Hydraulic and earth engineering – Earth treatment or control – Shoring – bracing – or cave-in prevention
Patent
1997-03-20
1999-03-23
Graysay, Tamara L.
Hydraulic and earth engineering
Earth treatment or control
Shoring, bracing, or cave-in prevention
411 10, 411537, F16B 4300, F21D 2100
Patent
active
058850341
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a washer for use in mining and particularly but not exclusively for use with a load plate utilised in supporting a mine roof.
A known arrangement for supporting a roof of a mine is illustrated in FIG. 1 of the accompanying drawings. The arrangement 1 comprises a bolt 2 embedded in rock 3 and a load plate 4 secured against the rock face 10 by means of a tensioning nut 5 which is threadably fitted onto the bolt 2. Intermediate the nut 5 and the plate 4 is a domed element 6 which is mounted on the bolt so that a flat side 7 of the element faces the nut and curved surface 8 faces the plate 4. The element 6 provides a form of ball joint between the bolt 2 and the plate 4 by virtue of its hemispherical shape, to permit the plate 4 to be securely fastened to the rock face 10 even when the bolt 2 is angled away from the normal to the rock face 10.
The load plate 4 itself is formed of a base portion 11 and an upraised portion 12 which extends away from the general plane of the plate 4 and defines an opening 13 in which the element 6 is received.
One known form of the support member 4 is manufactured of steel and has dimensions in the order of 100.times.100.times.8 mm, with opening 13 in the order of 35 mm in diameter and upraised portion 12 extending in the order of 10 mm from the base portion 11. It has been found that such a support member is sufficient for the purpose of supporting loads in the order of 10 tonne but that loads in excess of 15 tonne cause the plate 4 to fail as a result of the projecting portion 12 deforming to such a degree that the element 6 and nut 5 pull through the support member 4, which in turn could lead to collapse of the ceiling 3.
It is an object of the present invention to provide a washer to improve the load bearing characteristics of the plate when used, for example, in an arrangement such as the arrangement 1 described above, and/or to provide some indication of when the load on the plate has reached a predetermined level prior to failure.
In accordance with the present invention there is provided a washer comprising a body portion defining a central opening and a tapered flange portion depending therefrom, the flange portion being tapered by a degree sufficient for the flange portion to deform outwardly upon application of a substantially axial predetermined compressive load.
Preferably, the flange portion is adapted to engage a load plate about an opening formed in the plate for receipt of a rockbolt, the outward deformation of the flange portion serving to increase the contact area between the washer and the plate to lower the contact stress therebetween.
Preferably, the outward deformation of the flange portion provides a visual indicator that the predetermined compressive load has been applied.
Preferably, the flange portion is adapted to fit over an upraised portion of a load plate which defines an opening for receipt of a rock bolt, and is configured to minimize contact between the upraised portion and the washer prior to application of the compressive load whereby to allow for ease of movement of the washer to accommodate for misalignment of the bolt and whereby the flange portion deforming during application of the compressive load results in an increased area of the flange portion being forced into contact with the load plate.
Preferably, the body portion has a recess formed in an end remote from the flange portion, the recess being adapted to receive a bearing assembly.
Alternatively the recess is configured so as to provide a seat for receipt of a domed element used for compensating for misalignment between a rockbolt and a load plate.
Preferably, the body portion of the washer includes a generally cylindrical internal surface and the flange portion has an internal surface which diverges outwardly from the cylindrical internal surface of the body portion.
The invention is more fully described, by way of non-limiting example only, with reference to the accompanying drawings in which:
FIG. 1 is a side view of a known arrangement for suppor
REFERENCES:
patent: 2850937 (1958-09-01), Ralston
patent: 3133468 (1964-05-01), Cumming
patent: 4431353 (1984-02-01), Capuano
patent: 4708559 (1987-11-01), Locotos
patent: 4889457 (1989-12-01), Hageman
patent: 5556234 (1996-09-01), Oldsen et al.
International Search Report in PCT/AU 95/00341, filing date 9 Jun. 1995, 4 pages in length.
Graysay Tamara L.
Industrial Rollformers Pty. Ltd.
Lagman Frederick L.
LandOfFree
Washer for use in mining does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Washer for use in mining, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Washer for use in mining will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2119653