GB2077385A

GB2077385A - Expansible fastening plug for masonry

Info

Publication number: GB2077385A
Application number: GB8115651A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-06-02
Filing date: 1981-05-21
Publication date: 1981-12-16
Also published as: ES258546Y; DE3020907A1; AT380315B; DK230581A; DE3020907C2; ES258546U; IT8121898A0; BE888636A; GB2077385B; NL8101971A; IT1138789B; BR8103433A; ATA173681A; FR2483543A1

Abstract

A fixing plug (2) with an internally or externally threaded end for achoring in a masonry bore (8) which is widened outwards (9) at its bottom end, is tubular and its bore 3 tapers sharply in the anchoring portion 4, so that when an expansion pin 6 with a rounded end (7) is driven into the plug bore it engages the tapered part (4) of the plug bore to expand the anchoring portion into the widened portion (9) of the masonry bore. <IMAGE>

Description

SPECIFICATION Fastening equipment for masonry This invention relates to fastening equipment.

Known fastening equipment comprises an impact-expansible plug for anchoring in cylindrical boreholes in masonry, the plug having an expansible sleeve with an outer and/or inner thread for receiving a fastening bolt and an expansion pin which can be driven into a tapered portion of the inner bore of the expansible sleeve.

To facilitate driving of the expansion pin into the tapered portion of the plug bore, the pin is pointed and the tapered portion is very slightly tapered.

Although, in this case, expansion of the sleeve is relatively slight it is sufficient to brace the plug in the borehole. There are, however, certain cases where such tensioning of the plug to effect anchorage is undesirable or even disadvantageous. In these cases effective anchorage can be achieved only by enlarging the borehole conically at its base and arranging for greater expansion of the plug into that enlargement so that the plug is positively anchored therein.

In this way the resistance to withdrawal of the anchored plug is much greater (owing to its larger expansion and the positive anchoring effect) and consequently, the equipment can provide a satisfactory anchor whatever the nature of the masonry and even if cracks are present in the masonry bore.

An object of the present invention is to provide fastening equipment the plug of which can be anchored in a borehole which is outwardly widened at its bottom end and which can be expanded to a greater extent than plugs used for cylindrical boreholes.

The present invention provides fastening equipment comprising a fixing plug for anchoring in a bore in masonry the bore widening outwards at its bottom end, and an expansion pin, wherein the plug is tubular with an anchoring portion at one end, the bore of the plug sharply tapering in the anchoring portion, the end of the plug remote from the anchoring portion having a screw thread, and wherein the pin has a rounded end which, when the plug is inserted into the masonry bore and the pin is driven into the plug bore, engages the tapered part of the plug bore to expand the anchoring portion into the widened portion of the masonry bore.

To anchor the plug it is inserted into the prepared undercut borehole until its leading end touches the base of the borehole. Depending on the design of the plug, the expansion pin is then driven into the tapered portion of the expansible sleeve either by a separate striking pin or directly by striking the expansion pin itself. Engagement between the rounded end of the pin and the very sharply tapered part of the plug bore results in a very pronounced expansion of the anchoring portion of the plug.

If, as is preferred, the anchoring portion has an axial slot dividing that portion into two parts those parts are moved outwardly and away from each other as the pin is driven in to form a V-shaped wing formation. The wings lie against the wall of the undercut portion of the masonry bore to form a positive anchor.

Engagement between the rounded end of the pin and the tapered portion of the plug bore would not give satisfactory expansion in a cylindrical masonry bore but by providing an undercut in the masonry bore, the wall of that bore offers negligible resistance to expansion of the plug, so that satisfactory anchorage is achieved. The rounded end of the expansion pin also has the advantage that expansion of the plug and bracing of it in the masonry bore is achieved by an untapered or full diameter portion of the pin.

It is of advantage, when the screw thread is an internal screw thread, if the length of the pin is equal to the total length of the plug less at least part of the length of the screw-threaded portion of the plug so that a bolt can be screwed into that portion, when the pin has been driven into the plug, to hold an article against the masonry. In this way it can be made impossible, in the event, for example, of improper expansion of the plug, for an object to be fastened by means of the bolt since if the pin is not driven sufficiently far into the plug there will be insufficient depth of screw thread to hold the bolt.

It is also of advantage, when the screw thread is an external screw thread if the length of the expansion pin corresponds to the total length of the plug. In this way, a visual check on whether the plug has been anchored correctly is provided since that will be achieved when the end of the pin, opposite its rounded end, is level with the end of the plug remote from the anchoring portion.

The present invention also provides an impactexpansible plug for anchoring in boreholes that are enlarged conically towards the inside, consisting of an expansible sleeve having an outer and/or inner thread for fastening objects and an expansion pin which can be driven into the narrowing inner bore of the expansible sleeve, characterised in that the end of the expansion pin opposite its striking end is rounded and the narrowed part of the inner bore of the sleeve is very sharply tapered.

