IL34181A

IL34181A - Expansion member for anchoring bolt-type fastening means

Info

Publication number: IL34181A
Application number: IL34181A
Authority: IL
Original assignee: Fischer Artur
Priority date: 1969-03-29
Filing date: 1970-03-27
Publication date: 1973-05-31
Also published as: HU164602B; IE34064B1; CH505992A; YU68870A; NL7004427A; ES377998A1; AT298017B; YU32341B; DK125341B; BE747930A; CS166254B2; IE34064L; DE1947369B2; IL34181A0; DE1947369A1; SU381238A3; SE357803B; NO129215B; GB1303539A; RO55670A

Description

Expansion element for anchoring wall plugs ARTUR FISCHER C: 32096 This invention relates to an expansion element for anchoring wall plug in a hole in a wall.

Holes drilled in walls in which expanding wall plugs are to be anchored are usually produced by means of a special drilling tool comprising a drill shank and a detachable drill bit. In order to cater for the severe conditions to which the tool is subjected* these drill bits usually have cutting edges of hard metal. Once the edges are blunted and regrinding is no longer possible, the waste drill bit must be replaced by a new drill bit, and this costs time and money.

According to the present invention there is provided an expansion element for anchoring a wall plug in a hole in a wall, the expansion element being provided at one end with cutting edges constituting a drill tip and having a wedge portion for e-xpanding the wall plug.

Preferably the expansion element is detachably connoctable to a drill shank.

In a preferred embodiment one or more projections is or are provided on the wedge portion, the projections extending substantially longitudinally of the expansion element and away from the drill tip, the projections being engageable in matching recesses of the shank to prevent relative rotation between the shank and the expansion element.

Advantageously, the matching recesses of the shank merge with helical flutes provided therein for the discharge of bring dust, the recesses running parallel with the axis of the shank in the region at which the projections of the expansion element are engageable.

These projections have a shape such that their height provided with the cutting edges. This imparts wedge-like properties to the expansion element, facilitating the subsequent spreading apar of the wall plug. However, these projections may also take the shape of ledges or tenons and may be arranged at the most convenient points of the expansion element, depending upon the design of the expanding end portion of the wall pTag to be used.

In another embodiment the expansion element comprises an elongated flat member* the end of the element remote from the drill tip being insertable into a slot formed in the end of a drill shank to connect the shank and the element together and prevent relative rotation therebetween.

Preferably a longitudinally extending projection is provided on two opposite lateral surfaces of the expansion element, the projections being displaced in diametrically opposite directions from the longitudinal axis of the expansion element, the projections being engageable with recesses formed a diametrically opposed side edges of the slot of the drill shank.

Advantageously,1,÷ the wall plug also act ons as the drill shank.

To facilitate the spreading action of the wall plug, the projections may, according to another feature of the invention, be of convex shape.

The projections, starting from that end of the expansion element opposite that provided with the cutting edges, may gradually emerge from the surface of the flat piece until they reach their greatest height. However, it would also be possible for the projections to taper off gradually from their thickest point towards both ends.1 This design makes it possible to drive plug is used as the drill shank* Here, the expansion element is stopped by a suitable ledge of the longitudinal slot of the wall plug which will thus not be spread apart during drilling.

After the drilling operation the expansion element is turned round and driven into the longitudinal slot of the cutting edges first. If the expansion element consists of a flat member and the projections are arranged centrally, all four expanding legs of a double-slot wall plug can be spread apart in all four directions. This provides for excellent, uniform expansion and excellent drilling action such as is typical for a flat bit.

Further according to the present invention a method of anchoring a wall plug in a hole, in a wall comprises the step of attaching an expansion element, having a wedge portion and at one end cutting edges constituting a drill tip, to a drill shank, drilling a hole in a wall, detaching the shank from the expansion element which latter remains in the drilled hole and Introducing the wall plug into the hole so that it is expanded by the expansion element to grip the walls of the hole. Preferably the wall plug also constitutes the drill shank, the wall plug being provided with recesses for engagement with the expansion element during drilling, the wall plug being detachable from the expansion element so that when the hole is drilled, the wall plug can be rotated relative . to the expansion element and can then be pushed into engagement therewith to be expanded into gripping contact with the walls of the hole.

In order to provide easily expanding legs, the longitudinal slot of the wall plug penetrates it to a depth much greater than the length of the recesses provided for engaging the projections of the expansion element. The shorter recesses prevent deformation of the Further according to the invention, the wall plug for use with an expansion element may comprise a polygonal hollow r@d twisted about its longitudinal axis, with retaining means at one end and a longitudinal slot at the other end, the slot being widened towards this end in a stepwise manner.

