AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT ORIGINAL Name of Applicant: Hilti Aktiengesellschaft Actual Inventors: Wolfgang Ludwig and Michael Bayerl and Taenzer Lars Address for Service is: SHELSTON IP 60 Margaret Street Telephone No: (02) 9777 1111 SYDNEY NSW 2000 Facsimile No. (02) 9241 4666 CCN: 3710000352 Attorney Code: SW Invention Title: FASTENING ELEMENT FOR USE IN MINING AND TUNNEL CONSTRUCTION The following statement is a full description of this invention, including the best method of performing it known to me/us: File: 64034AUP00 la Fastening element for use in mining and tunnel construction Field of the Invention The invention concerns a rod-shaped fastening element for use in mining and tunnel 5 construction. Background of the Invention Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common 10 general knowledge in the field. In mining and tunnel construction the roof and lateral walls are secured on the rock sections already passed by means of chemically or mechanically anchored rod-shaped fastening elements. Such fastening elements are also described as rock anchors. A rod 15 shaped fastening element has, for example, a solid or hollow, for example tubular, cross section and has, for example, a round or polygonal external periphery. In coal mining, for example, the so called longwall support is used, whereby the fastening elements, securing the lateral walls, are destroyed or cut during the mining of 20 the coal by mining machinery, such as a coal plough. The mined coal, together with the pieces of the fastening elements produced during the mining, is conveyed upward by conveyor belts. The pieces of the fastening elements, remaining in the coal, reduce the quality of the coal. Therefore these pieces must necessarily be removed. In addition, the pieces of the fastening element in the coal impede transport of the coal by the conveying 25 equipment. WO 03/058032 Al suggests the use of a tubular fastening element, formed preferably from steel, as fastening element in mining and tunnel construction for the securing of the lateral walls and to remove the pieces of the fastening element produced 30 during the mining of the coal from the mined coal by means of a magnet. This document also describes experiments with fastening elements for use in mining and tunnel construction made from plastic material with admixed steel fibres as 2 magnetic elements and additionally explains that these experiments with respect to the removal of the elements by means of a magnetic separator were not successful. One disadvantage of the solution mentioned is that the sharp and/or bent pieces of 5 the fastening element can damage the conveyor belts. In addition, steel fastening elements, even if they have thin walls, typically damage the cutting element of the mining equipment. EP 0 014 426 Al discloses a fastening element, made from fibre-reinforced plastic 10 material for the use in mining and tunnel construction. Such fastening elements can be easily severed and without much damage to the cutting element of the mining equipment. It is, however, a disadvantage of this known solution that the sorting out of separated pieces of the plastic fastening elements from the mined coal is time consuming, 15 as the sorting is carried out mostly by hand. A fastening element is known from GB 2 294 658 A, that has a core formed from steel fibres, the core being enveloped by a fibre-reinforced plastic sheath. When compared with a steel fastening element, a fastening element of this kind can be more 20 easily severed by mining equipment, such as a plough to mine the coal, while the cutting element of the mining equipment is subjected only to a slight reduction in wear. A disadvantage of this fastening element is that not all of the separated pieces of the fastening element can be simply removed, for example by a magnet, from the mined coal. 25 Some of the pieces remain in the coal and consequently the quality of the coal is diminished. In addition, the transport of the mined coal on the conveyor belts can be further hindered by the single pieces of the fastening element remaining in the coal. It is an object of the present invention to overcome or ameliorate at least one of the 30 disadvantages of the prior art, or to provide a useful alternative. Advantageously, the invention in at least one preferred embodiment produces a fastening element for use in mining and tunnel construction, in particular for coal mining, that can be removed almost entirely from the mined coal by relatively simple means.
