Patent Application
20090191006
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 to 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.
Accordingly, it would be an improvement in the art to augment or even replace current techniques with simpler devices and devices with permit the use of power tools which apply torque in opposing directions.
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.
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.
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:
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 contemplate an integral wedge barrel used to capture a cable bolt and a threaded sleeve about the cable bolt.
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
As shown in
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
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 39 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.
As depicted in
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 or 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.
