GB2101203A - Improvements in friction stays for windows - Google Patents

Abstract

In a rivetted friction stay for windows, the pivot joint for high performance and simplified assembly includes a plastics coated rivet 8 with a frustoconical head 13 that seats in complementary recess 17 concentric to a hole 16 in a stay arm 6. The stay arm 6 is pivotally connected to a mounting plate 1 by the rivet with the arm 6 and plate 1 being separated by a spacer 9 comprising a support plate 11 and a washer 10. The tail of the rivet is clinched to the underside of the plate 1 to generate the desired friction in the joint and a spiked washer 12 is disposed under the tail on clinching to prevent the rivet rotating relative to the plate 1. Various embodiments of stays with pivot joints are described with different arrangements of spacer and location for the rivet tail. <IMAGE>

Description

SPECIFICATION Improvements in friction stays for windows This invention concerns improvements in friction stays for windows or the like.

Such friction stays are designed and arranged to mount a sash (as hereinafter defined) on a fixed frame for adjustable movement of the sash relative to the frame.

The term "sash" as used herein means a closure member adjustable relative to a frame and arranged to close an aperture in the frame. The term "sash" is deemed to include a glazed light for top, bottom or side opening, or a non-glazed or partly glazed member such as a fan-light, door or casement.

Various kinds of stays are already known in which arms or links and mounting plates or brackets are connected together by pivot joints.

The arms or links extend between the sash and the frame to which they are pivotally connected by the mounting plates or brackets, and a sash is supported on each of two opposed sides by a respective stay. The arrangement of the stays is such that the stays fold up and are confined within a rebate between the sash and the frame when the sash is closed, and for opening and closing movement of the sash, the stays act as hinges with the arms or links pivotting relative to the plates or brackets. The links may comprise two or more elements pivotted together, and the stay may comprise more than one set of arms or links.

In use the sash cannot be permitted to pivot freely on such stays, and some form of restraint is provided, and this invention is particularít concerned with friction stays wherein the frictional restraint is provided by rivetted pivot joints in which the rivet is clinched under pressure to hold the stay parts tightly together for controlled pivotal movement with designed frictional resistance.

These rivetted friction pivot joints are not as simple and easy to manufacture as may be expected, and there are substantial problems arising both in mass manufacture and in subsequent installation and use in service.

Particular problems arise in manufacture from the need to maintain tight tolerances for the rivet centres, special control of the materials used, and precision in the rivetting operation to achieve and maintain the requisite tension in the rivet following clinching.

Problems in use of such rivetted friction stays arise from the loads which have to be supported by the stay, such as the glazed weight of the sash and substantial wind loads arising when the stay is extended carrying the sash. There are also the abusive conditions which the stay has to withstand in service, such as weathering, movement of the sash or frame and lack of maintenance. A special problem stems from the corrosion or weathering and wear in the rivetted pivot joints for one condition may excite or promote the other.

These rivetted friction stays have to be designed to a wide range of specifications, this being necessary to accommodate different dimensions, weights, applications, materials and service conditions as well as customer preferences. This leads to further critical requirements have have to be satisfied by the performance of each rivetted friction pivot joint in the stay.

It is an object of this invention to provide an improvement in friction stays having rivetted friction pivot joints whereby the rivetted joint is of simple form facilitating precision in manufacture of the stays.

Another object of the invention is to provide a rivetted friction stay wherein the rivet joints are neat and compact.

A further object of this invention is to provide a rivetted friction stay in which the rivetted pivot joint is resistant to wear and is designed to uniformly distribute the load.

Further objects of this invention include providing an improved pivot joint which can be easily assembled and clinched in the mass manufacture of rivetted friction stays, and providing particular arrangements of rivetted friction stays for special applications or uses.

