GB2355036A - Cutting Tool - Google Patents

Abstract

A cutting tool assembly generally for use in enlarging boreholes comprises a body 1 and three cutting assemblies each housing a cutter 12 mounted on a spindle 13 retained between outer 150 and inner 150 saddles. The cutter may be conveniently replaced by a different sized cutter when enlarging the hole to a greater or lesser diameter. The disposition of the cutter may also be altered by replacing the inner saddle with saddles of different sizes for the same end. Considerable tool downtime may be saved as there is no need to remove the tool body from a drill string during drilling. The inner saddle is retained via slots 15s and a clamp block 17. The outer saddle bolts to the inner saddle.

Description

2355036 1 1 "Cutting Tool" 2 3 This invention relates to a cutting tool.

The 4 invention is particularly useful for drilling for 5 water, oil and gas wells and in drilling for civil 6 engineering purposes. Certain embodiments relate to 7 a hole opener or cutter for use in enlarging and 8 finishing boreholes from an initial pilot borehole. 9 10 Hole openers are well known for enlarging the 11 diameter of boreholes. Hole openers generally 12 comprise an array of cutters arranged on spindles and 13 mounted on the outside of a tool body. 14 15 According to the present invention there is provided 16 a rotary cutting tool comprising a body and.-at least 17 one cutter on the body, wherein the cutter is 18 replaceable in order to vary the cutting diameter of 19 the tool. 20 2 1 The cutter is preferably retained in the body by one 2 or more replaceable saddles, and the or each saddle 3 can be replaced itself by a saddle of the same or a 4 different size in order to accommodate different 5 sizes of cutters, or simply to mount the same size of 6 cutter a different axial distance from the body so as 7 to vary the cutting diameter of the tool. Typically, 8 there are two saddles in a single saddle assembly 9 which between them retain each cutter on the body to 10 form a cutter assembly. The inner saddle(s) are 11 typically secured to the body by a set of keys 12 machined in recesses on the body, and may be locked 13 in place by one or more clamps or blocks which can be 14 attached to the body via fixings such as screws or 15 bolts etc. The outer saddles can be secured by 16 similar means to the body or to the inner saddles or 17 by bolting them to the inner saddles. This allows 18 the inter-changing of different sizes of cutters 19 and/or saddle assemblies on the same tool body 20 thereby obviating the need to remove the tool body 21 from the drill string when enlarging the hole to a 22 greater diameter, which saves on downtime. Certain 23 embodiments of the invention also obviate the removal 24 and re-welding of conventional fixed cutter 25 mountings, either in situ or in a repair facility. 26 27 More than one cutter can be provided, and typically 28 three cutters are provided at circumferentially 29 spaced locations on the body of the tool. The 30 cutters can be located at the same point along the 3 1 axis of the tool, or can be spaced along the axis 2 from one another. 3 4 Each cutter assembly preferably comprises a cutter 5 mounted on a spindle and having a bearing such as 6 ball and/or roller bearings with an inner and outer 7 race. The inner race is typically prevented from 8 turning by the spindle which runs through it and is 9 held by an outer and inner saddle. The turning 10 motion of the tool in one direction rotates the outer 11 race of the cutter in the other as it bears against 12 the wall of the hole, and provides the cutting 13 action. The spindle of the cutter assembly is 14 typically held between outer and inner saddles and is 15 prevented from turning by a tang or spline machined 16 on one (eg the inner) end of the spindle and a mating 17 piece in the corresponding saddle or in the tool 18 body. A spindle retaining pin may be provided to 19 pass through the outer saddle to prevent the spindle 20 from migrating out of the tool. 21 22 One or more jetting nozzles machined in the body can 23 allow fluid circulation from a conduit in the tool 24 (eg in the central bore) into the annulus around the 25 tool to assist in cuttings removal and to prevent the 26 tool from reaching excess temperatures and 27 overheating. 28 29 Certain embodiments of this invention relate to the 30 construction of outer and inner saddles and the way 31 in which they are held in the body of the tool by a 4 1 series of keys machined in the recesses of the body 2 and then secured in place by one or more clamps, 3 optionally in the form of clamp blocks. one 4 advantage of fastening the saddles in this way is the 5 ability to change the saddles so as to expand or 6 contract the cutting diameter of the tool whilst 7 using the same body cutters and outer saddles. 8 9 One or more clamp blocks are used to secure and hold 10 each of the inner saddles in place whilst outer 11 saddles are held to the inner saddles by one or more 12 screws, bolts or similar fixings. Different 13 embodiments of the invention employ different fixing 14 means and different designs of saddle. 15 16 The ability to change the inner saddles with general 17 hand tools allows changes in the tool's cutting 18 diameter with minimum effort and produces a multi19 gauge hole opener for enlarging boreholes. 20 21 The bearings on the cutter assembly are preferably 22 recessed to accept roller and ball bearings and may 23 be adapted to take thrust and/or axial loads applied 24 to them. Typically a set of seals are provided 25 between the races to prevent the loss of grease from 26 the bearings and also to protect the bearings against 27 the ingress of foreign particles entering the cutting 28 assembly. 29 1 An embodiment of the present invention will now be 2 described by way of example and with reference to the 3 accompanying drawings in which:

