NZ230905A - Pivot bearing includes wear resistant insert - Google Patents

Description

2309 05 i >■ ■ Cu:r.; U- ©"vW,.©^, i I' P'„ t'l.a'.i^n rNj,. 2 5 NOV 1993 «^:v No: Date: NEW ZEALAND Patents Act 1953 CQMPLETS SPECIFICATION A PIVQT BEABINS We, INTERLOCK INDUSTIRES LIMITED, a New Zealand Company of Portsmouth Road, Miraraar Wellington, New Zealand do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement -l-(Followed by la) •V \ * OCT1989*// \ A // - i i - 230905 This invention relates to a pivot bearing and in particular to a pivot bearing formed in a window stay or between a component of a window stay and an in-situ frame.

The adjustable mounting of a window sash in a window frame is conventionally carried out by using a pair of window stays. These stays can be so located that the sash operates as a casement or awning window. For correctness of operation of the window, especially where "pull-in" is concerned, the stays must be so constructed that they have the same geometry and thus effectively operate as a matched pair. To achieve correctness in geometry the pivot bearings must be accurately formed and clearly therefore the centres of the pivot bearings must be correctly located. If the pivot centres are not consistently positioned then differing geometry of stays will result and uniformity between stays will be lost.

As the pivot bearing in a modern window stay usually operates as a friction bearing it is also important to achieve consistent levels of friction in the bearings. The level of friction is normally established by the pressure within the bearing caused by the bearing fastening. Modern window designs can, however, place high demands on friction bearings due to large loadings caused by sashes which are heavy due to their physical size or the amount of glass being carried therein. In addition to holding the bearing components together and providing the friction pressure within the bearing the bearing fastening must also be able to withstand high shear forces created within the bearing. Design problems can consequently arise if there are physical restraints on the size of the fastening due to the requirement of compactness of stay dimensions, compactness of bearing or other factors. The restraints on size often arise from the need for a compact 2 230905 stay to fit within the cavity between the window sash and frame.

In our New Zealand Patent Specification 202214/202755 it is therefore proposed that the pivot bearing be formed by a spigot, drawn from the parent metal, of one component to be positioned within an opening in a second component and the free end of the spigot rolled over to couple the two components together such that axial movement apart is not possible. The spigot thus not only accurately defined the centre of the bearing but also increased the load carrying capacity of the pivot bearing.

Subsequently it was proposed in New Zealand Patent Specification 212534 that rather than roll over the end of the spigot to fasten the two components together a separate fastener be used. This fastener had the free end of the body thereof crimped under in the bore mouth of the spigot.

The object of the present invention is to provide an improved or modified form of pivot bearing.

Broadly in one aspect the invention provides a pivot bearing between first and second members the first member incorporating an annular wall extending from one face thereof said wall defining the periphery of an aperture through said first member to a second face thereof, a second member incorporating an opening therein, said wall being located within said opening, a fastening located within the aperture and having means to prevent axial movement of the fastening to thereby retain the assembly together, said means being located in the mouth of said aperture at said second face, said mouth comprising a recess formed in the second face, there being wear resistant self lubricating material within the pivot 3 230 S 05 bearing to prevent said second member contacting said first member, wall and fastening.

In the following more detailed description of a preferred form of the pivot bearing according to the invention reference will be made to the accompanying drawings in which Figure 1 is a cross-sectional elevation of the pivot bearing according to one form of the invention, Figure 2 is a cross-sectional elevation of a second form of bearing according to the invention and Figure 3 is a detail view of a modification in the area where the crimped over end of the fastener engages with the surface of a third component such as the sash or frame of a window.

The pivot bearing according to the invention is designed to preferably provide a friction bearing between two components. The bearing is primarily intended for use in a window stay and thus the two components can be a pair of arms or a mounting plate and an arm. in accordance with known window stay construction the components can be formed from stainless steel or an aluminium alloy. The present pivot bearing is particularly suited for construction from stainless steel as the components are not dependent on thickness for strength. Accordingly a compact but strong pivot joint can be achieved using the present invention.

