US 2726569 A
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Description (OCR text may contain errors)
Dec. 13, 1955 w. R. PENMAN WEDGE BOLT WITH SLOTTED END OF ELLIPTICAL CROSS-SECTION Filed Oct. 25, 1951 INVENTOR 9 h/zlter IZ. Penlluuv.
BY 2f@ United States Patent O WEDGE BOLT WITH SLOTTED END F ELLIPTICAL CRSS-SECTION Walter R. Penman, Lebanon, Pa., assigner to Bethlehem Steel Company, a corporation of Pennsylvania Application October 25, 1951, Serial No. 253,128
2 Claims. (Cl. 852) My invention relates to improvements in wedge bolts with slotted ends of elliptical cross-section and accessories.
By means of proper roof bolting, it is possible to eliminate at least a considerable part of the risk of sags and falls of overlying strata of rock and coal otherwise inherent in ordinary mining operations.
One object of this invention, therefore, is to provide a mine roof rod which will develop maximum grip and holding strength when in place under load.
Another object is a roof rod which will resist rotation while a nut is being threaded thereon.
Still other objects, purposes and advantages of the invention will appear hereinafter in the specification and drawings and in the appended claims.
In the annexed sheet of drawings:
Fig. 1 is a vertical cross-section of a mine entry, illustrating one application of my invention with a continuous roof support;
Fig. 2 is a broken side elevation of a mine roof rod, showing the lower end threaded to engage a nut and the upper end corrugated and slotted to receive an expansion wedge;
Fig. 3 is a top plan view of the mine roof rod of Fig. 2, and showing the generally elliptical form of the upper end of the rod;
Fig. 4 is a side detail view of the upper end of the rod, rotated 90 from the side shown in Fig. 2;
Fig. 5 is a horizontal transverse section of an ordinary round rod having a smooth outer surface on the upper end, showing the limited bearing area of a split round rod against the periphery of the round hole within which it is expanded by the wedge;
Fig. 6 is a transverse horizontal section of the expanded elliptical upper end of a rod having a limited number of rounded longitudinal corrugations, four on each side being shown, illustrating the enlarged area of peripheral contact with the same hole;
Fig. 7 is a transverse horizontal section of the unexpanded elliptical upper end of a rod having a larger number (shown as seven) of sharp-toothed longitudinal corrugations;
Fig. 8 is a transverse horizontal section of the upper end of the rod shown in Fig. 3; and
Fig. 9 is a transverse horizontal section of a rod having a smooth elliptical outer surface on its slotted upper end.
Referring more particularly to Fig. 1 of the drawings, the reference numeral 1 indicates a mine entry or other passageway through a coal vein 2 forming side walls or pillars 3 and having overlying strata 4 of rock, slate and the like which form a roof 5 for the passageway. Rails 6 on rail ties 7 are provided on the oor 8 for the movement of mine cars or machines in understood manner. Steel roof ties 9 or the like supply beam ICC strength and reinforcement to the mine roof 5, against which they are held by nuts 10 bearing against flat washers 11 or angle washers 12, said nuts 10 being threaded onto the lower ends 13 of round rods 14 rmly anchored in holes 21 somewhat larger than said lower rod ends 1?: drilled in the overlying strata.
In Fig. l a pair of rods 14 are shown as driven vertically upward through suitable holes in the roof tie 9, with two other rods extending divergingly outward and upward through similar holes at each end of the roof tie 9 into the rock above the pillars 3. Other arrangements or combinations of rods with other members Y are obviously possible, however.
The lower ends 13 of the rods 14 are externally threaded as at 15 to receive the nuts 10. The upper ends 16 of the rods are substantially elliptical in crosssection, with their hole-engaging outer surfaces having a radius of curvature substantially equal to or greater than the radius of the hole, and are longitudinally slotted as at 17 through their major axes. Said outer surfaces may be provided with longitudinal corrugations, either numerous and sharp-edged as at 18 (Fig. 7) or fewer and more rounded as at 19 (Fig. 8), o1' even without corrugations, asat 20 (Fig. 9), the last-mentioned form tending perhaps to be slightly less resistant to applied torque than the others. Comparison of Figs. 5 and 6 will illustrate the increase in bearing area against the hole made possible by an expanded rod surface which is elliptical instead of round, with rods of equal weight.
To expand the slotted upper ends 16 of the rods 14 against the peripheries of the holes 21, any of conventional flat-pointed wedge may be satisfactorily employed.
Although I have thus described my invention in considerable detail, I do not wish to be limited narrowly to the exact and specific particulars disclosed above, but I may also use such modications, substitutions, or equivalents as are included within the scope and spirit of the invention or pointed out in the appended claims.
l. A mine roof rod, comprising a rod having an externally threaded portion at one end and an opposite end portion of substantially elliptical crossasection, said substantially elliptical portion being longitudinally slotted through its major axis and adapted to be expanded in a circular hole in the mine roof, the radius of curvature of the hole-engaging surface of said elliptical slotted end portion being at least equal to the radius of the hole,
2. A mine roof rod, comprising a rod having an externally threaded portion at one end and an opposite end portion of substantially elliptical cross-section, said substantially elliptical portion being longitudinally slotted through its major axis and adapted to be expanded in a circular hole in the mine roof; the radius of curvature of the hole-engaging surface of said elliptical slotted end portion being at least equal to the radius of the hole, said hole-engaging surface being further provided with a plurality of external corrugations; whereby said rod is characterized by great holding power and resistance to rotation when expanded in a circular hole.
References Cited in the le of this patent UNITED STATES PATENTS 419,018 King et al Jan. 7, 1890 660,566 Gage Oct. 30, 1900 710,216 Schmidt Sept. 30, 1902 1,229,287 Kennedy June 12, 1917 1,251,566 Pigott Jan. 1, 1918 1,349,998 Aylward Aug. 17, 1920