FIELD OF THE INVENTION The present invention is related to industrial anchorage bolts which are widely used in several industrial fields, particularly in the mining industry to reinforce and support rock. Generally, the bolts are inserted into bore holes and anchored in place by a chemically reactive grouting that hardens in the space between the anchorage bolt and the bore hole wall. The present invention is specifically targeted at but not limited to hollow or tubular mine support bolts.

BACKGROUND OF THE INVENTION The most common mine roof support system is the use of"headed rebar"bolts with polyester resin grouting. The bolts are made by forging a square head on standard steel rebar. The pattern on the rebar is typically an"X"pattern and is designed to provide mechanical"keying"with concrete in construction applications or with the polyester resin grouting in roof bolt applications. The mechanical"keying"

provides exceptional initial strength with minimal movement of the bolt as load is applied. This system was introduced in the early 1970's and continues today. However, once the bolt loads to a point where the shear strength of the resin is exceeded or the shear strength between the resin and bore hole wall is exceeded, roof support will suddenly be lost.

Initially, the characteristics of the deformed tubular bolt and rebar bolt will be very similar as load is applied. The difference will be seen at higher loads. The deformed tubular bolt will actually increase the anchorage strength as load is applied because it places the resin in confined compression, increasing the interfacial strengths. Rebar bolts or non-deformed tubular bolts on the other hand decrease the anchorage strength as load is applied because they place the resin grout in shear and tension decreasing the interfacial strengths.

Figure 25 shows ideally how the deformed bolt performs in comparison to a grooved tube or rebar bolt.

Initially, the smooth deformed bolt will have slightly higher deflections. As the load continues to increase (y axis), both bolts will reach their elastic limit and enter the plastic limit. Failure of the rebar bolt will occur when the resin shears. The holding power will suddenly drop off.

After the resin shears with the standard rebar pattern, the maximum load capability usually falls to 1 to 4 tons which is the force required to move the bolt through the sheared resin grout.

The deformed tubular bolt will continue to absorb energy (hold load) because as it plastically yields it continues to place the resin in compression which increases the interfacial strength of the resin/elongated member and resin/bore hole wall. The greater the interfacial strengths, the better the anchorage. The area under the curves represents the total amount of energy the system will absorb.

The greater the energy capability the better the roof support.

U. S. Patent 4,750, 887 (Simmons 1988) solved the problem of anchorage failure by the use of a solid bolt and nut that placed the resin in confined compression. This system works well and provides a failure mode similar to that shown in figure 25. This system has the disadvantage of only placing the resin grout at the very top of the bolt in compression and not distributing the load along a larger portion of the bolt. With the deformed tubular bolts, the confined compression can be achieved at numerous points along the bolt. In addition, U. S. Patent 4,750, 887 has the disadvantage of requiring treaded components that must work in an abrasive environment and requires a bore hole that is significantly larger than the bolt.

The present invention solves the problem of bolts pulling free from the grouting before the full strength of the bolt is achieved.

SUMMARY OF THE INVENTION The present invention pertains to a mine roof bolt for a grouted bore hole in a roof of a mine. The mine roof bolt comprises an elongated member having a cross-sectional diameter less than that of the bore hole, a first end, and a second end. The elongated member has deformations such that axial tension on the bolt results in axial movement between the elongated member and the grout and results in confined compression of the grout between the bore hole and the elongated member surface to facilitate anchorage of the elongated member with grout to the mine rock in which the bore hole is disposed. The mine roof bolt comprises a flange disposed adjacent to the second end.

The present invention pertains to a method for supporting a mine roof. The method comprises the steps of moving a first end of a mine roof bolt through a grout capsule so grout from the grout capsule flows along the outer surface of an elongated member of the mine roof bolt which has deformations such that axial tension on the mine roof bolt results in axial movement between the elongated member and the grout and results in confined compression of the grout between the bore hole and the elongated member surface to facilitate anchorage of the mine roof bolt with the mine roof when the grout between the elongated member and the mine roof sets. There is the step of allowing the grout to set so the mine roof bolt is anchored to the mine roof in the bore hole.

