CA2504058A1 - Mine roof support system having torque indicating washer - Google Patents
Mine roof support system having torque indicating washer Download PDFInfo
- Publication number
- CA2504058A1 CA2504058A1 CA 2504058 CA2504058A CA2504058A1 CA 2504058 A1 CA2504058 A1 CA 2504058A1 CA 2504058 CA2504058 CA 2504058 CA 2504058 A CA2504058 A CA 2504058A CA 2504058 A1 CA2504058 A1 CA 2504058A1
- Authority
- CA
- Canada
- Prior art keywords
- washer
- torque
- dome
- bore hole
- proximal end
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
- E21D21/0086—Bearing plates
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
- E21D21/02—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection having means for indicating tension
Abstract
A mine roof support system is provided which includes a conventional steel anchor rod or bolt, a threaded fastener and a torque indicating member. The anchor rod extends from a distal end portion to an externally threaded proximal end portion. The threaded fastener is a tensioning nut of a conventional design used in mine roof support applications, and is adapted to threadedly engage the proximal end of the anchor rod to tension the anchor rod once secured in a bore hole.
The torque indicating member includes one or more radially extending rods, pins, members or planar flanges which are selected to move or distort under a compressive force achieved by tightening the nut thereagainst with a first predetermined minimum torque selected less than the torque required to cause tear-out or failure of the anchor rod from the bore hole. The movement of the flanges thus provides a visual indication to an installer that a first torque force is being applied.
The torque indicating member includes one or more radially extending rods, pins, members or planar flanges which are selected to move or distort under a compressive force achieved by tightening the nut thereagainst with a first predetermined minimum torque selected less than the torque required to cause tear-out or failure of the anchor rod from the bore hole. The movement of the flanges thus provides a visual indication to an installer that a first torque force is being applied.
Description
MINE ROOF SUPPORT SYSTEM HAVING TORQUE INDICATING WASHER
SCOPE OF THE INVENTION
The present invention relates to a wall or mine roof support system, and more particularly a support system which includes an anchor or reinforcing rod or bolt having a threaded end, a nut or other threaded fastener for mated engagement with the threaded end of the bolt, and a torque indicating member, such as a washer, which provides an installer with a visual indication of the application of a first predetermined minimum torque on the nut. The torque indicating member enables the installer to better gauge torque forces on the nut and prevent over-tensioning of the rod in a mine roof or wall bore hole.
BACKGROUND OF THE INVENTION
In wall and mine roof support systems, the use of anchor rods or bolts under tension for ground control is well known. Typically, conventional support systems include a four or eight foot steel anchoring or reinforcing rod or bolt which is threaded at one end and a tensioning nut.
The anchor rod is embedded in a bore hole formed in the wall or mine roof to a depth selected such that when inserted, the threaded end of the rod projects outwardly a distance beyond the wall or rock face. To secure the anchor rod in the bore hole, the distal inner end of the rod may be provided with a wedge shaped mechanical anchoring member which is adapted to be drawn outwardly, wedging the distal end of the rod against the sides of the bore hole. Alternately, one or more adhesive resin cartridges are inserted into the bore hole ahead of the distal end of the rod. The subsequent insertion of the rod into the bore hole ruptures the cartridge to release the adhesive and secure the inner distal end of the anchor rod against removal from the bore hole.
Following the placement of the anchor rod in the bore hole, the nut is threaded along the projecting threaded proximal end portion of the rod, and tightened axially against the wall or rock face, to consolidate forces within the rock and control ground movement.
SCOPE OF THE INVENTION
The present invention relates to a wall or mine roof support system, and more particularly a support system which includes an anchor or reinforcing rod or bolt having a threaded end, a nut or other threaded fastener for mated engagement with the threaded end of the bolt, and a torque indicating member, such as a washer, which provides an installer with a visual indication of the application of a first predetermined minimum torque on the nut. The torque indicating member enables the installer to better gauge torque forces on the nut and prevent over-tensioning of the rod in a mine roof or wall bore hole.
BACKGROUND OF THE INVENTION
In wall and mine roof support systems, the use of anchor rods or bolts under tension for ground control is well known. Typically, conventional support systems include a four or eight foot steel anchoring or reinforcing rod or bolt which is threaded at one end and a tensioning nut.
The anchor rod is embedded in a bore hole formed in the wall or mine roof to a depth selected such that when inserted, the threaded end of the rod projects outwardly a distance beyond the wall or rock face. To secure the anchor rod in the bore hole, the distal inner end of the rod may be provided with a wedge shaped mechanical anchoring member which is adapted to be drawn outwardly, wedging the distal end of the rod against the sides of the bore hole. Alternately, one or more adhesive resin cartridges are inserted into the bore hole ahead of the distal end of the rod. The subsequent insertion of the rod into the bore hole ruptures the cartridge to release the adhesive and secure the inner distal end of the anchor rod against removal from the bore hole.
Following the placement of the anchor rod in the bore hole, the nut is threaded along the projecting threaded proximal end portion of the rod, and tightened axially against the wall or rock face, to consolidate forces within the rock and control ground movement.
To achieve the desired placement of mechanical wedge anchors and/or initial mixing of the resin, the threaded nuts used to tension the rod may be provided with either a deformable end or a releasable end cap, as for example is disclosed in United States Patent No. 5,873,689 to Mensour et al which issued February 23, 1999. Mensour et al discloses the use of a dome nut having a covered end which is adapted to release upon the application of relatively lower torque forces, such as those below 100 ft.lbs. The domed or covered end of the nut initially prevents its movement axially along the threaded end of the rod. This results in the rod spinning about its axial length with the nut to either achieve mechanical placement of the wedge anchor or mixing of the adhesive resin, prior to the securement of the distal end relative to the bore hole.
Following securement of the rod by wedge anchor placement or setting up of the resin, the nut is torqued with sufficient force to release or distort the end cap, allowing the nut to be threaded along the rod and tightened against the rock face.
Heretofore, the applicant has appreciated a disadvantage with prior art wall and mine roof support systems and their methods of installation. Following the release of the nut end cap and the running of the nut along the threaded proximal end against the rock face, the inadvertent over-torquing of the nut against the wall or rock face may result in the anchor rod tearing Ollt of the set resin or, in the case where mechanical wedge fasteners are used, failing outright. If this occurs, the installed bolt will be of no effective use in consolidating rock forces. In particular, prior art rock support systems suffer the disadvantage in that in the initial tensioning of the nut to compress the rock complex, as the nut is tightened, the installer is unaware as to precisely when the nut and/or any intervening washer plates and/or mesh screening seats against the exposed rock face as tensioning torque is applied. As a result, where a power drive is used to install the nut, it is liable to be overtorqued prior to the installer realizing that the nut has been fully seated against the rock face.
SUMMARY OF THE INVENTION
Accordingly, an object of the invention is to provide a torque indicating member or washer which includes a dome-shaped portion and one or more radial flanges.
The flanges are adapted to deflect from a first position to a second position upon the compression of the dome-shaped portion, as for example which occurs by tightening a nut against the torque indicating member with a predetermined first minimum torque.
Another object of the invention is to provide a torque indicating member or washer which has a bent generally dome-shaped portion which extends in an axial direction, and which upon the application of a second compressive force achieved by tightening a nut against the washer with a torque selected greater than a first predetermined minimum torque, substantially collapses in the direction of applied compressive force.
A further object of the invention is to provide a method of installing a wall or mine roof support system which includes a reinforcing rod, a threaded fastener and a torque indicating member or washer which is adapted to provide an installer with a visual indication of the application of a first predetermined minimum torque on the threaded fastener, and wherein part or all of the torque indicating member has applied thereto a high visibility coating or colour selected to provide enhanced visibility in low light conditions experienced in underground mice operations.
Another object of the invention is to provide a concrete wall or mine roof support system, (hereinafter also generally referred to as mine roof support systems), which includes an anchor rod sized for insertion in a bore hole formed into a wall, a threaded tensioning nut and a torque indicating washer which is provided as either a stand alone component or as part of the anchor nut, and which provides a visual indication of the application of a compressive force achieved by tightening the nut with a first predetermined minimum torque selected less than a torque necessary to achieve tear-out of the anchor rod from the bore hole.
To overcome at least some of the disadvantages associated with prior art support systems and methods, a mine roof support system is provided which includes a conventional steel anchor rod or bolt, a threaded fastener and a torque indicating member. The anchor rod is elongated along a longitudinal axis, extending from a distal end portion to an externally threaded proximal end portion. The threaded fastener is preferably a steel or iron tensioning nut of a conventional design used in mine roof support applications, and is adapted to threadedly engage the proximal end of the anchor rod to tension the anchor rod once secured in a bore hole.
