WO2000005509A1

WO2000005509A1 - Leak resistant fastener

Info

Publication number: WO2000005509A1
Application number: PCT/IB1999/001295
Authority: WO
Inventors: Daniel Manseau
Original assignee: Daniel Manseau
Priority date: 1998-07-20
Filing date: 1999-07-19
Publication date: 2000-02-03
Also published as: AU4640999A

Abstract

A washer assembly for use with a screw (50) having a shaft (64, 66) and a screw head (52), the screw head (52) having a recess (58) formed on an underside thereof, the washer assembly having first and second washer members (12, 42), the first washer member (12) being formed of a resilient material while the second washer member (42) is formed of a material less resilient, the first washer member (12) having a centrally located aperture to receive the screw shaft, the first washer member having an upper section (14), a lower section (16), and an intermediate section (18) between the upper and lower sections, the second washer member being mounted on the first washer member at the intermediate section, the upper section (14) having a diameter which is sized to fit partially within the recess of the screw head, the intermediate section (18) having an intermediate section diameter less than the upper section diameter, and the lower section (16) having a lower section diameter larger than the upper section diameter. The arrangement is such that the upper section under the screw head is compressed during attachment of the screw to a substrate and a sealing action is provided with a peripheral edge of the screw head seating on the second washer member.

Description

LEAK RESISTANT FASTENER

The present invention relates to the field of fasteners and more particularly,

relates to the field of a leak resistant fastener.

BACKGROUND OF THE INVENTION

Fastening screws are widely used in any number of applications. Typically,

they are used for attaching an element to a substrate, the screws being designed to

securely hold the same.

Although screws are widely used, they normally are not used wherein a

relatively leak resistant arrangement is required between the assembled components.

Thus, the shank of a screw having threads thereon forms a helicoidal thread which

extends through the components and this usually renders the assembly somewhat

susceptible to leaking.

There are certain situations wherein such leaking is not acceptable and such

situations would include the attachment of building or roof panels to an underlying

substrate. Building panels for use as roof and fascia portions of building structures are

well known in the art. Many such building panel structures are arranged to have an

interlocking relationship at their edges to orient the building panel structures relative

to another and also to protect against the entry of moisture. However, the attachment

of these panels has suffered from the possibility of moisture penetration through

conventional fastening screws. Many building panel structures are designed for

aesthetic appearance and an interlocking relationship, but do not provide for the

development of structurally self sufficient wall and roof portions which will support

uniformly distributed loads without any additional structure. There have been attempts in the past to devise fasteners which are leak

resistant. Thus, various types of screws having washers associated therewith have

been employed. These washers have been usually manufactured of a fibrous or

polymeric material.

It is known that wind and other forces produce vibration tending to cause such

a screw to work loose by causing the washer to act as a lever transmitting forces to the

screw head. In order to overcome this, it has been proposed in the art to form an

integral assembly of a screw and a roofing washer which tends to make it more

difficult for the screw to work loose. However, such integral assemblies are relatively

expensive to manufacture and often special tools are required for their installation.

They still remain susceptible to the problem of leakage. Thus, when the conventional

sealing washer is pressed by the screw head in order to prevent water from seeping

through the apertures, the peripheral region of the sealing washer normally extends

outwardly past the peripheral edge of the screw and thus is not covered or protected

by the head. The peripheral region is thus exposed to the elements including the air

and solar rays which tend to drastically reduce its effective service life.

In addition, such screw fasteners generally do not have an aesthetically

appealing outward appearance. This is particularly so when deformation and cracking

of the washer occurs after prolonged exposure to environmental elements such as the

sun and air borne pollution. Thus, after the fastener has been driven into the structural

member, the washer will often crack and deform and pieces will break off allowing

moisture to easily leak into the assembled structure. It has also been proposed to provide a screw wherein an elastomeric washer is

mounted under a conventional metal washer with both washers being adapted to be

sandwiched between the screw head and the panel being attached. However, since

roofing panels tend to flex under forces exerted thereon such as wind or the weight of

snow, the elastomeric washer tends to remain compressed in its original configuration

and subsequently water can infiltrate between the screw head and the metallic washer.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an improved

fastening device which is easy to manufacture and provides easy assembly of the

components while maintaining a leak resistant connection.