According to this invention, we provide a rivetted friction stay having first and second elements pivotally connected together by a rivet, a spacer is disposed between said first and second elements to space said elements apart for relative movement, the rivet extends through both of said elements and the spacer, the head and shank of the rivet is coated with a plastics material providing low friction surfaces on the rivet, the head of the rivet is of frusto-conical form received for relative pivotal movement in a complementary recess in that face of the first element having an oversize clearance hole concentric with the recess through which hole the shank of the river extends with radial clearance, the tail of the rivet is clinched under pressure on that face of the second element remote from the spacer and the tail is located to prevent rotation of the rivet relative to said element.

With this invention, by providing the frustoconical head on the rivet and the complementary recess in the first stay element a substantial load bearing area for uniformly distributing loads is provided. This load bearing area is one of the critical factors for obtaining optimum performance. Previously it has been the standard practice to use flat headed rivets which, size for size, provide a bearing area of about 20% less.

Furthermore, by the provision of the frustoconical head and complementary recess, on assembly of the joint, and the joint itself is selfcentering which avoids many of the difficulties in prior forms of pivotal rivetted joints wherein the flat headed rivet has to be accurately located in the respective stay element. It is also considered that the strength of the rivet where it is subject to high shear in service is greater with a frustoconical head than with a flat head, particularly at the juncture of the head and the shank where the rivetted joint is subject to twisting and/or bending loads.

Additionally, by providing the plastics coating on the rivet, metal to metal contact between the head of the rivet engaging the recess face of the first element is avoided without any necessity to provide any intervening low friction washer which, if it was used, would lead to a number of problems such as changing of the designed frictional restraint in service due to creep or deformation of the washer material.

The coating on the rivet also permits the selection of different metals for the stay elements and the rivet and avoids problems of corrosion between dissimilar metals at interfaces.

The firs stay element is provided with an oversize clearance hole through which the rivet shank extends with adequate clearance both to permit the afore-mentioned self-centering and to prevent the plastics coating on the rivet shank being damaged by the edge of the hole.

This invention may be applied to friction stays having stay elements of aluminium or steel, and these elements may be given suitable surface treatments for corrosion resistance and/or visual enhancement.

Preferably, the spacer interposed between the first and second elements has a low friction surface for sliding supporting engagement of the first element on pivotal movement of said first element.

By providing a low friction surface, wear is avoided and on pivotal movement a support face is provided immediately adjacent the rivet shank to reduce the bending and shear forces applied to the shank on opening and closing movement of the stay.

Conveniently, the spacer comprises an annular washer. The washer may be of metal coated with a plastics material.

In a preferred arrangement, the spacer comprises a plate seated on the second element and having a recess in which the washer is received.

The plate is arranged to provide a substantial load supporting surface and the plate overlies the second element. The plate is preferably of a low friction plastics material and may have means for locating it against movement relative to the second element. The plate is secured in situ during the clinching of the rivet and as well as providing the support face it provides a reinforcement to the second element to preclude deformation of the second element by the clinching pressure. For certain applications of friction stay, the plate comprises a stop face for abutment by the first element to limit pivotal movement thereof.

By such an arrangement, the pivotal movement of the stay is limited in a simple expeditious manner incorporated in the pivit joint during assembly of the stay.

The clinching pressure applied to the rivet is sufficient to provide the desired friction restraint within the joint in known manner for the particular friction stay and the specification of service therefor. Traditional methods of clinching may be employed such as rolling or turning as appropriate to the particular type and material of rivet.

Accordingly to another aspect of this invention, the second element is provided with a frustoconical recess into which the underside of a frusto-conical plunge in the first element may be received with the spacer of frusto-conical form being interposed therebetween.

Preferably such an arrangement is applied to a friction stay wherein the elements are made of steel where the oversize clearance hole in the first element can be formed by a plunge and piercing operation with a similar manufacturing technique being employed for the second stay element.

The tail of the rivet is prevented from rotating relative to the second stay element, and this may be achieved in several ways.

In a preferred arrangement the second element is provided with formations into which the tail of the rivet is clinched. The formations may comprise a series of ribs or splines in the underside of the second element, or teeth or radial serrations formed in the marginal edge of the hole in the second element through which the tail of the rivet extends.

