Sub-assembly, rock drilling rig, and method of absorbing vibrations in drilling

Patent metadata

Field	Value
Publication number	US-12595707-B2
Application number	US-202218714723-A
Country	US
Kind code	B2
Filing date	Dec 2, 2022
Priority date	Dec 3, 2021
Publication date	Apr 7, 2026
Grant date	Apr 7, 2026

Abstract

A sub-assembly, rock drilling rig and method of absorbing vibrations in rotary and DTH drilling. The sub-assembly is for transmitting torque and axial forces between a rotating head and a drilling tool. There is an axial floating arrangement for providing an allowed limited axial relative movement between coupling elements of the sub-assembly. The arrangement comprises several axial drive pins for transmitting the torque. First ends of the drive pins are mounted immovably and second ends are mounted with clearances, whereby the drive pins can bend under torsional shocks. Thus, the drive pins serve as torsional dampening elements.

First claim

I claim:

1 . A sub-assembly for a rock drilling unit, wherein the sub-assembly is configured to transmit torque and axial forces between a rotating head and a drilling tool, the sub-assembly comprising:
a first coupling element located at a first end of the sub-assembly for coupling the sub-assembly to the rotating head, wherein the first coupling element includes a first cover element provided with a protruding adapter pin and a second cover element located at an axial distance from the first cover element, wherein a housing element having a cylinder-like configuration is arranged between the first cover element and the second cover element for providing a floating space for the axial floating arrangement, and; a second coupling element located at an opposite, second end of the sub-assembly for coupling the sub-assembly to the drilling tool; an axial floating arrangement for providing an allowed limited axial relative movement between the first coupling element and the second coupling element, the axial floating arrangement including a plurality of axial drive pins for transmitting the torque; at least one axial fluid passageway passing centrally through the axial floating arrangement; an axial dampening arrangement having at least one first end cushion element and at least one second end cushion element for dampening axial shocks at extreme axial positions of the axial floating arrangement; and a torsional dampening arrangement for absorbing torsional shocks, wherein the plurality of axial drive pins include first ends mounted immovably and second ends mounted with clearances, whereby the plurality of axial drive pins are configured to be bent in relation to the first ends under torsional shocks and the plurality of axial drive pins serve as torsional dampening elements of the torsional dampening arrangement, wherein the first cover element is provided with a plurality of first blind openings arranged for receiving the first ends of the plurality of axial drive pins, and the second cover element is provided with a plurality of second blind openings arranged for receiving the second ends of the plurality of axial drive pins, whereby the plurality of axial drive pins are mounted between the first and second blind openings, the first blind openings of the first cover element and the first ends of the plurality of axial drive pins having tight fit connections, whereas the second blind openings of the second cover element and the second ends of the plurality of axial drive pins have clearance fit connections.

2 . The sub-assembly as claimed in claim 1 , wherein the plurality of axial drive pins serve as metallic spring elements.

3 . The sub-assembly as claimed in claim 1 , wherein the plurality of axial drive pins are made of spring steel.

4 . The sub-assembly as claimed in claim 1 , wherein the torque is configured to be transmitted between the plurality of axial drive pins and the second coupling element directly by means of the contact surfaces.

5 . The sub-assembly as claimed in claim 1 , wherein a number of the plurality of axial drive pins is 8-12, the axial pins being spaced evenly around the central fluid passageway.

6 . The sub-assembly as claimed in claim 1 , wherein the second end portions are provided with cushion rings surrounding the plurality of axial drive pins for assisting dampening.

7 . The sub-assembly as claimed in claim 1 , wherein the first end cushion element is a ring-shaped top pad and the second end cushion element is a ring-shaped bottom pad, and wherein the top and bottom ring-shaped pads are made of a resilient cushion material.

8 . The sub-assembly as claimed in claim 1 , wherein the second blind openings of the second cover element are provided with cushion space portions provided with cushion rings made of a resilient material.

9 . The sub-assembly as claimed in claim 8 , wherein the resilient material is polyurethane.

10 . The sub-assembly as claimed in claim 1 , wherein a magnitude of the clearances is 1-3 mm.

11 . A rock drilling rig for drilling drill holes to a rock surface, the rock drilling rig comprising:
a movable carrier; at least one drilling mast; a drilling unit including a feed device for moving the drilling unit on the drilling mast in a drilling direction and a return direction, and a rotating head for rotating a drilling tool around its longitudinal axis; and a sub-assembly as claimed in claim 1 , the sub-assembly being coupled between the rotating head and the drilling tool for transmitting axial forces and torque between the rotating head and the drilling tool, and wherein the sub-assembly is configured to allow axial floating between the rotating head and the drilling tool and to absorb axial and torsional shocks.

12 . A method of absorbing vibrations in rotary drilling, the method comprising:
rotating a drilling tool around its longitudinal axis by means of a rotating device; providing a sub-assembly as claimed in claim 1 between the rotating device and the drilling tool for allowing axial floating movement between the rotating device and the drilling tool and for transmitting axial forces and torque; transmitting the torque by means of a plurality of axial drive pins of the sub-assembly; absorbing axial shocks by means of an axial dampening arrangement of the sub-assembly comprising axial cushion elements; absorbing torsional shocks by means of a torsional dampening arrangement of the sub-assembly; implementing the plurality of axial drive pins as elements of the torsional dampening arrangement; providing the plurality of axial drive pins cantilever type configuration by mounting their first ends immovably and allowing their opposite second ends to move in transverse direction when torsional shocks are subjected to the sub-assembly; and and allowing the plurality of axial drive pins to bend when subjected to the torsional shocks and absorbing torsional vibrations by material properties of the plurality of axial drive pins.

13 . The method as claimed in claim 12 , further comprising providing the mountings of the second ends of the plurality of axial drive pins with clearances.

14 . The method as claimed in claim 12 , further comprising providing the mountings of the second end portions of the plurality of axial drive pins with dedicated dampening rings, and supporting the second ends of any axial drive pins having loose mountings with the dampening rings and absorbing vibrations caused by the movements of the free second ends.

15 . The sub-assembly as claimed in claim 1 , wherein the second coupling element includes an adapter housing arranged for receiving a coupling end of the drilling tool and protruding into an opposite direction relative to the adapter pin, and a stem, which is arranged inside the housing element and arranged to slide axially inside the floating space, and wherein the stem includes a plurality through openings at the plurality of axial drive pins, whereby the plurality of axial drive pins penetrate axially through the stem.

16 . The sub-assembly as claimed in claim 1 , wherein the first end cushion element is a ring-shaped top pad, the ring-shaped top pad including a central opening for the fluid passageway and a plurality of radial openings for the plurality of axial drive pins located inside the floating space at a side of the first coupling end, and wherein the second end cushion element is a ring-shaped bottom pad, the ring-shaped bottom pad including a central opening for the stem of the second coupling end and a plurality of radial openings for the plurality of axial drive pin

Assignees

• Sandvik Mining And Construction Tools Ab

Inventors

• Chavan Vitthal

Classifications

• E21B17/076 Primary

  between rod or pipe and drill bit · CPC title

• F16D3/68

  the elements being made of rubber or similar material · CPC title

• F16D3/64

  comprising elastic elements arranged between substantially-radial walls of both coupling parts · CPC title

• E21B17/073 Primary

  with axial rotation · CPC title