IE51747B1 - Improvements in friction stays - Google Patents

Abstract

The invention relates to a friction support for windows or the like, with a mounting plate (3) and an arm or joint member (1) for connection to a fixed frame or to a window wing. The plate (3) and the joint member (1) are pivotably connected via a joint in a friction-inhibited manner. The pivot joint consists of a rivet (10) which extends through punched holes or bores (11 and 12) in the joint member and the plate. The rear end of the rivet is riveted on the underside of the plate, in order to generate the necessary permanent pressure for frictional inhibition. Arranged under the head of the rivet is a plastic-coated washer (14) which rests merely on the essentially flat and unlimited surface of the end (2) of the joint member (1). The plastic coating is applied by means of a powder-coating technique which results in special properties and which avoids the problems in plastic washers which have hitherto had to be received in a receiving bore or counterbore. Advantages in terms of simplification of production are achieved.

Description

This invention concerns improvements in friction stays. In particular, friction stays for use in windows and of the kind herein defined as comprising one or more arms or links and/or mounting plates (such arms, links or plates herein also called stay parts) that are connected together by one or more friction pivot joints which permit restrained pivotal movement of the stay parts, the stay being adapted and arranged for mounting on a sash and securing to the associated frame so that the sash is supported for frictionally restrained movement on and relative to the frame.

Such stays of the defined kind are conventionally used in pairs, one each side of the sash and associated frame. The sash may be hung on the stays for top, bottom or side opening. The frictional restraint to maintain the sash in an adjusted position is provided in the pivot joints by suitable design and manufacture of the pivot joints.

It is already known to provide in a stay of the defined kind a pivot joint including a rivet which extends through the stay parts with the rivet being clinched in a manner to generate forces which, after clinching, provide the frictional restraint.

Generally, the rivet shank is in tension so that pressure is applied directly or indirectly to the stay parts by the head and clinched tail of the rivet. Accordingly, the rivet is subject to extreme forces in service when the stay supports a glazed sash.

The operation of the stay when fitted in a window must be smooth and wear of the pivot joint must be S1747 avoided. Usually, one of the stay parts is fixed relative to the rivet and this is conveniently the stay part adjacent the clinched tail. Thus the other stay part which is adjacent the rivet head pivots about the rivet shank. To maintain the loads required in the joint for the frictional restraint, metal to metal contact should be avoided to prevent wear.

Furthermore, metal to metal contact is undesirable because of the possibility of corrosion or seizure.

To facilitate such smooth operation and to prevent wear it would appear obvious to fit a washer under the head of the rivet. However, metal washers are generally unsuitable because they may promote wear and corrosion, particularly as a conventional material used for the stay parts is aluminium. The alternative of washers of plastics material would also be assumed to be suitable, but it has been found that they are not because of the characteristic of suitable plastics to creep and deform under the high loads that are generated and maintained in the pivot joint. Such high loads arise from the forces generated during the clinching of the rivet and to obtain the desired performance of the stay the loading in the pivot joint must be sustained in service otherwise the stay will not perform to specification.

To overcome this problem arising with plastics materials, it has been proposed previously to provide a counterbore or similar recess in the stay part underlying the rivet head. The plastics washer or annular bushing is seated in such recess and confined therein by the rivet head to avoid deformation and spreading of the washer.

The recess is essential and is acceptable where the material of the stay part is of sufficient thickness and strength. However, it imposes limitations on size, material and adds to manufacturing costs.

According to this invention, we provide a friction stay of the kind defined wherein the friction pivot joint comprises a rivet clinched to hold two stay parts together for frictionally restrained movement and a washer is interposed between the head of the rivet and a substantially flat and unconfining upper surface of the underlying stay part with the washer comprising a metal substrate coated with a low friction plastics material.

By this invention a washer having the plastics coating is held between the head of the rivet and the underlying stay part and no recess or counterbore is required. This enables the stay parts to be made in thinner section materials and avoids the manufacturing step of counterboring and locating the washer or bushing in the counterbore.

Preferably, the plastics coating is applied and bonded to the metal substrate by a powder coating technique. The plastics material may be selected from suitable low friction materials such as nylon, neoprene, polyester or epoxy resin.

It has been found that such coatings of plastics have properties that are surprisingly different to extruded or moulded forms. In particular, it has been found that when the plastics are applied and bonded to a metal substrate, the plastics coating has mechanical and physical properties such that the plastics is less compressible and less able to deform under load. In the case of certain grades of nylon suitable for powder coating, the increase in resistance to compression is 20 times greater than the nylon in moulded or extruded form. From this surprising finding, it has been possible to provide a coating on a metal substrate which, when subject to the specified loads to be applied, does not spread or deform and can function properly in service by providing the low friction surfaces for the pivotal movement of the stay parts.

Preferably the coating on the metal substrate is between 0.003 to 0.018 (0.08mm to 0.48mm} thick.

It has been found that such range of thicknesses is sufficient to Withstand the clinching pressures and to take up any surface imperfections such as might exist under the head of the rivet and on the underlying surface of the stay part.

Conveniently, the metal substrate is in the form of a flat annular washer and the coating is substantially uniform. It is envisaged that the diameter of the coated washer could be substantially the same or greater than the rivet head.

It will be appreciated that this apparent simple solution overcomes many of the practical manufacturing and design problems associated with mass manufacture of friction stays.

The two relatively movable stay parts associated with each pivot joint may be separated by a spacer, and this may also comprise a washer having a plastics coating bonded thereto. The rivet may be of any suitable kind and can be clinched in any suitable and known manner provided that the residual forces required in the joint are obtained.