By such arrangements of formations, the ribs or splines or teeth provide discrete projections about or on which the tail of the rivet is clinched so as to hold the mass of the clinched tail against rotation.

The ribs or splines may be an integral feature of an extrusion used for the second element and provide the additional advantage of strengthening the second element. The radial serrations or teeth on the marginal edge of the hole may be formed simply in the piercing operation when the hole is formed.

In an alternative arrangement, the tail of the rivet may be located relative to the second element by interposing a spiked washer under the tail so that on clinching pressure being applied, the spikes bite into the second element and locate it whilst the tail is forced into and between the spikes to secure the tail to the spiked washer.

This invention is deemed to include various configurations of rivetted friction stays but has special application to friction stays having two mounting plates adapted respectively for securing to a fixed frame and a sash, and two arms one being longer than the other. In such a stay, each of the opposed ends of the two arms is pivotally connected to a respective mounting plate with the pivotal connections being rivetted joints as aforementioned. However, in other applications of this invention, the first and second elements may be constituted by any combination of stay parts, for instance, an arm and a plate, two link parts, a plate and a link, a bracket and an arm, or the reverse of any of same.

The invention will now be described in further detail with reference to exemplary embodiments depicted in the accompanying drawings wherein: FIGURE 1 is a side elevation of a first embodiment of a rivetted friction stay shown in an open position; FIGURE 2 is a sectional view on line Il-Il of Figure 1 showing a rivetted pivot joint; and FIGURE 3 is an exploded perspective view of the assembly of the rivetted pivot joint depicted in Figure 2.

FIGURE4 is an exploded perspective view of the assembly of a rivetted pivot joint of a second embodiment; FIGURES is a sectional view of the clinched rivetted pivot joint of Figure 4; and FIGURE 6 is an underneath plan view of the rivetted pivot joint of Figure 5.

FIGURE 7 is an exploded perspective view of the assembly of a rivetted pivot joint being a modification to the second embodiment; and FIGURE 8 is a sectional view of the clinched rivetted pivot joint of Figure 7.

FIGURES 9, 10 and 11 depict a third embodiment with the views of Figures 9 and 10 being similar to those of Figures 4 and 5, with Figure 11 being a top plan view of the rivetted pivot joint.

FIGURE 12 is a side elevation of a fourth embodiment of a friction stay shown in the open position.

With reference to the first embodiment shown in Figures 1, 2 and 3, the friction stay comprises a first mounting plate 1 having spaced apart holes 2 through which the plate 1 may be secured to the fixed frame of a window (not shown) by suitable screws or similar fasteners (not shown). The plate 1 is rectangular of L-section and is an extrusion of aluminium alloy which may be anodised.

The friction stay further comprises a second rectangular mounting plate 3 similar to the first mounting plate 1 being an L-section aluminium extrusion. The second mounting plate 3 also has spaced apart holes 4 through which the plate 3 may be secured to a sash of a window (not shown) by suitable screws or fasteners (not shown).

The first and second mounting plates 1, 3 are coupled together by a first arm 5 and a longer second arm 6. The arms 5, 6 are of substantially rectangular section with radiused ends and are also aluminium alloy extrusions. The ends of each arm are pivotally mounted and connected to a respective mounting plate by rivetted friction pivot joints generally designated by reference 7. The pivot joints 7 permit the mounting plates 1, 3 to fulfil a hingeing movement relative to each other controlled by the respective lengths of the arms 5, 6 and the centres of the pivot joints.

In known manner, in a window two such friction stays are used to support a sash for opening and closing movement relative to the fixed frame. For a top hung window, for which the stay of this first embodiment is suitable, the friction stays are mounted one on each side of the frame and the sash. In the open position of the stays as shown in Figure 1, the stays support the sash projecting outwardly from the frame. When the sash is closed to the frame, the arms fold upwards from the position shown in Figure 1 and lie between the overlying mounting plates 1, 3 with the folded stay being confined within a rebate extending between the frame and the sash.

