GB2536661A

GB2536661A - Weldable elements, joints and associated methods

Info

Publication number: GB2536661A
Application number: GB1504988.5A
Authority: GB
Inventors: R Widger Ian
Original assignee: EVEREST Ltd
Current assignee: EVEREST Ltd
Priority date: 2015-03-24
Filing date: 2015-03-24
Publication date: 2016-09-28
Also published as: GB201504988D0

Abstract

The weldable element 200 comprises an outer section 20 having outermost and innermost surfaces 22, 26 and an abutment face, and a core section 28 having a weld face 218, wherein the innermost surface defines a space 212, the core section being arranged at least partially in the space such that the weld face protrudes beyond the abutment face to provide a sacrificial weld portion. The core may comprise one or more bridging elements 210 to bridge a spacing gap between the core and outer section. The core may be integral to the outer section, or may be a separate component comprising an insert portion and attachment means. The outer section may be prismatic and define a closed loop. The weldable element may be plastic. Also claimed is a joint comprising two weldable elements and a method of constructing the joint. The method comprises heating the weld faces of two elements, contacting the elements against one another and applying a force to them to compress the weld portions and form a weld bead.

Description

WELDABLE ELEMENTS, JOINTS AND ASSOCIATED METHODS The present invention relates to improvements in the construction of window, door, or sash frames, associated apparatus and methods, and particularly but not exclusively to methods and apparatus for welding profiled elements formed of plastic material to form a window, door, or sash frame.

Frames for doors, windows or sashes, and methods of welding plastic to form said frames are well known in the art and PVCu is a commonly used frame material. It is of primary importance when manufacturing such frames to consider both the security and safety of the frame during normal operation.

It should be understood that when a window, door or sash is referred to in this application, the same principles and description will apply to any of a window, door, or sash or frame thereof.

A known method of PVCu frame assembly is hot plate welding. Components to be welded are loaded into holding fixtures and the surfaces to be welded are made clean, flat and free from distortion. The welding cycle is then initiated by positioning a hot plate between the two surfaces to be welded. The welding then takes place in two phases. The first phase comprises pushing the components against the hot plate such that, under the axial load, melting of the surface in contact with the hot plate occurs. When melting occurs, a small continuous bead of molten material forms around the perimeter of the abutting surfaces of the component. This is commonly referred to as sprue. Once the entire joint surface of the component has melted, the axial load is reduced. The reduction can be achieved, for example, by reducing the pneumatic pressure in the system, or by using melt depth stops. Melt depth stops are commonly positioned on the welding machine, between the hot plate. The machine slides to give a predetermined melt depth.

Upon reduction of the axial load, the second phase of the welding cycle begins wherein the hotplate is removed from between the two surfaces of the components to be welded and the components are brought together and allowed to cool under axial load for the joining phase. Melt depth stops can be used to control the amount of material displacement during the joining phase and when the joining phase is complete, the welded components are removed from the holding fixtures.

The weld bead, or sprue, forms on both sides of the component. Therefore, the bead is visible on an external surface of the weld about its entire perimeter. In many applications, it is not desirable to have a weld bead on the external surface of the component. A weld bead on the external surface can change the profile or shape of the component and therefore make it unsuitable for use in certain locations, or, more commonly, reduces the aesthetic appearance of the components which are welded.

The weld bead can be removed by a secondary operation, such as by hand or using a machining tool. However, secondary operations increase the cost and time for producing a finished weld. Furthermore, even after the weld bead is removed, the weld can still be unsightly. Therefore a third operation to pen in or cover the weld is optionally performed, adding further to the expense and duration of the welding operation.

It is an object of the present invention to provide a system which alleviates some or all of the issues with prior art welding for PVCu window frame elements, and in particular improves the aesthetics of a welded joint without the requirement to perform further operations following welding.

STATEMENT OF INVENTION

In a first aspect, the present invention provides a weldable element comprising an outer section having a substantially continuous outermost surface, a substantially continuous innermost surface, and an abutment face; a core section having a weld face, wherein the innermost surface defines a space; and wherein the core section is arranged at least partially in said space and such that the weld face protrudes beyond the abutment face by a predetermined distance to thereby provide a sacrificial weld section.

When welding two elements together, a weld bead is formed which typically expands in a perpendicular direction from the force applied to the elements towards each other. Therefore, the weld bead can often protrude from the surface of the elements being welded. This external weld bead does not provide a smooth transition between the welded components after welding. In applications where the aesthetic aspect of the product is particularly valuable, this weld bead may be detrimental to the aesthetics of a product when welding is part of the product assembly process.

Providing a weld face partially within the internal space of the outer section of a weldable element provides that significant extra space is provided, into which the weld bead can expand without spilling outside the outermost surface of the outer section. Therefore, the weld bead does not protrude from the outer section after welding and the aesthetics of the welded joint are significantly improved.

Furthermore, as the weld face protrudes from the abutment face of the weldable element, a hot plate can be applied to the weld face without the abutment face being heated. Therefore, the clean smooth outer surface of the element can abut with a similarly clean smooth outer surface of another weldable element and provide a substantially smooth transition between the two elements. If the outer section or the abutment face were to be heated, then a weld bead would form between the two abutment faces of two elements when coming into abutment.