According to one aspect of the present invention, there is provided a washer

assembly for use with a screw having a shaft and a screw head, the screw head having

a recess formed on an underside thereof, the washer assembly comprising first and

second washer members, the first washer member being formed of a resilient material,

the second washer member being formed of a material less resilient than the material

forming the first washer member; the first washer member having a centrally located

aperture sized to receive the screw shaft, the first washer member having an upper

section, a lower section, and an intermediate section between the lower and upper

sections; the washer assembly being characterized by the upper section having an

upper section diameter sized to at least partially fit within the recess of the screw

head; the intermediate section having an intermediate section diameter less than the

upper section diameter; the lower section having a lower section diameter larger than the upper section diameter; the second washer member having a second washer

member aperture extending therethrough, the second washer member aperture having

an aperture diameter at least substantially equal to the intermediate section diameter

and less than the upper section diameter.

According to a further aspect of the present invention, there is provided a

washer and screw assembly comprising a screw having a shaft and a screw head, the

screw head having a recess formed on an underside thereof, the washer assembly

comprising first and second washer members, the first washer member being formed

of a resilient material, the second washer member being formed of a material less

resilient than the material forming the first washer member, the first washer member

having an upper section, a lower section, and an intermediate section between the

upper and lower sections, the washer and screw assembly being characterized by the

first washer member being placed on the shaft of the screw whereby the upper section

fits partially within the recess of the screw head, the intermediate section having an

intermediate section diameter less than the upper section diameter, the lower section

having a lower section diameter larger than the upper section diameter, the second

washer member fitting between the upper section and the lower section.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus generally described the invention, reference will be made to the

accompanying drawings illustrating an embodiment thereof, in which:

Figure 1 is an exploded perspective view of a screw and washer assembly

attaching a first member to a substrate; Figure 2 is a top plan view thereof;

Figure 3 is a side elevational view thereof;

Figure 4 is a side elevational view, partially in section, of a first washer

member of the washer assembly;

Figure 5 is a top plan view of the first washer member of Figure 6,

Figure 6 is a partial side cross sectional view of the screw and washer assembly

used in Figure 1 in a non-compressed position; and

Figure 7 is a partial sectional view of the screw and washer assembly of

Figure 1 in a compressed condition.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings in greater detail and by reference characters thereto,

there is illustrated in the Figures a screw and washer assembly generally designated

by reference numeral 10 and which screw and washer assembly 10 is used to secure a

panel having a corrugation 82 to a substrate 84 ( Figure 3 ). The arrangement shown

is that typically used in construction for securing such panels.

The screw and washer assembly includes a first washer member generally

designated by reference numeral 12 as best seen in Figures 4, 6 and 7 and to which

reference will now be made. First washer member 12 is characterized by having an

upper section 14, a lower section 16, and an intermediate section 18 between upper

section 14 and lower section 16.

Upper section 14 includes an annular side wall 22 and a top wall 24. Between

annular side wall 22 and top wall 24, there is provided a chamfered surface 26. A bottom wall of upper section 14 extends inwardly to meet an intermediate section

side wall 30.

Lower section 16 has an annular side wall 34, a relatively flat bottom wall 36,

and a sloping top wall 38 extending between intermediate section side wall 30 and

side wall 34 of lower section 16.

The screw and washer assembly also includes a second washer member which

is best seen in Figures 1, 6 and 7 and which is generally designated by reference

numeral 42. Second washer member 42 has an annular side wall 44, a top wall 46

which is of a sloping convex configuration, and a concave bottom wall 48. An

aperture is centrally located in second washer member 42.

First washer member 12 is formed of a resilient material, and is preferably

formed of an elastomeric material such that the same can be compressed and it also

has a memory such that when it is compressed, it will be resiliently biased against the

compressing force. Second washer member 42 is of a less resilient material than first

washer member 12 and in a preferred embodiment, is of any suitable metallic material

which is preferably resistant to corrosion.

Screw 50 has a screw head 52 which has a concave upper surface 54 and a

convex lower surface 56. The arrangement is such that there is provided a lower

recess 58 defined by convex surface 56 and which extends to the peripheral edge 59 of

screw head 52. A recess 60 is provided in upper surface 54 for receiving the head of a

screw driver or other tool.

