GB1603608A - Drive unit for drill rig - Google Patents

Description

(54) DRIVE UNIT FOR DRILL RIG (71) We, UNDERGROUND MINING MACHINERY LIMITED, a British com- pany, of Aycliffe Industrial Estate, Darlington, Co. Durham, England, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a drive unit for a drill rig and to a drill rig incorporating such a drive unit. The invention is concerned particularly with a drill rig that can be transported from place to place by means of a lorry or tractor-pulled trailer.

Drill rigs of this type have a mast which can be pivoted from a substantially horizontal position (this being a non-working position in which transport of the rig is facilitated) to a vertical working position. In this working position, the bottom end of the mast is positioned slightly to the rear of its carrying trailer. The trailer itself is provided with hydraulic jacks which can be braced against the ground to take up the reaction forces arising from drilling operations. A hydraulic drive unit is provided for the drill string used for drilling, the drive unit (rotary head or power swivel) being pivotally mounted on a carriage which is movable along the mast.In one method of adding further drill rods to a drill string as drilling proceeds, the pivotal mounting is necessary to enable the rotary head to pivot through an angle (of up to 90 ) to allow a drill rod to be attached. The carriage and rotary head are then traversed up the mast drawing the new rod into a vertical position where it can be coupled to the rods already in the hole.

Such a hydraulic top drive rotary head may be one of a variety of types. Thus, it may have a solid spindle or a hollow spindle and the hydraulic drive to the spindle may be either direct or via various types of gearing combinations of hydraulic motors.

Moreover, such a head is usually fitted with an air/water or air/mud swivel unit for direct circulation removal of cuttings or with a gooseneck assembly for removal of cuttings during reverse circulation drilling.

These types of rotary heads have various disadvantages. Thus, the facilities for changing the drilling speed are generally cumbersome or inflexible, requiring combinations of hydraulic motors or change of gearing, the latter necessitating dismantling and rebuilding of the basic unit which in turn requires workshop facilities. Moreover, the position of the trunnions which pivotally mount the rotary head to the carriage give rise to further problems. This is because the gooseneck assembly has to be added on top of the rotary head which means that a considerable space must be left between the pivots on the carriage and the mast, otherwise the gooseneck assembly would jam against the mast before the rotary head had pivoted far enough to permit the addition of a further drill rod.A similar problem also arises when the gooseneck assembly is not used, as the rotary head itself extends upwardly of its trunnions. In either case this results in a considerable distance between the mast and the spindle centre line which in turn means a large moment arm and hence a robust mast to cater for this force.

Moreover, this distance between the mast and the spindle centre line results in the hole being drilled being offset well beyond the end of the trailer and so limits the weight of drill string that can be handled without the entire rig toppling over (the mast in this case lying beyond the hydraulic jacks which support the trailer).

A further disadvantage of these known types of rotary head is that changing the drilling method from direct to reverse circulation normally requires changes to the rotary head assembly. The air/water/mud supply hoses, hydraulic oil supply hoses, and debris circulation hoses all require to be removed and repositioned for this changeover and this is a time-consuming operation, as these hoses are cumbersome. Also, sealing to prevent contamination of the rotary head lubricant by debris during reverse circulation drilling is normally both complex and suspect.

The present invention provides a drive unit for a drill rig, the drive unit comprising a rotary head and a gooseneck assembly, the rotary head having input drive means connectible to a motor via a gearbox, and output drive means connectible to a drill rod, a hollow spindle constituting the output drive means, wherein the gooseneck assembly is connected to the rotary head with the interposition of a seal for excluding drilling debris from the interior of the rotary head and wherein the gooseneck assembly is provided with a pair of co-axial pivot points for attaching the drive unit to a carriage movable along the mast of the drill rig, the axis of the pivot points passing through the outlet of the gooseneck assembly.

As is usual with such drive units, the gooseneck assembly is provided at the top of the rotary head. Thus, the drive unit pivot points are also provided at the top of the unit and so the problems which existed for known drive units arising from the space between the pivot points and the mast are considerably reduced. This in turn leads to reduced mast loading and reduction in the distance from the hole being drilled to the jacks used to support the drill rig.

A particular advantageous form of gooseneck assembly is one which is of T-shape, the bar of the T forming the pivot points. Preferably, the outlet of the gooseneck assembly is provided at one end of said bar, and a venturi tube is detachably mounted inside said bar adjacent the other end thereof.

