EP0178277B1

EP0178277B1 - A fastener device which functions as a rock dowel

Info

Publication number: EP0178277B1
Application number: EP85850318A
Authority: EP
Inventors: Erik Marcus Lindblom
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-10-09
Filing date: 1985-10-09
Publication date: 1989-03-15
Also published as: SE8405038D0; EP0178277A3; ATE41313T1; DE3568703D1; EP0178277A2; SE8405038L; SE454051B

Abstract

A fastener device (1) which functions as a rock dowel and intended for use in rock climbing or for mooring boats, and the like, comprising a first element (2) and a second element (5) which are integrated with one another at a juncture (12). The first element (2) has the form of a wedge intended for co-action with a crack (3) in a rock surface or like surface, and the second element (5) forms an attachment for a line (8) or the like (7). The first element (2) is twisted in its longitudinal axis relative to a central plane (10) extending through the first element (2) from the juncture (12) at the second element (3).

Description

Technical field

The present invention relates to a rock dowel device, and more specifically to a device which can be used for rock climbing, mooring boats, and like purposes, and which comprises a first and a second element which are integrated one with the other. The first element has the form of a wedge for insertion, for example, into a crack in rock face, and the second element forms an attachment for a rope, chain or like line.

Background prior art

Such rock dowel devices are known to the art in various forms, as in FR-A-900663.
In another known embodiment of such devices the first element has the form of a flat wedge intended for insertion into a crack in the rock face, or some other form of opening in some other surface, as in CH-A-253276.
Various types of wedge-shaped implements having an element twisted about its longitudinal axis are known, for example for splitting logs, in which the wedge part has the form of a single member and the wedge tip or point is twisted 10° in relation to a geometric central plane.
Such wedges have a large hammering or anvil surface at one end thereof and the wedge angle is quite large, for example larger than 10° but smaller than 15°. Such wedges are practically totally inelastic.
In DE-C-105832 the element is twisted for securing a tent wall, in US-A-3025853 the element is twisted for fixation of a fractured femur and in DK-A-55377 the element is twisted for cooperation with wooden materials.
Consequently, twisted elements, which are intended for splitting logs etc. are not suited for use in conjunction with rock dowel devices for rock climbing or for mooring boats to rock surfaces.
With respect to prior art rock dowel devices of the aforesaid kind, attachment of the device via the first element is effected exclusively through direct counter-directional clamping forces, in which a planar wedge surface is pressed against one wall of the crack, and the opposite planar wedge surface is pressed against the opposite wall of the crack. Any deformation which might occur is caused through the action of counterdirected forces acting on the same part or point on the wedge.
It has been found that in order to use such a wedge effectively the crack into which it is driven should have a width which more or less equals the maximum width of the wedge or which is slightly smaller than said width, and that the crack should be quite deep and preferably have a shape which conforms to the shape of the wedge.
Moreover, once driven into an ideal crack, the prior art fastener device is extremely difficult to remove therefrom.

Disclosure of the present invention

Technical problems

With reference to the present state of the art beforedescribed it will be seen that one qualified technical problem resides in the provision of such rock dowel devices which can be reliably secured in a crack the width of which exceeds the maximum thickness of the wedge and/or whose configuration deviates from the configuration of the wedge.
Another technical problem resides in the provision of such a rock dowel device with which the wedge-shaped element thereof can be subjected to torque such as to be brought into gripping co-action with mutually oppposite walls of a crack, this torque causing diametrically opposed wedge edges to grip against said crack walls.
Another technical problem resides in the provision of such a rock dowel device so formed as to provide a reliable grip through the action of a large, substantially calculatable force, by observing material deformation caused by forces over and above the elastic deformation limit of the material and lying within the plastic deformation range.
With regard to the prior state of the art as described above, it is seen that a further qualified technical problem is one of providing a device of the kind intended for rock climbing mooring boats to rock surfaces etc., with which the wedge-like first element of the device when inserted, for example, into a crack in a rock surface strives to engage the crack walls and to conform to the contours of the crack, such as provide good contact between diametrically opposed wnd outwardly facing edge parts of the first element and the two engaging wall surfaces of the crack.
Still a further technical problem is one of providing such a device with which the diametrically opposed, outwardly facing edge parts of the first element co-acting with opposite walls of a crack can be brought into positive and reliable engagement therewith and readily released therefrom in a simple manner.
Another technical problem is one of providing means whereby the aforesaid co-action between the wedge-like first element of the device and the walls of a crack can be effected with the aid of torque or torsional forces acting in the material of the wedge-like element, between two outwardly facing and mutually opposite edge parts thereof, so that the wedge will grip firmly in the crack through the agency of such internal forces as those occurring with plastic deformation.
Another technical problem is one of providing such a device which with the aid of simple means can be made to conform more readily to the contours of a crack in a rock surface, such that the configuration of the crack determines the size of the contact surface formed between the two mutually opposed and outwardly facing edge parts, when the pressure forces taken-up shall function as torque on the wedge.

