US 3594106 A
Description (OCR text may contain errors)
United States Patent  Inventor Marion A. Garrison Denver, C010.
(21] Appl. No. 823,301  Filed May 9, 1969  Patented July 20, 1971  Assignee Empire Oil Tool Company Denver, C010.
 VARIABLE SPEED MOTOR DRILL 230/137, 140; 418/153, 202 ;9l/l56, 119; 123/17; 103/117, 140, 216 M;415/502  References Cited UNITED STATES PATENTS 2,636,478 4/ 1953 Smyser 2,753,809 7/1956 Garrison 103/117 FOREIGN PATENTS 786,999 11/1957 Great Britain 418/153 Primary Examiner-Henry F. Raduazo Atlorney-McGrew and Edwards ABSTRACT: A down-hole rotary drilling tool adapted to be driven by hydraulic or pneumatic power with the latter under control of a centrifugal speed regulator establishing drilling speed independently of torque loads. The drilling tool being connected to drill pipe string for suspending the drill bit in formation has novel-type thrust and motor bearings, including load-modifying means responsive to compression or tension loads on shaft causing loads to be applied as compression loading on thrust bearing. Axially adjustable bearings for motor accept radial and thrust loads. Novel blade arrangement for rotor prevents binding from blade distortion due to pressure of flowing liquid. Pressure relief valve and internal rotating dump valve relieve against excessively high and minimum low pressures in flow through tool.
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3 56 mmmm FIG 9 PATENT ED JUL20 I9?! VARIABLE SPEED MOTOR DRILL My invention relates to a deep well-drilling apparatus of the type employed at the bottom of drill pipe strings in rotary drilling of wells. More specifically, the present invention represents improvements in the general arrangement and operation of a deep well motor drill of the type disclosed and claimed in my U.S. Pat. No. 3,076,514, dated Feb. 5, I963, assigned to the assignee of the present invention. The present invention employs a novel type of blade and rotor combination adapted to function as the rotor of a down-hole motor for rotary drilling but which also will be equally effective in the rotor of pumps, such as positive displacement pumps where a series of such blades impart an impelling movement to the fluid being pumped.
Another innovation of the present invention is the provision of a novel type of thrust bearing for the shaft of the drilling tool which has load-modifying means responsive to either compression or tension loads on the shaft and movable thereby so as .to cause such loads to be applied only as compression loading on the thrust bearing. A generally similar type of bearing assembly is provided for the rotor of the drilling tool, which is axially adjustable so as to permit said rotor to accept both radial and thrust loads.
In one embodiment, the assembly comprises a down-hole, pneumatically powered, rotary drilling tool which has centrifugally actuated means within the tool regulating its speed independently of torque loads and capable of passing the full flow of the pneumatic fluid supply through the tool and out of the drilling bit without reducing the rate of flow.
Still another innovation of the present drilling tool when operated as a hydraulically powered unit is the utilization of a pressure relief valve in the tool relieving fluid pressure above a predetermined maximum and having associated therewith an internal rotating dump valve arranged to remain closed in the presence of a rapidly moving column of fluid and opening when the velocity of said column drops below a predetermined minumum.
Accordingly, it is an object of my invention to provide a simple, durable and efficient power unit for a deep well motor drill which employs a novel blade and rotor combination in the power unit which has the component parts arranged to substantially avoid binding action even when the blades of the rotor are subjected to extreme pressures over substantial time periods.
Another object of my invention is to provide a novel type of thrust bearing assembly for the shaft of the drilling tool of such a power unit which is durable, economical and efficient and operates within the drilling tool in association with load-modifying means responsive to either compression or tension loads on the shaft and movable thereby so as to cause such loads to be applied only as compression loading on the thrust bearing.
A further object of my invention is to provide a simple, economical and efficient rotary drilling tool which has centrifugally actuated means for regulating the speed of the tool independently of torque loads.
Yet another object of the invention is the provision of an arrangement of associated valves, inclusive of a pressure relief valve relieving fluid pressure in the tool above a predetermined maximum, and an internal rotating dump valve arranged to remain closed in the presence of a rapidly moving fluid column and opening when the velocity of said column drops below a predetennined minumum so as to maintain a desired flow within the tool.
Other objects reside in novel combinations and arrangements of parts and novel details of construction, all of which will be set forth fully in the course of the following description.
