Friction bolt

Patent metadata

Field	Value
Publication number	US-9797249-B2
Application number	US-201515317883-A
Country	US
Kind code	B2
Filing date	Jun 8, 2015
Priority date	Jun 13, 2014
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

A friction bolt for frictionally engaging the internal surface of a bore includes a circular tube, which is split longitudinally, and which has a leading end and trailing end. An expander mechanism is disposed within the tube towards the leading end. An elongate bar/cable is disposed within the tube and extends between the expander mechanism at one end and an anchor arrangement at the other end. The bar/cable extends through a ring attached to the trailing end into connection with the anchor arrangement. A restrainer member is disposed within the tube adjacent the ring and extends at least partially about and in engagement with the bar/cable. The tube has a weakened region adjacent the ring and the restrainer member extends longitudinally within the tube past the weakened region. The restrainer member includes a projection that projects through the longitudinal split of the tube for engagement with the bore.

First claim

The invention claimed is:

1. A friction bolt, for frictionally engaging the internal surface of a bore drilled into a rock strata, the friction bolt comprising:
an elongate, generally circular tube having a longitudinal split for radial expansion of the tube, the tube having a leading end and a trailing end;
an expander mechanism disposed within the tube in a region of the leading end for applying a load to expand at least one section of the tube radially;
an elongate bar or cable having opposed end disposed longitudinally within the tube, a first end of the bar or cable being connected with the expander mechanism and a second end of the bar or cable being connected to an anchor arrangement positioned at the trailing end of the tube;
a ring welded to the trailing end of the tube, the bar or cable extending through the ring beyond the trailing end of the tube into connection with the anchor arrangement; and
a restrainer member disposed within the tube adjacent the ring, the restrainer member extending at least partly about the bar or cable and being in engagement with the bar or cable, the tube having a weakened region adjacent the ring and the restrainer member extending longitudinally within the tube past the weakened region in the direction of the leading end of the tube, the restrainer member including a projection that projects through the longitudinal split of the tube for engagement with a facing wall of a bore that the rock bolt is inserted into.

2. The friction bolt according to claim 1 , wherein the projection extends longitudinally of the longitudinal split.

3. The friction bolt according to claim 1 , wherein the projection has a profile that includes ribs or barbs extending laterally across the projection.

4. The friction bolt according claim 1 , wherein the restrainer member extends past the weakened region by an amount of between 40 and 300 mm.

5. The friction bolt according to claim 1 , wherein a length of the restrainer member is from about 50 mm to about 300 mm.

6. The friction bolt according to claim 5 , wherein a length of the restrainer member is about 150 mm.

7. The friction bolt according to claim 1 , wherein the restrainer member is tubular and has a central bore to receive the bar or cable.

8. The friction bolt according to claim 7 , wherein the restrainer member is cylindrical.

9. The friction bolt according to claim 7 , wherein the restrainer member has a diameter that is close to or equal to an inside diameter of the tube, prior to the tube being inserted into the bore.

10. The friction bolt according to claim 1 , wherein the restrainer member is in engagement with an inside surface of the tube past the weakened region to create sufficient drag between the restrainer member and the inside surface of the tube past the weakened region, which upon failure of the tube in the weakened region and failure of the bar or cable form a leading bar or cable part and a trailing bar or cable part, the restrainer member restraining the trailing bar or cable part against ejection from the rock bolt.

11. The friction bolt according to claim 1 , wherein the restrainer member is tubular and includes a central bore to receive the bar or cable and a slot or slit extending longitudinally through a length of the restrainer member between the outside surface of the part and the central bore.

12. The friction bolt according to claim 1 , wherein the restrainer member is formed in two separate parts.

13. The friction bolt according to claim 12 , wherein the two parts form an engagement when installed in the tube, the engagement occurring along inclined or angled faces of the two parts on either side of the bar or cable.

14. The friction bolt according to claim 13 , wherein the engagement forms a wedge engagement.

15. The friction bolt according to claim 12 , wherein one or both of the first and second parts include a lip or finger at a trailing end thereof that is positioned on a side of the ring of the rock bolt opposite the remainder of the restrainer member when the restrainer member is fully installed.

16. The friction bolt according to claim 12 , wherein one or both of the first and second parts include an annular groove or channel at a trailing end thereof within which the ring of the rock bolt can seat.

17. The friction bolt according to claim 1 , wherein the tube is deformed inwardly to form an indent that pushes into a side wall of the restrainer member.

18. The friction bolt according to claim 1 , wherein the bar includes surface ribs or threads along a length of the bar which are removed in the section of the bar about which the restrainer member is installed.

19. The friction bolt according to claim 18 , wherein the ribs or threads of the bar that are adjacent the leading end of the restrainer member form an abutment against which the leading end of the restrainer member abuts.

20. The friction bolt according to claim 1 , wherein the restrainer member is formed in two parts, a first part being a body and a second part the projection.

21. The friction bolt according to claim 20 , wherein the body and the projection include cooperating connectors that connect together.

22. The friction bolt according to claim 21 , wherein the body includes an opening or openings to accept a pin or pins or the like formed to extend from an underside of the projection.

23. The friction bolt according to claim 22 , wherein the pins are formed to provide a snap connection with the body.

24. A restrainer member for use with a friction bolt that is used for frictionally engaging an internal surface of a bore drilled into a rock strata, the friction bolt comprising;
an elongate, generally circular tube including a longitudinal split for radial expansion, the tube having a leading end and a trailing end;
an expander mechanism disposed within the tube in a region of the leading end for applying a load to expand at least a section of the tube radially;
an elongate bar or cable having opposed ends disposed longitudinally within the tube, a first end of the bar or cable being connected with the expander mechanism and a second and opposite end of the bar or cable being connected with an anchor arrangement positioned at the trailing end of the tube;
a ring welded to the trailing end of the tube, the bar or cable extending through the ring beyond the trailing end of the tube into connection with the anchor arrangement, the tube having a weakened region adjacent the ring, the restrainer member being arranged for insertion into the tube adjacent the ring, to extend longitudinally within the tube past the weakened region in the direction of the leading end of the tube and to extend about the bar or cable and to be in engagement with the bar or cable; and
a projection projecting through the longitudinal split of the tube for engagement with a facing wall of the bore that the friction bolt is inserted into.

Assignees

• Sandvik Intellectual Property
• Sandvik Intellectual Property

Inventors

• Rataj Mieczyslaw
• Czekaj Justyna
• Darlington Bradley

Classifications

• E21D21/0033 Primary

  having a jacket or outer tube · CPC title

• E21D21/004 Primary

  Bolts held in the borehole by friction all along their length, without additional fixing means · CPC title