IL32353A

IL32353A - Wall plugs

Info

Publication number: IL32353A
Application number: IL32353A
Authority: IL
Original assignee: Fischer Artur
Priority date: 1968-06-08
Filing date: 1969-06-06
Publication date: 1972-04-27
Also published as: IL32353A0; IE33098L; BE734191A; CS166157B2; GB1263557A; CH495476A; FR2024604A6; ES172826Y; SE350809B; NL6908406A; NO128581B; RO54824A; IE33098B1; ES172826U

Description

32353/2 Wall Plugs ABTUR FISCHEH C. 30321 This invention relates to wall plugs for anchoring in a hole in a wall and comprising a bolt and an expanding sleeve, whose cooperating parts are conical.

Wall plugs of this type are known, e.g. from British Patent Specifications 897»594 and 935,761 and U.S. Specification 3,241,428.

This known arrangement does not give full satisfaction, as little as do those known wal plugs in which the bore of the sleeve has uniform diameter throughout. With these known wall plugs, the effective anchoring in hard stone or concrete is often difficult or impossible. When the bolt is turned the sleeve is pulled towards the conical portion of the bolt and expands when engaging the latter, parts of the sleeve normally tend to penetrate into the wall of the hole as the shank continues to be turned. However, hard stone or concrete offer a very high resistance to such penetration, so that there is a risk that the thread of the bolt win jump the thread of the sleeve, which would prevent the sleeve from being pulled completely onto the conical portion of the bolt. The sleeve could also suffer longitudinal compression, which would produce bulges running around the sleeve. As a result, friction would be impaired because there would be no uniform pressure in the region of the sleeve surface. Moreover, these bulges may stretch again when the shank is subjected to tensile stress, so that whatever anchoring effect had been achieved would thus be cancelled. furthermore, the bolt is of larger diameter in the non-threaded region than in its threaded region, or it is reinforced in this region by an additional sleeve. However, — — which is determined by its smallest cross-section in the threaded region. In the case of an effectively anchored wall plug, the pulling forces may he so large that they exceed the strength of the bolt. Yet, the added strength of the thickened bolt portion cannot be exploited. Owing to its thickened bolt portion, the known wall plug is more expensive without offering the advantage of added strength.

According to the present invention a wall plug comprising a bolt and an expandible sleeve, both bein formed with cooperating conical portions of differing conicities and the conical portion of the bolt being formed with a screw-thread of substantially constant depth, characterised in tha the originally not-tapped conical portion of the sleeve is Of greate conicity than the conical portion of the bolt and that the screw-thread of the bolt is sawtooth-shaped, the thread flanks extending at right angles to the longitudinal axis of the bolt and facing away from the conical end of the bolt.

When the bolt is screwed into the sleeve, the thread portion of the bolt taps its counter-thread in the inner conical portion of the sleeve. Owing to the difference in cone angless the thread of the conical portion of the bolt at first engages the sleeve onl at one point where the sleeve expands strongly. The friction between the bolt and sleeve at first remains lower than between sleeve and bore, while the sleeve becomes anchored more firmly and cannot rotate.

As the shank continues to be screwed in, its conical portion graduall engages the inner conical portion of the sleeve over its entire length. Application of the sleeve to the inner surface of the bore-hole with uniform pressure is ensured and onitudinal comression avoided. Since there is stron pressure between sleeve and bolt in the threaded region, individual threads cannot be missed while the screw turns* She shank can be firmly tightened and the component to be fastened to the wall can therefore likewise be firmly clamped* Finally, a firm connection between bolt and sleeve is achieved. Therefore, the tensile strength achieved in the region of the sleeve is only slightly lower than the tensile strength in the remaining shank portion. iUhe wall plug according to the invention is simple to manufacture. For example, the bolt may be of a commercially available kind with threaded head or hexagonal head provided at its leading end with a threaded conical portion, for example by cold extrusion. Bolt and sleeve may be distributed as a single element. All that is necessary is a slender screw-connection between sleeve and threaded bolt. A quarter-turn may be suf icient to provide a temporarily connected unit suitable for transportation.

Given a shank and a sleeve of equal external diameter, as is known per se, the conical portion of the bolt must be longe than the conical portion of the sleeve, he bolt may therefore penetrate far into the sleeve without parts of the latter having to penetrate into the wall of the hole. With concrete or hard stone, such penetration would be difficult and longitudinal compression of the sleeve might have to be anticipated.

Preferably, a cylindrical cavity is provided adjacent tie narrow end of the conical portion of the sleeve, fhis facilitates engagement of the thread of the tolt with the sleeve in the region of an edge produced by this formation of the sleeve Since the conical portion of the bolt is provided at that end which, in use, projects into the hole* for cooperation with the sleeve, there are no parts of the bolt which project beyond the sleeve in the longitudinal direction of the latter, .therefore, the hol need not be deeper than is necessary for direct anchoring. Also the sleeve itself can now apply itself to the bottom of the hole. It is possible for the bolt slightly to project beyond the sleeve after having been screwed into the latter. However, since the hole is usually drilled it is of conical formation at the bottom, and so sufficient space for the tip of the bolt is usually available in this conical cavity.

