Resin Mixing and Cable Tensioning Device and Assembly for Cable Bolts

Abstract

The present invention is directed to a device and assembly for the anchoring and tensioning of cable bolts used in earthen formations to stabilize the earthen structures to prevent or minimize the caving in or sluffing-off of the earthen structure. The new invention presents an integral wedge barrel and threaded sleeve which can be turned to facilitate both the mixture of cementing resins and the physical tensioning of an anchored cable and which can reduce or prevent undesirable twisting of the cable during tensioning.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a device and assembly for cable bolt systems. In particular, the present invention relates to cable bolt apparatus which can be used to both mix associated cable resin and to tension the cable bolt assembly against a bearing plate.

2. Background and Related Art

Steel bolts and cable bolts are commonly used in underground mines to stabilize geologic layers adjacent mine openings. For example, cable bolt assemblies are used to secure the geologic layers of the roof of a mine tunnel or drift to prevent roof strata from falling and causing obstructions or injury to persons or equipment in the tunnel.

Rigid members such as steel rods or rebar have long been used in anchoring systems in construction applications and as rock bolts in mining applications. For example, threaded rebar manufactured and sold by DYWIDAG under the brand name Threadbar has been used for rock bolts for years. Anchoring such rods or rebar at one end or at both ends allows the rod to bear a tension load. Steel rods have been particularly useful in anchoring applications because threads can be formed on the outer surface of the rods to receive desired bolts with corresponding threads or to receive other fastening devices such as a Frazer-Jones D9 expansion shell assembly. Rigid steel rods are, however, not always ideal because they are manufactured in finite, fixed lengths and long rods are often difficult to work with in confined spaces such as construction and mining sites. Rigid rods can also be subject to shearing stresses if, for example, there is ground movement adjacent the rod in a mining application.

Steel cables comprising multiple strands of steel have also been used as anchoring systems. Unlike rigid, steel rods, cables provide some flexibility along their length. That is, a cable can bent around an object or deflect when subject to ground movement adjacent the cable. In some instances, steel cable is easier to use in confined spaces. Historically, anchoring a cable at one or both ends is more difficult because the cable does not bear threads to receive bolts. A number of cable anchoring methods have been used. One example is a multistrand anchorage device which separates strands of the cable and anchors each strand individually or in groups such as the DYWIDAG Multistrand Posttensioning System. Another example comprises positioning a thread-bearing sleeve along the length of the cable at the desired locations to receive a desired bolt or Frazer-Jones D9 expansion shell assembly.

Another example includes unraveling the cable and sliding a ring over and down along the center or king wire of the cable to a desired location and then rewinding the cable. In this way, a bulge or ‘bird cage’ is formed in the cable due to a spreading of the wires in the area of the ring. The bulge or spreading of the wires permits resin used with the cable to permeate into the cable to enhance anchorage of the cable upon the setting of the resin. If mechanical anchorage is also desired, an additional thread-bearing or thread-like-bearing apparatus must still be added if a desired bolt or Frazer-Jones D9 expansion shell assembly is to be used.

A number of devices rely upon a thread-bearing sleeve being disposed about the cable or other threaded systems to tension a cable. The sleeve is positioned relative to the cable or other threaded systems which are used to tension the cable including:

(1) placing a threaded tube and clamping it on the cable;

(2) threading the cable itself;

(3) placing and securing the cable inside a threaded bar such as a DYWIDAG threadbar® with a hole in it; and

(4) using a threaded insert which is placed over the king wire and then threaded inside a Frazer-Jones D9 expansion shell assembly.

A number of cable and other bolt assemblies are known, including those taught by U.S. Pat. Nos. 2,667,037, 3,077,809, 4,509,889, 4,954,017, 4,984,937, 5,015,125, 5,026,517, 5,215,411, 5,230,589, 5,259,703, 5,375,946, 5,378,087, 5,441,372, 5,458,442, 5,525,013 and others.

These techniques include drilling a long hole into the earthen geology which is to be stabilized. A requisite amount of multi-component epoxy resin is placed in the hole at the desired location. The steel cable is also placed in the hole. A machine is used to spin the cable thereby mixing the multi-component epoxy to cause the chemical reaction between the multi-components. The epoxy sets and anchors the cable in the hole.