The pivot joints 7 connecting the ends of arms 5 and 6 to the mounting plate 1 are the same and the assembly comprises a rivet 8, a spacer 9 comprising an annular washer 10 and a support plate 11, and a spiked location washer 12.

The river 8 has a metal body with a frustoconical head 13 and a cylindrical shank 14. The rivet head and shank have a coating 1 5 of plastics material such as nylon applied by powder coating followed by thermal or other bonding treatment.

The coating 1 5 is firmly bonded to the metal surfaces of the rivet and provides an integral low friction surface as well as a protective layer on the rivet.

Each end of the arms 5, 6 is provided with a through hole 1 6 and the outer face of the arm is formed with a frusto-conical recess 17 concentric with the hole 1 6 and complementary to the frustoconical head 1 3 of the rivet. The hole 1 6 is oversize with respect to the diameter of the rivet shank 14 so that an annular clearance is provided between the rivet shank and the marginal edge bounding the hole when the rivet is assembled as shown in Figure 2. The clearance is sufficient to prevent the marginal edge face bounding the hole 1 6 from rubbing or abrading the coating 1 5 on the rivet shank during assembly and use in service.

Furthermore, the clearance is also sufficient to provide a tolerance for accurate centering of the rivet during assembly.

For each pivot joint 7, the mounting plate 1 is also formed with a hole 8 pierced and plunged through the plate to provide a rebate 1 9 on the underside of the plate. The centres of the holes 18 are accurately spaced along the length of the mounting plate 1 for the designed pivotal and hingeing movement of the arms 5, 6.

The end of each arm is connected to the mounting plate 1 by a rivet 8 and the spacer 9 separates the opposed metal surfaces of the arm and the plate to prevent metal to metal contact.

The annular washer 10 is received in a complementary hole in the support plate 11 to locate the washer 10. The washer 10 is preferably a plastics coated metal washer or a plastics washer. The support plate 11 is flat and of rectangular dimensions to lie wholly under the end portion of the arm around the pivot joint. One side of the plate 11 abuts against the upstanding edge flange 20 of the mounting plate 1 to prevent the plate 11 rotating on pivotal movement of the arm.

The support plate 11 is of low-friction plastics material such as an acetal resin.

As best shown in Figure 2, in the pivot joint 7 the faces of the support plate 11 and the washer 10 provide opposed thrust faces for load transmission and on pivotal movement of the arm relative to the plate 1, the end of the arm is supported for sliding bearing engagement over a significantly large area adjacent the pivot axis.

In the assembly of the pivot joint, the shank of the rivet extends through the hole 1 8 in the mounting plate 1 and projects into the underside recess 1 9 with the spiked washer 1 2 being received on the end of the shank.

To rivet the assembly together the tail 21 of the rivet is clinched under a predetermined load so that the rivet is maintained in tension to a required and designed degree to impart a frictional resistance within the pivot joint. The tail 21 is clinched under load by rolling or turning, and on such clinching the spiked washer 1 2 is caused to bite into the underside of the plate 1 and the material of the tail is pressed onto the washer 12.

The washer 12 thereby locates the rivet against rotation relative to the mounting plate 1 and the clinched tail is seated and confined within the recess 19. Under the clinching pressure some local deformation of the support plate 11 occurs but this is accommodated in the design.

As will now be appreciated, the pivot joint is such that only the arm can pivot with respect to the mounting plate for the rivet is located against turning. On pivotal movement of the arm, the bearing forces are transmitted through the frustoconical faces of the rivet head 1 3 and the recess 1 7 with the additional support provided by the spacer 9. The residual tension in the rivet provides the frictional restraint required in the pivot joint.

In this stay of the first embodiment, the pivot joints 7 connecting the other ends of the arms 5 and 6 to the sash mounting plate 3 are similar but the spacer 9 is a flat annular washer 22 similar to washer 10 but of greater external diameter. If desired, the spacer 9 at these pivot joints may include a flat support plate as aforedescribed.

The other embodiments of this invention will now be described with reference to the relevant Figures of the drawings wherein the same references as given for the first embodiment are used to designate similar parts. The following description is directed to the essential differences between the first embodiment and the other embodiments.

With reference to the second embodiment illustrated in Figures 4, 5 and 6, there is shown a pivot joint 7 suitable for a friction stay similar to the first embodiment. The pivot joint comprises a rivet 8, a spacer 9 comprising a washer 10 and support plate 11. The mounting plate 1 is of flanged channel section providing on the underside a wide groove 23. The base of the groove 23 is formed with longitudinal ribs or splines 24. The mounting plate 1 is an aluminium extrusion with the ribs or splines 24 being integrally formed on extrusion.

On clinching of the rivet tail 21, the rivet material is deformed into the ribs or splines 24 and this prevents rotation of the rivet 8 relative to the mounting plate 1. To locate the support plate 11 of the spacer 9 on the mounting plate 1 , the support plate 11 has opposed flanges 25 on the underside which complement the edge flanges 26 of the mounting plate 1. The arrangement of the flanges 25 with the mounting plate 1 prevent the support plate 11 turning on pivotal movement of the arm 6.

With reference to the modification of the second embodiment depicted in Figures 7 and 8, the spacer 9 comprises a flat annular washer 27 of metal coated with a plastics material or of a plastics material. In this modification the support plate of the spacer is omitted and such a pivot joint is suitable for short small friction stays with relatively low weight carrying capacity in service.

With reference to the third embodiment depicted in Figures 9, 10 and 1 this is designed for the manufacture of rivetted friction stays with the mounting plates and arms of stainless steel or coated steel wherein smaller sectional material may be employed to give the same load carrying capacity as aluminium materials. Only part of the stay is shown being the arm 6 and the mounting plate 1. The mounting plate 1 is of channel section providing on the underside a groove 28 extending lengthwise of the plate. A piercing 1 8 is plunged in the central portion of the plate 1 so as to provide a frusto-conical recess 29 surrounding the piercing.The marginal edge of the piercing is formed with teeth or serrations 30 (as best seen in Figure 9) and the tail 21 of the rivet 8 is clinched into these teeth to prevent the rivet from rotating relative to the mounting plate 1.

The arm 6 is cranked or joggled adjacent the end which is radiused and provided with the oversize hole 1 6 that is also pierced and plunged to provide a frusto-conical recess 1 7 complementary to the frusto-conical head 1 3 of the plastics coated rivet 8.

Intermediate the arm 6 and the plate 1 there is a spacer 9 constituted by a washer 31 through which the shank of the rivet extends. The washer is of low friction material or has a low friction surface and has a special part-conical form similar to the type of washer known as Belleville. The cone angle of the washer 31 corresponds to that of the opposed faces of the arm and the plate to ensure adequate thrust and load bearing surfaces.

As in the other embodiments, the rivet is clinched to ensure a residual frictional force in the pivot joint and the arm is pivotally connected to the mounting plate by the rivet. The thrust and load transmitting faces are substantial for supporting the high loads, and in this embodiment the arm is also located relative to the mounting plate by the provision of the two complementary plunges in the arm and mounting plate which engage each other.

With reference to Figure 12, this depicts a rivetted friction stay suitable for high weight carrying capacity in service and it has particular application for sashes to be side hung in a frame with the sash opening sideways about a vertical hingeing axis.

As previously described with reference to Figure 1, the stay comprises mounting plates 1, 3 and two arms 5, 6 which are pivotally connected together by rivetted pivot joints 7. The rivetted pivot joints 7 connecting the arms 5, 6 to the sash mounting plate 3 and the joint 7 connecting the arm 6 to the frame mounting plate 1 are substantially the same as described in the first embodiment. The essential difference is the provision of a special support and stop plate 32 forming part of the spacer.

