EP0397733A1

EP0397733A1 - Wall plugs

Info

Publication number: EP0397733A1
Application number: EP19890901577
Authority: EP
Inventors: Martin Edward Chamberlain
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-01-06
Filing date: 1989-01-05
Publication date: 1990-11-22
Also published as: GB8800214D0; GB2214591A; WO1989006321A1

Abstract

La feuille de plastique décrite (10) comporte des nervures parallèles (12, 14) réparties uniformément sur les deux surfaces. La feuille peut être découpée dans le sens transversal et dans le sens longitudinal des nervures en parties pouvant être pliées dans le sens parallèle des nervures pour former des chevilles murales.The described plastic sheet (10) has parallel ribs (12, 14) distributed uniformly over the two surfaces. The sheet can be cut in the transverse direction and in the longitudinal direction of the ribs into parts which can be folded in the parallel direction of the ribs to form wall plugs.

Description

WALL PLUGS

The present invention relates to plastics wall plugs.

Plastics wall plug are well known for fixings screws in brickwork, plaster and building blocks. These usually consist of a cylindrical or tapering hollow body with projections on its inner and outer surfaces. A hole of the appropriate diameter is drilled in the wall and a plug is inserted into it. A screw can then be driven into the plug and as it is driven home, it grips the inner projections of the plug and expands the plug so that the outer projections grip into the wall.

Commonly, the plugs are individually formed to suit a limited size of screw and hole, both in diameter and in length. In the case of cylindrical plugs, it is also known to form a long tube of plug material from which the appropriate length of plug can be cut. In this case, the plug is not limited as to length but is still restricted as to diameter.

A professional builder will normally keep a variety of plugs in many sizes but this is not practicable for a do-it-yourself handyman. To meet the needs of the non- professional builder, packets of plugs containing different sizes have been proposed but a handyman may often find that the size required is the one that has already been exhausted.

The present invention seeks to mitigate the foregoing disadvantages and to provide a plug material from which plugs to suit a wide variety of lengths and diameters can be cut.

According to the present invention, there is provided a plastics sheet characterised in that parallel ribs arc uniformly distributed over both surfaces of the sheet, ana in that the sheet is capable of being cut across and along the ribs into smaller pieces each of which can be bent parallel to the ribs to form a wall plug.

Preferably, on each surface the ribs are of two different heights, and comprise taller ribs alternating with shorter ribs.

In the preferred embodiment of the invention, the shorter ribs on one surface of the sheet are aligned with the taller ribs on the other surface.

The shorter ribs are conveniently triangular in section but the taller are preferably formed as a trapezium or truncated triangle. The sloping sides of the ribs permit the sheet to be rolled without the ribs colliding with one another.

A variety of plastics materials may be used in manufacture of the sheet but it is preferred that it be formed from polypropylene or high density polythene.

These provide an acceptable comprise between flexibility, ease of cutting and gripping of the screw and the wall.

The sheet is conveniently formed by injection moulding and if desired the sheet may comprise a hole or handle portion to enable it to be suspended.

In use, a plug is formed by cutting a small rectangle from the sheet. The height of the rectangle, measured along ribs, corresponds to the desired length of the plug whereas the width of the rectangle or the number of ribs on the rectangle, is selected to suit the diameter of the hole and the screw. The rectangle cut frcr. the sheet is now folded or rolled parallel to the ribs tc form a plug which can be inserted into a hole ir. a w_.ll to receive a screw. it is known from GB 1,089,586 to form a plug by rolling a flat sheet with ribs on one surface and grooves on another. The edges of the sheet are not ribbed in this case and overlap one another in the hole. This design of this plug prevents it from being cut from a large sheet which is uniformly ribbed to enable plugs to be cut to suit different diameters of hole.

The invention will now be described further, by way of example, with reference to the accompanying drawings, in which:-

Figure 1 is a plan view of a plastics sheet from which wall plugs can be cut, and

Figure 2 is a partial section drawn to an enlarged scale through the sheet of Figure 1 along a line transverse to the ribs on the sheet.