Preferably, the drive unit further comprises a gearbox detachably mounted on the rotary head and in drivable engagement with the input drive means. In practice, a number of auxiliary gearboxes are provided so that the gear ratio can be changed on site by simply changing the gearbox.

Advantageously, the rotary head is formed with internal lubrication galleries fed by an independent lubricant supply.

Such an arrangement improves lubrication and so allows higher speed ranges than known drive units.

The invention also provides a drill rig comprising a wheeled support vehicle, a mast pivotably mounted on the vehicle, a carriage movable along the mast, and a drive unit pivotably attached to the carriage, the drive unit being as defined above.

Advantageously, the vehicle is provided with hydraulic support jacks. Preferably, the vehicle is a trailer.

A drill rig incorporating a drive unit constructed in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side elevation of the drill rig; Figure 2 is a side elevation, on a larger scale, of the mast and drive unit of the drill rig of Figure 1; Figure 3 is an axial cross-section of the drive unit; Figure 4 is a transverse cross-section of the drive unit; Figure 5 is a part-sectional view of part of the drive unit; and Figure 6 is a cross-section of the gooseneck assembly of the drive unit.

Referring to the drawings, Figure 1 shows a drill rig, generally designated by the reference numeral 1, securely fixed to the chassis 2 of a lorry 3 by means of a skid assembly 4. A mast 5 is pivotably attached to the skid assembly 4 and is movable by means of hydraulic rams 6 from a generally horizontal position (shown in chain-dotted line) to a vertical position (shown in full lines). The mast 5 is arranged to be in the former position when being transported and in the latter position for drilling purposes.

The mast 5 is provided with a bottom working table 7. A carriage 8 is reciprocable along the mast 5, and a drive unit, indicated generally by the reference numeral 9, is pivotably attached at 10 to the carriage. A rear jack assembly 11 is provided adjacent to the bottom working table 7 for supporting the mast 5 during drilling. The carriage 8 is moved along the mast 5 either by a winch or hydraulically using a pulley assembly 12.

The pulley assembly 12 carries wire ropes which are connected to a hydraulic cylinder (not shown) within the mast 5. These wire ropes haul the carriage up and down the mast 5 hydraulically. If the drill string is extremely heavy, then an auxiliary pulley assembly known as the Crown Block (not shown) is assembled at the top of the mast 5 and a winch (not shown) is used to lift or lower the carriage 8 by means of an additional wire rope. In this case the carriage 8 is detached from the hydraulic system associated with the pulley assembly 12. A power unit 13, a hydraulic oil tank 14 and control valves (not shown) are carried on the trailer 2 for operating the hydraulic control of the carriage 8, the hydraulic rams 6 and other hydraulic components to be described below.

The drive unit 9 (see Figure 2) is constituted by a rotary head 15, an auxiliary gearbox 16 and a gooseneck assembly 17.

The rotary head 15 (see Figures 3 and 4) has a 6 inch diameter hollow spindle 18 rotatably mounted within a housing 19 by means of two sets of tapered roller bearings 20.

The spindle 18 is driven by a worm gear 21 which engages within a hollow output shaft of the gearbox 16. A hydraulic motor 22 drives the gearbox 16. The gearbox is easily detachable from the rest of the drive unit 9 so that the output speed of the spindle 18 can be readily changed on site merely by replacing the gearbox 16 with another gearbox having a different gear ratio. A drill rod (not shown) is fixed to the bottom end of the spindle 18 for rotation therewith. As drilling proceeds, it is necessary to increase the length of the drill string.This may be accomplished by detaching the topmost drill rod from the spindle 18, by pivoting the drive unit 9 about its pivot points 10 to the position shown in dotted lines in Figures 1 and 2, by inserting a new drill rod in the spindle, by moving the carriage 8 and drive unit up the mast 5 (during which the new drill rod is slowly brought into the vertical POsition over the existing drill string), and by pivoting the drive unit back to its normal position and connecting the new drill rod to the drill string.

Whilst the drill string is detached from spindle 18 it is held in place by means of clamps (not shown) on the bottom working table 7.

At the top, the spindle 18 is bolted to a top plate 23. As can be seen in Figure 5, one part 24 of a stellite faced mechanical seal is provided within an annular recess in a seal top cover 25 which is bolted to the top plate 23. This seal part 24 is biased by means of a spring 26 against the other part 24a of the stellite faced seal. An O-ring 27 completes the seal. The interior of the housing 19 is formed with lubrication galleries such as 28 which are fed with lubricant from an independent source (not shown). This lubrication system provides better lubrication than was possible with the known types of drive units, and so drilling can be carried out at higher speeds.Moreover, the improved sealing arrangement 24,27 ensures that, during reverse circulation drilling, cutting debris which is forced up the interior of the spindle 18 and out through the gooseneck assembly 17 cannot contaninate the lubrication supply.