In order that the wall plug should be usable as a drill shank, it must be provided with means for discharging the boring dust. If a polygonal rod is twisted about its longitudinal axis, grooves for discharging the boring dust are obtained in simple manner which wind helically about the longitudinal axis of the wall plug. By the stepwise tapering of the longitudinal slot a ledge is formed which serves as a stop in the longitudinal direction of the wall plug for the attachment of the expansion element. Since the longitudinal slot provided in the wall plug is usually longer by a certain amount than the overall length of the expansion element, the step in the slot ensures that, during drilling , the actual bit always projects beyond the end face of the wall plug. ihe invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a perspective representation of an expansion element comprising a wedge and a drilling bitj Figure 2 is a perspective representation of another form of expansion element having a wedge and a drilling bitj Figure 3 shows the shank of a drill which receives the expansion element o .Figure 1 or Figure 2} Figure 4 shows a threaded wall plug that can be expanded by means of the expansion element of Figure .1 or Figure 2 ; Figure 5 shows another form of wall plug having recesses for engaging an expansion element such as shown in Figure 1 or in Figure 2 } -ί Figure β Is a perspective representation of the further form of expansion element; Figure 7 is an end view of the expansion element of Figure 6} Figure 8 is a cross-sectional view showing another form of expansion element fitted to the shank of a drill; and Figure 9 shows a drill shank in perspective view* Referring to the drawings, Figure 1 shows an expansion element 1 consisting of an elongated flat member having at one end a wedge portion 2 and at its other end a drilling bit 3, which latte is provided with cutting edges 4·; The wedge portion 2 is provided with a U-shaped incision 5, the projections 6 formed by the legs of the U being conically tapered towards their free ends. In the centre of each of the opposite surfaces 8 of the expansion element 1 is provided an additional tapered projection 9. The bottom of the U-shaped incision 5 forms a stop surface 7.

The expansion element 10 shown in Figure 2, unlike the expansion element 1 illustrated in Figure 1, has a drilling bit 11 which is thinner than its wedge portion 2 ,, In all other respects, apart from the absence of projections 9, the element 10 is similar to the element 1·; Figure 3 shows a shank 12 of a drill, the shank 12 having flutes 13 for the discharge of boring dust. At one end face 14 of the shank 12 is provided with a central recess 15, the dimensions of which are such that the expansion element 1 can be fixed to the shank 12 with its bit 3 and projections 9 clear of the end 14 and with its stop surface 7 bearing on the bottom of the recess 15.

Similarly the expansion element 10 can be fixed to the shank 12 xiith its bit 11 projecting beyond the end surface 14. The flutes that the lateral surfaces 17 of the axially extending flutes 13 and the lateral walls 18 of the recess 15 co-operate with the projections 6 to prevent rotation of the expansion element 1 or 10. The part of the shank 1 denoted by the numeral 19, opposite the end 14, B clamped in the chuck of a rotary percussion drill, not shown here.

The expansion element 1 or 10 is fitted to the shank 12, and a hole is drilled in a wall by means of the drill bit 3 or 11. Shank 12 is withdrawn from the hole and, thereafter, the wedge portion 2. of the expansion element 1 or 10 serves for spreading apart, and thus anchoring, a wall plug 20 which is hammered into the hole.

The expansion element 1 or 10 can be fitted to the shank 12 easily and simply, and the projections 6 will bear on the lateral surfaces 17 of the flutes 13, so that an efficient anti-rotational safeguard is provided without the risk of the projections 6 bending. During drilling* the boring dust ie guided from the cutting edges 4 directly into the flutes 13, and this ensures the, . uniform discharge" o the boring dust awa from the cutting edges 4 during a continued drilling operation and prevents the jamming of the drill sshank 12 in the hole.

Figure 4 illustrates a wall plug 20 which, at one end face 21 is provided with a conlcally tapered notch 22 terminating in a longitudinal slot 23 which extends down to almost half * the length of the wall plug 20. The expanding legs 24 thus obtaining are spread apart when the wall plu 20 is driven onto the expansion element 1 or 10. Sawtooth-like re-entrant annular grooves 25 are provided on the expanding legs 24.; Originating from the other end face 26 of the wall plug 20, a retaining screw thread means of a nut.

The wall plug 28 Illustrated In Figure 5, which also serves with as the drill shank, has, in addition to the slot 23/which the wall plug 20 of Figure 4 is provided, an axially extending slot 29 which can receive the ex nsion element 1 or 10. The slot 29 is displaced relative to the plane of the longitudinal slot 23. The projections 6 of the expansion. element 1 or 10 engage longitudinally milled recesses 30 extending in axial direction adjacent the slot 29.