The predetermined distance may be any distance required, but in preferable embodiments, may be in the range of 0-50mm, 1-20mm, 1-8mm, 1-6mm or most preferably 1-5mm. In particular preferable embodiments, the predetermined distance may be 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 10mm, or 20mm.

Preferably, the outer section and the core section may be formed as integral parts. Therefore, no assembly operation is required to locate the core section within the outer section, reducing labour and manufacturing costs.

Advantageously, a spacing gap may be provided between the innermost surface and the core section. A spacing gap provides further space into which the weld bead can expand without interfering with the abutment of the abutment faces of two elements being welded.

The size of the spacing gap can be preselected such that the weld bead is formed entirely within the spacing gap or within the spacing gap and partially adjacent the abutment face. Therefore, the spacing gap could prevent any of the weld bead from projecting out of the outermost surface of the outer section, thereby improving the aesthetics of the welded joint.

The element may comprise a well, trough, or gap located in the space defined by the innermost surface, which receives and contains and bead formed by a welding operation.

Preferably, the core section may comprise one or more bridging elements that space the core section from the innermost surface of the outer section to thereby provide the spacing gap. The bridging elements can provide increased structural integrity to the weldable element as a whole, and the length of the bridging elements can be tailored easily during manufacture to provide the desired size of the spacing gap.

Preferably, a portion of the outer section is removed by a removal operation to form the abutment face. Therefore, the abutment face can be formed in a desired manner depending upon the required characteristics of the weldable element or the weld.

More preferably, the removal operation forms the abutment face at a predetermined distance from the weld face to thereby form the sacrificial weld portion. Therefore, the outer section and core section can be initially manufactured at the same length, which facilitates an extrusion manufacturing technique. An extruded length of outer section and core section can then be cut to a desired length. A removal operation performed upon the end of the outer section may then form the abutment face set back from the weld face such that the sacrificial weld portion of the core section protrudes from the abutment face. The abutment face may be in the form of a rebate or shoulder on the element.

Alternatively, the core section may be provided as a separate component to the outer section. A separate core section can be installed after production of the outer section, thereby simplifying the construction of the outer section. Furthermore, a single core section could be utilised for a variety of different types of outer section to create a range of different weldable elements.

A separate core section can be easily manufactured from a different material to the outer section, and therefore the core and outer sections can be better tailored to their specific purposes. For example, the core section can be manufactured from a material that exhibits preferential welding properties to the detriment of its aesthetics, while the outer section's material can be selected to be more hardwearing and aesthetically pleasing, while its welding properties are less important. Furthermore, the materials of the outer and core sections can be chosen to provide increased strength or rigidity to the weldable element.

The core section may comprise an insert portion for insertion into the internal space and a weld portion comprising the weld face and the sacrificial weld section. Therefore, the core section can be designed to provide tailored operation for the insert and weld portions respectively. The insert section can be designed with improved properties for securing within the internal space, as it is not to be welded, and the weld section can be tailored to suit the welding operation.

Preferably, the insert portion comprises attachment means to attach the core section to the outer section. Therefore, the core section can be securely attached to the outer section to ensure a strong and effective connection between two weldable elements after a welding operation, despite only the weld sections of each respective element being connected to one another. The attachment means may comprises an interference fit with the outer section, a mechanical connection, or an adhesive, amongst other options. Any means for attaching two components to one another can be used as the attachment means. In preferable embodiments, the attachment means may be screws, bolts, hooks, nails, adhesive, lockable nuts, twist-locking components, complementary engagement components, threaded components interference fits, welding, friction welding, or snap-fitting.

The insert portion of the core section may comprise one or more heat conducting elements which can conduct heat from the weld face to thereby melt a portion of the core section distant from the weld face. The heat conducting elements may form the attachment means. The heat conducting elements may be arranged such that, in use, the heat conducting elements come into contact with the outer section.

The portion of the core section distant from the weld face may be the insert portion of the core section. Therefore, when a weld plate is pressed against the weld face, heat from the weld plate can melt, or partially melt, the insert portion of the core section. This melting of the insert portion, once solidified, can aid in retaining the insert portion within the outer section. Preferably, the heat conducting elements are metallic elements.

Alternatively or additionally, the heat conducting elements may form the attachment means The heat conducting elements may be arranged such that, in use, the heat conducting elements come into contact with the outer section or webs within the outer section.

Therefore, when a weld plate is pressed against the weld face, the weld plate can heat the heat conducting elements, which will then easily penetrate the material of the outer section or webs therein to thereby attach the core section to the outer section and retain the insert portion within the outer section more securely.

Preferably, the weld portion may comprise one or more of a flat plate of weldable material, a profiled plate of weldable material, or a frame of weldable material. Therefore, the area of contact between the weld face of each element to be welded can be maximised or optimised. A profiled plate of weldable material can include a grooved, ribbed, dotted, corrugated or any other non-smooth profile. A frame of weldable material can be made from spars or internal webs of weldable material, or any other shape. The frame or plate of weldable material can be made symmetrical or rotationally symmetrical such that two weldable material frames or plates can have a maximum area of contact regardless of their orientation.