The sheet 10 in the drawings is an injection moulded sheet of polypropylene or high density polythene. Both surface of the sheet are the same when viewed in plan. Along the length of each surface of the sheet, as better shown by the section of Figure 2, there are taller trapezoidal ribs 12 alternating with shorter triangular ribs 14. The taller ribs 12 on one surface are directly in line with the shorter ribs 14 on the other surface. A handle (not show) can be moulded along the upper edge of the sheet or a hole may be formed in the sheet εc that it may be suspended on a nail for ease of location while working.

To make a wall plug for any particular application, a rectangle is cut from the sheet and bent over parallel between the ribs. Because the sheet is ribbed over its entire surface and the ribbing is homogeneous any desired length and width of rectangle car. be cut frcr any part of the sheet. ^•rne length of the rectangle measured along the ribs is determined by the desired length of the plug, which of course depends on the length of the screw and the depth of the hole in the wall. The width of the rectangle should correspond approximately to the perimeter of hole. The web between the various ribs will lie near the surface of the hole on the wall. The the ribs 12 and 14 projecting outwards from the web will grip the wall while the ribs projecting radially inwards from the web are gripped by the screw. The sheet can be rolled up tightly for ease of insertion into the hole in the wall and as with a conventional wall plug, it is expanded upon insertion of the screw to grip the wall tightly.

It is not intended that the edges of the rectangular should be overlapped when the drill bit used for the hole in the wall correctly matches the screw size. Indeed the edges need not even meet for proper anchorage to occur.

Whereas a professional tradesman can usually be relied upon to have the correct drill sizes, it is not uncommon for an amateur to use the wrong drill bit and try to insert a screw into an oversized hole. Kith conventional plug, this present a problem. If a large plug is used, it will properly fit the hole but will not be expanded sufficiently by the screw to grip the wall, whereas if a small plug is used, even the fully expanded plug will not properly be anchored in the wall.

In the present invention, if the plug is found too small for the hole, either a new larger plug may be cut from the sheet and this time inserted with its edges overlapping, or else a thin length cut from the sheet and comprising only one or two ribs may be inserted between the small plug and the wall. The -plug car. in this way be varied in thickness to take ur ar.y σaj. caused by an oversized hole. A particular advantage of the invention is that substantial ribs project outwards into the wall and this makes the plug well suited for use in soft building block which tend to crumble when a wall plug is used having only short projecting ribs. In this case, despite the large projections from its outer surface, the plug can still be introduced into the hole because it can be tightly curled up on itself and as the screw is driven home the flat ends of the taller ribs gradually become embedded in the surface of the hole and prevent the plug from turning as the screw is tightened.

Claims

1. A plastics sheet characterised in that parallel ribs (12, 14) are uniformly distributed over both surfaces of the sheet (10) , and in that the sheet (10) is capable of being cut across and along the ribs (12, 14) into smaller pieces each of which can be bent parallel to the ribs (12, 14) to form a wall plug.

2. A plastics sheet as claimed in claim 1, characterised in that, on each surface, the ribs (12, 14) are of two different heights, and comprise taller ribs (12) alternating with shorter ribs (14) .

3. A plastics sheet as claimed in claim 2, characterised in that the shorter ribs (14) en one surface of the sheet are aligned with the taller ribs (12) on the other surface.

4. A plastics sheet as claimed in claim 2 or 3, characterised in that the shorter ribs (14) are triangular in section and the taller (12) are ribs are trapezoidal in section.

5. A plastics sheet as claimed in any preceding claim, characterised in that the material from which the sheet (10) is formed in polypropylene or high density polythene.

6. A plastics sheet as claimed in any preceding claim, characterised in that the sheet (10} is formed by injection moulding.

7. A plastics sheet as claimed in claim 6, characterised by means formed integrally with the sheet (10) to enable the latter to be suspended.