The practice of my invention will be best understood by reference to the accompanying drawings illustrating a preferred embodiment of a deep well motor drill assembly. In the drawings, in the several views of which like parts bear similar reference numerals,
FIG. 1 is an illustration ofa deep well motor drill embodying improvement features of the present invention and shown as being in a depending position within a well; 1
FIG. 2 is a vertical central section drawn to an enlarged scale of one embodiment of improved speed control valve assembly incorporated in the motor drill assembly shown in FIG.
FIG. 3 is a vertical central section of a portion of the motor drill assembly adjoining the assembly of FIG. 2 in depending relation and illustrating a new bearing arrangement and motor assembly which has been very effective;
FIG. 4 is a vertical central section illustrating the lower end of the motor drill assembly, particularly a novel type of thrust bearing assembly, and certain flow control features of the motor drive;
FIG. 5 is a composite horizontal section showing both inlet and discharge ports and taken approximately on the lines 5-5, FIG. 3, and also having its position indicated in FIG. 1;
FIG. 6 is another horizontal section taken approximately on the line 6-6, FIG. 3, and also having its position indicated in FIG. 1;
FIG. 7 illustrates the speed-regulating unit of the present invention also shown as a horizontal sectional view taken ap proximately along the line 7-7, FIG. 2;
FIG. 8 is an enlarged fragmentary view of the wiping blade and associated rotor recess similar to the arrangement shown in FIG. 5 and with the projections on the exterior surface of the blade shown in supporting relation to surfaces of the groove or recess in which they are disposed; and
FIG. 9 is a vertical section through a combined pressure relief valve and drain valve used in the drill assembly when it is using a hydraulic drive.
DRILL ASSEMBLY As shown in FIG. I, the motor drill assembly 10 of the present invention is carried in a length of nonrotating drill pipe 11, the several sections of which comprise the drill string I2 extending from the surface at the top of the well 13 (not shown) where the string is rotated, to the bottom 14 of the well where a bit 15 carried at the lower end of the string 12 is disposed in a position to cut engaged portions of the formation 16 at the well bottom 14. While the drill assembly 10 of the present invention may utilize either a hydraulic or a pneumatic power source for its operation, it will be described as actuated by circulation of pressurized drilling mud from the surface through string 12 into the well hole 13 which in addition to providing the rotation for bit 15 also acts as a coolant for the bit and removes cuttings from well bottom 14 upwardly to the surface outside drill string 12.
Drill bit 15 may be of any standard or preferred type and is secured by a lower collar member 17 (FIG. 4) which is at tached to, preferably integrally, a drill shaft 18 as shown at 19. The lowermost drill pipe section Ila of drill string 12 has a threaded rubber-lined bearing bushing 21 which holds the thrust bearing assembly in place. At its upper end, drill string I2 is supported by a hollow cylindrical member 22 having a threaded portion 23 at its top (FIG. 2) which is threadedly secured on suitable supporting structure at the top of well 13 (not shown) which is used in lowering or raising the string as required and supplies the power requirements of the drilling operation, either as circulating drilling fluid, such as drilling mud, or by pneumatic injection. Cylindrical member 22 has a threaded connection 23 with the upper end of drill pipe 11 as shown in FIG. 2.
Speed Regulation-Pneumatic Drive A speed control valve assembly 25 for use when drilling is to be by air/gas operation is supported within the hollow interior of member 22 and includes an upper nose member 26 having a depending weight member 27 secured in a recessed portion of the nose and depending therefrom in closely spaced relation to a tubular body portion 28 forming an extension of nose member 26. Although initially formed as separable pans, nose member 26 and body 28 are welded as an integral unit. A valve member 29 has a series of radial openings or ports 30 for conducting flow between the interior hollow portion of cylindrical member 28 and the interior of valve 29. A torsion spring 31 is mounted on a spacer 32 on the exterior of valve body 28. A spring adjusting clamp 33 is held on the exterior of body 28 by cap screws 34 and an adjoining clamp 35 is also secured on body by cap screws 36 or other suitable fastenings. A central ore 37 extends from the lower. end of valve body 28 to the lower end of drill string 12.
