AU2007216936B2

AU2007216936B2 - Friction Window Stay

Info

Publication number: AU2007216936B2
Application number: AU2007216936A
Authority: AU
Inventors: Paul Michael Davis
Original assignee: ALUMINIUM SYSTEMS NZ Ltd
Current assignee: ALUMINIUM SYSTEMS NZ Ltd
Priority date: 2006-10-11
Filing date: 2007-09-24
Publication date: 2013-05-30
Anticipated expiration: 2027-09-24
Also published as: NZ550456A; AU2007216936A1

Abstract

A friction window stay for supporting and holding an openable window, comprises: a stay arm (20) formed with a hole (22) at one end; a friction pad (24) formed with a hollow cylindrical protrusion (26), adapted to fit into the hole (22) of the stay arm (20); a 5 frame plate/sash plate (8, 9) formed with a hollow cylindrical protrusion (6), adapted to fit into the hollow cylindrical protrusion (26) of the friction pad (24), and a retaining cap (12) for clamping the stay arm (20) to the frame plate/sash plate (8, 9). The hole (22) of the stay arm (20) is formed with a rim (28) protruding from one side face, and the friction pad (24) is formed with a recess (30) adapted to accommodate the rim (28) when the protrusion 10 (26) of the friction pad ((24) is fitted into the hole (22) of the stay arm (20). @ 24 2\3 8,9 FIGURE 2 8,9

Description

FRICTION WINDOW STAY TECHNICAL FIELD The present invention relates to a friction window stay for supporting and holding 5 an openable window in an optional opened condition. However, it is to be understood that the invention is not to be limited as such. Moreover, because the invention may have many other applications, the prior art and possible applications of the invention discussed below are given by way of example only. BACKGROUND ART 10 Conventional friction window stays for supporting and holding an openable window in an optional opened position generally comprise a stay arm pivotally connected between the openable window frame and the window sash. The stay arm has a punched hole at the pivot ends, into which is inserted a cylindrical hollow protrusion formed on the frame plate/sash plate, and friction is provided by fitting a friction pad in the vicinity of a 15 pivot point between the interior of the punched hole, and the outer circumference of the hollow protrusion, and/or between the side faces of the stay arm and the frame plate/sash plate, and clamping the friction pad between the stay arm and the frame plate/sash plate. A typical example of a friction window stay assembly to which the friction window stay of the present invention is applicable is shown in FIG. 1, and a cross-section of the 20 pivot area of a conventional friction window stay is shown in FIG. 4. As shown in FIG. 1 and FIG. 4, this friction window stay assembly comprises two friction window stays generally indicated by arrow 1. Each of these friction window stays 1 has: a stay arm 2 formed with a punched hole 4 (FIG. 4) at a pivot end into which is inserted a cylindrical hollow protrusion 6 formed on a frame plate 8 or sash plate 9. Friction is provided by 25 fitting a friction pad 10 in the vicinity of the pivot point between the interior of the punched hole 4 and the outer circumference of the hollow protrusion 6, and between the side faces of the stay arm 2 and the frame plate 8 or sash plate 9, and clamping the friction pad 10 between the stay arm 2 and the frame plate 8 or sash plate 9. In this case, a retaining cap 12 is used for clamping the assembly together. The retaining cap 12 30 comprises a cylindrical hollow member with a flange 13 at one end, adapted to deform a tip edge 14 of the friction pad 10 against the stay arm 2 when fitted into the hollow