The core section may be located entirely within the internal space. Therefore, the entire weld face can be located within the internal space to prevent the weld bead from extending outside the outermost surface.

The weldable element may be an elongate weldable element having a length. An elongate element has one of its dimensions substantially larger than its other two dimensions. Preferably, the length may be 2, 3, 5, 8, or 10 times larger than the width or height of the element.

The outer section may be formed of a shaped section which is repeated along the length of the weldable element. Therefore, an extended length of outer section can be manufactured and cut into pre-selected shorter outer sections dependent upon the size of the weldable element required.

Alternatively, the outer section may be substantially prismatic. Similarly, to a repeated shaped section described above, a smaller weldable element can be manufactured from an extended length of outer section which has been cut to a pre-determined length. A substantially prismatic outer section need not be entirely prismatic.

A substantially prismatic or repeated shape outer section may have a substantially continuous shape or repeated shape pattern along its length such that an extended length of outer section can be cut into a plurality of substantially identical shorter lengths of outer section.

The weldable element may comprise a first end. The abutment face and the weld face may be located proximal the first end to thereby form the sacrificial weld section.

Alternatively, the core section may extend within the internal space along substantially all of the length of the weldable element. A core section which extends within the internal space can be securely located within the outer section.

Preferably, the weldable element comprises a second end, and wherein a second abutment face and a second weld face are located proximal the second end to thereby form a second sacrificial weld section. Therefore, a similar welding operation can be performed at both ends of a weldable element to form complex structures and frames.

Furthermore, a core section which extends within the internal space along substantially all of the length of the weldable element can have a first and second end. The weld face can be formed at a first end of the core section and the second weld face can be formed at the second end of the core section such that a single core section is required to form a welded joint at both ends of the weldable element.

Alternatively, a second core section may be arranged at least partially within the internal space such that the second weld face protrudes from the second abutment face by a predetermined distance to thereby provide the second sacrificial weld-able section. If two core sections are utilised, then there is not wastage of core section material throughout the length of the weldable element where it is not required.

Preferably, the core section may be constrained within the internal space such that it may move only along an axis of the length of the weldable element. Therefore, the core section can fit tightly within the outer section such that it is immobile in perpendicular directions, but can be inserted easily when fed into the internal space linearly along the outer sections long axis.

Further preferably, the core section may be shaped such that an outer surface of the core section is in contact with substantially all of the innermost surface of the outer section. Therefore, the core section is constrained such that it can be moved relative to the outer section along the length axis of the outer section.

Preferably, the weldable element is a plastic element. More preferably, the weldable element is a window, door, or sash frame element.

In a second aspect, the present invention provides a joint comprising a first weldable element according to a first aspect of the invention and a second weldable element according to a first aspect of the invention.

Preferably, in the joint, the weld face of the first weldable element is welded to the weld face of the second weldable element such that the abutment faces of the first and second weldable elements are located in abutment with one another. Therefore, there is provided a smooth transition between the outer section of the first and second weldable elements such that the aesthetics of the joint are improved.

Preferably, the joint is a window, door, or sash frame joint. Aesthetics are a key consideration when constructing an externally or internally facing window, door, or sash frame joint.

In a third aspect, the invention provides a method of constructing a joint according to a second aspect of the invention, wherein the method comprises the steps of heating the weld faces of at least one of, and preferably both of, the first and second weldable elements; contacting the weld faces of the first and second weldable elements against one another; and applying a force to the weldable elements to thereby maintain the weld faces of the first and second elements in reciprocal contact and compress the sacrificial weld portions of the first and second weldable elements to thereby form a weld bead.

Preferably, the weld bead is formed entirely within a volume defined by the outermost surfaces of the first and second weldable elements. Therefore, the weld bead does not protrude from the outer sections and provides a more aesthetically pleasing a smooth joint between the two weldable elements.

Alternatively, the weld bead may be formed at least partially between the abutment surfaces of the first and second weldable elements. Therefore, a physical connection can be made between the outer sections of the two weldable elements without the requirement to melt or heat the outer sections. As the weld bead is initially in a melted state when it forms, the molten bead can be compressed between the two abutment faces to form a seal and connection between the two abutment faces.

If one or both of the weldable elements comprise a spacing gap as described above, then the weld bead may advantageously be formed within the spacing gap. Therefore, the abutment faces will not come into contact with the weld bead and can come into close contact, thereby providing a near-seamless transition between the two outer sections. In particular, where the outer section is designed with a realistic pattern, such as a wood or metallic effect, then a seamless transition is desirable, as any visible weld will remove the illusion that the outer section is made from wood or metal (i.e. it will be obvious that the joint is made from plastic).

Preferably, the method is a method of constructing a window, door, or sash frame joint.

It will be understood by the skilled person that these preferable and advantageous features may be combined with one another and that any resulting embodiments will also be embodiments of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

A better understanding of the present invention wifi be n ned from the following detailed description. The description is given by way of example only and makes reference to the accompanying drawings, in which: Figure 1 is a cross-sectional or end view of a prior art weldable window, door, or sash frame element; Figure 2 shows a cross-sectional or end view of a weldable window, door, or sash frame element according to the present invention; Figures 3a-d show end and side views of a weldable window, door, or sash frame element according to the present invention during preparation for welding; Figure 4 illustrates a perspective view of a weldable window, door, or sash frame element according to the present invention after preparation for welding; Figures 5a-c shows an assembly operation of a joint comprising two weldable window, door, or sash frame elements according to the present invention; Figures 6a-c shows an assembly operation of a joint comprising three weldable window, door, or sash frame elements according to the present invention; Figure 7a shows a perspective view of an alternative outer section of a weldable window, door, or sash frame element according to the present invention; Figure 7b shows a cross-sectional or end view of an alternative core section of a weldable window, door, or sash frame element according to the present invention Figure 7c shows a cross-sectional view of an alternative weldable window, door, or sash frame element according to the present invention; and Figures 8a-d show various alternative core sections of weldable window, door, or sash frame elements according to the present invention.

Figure 1 shows a cross sectional view of a prior art weldable window, door, or sash frame element 100. For the purposes of this detailed description, the element will be referred to in relation to a window, but it should be understood that the same element 100 is also suitable for a door or sash. Specifically, Figure 1 shows a 5 chamber frame profile. It will be readily apparent that door and sash profiles can differ in geometry, size and shape. The element 100 comprises a hollow prismatic outer section 10 and a number of internal structural supports 18. The supports 18 are arranged to increase the strength of the element 100 and improve its resistance to bending or twisting. The supports 18 also form sealed internal compartments which improve the heat insulating properties of the frame.

The outer section 10 has a substantially continuous outer surface 12 and a substantially continuous inner surface 16.

The outer surface 12 comprises at least one decorative surface 14, which is visible when the element 10 is installed in a window cavity. The decorative surface 14 is a face which is visible to an external observer. The decorative face may or may not be foiled or otherwise decorated,and may have the same appearance to the remainder of the outer surface, such as white uPVC. In some embodiments, the rear face of the outer surface 12 may also be a decorative surface. When installed in a window cavity, it should be understood that the lower portion 112 of the outer surface 12 will be adjacent to the inner surface of the window cavity, and also that the upper portion 114 of the outer surface 12 will be adjacent a glazing pane or a sash frame element located within the window frame.

The inner surface 16 is formed predominantly of upper 116, lower 118, front 120, and rear 122 sections. The inner surface 16 is intersected by the supports 18 at connection points 110, but it will be understood that the inner surface is substantially continuous despite these intersections.

The element 100 is cut from a length of extruded section. Therefore, an extended length of extruded section can be manufactured into several elements 100 of varying lengths. When it is desired to form a joint between two elements 100, the end surface 124 of each section 100 is melted using a hot plate, and then forced against the melted end surface 124 of the other element 100 to form a weld bead. When the weld bead solidifies, the force can be reduced and the two elements 100 are then welded together.

However, when forcing two melted end surfaces 124 together, the weld bead is formed adjacent the end surface 124. Therefore, a weld bead appears on the outer surface 12 of both of the elements 100 which have been welded.

A weld bead is not desirable on a window frame, particularly on the decorative surface 14 which is visible when the window frame is installed. Therefore, when forming window frame joints with prior art elements 100, the external weld bead formed on the outer surface 12 is often trimmed, knifed, feature-grooved, colour-finished, penned, and/or painted, which are relatively highly labour-intensive, and therefore expensive, activities compared to the relatively low cost of the elements 100.

Figure 2 shows a weldable window frame element 200 according to the present invention. Similarly to the prior art element 100, the element 200 of Figure 2 comprises an outer section 20 having an outer (or outermost) surface 22 and an inner (or innermost) surface 26. Further similarly to the prior art element 100, the outer surface 22 extends around substantially the outside of the entire outer section 20, and the inner surface 26 extends around substantially the inside of the entire outer section 20. The outer section 20, and in particular, the inner surface 26 define an internal space 212 of the element 20. The internal space 212 is the volume defined by the projected area within the boundary of the inner surface 26 along the entire length of the element 200.

Furthermore, the element 200 also comprises a core section 28 which extends through the entire length of the element 200. The core section 28 comprises a box section 214 and a number of bridging elements 210 that space the box section 214 of the core section 28 from the outer section 20. A spacing gap 228 is thereby formed between the outer section 20 and the box section 214 of the core section 28 around the entire periphery of the core section 28, except where a bridging element 210 is present. The spacing gap 228 is an air gap.

In Figure 2, the core section 28 is shaded differently to the outer section 20 to clearly denote the separate sections. However, it will be understood that the core section 28 and the outer section 20 may be manufactured together from the same material, such as by an extrusion process.

In this instance, the element 200 is formed from an extended length of extruded section. The element 200 is cut to a predetermined length such that the core section 28 and the outer section 20 have the same length.

The preparation of the element 200 for welding will be described further with reference to Figures 3a-d and Figure 4. Figures 3a-d show a simplified outer section 20 and core section 28 with fewer bridging elements 210 for ease of illustration. Figures 3a and 3b show the element 200 before a removal operation and Figures 3c, 3d, and 4 show the element 200 after a removal operation ready for welding.

Figures 3a and 3b show the element 200 in end and side views respectively immediately after the element 200 has been cut to a desired length from an extended length of extruded section. In Figure 3b, it is clear that the end face 224 of the outer section is flush with the end face 226 of the core section. In Figure 3b, a dashed line 219 shows the desired location of an abutment face 216 on the outer section 20 to be formed by a removal operation.

A removal operation takes place to remove the portion of the outer section 20 to the right of the dashed line 219 in Figure 3b. The removal operation can be a milling operation, a sawing operation, a melting operation, a cutting operation, or any other type of material removal operation. The removal operation may also remove a portion of one or more of the bridging elements 210 to the right of the dashed line.

Following the removal operation, the element 200 takes the form shown in Figures 3c, 3d, and 4. In particular, Figures 3c and 3d show the element 200 in end and side views respectively. In these Figures, it can be clearly seen that an abutment face 216 has been formed on the outer section 20. Furthermore, it can be seen that a weld face 218 has been formed on the core section 28.

The abutment face 216 is stepped back from the weld face 218 by a length or distance x as shown in Figure 3d. The portion of the core section 28 which protrudes from the abutment face 216 is the sacrificial weld portion 220. In the illustrated embodiment, the weld portion 220 may comprises just the box section 214 of the core section. However, dependent upon which of the bridging sections 210 are removed during the removal operation above, some or all of the bridging sections 210 may also form the weld section 220. Preferably, all of the bridging sections 210 are removed.

As shown more clearly in Figure 4, the sacrificial weld portion 220 protrudes significantly from the abutment face 216 and is formed solely of the box section 214 of the core section. In the illustrated embodiment, the bridging sections 210 have been removed from the sacrificial weld portion 220 during the removal operation, but it will be understood that the bridging sections could be left intact or partially intact and the resulting element 200 would still fall within the scope of the invention.

Figures 5a-c show a weld operation for the formation of a butt joint comprising two weldable elements 200 according to the present invention. These figures show the elements 200 in partial cutaway. Above the dashed line 221, the outer section 20 of each section is shown in cross section to reveal the core section 28 beneath.

In Figure 5a, the weld face 218 of each element 200 has been heated, with a hot plate or otherwise to a substantially molten state. The elements 200 are then forced towards one another linearly with the weld faces 218 axially aligned. It will be understood that contacting the elements 200 linearly will form a butt joint. If the elements are cut at an angle and forced together at right angles, a mitre or corner joint can also be formed in a similar fashion to that described here in relation to Figures 5 a-c.

Figure 5b shows the elements 200 shortly after contact has been made between the weld faces 218 and force continues to be applied to urge the elements 200 toward one another. The weld faces 218 and the sacrificial weld portions 220 of each element 200 can be seen in Figure 5b to have joined together and to have begun to deform to create a weld bead 230.

The weld bead 230 expands from all points of contact between the sacrificial weld portions 220. In particular, the bead is formed both inside and outside the box section 214, but the internal weld bead is not visible in Figure 5 as the box section is not shown in cutaway. However, the weld bead 230 can be seen to expand laterally from the core section 28 towards the outer section 20 as the sacrificial weld sections 220 deform and are converted into the weld bead 230. The weld bead 230 can also be seen to expand axially along the elements 200 into the spacing gap 228.

In Figure Sc, the elements 200 have been forced together such that the abutment faces 216 of both elements 200 have come into abutment. The sacrificial weld portions 220 have been completely deformed to form the weld bead 230. The weld bead 230 has expanded both laterally and axially within the spacing gaps 228 of the elements. If further expansion of the weld bead 230 is required, the weld bead may only expand axially along the spacing gaps 228 as it is limited from further lateral expansion by the outer sections 20.

Once the abutment faces 216 of the two elements 220 come into abutment, the elements can no longer move further, so the urging force is continued for a short period while the weld bead 230 solidifies, after which time the urging force is removed, and the joint is formed.

The core sections 28 of the two elements 200 may then be regarded as welded together, while the outer sections 20 are simply in abutment. Therefore, the joint between the two elements has the strength and durability of a welded joint, while retaining the external aesthetics and smooth transition of a simple butt joint.

As shown in the illustrated embodiment of Figure 5c, the weld bead 230 can be designed such that the weld bead 230 spans the spacing gap 228 completely and contacts the inner surfaces 26 of the elements 200. Therefore, the weld bead 230 supports the outer sections 20 at the abutment faces 216 and prevents sagging of the outer sections at the weld location, or deformation due to external forces applied at the location of the joint. Furthermore, as the weld bead 230 extends around the entire periphery of the outer sections 20, the weld bead 230 forms a seal at the abutment faces 216 to prevent the ingress of fluid into the spacing gap 228.

On formation of the joint, the weld bead 230 is prevented from escaping from the spacing gap 228 and the outer sections 20 by the abutted sections 20. Therefore, no part of the weld bead 230 is present exterior to the outer sections 20 and therefore there is no need for removal or cleaning of external bead formation or other methods of containing the weld bead as it forms.