Solution

The present invention relates to a rock dowel device as is known from CH-A-253276, which can be used for rock climbing, mooring boats to rock surfaces, etc., which device includes a wedge-shaped first element for co-action with the walls of a crack in a rock surface, and a second element which is integrated with the first element and which forms an attachment for a rope, chain or the like.
In accordance with the invention the first element is twisted about along its longitudinal axis.
Further significant features of the shown embodiment are stated in the subclaims.

Advantages

Those advantages primarily afforded by a rock dowel device constructed in accordance with the invention reside in the possibility of inserting the device into a crack in a rock surface, or like surface, and to obtain a firm and reliable grip therein even when the width of the crack exceeds the width of the fastener device, and also in the fact that the securing or fastening forces generated are substantially in the form of torque acting on said device, thereby to facilitate entry of the device into the crack and reliable retention of the device therein. In addition, the securing or gripping forces can be readily regulated to a desired level, and the device can be readily removed from the crack with the aid of simple means.

Brief description of the drawing

Exemplifying and preferred embodiments of the invention will now be described in detail with reference to the accompanying drawing, in which

Figure 1 is a perspective illustration of a rock dowel device according to the invention inserted in a crack in a rock surface;
Figure 2 is a perspective illustration of solely the device shown in Figure 1, and illustrates the twist in the first element; and
Figure 3 is a view of an alternative embodiment, similar to the illustration Figure 2.