The gooseneck assembly 17 (see Figure 6) is generally T-shaped, the ends of the bar of the T forming pivot points 29 by means of which the drive unit 9 is pivoted to the pivot points 10 of the carriage 8. The entire assembly 17 is bolted to the housing 19 so as to surround the top plate 23 (see Figure 5) and so that the seal 24,27 prevents cutting debris reaching the internal lubrication galleries 28 of the rotary head 15. The gooseneck assembly 17 includes a venturi tube 30 which is used during the initial stages of reverse circulation drilling to create a lift for debris from the hole. During direct circulation drilling this tube 30 is replaced by an air or water pressure line (not shown).Similarly, a blanking plate 31 is fitted during direct circulation drilling, but is removed for reverse circulation drilling so that the water and cutting debris can be discharged through this branch of the T-bar.

Thus both direct and reverse circulation drilling can be carried out with the minimum of modification and with the gooseneck assembly 17 permanently in position.

It will be apparent that the drive unit described above has many advantages of the prior art units. In particular: (i) It is a more compact, versatile unit.

(ii) The internal lubrication system en ables higher drilling speeds.

(iii) Speed and torque changes to suit different drilling requirements can be done simply on site using alternative auxiliary gearbox assemblies.

(iv) Pivot action takes place at the top of the gooseneck assembly, so that the geometry of the rig is simplified which leads to less overloading on the mast and hence reduced mast loading.

(v) The distance from hole to rig support jacks is reduced so that, for a given weight of rig, greater drill string weight can be handled.

(iv) With improved geometry and a more compact unit, a shorter mast is re quired for a given rotary head traverse.

vii) All hose runs are simplified.

viii) Change of drilling method from direct to reverse circulation can be achieved on site with negligible mod ification.

(ix) Contamination of the rotary head lubrication system with cutting debris is eliminated.

(x) The modular design allows the unit to be used with conventional rig equipment initially, and converted at a later date.

It will also be apparent that a number of modifications could be made to the drive unit and rig described above. Thus, the rig can be made to be even more versatile by providing masts of different lengths which can replace, on site, the mast 5.

WHAT WE CLAIM IS: 1. A drive unit for a drill rig, the drive unit comprising a rotary head and a gooseneck assembly, the rotary head having input drive means connectible to a motor via a gear box, and output drive means connectible to a drill rod, a hollow spindle constituting the output drive means, wherein the gooseneck assembly is connected to the rotary head with the interposition of a seal for excluding drilling debris from the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (12)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   of two sets of tapered roller bearings 20.

   The spindle 18 is driven by a worm gear 21 which engages within a hollow output shaft of the gearbox 16. A hydraulic motor 22 drives the gearbox 16. The gearbox is easily detachable from the rest of the drive unit 9 so that the output speed of the spindle 18 can be readily changed on site merely by replacing the gearbox 16 with another gearbox having a different gear ratio. A drill rod (not shown) is fixed to the bottom end of the spindle 18 for rotation therewith. As drilling proceeds, it is necessary to increase the length of the drill string.This may be accomplished by detaching the topmost drill rod from the spindle 18, by pivoting the drive unit 9 about its pivot points 10 to the position shown in dotted lines in Figures 1 and 2, by inserting a new drill rod in the spindle, by moving the carriage 8 and drive unit up the mast 5 (during which the new drill rod is slowly brought into the vertical POsition over the existing drill string), and by pivoting the drive unit back to its normal position and connecting the new drill rod to the drill string.

   Whilst the drill string is detached from spindle 18 it is held in place by means of clamps (not shown) on the bottom working table 7.

   At the top, the spindle 18 is bolted to a top plate 23. As can be seen in Figure 5, one part 24 of a stellite faced mechanical seal is provided within an annular recess in a seal top cover 25 which is bolted to the top plate 23. This seal part 24 is biased by means of a spring 26 against the other part 24a of the stellite faced seal. An O-ring 27 completes the seal. The interior of the housing 19 is formed with lubrication galleries such as 28 which are fed with lubricant from an independent source (not shown). This lubrication system provides better lubrication than was possible with the known types of drive units, and so drilling can be carried out at higher speeds.Moreover, the improved sealing arrangement 24,27 ensures that, during reverse circulation drilling, cutting debris which is forced up the interior of the spindle 18 and out through the gooseneck assembly 17 cannot contaninate the lubrication supply.