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protrusion 6 of the frame plate 8 or sash plate 9, and is held in place by expanding the other end 15 so as to engage with a lip 16 formed on the tip of the hollow protrusion 6. With this type of friction window stay the stay arm 2 is now generally made from stainless steel, and the hole 4 is formed by punching. Stainless steel lends itself to being 5 thinner than the previously used aluminium stay arms. However this means that it is more flexible, and the bearing surface area is also less due to being thinner. Moreover it is also much tougher to work with. As can be seen from the cross-section of FIG. 4, the punched hole 4 has a sharp and rough square edge 18 on the die exit side formed by the punching operation. Therefore, 10 since the friction pad 10 is generally made from a plastics material such as nylon, and is thus very susceptible to tearing if the surface of the punched hole 4 is not smooth, then in operation when the stay arm 2 pivots relative to the frame plate 8 or sash plate 9, there is considerable wear between this sharp and rough square edge 18 and the friction pad 10 in this region. This results in a reduced life of the friction window stay assembly 1. 15 It has been proposed to ream out the hole 4 to provide a smoother corner section, and thus reduce the wear, however, this has considerable draw backs such as separate operations, and high wear on the reamer particularly now that tough stainless steel is used for the stay arm. DISCLOSURE OF THE INVENTION 20 It is an object of the present invention to address the above problems with conventional friction window stays, or to at least provide the public with a useful choice. According to a first aspect of the present invention there is provided a friction window stay for supporting and holding an openable window in an optional opened position, comprising: 25 a stay arm formed with a hole at one end; a friction pad formed with a hollow cylindrical protrusion protruding from one side face, adapted to fit into the hole of the stay arm; a frame plate/sash plate formed with a hollow cylindrical protrusion protruding from one side face, adapted to fit into the hollow cylindrical protrusion of the friction pad; 30 and 2 a retaining cap for clamping the stay arm to the frame plate/sash plate with the friction pad therebetweeen, wherein the hole of the stay arm is formed with a rim protruding from one side face of the stay arm in a shape substantially the same as one formed by punching a hole of a smaller 5 diameter than a diameter of the cylindrical protrusion of the friction pad in the end of the stay arm, and then punching with a tapered punch to form a final hole with the rim protruding from one side face such that a bearing surface area of the hole is increased by the hole's circumference multiplied by the rim's protruding length, and the friction pad is formed with a recess surrounding the hollow cylindrical protrusion on the one side face, 10 adapted to accommodate the rim when the protrusion of the friction pad is fitted into the hole of the stay arm, with the one side face of the stay arm mating with the one side face of the friction pad. With such a construction, the bearing surface area of the pivot attachment is increased by the amount of protrusion of the rim on the stay arm. Hence the load on the 15 bearing portion is reduced, and the life of the bearing portion can be increased. Moreover, by providing the rim protruding from one side face, the overall rigidity of the stay arm can be increased which is advantageous in the case of a thin stainless steel stay arm. The rim may be formed by any suitable means whereby the metal in the vicinity of the hole is deformed so as to protrude from one side face of the stay arm. For example, if 20 the rim is formed by a punching operation, then when forming the hole, the metal is plastically deformed and flows out to form the rim, so that there is no longer the sharp and rough square edge of the hole of the stay arm, as with the conventional punched hole stay arm. Hence damage to the friction pad is minimised, and the life of the friction window stay can be increased. 25 According to another aspect of the present invention, there is provided a friction window stay assembly comprising a friction window stay as described above. By using the friction window stay of the present invention in a friction window stay assembly, the life of the friction window stay assembly can be considerably increased compared to conventional friction window stay assemblies, having a plain punched hole or 30 reamed hole in the end of the stay arm. Moreover since the hole can be formed in a single operation for example by punching, the cost can be reduced compared to an assembly having a reamed hole. 3 According to another aspect of the present invention, there is provided a method of manufacturing a friction window stay comprising the steps of: producing a stay arm by deforming a hole in an end of an elongate metal plate using a punch such that a rim is formed around the hole on one side face of the plate and a 5 bearing surface area of the hole is increased by the hole's circumference multiplied by the rim's protruding length; producing a friction pad in the form of a flat member with a cylindrical hollow protrusion on one side face thereof, which is adapted to fit into the hole of the stay arm, and which is formed with a recess surrounding the hollow cylindrical protrusion on the one 10 side face, adapted to accommodate the rim of the stay arm; producing a frame plate/sash plate with a hollow cylindrical protrusion protruding from one side face, adapted to fit into the hollow cylindrical protrusion of the friction pad; and clamping the friction pad between the stay arm and the frame plate/sash plate with 15 the rim of the stay arm accommodated in the recess of the friction pad, and securing in this condition with a retaining cap. According to yet another aspect of the present invention there is provided a method of increasing bearing surface area of a pivot joint of a friction window stay comprising the steps of: 20 deforming a hole in an end of an elongate metal plate constituting a stay arm of the friction window stay using a punch such that a rim is formed around the hole on one side of the plate, and the bearing surface area is increased by the hole's circumference multiplied by the rim's protruding length; and forming a recess in a friction pad of the friction window stay to accommodate the 25 rim. By means of such a method, the bearing surface area of the pivot joint can be increased by the length of the rim formed on one side face of the plate. Moreover, since the hole is formed so that the metal can flow out to form the rim, there is no longer the sharp and rough square edge of the hole of the stay arm, as with the conventional punched 30 hole stay arm. Hence wear of the friction pad is reduced and the life of the joint is increased. 