GB2243315A

GB2243315A - Telescopic drilling rod

Info

Publication number: GB2243315A
Application number: GB9009609A
Authority: GB
Inventors: John Arthur Ledger
Original assignee: BOART
Current assignee: BOART
Priority date: 1990-04-28
Filing date: 1990-04-28
Publication date: 1991-10-30
Also published as: GB9009609D0

Abstract

The rod has a hollow sleeve (34), means (28) for mounting a drill bit at one end of the sleeve, a shaft (32) fitted within the sleeve, a hydraulic piston/cylinder unit housed within the sleeve and connecting the shaft to the sleeve so that operation of the piston/cylinder unit results in telescopic movement of the shaft and the sleeve. The unit cylinder (38) is coupled to the shaft and the piston (42) and rod (40) are coupled to the sleeve (34). A slip ring arrangement (44) provides for fluid connections to the unit from a stationary part. Relative rotation between the shaft and sleeve is prevented by axially extending external ribs on the former abutting internal axially extending lugs in the latter. <IMAGE>

Description

DRILLING ROD This invention relates to a drilling rod particularly for use in drilling holes in rock and in mining applications.

The term drilling rod includes, inter alia, longhole drilling rods and drilling augers.

Where a long hole has to be drilled in a mine, it may be impossible or impractical to use a drilling rod which is of the full length of the hole, because it may not be possible to manoeuvre such a long rod into the right position in a mine working. It is therefore known to use sectional rods such that a first rod section carrying a drill bit is drilled into the rock face, drilling is stopped and a second rod section is screwed to the back of the first rod section, and drilling is then continued. It is however undesirable to have to stop drilling for the connection of further drill rod sections, and it is an aim of the present invention to overcome this drawback.

According to the present invention, there is provided a telescopic drilling rod comprising a hollow sleeve, means for mounting a drill bit at one end of the sleeve, a shaft fitted within the sleeve, a hydraulic piston/cylinder unit housed within the sleeve and connecting the shaft to the sleeve so that operation of the piston/cylinder unit results in telescopic movement of the shaft and the sleeve, and means for preventing relative rotation between the shaft and the sleeve.

With a drilling rod of this type, the sleeve can be fully retracted over the shaft whilst the rod is being bought into position for drilling. During the course of drilling, the piston/cylinder unit can be extended so that the length of the rod is hydraulically extended to give an effective longer rod so that a hole of length greater than the length of the retracted rod can be drilled.

Drilling is accomplished by rotating the rod in a conventional manner. In order to provide the necessary hydraulic feed to the piston/cylinder unit which will be rotating with the rod, a hydraulic slip ring may surround the end of the shaft which is connected to a rotary drive, and hydraulic fluid passages may extend from the slip ring to the piston/cylinder unit within an axial bore in the shaft.

Preferably the piston rod of the piston/cylinder unit is pinned to the sleeve and the cylinder is pinned to the shaft. The piston/cylinder unit can be mounted on the axis of the rod, between the outermost end of the shaft and the outermost end of the sleeve.

The means for preventing relative rotation may comprise external axial ribs on the shaft which co-operate with internal axial projections on the sleeve. During drilling, the rotation applied to the shaft by the rotary drive will be transmitted to the sleeve through the ribs and projections. The ribs and projections preferably extend parallel to the shaft axis.

In order to support the rod, a bearing can be provided at the end of the sleeve remote from the drill bit.

The drilling rod may be an auger with a helical scroll or flight on the outer surface.

The invention will now be fully described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic drawing showing a mining machine with a drilling rod according to the invention in a mine heading; Figure 2 is a side view of a drilling rod according to the invention; Figure 3 is a sectional view of the rod of Figure 2, with the rod extended; Figure 3a is an enlarged detail part of Figure 3; and Figure 4 is a cross-section on the line IV - IV from Figure 3 Figure 1 shows a carrier chassis 10 in a mine tunnel 12.

The chassis is supporting a boom 14. A feed beam 16 is supported at the outer end of the boom 14, and by means of articulated joints at either end of the boom 14, the beam 16 can be moved to a wide range of different positions.

On the beam 16 there is a rotary drive motor 18 which drives a drilling rod 20. At the outer end of the rod 20 is a drill bit 22, and the drive 18 can be advanced along the beam 16 to bring the drill bit into contact with the rock face 24. Rotation of the drive 18 together with simultaneous advancing of the drive causes the bit to drill a hole in the rock.