4 Fig. 1 shows a side and end view of one 6 embodiment of an assembled tool; 7 Fig. 2 shows a perspective view of an assembled 8 tool; 9 Fig. 3 shows a cutter assembly in assembled (A) and exploded (B) states; 11 Fig. 4 shows the tool body; 12 Fig. 5 shows three alternative designs of inner 13 saddle; 14 Fig. 6 shows a perspective side view of a portion of one tool having the inner saddle 16 shown in Fig. 5a; 17 Fig. 7 shows an end view of the Fig. S inner 18 saddles assembled into cutter assemblies; 19 Fig. 8 shows side views of the Fig. 7 cutter assemblies; 21 Fig. 9 shows a side view of the Fig. 6 tool with 22 a smaller saddle assembly; and 23 Fig. 10 shows an end view of the Fig. 9 tool.

24 Referring now to the drawings, a cutting tool 26 comprises a body 1 having a central bore 5 and box 27 and pin connections at its upper and lower end as are 28 conventionally known, for incorporation of the 29 cutting tool into a drillstring. The body 1 has three elongate recesses 7 arranged axially and spaced 31 circumferentially around its outer surface for 6 1 receiving the cutter assemblies to be described, each 2 recess having a pair of shoulders 7s extending into 3 the recess 7 on opposing sides thereof. 4 5 The inner bore 5 extends axially through the centre 6 of the tool 1, and has three branches 5b extending 7 from the central bore 5 to the outer surface of the 8 tool body 1 and emerging at nozzles 6 between the 9 recesses 7. The branches 5b and nozzle 6 allow the 10 ejection of drilling mud etc from the central bore 5 11 in between the cutters to displace drill cuttings etc 12 from the vicinity of the cutters 12 while the tool is 13 in use. 14 15 The recesses 7 are adapted to receive cutting 16 assemblies (Fig. 3) designated generally as 10 and 17 comprising a cutter 12 having outer teeth as 18 conventionally known and being rotatable about a 19 spindle 13 whose respective ends are held captive in 20 an outer 15o and inner 15i saddle. The outer and 21 inner saddles 15o, 15i fasten together via bolts 16 22 so as to lock the spindle 13 between the saddles 15o 23 and 15i. The cutter 12 is f ree to rotate within a 24 recess 15r formed between the outer and inner 25 saddles. 26 27 Each cutter 12 comprises an outer race 12o and an 28 inner race 12i. The inner race is mounted on the 29 spindle 13, and is splined or otherwise attached to 30 the spindle so as to prevent relative rotation of the 31 inner race 12i and the spindle 13. Between the inner 7 1 race 12i and the outer race 12o there is provided a 2 row of ball bearings and a separate row of roller 3 bearings (not shown) The row of ball bearings 4 prevents axial movement of the outer race 12o in relation to the spindle 13, and the roller bearings 6 bear the axial loads exerted on the cutter 12.

7 8 A tang 18 at the flattened end portion of the spindle 9 13 engages with a formation in the aperture 19 in the inner saddle 15i, so as to prevent rotation of the 11 spindle 13 relative to the saddle 15. A spindle 12 retaining pin 16 extends through a lateral wall of 13 the outer saddle 15o into the aperture for receiving 14 the outer end of the spindle 13, and prevents the spindle 13 from working loose of the saddle 15 during 16 use.

17 18 The inner saddle 15i has a slot 15s on each side 19 which is adapted to engage with the shoulder 7s on the inner sides of the recess 7, so that once 21 assembled, the saddle assembly 10 slots into the 22 recess 7 and is held there against radial movement by 23 the inter-engagement of the shoulders 7s and the 24 slots 15s. The inner saddle 15i is initially offered to the lower end of the recess 7 below the shoulders 26 7s and is subsequently slid upwards in the recess so 27 that the shoulders 7s engage in the slots 15s. At 28 that point, a clamp block 17 is fastened to the body 29 via bolts extending into the inner surface of the recess 7 at the bottom thereof so as to prevent axial 8 sliding of the cutter assembly 10 in the recess 7 2 when fixed in place.

3 4 Each of the three recesses 7 accommodates a respective cutter assembly 10 in the assembled tool, 6 and the rotation of the cutters widens the hole to 7 the extent of the radial extension of the cutters.