The torque indicating member is adapted to be positioned between the rock face and the tensioning nut so that the tightening of the nut along the threaded end of the rod exerts a compressive force thereon.
The torque indicating member may be provided either as a separate element or as part of the tensioning nut and is adapted to provide a visual indication to an installer of a selected compressive force being applied thereto by the threaded fastener. Preferably, the torque indicating member includes one or more radially extending rods, pins, members or generally flanges which may be planar, bent or curved (the foregoing hereinafter generally indicated as flange portions) and which are selected to move, deflect or otherwise distort under a compressive force achieved by tightening the nut with a first predetermined minimum torque. The first predetermined minimum torque is preferably selected less than the torque required to cause tear-out or failure of the anchor rod from the bore hole. The movement of the flanges thus provides a visual indication to an installer that a first torque force is being applied on the tightening nut.
In one other aspect, the present invention provides a torque indicating member which is adapted for positioning between a rock face and a tensioning nut used in mine roof support systems, to provide a rock bolt installer with a visual indication of the application of certain torque forces on the threaded fastener when tensioning a rock bolt. The torque indicating member includes a bent portion which is configured to extend, in use, in a generally axial elongated direction of an installed anchor bolt or rod. More preferably, the torque indicating member includes an opening therethrough which is sized to permit placement of the member over a projecting threaded end of an anchor rod which has been positioned in a bore hole as a washer. In a simplified construction, planar tabs or flanges extend radially from the bent portion of the washer and are adapted to deflect, deform or distort following the application of a first compressive force on the torque indicating member achieved by tightening the tensioning nut thereagainst with a first predetermined minimum torque.
In a preferred construction, the torque indicating member is formed as a dome washer having a bent and more preferably generally dome-shaped portion which curves in an axial direction, and one or more flange portions which extend radially from a peripheral edge of the dome-shaped portion. An opening is provided through the axial center of the dome-shaped portion to enable the washer to be slid over the threaded proximal end portion of an anchor rod.
ahead of the tensioning nut, with the dome-shaped portion curving from its peripheral edge outwardly away from the rock face. Once the rod has been secured in place with its distal end in a bore hole, tightening of the nut results in the application of an axially compressive force against the dome-shaped portion and initial radially outward deflection of the peripheral edge.
The initial outward deflection of the peripheral edge results in radial outward forces being applied to the flanges where they join with the dome-shaped portion. The outward forces in turn result in the twist deformation andlor bending of the flange members, providing the installer with the visual indication that the nut is being tightened with the first predetermined torque.
Although not essential, most preferably the dome-shaped portion curves with a radial diameter selected at between about 1 cm and 8 cm, and a radius of curvature selected at between about .3 and 1.5 cm. Preferably, the flange portions are joined along portions of the peripheral edge of the dome-shape portion, such that the application of the compressive force on the dome-shape portion achieved by tightening the nut with the first predetermined minimum torque is selected less than compressive force necessary to substantially collapse and/or compress the dome-shaped portion, while producing the radial outward deflection of the peripheral edge. In this manner, the radial outward deflection of the peripheral edge, in turn, produces strain along the flange portion/peripheral edge interface, to elastically deform at least part of the flange portions so as to move axially.
In a most simplified construction, the torque indicating washer is formed as a dome washer which is stamped from a single, generally planar sheet of 8 to 20 gauge metal, such as steel, however, other metal thicknesses and/or types may also be used.
Accordingly, in another aspect the present invention resides in a method of installing a mine roof support system in a bore hole formed in a rock face, the support system comprising, an elongated anchor member extending axially from a distal end portion to a threaded proximal end portion, a generally semi-spherical member for placement generally proximate to said rock face, the semi-spherical member having an opening therethrough sized to permit sliding placement of said member over said proximal end portion, and including a generally hemispherical surface portion and a generally planar surface portion, a torque indicating washer having a radially extending peripheral portion and a generally dome-shaped portion which curves convexly forward relative to said peripheral portion and which further comprises a generally centrally positioned aperture sized for enabling placement of said torque indicating washer over said proximal end portion, a threaded fastener sized for threaded coupling with the proximal end portion of the anchor member, the mine support system installed by, inserting the distal end of the anchor member into the rock wall bore hole so that the proximal end projects at least partially outwardly therefrom past said rock face, with the semi-spherical member positioned over the distal end portion such that the hemispherical surface portion faces inwardly and the torque indicating washer positioned over the proximal end portion spaced outwardly from the semi-spherical member and oriented with the dome-shaped portion curving convexly outwardly, rotating the threaded fastener along the proximal portion relative to said anchor rod to move the fastener axially towards initial engagement with the torque indicating washer, applying a first predetermined minimum torque on said threaded fastener to impart a compressive force by said fastener against said torque indicating washer and produce an initial deflection of said peripheral portion to provide a visual indication of said fiirst minimum torque, and applying a second minimum torque on said threaded fastener to compress and at least partially deform said dome-shaped portion towards contact with said planar surface portion of said semi-spherical member.
In yet another aspect, the present invention resides in a method of installing a support system in a bore hole formed in a rock or wall face, the support system comprising, an anchor rod being elongated along an axis from a distal end portion to an externally threaded proximal end portion, a seating member for placement generally proximate to said rock or wall face, the seating member having an opening therethrough sized to permit sliding placement of said seating member over said proximal end portion, a torque indicating washer having a radially extending peripheral portion and a dome-shaped portion which curves convexly forward relative to said peripheral portion and further comprising an aperture therethrough sized for enabling sliding placement of said torque indicating washer over said proximal end portion, a threaded fastener sized for threaded coupling with the proximal end portion of the anchor rod, whereby rotation of said fastener relative to said anchor rod moves the fastener axially along the proximal end portion, the support system being installed by, inserting the distal end of the anchor member into the bore hole so that the proximal end projects at least partially outwardly therefrom past said rock or wall face, with the seating member and torque indicating member positioned over the distal end portion such that the torque indicating member is spaced outwardly ti-om the seating member and in an orientation with the dome-shaped portion curving convexly outwardly, rotating the threaded fastener along the proximal portion relative to said anchor rod to move the fastener axially into engaging contact with the torque indicating washer, wherein the application of a first predetermined minimum torque on said threaded fastener against said torque indicating washer produces an initial outward deflection of said peripheral portion to provide a visual indication of said first minimum torque, and the application of a second minimum torque on said threaded fastener compresses and at least partially deforms said dome-shaped portion towards juxtaposed contact with said seating member.
In a further aspect, the present invention resides in a torque indicating dome washer for use in a mine or wall support system the washer comprising a generally dome-shaped portion extending generally axially forward from a peripheral edge, said dome-shaped member having a radius of curvature selected such that the application of a selected compressive force axially thereon produces partial radial deflection of said peripheral edge, and at least one flange portion extending radially outwardly from said peripheral edge of said dome-shaped portion, wherein the partial radial deflection of said peripheral edge produces a compressive strain on said flange portion to distort or deform said flange portion.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference may now be had to the following detailed description taken together with the accompanying drawings in which:
Figure 1 illustrates schematically a conventional mine roof support system in an installed configuration in a rock complex;
Figure 2 illustrates a schematic perspective plan view of a torque indicating dome washer in accordance with a preferred embodiment of the invention;
Figure 3 illustrates a cross-sectional view of the dome washer shown in Figure 2 taken along line 3-3';
Figure 4 illustrates an enlarged schematic plan view of the torque indicating dome washer of Figure 2;
Figure 5 illustrates an exploded view showing the installation of the dome washer of Figure 2 as part of a mine roof support system used in the support of a rock complex;
Figure 6 illustrates a cross-sectional side view of the torque indicating dome washer of Figure 2 in an initial installed position next to a spherical seat used in the support system of Figure 5;
Figure 7 illustrates a schematic cross-sectional view of the torque indicating dome washer of Figure 6 following the application of a compressive load by rotating the threaded nut of the mine roof support system of Figure 5 thereagainst with a first predetermined minimum torque;
Figures 8 to 11 show a series of schematic and cross-sectional views of a rock structure, illustrating the installation of the mine roof support and reinforcement system of Figure ~ in accordance with the present invention;
Figure 12 illustrates a schematic perspective view of a threaded nut having a torque indicating washer integrally joined thereto, in accordance with an alternate embodiment of the invention; and Figure 13 illustrates schematically a perspective plan view of a torque indicating washer in accordance with a further embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference is first made to Figure 1 which illustrates a prior art mine roof support system used to consolidate ground movement in a rock complex 8. The support system 10 includes a threaded cast or capped steel dome nut 12 and a steel anchor rod 14. The anchor rod 14 is elongated along its longitudinal axial length, and extends from a threaded outer proximal end portion 16 to an inner distal end portion 18. In the embodiment shown, the distal portion 18 is secured in place in a bore hole 20 formed in the rock complex 8 by a set adhesive resin 22.