Referring firstly to Figure 1 the two components are respectively shown at 10 and 11. First component 10, which can be an arm, has an opening 12 formed therein. Likewise second component 11, which can be a mounting plate, has formed therewith a hollow cylindrical projecting portion 14 (hereinafter simply referred to as an "upstand") which defines a bore 13. It is preferred that this upstand 14 be formed integrally with component 11 by being drawn fron the parent netal. The upstand for all bearings on a plate or arm can be formed at the same time in a tool suitable for the purpose thereby ensuring accurate control of distance between centres.

The other components of the bearing consist of the bearing fastening 15 and an insert. The insert is preferably formed of a self-lubricating wear-resistant plastics material such as nylon. The insert 16a in the form illustrated in Figures 1 to 3 consists of a sleeve 17 which has at one end thereof an integrally formed flange 18. As shown flange 18 can be of greater or varying thickness as a result of suitable profiling thereof. The other part of the insert is a separate rimmed washer 16b. In other forms the insert can be formed in a variety of ways such as two washers and a separate sleeve or with a flanged sleeve and a separate rimmed washer at either 16a or 16b.

The bearing fastening 15 consists of a body 19 and a head or flange 20 at one end thereof. The fastening 25 is preferably a screw or the like.

To assemble the pivot bearing insert 16a can be placed on the upstand 14 or in the opening 12 of component 10. The two components 10 and 11 are brought together so that the upstand 14 is located within opening 12 but metal to metal contact is avoided due to the presence of sleeve 17. The fastening 15 is then introduced into bore 13 of upstand 14 (rimmed washer 16b having firstly been put in position) and the free end swaged, crimped or otherwise deformed so as to be enlarged in the mouth of bore 13 and thereby prevent axial movement of the fastening relative to upstand 14. In the completed joint there is, because of inserts 16a and 16b, no metal to metal contact between 230 9 05 fastening 15 and first component 10 nor between first component 10 and upstand 14.

The level of friction within the joint is established by the level of pressure in the joint caused by the fastening 15. As illustrated the fastening 15 is preferably provided with a large diameter head 20 so that a large area of nylon can be captured between the head and the surface of component 10. An equally large area of nylon formed by flange 18 exists between the interfacing surfaces of components 10 and 11. These areas of nylon and the large area of head 20 means that the nylon does not need to be under high pressure by the fastening 15 in order to achieve a required level of static friction. There is, however, a high level of dynamic friction achieved by such an arrangement and this dynamic friction results in a level of friction which controls any rapid movement of the window. This dynamic friction therefore prevents the window from slamming shut in windy conditions. In addition the dynamic friction which can be achieved results in smooth operation of the window once the static friction has been overcome during opening or closing of the window.

In a window stay application the second component 11 would usually form a fixed component such as a frame or sash mounting plate. The first component 10 would thus be a movable arm. As a consequence fastening 15 is removed from any load carrying forces, especially shear forces, as a result of the presence of the annular upstand 14. As mentioned previously the accuracy of the centre of the pivot does not depend on the fastening 15 as this is established by the integrally formed annular upstand 14. The function of the fastening 15 is thus to secure the components together and also to establish the pressure 6 23 0 a o 5 within the joint which, in accordance with known techniques, determines the friction level.

As shown the fastening 15 is hollow and this permits a fastener 25, e.g. a screw, to pass through the bearing and into the frame or sash 26 of the window. This not only obviates the need to have separate screw holes in mounting plate 11 but the presence of the screw in the bearing assists transfer of loads to the sash/frame 26 from arm 10.

