted between said two or more insert elements or between said two or more insert elements and said at least one element. This allows additional strengthening within the repair.

In a further arrangement of the invention the non-welded surfaces may comprise a layer, such as, for example an adhesive layer, a bonding layer, or a shock attenuating layer. The use of co-locating lugs and voids in combination with a layer provides additional surface area when adhesives and/or shock attenuators are implemented. The use of adhesives or bonding may provide additional strength to the repair.

In a further arrangement of the invention the abutting surfaces may be prepared before welding, such as, for example they may be mechanically and/or chemically cleaned, degreased and/or grit blasted. This promotes improved adhesion between the abutting surfaces and decreases the likelihood of defects in the welds.

In a further aspect of the invention there is provided a method of repairing a void in at least one element comprising a first surface and a second surface wherein the thickness of the element is greater than the depth of a friction stir weld, the method comprising the steps of: I. providing a first insert element such as to furnish an abutting fit in said void, wherein said first insert element has a thickness less than the thickness of said at least one element and the depth which is less than or equal to the depth of said friction stir weld II. friction stir welding the first insert element to the at least one element along the abutted surfaces from the direction of said first surface of said at least one element Ill. forming a recess portion in said at least one element IV. providing a second insert element such as to furnish an abutting fit in said recess portion V. friction stir welding the second insert element to the at least one element along the abutted surfaces, wherein the friction stir welding is performed from the direction of said first surface of the at least one element; Steps Ill, IV and V may be repeated until the requirement of the repair is fulfilled.

In a further aspect of the invention there is provided a vehicle, vessel or craft comprising at least one repaired void according to the invention and method described herein.

In a further aspect of the invention there is provided a joint for repairing a void in at least one element, wherein the thickness of the at least one element is greater than the depth of a friction stir weld joint, comprising two or more insert elements, each of said two or more insert elements each being friction stir welded at their abutted surfaces to said at least one element characterised wherein said at least one element comprises at least one recess portion of width of at least the radius of a friction stir weld tool.

In a further aspect of the invention there is provided a joint suitable for joining two or more elements, wherein the thickness of the two or more elements is greater than the depth of a friction stir weld joint, comprising at least one insert element being friction stir welded at the abutted surfaces to said two or more elements.

An embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings of which:-Figure 1 shows a side view of two elements according to the prior art abutted together and welded.

Figure 2 shows a side view of two elements overlapping each other according to the prior art and welded from both sides.

Figures 3a, 3b and 3c show a cross section of an element containing a void and a number of insert elements welded to the element filling the void.

Figure 4 shows a cross section of an element containing a void and a number of insert elements welded to the element filling the void.

Figure 5 shows a cross section of two elements and an insert element which has been welded to the two elements.

Figure 6 shows a three dimensional view of two elements welded using Friction Stir Welding and an insert element with differing joint configurations.

Turning to Figure 1 (Prior Art), there is provided a first element 2 and a second element 3 abutted together at an abutting surface 5 and welded together by a weld 4 along the entire length, which extends into the page, of the abutting surface 5. If the thicknesses of elements 2, 3 are greater than 25mm then the weld must be carried out from both the top and bottom faces or the weld will not join the entire thickness of the abutted surfaces.

Figure 2 (Prior Art) shows a first element 12 and a second element 13 abutted together with an overlap arrangement 17 which is typically used where elements used are thicker than the depth of a weld. The elements 12, 13 have abutted surfaces isa, 15b and 15c and are welded from both the first surface 11 and from the second surface ha. Clearly if there is restricted access from the first surface 11, then only one weld via the second surface 1 la could be made Figure 3a shows a cross section of an element 132 which may be the floor pan of a tank which has bulging or corrosion 133, which needs to be repaired. The floor pan of the tank has internal workings 130 which prevents repair from inside the vehicle such that repairs can only be made from the exterior, first surface 131. Figure 3b shows a cross section of said element 132 which has been prepared with recess portions or shoulders 233a and 233b larger than the removed portion of damage x. Figure 3c shows a first insert element 336a of length x abutted against element 132, partially filling the void, which is then welded along the entire length of the abutted surfaces 335a and 335b, which extend into the page, by welds 334a and 334b which are made from the direction of the first surface 131. A second insert element 336b is inserted, and located on the recess portions 233a and 233b. The second insert element 336b is welded the entire length of the abutted surfaces 335c and 335d, which extends into the page. The welds 334c and 334d are made from the first surface 131. Optionally there may be a layer 335e such as an adhesive or shock attenuating layer located between the first insert element 336a and second insert element 336b.

