US 4,784,530 A · Roof bolt apparatus

Abstract

The apparatus for anchoring a bolt includes an elongated bolt with a threaded portion located at a preselected position along the length of the bolt and spaced from the end portions of the bolt. An expansion shell assembly is positioned on the bolt with the camming plug portion threadedly secured to the bolt threaded portion so that the expansion shell assembly is positioned in spaced relation to the ends of the bolt. In one embodiment, the threaded portion of the bolt includes a threaded sleeve suitably secured to the bolt at a location between the end portions of the bolt. In another embodiment, the bolt has a threaded portion located between the unthreaded end portions and a C-shaped stop member is secured on the lower portion of the threads. A camming plug is formed in longitudinal halves that are positioned around the threaded portion of the bolt and held in place by the fingers of the expansion shell assembly. A method is also disclosed where the threaded portion of the bolt is located at a preselected location between the ends of the bolt and the expansion assembly is threadedly engaged to the threaded portion of the bolt at the preselected location and is expanded to engage the bore hole at that location. A chemical bond may also be employed to engage another portion of the bolt to the bore hole.

Drawings

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Drawings

Claims15

Dependent claims

An expansion shell assembly comprising,

a sleeve having a body portion with an upper end portion and a lower end portion and an axial bore extending through said body portion,
said body portion having an inner surface and an outer threaded surface,
a camming plug having a threaded axial bore and an outer surface, said camming plug threadedly engaged to said sleeve at a preselected location on said sleeve outer threaded surface,
an expandable shell having a plurality of longitudinally extending fingers spaced from one another by longitudinal slots,
said fingers each having an inner surface and an outer surface, each finger inner surface abutting said camming plug outer surface,
said camming plug being movable on said sleeve outer threaded surface relative to said expandable shell to exert an outward force upon said inner surfaces of said fingers to expand said fingers outwardly from said sleeve, and
said expansion shell assembly arranged to be secured to a roof bolt at a preselected location along the length of said roof bolt with the inner surface of the sleeve secured to the outer surface of said bolt.

4 more elements

Apparatus for anchoring a bolt in a bore hole of a rock formation comprising,

an elongated bolt having unthreaded portions extending between the ends thereof,
a sleeve having a body portion with an inner surface and an outer threaded surface,
said sleeve body portion having an upper end portion and a lower end portion with an axial bore through said body portion,
said sleeve axially positioned on said bolt unthreaded portion at a preselected location, said sleeve being secured to said bolt outersurface,
a camming plug having a threaded axial bore and an outer surface, said camming plug threadedly engaged to said sleeve at a preselected location on said sleeve outer threaded surface,
an expandable shell having a plurality of longitudinally extending fingers spaced from each other by longitudinal slots,
said fingers each having an inner surface and an outer surface,
said expandable shell positioned on said sleeve with said finger inner surface abutting said camming plug outer surface, and
said camming plug being movable on said sleeve outer threaded surface relative to said expandable shell upon rotation of said bolt to expand said fingers outwardly from said sleeve.

6 more elements

Dependencies are inferred from the claim text.

Description7,019 words

Summary3,034 words

#1. Field of the Invention

#This invention relates to a method and apparatus for anchoring a roof bolt in a bore hole of a rock formation and more particularly to an expansion shell assembly that is capable of being positioned at a preselected location along the length of a roof bolt to control the point of mechanically anchoring the roof bolt in the bore hole.

#2. Description of the Prior Art

Brief description of the drawings9 figures

#FIG. 1 is an enlarged, fragmentary, isometric view, partially in section, of roof bolt apparatus having an expansion shell assembly including an externally threaded sleeve secured to the bolt with an expansion shell and camming plug engaging the sleeve.

#FIG. 2 is a sectional view of the roof bolt apparatus similar to that shown in FIG. 1 illustrating the externally threaded sleeve adhesively secured in a fixed axial position on the bolt with a camming plug engaging the threads of the sleeve and an expandable shell member surrounding the camming plug. The sleeve illustrated includes a lower portion that is not threaded.

#FIG. 3 is a view similar to FIG. 2, illustrating the shell member expanded into engagement with the rock formation surrounding the bore hole.

Detailed description3,640 words

#Referring to the drawings and particularly to FIGS. 1, 2 and 6-9, there is illustrated roof bolt apparatus generally designated by the numeral 10 for insertion in a bore hole 12 of a rock formation, shown in detail in FIGS. 6-9, to support the rock formation 14. The rock formation 14 ca example, a mine roof that overlies a mine passageway or shaft, a subway tunnel, or other similar subterranean structure.

#The roof bolt apparatus 10 includes, in one embodiment, as shown in FIGS. 1-3, an elongated bolt 16 having a smooth outer cylindrical surface 18. The bolt 16 has a preselected length, for example 42 inches to 6 feet or longer. In another embodiment of the roof bolt apparatus 10, as shown in FIGS. 4 and 5, a reinforcing rod 20 is utilized and includes an outer surface 22 on which is disposed a compound helical pattern of ribs 24. The ribs 24 protrude outwardly from the rod surface 22 and extend the length of the rod 20. Throughout the specification and claims, the terms bolt and rod will be used interchangeably to refer to that portion of the bolt apparatus to which the expansion shell assembly is secured.

#An expansion shell assembly generally designated by the numeral 26 is positioned at a preselected location along the length of the bolt 16 or rod 20 and includes a sleeve 28, which is bonded to the bolt surface 18 or the rod surface 22. The sleeve 28 has an elongated body portion 30 with an upper end portion 32 and a lower end portion 34. An axial bore 36 extends through the sleeve body portion 30, thus forming a cylindrical inner surface 38 having a diameter corresponding substantially to the diameter of the bolt 16 or rod 20 permitting slidable movement of the sleeve 28 to a preselected location along the length of the bolt 16 or rod 20 before the sleeve 28 is secured thereto. The sleeve 28 has an outer threaded surface 40 that extends substantially the length of the sleeve body portion 30 from the upper end portion 32 to a position adjacent the lower end portion 34. As seen in FIG. 2, a portion of the sleeve outer surface is not threaded at the lower end portion 34 and serves as a stop 35 for a nut as later described. It should be understood other types of stops may be used, as for example, an interruption in the threads such as the peened portion 43 or an abutment means formed on the sleeve, as shown in FIG. 2.

Facts

Application

07/107,258Filed 9 Oct 1987 · continuation

Priority

31 Dec 1984

Granted

15 Nov 1988

Term ended

15 Nov 2005

Estimated · how

Pre-1995 term; greater of 17 years from grant or 20 years from filing when eligible. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification3 codes

E21D 21/008
Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection: anchoring or tensioning means
E21D 20/025
With provisions for grouting: grouting with organic components, e.g. resin
E21D
Shafts

Roof bolt apparatus

Life of this patent

Roof bolt apparatus

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims15

Description7,019 words

Drawings

Classification3 codes

Life of this patent

Description7,019 words