8 In the embodiments shown in Figs. 1 to 3, the cutter 9 assemblies 10 can be replaced by others with cutters which extend radially to a different extent so as to 11 adapt the tool for different sizes of hole.

12 13 In particular, in a second alternative embodiment, 14 the cutter 12 can simply be exchanged for a cutter of is a different diameter, eg a reduced diameter, so as to 16 widen the hole to a lesser extent than was previously 17 desired. This can be achieved simply by removing the 18 outer saddle 15o, replacing the cutter and the outer 19 saddle. Alternatively, the hole cutter assembly 10 can be removed and replaced with a different cutter 21 assembly bearing a cutter 12 having a different 22 diameter.

23 24 In other alternative embodiments, the same cutter 12 can be used, but its distance from the body of the 26 tool 1 can be varied by varying the size of the inner 27 saddle 15i so as to space it further away from or 28 closer to the body 1. In particular, if a larger 29 inner saddle 15i is used, the same cutter 12 will be displaced from the body 1 of the tool to widen the 31 hole to a greater extent. Equally, the saddle 15i 9 1 shown in Fig. 1 can be replaced with a different 2 inner saddle having a thinner profile so that the 3 cutter 12 is disposed closer to the body in order to 4 cut a smaller hole. 5 6 Therefore, by varying the dimensions of the cutter 12 7 and/or the inner saddle 15i, the same tool can be 8 redressed to cut wider or narrower gauges of holes. 9 10 Referring now to Figs. 5 to 10, alternative designs 11 of inner saddle 15i are shown in Figs. 5a, b and c 12 which show decreasing sizes of inner saddle 15i. The 13 Fig. 5 saddles function in exactly the same way as 14 described for the inner saddles 15i described above, 15 but clearly differ in the extent to which they hold 16 the cutter 12 away from the body of the tool 1. The 17 largest inner saddle 15ia is shown in use in the 18 assembled tool in Fig. 6 and in the assembled cutter 19 assembly in Figs. 7a and 8a, and the smallest inner 20 saddle 15ic is shown in the assembled tools of Figs. 21 9 and 10 and in the assembled cutter assembly of 22 Figs. 7c and 8c. 23 24 The inner saddles 15ia, 15ib and 15ic are 25 interchangeable and can each fit equally well into 26 the slots 7 for incorporation into the tool 1 as 27 shown in Figs. 6, 9 and 10, so that the radial 28 extension of the cutter 12 away from the tool body 1 29 can be varied in accordance with the size of the 30 inner saddle 15i that is used. 31 I Modifications and improvements can be incorporated 2 without departing from the scope of the invention.

Claims (2)

1 Claims

2 3 1 A cutting tool comprising a body and at least 4 one cutter on the body, wherein the cutter is replaceable in order to vary the cutting diameter of 6 the tool.

7 8

2. A cutting tool as claimed in claim 1, wherein 9 the or each cutter is retained in the body by one or more replaceable saddles (s) 11 12 3 A cutting tool as claimed in claim 2, wherein 13 the or each cutter is retained in the body by a 14 replaceable inner saddle and a replaceable outer saddle.

16 17 4 A cutting tool as claimed in claim 2 or claim 3, 18 wherein the or each saddle is replaceable by 19 saddle(s) of the same or a different size.

21 5. A cutting tool as claimed in claim 4, wherein 22 the or each saddle is secured to the body by means of 23 at least one male member on one of the saddle and the 24 body which engages a female member on the other of the body and the saddle.

26 27 6. A cutting tool as claimed in claim 5, wherein 28 the male member is a shoulder and the female member 29 is a recess.

12 1 7. A cutting tool as claimed in any one of claims 2 2 to 6, wherein the saddle (s) may be held in place by 3 one or more clamps.

4 8. A cutting tool as claimed in any preceding 6 claim, wherein the or each cutter is mounted on a 7 spindle.

8 9 9. A cutting tool as claimed in claim 8, wherein the spindle is held between the first and second 11 saddles.

12 13 10. A cutting tool as claimed in claim 8 or 9, 14 wherein the cutter can rotate on the spindle.

16 11. A cutting tool as claimed in any preceding 17 claim, wherein one or more jetting nozzles are 18 provided to allow fluid circulation from a conduit in 19 the body into the annulus around the tool.

21 12. A cutting tool as claimed in any preceding 22 claim, having three cutting assemblies, each cutting 23 assembly comprising a cutter, an outer saddle, an 24 inner saddle and a spindle.

26 13. A cutting tool as claimed in any preceding 27 claim, wherein the cutting tool can be incorporated 28 into a drillstring.

29 14. A cutting tool substantially as herein before 31 described with reference to the accompanying figures.