Figure 4 shows a cross section of an element 52 as in figure 3. A first insert element 53 is welded in place via welds 54a and 54d which joins element 52 and insert element 53. The surface 60 of insert element 53 is provided with one or more lugs 58 or voids 57, which co-locate with reciprocal voids or lugs on second insert element 56. The abutted surfaces 55b and 55c between the second insert element 56 and element 52 may have non-perpendicular contact surfaces to increase surface area. The element 52 is welded to the insert element 56 along the entire length of the abutted surfaces 55b and 55c, into the page, from the direction of the first surface 51.

Figure 5 shows a cross section of an element 122 and a second element 123 which have to be joined both of which have recess portion 125d and 125e respectively where the insert element 126 is to be located. The elements 122 and 123 are abutted at surface 125a and are welded 124a along their entire length which extends into the page. An insert element 126 fills the recess portion in the elements 122 and 123. The insert element 126 is in contact with the elements 122 and 123 along abutted surfaces 125b, 125c, 125d and 125e and is joined to the elements 122 and 123 by two welds 124b and 124c along the entire length, which extends into the page. The welds 124a, 124b and 124c are all made from the first surface 121.

Figure 6 shows a first element 62 and a second element 63 which are be joined both of which have a recess portion where an insert element 66 is to be located. The elements 62 and 63 are brought together at abutted surface 65a and are welded 64a along their entire length. Insert element 66 is located on elements 62 and 63 and is joined by two welds 64b and 64c along the entire length of the abutted surfaces 65b and 65c. The welds 64a, 64b and 64c are all made from the first surface 61. The join may be enhanced by stitching 67 at intervals along the length of the abutted surfaces. The abutted surfaces may be linear 65c or non-linear 65b, such as sinusoidal or curved as shown.

Claims

Claims 1. A joint arrangement suitable for repairing a void in at least one element, wherein said at least one element has a first surface and a second surface, wherein the thickness of the at least one element is at least 10mm, further comprising two or more insert elements, each of said two or more insert elements each being friction stir welded at their abutted surfaces to said at least one element, characterised wherein said at least one element comprises at least one recess portion, wherein Friction Stir Welding is performed from the direction of said first surface.
2. A joint according to claim 1 wherein said at least one element and said two or more insert elements are selected from a metal or metal alloy.
3. A joint according to any one of the preceding claims wherein the joint further comprises stitching along the length of the friction stir welded joint.
4. A joint according to any one of the preceding claims wherein abutted surfaces are arranged at an angle (a) in the range of from 90° to 1800 from the second surface of said at least one element.
5. A joint according to any one of the preceding claims wherein the abutted surfaces between said two or more insert elements and/or said recess portion of at least one element comprise a plurality of co-locating lugs and voids.
6. Ajoint according to any one of the preceding claims comprising: I. a first insert element which is friction stir welded to said at least one element II. a second insert element located on said first insert element and said recess portion of the at least one element wherein said second insert element is friction stir welded to said at least one element wherein one or more pins are inserted through said second insert element into said at least one element or said first insert element.
7. A joint according to any one of the preceding claims wherein there is a layer between the first and second insert elements.
8. A method of repairing a void in at least one element comprising a first surface and a second surface wherein the thickness of the element is greater than the depth of a friction stir weld, the method comprising the steps of: I. providing a first insert element such as to furnish an abutting fit in said void, wherein said first insert element has a thickness less than the thickness of said at least one element and the depth which is less than or equal to the depth of said friction stir weld II. friction stir welding the first insert element to the at least one element along the abutted surfaces from the direction of said first surface of said at least one element III. forming a recess portion in said at least one element IV. providing a second insert element such as to furnish an abutting fit in said recess portion V. friction stir welding the second insert element to the at least one element along the abutted surfaces, wherein the friction stir welding is performed from the direction of said first surface of the at least one element.
9. A vehicle, vessel or craft comprising at least one repaired void according to any of claims ito 7.
1O.A vehicle, vessel or craft comprising at least one repaired void repaired by a method according to claim 8.
ii.A joint suitable for repairing a void in at least one element, wherein the thickness of the at least one element is greater than the depth of a friction stir weld joint, comprising two or more insert elements, each of said two or more insert elements each being friction stir welded at their abutted surfaces to said at least one element characterised wherein said at least one element comprises at least one recess portion of width of at least the radius of a friction stir weld tool.
12.A joint, method as described herein and with reference to the figures.