Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3866746 A
Publication typeGrant
Publication dateFeb 18, 1975
Filing dateAug 27, 1973
Priority dateAug 27, 1973
Also published asCA1014143A1
Publication numberUS 3866746 A, US 3866746A, US-A-3866746, US3866746 A, US3866746A
InventorsCurington Alfred R
Original AssigneeBakerdrill Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Rotary bore hole air hammer drive mechanism
US 3866746 A
Abstract
A hammer piston reciprocates in a housing and impacts against an anvil in the housing which is integral with a drill bit, a drilling string rotating the housing during the repeated impacting of the piston against the anvil. Torque is transmitted from the housing through a plurality of segments and a drive member to the anvil during the impacting action, transmission of the torque by the segments being effected through generally radial or off radial surfaces formed on the anvil and the segments which are perpendicular to the tangent of the drive so that the surfaces do not cam the segments outwardly against the housing.
Images(2)
Previous page
Next page
Description  (OCR text may contain errors)

United States Patent Curington Feb. 18, 1975 ROTARY BORE HOLE AIR HAMMER DRIVE MECHANISM Inventor:

US. Cl 173/73, 64/23, 173/78, 173/80, 173/131 Int. Cl. E210 1/12 Field of Search 173/17, 73, 78, 80, 64, 173/131, 132, 133; 403/356, 358; 64/23 References Cited UNITED STATES PATENTS 9/1971 Curington 173/17 X ..173/73 10/1971 Martini 12/1971 Vincent Primary ExaminerErnest R, Purser Assistant ExaminerWilliam F. Pate, lll Attorney, Agent, or FirmBernard Kriegel [57] ABSTRACT A hammer piston reciprocates in a housing and impacts against an anvil in the housing which is integral with a drill bit, a drilling string rotating the housing during the repeated impacting of the piston against the anvil. Torque is transmitted from the housing through a plurality of segments and a drive member to the anvil during the impacting action, transmission of the torque by the segments being effected through generally radial or off radial surfaces formed on the anvil and the segments which are perpendicular to the tangent of the drive so that the surfaces do not cam the segments outwardly against the housing.

19 Claims, 5 Drawing Figures ROTARY BORE HOLE AIR HAMMER DRIVE MECHANISM BACKGROUND OF THE INVENTION The present invention relates to drill bit apparatus for drilling a bore hole in a formation, and more particularly to pneumatically operated apparatus that imparts a percussive action to an anvil and drill bit integral therewith while the latter are preferably rotated.

During the impacting action of an air hammer piston against the anvil portion of a drill bit, the anvil and drill bit are rotated by rotating the housing of the apparatus, so that the face of the drill bit covers substantially the full area of the bottom of the bore hole being drilled in a formation, torque being transmitted from the housing to the anvil in certain well known apparatus through a key and keyway type of spline connection, in which a multiplicity of elongate keys and keyways are disposed circumferentially around the anvil and housing member associated therewith. Such key and keyway spline interconnections for transmitting torque between the housing and the anvil effect a substantial reduction in the cross-sectional area of the anvil throughout the length of the key and keyway portion, which results in loss of the air hammer energy transmitted throughout the length of the anvil and bit. This is believed to be due to the fact that the impacting of the hammer piston against the anvil creates longitudinal stress pulses which travel through the bit from the anvil end to the face end of the bit, which stress pulses or stress waves remain constant in magnitude until such time as they encounter a change in cross-sectional area of the bit, and at these changes in cross-sectional area, part of the pulse is reflected back and a smaller magnitude pulse continues in the original direction.

The pending application for U.S. Pat. Ser. No. 239,047, now U.S. Pat. No. 3,804,181 filed Mar. 29, 1972, discloses a torque transmitting spline type of drive between the housing and the anvil and bit, which has a laser decrease in cross-sectional area throughout its length than in the prior bits, resulting in a substantial decrease in the amount of energy lost through the bit as a result of reflections created by the transmitting of the longitudinal stress pulses from the upper end of the anvil to the lower drilling face of the bit. In addition,

the torque transmitting drive connection provided between the housing, usually a housing sub or member forming the lower end of the housing, and the anvil can be manufactured at a substantially reduced cost. Wear between the anvil and the torque transmitting parts engaging it is more uniform, such that the drive connection between the housing and anvil has a much longer life than prior types of drives, such as the key and keyway types heretofore used. Moreover, when wear does occur, the parts are readily replaceable, such parts requiring replacement being comparatively few in number and relatively inexpensive.

Nothwithstanding the foregoing advantages in this prior bore hole air hammer, wearing in, fit, and service problems can be encountered under the conditions of use of such apparatus, if the field operator is careless. In addition, the self-energizing clutch-like characteristic of the drive mechanism makes it difficult, requiring very high torque to break out the threaded connection between the drive sub and the housing.

SUMMARY OF THE INVENTION The present invention provides a rotary bore hole air hammer with a drive mechanism which has the advan-' tages of the air hammer of the aforesaid pending application, but which has further advantages in terms of manufacturing tolerances,simplicity of service and repair, as well as operation.