This invention is exemplified in the accompanying drawings wherein:51747 FIGURE 1 shows an exploded view of part of a stay with a pivot joint; FIGURE 2 is an enlarged detail section of the washer having the plastics coating; and FIGURE 3 is a front elevation of a stay including the pivot joint shown In Figure 1, the stay being shown in the open position.

With reference to the drawings, the stay comprises an arm or link 1 which is pivotally connected at one end 2 to a plate 3 for mounting on a frame (not shown) . The plate 3 is provided with holes 4 for fasteners to secure the plate to the frame. The other end 5 of the arm 1 is connected to another plate 6 for mounting on a sash (not shown) by means of holes 7 and suitable fasteners. The connections of the arm or link 1 to the plates 3 and 6 are by similar friction pivot joints 8 as later described.

The stay comprises another arm or link 9, of different length also pivotally connected by friction pivot joints 8 to the respective mounting plates 3 and 6. The other arm or link 9 is cranked, and in known manner in the stay the two arms or links 1 and 9 are arranged for pivotal movement so that the mounting plates and the stay arms or links are foldable to overlie each other and to be contained in a rebate extending between the sash and the frame when the sash is in the closed position. On opening of the sash, the arms or links pivot relative to the mounting plates through the respective pivot joints.

Each pivot joint 8 comprises a rivet 10 of which the shank is arranged to extend through a piercing 11 in the substantially flat end 2 of arm 1.

Additionally, the rivet shank is arranged to extend through another piercing 12 in the plate 3. The piercing 12 is plunged from the underside of the plate 3 to provide a recess in which a serrated washer 13 may be received so as not to stand proud of the flat under-surface of the plate 3.

According to this invention, a plastics coated washer 14 is received on the shank of the rivet to be held under the rivet head and on the end 2 of the arm 1. Another plastics coated washer 15 is arranged to separate the end 2 of the arm 1 and the plate 3, and when mounted on the shank of the rivet, the washer 15 is seated on the raised platform 16 provided by the plunge around the piercing 12.

The washer 14 has a plastics coating 16 about 0.008 (0.21mm) thick and comprises a nylon applied to a metal substrate in the form of an annular disc 17 of mild steel. The nylon is applied to such substrate by a powder coating technique.

The serrated washer 13 is arranged to be held adjacent the tail of the rivet on clinching during which operation the tail is rolled in known manner but during which loads are applied to provide the residual tension forces in the rivet shank. The serrated washer 13 is engaged by the clinched tail and ensures that the rivet cannot rotate relative to the mounting plate 3.

In the stay, movement of the arm 1 relative to the plate 3 is about the pivot axis provided by the shank of the rivet and frictional resistance to such movement is provided by the forces transmitted through the abutting faces of the washers, rivet head and stay parts. The plastics coating 16 provides low friction surfaces to ensure smooth action, and also provides resistance to wear, inter-metallic reaction and is corrosion resistant.

The plastics coating may be of any suitable plastics material provided that it is applied by the said powder coating technique which gives the surprising special characteristics. The thickness of the coating can be selected in accordance with the properties required, such as strength, and the interface bonding.

The friction stay may comprise arms, links or plates of different configurations (including sections) depending on the duty required. The recess in the underside of the mounting plate 3 is not essential and if the underside of the plate is required to lie flat on the frame or sash other arrangements to contain the rivet tail can be provided. For instance a longitudinal channel can be provided in the underside of the plate.

As will be understood, different types of rivets of solid or hollow form may be employed. Furthermore, the tail of the rivet may be located relative to the adjacent stay part by seating the serrated or other type of lock washer prior to clinching, or by providing means in the stay part or recess therein to prevent a washer turning therein. Alternatively, serrations or like interference lugs or ribs could be provided in the stay part onto which the tail of the rivet is clinched.

The mounting plates for the stay may be provided with holes or fastening means for use in securing the plates to the respective sash and frame, but these form no part of the present invention.

Published U.K. Patent Application No. 2 083 129A describes and claims a friction stay having plastics coated stay parts (arms or links and/or mounting plates).

Patent Specification No. 5.16 28 describes and claims a friction stay having a friction pivot joint incorporating a plastics coated rivet.

Claims (10)

Claims:

1. A friction stay of the kind defined wherein the friction pivot joint comprises a rivet clinched to hold two stays parts together for frictionally restrained 5 movement and a washer is interposed between the head of the rivet and a substantially flat and unconfining upper surface of the underlying stay part with the washer comprising a metal substrate coated with a low friction plastics material. 10

2. A friction stay according to claim 1 wherein the plastics coating on the washer is applied by a powder coating technique and is selected from the group of plastics materials being nylon, neoprene, polyester or epoxy resin. 15

3. A friction stay according to claim 1 or claim 2 wherein a further plastics coated washer is interposed between the stay parts.

4. A friction stay according to any one of the preceding claims wherein the tail of the rivet is 20 clinched to the underside of a stay part comprising a mounting plate for securing to a window frame.

5. A friction stay according to claim 4 wherein a serrated washer is located voider the tail of the rivet on clinching to prevent relative rotation of the rivet 25 and the mounting plate.

6. A friction stay according to claim 5 wherein the serrated washer is received in a recess formed in the underside of the mounting plate.

7. A friction stay according to claim 6 wherein a 30 platform is formed on the mounring plate on the face opposed to said recess and the further washer is seated on said platform.

8. A friction stay according to any one of the preceding claims wherein one stay part comprises a link or arm of cranked form with a substantially flat end engaged by the plastics coated washer underlying the 5 head of the rivet.

9. A friction stay according to any one of the preceding claims wherein the thickness of the plastics coating on the washer is from 0.003 to 0.018 {0.08mm to 0.46mm).

10. Io. A friction stay of the kind defined and substantially as hereinbefore described with reference to the accompanying drawings.