In order that the thread should be capable of absorbing large tensile forces it may be sawtooth-shaped in such a way that the flanks of the thread extend at right angles to the longitudinal axis and face away from the tip of the bolt.

The sleeve may be made from a synthetic resin or a readily yielding metal such as aluminium or zinc alloy. In the latter case the sleeve may be provided with a slot, which extends preferably over its entire length, in order to ensure satisfactory expansion, 9?o improve the temporary anchoring of the sleeve as a safeguard against rotation, the sleeve may be provided on Its outer circumference with resiliently yielding or with firm but deformable anti-rotational locking means, as known per se. f ey are preferably used when the plug is to be inserted in porous material. She yield when the sleeve with the bolt is inserted in a hole drilled in masonry, but ma of - of the hole, thus preventing rotation. In firm, hard materials such as concrete, irm hut deformable locking means are especially suitable. While the sleeve is inserted in a prepared hole, the locking means are deformed and, owing to the resistance they offer to deformation, the sleeve is wedged in the hole. In this way, also this type of locking means provides an anti-rotational safeguard. ¾he locking means may be, for example, tongues provided in the region of the sleeve end adjacent the narrow end of its conical portion and so that they extend towards the other end of the sleeve in longitudinal sleeve direction, as well as in a radial direction away from the outer sleeve circumference, or longitudinally extending ribs arranged on the outer sleeve circumference, preferably moulded therewith during manufacture, provided in the region where the conical portion of the bolt first makes contac with the conical portion of the sleeve. It is in this region that the sleeve first starts to expand, so that the ribs are immediately urged against the inner surface of the hole and thus improve the anti-rotationa effect* fiowever, the same purpose may also be served in that the cross-section of the inner surface of the oonical portion of the sleeve, in the region of its narrow end, assumes an abnormal shape departing from the circular shape of the remainder of the cone. 3?his abnormal shape is preferably rectangular. Or the abnormal shape may be achieved by longitudinally extending, short ribs distributed oyer the inner circumference, Any othey shape, e.g. triangular or oval, is also feasible. The transition from the circula to the abnormal shape may be either gradual or sudden.

Own a ae n e e o he conical portion of the bolt engages the sleeve at first only in a few points. Thus, the friction between the bolt and sleeve at first remains lower than between sleeve and bore, owing to the small area of contact. The rotation of the expanding sleeve is thus avoided. After only a few turns the sleeve will have expanded strongly whereby it is increasingly safeguarded against rotation. As the bolt is turned in further, it engages the sleeve with its entire thread and expands the latter over its entire length.

If the sleeve is provided with a slot, which preferably extends over its entire length, and the sleeve has a cross-section of rectangular shape in the region of the narrow end of its conical portion, the short side of the rectangle preferably extends in the direction perpendicular to the plane of the slot. The greatest displacement of sleeve material, and thus the greatest expansion of the sleeve facilitat ed by the slot, will then occur in a direction at right angles to the plane of the slot.

Advantageousl f the bolt is provided with stop means for fixing a component to the wall. A compressible intermediate element may be inserted between the stop means and the component to be fastened to the wall, the thickness of this intermediate element, measured in the longitudinal direction of the bolt corresponding to the amount by which the bolt can be made to penetrate into the sleeve to become anchored therein.

When a component is to be fastened to a wall, the bolt is inserted in a pre-drilled hole, provided in the component as well as in the wall, sufficiently far for the above-mentioned intermediate element to bear on the surface of the component. When the bolt is turned, it is screwed - - the wall, the component will also have become clamped to the wall. The deformable intermediate element thus ensures that the component is in fact clamped firmly to the wall once the bolt has become completely anchored. This result is ensured because, owing to the intermediate element, the bolt always moves towards the component through the same distance. This distance corresponds to the distance through which the bolt has to be screwed into the sleeve in order to achieve optimum expansion. The employment of an intermediate element is recommended especially where the stop means is positively connected to the bolt. However, the intermediate element may also be employed when this stop means is longitudinally displaceable relative to the bolt* The intermediate element may be cup-shaped, the rim of the cup being deformable in an outward direction so as become situated in the same plane as the cup bottom. After deformation, the intermediate element may then also serve as a washer. Depending upon the material used, it may also serve as a gasket.

As described below the invention is particularly Suitable for a wall plug including a bolt having a conical portion that tapers towards that of its ends which, in use, projects into a hole in a wall.

The invention is illustrated,, by way of example, in the accompanying drawings, in whichs Figure 1 shows a section of a wall plug; Figure 2 shows, in s c ion, the tip of a wall plug of different design? Figure 3 shows,, in plan view the narrow end of the sleeve of the wall plug of Figure 2f and Figure 4 shows an expanding sleeve with locking tongues.