The valve assembly 25 is what may be designated a centrifugally controlled speed regulator valve and operates in conjunction with air/gas supply as the power source. When compressed air or gas is used as the circulating medium of the drilling operation, it is very important that the flow is not impeded when the drill string is in the hole and particularly if on or near the bottom. Cuttings and dust settle to the bottom if the air/gas supply is cut off or reduced to a point where the velocity of the upflow in the annulus is insufficient to carry the cuttings out of the bore hole and a drill string may be stuck by reason of such settling.
The speed regulator assembly 25 does not'cut off or reduce air supply. It controls speed by decreasing the inlet pressure against the motor and increases the back pressure against the discharge. Gas continues to pass through the tool as long as the motor continues to operate. FIG. 2 shows valve 25 with the ports 30 open. In normal operation during drilling, they are closed and only open when a predetermined speed is exceeded. When the ports 30 open, air is bled through the central shaft of the tool and reduces pressure against the inlet ports 50 of the motor. At the same time, some of the air which is being bypassed through the interior bore 37 builds up a back pressure through holes in the coupling 35. This changes the pressure relationship between the inlet port 50 and the discharge port 504, reducing the power and consequently the speed. The calibration of the valve is accomplished by means of torsion spring 31 and the adjustable clamp 33. By loosening this clamp and twisting, torsion is increased or decreased by a slight amount.
Motor Bearing Assembly A bearing body 38 has an externally threaded portion which is connected to the internally threaded motor housing 49 of motor 48. Body 38 encloses a lengthwise annulus 41 of substantial length acting as an oil storage receptacle which is closed on one end by an equalizer piston 42 having polypak seals 43 contacting inner bushing 39. Inner bushing 39 projects slightly beyond the upper end of bearing body 38 and is in contact with the threaded adjustment clamp 35. At the other end, inner bushing 39 contacts the inner race of bearing 44 to hold rotor shaft 55 firmly in axial adjustment. Ball bearing 44 is at the other end of receptacle 41 and a plug 54 acts as a seal for the lower end of the oil receptacle 41. Plug 54 forms an internal closure for ball bearing 44. This arrangement provides axial adjustment of said bearings to permit an associated rotor to accept both radial and thrust loads and to be effectively lubricated.
Investigations with a similar type of drilling unit using a different type of thrust bearing have disclosed that under heavy loads the bearing absorbs as much as 50 percent of the total power of the motor itself. The former bearing assembly had sleeve bearings with flat rubber faces and utilizes mating flat discs. Similar shapes were included in the thrust bearing. In order to improve the efficiency of the tool and make more of the torque developed by the motor available for rotating the bit, I decided to install antifnction bearings in both the motor and thrust bearing.
To replace the former thrust bearing arrangement, a new type of antifriction bearing has been installed, both as a motor bearing and as a thrust bearing. Considering the motor bearings first, I have a combined sealed ball thrust and radial bearing described hereinbefore. A feature of the ball bearing 44 for the motor is a floating equalizer or piston 42 which is exposed to the hydrostatic pressure of the well fluid when the latter is used as the power source for drilling. The purpose of this floating piston 42 is to separate drilling mud, which usually contains grit, from the clean oil needed to lubricate the bearings 44. Seals 43, 43a, etc. are placed for the purpose of keeping the oil in and dirt and grit out. There is a substantial reservoir 41 of oil and the reason the piston 42 is allowed to float is that if oil leaks out, the hydrostatic pressure in the well will move the piston against the remaining oil and thereby keep the grit out of the bearing. A similar ball bearing assembly 44a has been shown at the lower end of motor unit 48 (FIG. 3) which has identical components, and the same reference numerals have been applied thereto. Consequently, detailed description appears unnecessary.
HYDRAULIC MOTOR FIGS. 2 and 3 together with the sectional views 5 and 6 show the structural details of the hydraulic motor unit generally designated 48 and including a shell or housing 49 containing a rotor 55 having a central bore or passage portion 37 which is a part of the previously described bore 37. Housing 49 is supported in drill string 12 as a stationary member of the assembly and encloses a plurality of motor sections, which in the form illustrated comprise five motor sections having ports and one motor section having no ports, the uppermost two sections being inlet sections having inlet ports 50, the three lower sections having outlet ports 50a, and the intermediate motor section having no ports and being located between the upper inlet motor sections and lower outlet motor sections. Preferably, replaceable wear liners 56 are provided for all said sections and these liners have ports or openings aligned with the openings 50 and 50a.
The rotor 55 has a plurality of peripherally spaced recesses or slots 55a and an elongated blade member 51 has a hinged mounting in each slot 55a disposing an upper, pressure-resisting surface portion of the blade 51 inclined with respect to the upper edge of the slot 55a so that each blade has only limited travel relative to the inclined edge 55m. The position of the blades or vanes 51 changes from one in which their exposed outer surfaces flex during contact with the flowing mud and a second fully collapsed position with the associated recess resulting from blade engagement with a plurality of separator strips 49x secured to the motor housing 49 by screws 52x.
The number of vanes preferably is an even number, here shown as four, for the two mud chambers shown. The vanes are uniformly spaced around rotor 55 and the recesses 55a are slightly less in width than the separator strips 49x, while the spacing between channels or recesses 55a is slightly greater than the width of the separator strips 49x. The inlet ports 50 .are opposed for the respective chambers, and each such port is disposed immediately at that edge of the near separator strip which faces the direction of travel of the rotor shaft which is clockwise as indicated by the arrow in FIG. 8.
Pressurized mud descending through the inlet ports 50 from the space exteriorly of housing 49 flows across the extended surfaces of blades 51 and thereby imparts the rotation. Vanes or blades 51 being formed of rubber or other suitable flexible material, tend to assume the indicated extended position shown in FIGS. 5 and 8. The extended portions of blades 51 are restrained from further yielding to the applied forces by the provision of inner reinforcement members 51a (FIG. 8) and the edge 55m functioning as a stop member and are directed away from the direction of travel so that the outer edges of blades 51 engage with the wear liners 56 and prevent pressurized mud from being forced past the vane edges.
The pressurized mud descending through the motor unit 48 reaches the lower motor sections having the discharge ports 50a which are disposed along the near edge of the remote separator strip 49x at the far side of the chamber. The mud is then directed out of chambers 55x and returns to the annular space between drill pipe 11 and the motor housing 49. By providing more blades 51 than chambers 55x, such as the illustrated 4:2 arrangement, vane surfaces are always proximate to the entering mud flow when other vanes are collapsing and passing strips 49x. This has the effectof forming two mud flows in each chamber 55x so that when a forward vane is reaching the discharge ports 500 the next following vane has reached the inlet 50 position and is ready to be acted on by entering mud. High-speed and high-power rotation results.
THRUST BEARING ASSEMBLY Referring next to the ball thrust bearings 57, best shown in FIG. 4, this assembly is provided to utilize separate ball 57x or roller thrust bearings (not shown) which accommodate thrust incompression. This is accomplished by allowing shaft 18 to move up or down slightly in response to load. This arrangement allows the thrust bearings 57 to take their own proportionate share of the load by reason of the yielding under compression of rubber pads 68. Since all of the pads 68 are formed by the same molding operation, they accommodate essentially the same amount of compression.
As shown in FIG. 4, upper drill shaft 18 terminates in a reduced portion acting as a male coupling member 58 interfitting with a locknut 59 and a lower abutting locltnut 60 to secure the thrust bearing assembly 57 aided by the arrangement of retainer 61. A roller bearing carrier 63 has "polypak" seals 62. A tubular member 72 acts as a housing for the bearing assembly 57 and encloses a bushing 73. A pipe plug 74 is provided to close a lubricant supply inlet. A piston 75 having an O-ring seal 76 is held by the lower end of tube 77. A split spaces 78 separates the floating seal bushing 73 and associated lower end tube 77. A locknut 81 secures a rotating ring 82 at the upper end of threaded connection whilea threaded outer housing 83 is an extension of drill pipe ll and has a threaded conneetionwith drill shaft bearing 84 as shown at 85. 1
The principle of oiling the thrust bearing is the same as in the motor bearing. Rubber-lined bearing 21 has a left hand thread so that it does not unwind or loosen with right-hand rotation. By loosening the bearing 21 and moving it back an inch or so, the shaft 18x is permitted to drift down and create some space and also remove part 78 which is a split spacer. The purpose of this is to make replacement of seals 80 quick and easy. I
Pressure Relief and Drain Valve for Hydraulic Motor theend of a spring-biased poppet valve 106 normally closing an internal lock screw 107 and stop 108 of the relief valve 102 which bear against the lower end of a spring 105 confined in poppet 106. Spring 105 will be compressed by excessive pressures in the circulating drilling fluid but will return to its expanded position under the normal circulating pressures encountered in operation.