The support and stop plate 32 is rectangular in plan view and includes an arcuate support rib 33 of which the face is in supporting engagement with the arm 5. The plate 32 also has an upstanding pad 34 of which one side is arranged to provide a stop face 35 to limit the extent of pivotal movement of the arm 5. Additionally, the plate 32 provides a further support face 36 which, on folding movement of the longer arm 6 provide a support for the underside of the arm 6.

Preferably, the support and stop plate 32 is a plastics moulding secured to the mounting plate 1 by screws or like fasteners (not shown) extending through holes 37 provided in the plate 32.

It will now be appreciated that the friction pivot joint in the friction stay is compact and of simple form with the frusto-conical faces of the rivet head and the recess in the arm providing the substantial areas for load transmitting engagement not only for rotation but also for the tensile loads.

Furthermore, due to the over-size hole in the arm, and the use of the frusto-conical faces, on assembly and clinching, the rivet is self-centering to align correctly despite any manufacturing tolerances within specified limits. In particular, variations arise in the overall dimensions of the rivet due to the plastics coating thereon.

The use of a frusto-conical head recessed in the arm permits the design of a compact neat joint if the head is arranged to be flush with the upper surface of the arm. This is in contra-distinction to other forms of rivetted joints where a flat rivet head stands proud on the arm or has to be seated in a special counterbore reducing the overall thickness of the arm over a substantial part where strength is required.

It should be noted that only exemplary forms of stay including the improved rivetted friction joint have been described herein. Other forms of friction stays can have such friction pivot joints.

The mounting plate and the arm may be of suitable configuration and/or section to suit the particular application or design requirement such as may be dependent on or dictated by the type of window system with which the stay is to be employed.

Claims (12)

1. A rivetted friction stay having first and second elements pivotally connected together by a rivet, a spacer is disposed between said first and second elements to space said elements apart for relative movement, the rivet extends through both of said elements and the spacer, the head and shank of the rivet are coated with a plastics material providing low friction surfaces on the rivet, the head of the rivet is of frusto-conical form received for relative pivotal movement in a complementary recess in that face of the first element having an oversize clearance hole concentric with the recess through which hole the shank of the rivet extends with radial clearance, the tail of the rivet is clinched under pressure on that face of the second element remote from the spacer and the tail is located to prevent rotation of the rivet relative to said element.

2. The friction stay according to claim 1 wherein the spacer has a low friction surface for sliding supporting engagement of the first element on pivotal movement of said first element.

3. The friction stay according to claim 2 wherein the spacer comprises an annular washer.

4. The friction stay according to claim 2 wherein the spacer comprises a plate seated on the second element and having a recess in which the washer is received.

5. The friction stay according to claim 4 wherein said plate comprises a stop face for abutment by the first element to limit pivotal movement thereof.

6. The friction stay according to claim 1 wherein the second element is provided with a frusto-conical recess into which the underside of a frusto-conical plunge in the first element is received with the spacer of frusto-conical form being interposed therebetween.

7. The friction stay according to any one of the preceding claims wherein the second element is provided with formations into which the tail of the rivet is clinched.

8. The friction stay according to claim 7 wherein the formations comprise a series of ribs or splines in the underside of the second element.

9. The friction stay according to claim 7 wherein teeth or radial serrations are formed in the marginal edge of the hole in the second element through which the tail of the rivet extends.

10. The friction stay according to any one of the preceding claims wherein the first element comprises a first arm and the second element comprises a mounting plate adapted for securing to a fixed frame of a window.

1 The friction stay according to claim 10 further comprising a second arm longer than said first arm and a second mounting plate adapted for securing to a sash, each of the opposed ends of the first and second arms being pivotally connected to a respective mounting plate.

12. The friction stay substantially as hereinbefore described with reference to any one of the embodiments depicted in the accompanying drawings.