   The gooseneck assembly 17 (see Figure 6) is generally T-shaped, the ends of the bar of the T forming pivot points 29 by means of which the drive unit 9 is pivoted to the pivot points 10 of the carriage 8. The entire assembly 17 is bolted to the housing 19 so as to surround the top plate 23 (see Figure 5) and so that the seal 24,27 prevents cutting debris reaching the internal lubrication galleries 28 of the rotary head 15. The gooseneck assembly 17 includes a venturi tube 30 which is used during the initial stages of reverse circulation drilling to create a lift for debris from the hole. During direct circulation drilling this tube 30 is replaced by an air or water pressure line (not shown).Similarly, a blanking plate 31 is fitted during direct circulation drilling, but is removed for reverse circulation drilling so that the water and cutting debris can be discharged through this branch of the T-bar.

   Thus both direct and reverse circulation drilling can be carried out with the minimum of modification and with the gooseneck assembly 17 permanently in position.

   It will be apparent that the drive unit described above has many advantages of the prior art units. In particular: (i) It is a more compact, versatile unit.

   (ii) The internal lubrication system en ables higher drilling speeds.

   (iii) Speed and torque changes to suit different drilling requirements can be done simply on site using alternative auxiliary gearbox assemblies.

   (iv) Pivot action takes place at the top of the gooseneck assembly, so that the geometry of the rig is simplified which leads to less overloading on the mast and hence reduced mast loading.

   (v) The distance from hole to rig support jacks is reduced so that, for a given weight of rig, greater drill string weight can be handled.

   (iv) With improved geometry and a more compact unit, a shorter mast is re quired for a given rotary head traverse.

   vii) All hose runs are simplified.

   viii) Change of drilling method from direct to reverse circulation can be achieved on site with negligible mod ification.

   (ix) Contamination of the rotary head lubrication system with cutting debris is eliminated.

   (x) The modular design allows the unit to be used with conventional rig equipment initially, and converted at a later date.

   It will also be apparent that a number of modifications could be made to the drive unit and rig described above. Thus, the rig can be made to be even more versatile by providing masts of different lengths which can replace, on site, the mast 5.

   WHAT WE CLAIM IS: 1. A drive unit for a drill rig, the drive unit comprising a rotary head and a gooseneck assembly, the rotary head having input drive means connectible to a motor via a gear box, and output drive means connectible to a drill rod, a hollow spindle constituting the output drive means, wherein the gooseneck assembly is connected to the rotary head with the interposition of a seal for excluding drilling debris from the

   interior of the rotary head, and wherein the gooseneck assembly is provided with a pair of co-axial pivot points for attaching the drive unit to a carriage movable along the mast of the drill rig, the axis of the pivot points passing through the outlet of the gooseneck assembly.
2. 2. A drive unit as claimed in claim 1, wherein the gooseneck assembly is provided at the top of the rotary head.
3. 3. A drive unit as claimed in claim 1 or claim 2, wherein the gooseneck assembly is of T-shape form, the bar of the T forming the pivot points.
4. 4. A drive unit as claimed in claim 3, wherein the outlet of the gooseneck assembly is provided at one end of said bar.
5. 5. A drive unit as claimed in claim 5, wherein a venturi tube is detachably mounted inside said bar adjacent the other end thereof.
6. 6. A drive unit as claimed in any one of claims 1 to 5, further comprising a gearbox detachably mounted on the rotary head and in drivable engagement with the input drive means.
7. 7. A drive unit as claimed in any one of claims 1 to 6, wherein the rotary head is formed with internal lubrication galleries fed by an independent lubricant supply.
8. 8. A drive unit for a drill rig substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawings.
9. 9. A drill rig comprising a wheeled support vehicle, a mast pivotably mounted on the vehicle, a carriage movable along the mast, and a drive unit pivotably attached to the carriage, the drive unit being as claimed in any one of claims 1 to 8.
10. 10. A drill rig as claimed in claim 9, wherein the vehicle is provided with hydraulic support jacks.
11. 11. A drill rig as claimed in claim 9 or claim 10, wherein the vehicle is a trailer.
12. 12. A drill rig substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawings.