Improved Window Stay and Assembly Method

Abstract

An improved window stay is provided comprising a sash-mounting member configured to mount against the sash and a frame-mounting member configured to mount against a frame, 5 and a pair of linkage arms, pivotably connected between the sash-mounting member and the frame-mounting member, to form a four-bar linkage. In particular, the rotatable connection between respective links in the four bar linkage, is formed in stages in which a precursor stage involves forming a hollow annular boss in at least one linkage arm from aluminium at a T4 temper, and subsequently processing the at least one linkage and hollow annular boss to a 10 higher temper (for example T6), and then closing the pivoting friction connection. 20 25 23 81 19 29 S ep 2 02 5 S e p 2 0 2 5 2 3 8 1 1 9 2 9 2 0 2 5

Description

FIELD OF THE INVENTION The present invention relates to an improved window stay. More particularly, but not exclusively, it relates to a window stay for use with extruded joinery and a window assembly utilising the window stay, having improved pivoting friction joints between members. BACKGROUND OF THE INVENTION Window stays of various types have existed for hundreds of years, being mechanisms used to guide the opening and closing of windows and to temporarily lock or hold them at certain positions, at or between fully open and fully closed. Window stays are used with both casement windows which are hung from the side and pivot on a vertical axis to open / close, and awning windows which are hung from the top and pivot on a horizontal axis to open / close. One type of window assembly becoming increasingly common in modern times is that made from extruded profiles, typically aluminium. These types of window assemblies are convenient because much of the work in preparing the assembly can be done offsite and then transported to site for installation. Casement and awning windows made in this manner typically comprise a window sash which holds the window pane, and a window frame which mounts within the opening in the building wall. Window stays are used to connect between the sash and frame to allow opening and closing of the window. One common type of window stay is of a four-bar linkage type, incorporating a pair of plates that are fastened against the sash and window frame respectively. One example of such a window stay is shown in NZ Patent No. 573233, in which friction joints are also employed at the pivots between the links and the sash mounting plate and window frame mounting plate, to help retain the window in a desired position. This patent is incorporated by reference, as an example 4 bar window stay including friction pivot joints. Although assembling windows in this way allows for efficient fabrication and good performance compared to more traditional window joinery methods, the friction joints between respective elements of the four-bar linkage may wear over time and / or may produce a different magnitude of friction over time. It is desirable that the window stays provide an appropriate (and / or desired) magnitude of friction so that the opening and closing action of the window is smooth, and reliable. In addition, it is generally desirable that the magnitude of friction is relatively consistent and / or relatively constant over the life, or expected design life of the window stay. Further still, it may be an advantage in some applications to be able to 2025238119   16 Sep 2026 control the magnitude of friction provided by the frictions joints when manufactured, to allow design to a desirable level, that may be different for varying scenarios. It is therefore desirable to improve the consistency of the friction joints, and / or to improve the expected performance over the life-span of the friction joints. 5 It is an object of the present invention to provide a window stay and assembly which overcomes or at least partially ameliorates some of the abovementioned disadvantages or which at least provides the public with a useful choice. BRIEF DESCRIPTION OF THE INVENTION According to a first aspect, the invention broadly comprises a method of forming a 10 window stay comprising at least one pivoting friction connection between a first component and a second component, said pivoting friction connection being formed by: providing said first component in a first low temper state, forming a hollow annular boss having an outer bearing surface from material of said first component, 15 subsequently tempering said first component and said hollow annular boss to a second high temper state, and swaging said hollow annular boss to form said pivoting friction connection between said first component and said second component. 20 In another aspect said window stay is for connection between a window sash and a window frame. In another aspect the window stay comprises a sash-mounting member, a frame-mounting member, and a pair of aluminium linkage arms, each rotatably connected at each end by a 25 said pivoting friction connection between a respective sash-mounting plate and framemounting plate, such that the window stay forms a four-bar linkage moveable between an open condition and a closed condition. In another aspect said window stay includes four said pivoting friction connections and each 30 is formed by: providing a linkage arm in a first low temper state, 2025238119   29 Sep 2025 forming a hollow annular boss having an outer bearing surface from material of said linkage arm, subsequently tempering said linkage arm and said hollow annular boss to a second high temper state, and swaging said hollow annular boss to form said pivoting friction connection between said linkage arm and said respective mounting plate. In another aspect a polymer bushing is provided between each said hollow annular boss and a said respective mounting plate in said pivoting friction joint. In another aspect the bushing is nylon. In another aspect the pair of linkage arms are of 6060 aluminium alloy. In another aspect the pair of linkage arms are of 6063 aluminium alloy. In another aspect said high temper state is T6. In another aspect said low temper state is T4. In another aspect the pair of linkage arms are formed by stamping. In another aspect the pair of linkage arms are stamped from T4 tempered aluminium. In another aspect the sash mounting plate and window mounting plate are aluminium. In another aspect the sash mounting member and the frame mounting member are aluminium. In another aspect the step of swaging said hollow annular boss to form said pivoting friction connection, is an orbital forming process. 