As shown, a recess 29 is formed in the transition or mouth area 27 so as to not only accommodate the crimped over free end of fastening 15 but also to enable such crimped over end to effectively be located or sandwiched between the mounting plate 11 and sash/frame 26. This recess 29 can be formed in a number of ways two examples of which are shown. In Figure 1 a "punch and dimple" type method displaces metal about the upstand 14 to form the recess 29 and a projection 30. According to the arrangement in Figure 2, however, the area of metal about the upstand 14 is displaced in an inclined manner to recess 29.

By having recess 29 a large "flange" 31 can be formed by the crimping of the free end of fastening 15 and this enables large loadings in the bearing to be withstood. Consequently the bearing is capable of carrying higher loads in a direction perpendicular to the plane of the arm, i.e. prising off loadings.

Additionally, the metal thickness in fastening 15 and in upstand 14 change smoothly from the original material thickness to that at the places where the most deformation has had to occur when forming the respective parts into their final configuration. 7 230905 The axial load exerted by a fastener 25 properly tightened will be directly reacted into the frane/sash 26 due to the fastening 15 "seating" with or onto the frame/sash 26. In an alternative arrangement the bottom edge of the fastening 15 can be serrated (as at 33 in Figure 3) for increased grip with the sash/frame 26 to hold the bearing firmly in position with increased load carrying capacity. Also the serration can assist in prevention of the fastening 15 rotating under the final torque tightening of screw 25. The frame/sash 26 can likewise be serrated as at 34.

The configuration of bearing is capable of providing, when required, a very low friction bearing which still has a very good load carrying capacity. This is achievable due to the flange 31 in recess 29 being formed flush with surface 27 so that when the fastener 25 is tightened it does not cause fastening 15 to move axially and thus result in excessive or increased friction in the bearing. However, by controlling the "degree of flustiness" it may be possible to provide an effective means of varying the level of friction in the bearing. 8 •'1 i a

Claims (10)

WHAT WE CLAIM IS:-

1. A pivot bearing between first and second members the first member incorporating an annular wall extending from one face thereof said wall defining the periphery of an aperture through said first member to a second face thereof, a second member incorporating an opening therein, said wall being located within said opening, and a fastening located within the aperture and having means to prevent axial movement of the fastening to thereby retain the pivot bearing assembly together, said means being located in the mouth of said aperture at said second face, said mouth comprising a recess formed in said second face, there being wear resistant self lubricating material within the pivot bearing to prevent said second member contacting said first member, wall and fastening.

2. The pivot bearing of Claim 1 wherein the fastening comprises a body of tubular or hollow construction, said body having a flange or head located at one end thereof.

3. The pivot bearing of Claim 2 wherein the wear resistant self lubricating material is formed as a sleeve which is located between said wall and said fastening, there being a flange extending from one end of said sleeve and located between said first and second members the head or flange of the fastening being separated from the second member by a washer formed of said wear resistant self lubricating material.

4. The pivot bearing of any one of the preceding Claims wherein the recess is such that, when the first member is located on a surface, the radially expanded portion of the fastening in the recess is located or sandwiched between the first member and the said surfacl^v // ^ ' o *;i;2 0 MAY 1992 m;/;r ^;9;

5. The pivot bearing of any one of Claims 1 to 4 wherein the recess is formed by an inclined transition between said first member and the annular wall.;

6. The pivot bearing of any one of Claims 1 to 4 wherein the recess is formed by a displacement of material of the first member.;

7. The pivot bearing of Claim 4 wherein one or both of the radially expanded portion of the fastening and said surface is provided with grip enhancing means.;

8. A pivot bearing substantially as herein described with reference to Figure 1 or 2 and 3 of the accompanying drawings.;

9. A window stay including at least one pivot bearing as claimed in any one of Claims 1 to 7, said first member being a mounting plate and said second member being an arm.;

10. The window stay of Claim 9 further including a fastener engaged through said fastening of the pivot bearing.;INTERLOCK INDUSTRIES LIMITED By its Attorney;Don Hopkins;Registered Patent Attorney;20MM1992S;' .*S -V ' A