Mine roof bolt anchor
OwnerClaude Whiteinventor
Life of this patent
Estimating the term…
Abstract
An anchor for a mine roof bolt incorporates a single large rib at the top of a segmented shell. This single large rib is forced into the wall of the bore hole by the downward movement of an associated threaded camming nut during the first few revolutions of the roof bolt. The remainder of the outer surface is generally smooth or unserrated and provides a large bearing surface which is urged against the bore hole wall upon further rotation of the bolt. The camming nut has a specific shape flaring substantially near its upper end such that a relative large area of the bore hole wall below the rib is forced into compression. When fully engaged, the camming nut compresses a tightening washer of a metal alloy softer that the camming nut or the shell. The washer is forced into the threads of the nut thereby preventing loosening of the bolt.
Claims14
A mine roof bolt anchor, insertable in a pre-drilled hole in a mine roof, for expansion within said hole by rotation of an associated mine roof bolt, comprising, in combination:
- a. a shell circumscribing said mine roof bolt and having a plurality of segments extending longitudinally of said bolt, said segments having a radially inward face defining a camming surface and terminating in a radially outwardly protruding rib at an upper end thereof, said shell including an internal flange forming a lower reduced diameter portion;
- b. a camming nut threadedly engaged on said mine roof bolt and having a radially outwardly flaring surface for engagement with said camming surface, said flaring surface having an abrupt variation in its slope proximal an upper end thereof;
- c. a compression washer positioned within said shell on said flange for securing said mine roof bolt therethrough;
- and,
- d. means engagable with a wall of said hole upon rotation of said mine roof bolt for arresting the rotation of said shell relative thereto, such that further rotation of said mine roof bolt urges said camming nut linearly along the axis of said mine roof bolt displacing said segments radially such that said rib is forced into said wall and said segments are urged against said wall over a large surface area of said shell to compress said wall in the region beneath said rib.
An anchor for use with a mine roof bolt to be inserted into a pre-drilled hole in a mine roof, comprising in combination:
- a. a segmented shell having a substantially cylindrical shape conforming to the outer diameter of said mine roof bolt for enclosing a portion thereof therein, said segment shell having a lower annulus and a plurality of upwardly oriented segments, each segment of said plurality of segments terminating at an outwardly extending rib and having an inner camming face formed thereon;
- b. a camming nut threadedly engaged on said mine roof bolt superjacent said segmented shell in cooperative relation therewith such that rotation of said bolt relative to said nut moves said nut vertically, said nut having a flared outer surface engagable with said camming face of each segment;
- c. a compression washer for engagement between said camming nut and said shell adjacent said annulas;
- and,
- d. means for arresting rotational movement of said shell within said pre-drilled hole.
A mine roof bolt anchor to be inserted into a pre-drilled hole in a solid surface, comprising in combination:
- a. a segmented metallic shell having a shape conforming to the outer diameter of said bolt for enclosing a portion thereof therein, said segmented shell having a lower annulus and a plurality of upwardly oriented segments, each segment having an outer surface having a single annular protruding rib for engaging said hole and an inner camming surface;
- b. a metallic camming nut threadedly engaged on said anchor bolt superjacent said segmented shell in cooperative relation therewith such that rotation of said bolt relative to said nut moves said nut vertically, said nut having a flared outer surface engagable with said camming face of each segment;
- c. a compression washer for engagement between said camming nut and said shell, said compression washer being comprised of an alloy of metal softer than said metallic shell and metallic camming nut, allowing it to distort and conform to the interstitial space between said shell, nut and bolt when said bolt is tightened;
- and,
- d. means for arresting rotational movement of said shell within said pre-drilled hole.
Dependencies are inferred from the claim text.