US 3,938,420 AGranted

Mine roof bolt anchor construction

AssigneeGottschall Tool & Die, Inc.

InventorWayne A. Draa

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Abstract

A bolt anchor construction for attaching metal plates to the roof of a mine tunnel. An expansion shell having a plurality of spaced metal fingers is telescopically mounted on a bolt. A camming plug is threadably mounted on one end of the bolt and is located within and engaged with the spaced fingers. A series of coined teeth is formed in the outer surface of each finger with the rear of the teeth forming a smooth, flat, tapered surface extending downwardly outwardly with respect to the inner surface of the fingers. The camming plug forces the fingers outwardly upon rotation of the bolt whereupon the teeth bite into the rock surrounding the drilled hole to attach the plates to the mine roof. A pair of spaced longitudinally extending bearing strips is formed on the inner surface of each finger for engagement with the camming plug, and the teeth smooth rear surfaces are located between the bearing strips and are free of projections to prevent bending with the plug.

Claims11

Dependent claims

Mine roof bolt anchor construction including:

a. a bolt having a threaded shank portion;
b. a camming plug threadably engaged with said bolt for advancement along the threaded shank portion;
c. an expansion shell mounted on the bolt;
d. the expansion shell including a plurality of metal fingers surrounding the bolt and engageable with the camming plug;
e. the fingers each having a free end and outer, inner and side surfaces;
f. a series of teeth coined in each of said fingers and projecting outwardly from the outer finger surface;
g. each finger inner surface having a pair of spaced generally planar bearing strips extending longitudinally adjacent the finger side surfaces engageable with the camming plug, and a single rectangular planar surface extending between said bearing strips;
h. the rectangular planar surface being tapered from the finger free end outwardly away from the bearing strips, and the teeth being coined from finger material displaced in forming said tapered planar surface, with the rectangular planar surface constituting a smooth back surface for the series of teeth and forming the entire area between the spaced bearing strips;
i. the majority of the teeth include major planar facets extending outwardly downwardly with respect to the outer finger surface and minor planar facets extending outwardly upwardly with respect to the outer finger surface;
j. and tooth crests being formed by the junctions of said major and minor planar facets and extending transversely with respect to the shell fingers.

7 more elements

An expansion shell for a mine roof bolt anchor construction of the type having a bolt with a threaded shank portion, in which a camming plug is threadably engaged with the bolt, in which the expansion shell is telescopically mounted on the bolt and engageable with the camming plug, and in which the shell is expanded outwardly upon advancement of the plug along the threaded shank portion within the expansion shell;

the expansion shell including:
a. a collar and a plurality of metal fingers extending from said collar;
b. the fingers each having a free end and outer, inner and side surfaces;
c. a series of teeth coined in each of said fingers and projecting outwardly from the outer finger surface;
d. each finger inner surface having a pair of spaced generally planar bearing strips extending longitudinally adjacent the finger side surfaces engageable with the camming plug, and a single rectangular planar surface extending between the bearing strips;
e. the rectangular planar surface being tapered from the free finger end outwardly away from the bearing strips and forming the entire area between the spaced bearing strips and constituting a smooth back surface of the series of teeth, with the teeth being formed from finger material displaced in forming the planar back surface;
f. certain of the teeth each includes a major planar facet extending outwardly downwardly with respect to the outer finger surface and a minor planar facet extending outwardly upwardly with respect to the outer finger surface;
g. and tooth crests being formed by the junction of said major and minor planar facets, with the metal thicknesses of certain teeth crests being equal.

5 more elements

Dependencies are inferred from the claim text.