Two forms of fastening equipment constructed in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings in which: Fig. 1 shows a first form of fastening equipment with its plug in its non-expanded condition, Fig. 2 shows a second form of fastening equipment with its plug in its non-expanded condition, and Fig. 3 shows the equipment of Fig. 1 with the plug in its expanded condition.

Referring to the accompanying drawings and first of all to Fig. 1 the equipment comprises a tubular fixing plug 2, which can be made of metal or injection molded from plastics material, which has an internal screw thread 1 at one end and which has an anchoring portion having an axial slot 5 at the other end. The bore 3 of the plug 2 sharply tapers in a region 4 within the anchoring portion. The equipment also comprises an expansion pin 6 which has a rounded insertion end 7. To anchor the plug 2 in a bore 8 in masonry the pin 6 is driven into the bore 3, engagement between the rounded end 7 and the tapered bore portion 4 expanding the anchoring portion. The slot 5 divides the anchoring portion into two parts which are forced away from each other by the pin to form wing-like retention members.The end portion of each of the anchoring parts has a wall thickness at least double that of the remainder of the plug so that expansion of those parts is considerable. Expansion of the anchoring portion is facilitated by providing weakened portions, for example by providing small recesses as shown, in the wall of the plug.

Because expansion is achieved by engagement between the rounded end 7 of the pin 6 and the very sharp taper 4 of the inner bore 3, it would not be possible -- because the driving-in resistance would be too high - to effect expansion of the plug in a cylindrical bore. For that reason, the masonry bore 8 has an outwardly widened or undercut portion 9 at its bottom end which effectively reduces the resistance to insertion of the pin in the plug.

Before the plug is anchored, the striking end (that is to say, the end opposite to the rounded end 7) of the expanding pin 6 is approximately level with the screw-threaded end of the plug. The striking end in fact lies slightly within the threaded end of the plug to facilitate positioning of a striking tool 1 0. After the plug has been anchored the expansion pin 6 leaves at least the major part of the thread 1 free so that a fastening bolt or screw 11 can be engaged with it (see Fig. 3). This ensures that an object for example a panel 12 can be fastened to the masonry only when the plug is correctly anchored since otherwise an insufficient portion of the thread 1 will be left free to receive the bolt 11.

The plug of the fastening equipment shown in Fig. 2, has an external screw thread 13. In this case the pin 6 can be driven into the plug without using a striking tool. When the rounded end of the pin 6 engages the tapered portion of the plug bore its other end extends beyond the end of the plug (remote from its anchoring portion). Consequently, the pin itself can be struck to drive it into, and to effect expansion of the plug. If the length of the expansion pin 6 corresponds approximately to the total length of the plug then, when the plug is properly anchored, the end of the pin will be level with the end (remote from the anchoring portion) of the plug which provides a simple check on whether the plug has been anchored correctly.

After anchorage an object, such as a panel, can be braced against the outer surface of the masonry 1 5 by screwing a nut 14 onto the outer screw thread 13.

Claims

1. Fastening equipment comprising a fixing plug for anchoring in a bore in masonry the bore widening outwards at its bottom end, and an expansion pin, wherein the plug is tubular with an anchoring portion at one end, the bore of the plug sharply tapering in the anchoring portion, the end of the plug remote from the anchoring portion having a screw thread, and wherein the pin has a rounded end which, when the plug is inserted into the masonry bore and the pin is driven into the plug bore, engages the tapered part of the plug bore to expand the anchoring portion into the widened portion of the masonry bore.

2. Equipment as claimed in claim 1, wherein the screw thread is an internal screw thread, and the length of the pin is equal to the total length of the plug less at least part of the length of the screw-threaded portion of the plug so that a bolt can be screwed into that portion when the pin has been driven into the plug to hold an article against the masonry.

3. Equipment as claimed in claim 1, wherein the screw thread is an external screw thread and the length of the pin is equal to the total length of the plug.

4. Equipment as claimed in any one of claims 1 to 3, in which the anchoring portion has an axial slot to allow expansion of that portion when the pin is driven into the plug.

5. An impact-expansible plug for anchoring in boreholes that are enlarged conically towards the inside, consisting of an expansible sleeve having an outer and/or inner thread for fastening objects and an expansion pin which can be driven into the narrowing inner bore of the expansible sleeve, characterised in that the end of the expansion pin opposite its striking end is rounded and the narrowed part of the inner bore of the sleeve is very sharply tapered.

6. Fastening equipment substantially as hereinbefore described with reference to, and as shown in Figs. 1 and 3 or Fig. 2 of the accompanying drawings.