In installation, the bore hole 20 is drilled into the rock complex 8 to a desired diameter and depth. A number of two-part resin cartridges (shown as reference numerals 24a,24b in Figure 8) are then inserted into the bore hole 20 ahead of the distal end portion 18 of the steel rod 14. The distal end portion 18 of the rod is next inserted into the bore hole 20 to pierce the cartridges 24a,24b and mix the resin. Optionally, secondary reinforcing components, such as a steel reinforcing plate 26 and/or mesh screen, may be positioned over the projecting proximal end 16 of the rod 14. The nut 12 is then threaded onto the proximal end 16 and tightened against the plate 26 and outer face 30 of the rock complex 8. The tensioning of the nut 12 against the plate 26 compresses the rock complex 8 to provide the desired degree of ground control. If;
however, as a result of inadvertence, the installer over-torques the nut 12, this may result in the tearing out of the rod 14 from the anchoring resin 22, resulting in rod failure, and necessitating the installation of a second anchor rod in an adjacent location.
Figures 2 and 3 illustrate a torque indicating washer 36 for use with the nut I 2, rod 14 and reinforcing plate 26 of the mine roof support system 10 of Figure l, and which is adapted to minimize the likelihood of anchor rod 14 tear out. As will be described, the washer 36 is adapted to be used in conjunction, not only with an anchor rod 14, threaded nut 12 and anchor plate 26, but optionally also a cast steel semi-spherical seat 70 (Figure 5) in the tensioning and ground control of the rock complex 8.
The washer 36 includes a central generally dome-shaped portion 38 which curves forwardly from a peripheral radial edge 40 in a forward direction along axis Ai-A, (Figure 3).
An opening 42 is formed through the axial apex of the dome-shaped portion 38.
The opening 42 is sized marginally greater than the diameter of the rod 14 to enable the washer 36 to be slid over the projecting threaded proximal end 16 of the anchor rod 14 following its placement in a bore hole 20. The dome-shaped portion 46 has a preferred radial diameter d~ of between about 2 and 4 cm, and a radius of curvature of approximately .6 to 1.2.
In the embodiment shown, the dome-shaped portion 46 is stamped from a generally square sheet of 12 gauge steel. The overall size of the sheet is selected such that following its formation, the dome-shaped portion 38 extends substantially to the mid-lateral edges 44 of the washer 36, so as to substantially define four radially projecting generally triangular flange portions 52a,52b,52c,52d integrally formed therewith. Each of the flange portions 52 is formed as a generally planar metal tab or flange which, prior to deformation of the washer 36, are substantially coplanar to each other. Each flange portion 52a,52b,52c,52d further merges along a respective radial quadrant A,B,C,D (Figure 4) with the peripheral edge 40 of the dome-shaped portion 38, and projects outwardly to a radial distance dt outwardly therefrom of between about .7 and 3 cm.
The dome-shaped portion 38 of the torque indicating washer 36 is formed so that the application of a compressive force in the axial direction on the dome-shaped portion 38 results in the initial partial radial outward deflection of the peripheral edge 40, as for example in the direction of arrows 60 (Figure 4). Most preferably, the deflection of the peripheral edge 40 occurs radially about the axis A-A~, and where the compressive force required for deflection is selected as the force directly or indirectly on the washer 36 achieved by tightening the nut 12 along the threaded portion 16 of the rod with a first treated predetermined minimum torque. The first predetermined torque is selected less than the torque necessary to completely deform and flatten the dome-shaped portion 38 and/or result in tear out of the anchor rod 14 from set anchoring resin 22.
In the preferred mine roof assembly 10 shown in Figure S, the dome washer 10 is used in conjunction with a semi-spherical seat 70 which is adapted to translate any tensioning forces at the rock face 30/bore hole 20 interface in a direction generally parallel to the rod axis. The semi-spherical seat 70 is formed as a cast steel member having a planar forward side surface 72, and a generally hemispherical rearward surface 74. A bore hole 76 having a diameter greater than the diameter of the threaded proximal end 16 of the anchor rod 14 extends perpendicularly from the planar surface 74 and through the apex of the hemispherical surface 74. As will be described, the bore hole 76 allows the seat 70 to be slid over the projecting threaded proximal end 16 of the rod 14.
Preferably, the diameter d~ of the dome-shape portion 38 is selected less than the maximum radial diameter ds (Figure 5) of the planar surface 72 of the semi-spherical seat 70, allowing the peripheral surface 40 to be fully supported by the seat 70.
Although not essential, the dome-shaped washer 36 preferably has a maximum width w (Figure 3) from the tip of flange 52a to the tip of the radially opposite flange 52b of about 2 and 6 cm, and which is selected marginally greater than the minimum radial diameter of the threaded nut 12, and more preferably greater than the maximum diameter of the nut 12. As will be described, with this configuration, in installation of the mine roof support system 10 the flange portions 52a,52b,52c,52d project radially outward beyond the nut 12 so as to remain visible during the tightening of the nut 12 along the threaded end 16.
Figures 6 and 7 illustrate best the use of the torque indicating washer 38 as providing the installer with a visual indication when a predetermined minimum torque is first applied on nut 12 in the tensioning of the anchor rod 14. As the nut 12 compresses the washer 36 and is turned with a torque equal to the first predetermined torque, the peripheral edge 40 deforms outwardly.
As the peripheral edge 40 moves radially outward in the direction of arrows 60, the outward deflection of the dome-shaped portion 38 at radially offset locations relative to each of the flanges 52,52b,52c,52d results in the planar flanges distorting and curling forwardly in the direction of arrows 62 (Figure 7). Because of their lateral extent beyond the diameter of the nut 12, the deflection of the flanges 52a,52d is visible readily to the installer.
This deflection enables the installer to determine that the washer plate 26 and spherical seat 70 have been fully seated against the rock face 30 and that the first torque force is being applied on the tightened nut 12.
The visual indication of torque forces on the nut 12 provide the installer with an opportunity to more gradually tighten the nut 12 downwardly against the rock complex 8, minimizing the likelihood that the nut 12 may be over-torqued.
Following the application of the first predetermined minimum torque, the nut 12 is preferably rotated at a second greater torque force to apply a higher compressive axial force on the torque indicating washer 36. The second torque force is preferably sufficient to at least partially and more preferably substantially collapse the dome-shaped portion 38 against the planar surface 72 of the spherical seat 70, as for example is shown in phantom, but which is selected less than the torque force necessary to achieve tear out of the anchor rod 14 from the set resin 22 (Figure 1).
Figures 6 to 11 illustrate best the installation of the mine roof/wall anchoring system 10 utilizing the torque indicating washer 38 of Figure 2. As shown best in Figures 6 and 7, a bore hole 20 is conventionally drilled in the rock complex 8 generally perpendicular to the rock force 30 and to a depth of about 8 feet. A number of resin cartridges 24a,24b are next inserted into the bore hole 20. A conventional steel reinforcing rod 14 having an overall axial length selected approximately two to six inches longer than the bore hole 20 and an externally threaded proximal end portion 14 which extends two to six inches from the proximal endmost tip 66 is next inserted into the bore hole 20. The distal end portion 18 of the rod 14 is slid into the bore hole 20 to rupture the cartridges 24a,24b, releasing the resin therefrom.
The washer plate 26 and semi-spherical seat 70 are then positioned over the portion of the proximal end 16 which extends past the rock face 30. The semi-spherical seat 70 is positioned so that the hemispherical surface 74 of the seat 70 is oriented towards the rock complex 8 and in juxtaposed contact with the plate washer 26. As will be described, with this positioning, the tightening of the nut 12 along the threaded proximal portion 16 results in tensioning forces being substantially maintained axially along the length of the anchor rod 14.
Following the positioning of the reinforcing plate 26 and semi-spherical seat 70, the torque indicating washer 36 is next positioned over threaded proximal end 14.
The washer 36 is slid against the semi-spherical seat 70 so that the dome-shaped portion 38 curves forwardly.
outwardly from the bore hole 20, and with the flanges 52 and peripheral edge surface 40 moved against the planar surface 72.