Screw 50 has an upper shaft portion 64 adjacent screw head 52 and a lower shaft portion 66 having threads 68 formed thereon. Upper shaft portion 64 preferably

is not provided with screw threads.

In use, second washer member 42 is placed over upper section 14 of first

washer member 12 such that it will seat within the recess defined by intermediate

section 18. As will be noted, upper section 14 has a diameter greater than the

diameter of the aperture in second washer member 42. Thus, second washer member

42 is retained in position between upper section 14 and lower section 16. Preferably,

the aperture in second washer member 42 is sized such that the same will seat snugly

against intermediate section side wall 30.

Annular side wall 22 of upper section 14 is preferably of a height which is at

least slightly greater than the distance between convex lower surface 56 and a plane

defined by the peripheral edge 59 of screw head 52. Thus, when upper section 14 is

placed within lower recess 58 of screw head 52, there is a slight compressive force

acting thereon.

It will also be noted that second washer member 42 has a diameter which is

slightly greater than the diameter of lower section 16 of first washer member 14 and is

also greater than the diameter of screw head 52.

Figure 7 illustrates the screw and washer assembly in a tightened position and

wherein peripheral edge 59 of screw head 52 will contact concave upper surface 54 of

second washer member 42. However, the compressed upper section 14 prevents the

over tightening of the screw and prevents the lower section 16 from being unduly

deformed while enabling a proper sealing.

Claims

I CLAIM:

1. A washer assembly for use with a screw (50) having a shaft (64, 66) and a

screw head (52), the screw head (52) having a recess (58) formed on an underside

thereof, said washer assembly comprising first and second washer members (12, 42),

said first washer member (12) being formed of a resilient material, said second washer

member (42) being formed of a material less resilient than said material forming said

first washer member; said first washer member having a centrally located aperture

sized to receive said screw shaft, said first washer member having an upper

section (14), a lower section (16), and an intermediate section (18) between said lower

and upper sections; the washer assembly being characterized by:

said upper section (14) having an upper section diameter sized to at least

partially fit within said recess (58) of said screw head (52);

said intermediate section (18) having an intermediate section diameter less than

said upper section diameter;

said lower section (16) having a lower section diameter larger than said upper

section diameter;

said second washer member (42) having a second washer member aperture

extending therethrough, said second washer member aperture having an aperture

diameter at least substantially equal to said intermediate section diameter and less than

said upper section diameter.

2. The washer assembly of Claim 1 wherein said first washer member (12) is

formed of an elastomeric material.

3. The washer assembly of Claim 2 wherein said second washer member (42) is

formed of a metallic material.

4. The washer assembly of Claim 1 wherein said upper section (14) has a height

greater than a height of said recess (58) in said screw head (42) when said first section

is in an uncompressed state.

5. The washer assembly of Claim 1 wherein said lower section diameter is less

than a diameter of said second washer member (42).

6. The washer assembly of Claim 1 wherein said second washer member (42) has

an upper surface (54) sloping downwardly from said second washer member aperture

towards a peripheral edge (44) of said second washer.

7. The washer assembly of Claim 6 wherein said lower section (16) of said first

washer member (12) has an upper surface (38) thereof sloping downwardly to mate

with said downwardly sloping surface of said second washer.

8. The washer assembly of Claim 1 wherein said first washer member and said

second washer member have a substantially circular outline.

9. A washer and screw assembly comprising a screw having a shaft and a screw

head, said screw head having a recess formed on an underside thereof, said washer

assembly comprising first and second washer members, said first washer member

being formed of a resilient material, said second washer member being formed of a

material less resilient than said material forming said first washer member, said first

washer member having an upper section, a lower section, and an intermediate section

between said upper and lower sections, the washer and screw assembly being characterized by said first washer member being placed on said shaft of said screw

whereby said upper section fits partially within said recess of said screw head, said

intermediate section having an intermediate section diameter less than said upper

section diameter, said lower section having a lower section diameter larger than said

upper section diameter, said second washer member fitting between said upper section

and said lower section.