2025238119   16 Sep 2026 In another aspect, in the closed condition, the sash-mounting and frame-mounting members are aligned such that they are parallel. In another aspect the stay further comprising a limit stop mounted on the frame-mounting plate adjacent a pivot point of one of the linkage arms, the limit stop engaging the linkage 5 arm when the window stay is in the open condition so as to prevent further pivoting. In another aspect the window stay including a pivoting friction connection manufactured according to the method of any one of the preceding clauses. 10 In another aspect the window assembly including a window stay manufactured according to the method of the preceding clause. Other aspects of the invention may become apparent from the following description which is given by way of example only and with reference to the accompanying drawings. 15 As used herein the term “and / or” means “and” or “or”, or both. As used herein “(s)” following a noun means the plural and / or singular forms of the noun. The terms “high temper” state and “low temper” state are intended to be relative metallurgical states of heat treating of an alloy. For example, the “T?” designation indicates the 20 level of temper, and generally a higher number will mean a harder material property. The process and means for achieving various temper states of an alloy are known in the art. The term “comprising” as used in this specification and claims means “consisting at least in part of”. When interpreting statements in this specification and claims which include that term, the features, prefaced by that term in each statement, all need to be present but 25 other features can also be present. Related terms such as “comprise” and “comprised” are to be interpreted in the same manner. In this specification, where reference has been made to external sources of information, including patent specifications and other documents, this is generally for the purpose of providing a context for discussing the features of the present invention. Unless 30 stated otherwise, reference to such sources of information is not to be construed, in any jurisdiction, as an admission that such sources of information are prior art or form part of the common general knowledge in the art. 2025238119   29 Sep 2025 For the purpose of this specification, where method steps are described in sequence, the sequence does not necessarily mean that the steps are to be chronologically ordered in that sequence, unless there is no other logical manner of interpreting the sequence. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described by way of example only and with reference to the drawings in which: Figure 1 shows a partial perspective view of a window stay connecting a window sash and frame; Figure 2     shows a perspective view of a four-bar window stay; Figure 3     shows an exploded view of the window stay of Figure 2, showing the undeformed components of the linkages; Figure 4 shows a semi-exploded view of the window stay of Figure 2, showing the connection between the frame plate and linkages complete, and the connection between the sash plate and linkages exploded; Figure 5a shows a cross section exploded assembly view of a mounting plate, bushing and linkage; Figure 5b shows a cross section assembled view of the mounting plate, bushing and linkage of Figure 5a, shown assembled and with the swaging dies; Figure 6 shows a semi-assembled perspective view of the frame mounting plate and linkages assembled. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS As illustrated in figure 1, there is provided an awning type window assembly 1 comprising a window frame 2, a sash frame 3 (shown transparent to aid viewing of the connecting stay), pivotably mounted to be openable and closable within the window frame 2. The mounting of the sash frame 3, is by window stay(s) 4, which will now be described in more detail. As noted above, the window stay assembly 4 is for connection between a window sash 3 and a window frame 2, which collectively form part of the window assembly 1. However, the window assembly 1 preferably comprises a pair of window stays 4 (not shown) which mirror each other and are connected on opposing sides of the sash 3 and frame 2, as is the typical arrangement for casement and awning window assemblies, and is well known. 2025238119   29 Sep 2025 As shown in the Figures, the window stay 4 comprises a sash-mounting plate member 5, a frame mounting plate member 6, and a pair of linkage arms 7,8 pivotably connected therebetween. The upper and lower linkage arms 7,8 respectively cause the window stay 4 to form a four-bar linkage moveable between an open condition and a closed condition. This four bar linkage provides an essentially pivoting motion between the sash frame 3 and the window frame 4, but with a moving pivot point that ensures the sash frame 3 moves outward as it pivots, and better clears the window frame 2 during opening. Typically, window stays are manufactured by extruding an aluminium alloy, such as 6060, and / or 6063 for example, which can be readily formed by extrusion, and can also be tempered to produce different material properties. The window stay 4 comprises sash and frame mounting plates 5,6 respectively, and upper and lower link arms 7,8 respectively, which are coupled at each end to the plates 5,6, via friction pivot bearings 9. One or more of the pivot bearings 9 are preferably of the form and manufacturing method further described herein. It will be appreciated that in the most preferred configurations, each friction pivot joint of the four-bar linkage, is as described, being: • pivot joint between upper link 7 and sash mounting plate 5, • pivot joint between lower link 8 and sash mounting plate 5, • pivot joint between upper link 7 and window mounting plate 6, • pivot joint between