Next, a capped dome nut 12 which has a releasable cap member 110 secured thereto is threaded onto the end tip 66 of the rod 14, as for example is shown in Figure 10. While the resin remains unset, the dome nut 12 is rotated about the rod axis by means of a power winch, thereby turning the rod 14 about its axial length to mix the released resin. Once the resin has set securing the distal end 18 of the rod 14 in the bore hole 20, the nut 12 is rotated at a high torque force of about 50 to 75 ft.lbs. or less. The higher torque forces on the nut 12 relative to the secured rod 14 results in its deformation and the detachment of the cap member 110 enabling the nut 12 to be run axially along the rod 14 towards the rock face 30.
The tightening of the nut 12 initially slides the plate 26, spherical seat 70 and torque indicating washer 36 to a first position snugly pushed against the rock face 30. As the installer continues to rotate the nut 12 relative to the anchor rod 14, the tightening of the nut 12 provides an axial compressive force on the dome-shaped portion 38 of the washer 36 in the direction of arrows 100 (Figure 7). Once the compressive force equals that applied by the first predetermined minimum torque force on the nut 12, and which most preferably is selected at between about 80 and 125 ft.lbs., the compression of the dome-shaped portion 38 produces a slight outward deflection of the peripheral edge 40. The radial deflection of the edge 40 produces compressive strain at the peripheral edge 40/flange 52 junction as the peripheral edge 40 moves marginally radially outward. The radial outward movement of the peripheral edge 40 thus results in the flange portions 52a,52b,52c,52d deforming forwardly providing the visual indication of the first torque to the installer. Thereafter the installer adjusts the torque forces on the nut 12, and tightens the nut with the second torque force, such that the dome-shaped portion 38 substantially collapses to the flattened position in juxtaposed contact with the planar surface 72 of the spherical seat 70 as is shown in Figure 11.
Although not shown, optionally following the tightening of the nut 12 to the fully seated position of Figure 11, push plates or mesh screening may be affixed to the remaining projecting proximal end 16 of the rod 14 which extends outwardly therefrom in a conventional manner.
Although Figures 2 to 5 illustrate the torque indicating dome washer as comprising a separate component adapted for placement interposed between the semi-spherical seat 70 and nut 12, the invention is not so limited. Figure 12 illustrates an alternate embodiment where like reference numerals are used to identify like components. In Figure 12, a washer nut 120 is provided with a torque indicating washer 32 joined thereto as an integral unit. In Figure 12, the torque indicating washer 38 has essentially the identical construction as that shown in Figure 2.
The washer 32 is spot welded directly to the inner end face 122 of a capped dome nut 12 as a single unit. The torque indicating washer 38 is joined to the dome nut end face 122 with the opening 42 co-axially aligned with a releasable end cap 110 and the threaded interior of the nut 12. Preferably, the dome-shaped portion 38 of the washer 36 is joined to the nut 12 only about the immediate periphery of the opening 42. This construction advantageously ensures that the coupling of the washer 36 to the nut 12 does not adversely affect the outward deflection of the peripheral edge 40, or the compression of the dome-shaped portion 38 upon the application of axial forces. It is to be appreciated that the washer nut 120 of Figure 12, in addition to providing a more compact design, avoids the requirement to separately position the torque indicating washer 36 on the rod 14 ahead of the nut 12.
Although the preferred embodiment of the invention describes the positioning of the plate anchor 26, semi-spherical seat 70, torque indicating washer 36 and tensioning nut 12 following the placement of the anchor rod 14 in the bore hole 20, the invention is not so limited. Tt is to be appreciated that in an alternate construction, the washer plate 26, semi-spherical seat 70, torque indicating dome washer 36 and nut 12 could be prepositioned over the threaded proximal end 16 of the anchor rod 14, prior to the insertion of the distal end 18 in the bore hole 20 and the rupture of the resin cartridges 24a,24b thereby.
Although the preferred embodiment of the invention describes and illustrates the torque indicating washer 36 as having four planar flanges 52a,52b,52c,52d which are integrated with the peripheral edge 40, the invention is not so limited. It is to be appreciated that other flange configurations which are adapted to deform or deflect under a predetermined compressive force are also possible and will now become readily apparent. In addition, the torque indicating washer 36 could be provided with fewer or larger number of different shaped flanges which are adapted to distort under a predetermined axial load without departing from the spirit and scope of the invention. Reference may be had to Figure 13 which illustrates one alternate possible embodiment of the invention wherein like reference numerals are used to identify like components. In Figure 13, the torque indicating washer 36 is provided with only two flanges 52a,52b at radially opposite locations. As with the embodiment described with reference to Figures 2 and 3, the application of an axial compressive force on the dome-shaped portion 38 of the washer 36 results in the deflection of the flanges 52a,52b, to provide the installer with the visual indication that a tensioning nut has been tightened with the first predetermined minimum torque.
Although not essential, more preferably at least the flanges 52a,52b, and in a simplified construction the entire forward surface of the dome washer 36 has a high visibility coating 90 applied thereto. By way of non-limiting example, the high visibility coating 90 could comprise a fluorescent paint selected to provide enhanced visibility of the washer 36 in low light conditions which, for example, would be typically experienced in underground mining operations.
Although the preferred embodiment of the invention describes the securement of the anchor rod 14 in the rock complex bore hole 20 by the use of mixed resin 22, the invention is not so limited. It is to be appreciated that the present invention is equally suited for use with anchor rods which are held in place by means of mechanical anchors including, without restriction, the use of wedge bolts and the like.
Although the detailed description describes the support system 10 as including an anchor rod 14, tensioning nut 12, semi-spherical seat 70, plate anchor 26 and dome washer 36, the invention is not restricted to the specific components. It is to be appreciated that the support system 10 could be provided with fewer or additional components used in concrete wall reinforcement and/or mine roof reinforcement. These components could include without restriction mesh screening, push plates or other components used in conventional support systems provided in place of or in addition to the spherical seat 70 and/or washer plate 26 illustrated in Figure 4.
Although the detailed description describes and illustrates various preferred embodiments, the invention is not so limited. Many modifications and variations will now occur to persons skilled in the art. For a definition of the invention, reference may be had to the appended claims.
Following securement of the rod by wedge anchor placement or setting up of the resin, the nut is torqued with sufficient force to release or distort the end cap, allowing the nut to be threaded along the rod and tightened against the rock face.
Heretofore, the applicant has appreciated a disadvantage with prior art wall and mine roof support systems and their methods of installation. Following the release of the nut end cap and the running of the nut along the threaded proximal end against the rock face, the inadvertent over-torquing of the nut against the wall or rock face may result in the anchor rod tearing Ollt of the set resin or, in the case where mechanical wedge fasteners are used, failing outright. If this occurs, the installed bolt will be of no effective use in consolidating rock forces. In particular, prior art rock support systems suffer the disadvantage in that in the initial tensioning of the nut to compress the rock complex, as the nut is tightened, the installer is unaware as to precisely when the nut and/or any intervening washer plates and/or mesh screening seats against the exposed rock face as tensioning torque is applied. As a result, where a power drive is used to install the nut, it is liable to be overtorqued prior to the installer realizing that the nut has been fully seated against the rock face.
SUMMARY OF THE INVENTION
Accordingly, an object of the invention is to provide a torque indicating member or washer which includes a dome-shaped portion and one or more radial flanges.
The flanges are adapted to deflect from a first position to a second position upon the compression of the dome-shaped portion, as for example which occurs by tightening a nut against the torque indicating member with a predetermined first minimum torque.
Another object of the invention is to provide a torque indicating member or washer which has a bent generally dome-shaped portion which extends in an axial direction, and which upon the application of a second compressive force achieved by tightening a nut against the washer with a torque selected greater than a first predetermined minimum torque, substantially collapses in the direction of applied compressive force.
A further object of the invention is to provide a method of installing a wall or mine roof support system which includes a reinforcing rod, a threaded fastener and a torque indicating member or washer which is adapted to provide an installer with a visual indication of the application of a first predetermined minimum torque on the threaded fastener, and wherein part or all of the torque indicating member has applied thereto a high visibility coating or colour selected to provide enhanced visibility in low light conditions experienced in underground mice operations.
Another object of the invention is to provide a concrete wall or mine roof support system, (hereinafter also generally referred to as mine roof support systems), which includes an anchor rod sized for insertion in a bore hole formed into a wall, a threaded tensioning nut and a torque indicating washer which is provided as either a stand alone component or as part of the anchor nut, and which provides a visual indication of the application of a compressive force achieved by tightening the nut with a first predetermined minimum torque selected less than a torque necessary to achieve tear-out of the anchor rod from the bore hole.