Figure 6 shows another form of expansion element 101 having projections 109 integrally formed on its longitudinal faces to form a wedge portion, these projections extending in substantially the longitudinal direction of the shank to which the element 101 is to be fixed. The projections each have a bearing surface 140 i-fhlch extends .In the same longitudinal direction. According to the embodiment of Figure 7, these projections 109 may be integrally moulded by cold flow pressing qr, according to Figure 8, by a stamping process. The drill shank 119 (Figure 9) is provided with a longitudinal slot 123 into which the expansion element can be fitted while the hole is drilled. The shank 119 also has mutually displaced recesses 141 on different sides, matching the alternative arrangement of projections 109 on the expansion element 101.

When the expansion element is inserted in the longitudinal slot 123 of the shank 119 the longitudinal edges 140 of the projections 109 apply themselves to the surfaces 142. In this way the expansion element 101 is centred and guided at the same time. Starting from the end 143 of the expansion element 101, the projections 109 gradually thicken towards their highest point. They are outwardly convex, so that they bear on the lateral surfaces It will be seen that the above-described embodiments result in a time saving, simple way of producing a hole and for fastening an object to a wall plug Inserted therein, especially if a rotary percussion drill is used.. For every drilling and fastening operation a serviceable drill bit with sharp cutting edges is immediate ly available which, later, serves as an expansion element. The regrinding or replacement of blunted or broken cutting edges is no longer necessary. The material and the hardness of the parts of which the drill is . composed may be determined according to the reduced edge life of the tool, since the edges need only remain sharp during the time a single hole is drilled. This is a further cost-saving factor. Besides, the fittin of the expanding wedge to the shank portion is a much simpler operation than the detachment and refitting of conventional drills in the chuck of a drilling tool for the purpose of regrindihg.

The anchoring operation described above can be performed working quickly and at low cost, since only a few/steps are necessary, especially if a rotary percussion drill is used. The hole is drilled in one operation by. means of a Bhank held i the chuck of a rotary percussion drill, for example, and by means of an expanding wedge with cutting edges detachably fitted thereto, whereupon the shank is withdrawn from the expanding wedge remaining in the hole. The f stening element is then anchored in the hole in that its expanding end portion is driven onto the expanding wedge. In this way, the bolt-like stening element is anchored in a working operation comprising only a few steps. The beet possible fastening action is achieved if the bolt-like fastening element of the invention has a diameter corresponding to the diameter of the hole. -10- 34181/2 "·>\

Claims

CLAIMS An expansion element for anchoring a wall plug in a hole in a the expansion element being provided at one end with cutting edges constituting a drill tip and having a wedge portion expanding the wall An expansion element claimed in Claim whic can be detachably connected to a drill An expansion element as claimed in Claim in which one or more projections is or are provided on the wedge the projections extending substantially longitudinally of the expansion element and away from the drill the projections being in recesses of the shank to prevent relative rotation between the shank and the expansion An expansion element as claimed in Claim in which the matching of the shank merge with helical flutes provided therein for the discharge of boring recesses running parallel with the axis of the shank in the region at which the projections of the expansion element are An expansion element as claimed in

1. Claim 1 or which comprises an elongated flat An expansion element as claimed in Claim in which that end of element remote from the drill tip ca be inserted into a slot formed in the end of a shank to connect the shank and the element together and prevent relative rotation An expansion element as claimed in Claim in which a longitudinally extending projection is provided on two opposite lateral surfaces of the expansion the projections being displaced in diametrically opposite directions from the axis of the expansion An expansion element as claimed in Claim in which the projections are engageable with recesses formed at diametrically opposed side edges of the slot of the drill An expansion element as claimed in Claim or in which the projections have convex An expansion element as claimed in any one of Claims 1 to in which the wall plug also functldns as the drill Λ combination of a wall plug and an expansion element as claimed in any one of Claims 1 to combination as claimed in Claim in which the wall comprises a polygonal hollow rod twisted about its longitudinal with retaining means at one end and a longitudinal slot at the other the slot widened towards this other end in a stepwise A method of anchoring a wall plug in a bore in a comprising the steps of attaching the expansion element of Claims to a drill drilling a hole in a detaching the shank from the expansion element which latter remains in the drilled hole and introducing the wall plug into the hole so that it is expanded by the expansion element to grip the walls of the A method as claimed in Claim in which the wall plug al30 constitutes the drill the wall plug being provided with engagement with the expansion element during the wall plug being detachable the expansion element so that when the hole is the wall plug can be rotated relative to the expansion element and can then be pushed into engagement with to be expanded into contact with the walls of the An expansion element substantially hereinbefore described A method of anchoring a wall plug in a in a wall substantially as hereinbefore For the Applicants insufficientOCRQuality