GB2185081A - Screw anchor - Google Patents

Abstract

A one-piece screw anchor 1, for insertion into a hole in a thin wall and to receive a screw 12 serving to cause the anchor 1 to widen out and abut the rear face of the wall, has a pair of spaced legs extending between a stop 2, 10 at one end and a nut 6 at the other end, the stop 2,10 being formed by a separate member on each leg apertured at 11 to receive the screw 12 with clearance, each leg including a shank 3,9 integral with the apertured stop 2,10, a locking arm 4,8 integral with the shank 3,9, and a thrust member 5,7 integral with the locking arm 4,8 and with the nut 6,the locking arms 4,8 being splayed outwards towards the thrust members 5,7 such that tightening of the screw 12 causes the nut 6 to be drawn towards the stop 2,10, the thrust members 5,7 urging the locking arms 4,8 to a more splayed condition, for example flat against the rear face of the wall. The anchor 1 grips the wall of the hole by its own resilience to prevent rotation. <IMAGE>

Description

SPECIFICATION Screw anchor This invention relates two a screw anchor which can be inserted through a hole in a wall, or a assembly of walls, and which can receive and coactwith a screw passed through it from thefrontofthewall(s) to the rear thereof such that by subsequent rotation of the screwtotighten zit a portion of the anchor externally of the rearface of the wall(s) can be caused to deform and widen out to abutthe rearface ofthewall(s) adjacent the hole.

Afirst object of the invention is to provide an improved structure for such a screw anchorwhich permits it to be made as a one-piece body having a stop means for abutment against one face of the wall(s) and a threaded nutmemberforengagementbythe screw, both of which are supported laterally in a manner providing greater inherent strength than hitherto.

A second object of the invention is to provide in such a screw anchor a feature of resilience enabling the anchorto be introduced into the hole in a somewhat splayed state such that it is resiliently deformed as it is pushed fully home in the hole, and the resulting frictional engagement of the anchor with the wall surface ofthe holetendsto preventtheanchor rotating during insertion and tightening ofthe screw.

According to the present invention a screw anchor comprises a one-piece body having a pairofspaced legs extending between a stop means at one end of the body and a threaded nut member at the other end ofthe body, the stop means including a pairof apertured members which can be aligned to receive a screw with clearance, each such leg including a shank integral with the respective apertured member, a locking arm integral with and extending from the shank, and a thrust member integral with and extending from the locking arm and integral with the threaded nut member, the locking arms being splayed towards the thrust members such that, upon tightening of the screw to drawthethreaded nut membertowards the stop means, the locking arms are deformed to a more splayed condition.

Asthestop means is constituted bya pairof apertured members each of which is carried on a respective leg, the stop means as a whole is supported symmetrically at both sides by the body. Similarly, the threaded nut member is supported symmetric- ally at both sides of the body.

Preferably the screw anchor is manufactured in a state in which the two legs are initially somewhat splayed sothatthe apertured stop members are not overlapped, or not overlapped sufficiently for align- ment oftheir apertures, the body as a whole being made of a resiliently deformable material which is such as to permit springy deformation of the body as it is inserted in a hole in a wall so asto result infriction grip between the body and the wall to prevent inadvertent rotation ofthe anchor during tightening of the screw.

Advantageously, the points of connection ofthe shankand/orthethrust member with the locking arm are made relativelyweakfor preferential bending at the preach point of connection. Byway of example, the locking arm may be made of generally lesser width than the shank and the thrust member, and in particularthe shankand1orthethrust member may be provided with a reinforcing formation such as lon gitudinal ribbing.

In use, a hole ofjustgreaterdiameterthanthe overall transverse dimensions of the anchor (when the clearance apertures to receive the screw are adequately aligned) is made in the wall, or assembly of walls to be joined bythe anchor. The anchor is pushed into the hole, with resilient deformation of its legs, and abuts frictionally against the interior of the - hole. The screw is inserted through the aligned clear ance holes and is engaged by its free end with the threaded nut member.Tightening of the screw causesthenutmemberto be drawntowardsthe pair of stop members until the latter are tightly abutted against the front face ofthewall and the locking arms have been splayed further out to abut against the rearface of the wall, in which position they are firmly supported by the rust members. If the length of the shanks is exactlyequal tothe length ofthe hole inthe wall,the locking arms will be pressedfirmlyflat against the rearwall.Desirably, the length ofthe shanks is selected, relative to the thickness ofthe wall(s) so that said length and thickness are equal, or so that the length of the shanks is somewhat greater than the thickness ofthewall.