The present invention pertains to a method of making a mine roof bolt. The method comprises the steps of placing an elongated member in a secure position. There is the step of forming deformations in the elongated member such that axial tension on the elongated member results in axial movement between the elongated member and the grout and results in confined compression of the grout between the bore hole and the elongated member surface to facilitate anchorage of the elongated member with grout to the mine rock in which the bore hole is disposed.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings, the preferred embodiment of the invention and preferred methods of practicing the invention are illustrated in which: Figure 1 is a schematic representation of a mine bolt of the present invention.

Figure 2 is a bottom view of the mine bolt having a cross-section with at least one flat side.

Figure 3 is a schematic representation of a cross- section of the tube of the mine bolt having a closed perimeter.

Figure 4 is a schematic representation of a cross-section of a first end of the tube with a plug.

Figure 5 is a schematic representation of a cross- section of the first end with a cap.

Figures 6,7 and 8 are schematic representations of deformations in the tube with confined compression between the tube and the resin.

Figure 9 is a schematic representation of a cross- section of a C-shaped tube filled with material.

Figure 10 is a schematic representation of a spiral tube.

Figure 11 is a schematic representation of a cross-section of a tube which is not welded.

Figure 12 is a schematic representation of a cross-section of a C-shaped tube.

Figure 13 is a schematic representation of a J-hook in the mine bolt.

Figure 14 is a schematic representation of an anchor bolt in the mine.

Figure 15a is a schematic representation of a tube having orthogonal crimps with a paddle end.

Figure 15b is a schematic representation of a top view of the paddle end of the tube of figure 15a.

Figure 16a is a schematic representation of a tube having orthogonal crimps with a cross end.

Figure 16b is a schematic representation of a top view of the cross end of the tube of figure 16a.

Figure 17a is an alternative embodiment of a tube having a swaged straight pattern with a cross end.

Figure 17b is a schematic representation of a top view of the cross end of the tube of figure 17a.

Figure 18a is a schematic representation of a tube having a swaged cone pattern with a cross end.

Figure 18b is a schematic representation of a top view of the cross end of the tube of figure 18a.

Figure 19 is a schematic representation of a side view of the tube with deformations.

Figure 20 is a schematic representation of another side view of the tube with deformations.

Figure 21 is a sectional view of figure 20.

Figure 22 is a sectional view of figure 20.

Figure 23 is a sectional view of figure 21.

Figure 24 is a schematic representation of the mine bolt having an elongated member made of rebar.

Figure 25 is a graph of confined compression failure versus resin shear failure.

DETAILED DESCRIPTION Referring now to the drawings wherein like reference numerals refer to similar or identical parts throughout the several views, and more specifically to figure 1 thereof, there is shown a mine bolt 10 for a grouted bore hole 12 in a roof 14 of a mine. The mine bolt 10 comprises an elongated member, for example a tube 16 or a solid rod, such as rebar 44 as shown in figure 24, having a cross- sectional diameter less than that of the bore hole 12, a first end 20, and a second end 22. The elongated member has deformations 30 such that axial tension on the bolt results in axial movement between the elongated member and the grout 32 and results in confined compression of the grout 32 between the bore hole 12 and the elongated member surface to facilitate anchorage of the elongated member with grout 32 to the mine rock in which the bore hole 12 is disposed. The mine bolt 10 comprises a flange 24 disposed adjacent to the second end 22.

Preferably, the elongated member has deformations 30 such that increasing axial tension increases anchorage strength of the elongated member with the mine roof 14. The deformations 30 preferably form wedges 34 in the elongated

member that compress the grout 32 and places the elongated member in radial/hoop compression when the elongated member experiences axial tension, as shown in figures 6,7 and 8.

Preferably, the elongated member's surface is relatively smooth so that slip will occur between the elongated member and grout 32 and not between the grout 32 and the bore hole 12.

The deformations 30 preferably have an angle in the elongated member relative to the elongated member's longitudinal axis less than 45 degrees. Preferably, each deformation 30 has a sloped portion which has the angle in the elongated member relative to the elongated member's longitudinal axis less than 45 degrees. The deformations 30 preferably have a depth of 1% to 40% of the elongated member's diameter.

Preferably, the bolt includes a bearing plate 26 adapted to be disposed between the flange 24 and the roof surface 28 when the elongated member is in place in the bore hole 12. The flange 24 preferably holds the bearing plate 26 against at least 10,000 lbs. of load. Preferably, the elongated member is a tube 16 that has a hollow interior 18, as shown in figure 3. The first end 20 is preferably closed.

The second end 22 is preferably open, but can be closed also.

See U. S. Patent 5,387, 060 (Locotos), incorporated by reference herein. Preferably, the tube 16 has a circular cross-section, as shown in figure 3, or has at least one flat side, as shown in figure 2. The tube 16 preferably has a closed perimeter.

Preferably, the flange 24 is formed from the tube 16, and the flange 24 and the tube 16 are one continuous piece, as shown in figures 19-23. The bolt can include a plug 36 that is disposed in proximity to the first end 20 to close the first end 20 of the tube 16, as shown in figure 4.

Preferably, the bolt includes a cap 38 that fits to the first end 20 to close the first end 20 of the tube 16, as shown in figure 5.

The tube 16 preferably has a maximum cross- sectional dimension less than that of the diameter of the bore hole 12 and a minimum cross-sectional area of 45% of the cross-sectional area of the bore hole 12. Preferably, the second end 22 has either a round, square, hexagon or octagon shaped cross-section. The tube 16 is preferably made from steel. Preferably, the inside of the tube 16 is coated or filled to reduce corrosion, as shown in figure 9.

The tube 16 can be a metal sheet rolled into a spiral, as shown in figure 10. Alternatively, the tube 16 has a first edge and a second edge spaced from the first edge, as shown in figure 11. The tube 16 can have a cross- sectional shape of a C, as shown in figure 12. The elongated member can include a solid rod.

The present invention pertains to a method for supporting a mine roof 14. The method comprises the steps of moving a first end 20 of a mine bolt 10 through a grout capsule 56 so grout 32 from the grout capsule 56 flows along the outer surface of an elongated member of the mine bolt 10

which has deformations 30 such that axial tension on the mine bolt 10 results in axial movement between the elongated member and the grout 32 and results in confined compression of the grout 32 between the bore hole 12 and the elongated member surface to facilitate anchorage of the mine bolt 10 with the mine roof 14 when the grout 32 between the elongated member and the mine roof 14 sets. There is the step of allowing the grout 32 to set so the mine bolt 10 is anchored to the mine roof 14 in the bore hole 12.

Preferably, after the moving step, there is the step of rotating the elongated member of the mine bolt 10 disposed in the bore hole 12 from a second end 22 of the elongated member with a bolting machine connected to an insertion tool that contacts the second end 22. The moving step preferably includes the step of inserting the elongated member into the bore hole 12 until a bearing plate 26 in contact with a flange 24 of the mine bolt 10 in proximity to the second end 22 contacts the surface of the mine roof 28.

Preferably, there is the step of increasing axial tension on the mine bolt 10 to increase anchorage strength of the mine bolt 10 in the bore hole 12.

The increasing the axial tension step preferably includes the step of compressing the grout 32 and placing the elongated member in compression with wedges 34 of the deformations 30 in the elongated member. Preferably, increasing the axial tension step includes the step of slipping the elongated member relative to the grout 32 and not the grout 32 relative to the bore hole 12. The moving

step preferably includes the step of moving the first end 20 of a tube 16 which is closed through the grout capsule 56 so grout 32 from the grout capsule 56 will not enter the interior 18 of the tube 16 but flow along the outer surface of the tube 16 which has deformations 30 such that axial tension on the bolt results in axial movement between the tube 16 and the grout 32 and result in confined compression of the grout 32 between the bore hole 12 and the tube 16 surface to facilitate anchorage of the tube 16 with the mine roof 14 when the grout 32 between the tube 16 and the mine roof 14 sets.

The present invention pertains to a method of making a mine bolt 10. The method comprises the steps of placing an elongated member in a secure position, such as a vise. There is the step of forming deformations 30 in the elongated member such that axial tension on the elongated member results in axial movement between the elongated member and the grout 32 and results in confined compression of the grout 32 between the bore hole 12 and the elongated member surface to facilitate anchorage of the elongated member with grout 32 to the mine rock in which the bore hole 12 is disposed.

In the operation of the invention, distortions of the cylindrical bolt shape are employed so that any axial movement (deflection) of the bolt in the grout 32 will result in confined compression of the grout 32 between the bore hole 12 and bolt surface. To achieve maximum strength multiple distortions may be made along the length of the bolt in the

grouted area. The bolt surface distortions should be made in such a way that axial tension on the bolt head will result in axial movement between the bolt and the grout 32 before axial movement between the grout 32 and the bore hole 12 in the area of the distortions.

The advantage of deformations 30 in the bolt are as follows.

Bolts do not slip out of grout 32 before full strength of the bolt is recognized Increasing axial tension increases anchorage strength Higher grout 32/bore hole 12 interfacial strength under load Increased amount of energy required to break or remove bolt, thus providing safer anchorage The deformations 30 can be used in any anchorage system that uses a grouted bolt. Some examples include but are not limited to mine roof 14 support, tunneling, industrial construction and concrete anchorage.

Deformations 30 of a smooth cylindrical bolt (tubular or solid) are employed so that axial movement of the bolt will create confined compression of the grout 32 between the bore hole 12 and bolt surface. Deformations 30 should be made perpendicular to the axis of the bolt in such a way that they cause an increase in the diameter of tube 16

perpendicular to both the deformation 30 direction and the bolt axis. It is preferred to have multiple deformations 30 along the length of the bolt in the grouted area. It is most preferred that consecutive distortions are in perpendicular directions.

Substantial improvement in the strength of anchorage bolts can be achieved by deforming the bolt surface that is in contact with the anchoring resin 32 (grout) so that when the bolt is loaded, it places the resin 32 in confined compression. This is achieved by swaging the tube 16 (or bolt) so as to form a truncated cone or by making orthogonal crimps in the tube 16. The object is to deform the bolt so that as it is loaded and moves axially, the bolt slips on the resin 32 placing the resin 32 in confined compression. Figures 15a and 15b and 16a and 16b show two bolt embodiments (single embodiment with two different end closures, figures 17a and 17b show a swaged cone pattern with a cross end, and figures 18a and 18b show a swaged straight pattern with a cross end) that will accomplish confined compression. These figures 15a-18b show hollow bolts ; however, the same concept can be achieved with solid bolts.

The crimping method on hollow bolts is the most economically practical, as it requires the least force to accomplish the required amount of deformation 30.

The bolt surface distortions should be made in such a way that axial tension on the bolt head will result in axial movement between the bolt and the grout 32 before axial movement between the grout 32 and the bore hole 12 in the

area of the distortions. If axial movement occurs first between the bore hole 12 wall and resin 32 and not between the bolt and resin 32, the resin 32 will not be subjected to confined compression and full strength will not be achieved.

Figure 15a shows a tube 16 with orthogonal crimps with a paddle end (figure 15b) at the first end 20 of the tube 16, and a flange 24 in proximity to the second end 22 of the tube 16. The spreading from the orthogonal crimp does not exceed the maximum bore hole 12 diameter. The crimp spacing is about 2 inches, and can be closer than that. The first end 20 of the tube 16 is crimped and sheared to form a single paddle end at the center of the bolt. The diameter of the paddle after crimping does not exceed the maximum bore hole 12 diameter.

The deformations 30 formed from crimping preferably only appear in the portion of the tube 16 where grout 32 is present, although they could extend the length of the tube 16. If some type of an element, such as a J-hook 48, as shown in figure 13, or an anchor bolt 50, as shown in figure 14, is positioned inside the tube 16, then the tube 16 only has deformations 30 in its upper portion so that in the lower portion of the tube 16 there is a constant inside diameter for the element to better anchor to.

When an axial tension is placed on the bolt shown in figure 15a after the bolt has anchored to the rock about the bore hole 12 with grout 32, the grout 32 between the bolt surface that tapers or angles inwards is placed in confined

compression. This can be understood by the fact that the surface of the bolt that is tapering or angling inwards towards the axis of the tube 16, as it is pulled down from the axial tension, presses against the resin 32 under it.

The resin 32, which has hardened, essentially has nowhere to go, thus experiencing compression which receives some of the load forces and better holds the bolt against the load, similar to a vice, with the greater the load, the greater the vice holding force. This can be better understood by comparing it to a bolt without any deformations 30. In such an instance, as the load increases on a bolt having a constant diameter tube 16, there is no portion of grout 32 that is under any part of the bolt. The only forces present to hold the bolt to the bore hole 12 are the adhesive forces created by the grout 32 solidifying and binding to the rock of the bore hole 12 and the tube 16 surface of the bolt.

Once the load forces are great enough, the adhesive bonds start to disintegrate, with the bolt ultimately separating from the bore hole 12. With the advantage of there being resin 32 under the inward angled portion of the deformations 30 of the tube 16, this resin 32 serves as a ledge or handle that the inward angled portion of the bolt better holds against the load. The portion of the resin 32 relative to the tube 16 shown in figure 15a that is in confined compression can be seen in figure 7.

Figure 16a shows a tube 16 with orthogonal crimps with a cross end at the first end 20 (figure 16b), and a flange 24 in proximity to the second end 22. The cross end is formed by being crimped and sheared to form a cross paddle

end at the center of the tube 16. The deformations 30 formed in the tube 16 are like those described above in regard to figure 15a. The portion of the resin 32 relative to the tube 16 shown in figure 16a that is in confined compression can be seen in figure 7.

Figure 18a shows a tube 16 with a swaged cone pattern with a cross end at the first end 20 (figure 18b), and a flange 24 in proximity to the second end 22. The portion of the resin 32 relative to the tube 16 shown in figure 17a that is a confined compression can be seen in figure 6.

Figure 17a shows a tube 16 with a swaged straight pattern with a cross end at the first end 20 (figure 17b), and a flange 24 in proximity to the second end 22. The portion of the resin 32 relative to the tube 16 shown in figure 18a that is in confined compression can be seen in figure 8.

The deformations 30 necessary to achieve superior holding power must be made such that axial tension on the bolt flange 24 results in axial movement between the tube 16 and the resin 32 and result in confined compression of the resin 32 between the bore hole and tube 16 surface. The deformations 30 are made so that they form wedges 34 that compress the resin 32 and place the tube 16 in radial/hoop compression. The tube 16 surface must be relatively smooth so it slips in the resin 32 and provides confined compression of the resin 32. In other words, the resin 32 should not

adhere to the tube 16, the tube 16 should slip slightly through the resin 32. Once it starts to slip, it acts like a"Chinese handcuff", the harder you pull, the greater the anchorage strength.

The deformations 30 should be made in the tube 16 so that the angle of the deformation 30 made relative to the bolt axis is less than 45 degrees and preferably less than 10 degrees, as shown in figures 6,7 and 8. This assures that the resin 32 will be in confined compression instead of shearing. The depth of the deformation 30 should be in the range of. 010 inches to. 300 inches. This type of deformations 30 is desirable in solid bolts also.

The deformation 30 pattern on the first end 20 of the tube 16 is cold formed using a 50 ton adjustable stroke, high speed hydraulic press. Upon actuating the ram, two containment dies are closed together simultaneously. When closed these two matching die halves contain the OD of the tubing while approximately 40 tons of force is used to form the deformation 30 pattern, as shown in figure 22. The containment die is a circumferential die with a bore diameter of 1.300". The deformation 30 pattern is created by the continuing stroke of the press which closes two duplicate forming dies onto the tubing, 180 degrees apart. The forming dies are made up of three 1-1/2"diameter circular pins equally spaced at 4"center-to-center. These pins indent/deformation 30 the tube 16 with a 3/16"deep oval pattern. These forming dies compress the tubing to form a similar three deformation 30 pattern on opposite sides of the

tube 16. The press then cycles back on top, opens the dies and the tube 16 is removed from the die set with the completed deformation 30 pattern in place.

The bead or flange 24 on the second end 22 of the bolt is hot formed using an induction heating process and a hydraulic forging machine. Approximately 1-3/4"of the tube 16 end is inserted into an induction heating coil to heat the tube 16 end to a nominal temperature of 1525 degrees Fahrenheit. The tube 16 is then placed into the hydraulic forging machine which forces the heated tube 16 end into a forming die with a resultant force of approximately 15, 000 pounds. This axial movement of the tube 16 into the forming die causes the midpoint of the heated area to bulge/deform outwards and form the beaded end, as shown in figure 23. The contours and dimensions of the beaded end are controlled by the following; steel tubing properties, the length of stroke of the hydraulic forging machine, the length of the heat affected zone and the level of heat induced into the tubing end. After forming the beaded end, the tube 16 is removed from the forging machine and is immediately submersed into a cooling tank filled with water to quench the tube 16 and establish a microstructure which gives the end ductility for resistance to failure. Additional information regarding a tube bolt can be found in U. S. patent application serial number 10/368,842 titled"Tubular Mining Bolt and Method", incorporated by reference herein.

Although the invention has been described in detail in the foregoing embodiments for the purpose of illustration,

it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be described by the following claims.