lower link 8 and window mounting plate 6. However, it is also anticipated that only 1, 2 or 3 of the friction pivot bearings of each four-bar linkage may utilise the preferred form as described. With reference to Figures 3 & 4, exploded and semi-exploded illustrations are provided of the four bar linkage and pivot bearing(s) 9, therebetween. In preferred configurations, each pivot bearing 9 is of the same form, and for convenience will be described singly, and with particular reference to Figures 5a & 5b. The pivot bearings 9 preferably comprise an assembly of the respective link arm 7,8 and a respective mounting plate 5,6, with a wear resistant bushing 15 between. As illustrated in Figure 5a, a hollow annular boss 10 is formed by having been drawn from the respective link arm 7,8 material. Accordingly, the hollow annular boss 10 is an integral part of the link arm component 7,8. As best illustrated in Figure 5a, the annular boss 10 has a free end and an outer wall surface 11 forming a bearing surface. 2025238119   29 Sep 2025 The mounting plate 5,6 comprises an opening 12 and an annular wall 13 around the opening which projects inwardly from the periphery of the opening and then turns at an annular step 14 to terminate in a generally cylindrical portion. During assembly, the annular boss 10 is located within the bushing 15, and both are fitted within opening 12 of the mounting plate, and subsequently the free end portion of the hollow annular boss 10 is pressed and / or swaged over to close the joint. The resulting joint 9, may provide friction / resistance to movement, while allowing relative rotation between the link arm and mounting plate. In preferred embodiments the free end portion of the hollow annular boss 10 is pressed over to close the joint 9 with the bushing 15 under sufficient pressure to create a desired level friction (resistance) within the completed bearing. In other embodiments the free end portion of the hollow annular boss 10 is pressed over to close thejoint but without significant friction-creating pressure in the bearing, to result in a ‘free’ moving bearing 9. Typically, if the link arm 7,8 is of uniform thickness, the resultant hollow annular boss 10 will have a cross sectional wall thickness which is less than that of the link arm from which it is drawn. A plastic bushing 15, for example of Nylon or other wear resistant plastics material is located over the annular boss 10 so that the flange 16 lies against the surface of the arm 7,8. The mounting plate 5,6 and link arm 7,8 are brought together so that the annular boss 10 and the sleeve 15 extend through, with the flange 16 of the sleeve sitting between to prevent metal to metal contact and create friction between the arm and plate, as shown in Figure 5b. Figure 5a shows the annular boss 10 formed in the arm 7,8 before assembly and closing of the joint 9, and the plastic bushing 15 or friction pad before assembling the joint 9. Production Method As noted above, the components of the window stay 4, are preferably of an aluminium alloy such as 6060, and / or 6063. In particular, the link arms 7,8 are preferably of 6060 aluminium, or similar alloy. During manufacture, the annular boss 10 can be formed by establishing a small hole in the link arm that determines the centre of the resultant pivot bearing 9, and then drawing metal from around the hole to form the boss 10. The length of the boss 10 is such that once the joint is closed, the free end of the boss 10 preferably does not extend past the lower edge or surface of the mounting plate. 2025238119   29 Sep 2025 In order to allow such cold forming of the boss 10, it is preferred that the 6060 link arms are provided in a suitable temper state. For example, 6060 aluminium is typically provided as a bare extrusion in a low temper state (for example T4), as this results in moderate strength of the component, and provides high ductility for forming the boss 10, from the material of the link arm 7,8. A T4 temper state, means the link arms have been solution heat-treated and then naturally aged at room temperature to achieve its mechanical properties. For example, blank link arms 7,8 may be formed by stamping an extrusion formed material, and provided in a T4 temper state (which is typical of an extrusion). Subsequently, the stamped link arms may undergo forming of the boss portions 10, by a suitable process such as described above. After the boss 10 is formed, the link arms may undergo additional tempering steps to a higher tempering state, such as T6 for example. The T6 temper state is known and means that the alloy has been heat treated, to achieve higher hardness and strength. For example, heat treatment involves: • heating the link arms to their solution temperature, approximately 482°C for 6060 aluminium, • Holding the arms at this temperature to allow the alloying elements to dissolve and create a supersaturated solid solution, and • Rapidly cooling the link arms by quenching them, usually in water. Further, the ageing step involves: • Heating the link arms to a specific lower temperature for a controlled period. In the case where the link arms are tempered to a T4 state at the time of forming the boss 10, it will be appreciated that further tempering to a T6 state, only requires the additional artificial ageing step of heating the link arms to a specific temperature (typically 160°-190°C) for a controlled period (typically several hours). For example, heating to between 180°C-205 °C for 6-8 hrs. Good results for a 6060 T4 alloy, may be achieved by ageing at 200°C for around 6 hrs, to achieve a T6 temper. 2025238119   29 Sep 2025 Figure 5a shows the arm 7,8 and annular boss 10 before assembly and closing of the joint. At this stage, preferably the link arms have been additionally tempered to a higher temper state (such as T6, or similar), prior to completing the assembly and forming / closing of the pivot joint(s) 9, as described above. 5          While it is anticipated that the link arms 7,8 and the mounting plate 5,6 may all be tempered to a higher temper (such as T6), it has been found that significant advantage can be realised by tempering only the link arms 7,8 (having bosses 10 previously formed). In the resulting pivot joints 9, friction is comparatively consistent and / or relatively constant over the life, (or expected design life) of the window stay. Testing has demonstrated that performance 10 is significantly improved. For example, window stays 4 produced according to a prior art method (not including an additional T6 tempering step after forming the boss 10), failed early when a window was cycled many times with a weight applied to the window sash (see Table 1). Additionally, prior to failure, the gap at the head of the tested window increased significantly (i.e. around 10mm 15 or more in under 1000 cycles). This gap would be expected to significantly affect the performance and / or aesthetic of the window. The windows tested in such extreme loading conditions, are known to be sufficient for normal use. Non-Tempered Boss Weight (kg) # of Cycles Gap at head (mm) 25 1000 14mm 2000 16mm 3300 Fail 50 600 10mm 800 16mm 895 Fail Table 1: Window testing without additional T6 Tempering Step of link arms 2025238119   29 Sep 2025 Aged Tempered @ 200°C for 6 hours Weight (kg) # of Cycles Gap at head (mm) 25 100 0.0 1000 0.0 5000 0.5 10000 1.0 50 100 0.5 1000 2.0 5000 4.5 10000 7.0 Table 2: Window testing with additional T6 Tempering Step of link arms As can be seen by comparing the data in Table 1 & 2 above, the improved window stays maintain acceptable performance, even under the extreme loading conditions of the test, and even at the point the non-improved stays failed entirely. This is a significant improvement in performance. In addition, it has been found that the performance improvement in larger size stays, mean that 10,000+ cycles can be achieved with minimal (or no noticeable) gaps forming at the head of the window, even under extreme loads of 50-100kg. Given 10,000 cycles are considered to be well beyond a 25 year life of the product, the performance benefit is essentially for the full expected life of the product and beyond. Additionally still, the consistency of the friction joints is improved over the life of the stays. This in particular, is a significant advantage, because the smooth motion and ‘tension’ of the of the stays (i.e. the magnitude of the friction resistance to movement), is more constant and / or consistent (i.e. varies less) over the expected life (which typically extends for many years). The performance improvement is believed to be a result of improved dimensional stability and / or hardness in the pivot joint and the boss 10 bearing surface in particular. Using a T6 tempered link arm, or an additional step (e.g. tempering to T6 prior to forming the boss 10) would traditionally be thought to be completely un-desirable, because of the significant reduction in formability of the material. A T6 temper is unsuitable for extruding the link arms, or forming the boss 10, and this is readily understood by those skilled in the art. Similarly, an additional step (e.g. tempering to T6 prior to closing thejoint 9 by swaging etc) was thought to be completely un-desirable, because of the same significant reduction in 2025238119   29 Sep 2025 formability of the material, thereby preventing the boss 10 from being reliably further deformed after assembly to form / swage the pivot joint 9. Further the additional expense of an additional tempering step would be considered unjustified, particularly because any expected performance improvement would be considered to be small, and accordingly an unacceptable trade-off. Further still, it will be appreciated that any attempt to temper the components of the window stay assembly 4, after full assembly would be unworkable due to the polymer bushing 15 and it’s inability to withstand the required temperature of the tempering process. However, against expected knowledge in the art, it has been found that forming the boss 10 in a first temper state, then subsequently applying a second (higher) temper state, before assembling and forming the pivot joint 9, can be achieved reliably and results in significantly superior performance of the window stay. In particular, the improved performance comes from one or more of: • improved dimensional stability of boss 10, • improved cycle life of the assembled window stay components, • improved consistency of the magnitude of friction / resistance to movement provided in the assembled window stay, and • improved consistency of the magnitude of friction / resistance to movement provided in the assembled window stay over a significant portion of the life or design life of the product. Preferred swaging method Further, it has been found that specialised swaging methods for forming the pivot joints 9, may provide additional benefits, and be especially suited (although not essential) for the previously described window stay assembly 4. Orbital forming is a cold forming process using a peen tool held at a fixed angle (of around 4-60) to create a sweeping line of pressure around a rivet or tenon. The orbital movement of the tool progressively collapses the boss 10 down onto the upper material with each rotation, permanently forming or swaging the pivotjoint 9 in the process. Orbital forming creates a low profile, aesthetically appealing finish, that is particularly suitable for assembling 2025238119   29 Sep 2025 window stays 4 of the type described, while allowing for consistent joint articulation as required. Further still, the progressive nature of the pivot joint 9 forming, provided by orbital forming techniques may assist with the higher temper (e.g. T6) of the boss 10, and reduce potential cracking or splitting of the material during swaging. This in turn may reduce the chance of defective product, that would need to be eliminated in quality control inspections. Accordingly, optional orbital forming of the friction joints 9, may further enhance the performance and / or manufacturability of the improved stays 4 as described above. It will be appreciated that the method and mechanism is described above with reference to a window stay, as this is the most preferred application. However, it is anticipated that other applications may benefit from the improved performance of the friction pivot joint described. To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

Claims

1. A method of forming a window stay comprising at least one pivoting friction connection between a first component and a second component, said pivoting friction connection being formed by:5 providing said first component in a first low temper state,forming a hollow annular boss having an outer bearing surface from material of said first component,subsequently tempering said first component and said hollow annular boss to a second high temper state, and10 swaging said hollow annular boss to form said pivoting friction connection between said first component and said second component.

2. The method of claim 1, wherein said window stay is for connection between a window sash and a window frame.

153. The method of claim 2, wherein the window stay comprises a sash-mounting member, a frame-mounting member, and a pair of aluminium linkage arms, each rotatably connected at each end by a said pivoting friction connection between a respective sash-mounting plate and frame-mounting plate, such that the window stay forms a four-bar linkage moveable20 between an open condition and a closed condition.

4. The method of claim 1 or claim 2, wherein said window stay includes four said pivoting friction connections and each is formed by:providing a linkage arm in a first low temper state,25 forming a hollow annular boss having an outer bearing surface from material of said linkage arm, subsequently tempering said linkage arm and said hollow annular boss to a second high temper state, andswaging said hollow annular boss to form said pivoting friction connection between30 said linkage arm and said respective mounting plate.2025238119   29 Sep 20255. The method of claim 3 or claim 4, wherein a polymer bushing is provided between each said hollow annular boss and a said respective mounting plate in said pivoting friction joint.5   5.     The method of the preceding claim, wherein the bushing is nylon.

6. The method of any one of claims 3 to 5, wherein the pair of linkage arms are of 6060aluminium alloy.10   7.     The method of any one of claims 3 to 5, wherein the pair of linkage arms are of 6063aluminium alloy.

8. The method of claim 6 or claim 7, wherein said high temper state is T6.15   9.     The method of any one of claims 6 to 8, wherein said low temper state is T4.

10. The method of any one of claims 3 to 9, wherein the pair of linkage arms are formedby stamping.20   11. The method of the preceding claim, wherein the pair of linkage arms are stampedfrom T4 tempered aluminium.

12. The method of any one of claims 3 to 11, wherein the sash mounting plate and window mounting plate are aluminium.2513. The method of any one of claims 3 to 13, wherein the sash mounting member and the frame mounting member are aluminium.

14. The method of any one of the preceding claims, wherein the step of swaging said 30 hollow annular boss to form said pivoting friction connection, is an orbital forming process.

15. The method of any one of claims 3 to 13, wherein in the closed condition, the sashmounting and frame-mounting members are aligned such that they are parallel.2025238119   16 Sep 202616. The method of any one of claims 3 to 14, further comprising a limit stop mounted on the frame-mounting plate adjacent a pivot point of one of the linkage arms, the limit stop engaging the linkage arm when the window stay is in the open condition so as to prevent further pivoting.

517. A window stay including a pivoting friction connection manufactured according to the method of any one of the preceding claims.

18. A window assembly including a window stay manufactured according to the method 10 of the preceding claim.

Images