Description of embodiments at present preferred

In Figure 1 there is illustrated in perspective a rock dowel device 1 for use in rock climbing and which can also be driven into rock surfaces in waterside locations to facilitate the mooring of boats. The dowel device 1 comprises a first element and a second element which is integrated with the first element. The first element 2, which has a wedge-like configuration is intended to grip against the walls of a crack 3 in a rock surface 4 or like surface. The second element 5 forms an attachment means for a rope, chain or like line. To this end, the second element 5 is provided with a hole 6 in which a ring 7 is held. Attached to the ring is a line 8, which may either be tied to a climber or to part of a watercraft, depending on the use to which the device is put. When the device is used to secure a boat to a rock at the water's edge for example, the line 8 can be caused to extend substantially horizontally.
It will be understood that the first element 2 need not be constructed to exert a wedge-action along the whole of its length.
Suitably, the wedging-form of the first element 2 only extends a short distance from the tip or point 11 of said element along towards the second element 5, with the remainder of the first element being of more or less right-angled constant cross-section therealong.
Irrespective of the configuration or form of the first element 2, the wedge-angle from the juncture region 12, adjacent the second element 5, to the tip or point 11 should be less than 5°, preferably between 3° and 4°.
A device in which the wedge form of the first element 2 extends along roughly 25% of the total length of said element, with the remainder of the element having a constant cross-section, has been found particularly suitable.
The first element 2 may suitably be made of a material which, with a cross-sectional size of 6x18 mm and a length of 25 mm, will result in the plastic deformation of the element at a torque of 120 Nm. In this respect, variations between 80 and 200 Nm can be accepted.
As shown in the drawing, the first element 2 is twisted about its longituidinal axis which axis is positioned in a central plane 10 extending along the first element from the juncture 12 of its connection with the second element 5, so that one part of the first element is rotated relative to an adjacent part.
As beforementioned, the ring 7 and line 8 have been omitted from Figure 2, for the sake of clarity.
Thus, in the illustrated embodiments, the top or point 11 of the first element 2 is rotated through an angle "a" in relation to the central plane 10 of at least 30°. It will be understood that the tip 11 may be rotated relative to plane 10 through any angle, up to 360°. Preferably the angle "a" lies between 45° and 180°, and then most suitably between 60° and 120°. In the Figure 2 embodiment, the tip 11 has been rotated through 90° in relation to the central plane 10.
The first element 2 is made from a material such that when brought into gripping action with the mutually facing wall portions 3a and 3b of the crack 3, the element can be subjected to plastic deformation, which means that subsequent to driving the first element 2 into the crack 3 (hammering the device), the said element will be permanently deformed when removing the device from the crack 3. It is especially proposed that the device is driven into the crack 3 with such force and in such a manner that the element 2 does in fact become deformed plastically, since such plastic deformation signifies that the material in the first element 2 is used to a maximum in creating those torsional forces which shall hold the first element 2 firmly in the crack 3.
It is sufficient if this plastic deformation is only manifested along given sections of the first element 2.
The gripping forces exerted by the first element 2 on the crack walls 3a and 3b act through the diametrically opposed edges 13 and 14. In combination with the fact that one edge 13 or 14 forms an engagement point or edge surfaces against a respective wall-portion of the crack.
As will be seen from Figure 2, the first element 2 of the device has a thickness which narrows only slightly towards the tip or point 11 of said element.
The first element 2 may also be shaped so as to present a width which decreases, albeit but slightly, towards said tip or point 11, as illustrated particularly in Figure 3.
The second element 5 of the device 1 may be given a hardness which is greater than the hardness of the first element 2, since the first element 2 shall be capable of being plastically deformed, whereas the second element 5 must be capable of withstanding the impact forces to which it is subjected when driving the first element 2 into the crack 3, and of withstanding the load on the line 8 without being deformed.
In the embodiment illustrated in Figure 3 only a part of the first element 2 has been twisted, namely the part 2a, and the remainder, 2b, of said element is flat. In addition, the twisted part 2a of the first element 2 of the Figure 3 embodiment is located in the vicinity of the juncture of the first element 2 and the second element 5.
With a device constructed in accordance with the present invention it is possible to ascertain visually, when the wedge-like first element 2 is driven or hammered into the crack 3, that the material in said element has been loaded to a point above the elastic limit of said material, therewith guaranteeing that a lowest permitted gripping force has truly been exceeded.
Since the gripping forces concentrate at the edges 13 and 14, a strong and secure grip is achieved when a load is applied in the direction of the line 8. When wishing to remove the wedge-like first element, it is simply pulled straight out of the crack.

Claims

1. A rock dowel device intended for use in rock climbing or for mooring boats, and the like, comprising a first element (2) and a second element (5), which are integrated with one another at a juncture (12), the first element (2) having the form of a wedge, intended for co-action with a crack (3) in a rock surface or like surface, and the second element (5) forming an attachment for a line (8) or the like (7), characterized in that the first element (2) is twisted about its longitudinal axis.

2. A device according to Claim 1, characterized in that the tip (11) of the first element (2) is rotated through an angle of at least 30° in relation to a central plane (10).

3. A device according to Claim 1 or Claim 2, characterized in that the tip (11) of the second element (2) is rotated relative to the central plane (10) through an angle of at most 360°.

4. A device according to Claim 1, 2 or 3, characterized in that the tip of the first element (2) is twisted in relation to the central plane (10) through an angle between 45° and 180°, preferably between 60° and 120°.

5. A device according to Claim 1, 2, 3 or 4, characterized in that the first element (2) is made from a material which tends to become plastically deformed when said first element is in gripping contact with the walls of the crack (3).

6. A device according to Claim 1, characterized in that the first element (2) has a thickness which decreases but slightly down towards the tip (11) thereof.

7. A device according to Claim 6, characterized in that the first element has a width which decreases but slightly down towards the tip (11) thereof.

8. A device according to Claim 1, characterized in that the second element has a hardness which is greater than the hardness of the first element.

9. A device according to Claim 1, characterized in that only a part (2a) of the first element is twisted.

10. A device according to Claim 9, characterized in that only that part of the first element located closely adjacent the second element (5) is twisted.

11. A device according to Claim 1, characterized in that the first element (2) has a length/cross- section ratio of 5-15/cm and a wedge angle smaller than 5°.