To overcome at least some of the disadvantages associated with prior art support systems and methods, a mine roof support system is provided which includes a conventional steel anchor rod or bolt, a threaded fastener and a torque indicating member. The anchor rod is elongated along a longitudinal axis, extending from a distal end portion to an externally threaded proximal end portion. The threaded fastener is preferably a steel or iron tensioning nut of a conventional design used in mine roof support applications, and is adapted to threadedly engage the proximal end of the anchor rod to tension the anchor rod once secured in a bore hole.
The torque indicating member is adapted to be positioned between the rock face and the tensioning nut so that the tightening of the nut along the threaded end of the rod exerts a compressive force thereon.
The torque indicating member may be provided either as a separate element or as part of the tensioning nut and is adapted to provide a visual indication to an installer of a selected compressive force being applied thereto by the threaded fastener. Preferably, the torque indicating member includes one or more radially extending rods, pins, members or generally flanges which may be planar, bent or curved (the foregoing hereinafter generally indicated as flange portions) and which are selected to move, deflect or otherwise distort under a compressive force achieved by tightening the nut with a first predetermined minimum torque. The first predetermined minimum torque is preferably selected less than the torque required to cause tear-out or failure of the anchor rod from the bore hole. The movement of the flanges thus provides a visual indication to an installer that a first torque force is being applied on the tightening nut.
In one other aspect, the present invention provides a torque indicating member which is adapted for positioning between a rock face and a tensioning nut used in mine roof support systems, to provide a rock bolt installer with a visual indication of the application of certain torque forces on the threaded fastener when tensioning a rock bolt. The torque indicating member includes a bent portion which is configured to extend, in use, in a generally axial elongated direction of an installed anchor bolt or rod. More preferably, the torque indicating member includes an opening therethrough which is sized to permit placement of the member over a projecting threaded end of an anchor rod which has been positioned in a bore hole as a washer. In a simplified construction, planar tabs or flanges extend radially from the bent portion of the washer and are adapted to deflect, deform or distort following the application of a first compressive force on the torque indicating member achieved by tightening the tensioning nut thereagainst with a first predetermined minimum torque.
In a preferred construction, the torque indicating member is formed as a dome washer having a bent and more preferably generally dome-shaped portion which curves in an axial direction, and one or more flange portions which extend radially from a peripheral edge of the dome-shaped portion. An opening is provided through the axial center of the dome-shaped portion to enable the washer to be slid over the threaded proximal end portion of an anchor rod.
ahead of the tensioning nut, with the dome-shaped portion curving from its peripheral edge outwardly away from the rock face. Once the rod has been secured in place with its distal end in a bore hole, tightening of the nut results in the application of an axially compressive force against the dome-shaped portion and initial radially outward deflection of the peripheral edge.
The initial outward deflection of the peripheral edge results in radial outward forces being applied to the flanges where they join with the dome-shaped portion. The outward forces in turn result in the twist deformation andlor bending of the flange members, providing the installer with the visual indication that the nut is being tightened with the first predetermined torque.
Although not essential, most preferably the dome-shaped portion curves with a radial diameter selected at between about 1 cm and 8 cm, and a radius of curvature selected at between about .3 and 1.5 cm. Preferably, the flange portions are joined along portions of the peripheral edge of the dome-shape portion, such that the application of the compressive force on the dome-shape portion achieved by tightening the nut with the first predetermined minimum torque is selected less than compressive force necessary to substantially collapse and/or compress the dome-shaped portion, while producing the radial outward deflection of the peripheral edge. In this manner, the radial outward deflection of the peripheral edge, in turn, produces strain along the flange portion/peripheral edge interface, to elastically deform at least part of the flange portions so as to move axially.
In a most simplified construction, the torque indicating washer is formed as a dome washer which is stamped from a single, generally planar sheet of 8 to 20 gauge metal, such as steel, however, other metal thicknesses and/or types may also be used.
Accordingly, in another aspect the present invention resides in a method of installing a mine roof support system in a bore hole formed in a rock face, the support system comprising, an elongated anchor member extending axially from a distal end portion to a threaded proximal end portion, a generally semi-spherical member for placement generally proximate to said rock face, the semi-spherical member having an opening therethrough sized to permit sliding placement of said member over said proximal end portion, and including a generally hemispherical surface portion and a generally planar surface portion, a torque indicating washer having a radially extending peripheral portion and a generally dome-shaped portion which curves convexly forward relative to said peripheral portion and which further comprises a generally centrally positioned aperture sized for enabling placement of said torque indicating washer over said proximal end portion, a threaded fastener sized for threaded coupling with the proximal end portion of the anchor member, the mine support system installed by, inserting the distal end of the anchor member into the rock wall bore hole so that the proximal end projects at least partially outwardly therefrom past said rock face, with the semi-spherical member positioned over the distal end portion such that the hemispherical surface portion faces inwardly and the torque indicating washer positioned over the proximal end portion spaced outwardly from the semi-spherical member and oriented with the dome-shaped portion curving convexly outwardly, rotating the threaded fastener along the proximal portion relative to said anchor rod to move the fastener axially towards initial engagement with the torque indicating washer, applying a first predetermined minimum torque on said threaded fastener to impart a compressive force by said fastener against said torque indicating washer and produce an initial deflection of said peripheral portion to provide a visual indication of said fiirst minimum torque, and applying a second minimum torque on said threaded fastener to compress and at least partially deform said dome-shaped portion towards contact with said planar surface portion of said semi-spherical member.
In yet another aspect, the present invention resides in a method of installing a support system in a bore hole formed in a rock or wall face, the support system comprising, an anchor rod being elongated along an axis from a distal end portion to an externally threaded proximal end portion, a seating member for placement generally proximate to said rock or wall face, the seating member having an opening therethrough sized to permit sliding placement of said seating member over said proximal end portion, a torque indicating washer having a radially extending peripheral portion and a dome-shaped portion which curves convexly forward relative to said peripheral portion and further comprising an aperture therethrough sized for enabling sliding placement of said torque indicating washer over said proximal end portion, a threaded fastener sized for threaded coupling with the proximal end portion of the anchor rod, whereby rotation of said fastener relative to said anchor rod moves the fastener axially along the proximal end portion, the support system being installed by, inserting the distal end of the anchor member into the bore hole so that the proximal end projects at least partially outwardly therefrom past said rock or wall face, with the seating member and torque indicating member positioned over the distal end portion such that the torque indicating member is spaced outwardly ti-om the seating member and in an orientation with the dome-shaped portion curving convexly outwardly, rotating the threaded fastener along the proximal portion relative to said anchor rod to move the fastener axially into engaging contact with the torque indicating washer, wherein the application of a first predetermined minimum torque on said threaded fastener against said torque indicating washer produces an initial outward deflection of said peripheral portion to provide a visual indication of said first minimum torque, and the application of a second minimum torque on said threaded fastener compresses and at least partially deforms said dome-shaped portion towards juxtaposed contact with said seating member.
In a further aspect, the present invention resides in a torque indicating dome washer for use in a mine or wall support system the washer comprising a generally dome-shaped portion extending generally axially forward from a peripheral edge, said dome-shaped member having a radius of curvature selected such that the application of a selected compressive force axially thereon produces partial radial deflection of said peripheral edge, and at least one flange portion extending radially outwardly from said peripheral edge of said dome-shaped portion, wherein the partial radial deflection of said peripheral edge produces a compressive strain on said flange portion to distort or deform said flange portion.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference may now be had to the following detailed description taken together with the accompanying drawings in which:
Figure 1 illustrates schematically a conventional mine roof support system in an installed configuration in a rock complex;
Figure 2 illustrates a schematic perspective plan view of a torque indicating dome washer in accordance with a preferred embodiment of the invention;
Figure 3 illustrates a cross-sectional view of the dome washer shown in Figure 2 taken along line 3-3';
Figure 4 illustrates an enlarged schematic plan view of the torque indicating dome washer of Figure 2;
Figure 5 illustrates an exploded view showing the installation of the dome washer of Figure 2 as part of a mine roof support system used in the support of a rock complex;
Figure 6 illustrates a cross-sectional side view of the torque indicating dome washer of Figure 2 in an initial installed position next to a spherical seat used in the support system of Figure 5;
Figure 7 illustrates a schematic cross-sectional view of the torque indicating dome washer of Figure 6 following the application of a compressive load by rotating the threaded nut of the mine roof support system of Figure 5 thereagainst with a first predetermined minimum torque;
Figures 8 to 11 show a series of schematic and cross-sectional views of a rock structure, illustrating the installation of the mine roof support and reinforcement system of Figure ~ in accordance with the present invention;
Figure 12 illustrates a schematic perspective view of a threaded nut having a torque indicating washer integrally joined thereto, in accordance with an alternate embodiment of the invention; and Figure 13 illustrates schematically a perspective plan view of a torque indicating washer in accordance with a further embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference is first made to Figure 1 which illustrates a prior art mine roof support system used to consolidate ground movement in a rock complex 8. The support system 10 includes a threaded cast or capped steel dome nut 12 and a steel anchor rod 14. The anchor rod 14 is elongated along its longitudinal axial length, and extends from a threaded outer proximal end portion 16 to an inner distal end portion 18. In the embodiment shown, the distal portion 18 is secured in place in a bore hole 20 formed in the rock complex 8 by a set adhesive resin 22.