The drain valve body 115 adjoins the relief valve 102 and has a hollow upper portion in which a flexible disc 109 of the drain valve is secured in a recess of a drain valve poppet 110. An O-ring 111 provides a seal between drain valve body 115 and poppet 110. A drain valve spring 112 seats on a shouldered bushing 113 movable along a lower portion of the poppet and a nut 114 is connected to the lower end of the poppet so as to limit downward movement of bushing 113 under forces directed from spring 112..
The central bore 37 previously described includes the bore of drain valve 115 and extends through substantially the length of drill string 12 and into drill bit 15. The lower end of drain valve body 115 has a threaded connection with the top locknut 118 of the motor assembly, the latter being secured by a lock screw 116 with a soft plug (not shown). A thrust nut 119 fastened by a capscrew 120 secures this assembly at the top of motor bearing assembly. The parts numbered 118, 119 and 120, respectively, in FIG. 9 are in essential respects the same as parts 33, 35 and 36, respectively, of FIG. 2.
In the parts arrangement of the present invention, the combined actions of the pressure relief valve 102 and the drain or dump valve "5 is a means of draining the drill string 12 of fluid as it is withdrawn from the well. The dump valve 115 has the relief valve [02 built into its top portion. This arrangement includes use of the rubber ring or flexible disc 109. Fluid coming from the well in considerable volume tends to bear against the disc 109 which deflects and forms a cuplike shape and vkeeps a load against the dump valve, thus Keeping it closed during the time the pump is delivering fluid through the tool.
Blade-Type Motor Reference hasbeen made in the preceding description to the motor unit 48 having a blade member 51 mounted on rotor 55. The structure thus far described is essentially the same as that shown and described in U.S. Pat. No. 3,076,514. However, substantialimprovements in'the blade and rotor arrangement have been incorportated in the present drawings and will now be described. From experience with the structural arrangement of said'patent, l have determined that under the high-pressure conditions, there is a tendency for the blade to move backward and to roll with-respect to the rotor. The greater'the pressure against the blade, the greater the tendency for the blade'to rollbackwards because pressure tends to make the blade tum backwards. When, it does turn backwards, itcreates a load between the lower edge of the blade and the wiping edge which puts that blade under a highcompression situation due to'the fact that a motor drill which is of suffcient'power to drive a drilling bit must be operated under considerable pressure.
It was recognized'that a flexible blade would require reinforcements. The usual reinforcement creates stiffness in the blade and'tends to lock the blade against the wall of the fluid motor. In order to preventthe locking due to high pressure and also to increase the life of the wiping edge of the blade, I
have resorted to two innovations. First, I have created a space between the lower comer of the blade and the lower corner of the slot in which it is fitted. Then I have provided small projections 90, preferably in the form of cylindrical buttons, which are spaced aboutl inch apart and are made of a soft resilient elastomer, such as neoprene. As clearly shown in FIG. 8, the buttons bear against the bend 9 1 and keep the wiping edge of the blade, such as blade 51, in contact with the wall or surface of recess 55a between bend 91 and the inclined edge These buttons 90 are sufficiently resilient so that as pressure tends to push the blade out against the wall, the buttons will yield to a degree. which keeps the wiping force against the wall I within very reasonable limits, thus extending the wear life of the wiping edge of the blade 51. ln addition, the shape of slot or recess 55a is designed to resist backward movement of the blade and the holddown strip is made in such a way that it comes very close to contact with the inside corner of the blade when there is no load on same. When a pressure load develops, there is a slight tendency for the blade to rock over the corner of the slot and the holddown'strip takes the reaction. By reason of the present arrangement, the blades function as means to discharge fluid that otherwise would be trapped as the blade touches the inclined edge 55m. At that instance, the tendency to trap fluid and cause a buildup of a predetermined number of spaced apart longitudinal extending blades mounted on the outer periphery of said rotor body, each of said blades being made of a resilient, flexible material and having one of its longitudinal edges secured against said rotor body to form a blade corner about which said blade is flexed and the free portion of said blade'pivots due to its resilience to swing its other longitudinal edge into a frictional, sealing engagement with the wall of said bore, the free portion of each of said blades being reinforced so as to prevent bending due to fluid pressure;
stop means mounted on said rotor body and associated with each of said blades to engage the free portion of said blade to limit its angle of swing, the junction of each of said stop means with said rotor body forming a lower corner adjacent said blade comer so as to define a space between said lower comer and said blade comer; and
resilient means mounted in each of said spaces, said resilient means being operable to yield to said blades as a function of pressure applied to the free portions thereof so as to cooperate with said stop means to prevent said blades from binding with the wall of said bore.