Figures 6 a-c show a similar welding operation to Figures 5a-c, but with three of the aforementioned elements 200 being joined to form a 'T' joint. Figure 6a shows the constituent parts of the joint before their assembly and welding operations. Two elements 301,302 according to the present invention are machined to provide a perpendicular end face and an angled end face, and a respective removal operation on each element 301,302 is performed to expose a sacrificial weld section for each element. The removal operation creates a perpendicular abutment face 304, an angled abutment face 305, a perpendicular weld face 306, and an angled weld face 307 on each of the elements 301,302.

In a first weld operation, a butt joint is created between the elements 301,302 substantially as described in relation to Figures 5a-c using the perpendicular abutment faces 304 and the weld faces 306. Following the first weld operation, the two abutment faces 304 are in abutment and the weld faces 306 are welded together.

Following completion of the first weld operation, the joint assembly appears as shown in Figure 6b. A third element 303 is then prepared for welding to complete the joint. The element 303 is machined with two angled end faces to form an arrowhead. A removal operation is performed upon the angled faces to create two angled abutment faces 308 and two angled weld faces 309.

A second weld operation is then performed substantially as described in relation to Figure 5 a-c to abut the angled abutment faces 308 of element 303 against the angled abutment faces 305 of the elements 301,302. After the second weld operation, the 'T' joint is completed as shown in Figure 6c.

In an alternative embodiment, the 'T' joint of Figures 6a-c may be a reverse butt joint. Each of the elements 301,302 may be formed from a section having the same '12 profile, which is reversed and welded end-to-end in the first weld operation to create a reverse butt weld. In this way, elements 301,302 could be formed from a single length of 1' profile. The single length could be cut into two shorter elements, the first being element 301 and the second being element 302. before the first weld operation, the second element 302 can be rotated to thereby create the reverse butt weld. In this alternative embodiment, element 303 may then be a reversible 2' profile element which aligns with the profiles of elements 301,302 and is welded during the second weld operation to create the reverse butt joint.

Figure 7 illustrates the constituent parts of an alternative embodiment of the invention in the form of a window frame element 400. The element 400 comprises an outer section 42 as shown in Figure 7a and a core section 44 as shown in Figure 7b which is separate from the outer section 42.

The outer section 42 comprises a substantially continuous outer surface 46 and a substantially continuous inner surface 48. The inner surface 48 is intersected with a plurality of guide rails 410 which extend along the length of the outer section 42. It will be understood that the guide rails 410 need not extend along the entire length of the outer section 42 and could be present along only portions of the length of the outer section 42 if desired.

The element 400 further comprises a core section 44 as shown in Figure 7b. The core section is shaped such that its outer surface 412 conforms to the inner surface 48 of the outer section 42. Furthermore, the core section comprises a plurality of guide grooves 414 shaped to compliment the guide rails 410 of the outer section 42. Therefore, the core section 44 can be inserted linearly into the outer section 42 to create the element 400. The complimentary shaping of the guide rails 410 and the guide grooves 414 provides that the core section 44 is moveable only in the axial direction relative to the outer section 42.

To create a welded joint between two elements 400, the outer section 42 of each of the sections 400 is first cut to a desired length L. The end face of the outer section 42 is the abutment face 416. The core section 44 is then cut to a length L+X, where X is the length of the sacrificial weld portion required. If a welded joint is required at both ends of the element 400, then the core section 44 is cut to a length L+2X. The cut end face of the core section 44 becomes the weld face 418.

The remainder of the welding process will be described in relation to a welded joint formed at one end of an element 400, but it should be understood that the same process can be repeated at the opposing end of the element 400 by repeating the welding process.

As the core section 44 is longer than the outer section by a distance of X, the core section is arranged such that the weld face 418 protrudes past the abutment face 416 by a distance of X. If desired, the core section 44 and the outer section 42 can be temporarily secured in this arrangement to avoid relative movement during the welding operation. The weld face 418 can then be heated and secured to an opposing weld face 418 of another element 400 as per the discussion in relation to Figure 5.

If desired, the guide rails 410 can be designed such that they provide a spacing gap between the outer surface of the core section 44 and the inner surface 48 of the outer section. For example, the guide rails 410 could be taller than the guide grooves 414 to thereby provide a spacing gap. Furthermore, guide grooves 414 may not be required if a sufficient number of guide rails 410 are provided, as the outer surface of the core section 44 can abut the guide rails 410 to provide a spacing gap and prevent lateral movement of the core section 44 relative to the outer section 42.

To this end, a further example of an element 450 according to the present invention is shown in Figure 7c. In this embodiment, an outer section 452 and a core section 454 are provided. On the outer section 452, the guide rails 456 have a simple rectangular cross-section, which protrudes from the inner surface by a distance D. The core section 454 is designed such that its outer surface 458 is similar in shape to that of the outer section 452, but each of its dimensions is reduced by 2D. Therefore, when the core section 454 is inserted into the outer section 452, the core section is spaced from the outer section by a distance D by the guide rails about its entire periphery, thereby providing a spacing gap 228.

In an embodiment where no spacing gap is provided, as shown in Figure 7a and 7b, the sacrificial weld portion can be designed such that the weld bead created is sufficiently small that it can be contained between the two abutment faces of the elements 400 and does not expand beyond the outer surface 46 of the outer section 42.