Known techniques for mixing multi-component epoxy include mechanical devices designed to spin the cable at a relatively low torque to mix the epoxy components followed by tensioning the cable using increased torque after the cable is cemented in place. The mechanical devices include known and available domed nuts, crimped bolts, perpendicular roll pins, shear pins, weld beads, and keys ways which permit spinning a nut or other structure on a threaded sleeve at a low torque without compromising or defeating the ability of the domed nuts, crimped bolts, perpendicular roll pins, shear pins, weld beads, and keys ways to at least temporarily fix the relative position of the nut and threaded sleeve affixed to the cable. In this way, the spinning of the cable mixes the epoxy resin components. After the cable is cemented in place, a higher torque is then applied, typically in the same direction as the low torque, to tension the cable which use of higher torque does compromise or defeat the ability of the domed nuts, crimped bolts, perpendicular roll pins, shear pins, weld beads, and keys ways to fix the relative position of the nut and threaded sleeve.

When tensioning a steel cable, it is not uncommon for the cable itself to twist somewhat between the point of application of torque for tensioning and the point at which the cable is cemented in place. This can cause a slight decrease in the length of the cable. Upon release of the torquing device the cable can untwist thereby returning to its longer repose length and causing an undesirable decrease in the tension on the cable.

Accordingly, it would be an improvement in the art to augment or even replace current techniques with simpler devices and devices which permit the use of power tools which apply torque in opposing directions and avoid unwanted decrease in tensioning of the cable after removal of the torquing tool.

SUMMARY OF THE INVENTION

The present invention relates to an integral wedge barrel and threaded sleeve which can be used for both spinning to mix epoxy resin and used to tension a cable bolt.

The present invention contemplates a unitary or integral wedge barrel and threaded sleeve with a rotatable nut about the threaded sleeve. The threaded sleeve is disposed in an aperture of a bearing plate. A cable is disposed through the threaded sleeve and through the wedge barrel. The cable is fixed in place relative to the wedge barrel by common barrel wedges. When assembled the cable is fixed relative to the wedge barrel. The threaded sleeve is fixed relative to the barrel because the threaded sleeve and wedge barrel are either manufactured as one integral unit or are joined together in a fixed relationship by means of welding or some other common joining practice.

In use, the device permits reliable mixing of epoxy resin components by rotating the nut until it abuts the wedge barrel whereupon the cable will spin in the direction the nut is being turned. This turning or spinning action can be used to mix the epoxy resins.

In some applications, after the epoxy resin is set and the cable cemented in place, the nut may be turned or spun in the opposite direction causing the nut to move away from the wedge barrel and move toward the opposing bearing plate against which the nut can be forced by applying high torque to the nut whereby the cable is put under tension. In other applications it may be necessary to use known techniques thereby turning the cable in the same direction for both mixing and tensioning.

The bearing plate may comprise one or more projections or protrusions from the face or edge of the bearing place toward the surface against which the bearing place is disposed. This provides points of contacts between the bearing plate and for example an earthen or rock surface to reduce or prevent the bearing place resting against a surface from spinning when the cable is being tensioned.

The structure of the aperture of the bearing plate and the threaded sleeve disposed in the aperture permit the threaded sleeve to slide through the bearing plate to permit tensioning while at the same time reducing or preventing any twisting of the cable-bearing threaded sleeve within the aperture.

While the methods and processes of the present invention have proven to be particularly useful in the area of cable bolt tensioning, those skilled in the art can appreciate that the methods and processes can be used in a variety of different applications and in a variety of different areas of manufacture to yield an equivalent device.

These and other features and advantages of the present invention will be set forth or will become more fully apparent in the description that follows and in the appended claims. The features and advantages may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. Furthermore, the features and advantages of the invention may be learned by the practice of the invention or will be obvious from the description, as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the manner in which the above recited and other features and advantages of the present invention are obtained, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. Understanding that the drawings depict only typical embodiments of the present invention and are not, therefore, to be considered as limiting the scope of the invention, the present invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

FIG. 1 illustrates a perspective view of one embodiment of the device and system that provides a suitable structure and function for the present invention;

FIG. 2 illustrates a cross-sectional view of an embodiment of the present invention;

FIG. 3 illustrates a cross-sectional view of an embodiment of the present invention;

FIG. 4 illustrates use of the present invention with a breakaway view of a cable cemented into a geological formation.

FIG. 5 illustrates a perspective view of another embodiment of the bearing plate;

FIG. 6 illustrates a perspective view of another embodiment of the a threaded sleeve with at least one flatten side;

FIG. 7 illustrates a cross-sectional view of another embodiment;

FIG. 8 illustrates a cross-sectional view of another embodiment;

FIG. 9A illustrates a partial cross-sectional view along line A of FIG. 8 depicting the relationship between a bearing plate and a threaded sleeve;

FIGS. 9B, 9C and 9D illustrate partial cross-sectional views of alternative embodiments of FIG. 9A;

FIG. 10 illustrates use of another embodiment of the present invention with a breakaway view of a cable cemented into a geological formation.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a device for use in anchoring and tensioning cables or cable bolts to stabilize walls or ceilings in earthen bodies such a mines or other underground openings. In particular, the present invention is directed to a integral device which both facilitates mixing the epoxy resins used to anchor the cable bolt in the earthen body and tensioning the cable bolt after it is anchored in place. The present invention contemplates an integral wedge barrel used to capture a cable bolt and a threaded sleeve about the cable bolt.

FIG. 1 and the corresponding discussion are intended to provide a general description of one embodiment of the present invention. One skilled in the art will appreciate that the invention may be practiced by one or more embodiments in a variety of configurations. Mixing and tensioning assembly 10 is shown in perspective view. Assembly 10 comprises cable or cable bolt 20, an integral body 30 of a wedge barrel and threaded sleeve disposed about cable bolt 20, nut 40 disposed along integral body 30 and bearing plate 50. Cable bolt 20, nut 40 and bearing plate 50 are all commonly known, used and available cable bolt components.

As depicted in FIG. 2, device or integral body 30 comprises a wedge barrel end 32 defining sloped interior surface 34 to receive a plurality of wedges 36. Integral body 30 further comprises a threaded sleeve portion 38. While the preferred embodiment contemplates integral body 30 being a continual unitary member, a person of skill in the art would recognize that other embodiments would contemplate an interface between a wedge barrel and a threaded sleeve achieved via a weld between a wedge barrel and a threaded sleeve, via a recessed barrel with a mating surface corresponding to a mating end of a threaded sleeve, via screwing the threaded sleeve into the wedge barrel, or via prongs on one end of the threaded sleeve engaging apertures in the wedge barrel, all to fix the interrelationship between the wedge barrel and the threaded sleeve. The result in all embodiments being a interdependent wedge barrel and threaded sleeve which when either part is acted upon by a force the same or substantially similar force is also transmitted to the other part of the integral body 30.

Cable bolt 20 is disposed within integral body 30. As is commonly known in the art, wedges 36 disposed between cable bolt 20 and wedge barrel 32 act by friction and/or other forces to fix cable bolt 20 within integral body 30 such that force along bolt 20 is transmitted to integral member 30 and vice versa.

Nut 40 is disposed along a length of body 30 between wedge barrel portion 32 and bearing plate 50. Nut 40 can be turned in both directions. As shown in FIG. 2, when nut 40 is turned until it abuts wedge barrel 32, then upon abutting wedge barrel portion 32, further turning of nut 40 will cause both body 30 and bolt 20 to turn or spin in the same direction. This spinning can be used to spin cable bolt 20 to mix epoxy resins as discussed below.

As shown in FIG. 3, nut 40 can also be turned in the opposite direction until it abuts bearing plate 50, or one or more optional washers 60 constructed of metal and/or HDEP, Teflon, nylon, or similar materials to reduce friction. As known in the art, plate 50 may be dome-shaped. Bearing plate 50 defines a plate aperture 52 to permit plate 50 to move independent of body 30. Similarly, optional washer 60 defines a washer aperture 62 to permit washer 60 to move independent of body 30. Upon abutting plate 50 or washer 60, continued turning or spinning of nut 40 in the same direction puts a force upon plate 50 thereby putting cable bolt 20 in tension as plate 50 is forced against a geologic formation such as rock, dirt or mineral. It will be appreciated that threaded sleeve portion 38 is of a sufficient length to permit tensioning and, as needed, retensioning of cable bolt 20. Threaded sleeve portion 38 may be about twelve inches or longer or shorter depending on the geologic conditions of use.

The present invention permits universal use of assembly 10. For example, when sleeve threads are right-handed threads as is typical in coal mines, tools are used that are able to turn nut 40 in either direction as depicted in FIGS. 2 and 3.

When sleeve threads are left-handed threads as is typical in hard rock mines, jack-legs are typical tools used to turn nuts 40 but are able to turn nut 40 in only one direction to force nuts 40 against bearing plates 50. When tools such as unidirection jack-legs are used, the present invention further comprises means for providing a temporary, fixed interface between nut 40 and threaded sleeve portion 38. The temporary, fixed interface between nut 40 and threaded sleeve portion 38 can be accomplished by known techniques previously discussed including but not limited to known frictional interfaces, weld beads, roll pins, keyway with keys, buggered threads, domed nuts, or crimped sleeves. As a result, turning of nut 40 also turns sleeve portion 38 which turns cable 20. This commonly known unidirection turning of nut 40 can be used to both mix epoxy resins at a lower torque and then at higher torque to overcome, break or shear the temporary, fixed interface to place bolt 20 under tension.

An optional sleeve cover, not shown, extends along the length of threaded portion 39 from nut 40 through plate aperture 52 towards the end of portion 38 to protect the threads of portion 38 from being damaged or compromised prior to use. The sleeve cover is disposed about threaded portion 38 and can comprise plastic, soft metal, rubber, cardboard or any other suitable material capable of protecting the threads of sleeve portion 38 from damage prior to use.

Embodiments of the present invention may comprise other structural features. Bearing plate 50 may comprise one or more projections or protrusion toward the bearing surface. For example, FIGS. 5 and 7 depict projections 54 which may imbed into or catch onto the bearing surface or onto or into appliances such as metal mesh upon a bearing surface. In place, projections 54 reduce or prevent bearing plate 50 from spinning when torque is applied to tension the cable. As depicted in FIG. 8, alternative projections or protrusions 56 may be employed. Projections 56 could be prepared by casting, machining or by adding material to plate 50 such as by welding. FIG. 8 also depicts other alternative projections 57 which may be formed by a punching or stamping process during manufacture of plate 50. In all cases, projections 54, 56 or 57 act to engage the surface or surfaces against which bearing plate 50 is positioned to reduce or prevent movement or spinning of plate 50.

Threaded member 38 may comprise one or more exterior shapes with a corresponding, opposing and mating shape in the aperture 52 of bearing plate 50, all designed to permit threaded member 38 to slide through aperture 52 of plate 50 but also reduce or prevent threaded member 38 from spinning within aperture 52. For example, FIG. 6 depicts threaded member 38 with flattened side 39. FIG. 9A depicts a corresponding, opposing flattened aperture wall 58 of plate 50 which mates with surface 39. FIG. 9B depicts another illustrative embodiment comprising threaded member 38 with two flattened side walls 39 within two corresponding, opposing flattened aperture walls 58 which mate with surfaces 39. FIG. 9C depicts another illustrative embodiment comprising threaded member 38 with keyway 39 with a corresponding, opposing key projection 58 of plate 50 projecting into keyway 39 which mates with surface 39. FIG. 9D depict another illustrative embodiment comprising an alternative threaded member 38 with keyway 39 with a corresponding, opposing key projection 58 of plate 50 projecting into keyway 39 which mates with surface 39. These embodiments are merely illustrative of one or more opposing surfaces 39 and 58 which permit member 38 to pass through plate 50 but reduce or prevent member 38 from turning or spinning independent of member 38's relationship to or position in plate 50. One skilled in the art may recognize other such structures. The structure and function of embodiments illustrated in FIGS. 9A-D are examples of means for substantially preventing the rotation of threaded member 38 and cable 20 when disposed through plate 50.

The structure and function of embodiments illustrated in FIGS. 9A-D combined with projections 54, 56, or 57 are examples of means for substantially preventing the twisting of cable 20 during tensioning. That is, the means for substantially preventing the twisting of cable 20 during tensioning reduces or prevents the undesirable twisting, shortening and/or lengthening of cable 20 during or after tensioning. The present invention reduces or prevents back-spin of the cable after release from the torquing tool. These devices and techniques may also be used in certain mining operations that use cement grouting systems which require no mixing but utilize similar tensioning of a cable.

As depicted in FIGS. 4 and 10, the subject wall, roof, or floor of a geologic structure 70 is drilled to create drill hole 72. Epoxy resin components are placed in hole 72 at the desired location. Assembly 10, preassembled and comprising cable 20, body 30, nut 40 and bearing plate 50 is placed such that cable 20 is inserted into hole 72 to a depth so a portion of cable 20 is inserted through or adjacent the epoxy resin components in hole 72. Nut 40 is turned in the desired direction causing cable 20 to spin in hole 72 to mix the epoxy components to create a epoxy resin or cement 80 which acts to anchor cable 20 in hole 72. Cable 20 is thrust into hole 72 to the desired depth with the entire device 10 thrust against wall 70 and held in place until the resin sets. After the resin or cement is set and cable 20 is anchored in hole 72, nut 40 is again turned in the desired direction to further force nut 40 against bearing plate 50, or washer 60. This pushes plate 50 against wall 70 putting cable 20 under tension. The appropriate tension is placed upon cable 20 to help stabilize wall 70. After tensioning, the preferred installation contemplates removing the thrust force by withdrawing the tensioning tool about one quarter inch away from the washer 60 or plate 50 to ensure that the tool is not experiencing friction loss against the washer 60 or plate 50 and nut 40 is again turned for further tensioning. A plurality of assemblies 10 are used over an area to prevent geologic structures 70 from caving in and causing injury to persons or equipment.

The devices depicted in FIGS. 5-10 provided the added advantage of having bearing plate 50 affirmatively engage wall 70 or any appliance thereon via projections 54, 56, or 57 to reduce or prevent movement of plate 50 vis-à-vis wall 70. When torque is applied to tension cable 20, member 38 may move laterally through plate 50 in the direction of the cable as needed for tensioning. However, because of surfaces 39 and 58 member 38 is not permitted to spin or rotate within aperture 52 of plate 50. As a result, cable 20 is held in a relatively fixed orientation to wall 70 thereby reducing or preventing twisting of cable 20 between the point of application of torque for tensioning and the point of cementation or anchorage in wall 70 during or after tensioning.

While the Figures only depict a single cable comprising a plurality of wound or twisted wires, the present invention also contemplates assembly 10 being capable of receiving and securing a number of cables 20 as illustrated in U.S. Pat. No. 5,525,013.

Thus, as discussed herein, the embodiments of the present invention embrace an assembly 10 comprising a device which can be turned to facilitate both mixing resin or cement to anchor cable 20 and to put cable 20 under the desired tension to secure the adjacent surface.

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. A cable bolt tensioning device comprising: an integral wedge barrel and threaded sleeve configured to receive a cable, the threaded sleeve disposed in an aperture of a bearing plate; and means for substantially preventing the rotation of the cable in the aperture.

2. The device of claim 1 further comprising wedges disposed within the wedge barrel.

3. The device of claim 1 wherein the bearing plate comprises one or more projections to engage an adjacent surface.

4. The device of claim 1 wherein the means for substantially preventing the rotation of the cable in the aperture comprises mating surfaces of the threaded sleeve and of the aperture of the plate wherein the mating surface of the threaded member is a substantially flat surface.

5. The device of claim 1 wherein the means for substantially preventing the rotation of the cable in the aperture comprises mating surfaces of the threaded sleeve and of the aperture of the plate wherein the mating surface of the threaded member is a keyway into which a portion of plate projects.

6. A cable bolt assembly comprising: an integral body comprising wedge barrel and threaded sleeve configured to receive a cable;a bearing plate defining an aperture therethrough, the threaded sleeve disposed in the aperture;one or more cables disposed within the integral body;wedges disposed within the wedge barrel between the wedge barrel and the cable(s); anda nut disposed about the threaded sleeve, the nut having threads compatible with the threaded sleeve; andmeans for substantially preventing the rotation of the cable(s) in the aperture.

7. The assembly of claim 6 further comprising a bearing plate disposed about the threaded sleeve such that the nut is disposed between the integral body and the bearing plate.

8. The assembly of claim 6 further comprising one or more washers disposed about the threaded sleeve portion between the nut and the bearing plate.

9. The assembly of claim 6 further comprising a sleeve cover disposed along a length of the threaded sleeve.

10. The device of claim 6 wherein the bearing plate comprises one or more projections to engage an adjacent surface.

11. The device of claim 6 wherein the means for substantially preventing the rotation of the cable in the aperture comprises mating surfaces of the threaded sleeve and of the aperture of the plate.

12. The device of claim 11 wherein the mating surface of the threaded sleeve is a substantially flat surface.

13. The device of claim 11 wherein the mating surface of the threaded sleeve is a keyway into which a portion of plate projects.

14. A cable bolt assembly comprising: an integral wedge barrel and threaded sleeve configured to receive a cable, the threaded sleeve disposed in an aperture of a bearing plate; andmeans for substantially preventing the twisting of the cable during tensioning.

15. The device of claim 14 wherein the bearing plate comprises one or more projections at or near the periphery of the plate to engage an adjacent surface.

16. The device of claim 14 wherein the means for substantially preventing the twisting of the cable during tensioning comprises mating surfaces of the threaded sleeve and of the aperture of the plate combined with one or more projections on the learning plate, wherein the mating surface of the threaded sleeve is a substantially flat surface.

17. The device of claim 14 wherein the means for substantially preventing the twisting of the cable during tensioning comprises mating surfaces of the threaded sleeve and of the aperture of the plate combined with one or more projections on the learning plate, wherein the mating surface of the threaded sleeve is a keyway into which a portion of the plate projects.