2. The invention recited in claim 1, wherein said resilient means are a plurality of cylindrical buttons spaced apart longitudinally along said blades between said blade corners and said lower comers defined by said stop means and said rotor body.
3. The invention recited in claim 1, wherein said stop means limits the angle of swing of each of said blades to an acute angle. Y
4. The invention recited in claim 1, wherein the free portion of each of said blades is reinforced to prevent bending by disposing a reinforcing member therein.
5. The invention recited in claim 1, including replaceable wear liner means mounted in said bore.
6. in a fluid motor or pump having a housing with a hollow bore therein and'a rotor body mounted for rotation in said bore, the improvement of said rotor body having a predetermined number of spaced apart longitudinal slots defined in its outer periphery; a flexible, resilient blade mounted in each of said slots; each of said blades having one of its edges secured against the bottom of one of said slots to form a blade corner about which said blade is flexed and the free portion of said blade pivots due to its resilience to swing its other edge into a frictional, sealing engagement with the wall of said bore; the free portion of each of said blades being reinforced so as to prevent bending due to fluid pressure and each of said slots having a sidewall to engage the free portions of said blades and limit their angles of swing out of said slots; the junction of the bottom and said sidewall of each of said slots forming a lower comer adjacent said blade corner so as to define a space between said lower comer and said blade corner; and resilient means mounted in each of said spaces which are operable to yield to said blades as a function of pressure applied to the free portions thereof so as to cooperate with said sidewalls of said slots to prevent said blades from binding with the wall of said bore. T v I 7, The invention recited in claim 6, wherein said sidewall of each of saidv slots limits the angle of swing of each of said blades to an acute angle.
8. The invention recited in claim 7, wherein: each of said blades has its one edge secured to the bottom of one of said slots by a holddown-strip; said resilient means are a plurality of cylindrical buttons spaced apart along said blades between said blade corners and said lower corners of said slots; and the .free portion of each of said blades is reinforced to prevent bending by disposing a reinforcing member therein. 9. In a fluid motor or pump, the combination comprising:
a housing defining a hollow bore;
a rotor body mounted for rotatronm sald bore, said rotor body having a predetermined number of spaced apart longitudinal slots defined in its outer periphery, each of said slots having a bottom wall substantially perpendicular to an imaginary radius drawn from the center of said rotor body and a sidewall at an acute angle to said bottom wall and forming a rounded corner therewith;
a flexible, resilient blade mounted in each of said slots, each of said blades having one of its edges secured against said bottom wall of one of said slots to form a blade corner about which said blade is flexed and the free portion of said blade pivots due to its resilience to swing out of said slot against said slot sidewall and into a frictional, sealing engagement with the wall of said bore, the free portion of each of said blades being reinforced so as to prevent bending due to fluid pressure, each of said slots being formed and said blades being mounted therein to define a space between said rounded slot corner and said blade comer; and
spaced apart resilient buttons mounted in each of said spaces which are operable .to yield to said blades as a function of pressure applied to the free portions thereof so as to cooperate with said sidewalls of said slots to prevent said blades from binding with the wall of said bore.
10. In a fluid motor or pump having a housing with a hollow bore therein and a rotor body mounted for rotation in said bore, the improvement comprising:
blade means pivotally mounted on said rotor body, said blade means being made of a flexible material and being operable to swing outwardly from said rotor body into a frictional, sealing engagement with the wall of said bore, the portion of said blade means swinging outward from said rotor body being reinforced so as to prevent bending due to fluid pressure;
stop means for limiting the angle of swing of said blade means; and
resilient means positioned between said blade means and said rotor body which are operable to yield to said blades as a function of pressure applied to said blades so as to cooperate with said stop means to prevent said blades from binding with the wall of saidbore.