This can be assisted by providing the weld face 418 as a plurality of peaks and troughs, whereby the material of the peaks is melted during the welding process and flows in to the troughs rather than onto the outer surface 46 of the outer section 42.

Therefore, even in the absence of a spacing gap, it will be understood that an element according to the present invention can provide a substantially smooth joint transition and avoid the creation of a weld bead above the outer surface of the outer section.

Figures 8a-d shows a number of further embodiments according to the present invention. For each core section of Figure 8, a complimentary outer section (not shown) is provided.

The embodiments of Figures 8a-d each take the form of a 'plug-in' section which is inserted into an internal space defined by an inner surface of a respective outer section.

Figure 8a shows a core section 500 comprising an insert section 502 and a weld face 508. The insert section 502 comprises an attachment means 504 formed of two locking screws 512 which can be rotated to extend a locking element 506. The locking screws 512, of which there are two arranged axially into the weld face 508, comprise an off-centre cam 514 which comprises the locking element 506. The insert section 502 is inserted into the internal space of the outer section and the attachment means 504 can be actuated to lock the core section 500 in place within the internal space. The weld face 508 is formed of a plate of weldable material. The plate is of slightly larger dimensions than the insert section 502 such that a shoulder 510 is formed on the core section 500. When the core section 500 is fully inserted into the outer section, the shoulder 510 abuts the abutment face of the outer section, thereby preventing the core section from being over-inserted into the outer section.

Once the core section has been attached to the outer section via the attachment means 504, the weld plate forms a weld face 508 and a sacrificial weld portion in a similar way to the other embodiments described herein. A weldable element formed of the core section 500 and a complimentary outer section may then be welded as per the description relating to other embodiments hereinbefore described. As the locking screws are arranged in the weld face 508, the weld face 508 melts around the heads of the locking screws 512 during the welding operation, thereby permanently securing the locking screws 512 in the locked position with the locking elements 506 extended. Therefore, after the welding operation, the core section 500 may not be removed from the outer section.

Figure 8b shows a core section 600 formed of an insert portion 602 comprising attachment means 604 comprising hooks, pins, or a plurality of sprung biased gripping elements. A weld portion 608 is provided in a frame arrangement. The attachment means 604 is provided on a reverse of each of the frame members 610 forming the weld portion 608. The outer section for use with the core section 600 has complimentary frame portions which can be engaged by the attachment means 604 to secure the core section 600 in the internal space of the outer portion. The weld portion, similarly to the core section 500, forms a weld face and a sacrificial weld portion in accordance with the other embodiments described herein. In particular, in this embodiment, the weld face is not a continuous flat surface as with core section 500, but is only present where the frame members 610 are located. A weldable element formed of the core section 500 and a complimentary respective outer section may then be welded as per the description relating to other embodiments hereinbefore described.

Figure 8c shows a core section 700 comprising an insert portion 702 and a weld portion 708. The core section 700 operates in a similar manner to the core section 500. However, the attachment means of the core section 700 has a shape and size relative to the outer section so as to form an interference fit between the insert portion and the inner surface of the outer section. The weld portion, similarly to the core section 500 forms a weld face and a sacrificial weld portion in accordance with the other embodiments described herein. In the illustrated embodiment, the weld portion is ribbed, corrugated, or profiled such that the surface area of the weld face is increased compared to a typical flat plate. Therefore, the weld contact area is increased. An element formed of the core section 700 and a complimentary outer section may then be welded as per the description relating to other embodiments hereinbefore described.

Figure 8d shows a core section 800 comprising an insert portion 802 and a weld portion 808. The core section 800 operates in a similar manner to the core section 500. However, the attachment means of the core section 800 comprises a twist lock between a twist lock element 806 of the outer section 810 and a complimentary twist lock element 804 of the insert portion. The weld portion 808, similarly to that of the core section 500, forms a weld face and a sacrificial weld portion in accordance with the other embodiments described herein. An element formed of the core section 800 and a complimentary outer section may then be welded as per the description relating to other embodiments hereinbefore described.

It will be understood that the weldable elements described herein are for exemplary purposes only, and that there are many types of weldable elements compatible with the present invention.

The present invention is not limited to the specific embodiments described herein. Alternative arrangements and suitable materials will be apparent to a reader skilled in the art.