In installation, the bore hole 20 is drilled into the rock complex 8 to a desired diameter and depth. A number of two-part resin cartridges (shown as reference numerals 24a,24b in Figure 8) are then inserted into the bore hole 20 ahead of the distal end portion 18 of the steel rod 14. The distal end portion 18 of the rod is next inserted into the bore hole 20 to pierce the cartridges 24a,24b and mix the resin. Optionally, secondary reinforcing components, such as a steel reinforcing plate 26 and/or mesh screen, may be positioned over the projecting proximal end 16 of the rod 14. The nut 12 is then threaded onto the proximal end 16 and tightened against the plate 26 and outer face 30 of the rock complex 8. The tensioning of the nut 12 against the plate 26 compresses the rock complex 8 to provide the desired degree of ground control. If;
however, as a result of inadvertence, the installer over-torques the nut 12, this may result in the tearing out of the rod 14 from the anchoring resin 22, resulting in rod failure, and necessitating the installation of a second anchor rod in an adjacent location.
Figures 2 and 3 illustrate a torque indicating washer 36 for use with the nut I 2, rod 14 and reinforcing plate 26 of the mine roof support system 10 of Figure l, and which is adapted to minimize the likelihood of anchor rod 14 tear out. As will be described, the washer 36 is adapted to be used in conjunction, not only with an anchor rod 14, threaded nut 12 and anchor plate 26, but optionally also a cast steel semi-spherical seat 70 (Figure 5) in the tensioning and ground control of the rock complex 8.
The washer 36 includes a central generally dome-shaped portion 38 which curves forwardly from a peripheral radial edge 40 in a forward direction along axis Ai-A, (Figure 3).
An opening 42 is formed through the axial apex of the dome-shaped portion 38.
The opening 42 is sized marginally greater than the diameter of the rod 14 to enable the washer 36 to be slid over the projecting threaded proximal end 16 of the anchor rod 14 following its placement in a bore hole 20. The dome-shaped portion 46 has a preferred radial diameter d~ of between about 2 and 4 cm, and a radius of curvature of approximately .6 to 1.2.
In the embodiment shown, the dome-shaped portion 46 is stamped from a generally square sheet of 12 gauge steel. The overall size of the sheet is selected such that following its formation, the dome-shaped portion 38 extends substantially to the mid-lateral edges 44 of the washer 36, so as to substantially define four radially projecting generally triangular flange portions 52a,52b,52c,52d integrally formed therewith. Each of the flange portions 52 is formed as a generally planar metal tab or flange which, prior to deformation of the washer 36, are substantially coplanar to each other. Each flange portion 52a,52b,52c,52d further merges along a respective radial quadrant A,B,C,D (Figure 4) with the peripheral edge 40 of the dome-shaped portion 38, and projects outwardly to a radial distance dt outwardly therefrom of between about .7 and 3 cm.
The dome-shaped portion 38 of the torque indicating washer 36 is formed so that the application of a compressive force in the axial direction on the dome-shaped portion 38 results in the initial partial radial outward deflection of the peripheral edge 40, as for example in the direction of arrows 60 (Figure 4). Most preferably, the deflection of the peripheral edge 40 occurs radially about the axis A-A~, and where the compressive force required for deflection is selected as the force directly or indirectly on the washer 36 achieved by tightening the nut 12 along the threaded portion 16 of the rod with a first treated predetermined minimum torque. The first predetermined torque is selected less than the torque necessary to completely deform and flatten the dome-shaped portion 38 and/or result in tear out of the anchor rod 14 from set anchoring resin 22.
In the preferred mine roof assembly 10 shown in Figure S, the dome washer 10 is used in conjunction with a semi-spherical seat 70 which is adapted to translate any tensioning forces at the rock face 30/bore hole 20 interface in a direction generally parallel to the rod axis. The semi-spherical seat 70 is formed as a cast steel member having a planar forward side surface 72, and a generally hemispherical rearward surface 74. A bore hole 76 having a diameter greater than the diameter of the threaded proximal end 16 of the anchor rod 14 extends perpendicularly from the planar surface 74 and through the apex of the hemispherical surface 74. As will be described, the bore hole 76 allows the seat 70 to be slid over the projecting threaded proximal end 16 of the rod 14.
Preferably, the diameter d~ of the dome-shape portion 38 is selected less than the maximum radial diameter ds (Figure 5) of the planar surface 72 of the semi-spherical seat 70, allowing the peripheral surface 40 to be fully supported by the seat 70.
Although not essential, the dome-shaped washer 36 preferably has a maximum width w (Figure 3) from the tip of flange 52a to the tip of the radially opposite flange 52b of about 2 and 6 cm, and which is selected marginally greater than the minimum radial diameter of the threaded nut 12, and more preferably greater than the maximum diameter of the nut 12. As will be described, with this configuration, in installation of the mine roof support system 10 the flange portions 52a,52b,52c,52d project radially outward beyond the nut 12 so as to remain visible during the tightening of the nut 12 along the threaded end 16.
Figures 6 and 7 illustrate best the use of the torque indicating washer 38 as providing the installer with a visual indication when a predetermined minimum torque is first applied on nut 12 in the tensioning of the anchor rod 14. As the nut 12 compresses the washer 36 and is turned with a torque equal to the first predetermined torque, the peripheral edge 40 deforms outwardly.
As the peripheral edge 40 moves radially outward in the direction of arrows 60, the outward deflection of the dome-shaped portion 38 at radially offset locations relative to each of the flanges 52,52b,52c,52d results in the planar flanges distorting and curling forwardly in the direction of arrows 62 (Figure 7). Because of their lateral extent beyond the diameter of the nut 12, the deflection of the flanges 52a,52d is visible readily to the installer.
This deflection enables the installer to determine that the washer plate 26 and spherical seat 70 have been fully seated against the rock face 30 and that the first torque force is being applied on the tightened nut 12.
The visual indication of torque forces on the nut 12 provide the installer with an opportunity to more gradually tighten the nut 12 downwardly against the rock complex 8, minimizing the likelihood that the nut 12 may be over-torqued.
Following the application of the first predetermined minimum torque, the nut 12 is preferably rotated at a second greater torque force to apply a higher compressive axial force on the torque indicating washer 36. The second torque force is preferably sufficient to at least partially and more preferably substantially collapse the dome-shaped portion 38 against the planar surface 72 of the spherical seat 70, as for example is shown in phantom, but which is selected less than the torque force necessary to achieve tear out of the anchor rod 14 from the set resin 22 (Figure 1).
Figures 6 to 11 illustrate best the installation of the mine roof/wall anchoring system 10 utilizing the torque indicating washer 38 of Figure 2. As shown best in Figures 6 and 7, a bore hole 20 is conventionally drilled in the rock complex 8 generally perpendicular to the rock force 30 and to a depth of about 8 feet. A number of resin cartridges 24a,24b are next inserted into the bore hole 20. A conventional steel reinforcing rod 14 having an overall axial length selected approximately two to six inches longer than the bore hole 20 and an externally threaded proximal end portion 14 which extends two to six inches from the proximal endmost tip 66 is next inserted into the bore hole 20. The distal end portion 18 of the rod 14 is slid into the bore hole 20 to rupture the cartridges 24a,24b, releasing the resin therefrom.
The washer plate 26 and semi-spherical seat 70 are then positioned over the portion of the proximal end 16 which extends past the rock face 30. The semi-spherical seat 70 is positioned so that the hemispherical surface 74 of the seat 70 is oriented towards the rock complex 8 and in juxtaposed contact with the plate washer 26. As will be described, with this positioning, the tightening of the nut 12 along the threaded proximal portion 16 results in tensioning forces being substantially maintained axially along the length of the anchor rod 14.
