Hollow Rod and Method of Making and Using

This invention relates generally to reinforcing means, and more particularly to a coilable form of reinforcing elements, the elements from several coils being assembled at the job site to form substantially rigid reinforcing rods particularly useful in stabilizing mine roofs and other tunnel or underground chamber roofs.

A conventional machine for installing mine roof bolts uses bolts of a fixed length and requires a considerable amount of head room. For a thick mineral vein which it is desired to mine in several passes of the mining equipment, the mine roof must be rebolted before each pass.

Pultruded continuous fiber reinforced plastic mine roof bolts are disclosed in U.S. Pat. Nos. 4,194,873 and 4,247,224.

In accordance with the invention, coilable reinforcing elements from several coils are assembled into an annular configuration by passage through a die block and into a previously drilled hole at the job site. Less head room is required than for fixed-length bolts. In thick mineral veins, deep holes may be filled with long lengths of the reinforcing material sufficient for several passes of the mining equipment. The reinforcing material is held in place by resin injected between the walls of the drilled hole and the reinforcing material.

The invention is hereinafter described in greater detail with reference to the accompanying drawings in which:

FIG. 1 is a schematic side elevational view of apparatus for producing the coilable reinforcing elements of the invention;

FIG. 2 is an end view of one of the coilable reinforcing elements of the invention;

FIG. 3 is an end view, taken along the line 3--3 of FIG. 1, of a die for forming four ninety-degree coilable reinforcing elements of the invention simultaneously;

FIG. 4 is an end view of a die for forming three one-hundred-twenty-degree coilable reinforcing elements of the invention simultaneously;

FIG. 5 is a fragmentary perspective view of four ninety-degree coilable reinforcing elements of the invention in assembled relationship for forming a substantially rigid reinforcing rod;

FIG. 6 is a schematic side elevational view, partly in section, of apparatus for installing reinforcing elements of the invention in a mine or other underground chamber roof;

FIG. 7 is a schematic perspective view, partly in section, of a portion of the apparatus of FIG. 6; and

FIG. 8 is a schematic perspective view of alternative apparatus for installing reinforcing elements of the invention in a mine or other underground chamber roof.

With reference to the drawings, FIG. 1 shows a plurality of glass filaments 20 being fed from supply packages (not shown) through conventional resin impregnating apparatus 22 including a container 23 having hardenable liquid thermosetting resin 24 therein. The filaments are fed over an upper roller 25, under lower rollers 26 and 27, and over a second upper roller 28, and through a conventional wiper 30 which removes excess resin 24. The filaments 20, after being impregnated with resin 24, are drawn through a heated die 32 which cures the resin while forming the resin-impregnated filaments into rod-like reinforcing elements such as an element 34 shown in end view in FIG. 2. Preferably, the element 34 is generally arcuately shaped, subtends an angle of ninety degrees, and has a tongue 34a on a radial surface at one end and a groove 34b on a radial surface at an opposite end. The die 32 may be provided with a single aperture for making one reinforcing element 34 of indefinite length at a time. Alternatively, the die 32 may have four apertures 32a (FIG. 3) for making four reinforcing elements 34 simultaneously. In another alternative construction, shown in FIG. 4, a die 36 has three apertures 36a for simultaneously producing three arcuate reinforcing elements each subtending an angle of one hundred twenty degrees.

After leaving the heated die 32, the reinforcing elements 34 preferably pass through a rotating groove cutter 38. When the die 32 has four apertures 32a, the four resulting elements 34 are gathered by the cutter 38 into the shape of a hollow rod 40 such as shown in FIG. 5. Each element 34 is provided with a plurality of axially spaced angular grooves 34c on its outer circumferential surface. The grooves 34c are cut in the shape of a helix by the cutter 38, but in use of the rod 40, the elements 34 may harmlessly be axially displaced relative to each other so that the grooves 34c no longer form a helix. As hereinafter explained, the grooves 34c enhance bonding when the rod 40 is installed in a hole and surrounded with resin. After leaving the cutter 38, the elements 34 are separated and each is wound into a separate coil with the smallest windings about two feet in diameter. The coils may be on the same or separate spools.

FIG. 6 illustrates mine or other underground chamber roof 42 into which a hole 42a has been bored and schematically depicts a cart 44 carrying four coils 46, each of which supplies a reinforcing element 34 to a feeding mechanism 48. The feeding mechanism 48 drives a reinforcing rod 40 formed by the elements 34 through a resin injecting nozzle 50 and into the hole 42a. The nozzle 50 and a seal 51 are held in position against the mine roof 42 by a hydraulic actuator 52. Resin and curing agent tanks (not shown) on the cart 44 supply resin and a curing agent to the nozzle 50 through conduits 54 and 55 and pumping means (not shown).

The nozzle 50 and seal 51 are best shown in FIG. 7. The nozzle 50 includes pivotally interconnected halves 50a and 50b which, when closed, provide an annular mixing chamber 50c for the resin and curing agent supplied through conduits 54 and 55, and an annular groove 50d for the seal 51. The mixed resin is injected upwardly along the outside of the rod 40 formed by the reinforcing elements 34. The hollow center 40a (FIG. 5) of the rod 40 serves as a vent for air displaced by the mixed resin. After the resin mixture has hardened sufficiently, the nozzle 50 is removed and the rod 40 is cut off from the supply coils 46. If desired, the seal 51 may be split into two halves and the two halves permanently mounted respectively on the nozzle halves 50a and 50b. The hardened resin mixture forms a bond between the circular wall forming the hole 42a and the rod 40, and the strength of the bond is increased by the resin in the grooves 34c.

The multi-sectioned rod 40 formed from coiled reinforcing elements 34 can also be used with a resin system wherein the resin and curing agent are packaged in separate compartments in a cartridge. FIG. 8 shows a machine 60 including a rotatable platform 62 having four coils 64 of reinforcing elements 34 mounted thereon for the forming of the hollow composite rod 40. The platform 62 is supported on a housing 66 and driven by a motor 68 therein. With a resin cartridge inserted in a hole such as the hole 42a, the rod 40 can be fed into the hole and rotated by rotation of the platform 62 to mix up the resin and curing agent of the cartridge after puncturing the cartridge.

The invention is not limited to the shape shown for the rod 40 or to the number and shape shown for the reinforcing elements 34. The invention lies in the structure and method of use of a plurality of coilable reinforcing elements which can be assembled into a reinforcing rod which could not be coiled if it were in one piece with respect to its cross section.

Various modifications may be made in the structure shown and described without departing from the spirit and scope of the invention.