This arrangement is only one example of various different arrangements which could be used to mount the drill rod 20.

By way of example, the rod could alternatively be mounted directly to the chassis of an auger boring machine.

The construction of the drill rod 20 itself is shown in more detail with reference to Figures 2, 3, 3a and 4. The drill rod shown here is in fact an auger and has an external helical winding 26 formed on its outer surface.

At the outer end of the rod there is typically a socket 28 onto which a drill bit can be fitted. At the other end of the rod there is a head 30 which will be connected to a rotary drive 18 in a manner which is already known.

The rod comprises a hollow shaft 32 and a hollow sleeve 34.

The shaft has an inner end 36 within the sleeve 34, and the cylinder 38 of a hydraulic piston/cylinder unit is connected to the end 36 of the shaft. A piston rod 40 is connected at 42 to the sleeve 34.

Figure 2 shows the rod in its fully retracted, and therefore its shortest condition. Figure 3 shows the rod in its fully extended condition, that is with the piston rod 40 extended by its maximum amount from the cylinder 38.

It will be clear that the size of the piston/cylinder unit 38,40 can be chosen to produce an extension of the rod which may be greater or lesser than that shown.

In order to allow flow of hydraulic fluid at any rotational position of the rod, a slip ring construction is provided at 44. This construction is shown in more detail in Figure 3a. An outer ring 46 which remains stationary receives hydraulic fluid from two hoses 48 and 50 (feed and return).

An annular body 54 at the end of the shaft 32 has two passages 52 (only one is shown) which communicate the external hydraulic pipes 48, 50 with respective internal hydraulic pipes 56 and 58 which constitute the feed and return conduits to the cylinder 38.

In order to transmit the rotational drive which is applied to the shaft 32 via the head 30, the external surface of the shaft is provided with ribs 60. On the internal face of the sleeve 34 there are internally projecting dogs 62, and the relative lengths of the ribs 60 and the dogs 62 is such that the two are always in contact over the full range of telescopic movement. It is normally only necessary for drive to be transmitted between the ribs 60 and the dogs 62 in one rotational direction.

In order to provide a bearing between the shaft 32 and the sleeve 34, a split bearing or bushing is fitted at 64.

This also provides a seal for closing the interior of the sleeve 34.

In use, drilling will normally be started with the rod retracted, i.e in the condition of Figure 2. In order to lengthen the drill rod, the piston/cylinder unit 38, 40 is extended. This can be accomplished with or without stopping the rotary drive and with or without stopping the forward feed of the drill rod 20.

The invention therefore provides a drill rod which can be quickly and easily extended during operation, to drill a hole which is longer or deeper the retracted length of the rod.

Claims

1. A telescopic drilling rod comprising a hollow sleeve, means for mounting a drill bit at one end of the sleeve, a shaft fitted within the sleeve, a hydraulic piston/cylinder unit housed within the sleeve and connecting the shaft to the sleeve so that operation of the piston/cylinder unit results in telescopic movement of the shaft and the sleeve, and means for preventing relative rotation between the shaft and the sleeve.

2. A drilling rod as claimed in Claim 1, wherein one end of the shaft is adapted to be connected to a rotary drive, a hydraulic slip ring surrounds said one end of the shaft, and hydraulic fluid passages extend from the slip ring to the piston/cylinder unit within an axial bore in the shaft.

3. A drilling rod as claimed in Claim 1 or Claim 2, wherein the piston rod of the piston/cylinder unit is pinned to the sleeve and the cylinder is pinned to the shaft.

4. A drilling rod as claimed in any preceding claim, wherein the piston/cylinder unit is mounted on the axis of the rod, between the outermost end of the shaft and the outermost end of the sleeve.

5. A drilling rod as claimed in any preceding claim, wherein the means for preventing relative rotation comprises external axial ribs on the shaft which co-operate with internal axial projections on the sleeve.

6. A drilling rod as claimed in Claim 5, wherein rotary drive will be transmitted to the sleeve through the ribs and projections during drilling.

7. A drilling rod as claimed in Claim 5 or Claim 6, wherein the ribs and projections extend parallel to the shaft axis.

8. A drilling rod as claimed in any preceding claim, wherein a bearing is provided at the end of the sleeve remote from the drill bit in order to support the sleeve.

9. A drilling rod as claimed in any preceding claim, in the form of an auger with a helical scroll or flight on the outer surface of the sleeve.

10. A drilling rod substantially as herein described with reference to and as shown in the accompanying drawings.