4 The present invention may also broadly be said 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 the parts, elements or features, and where specific integers are mentioned herein which have known equivalents 5 in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth. BRIEF DESCRIPTION OF THE DRAWINGS Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only and with reference to the 10 accompanying drawings in which; FIG. 1 is a side view of a friction window stay assembly to which the friction window stay of the present invention is applicable; FIG. 2 is a view showing a partial cross-section of the main components of a friction window stay according to the present invention, A showing a cap, B showing a 15 stay arm, C showing a friction pad, D showing an assembled friction window stay, and E showing a frame plate/sash plate; FIG. 3 shows details of a punch and die used in forming a punch hole in the end of the stay arm, together with a partial plan and cross-section view of the stay arm in the vicinity of the punch hole; and 20 FIG. 4 is a partial cross-section showing details of a conventional friction window stay configuration in the vicinity of a pivot point. BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will now be described with reference to the FIG. 1 through FIG. 3. 25 FIG. 1 is a side view of a friction window stay assembly to which the friction window stay of the present invention is applicable. FIG. 2 is a view showing a partial cross-section of the main components of a friction window stay according to the present invention, A showing a cap, B showing a stay arm, C showing a friction pad, D showing an assembled friction window stay, and E showing a frame plate/sash plate. FIG. 3 shows 30 details of a punch and die used in forming a punch hole in the end of the stay arm, together with a partial plan and cross-section view of the stay arm in the vicinity of the punch hole. 5 Components having a similar function to those described before in relation to the conventional friction window stay assembly are denoted by the same reference symbols. As shown in FIG. 1, FIG. 2, and FIG. 3, this friction window stay assembly comprises two friction window stays generally indicated by arrow 1'. Each of these 5 friction window stays ' comprises: a stay arm 20 formed with a hole 22 at one end; a friction pad 24 (cross-section part shown cross-hatched in FIG. 2C and D) formed with a hollow cylindrical protrusion 26 adapted to fit into the hole 22 in the stay arm 20; a frame plate 8 or sash plate 9 formed with a hollow cylindrical protrusion 6 protruding from one side face, adapted to fit into the hollow cylindrical protrusion 26 of the friction pad 24, and 10 a retaining cap 12 for clamping the stay arm 20 to the frame plate 8 or sash plate 9 with the friction pad 24 therebetweeen. A difference with this friction window stay 1' compared to the conventional friction window stay 1 shown in FIG. 4 is that the hole 22 of the stay arm 20 is formed with a rim 28 protruding from one side face of the stay arm 20, and the friction pad 24 is formed with 15 a recess 30 surrounding the protrusion 14 and adapted to accommodate the rim 28 when the protrusion 26 of the friction pad 24 is fitted into the hole 22 in the stay arm 20, with the one side face of the stay arm 20 mating with the side face of the friction pad 24, as shown in the assembled condition in FIG. 2D. With such a construction, the bearing surface area of the pivot attachment is 20 increased by the amount of protrusion of the rim 28 on the stay arm 20. For example as shown in FIG. 2B showing the cross-section of the stay arm 20 in the vicinity of the hole 22, the bearing surface area is increased by the circumference of the hole 22 multiplied by the protruding length L of the rim 28. Moreover, as will be apparent from FIG. 2B and FIG. 3, since the hole 22 is formed so that the metal can flow out to from the rim 28, there 25 is no longer the sharp and rough square edge 18 of the punched hole 4 in the stay arm 2 of the conventional punched hole stay arm 2 shown in FIG. 4. Hence the life of the friction window stay 1' can be considerably increased compared to conventional friction window stay 1, having a plain punched hole or reamed hole in the end of the stay arm 2. Moreover the cost can be reduced compared to a friction window stay having a reamed hole. Also 30 the rigidity is increased in the vicinity of the hole 22, which can be an advantage in the case of a thin stainless steel stay arm 20. 6 FIG. 3 illustrates one method of forming the punched hole 22. In this method, a hole of a smaller diameter than the finished hole (i.e. a smaller diameter than the diameter of the cylindrical protrusion 26 of the friction pad 24) is punched in the end of the stay arm 20 by a conventional method. Then the stay arm 20 with the pre-punched hole is placed 5 over a die 31 with a diameter of the bore 32 larger than the pre-punched hole, and a tapered punch 33 with an appropriate maximum diameter (i.e. the diameter of the cylindrical protrusion 26 of the friction pad 24) is then punched into the pre-punched hole, to form the final hole 22 with the rim 28 protruding from one side face of the stay arm 20. Alternatively depending on manufacturing procedures, it may be possible to form 10 the hole 22 in the stay arm 20, in a single process by having a sharp edge on the tip of the punch to punch out a blank for the hole, rather than forming the initial hole by a pre-punch process. Assembly of the components to produce the final friction window stay I' is by the same procedure as described before in the background art section for the conventional 15 friction window stay 1, but with the rim 28 of the stay arm 20 fitting into the recess 30 of the friction pad 24. We believe the advantages of our invention to be as follows, however it should be appreciated that all such advantages may not be realised'on all embodiments of the invention and the following list is given by way of example only as being indicative of 20 potential advantages of the present invention. Furthermore it is not intended that the advantages of the present invention be restricted to those of the list which follows: 1. By providing the rim part on the stay arm, the bearing surface area of the pivot attachment is increased, thereby reducing the load on the bearing surfaces and increasing the life of the stay arm. 25 2. By forming the rim part by a punching operation so that the rim is plastically deformed, there is no longer the sharp and rough square edge, and hence no need to ream the hole to remove the sharp and rough edges. 3. By providing the rim protruding from one side, the overall rigidity of the stay arm can be increased which is advantageous in the case of a thin stainless steel stay arm. 30 Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope of the invention as defined in the appended claims. 7

Claims

1. A friction window stay for supporting and holding an openable window in an optional opened position, comprising: a stay arm formed with a hole at one end; 5 a friction pad formed with a hollow cylindrical protrusion protruding from one side face, adapted to fit into said hole of said stay arm; a frame plate/sash plate formed with a hollow cylindrical protrusion protruding from one side face, adapted to fit into said hollow cylindrical protrusion of said friction pad; and 10 a retaining cap for clamping said stay arm to said frame plate/sash plate with said friction pad therebetweeen, wherein said hole of said stay arm is formed with a rim protruding from one side face of said stay arm, in a shape substantially the same as one formed by punching a hole of a smaller diameter than a diameter of said cylindrical protrusion of said friction pad in the 15 end of said stay arm, and then punching with a tapered punch to form a final hole with said rim protruding from one side face such that a bearing surface area of said hole is increased by said hole's circumference multiplied by said rim's protruding length, and said friction pad is formed with a recess surrounding said hollow cylindrical protrusion on said one side face, adapted to accommodate said rim when said protrusion of said friction pad is fitted 20 into said hole of said stay arm, with said one side face of said stay arm mating with said one side face of said friction pad.

2. A friction window stay assembly comprising a friction window stay according to claim 1.

3. A method of manufacturing a friction window stay comprising the steps of: 25 producing a stay arm by deforming a hole in an end of an elongate metal plate using a punch such that a rim is formed on a punch exit side of the hole, and a bearing surface area of said hole is increased by said hole's circumference multiplied by said rim's protruding length; producing a friction pad in the form of a flat member with a hollow cylindrical 30 protrusion on one side thereof, which is adapted to fit into said hole of said stay arm, and 8 which is formed with a recess surrounding said hollow cylindrical protrusion adapted to accommodate said rim of said stay arm; producing a frame plate/sash plate with a hollow cylindrical protrusion protruding from one side face, adapted to fit into said hollow cylindrical protrusion of said friction 5 pad; and clamping said friction pad between said stay arm and said frame plate/sash plate with said rim of said stay arm accommodated in said recess of said friction pad, and securing in this condition with a retaining cap.

4. A method of manufacturing a friction window stay according to claim 3, wherein 10 said rim protruding from one side face of said stay arm is formed by punching a hole of a smaller diameter than a diameter of said hollow cylindrical protrusion of said friction pad in the end of said stay arm, and then punching with a tapered punch to form a final hole with said rim protruding from one side face.

5. A method of increasing bearing surface area of a pivot joint of a friction window 15 stay comprising the steps of: deforming a hole in an end of an elongate metal plate constituting a stay arm of said friction window stay using a punch such that a rim is formed on a punch exit side of said hole, and the bearing surface area is increased by said hole's circumference multiplied by said rim's protruding length; and 20 forming a recess in a friction pad of said friction window stay to accommodate said rim.

6. A friction window stay substantially as described herein and with reference to figure 1 through figure 3.

7. A method of manufacturing a friction window stay substantially as described herein 25 and with reference to figure 1 through figure 3. 30 M. J. SERVICE & ASSOCIATES Attorneys for: Aluminium Systems NZ Limited 9