Figure 1 shows a wall 1 in which a hole 2 has been drilled. A holt 3 is inserted into the hole 2» the end of the holt 3 projecting beyond the wall 1 being provided with a hexagonal head 4 acting as a stop means, The other end of the bolt 3 which projects into the hole 2 has a conical portion 5 tapered towards this end. It is provided with a saw-toothed thread 6 comprising flanks 7 which extend at right angles to the longitudinal axis of the bolt 3 and face away from the end inserted into the hole 2. An expandible sleeve 8 is slipped onto the conical portion 5, the sleeve having an inner conical surface 9 narrowing in the same direction as the conical portion 5. The angle of the inner conical portion 9 of the sleeve.8 is larger than that of the conical portion 5 of the bolt 3f Therefore, the conical surface 5» prior to the expansion of the sleeve 8, at first bears on the inner conical portion 9 of the sleeve 8 only in the region of the largest croes-section of the latter. This largest cross-section of the sleeve 8 merges into a cylindrical portion 10 which forms an edge H with the inner conical portion 9. This edge 11 facilitat the engagement of the saw-toothed thread 6 of the conical portion 5 of the bolt 3. The sleeve 8 is slotted over its entire length* In the region of the edge 11, the sleeve 8 is provided on its outer circumference wit shor , longitudinally extending ribs 12 which project beyond the outer circumference and constitute an improved anti-rotational safeguard. Before the expansion of the sleeve its outer diameter Is equal to that of the bolt, which makes possible the use of the wall plug by the push-through method.

Between the hexagonal head 4 and an object 13 to be fastened to the wall 1 there is arranged a deformable cup-shaped intermediate element 14. It may consist of synthetic plastics material, for example, measured in the longitudinal direction, the thickness of the deformable part of the intemediate element 14 corresponds to the amount by which the bolt 3 can be screwed into the sleeve 8 for the purpose of becoming anchored therein. When the bolt 3 is screwed into the sleeve 8 the rim 15 of the intermediate element 14 yields in outward direction. The element 14 thus turns into a washer which may also serve as a gasket, depending upon the material used. £he element 14 may also be of different shape, as long as deformation to the above-* mentioned degree remains possible. It may be integral with the hexagonal head 4» or it may be subsequently combined therewith.

In figures 2 and 3» inner conical portion 9 o the sleeve 8 is extended by a narrow bore 16 of the inner surface of rectangular cross section. The sleeve 8 has a slot 17 extending over its whole length.

Figure 4 shows a sleeve 8 having on its outer circum* ference two diametrically opposite recesses 18. Moulded integrally with the edge 20 of these recesses 18, which edge is adjacent the end 19 of the sleeve 8, are locking tongues 21 which in use engage the walls of a hole 2 to inhibit rotation of the sleeve 8.

Claims

32353/2

1. A wall plug comprising a bolt and an expandible sleeve, both being formed with cooperating conical portions of differing eonicities and the conical portion of the 'shank bolt being formed with a screw*?thread of substantially constant depth, characterized in that the originally not-tapped conical portion of the sleeve is of greater confc&eity than the conical portion of the bolt and that the screw-thread of the bolt is sawtooth-shaped, the thread flanks extending at right angles to the longitudinal axis of the bolt and facing away from the conical end of the bolt,

2. A wall plug as claimed in Claim 1, in which the sleeve comprises resiliently yielding or firm but deformable locking means provided on its outer circumference for securing it against rotation, e.g. tongues provided in the region of the end of the sleeve adjacent the narrow end of its conical portion and extending towards the other end of the sleeve in the longitudinal direction of the sleeve, as well as in a radial direction away from the outer sleeve circumference, or longitudinally extending ribs arranged o the outer circumference of the sleeve in the region of the area where the conical portion of the bolt first makes contact with the conical portion of the sleeve.

3. · A wall plug as claimed in Claims 1 or 2, in which the sleeve is formed, at the narrow end of its conical portion, with a cavity of rectangular transverse cross-section.

4. * A wall plug as claimed in Claim 3, in which the short side of the rectangle extends at right angles to the plans of the slot. 32353/2 12 -

5. A wall plug aa claimed in Claims 1 or 2, in which the narrowest part of th© internal surface of the conical portio of the sleeve merges with a cylindrical cavity,

6. A wall plug as claimed in any one of Claims 1 to 5» in which the holt is provided with stop means or ixing a component to the wall.

7. · A wall plug as claimed in Claim 6, in which a compressible intermediate element is inserted between the stop means and the component to be fastened to the wall, the intermediate element having a thickness, measured in the longitudinal direction of the shank, which corresponds to the amount by which the bolt can be screwed into the sleeve for the purpose of anchoring.

8. A wall plug as claimed in Claim 7, in which the intermediate element is cup-shaped, the rim of the cup being outwardly deformable until it becomes situated in the same plane as the bottom of the cup.

9. An expansion bolt as claimed in any of Claims 1 to 8, in which the outer diameter of the sleeve is the same as the diameter of the shank,

10. An expansion bolt substantially as hereinbefore described with reference to, accompanying drawings. RC:CB