In order that the nature of the invention may be readily ascertained, an embodiment of screw anchor in accordance therewith is hereinafter particularly described with reference to the figures ofthe ac companying drawing,wherein: Figure lisa perspective elevation of the screw an chor, ready to receive a screw: Figure 2 is a perspective elevation of the screw an chorwith a screw inserted; Figure 3 is a perspective elevation of the assembly of screw anchor and screw engaged in -a-hole in a wall and tightened to cause collapse of the anchor againstthe rearofthewall; Figure 4 is a perspective elevation of the screw an chorto illustrate a feature of resilience.

Referring to the drawing, the screw anchor is des ignated generally by reference numeral 1 and has a one-piece body which includes, taken from endto end, a first stop plate 2, a first shank 3, a first locking arm 4, a first thrust member 5, a threaded nut member 6, a second thrust member 7, a second locking arm 8, a second shank 9, and a second stop plate 10.

Each ofthe stop plates 2 and 10 has an opening 11 which is a clearance fitfor a screw 12 which can be passed through the substantially aligned openings 11 and then threaded at its free end into the thread- ing ofthe nut member 6.

Referring to Figures2 and 3, in useforengagement into a wall 13, shown in broken line, a hole 14 of just slightly overall diametergreaterthantheoverall dimensions ofthe anchor is drilled through the wall 13.Then the anchor 1, in its state as seen in Figure 1, is pushed home in the hole 14 untilthe innerface of.

the second stop plate 10 is abutting the frontface of the wall.

The screw is inserted and threaded into the nut member 6. Sufficient rotation of the screw 1 will then cause the nut member 6to be drawn towards the stop plates 2 and 10. The shanks 3 and 9 are reinforced against longitudinal bending by the presence in them of respective ribs 3a and 9a. The thrust members 5 and 7 are likewise reinforced against longitudinal bending by the presence in them of respective ribs 5a and 7a. The locking arms 4 and 8 are connected to the adjacent shank and thrust member by relatively narrow zones 15 and 16.Accordingly, as the nut member 6 is forced towards the stop plates, bending occurs atthezones 15 and 16, with further splaying out ofthe thrust members Sand 7, until the locking arms4and 8 have become pressed flat againstthe rearface ofthewall 13.

The screw anchor is then firmly held in the hole 14 by its stop plate(s) 2 and 10, of which the latter dir ectly abuts thefrontface of the wall, and by its locking arms 4 and 8 which directly abut the rearface ofthewall.

It will be appreciated thatthe wall 13 could likewise be two or more sheets or panels to be secured together.

The screw anchor is preferably made as a whole of a resiliently deformable material, e.g. sheet steel, and formed by stamping and punching so asto have, initially, the slightly splayed shape seen in Figure 4.

In this state, the two arms of the anchor are splayed sothatthetwo stop plates 2 and 10 are not initially overlapped.Theanchorcanthusbeforced intothe hole 14 and, by its own resilience, will urge the port ions 3-4-5 and 7-8-9 outwardly to g rip firm ly against the wall ofthe hole 14, thereby tending to prevent the anchor rotating as a whole during insertion ofthe screwand itstightening to deform the anchor.

Claims (8)

1. A screw anchor comprising a one-piece body having a pair of spaced legs extending between a stop means at one end ofthe body and a threaded nut member atthe other end of the body, said stop meansincluding a pairofapertured members the apertures ofwhich are alignable and can receive a screwwith clearance, each such leg including a shank integral with the respective apertured member, a locking arm integral with and extending from the shank, and a thrust member integral with and extending from the locking arm and integral with the threaded nut member, said locking arms being splayed in the direction towards the thrust members such that, upon tightening of a screw positioned through said apertures and engaged threadedlywith said nut, said nut member is drawn towards said stop means and said thrust members urge said locking arms to a more splayed condition.

2. Ascrewanchor, as claimed in claim 1,wherein portions of the leg forming a connection of the shank and/or the thrust member with the locking arm are made relatively weakfor preferential bending atthe connection.

3. A screw anchor, as claimed in claim 2, wherein said connection portions of the leg are of lesser width than the shank and the thrust member.

4. A screw anchor, as claimed in any one of claims 1 to 3, wherein theshankand/orthethrust member of each leg are provided with aformation reinforcing them against bending.

5. A screw anchor, as claimed in claim 4, wherein said reinforcing formation is longitudinal ribbing.

6. A screw anchor, as claimed in any one of claims 1 to 5, made as a whole of resiliently deformable material and having, in the unconstrained state, its two legs splayed in the direction from the nut membertowards the stop means, such that said apertures are not in alignment.

7. A screw anchor substantially as described herein with reference to Figures 1 to 3 ofthe accompanying drawings.

8. A screw anchor substantially as described herein with reference to Figure 4 of the accompanying drawings.