Following the positioning of the reinforcing plate 26 and semi-spherical seat 70, the torque indicating washer 36 is next positioned over threaded proximal end 14.
The washer 36 is slid against the semi-spherical seat 70 so that the dome-shaped portion 38 curves forwardly.
outwardly from the bore hole 20, and with the flanges 52 and peripheral edge surface 40 moved against the planar surface 72.
Next, a capped dome nut 12 which has a releasable cap member 110 secured thereto is threaded onto the end tip 66 of the rod 14, as for example is shown in Figure 10. While the resin remains unset, the dome nut 12 is rotated about the rod axis by means of a power winch, thereby turning the rod 14 about its axial length to mix the released resin. Once the resin has set securing the distal end 18 of the rod 14 in the bore hole 20, the nut 12 is rotated at a high torque force of about 50 to 75 ft.lbs. or less. The higher torque forces on the nut 12 relative to the secured rod 14 results in its deformation and the detachment of the cap member 110 enabling the nut 12 to be run axially along the rod 14 towards the rock face 30.
The tightening of the nut 12 initially slides the plate 26, spherical seat 70 and torque indicating washer 36 to a first position snugly pushed against the rock face 30. As the installer continues to rotate the nut 12 relative to the anchor rod 14, the tightening of the nut 12 provides an axial compressive force on the dome-shaped portion 38 of the washer 36 in the direction of arrows 100 (Figure 7). Once the compressive force equals that applied by the first predetermined minimum torque force on the nut 12, and which most preferably is selected at between about 80 and 125 ft.lbs., the compression of the dome-shaped portion 38 produces a slight outward deflection of the peripheral edge 40. The radial deflection of the edge 40 produces compressive strain at the peripheral edge 40/flange 52 junction as the peripheral edge 40 moves marginally radially outward. The radial outward movement of the peripheral edge 40 thus results in the flange portions 52a,52b,52c,52d deforming forwardly providing the visual indication of the first torque to the installer. Thereafter the installer adjusts the torque forces on the nut 12, and tightens the nut with the second torque force, such that the dome-shaped portion 38 substantially collapses to the flattened position in juxtaposed contact with the planar surface 72 of the spherical seat 70 as is shown in Figure 11.
Although not shown, optionally following the tightening of the nut 12 to the fully seated position of Figure 11, push plates or mesh screening may be affixed to the remaining projecting proximal end 16 of the rod 14 which extends outwardly therefrom in a conventional manner.
Although Figures 2 to 5 illustrate the torque indicating dome washer as comprising a separate component adapted for placement interposed between the semi-spherical seat 70 and nut 12, the invention is not so limited. Figure 12 illustrates an alternate embodiment where like reference numerals are used to identify like components. In Figure 12, a washer nut 120 is provided with a torque indicating washer 32 joined thereto as an integral unit. In Figure 12, the torque indicating washer 38 has essentially the identical construction as that shown in Figure 2.
The washer 32 is spot welded directly to the inner end face 122 of a capped dome nut 12 as a single unit. The torque indicating washer 38 is joined to the dome nut end face 122 with the opening 42 co-axially aligned with a releasable end cap 110 and the threaded interior of the nut 12. Preferably, the dome-shaped portion 38 of the washer 36 is joined to the nut 12 only about the immediate periphery of the opening 42. This construction advantageously ensures that the coupling of the washer 36 to the nut 12 does not adversely affect the outward deflection of the peripheral edge 40, or the compression of the dome-shaped portion 38 upon the application of axial forces. It is to be appreciated that the washer nut 120 of Figure 12, in addition to providing a more compact design, avoids the requirement to separately position the torque indicating washer 36 on the rod 14 ahead of the nut 12.
Although the preferred embodiment of the invention describes the positioning of the plate anchor 26, semi-spherical seat 70, torque indicating washer 36 and tensioning nut 12 following the placement of the anchor rod 14 in the bore hole 20, the invention is not so limited. Tt is to be appreciated that in an alternate construction, the washer plate 26, semi-spherical seat 70, torque indicating dome washer 36 and nut 12 could be prepositioned over the threaded proximal end 16 of the anchor rod 14, prior to the insertion of the distal end 18 in the bore hole 20 and the rupture of the resin cartridges 24a,24b thereby.
Although the preferred embodiment of the invention describes and illustrates the torque indicating washer 36 as having four planar flanges 52a,52b,52c,52d which are integrated with the peripheral edge 40, the invention is not so limited. It is to be appreciated that other flange configurations which are adapted to deform or deflect under a predetermined compressive force are also possible and will now become readily apparent. In addition, the torque indicating washer 36 could be provided with fewer or larger number of different shaped flanges which are adapted to distort under a predetermined axial load without departing from the spirit and scope of the invention. Reference may be had to Figure 13 which illustrates one alternate possible embodiment of the invention wherein like reference numerals are used to identify like components. In Figure 13, the torque indicating washer 36 is provided with only two flanges 52a,52b at radially opposite locations. As with the embodiment described with reference to Figures 2 and 3, the application of an axial compressive force on the dome-shaped portion 38 of the washer 36 results in the deflection of the flanges 52a,52b, to provide the installer with the visual indication that a tensioning nut has been tightened with the first predetermined minimum torque.
Although not essential, more preferably at least the flanges 52a,52b, and in a simplified construction the entire forward surface of the dome washer 36 has a high visibility coating 90 applied thereto. By way of non-limiting example, the high visibility coating 90 could comprise a fluorescent paint selected to provide enhanced visibility of the washer 36 in low light conditions which, for example, would be typically experienced in underground mining operations.
Although the preferred embodiment of the invention describes the securement of the anchor rod 14 in the rock complex bore hole 20 by the use of mixed resin 22, the invention is not so limited. It is to be appreciated that the present invention is equally suited for use with anchor rods which are held in place by means of mechanical anchors including, without restriction, the use of wedge bolts and the like.
Although the detailed description describes the support system 10 as including an anchor rod 14, tensioning nut 12, semi-spherical seat 70, plate anchor 26 and dome washer 36, the invention is not restricted to the specific components. It is to be appreciated that the support system 10 could be provided with fewer or additional components used in concrete wall reinforcement and/or mine roof reinforcement. These components could include without restriction mesh screening, push plates or other components used in conventional support systems provided in place of or in addition to the spherical seat 70 and/or washer plate 26 illustrated in Figure 4.
Although the detailed description describes and illustrates various preferred embodiments, the invention is not so limited. Many modifications and variations will now occur to persons skilled in the art. For a definition of the invention, reference may be had to the appended claims.
Claims (19)
1. A method of installing a mine roof support system in a bore hole formed in a rock face, the support system comprising, an elongated anchor member extending axially from a distal end portion to a threaded proximal end portion, a generally semi-spherical member for placement generally proximate to said rock face, the semi-spherical member having an opening therethrough sized to permit sliding placement of said member over said proximal end portion, and including a generally hemispherical surface portion and a generally planar surface portion, a torque indicating washer having a radially extending peripheral portion and a generally dome-shaped portion which curves convexly forward relative to said peripheral portion and which further comprises a generally centrally positioned aperture sized for enabling placement of said torque indicating washer over said proximal end portion, a threaded fastener sized for threaded coupling with the proximal end portion of the anchor member, the mine support system installed by, inserting the distal end of the anchor member into the rock wall bore hole so that the proximal end projects at least partially outwardly therefrom past said rock face, with the semi-spherical member positioned over the distal end portion such that the hemispherical surface portion faces inwardly and the torque indicating washer positioned over the proximal end portion spaced outwardly from the semi-spherical member and oriented with the dome-shaped portion curving convexly outwardly, rotating the threaded fastener along the proximal portion relative to said anchor rod to move the fastener axially towards initial engagement with the torque indicating washer, applying a first predetermined minimum torque on said threaded fastener to impart a compressive force by said fastener against said torque indicating washer and produce an initial deflection of said peripheral portion to provide a visual indication of said first minimum torque, and applying a second minimum torque on said threaded fastener to compress and at least partially deform said dome-shaped portion towards contact with said planar surface portion of said semi-spherical member.
2. The method as claimed in claim 1 wherein said semi-spherical member and said torque indicating washer are positioned over said proximal end of said anchor member prior to the insertion of said distal end in said bore hole.
3. The method as claimed in claim 1 wherein said second minimum torque is selected greater than said first predetermined minimum torque.
4. The method as claimed in claim 1 wherein prior to inserting the distal end of the anchor member into the bore hole, inserting one or more adhesive resin cartridges into said bore hole, and wherein the subsequent insertion of the distal end of the anchor member into the bore hole ruptures said one or more resin cartridges, and following insertion of said distal end, rotating the anchor member about its axis to mix the resin in the bore hole.
5. The method as claimed in claim 4 wherein said first predetermined minimum torque is selected at between about 100 to 110 ft/lbs, and said second minimum torque is selected at greater than about 130 ft/lbs.
6. The method as claimed in claim 1 wherein the torque indicating washer comprises a dome-shaped portion having a radial diameter which is selected between about 0.5 to 1.5 cm less than a radial diameter of said hemispherical portion.
7. The method as claimed in claim 1 wherein the torque indicating washer has a radial diameter selected greater than a radial diameter of the threaded fastener.
8. The method as claimed in claim 4 wherein said semi-spherical member and said torque indicating washer are positioned over said proximal end of said anchor member after the insertion of said distal end in said bore hole.
9. A method of installing a support system in a bore hole formed in a rock or wall face, the support system comprising, an anchor rod being elongated along an axis from a distal end portion to an externally threaded proximal end portion, a seating member for placement generally proximate to said rock or wall face, the seating member having an opening therethrough sized to permit sliding placement of said seating member over said proximal end portion, a torque indicating washer having a radially extending peripheral portion and a dome-shaped portion which curves convexly forward relative to said peripheral portion and further comprising an aperture therethrough sized for enabling sliding placement of said torque indicating washer over said proximal end portion, a threaded fastener sized for threaded coupling with the proximal end portion of the anchor rod, whereby rotation of said fastener relative to said anchor rod moves the fastener axially along the proximal end portion, the support system being installed by, inserting the distal end of the anchor member into the bore hole so that the proximal end projects at least partially outwardly therefrom past said rock or wall face, with the seating member and torque indicating member positioned over the distal end portion such that the torque indicating member is spaced outwardly from the seating member and in an orientation with the dome-shaped portion curving convexly outwardly, rotating the threaded fastener along the proximal portion relative to said anchor rod to move the fastener axially into engaging contact with the torque indicating washer, wherein the application of a first predetermined minimum torque on said threaded fastener against said torque indicating washer produces an initial outward deflection of said peripheral portion to provide a visual indication of said first minimum torque, and the application of a second minimum torque on said threaded fastener compresses and at least partially deforms said dome-shaped portion towards juxtaposed contact with said seating member.
10. The method of claim 9 wherein said seating member is selected from the group consisting of a push-on plate, a plate washer, a ring washer, a dome washer and a semi-spherical seat, and said seating member and said torque indicating washer are positioned over the proximal end of the anchor rod after the insertion of the distal end in the bore hole.
11. The method of claim 9 wherein said seating member is selected from the group consisting of a push-on plate, a plate washer, a ring washer, a dome washer and a semi-spherical seat, and said seating member and said torque indicating washer are positioned over the proximal end of the anchor rod before the insertion of the distal end in the bore hole.
12. The method as claimed in claim 9 wherein prior to inserting the distal end of the anchor rod into the bore hole, inserting at least one adhesive resin cartridge into said bore hole, wherein the insertion of the distal end of the anchor rod into the bore hole ruptures said at least one resin cartridge, and following insertion of said distal end, rotating the anchor rod about its axis to mix the resin in the bore hole.
13. The method as claimed in claim 12 wherein said first predetermined minimum torque is selected at between about 100 to 110 ft/lbs, and said second minimum torque is selected at greater than about 130 ft/lbs.
14. The method as claimed in claim 9 wherein the torque indicating washer has a high visibility colour applied thereto.
15. A torque indicating dome washer for use in a mine or wall support system the washer comprising a generally dome-shaped portion extending generally axially forward from a peripheral edge, said dome-shaped member having a radius of curvature selected such that the application of a selected compressive force axially thereon produces partial radial deflection of said peripheral edge, and at least one flange portion extending radially outwardly from said peripheral edge of said dome-shaped portion, wherein the partial radial deflection of said peripheral edge produces a compressive strain on said flange portion to distort or deform said flange portion.
16. A torque indicating dome washer as claimed in claim 15 wherein said dome washer comprises a generally square plate having mid-lateral edges, and said dome-shaped portion has a radial diameter selected to extend substantially to the mid-lateral edges of said plate.
17. The torque indicating dome washer as claimed in claim 15 wherein said washer is formed by stamping from a generally planar sheet of steel.
18. The torque indicating dome washer as claimed in claim 17 wherein said flange portion comprises a generally planar metal flange.
19. The torque indicating dome washer as claimed in claim 18 wherein said selected compressive force is equal to a compressive force applied by rotating a nut against said dome washer with a first selected predetermined minimum torque.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2504058 CA2504058A1 (en) | 2005-04-11 | 2005-04-11 | Mine roof support system having torque indicating washer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2504058 CA2504058A1 (en) | 2005-04-11 | 2005-04-11 | Mine roof support system having torque indicating washer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2504058A1 true CA2504058A1 (en) | 2006-10-11 |
Family
ID=37101426
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2504058 Abandoned CA2504058A1 (en) | 2005-04-11 | 2005-04-11 | Mine roof support system having torque indicating washer |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2504058A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014146392A1 (en) * | 2013-03-22 | 2014-09-25 | 中国矿业大学 | Paste fixed-length anchoring supporting method |
| CN106149716A (en) * | 2015-04-28 | 2016-11-23 | 中铁西北科学研究院有限公司深圳南方分院 | The subdivision tensioning system of pressure dispersing anchorage cable |
| EP3748122A1 (en) * | 2019-06-04 | 2020-12-09 | Sandvik Mining and Construction Tools AB | A tension indicator for a rock bolt |
-
2005
- 2005-04-11 CA CA 2504058 patent/CA2504058A1/en not_active Abandoned
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014146392A1 (en) * | 2013-03-22 | 2014-09-25 | 中国矿业大学 | Paste fixed-length anchoring supporting method |
| CN106149716A (en) * | 2015-04-28 | 2016-11-23 | 中铁西北科学研究院有限公司深圳南方分院 | The subdivision tensioning system of pressure dispersing anchorage cable |
| CN106149716B (en) * | 2015-04-28 | 2018-03-20 | 中铁西北科学研究院有限公司深圳南方分院 | The subdivision tensioning system of pressure dispersing anchorage cable |
| EP3748122A1 (en) * | 2019-06-04 | 2020-12-09 | Sandvik Mining and Construction Tools AB | A tension indicator for a rock bolt |
| WO2020245081A1 (en) * | 2019-06-04 | 2020-12-10 | Sandvik Mining And Construction Tools Ab | A tension indicator for a rock bolt |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR100501208B1 (en) | Free running prevailing torque nut | |
| AU721145B2 (en) | Clinch-type fastener member | |
| US4448565A (en) | Stress relieving nut member | |
| US5919006A (en) | Tensionable cable bolt with mixing assembly | |
| US5230589A (en) | Mine roof bolt | |
| EP2257715B1 (en) | Self-attaching female fastener | |
| US5954455A (en) | Combination bolt system | |
| JP2006105400A (en) | Torque resistant fastening element | |
| US9556893B2 (en) | Omnidirectional breakaway support system and connector | |
| US20040028481A1 (en) | Modular helical anchor | |
| EP0804688B1 (en) | Blind fastener and blind fixing method | |
| JPS6018848B2 (en) | expansion anchor | |
| CA2240144C (en) | Low torque threaded fastener and mine roof support system using such a fastener | |
| US5556234A (en) | Mine roof bolt assembly | |
| US5769570A (en) | Cable tensioning dome plate | |
| WO2011156450A2 (en) | Resin-anchored bolt with indentations | |
| CA2504058A1 (en) | Mine roof support system having torque indicating washer | |
| US20120155970A1 (en) | Mine Roof Bolt With End Fitting | |
| WO2006009476A1 (en) | Structural connector | |
| CA2506342A1 (en) | Yieldable cone bolt for use in small diameter bolt holes and method of installing the same | |
| CN1643263A (en) | Bonding anchor | |
| JPH10245898A (en) | Toroidal joint and clamping jig thereof | |
| JP3840285B2 (en) | One side bolt | |
| US20110070048A1 (en) | Crimped cable bolt head and assembly | |
| CA2439397A1 (en) | Mine roof bolt assembly |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |