US 5,259,703 A · Mine roof bolt

Abstract

A passive-type mine roof bolt is constructed of multi strand steel cable. The bolt head is constructed of a hexagonal- or other drive-headed collar having an internally tapered funnel-shaped bore therethrough, and a tapered plug having a frusto-conical outer surface that engages the funnel-shaped inner surface of the drive collar. The tapered plug has an internal bore essentially concentric with the outer frusto-conical surface, and is adapted to fit over the steel cable, the hexagonal head drive collar fitting over the tapered plug such that pressing the tapered plug and steel cable into the inner funnel-shaped bore of the hexagonal-head drive collar causes serrations on the internal bore of the tapered plug to be urged down against, and bite into, the steel cable, resulting in a rigid hexagonal head for the cable bolt. The tapered plug is in actuality, a pair of essentially identical diametrically opposed semi-frusto-conical tapered sections that more easily compress together to bite into the multi-strand steel cable. A number of alternative embodiments enhance the bolt's retention strength in the bore hole to aid in stabilizing the rock formation.

Claims15

Dependent claims

A mine roof bolt comprising:

(a) a length of multi-strand cable defining a bolt shank;
(b) a tapered plug comprising a body portion having an internal bore and a frusto-conical outer surface essentially concentric with said internal bore, said tapered plug being mounted about an end of said cable at said internal bore;
(c) an internally tapered drive collar having a frusto-conical inner surface that engages said frusto-conical outer surface of said tapered plug, and having an outer surface defining a drive head that accepts a driving mechanism for rotating and linearly translating said bolt, wherein said tapered plug is mounted on an end of said cable, and said drive collar is pressed down upon said tapered plug, forcing said tapered plug against said cable, such that said drive collar, said tapered plug, and said cable, when fitted tightly together, define said mine roof bolt;
and
(d) a sleeve attached to said cable for preventing said cable from slipping relative to resin adhesive material within a bore hole, said sleeve having radially outwardly projecting fins oriented axially relative to said sleeve for centering said sleeve and said cable within the bore hole and for puncturing resin adhesive cartridges.

2 more elements

Dependencies are inferred from the claim text.

Mine roof bolt

Life of this patent

Mine roof bolt

Life of this patent

Abstract

Claims15