3 Summary of the Invention According to the invention there is provided a fastening element for use in mining and tunnel construction, the fastening element being formed from plastic material that comprises magnetic elements, wherein the magnetic elements are distributed in the entire 5 plastic material over the cross-section of the fastening element and have a concentration in an outer edge region of the cross-section that is greater than that of an adjacent inner region of the cross-section. Unless the context clearly requires otherwise, throughout the description and the 10 claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to". By virtue of the distribution of the magnetic elements in the entire plastic material 15 and the specifically increased concentration of the magnetic elements in the outer edge region of the cross-section, each section or piece of the fastening element, produced by the mining equipment, such as for example a coal plough, contains a certain amount of magnetic elements. Thus the anchor pieces severed by a mining equipment, can be simply removed with a magnetic separator from the mined coal. At the same time the fastening 20 element can be severed by the cutting element of the mining equipment, advantageously resulting in only slight or no damage to the mining equipment. Furthermore, the separated pieces of the fastening element according to at least one preferred embodiment of the invention do not have any significant sharp edges or bends which would be likely to damage the conveyor belts during the transport of the mined coal. 25 The fastening element is advantageously manufactured from a plastic material so that, when the fastening element is severed by the mining equipment, the fastening element disintegrates into small pieces. 30 The magnetic elements are made, for example, from iron, nickel or cobalt. Attention is drawn to the fact, that in this conjunction under a magnetic material a magnetic, magnetisable and/or ferromagnetic material is understood.
3a The cross-sectional dimension of the outer edge region with the increased concentration of the magnetic elements is advantageously 5-30%, and preferably 10-20%, of the overall dimension of the cross-section. In this manner it will be advantageously 5 ensured that each piece of the fastening element, separated by the mining equipment, has an adequate capability to be magnetised for the removal of these pieces from the mined coal.
4 The concentration of the magnetic elements in the outer region of the cross-section is advantageously 1.2-5 times, and preferably 2-3 times, that of the concentration of the magnetic elements in the inner region of the cross-section adjacent to it. By virtue of the 5 significantly greater concentration of the magnetic elements in the above mentioned region, an easy removal of the separated pieces of the fastening element by a magnetic separator is advantageously ensured. In the centre of the cross-section of the fastening element a central region is 10 provided with a concentration of the magnetic elements that is greater than that of the region of the cross-scction adjacent to it. By virtue of the additional region with a high concentration of the magnetic elements the separated pieces of the fastening element can advantageously be even more reliably and consequently almost completely removed from the mined material by means of a magnetic separator. 15 The cross-sectional dimension of the central region with the increased concentration of the magnetic elements is advantageously 10-40%, and preferably 20-30%, of the overall dimension of the cross-section. Thus it will advantageously be additionally ensured that each piece of the fastening element, separated by the mining equipment, has 20 an adequate capability to be magnetised for the removal of these pieces from the mined coal. The concentration of the magnetic elements in the central region of the cross section is preferably 1.2-5 times, and more preferably 2-3 times, that of the concentration 25 of the magnetic elements in the region of the cross-section adjacent to it. By virtue of the significantly greater concentration of the magnetic elements in the above mentioned region an easy removal of the separated pieces of the fastening element by a magnetic separator is advantageously ensured. 30 The magnetic elements are preferably powder, fibres or swarf, that can be simply admixed with the plastic material during the manufacture of the fastening element at the required time and in the required amount. These magnetic elements extend along the entire length of the fastening element, so that the magnetic elements do not hinder the severing of the fastening element by a mining equipment, such as a mine plough.