Claims

CLAIMS1. A weldable element comprising: an outer section having a outermost surface, a innermost surface, and an abutment face; a core section having a weld face; wherein the innermost surface defines a space; and wherein the core section is arranged at least partially in said space and such that the weld face protrudes beyond the abutment face by a predetermined distance (x, X) to thereby provide a sacrificial weld portion of the core section.
2. A weldable element as claimed in claim 1, wherein the outer section and the core section are formed as integral parts.
A weldable element as claimed in claim 1 or claim 2, wherein a spacing gap is provided between the innermost surface and the core section.
4. A weldable element as claimed in claim 3, wherein the core section comprises one or more bridging elements that space the remainder of the core section from the innermost surface of the outer section to thereby provide the spacing gap.
5. A weldable element as claimed in any of claims 1 to 4, wherein a portion of the outer section is removed by a removal operation to form the abutment face.
A weldable element as claimed in claim 5, wherein the removal operation forms the abutment face at a predetermined distance from the weld face to thereby form the sacrificial weld portion.
A weldable element as claimed in claim 1, 3, or 4, wherein the core section is provided as a separate component to the outer section.
8. A weldable element as claimed in claim 7, wherein the core section comprises an insert portion for insertion into the internal space and a weld portion comprising the weld face and the sacrificial weld section.
9. A weldable element as claimed in claim 8, wherein the insert portion comprises attachment means to attach the core section to the outer section
10. A weldable element as claimed in claim 9, wherein the attachment means comprises an interference fit between an the insert portion and the innermost surface of the outer section.
11. A weldable element as claimed in claim 9, wherein the attachment means comprises a mechanical connection.
12. A weldable element as claimed in claim 9, wherein the attachment means comprises an adhesive.
13. A weldable element as claimed in any of claims 8 to 12, wherein the weld portion comprises one or more of: a) a flat plate of weldable material; b) a profiled plate of weldable material; or c) a frame of weldable material.
14. A weldable element as claimed in any preceding claim, wherein the space is an internal space within the outer section.
15. A weldable element as claimed in claim 14, wherein the core section is located entirely within the internal space.
16. A weldable element as claimed in any preceding claim, wherein the weldable element is an elongate weldable element having a length.
17. A weldable element as claimed in claim 16, wherein the outer section is formed of a shaped section which is repeated along the length of the weldable element.
18. A weldable element as claimed in claim 16, wherein the outer section is substantially prismatic.
19. A weldable element as claimed in claim 16, wherein the outer section has a uniform cross-sectional shape and size along the length of the outer section.
20. A weldable element as claimed in any preceding claim, wherein the weldable element comprises a first end and wherein the abutment face and the weld face are located proximal the first end to thereby form the sacrificial weld section.
21. A weldable element as claimed in claim 20 when dependent upon any of claims 1 to 7 or 14 to 18, wherein the core section extends within the internal space along substantially all of the length of the weldable element.
22. A weldable element as claimed in any preceding claim, face wherein the weldable element comprises a second end, and wherein a second abutment face and a second weld face are located proximal the second end to thereby form a second sacrificial weld section
23. A weldable element as claimed in claim 22 when dependent upon claim 21, wherein a second core section is arranged at least partially within the internal space and such that the second weld face protrudes from the second abutment face by a predetermined distance to thereby provide the second sacrificial weld-able section.
24. A weldable element as claimed in any of claims 21 to 23, wherein the core section is constrained within the internal space such that it may move only along an axis of the length of the weldable element.
25. A weldable element as claimed in claim 24, wherein the core section is shaped such that an outer surface of the core section is in contact with substantially all of the innermost surface of the outer section.
26. A weldable element as claimed in any preceding claim, wherein the outer section defines a closed loop.
27. A weldable element as claimed in any preceding claim, wherein the core section defines a closed loop.
28. A weldable element as claimed in any preceding claim, wherein the weldable element is a plastic element.
29. A weldable element as claimed in any preceding claim, wherein the weldable element is a window, door, or sash frame element.
30. A window, door, or sash frame comprising one or more window, door, or sash frame elements as claimed in claim 29.
31. A joint comprising a first weldable element as claimed in any one of claims 1 to 25 and a second weldable element as claimed in any one of claims 1 to 29.
32. A joint as claimed in claim 31, wherein the weld face of the first weldable element is welded to the weld face of the second weldable element such that the abutment faces of the first and second weldable elements are located in abutment with one another.
33. A joint as claimed in claim as claimed in claim 31 or 32, wherein the joint is a window, door, or sash frame joint.
34. A method of constructing a joint as claimed in any of claims 31 to 33, wherein the method comprises the steps of: heating the weld faces of at least one of, and preferably both of, the first and second weldable elements; contacting the weld faces of the first and second weldable elements against one another; and applying a force to the weldable elements to thereby maintain the weld faces of the first and second elements in reciprocal contact and compress the sacrificial weld portions of the first and second weldable elements to thereby form a weld bead.
35. A method of constructing a joint as claimed in claim 34, wherein the weld bead is formed entirely within a volume defined by the outermost surfaces of the first and second weldable elements.
36. A method of constructing a joint as claimed in claim 34, wherein the weld bead is formed entirely within a volume defined by the innermost surfaces of the first and second weldable elements.
37. A method of constructing a joint as claimed in claim 34 or 35, wherein the weld bead is formed at least partially between the abutment surfaces of the first and second weldable elements.
38. A method of constructing a joint as claimed in claim 37, wherein any weld bead formed external to the outermost surface of the outer section is severed by the abutment of the abutment faces of the first and second weldable elements.
39. A method of constructing a joint as claimed in any of claims 34 to 37 when the first and second weldable elements are as claimed in claim 3 or 4, wherein the weld bead is formed within the spacing gap.
40. A method of constructing a joint as claimed in any of claims 34 to 39, wherein the weld bead abuts the innermost surfaces of the outer sections of the first and second weldable elements.
41. A method as claimed in any of claims 34 to 38, wherein the method is a method of constructing a window, door, or sash frame joint.
42. A weldable element substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
43. A joint substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
44. A method of constructing a joint substantially as hereinbefore described with reference to and as shown in the accompanying drawings.