5 Inserts from a magnetic material are preferably provided in the plastic material. The inserts are advantageously inserted at the required places during the manufacture of the fastening element and positioned there. These inserts extend, for example, only over a 5 section of the total length of the fastening element, so that they have only insignificant influence on the severing of the fastening element. In an advantageous manner a plurality of inserts is provided at a distance from one another around the centre of the cross-section in the outer region and/or in the centre of the cross-section. 10 The inserts preferably comprise fabrics or meshes, preferably manufactured from a metal. Apart from fabric and mesh, formed for example from wire, such inserts comprise also wefts, non-woven fabric or expanded metal. These inserts can be easily severed and furthermore can be simply positioned in the fastening element. For example, in addition to the magnetic elements distributed in the plastic material a wire mesh may be provided 15 externally as an insert on the fastening element. The plastic material is preferably fibre-reinforced, so that the fastening element is able to withstand tensile stresses that are greater than those for non-fibre-reinforced materials. The plastic material is advantageously reinforced using glass fibres. Such a 20 material is also designated as GFRP. Brief Description of the Drawings Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: 25 Fig.1 shows a lateral view of a fastening element in the employed state; Fig.2 shows a schematic illustration of the removal of separated pieces of the fastening element from the mined coal; 30 Fig.3 shows an enlarged cross-section through the fastening element shown in Fig.]; Fig.4 shows a cross-section of a second embodiment of a fastening element, analogously to Fig.3.
6 Preferred Embodiment of the Invention The same parts of the figures are typically designated throughout by the same reference numerals. 5 The rod-shaped fastening element 11, shown in Figs. I and 3, to be used in mining and tunnel construction, is manufactured from a fibre-reinforced plastic material 12, that comprises magnetic elements 13 and 14, distributed over the cross-section of the fastening element. The magnetic elements 13 are a powder from a magnetisable material, 10 such as for example, iron (Fe). The magnetic elements 14 are fibres or swarf from a magnetisable material, such as for example, cobalt (Co.). In this embodiment, in an outer edge region 16 of the of the circular cross-section, the magnetic elements 13 and 14 are in a greater concentration than in an inner region 17 15 of the cross-section, adjacent to the former one. In this embodiment, the cross-sectional dimension A of the outer edge region 16 with the increased concentration of the magnetic elements 13 and 14 corresponds to 15% of the outside diameter D as an applicable overall dimension of the cross-section. The concentration of the magnetic elements 13 and 14 in the outer edge region 16 of the cross-section, in this embodiment, is 2.5 times that of the 20 concentration of the magnetic elements 13 and 14 in the inner region 17 adjacent to it. In the centre of the cross-section of the fastening element 11 a central region 18 is provided that has a concentration of the magnetic elements 13 and 14 greater than that of the adjacent region 17 of the cross-section. The cross-sectional dimension C of the central 25 region 18 with the increased concentration of the magnetic elements 13 and 14 corresponds in this embodiment 25% of the outside diameter D as applicable overall dimension of the cross-section. The concentration of the magnetic elements 13 and 14 in the central region 18 of the cross-section is twice that of the concentration of the magnetic elements 13 and 14 in the region 17 adjacent to it. 30 Such a fastening element I1 is anchored to secure, for example, a lateral wall of a coal seam 6 in a prior produced bore 7 via a hardenable substance 8 and tightened by a tensioning nut 9 (see Fig.1). To mine the coal seam 6 a schematically illustrated coal plough is used as mining equipment 5, that on impact severs the fastening element 11.
7 The abraded coal 42, as well as the separated pieces 21 of the fastening element 11, are conveyed away by a conveyor belt 41 (see Fig.2). Due to the magnetic elements 13 and 14 with the suggested concentrations removal of almost all of the separated pieces 21 of the fastening element I I from the mined coal 41 is advantageously assured by means of a 5 magnet separator 43. The fastening element 31 illustrated in Fig.4, made from a plastic material 32, has a polygonal cross-section, that only in its outer edge region 36 has a concentration of magnetic elements 33 and 34 that is greater than that in the adjacent inner region 37 of the 10 cross-section. The cross-sectional dimension F of the outer edge region 36 in this embodiment corresponds in its thinnest position 10% of the applicable overall dimension E of the polygonal cross-section. The concentration of the magnetic elements 33 and 34 in the outer region 36 of the cross-section in this embodiment is 2.5 times that of the concentration of the magnetic elements 33 and 34 in the adjacent inner region 37 of the 15 cross-section. In the outer region 36 a further continuous wire mesh from a magnetic material is provided as an insert 35. 20 Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.