More particularly, the present invention provides a rotary bore hole air hammer having a drive mechanism which retains the torque transmitting characteristics of a splined connection while utilizing loose drive segments, but wherein the housing is not subjected to internal damage, such as gelling, and the drive sub is eas ily removed from the housing, since the drive segments and the companion recesses are soconstructed that high radial reaction forces are not generated during use or disassembly of the apparatus.

In accomplishing the foregoing, a driver and key structure is utilized wherein torque is transmitted through the keys, to the anvil, from the housing through near radial or slightly off radial, i.e., substantially radially extended surfaces, such that the forces transmitted do not tend to cam the segments outwardly.

In a specific form the segment and anvil surfaces are arranged so as to not apply a cam action to the segments in either direction, the surfaces being perpendicuular to the tangent of the anvil and housing. In this form the substantially radial surfaces are, thus, not truly radial but are parallel to one another and to a radial plane which is slightly off-set, to one side of the median plane of the segment to provide a larger contact area in the direction of drive when drilling than when the apparatus is being disassembled.

This invention possesses many other advantages and has other objects which may be made more clearly apparent from a consideration of a form in which it may be embodied. Such a form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense.

Referring to the. drawings:

FIGS. 1a and lb together constitute a longitudinal section through an apparatus embodying the invention, with parts in their relative positions in which the hammer piston has completed delivering an impact blow against its companion anvil and the drill bit secured thereto, FIG. lb being a lower continuation of FIG. 1a;

FIG. 2 is a cross-section taken along the line 22 on FIG. lb;

FIG. 3 is a longitudinal, fragmentary section taken along the line 3-3 on FIG. 2; and

FIG. 4 is an isometric view of one of the drive segments.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in the drawings an air hammer apparatus A is provided that is secured to the lower end of a string of drill pipe B, by means of which the apparatus is rotated to correspondingly rotate an impact anvil bit C used for drilling a bore hole D, the apparatus delivering repeated impact blows upon the anvil bit when compressed air is forced down the drill pipe for actuating the apparatus and for cleaning the cuttings from the bottom E of the hole. The apparatus is relatively simple, consisting of an elongate housing structure that includes an upper sub 11 having an upper threaded box 12 (or threaded pin, not shown) for threaded attachment to the lower end 13 of the string of drill pipe, that extends to the drilling rig (not shown) at the top of the bore hole D. This sub is threadedly secured to the upper portion of an elongate housing section 14, which can be of one piece, the lower end of which is threadedly secured to a lower housing head or drive member 15, the lower end 16 of the housing section bearing against an upwardly shoulder 17 formed on the head.

An elongate anvil portion 18 of the anvil bit C is piloted upwardly within the drive member and lower portion 19 of the housing section 14, a hammer piston 20 being reciprocable in the housing section above the anvil 18 to deliver repeated impact blows thereagainst. The anvil is preferably formed integrally with the drill bit portion 21 of the anvil bit, and which has suitable cutting elements 22 (such as sintered carbide buttons, not shown) mounted in its drilling face 23 for impacting against the bottom E ofthe bore hole, to produce cuttings therein, the cutting elements 22 also acting against the side of the bore hole adjacent to its bottom to insure the production of a bore hole D of the desired diameter.

During the reciprocation of the hammer piston 20 in the housing to deliver impact blows upon the anvil bit, the drill pipe string B and housing structure 10 are rotated at a desired speed, such as 20 r.p.m., to correspondingly rotate the anvil bit C and insure an impacting action of the cutting members 22 over substantially the entire cross-sectional area of the bottom E of the hole. During the impacting action, suitable drilling weight is imposed on the anvil bit through the drill pipe string B and the housing structure 10, such drilling weight being transferred from the lower end 24 of the housing head or drive member 15 to an upwardly facing shoulder 25 of the bit 21. The rotary drive itself is transferred from the housing structure 10 to the anvil 18 through a slidable spline type of connection 26, which is made in accordance with the invention and will be later described.

In general, the upper portion of the anvil has circumferentially spaced elongate recesses, in which drive segments 28 are disposed, these segments being carried in circumferentially spaced windows 29 in the drive member 15. The recesses 27 are substantially longer than the length of the segments 28, permitting relative longitudinal movement of the anvil bit C with respect to the housing structure 10. The rotary effort is transferred from the housing section 14 to the drive member 15 by virtue of the threaded connection 30d, and from the sides 29a of the openings or windows 29 to the segments 28, from where the turning effort is transmitted through the abutting segment surfaces 27a on the segments 28 and anvil surfaces 27 to the anvil 18 of the bit C.

The housing section 14 includes an elongate upper inner cylindrical housing wall 30, the lower end 31 of which constitutes an upper housing flow control corner at the upper end of an elongate internal circumferential exhaust groove 32 of a substantially larger internal diameter than the diameter of the inner cylindrical housing wall 34, which may be of the same internal diameter as the upper housing wall 30, the upper end of the lower wall being the housing lower flow control corner 33. The lower end 35 of the lower inner cylindrical housing wall 34 provides a by-pass corner at the upper end of an enlarged internal diameter circumferential by-pass groove 36.

The elongate hammer piston 20 includes an upper piston portion 37 having an external diameter 37a conforming to the diameter of the upper inner cylindrical housing wall 30, this upper piston portion terminating at the upper end 38 of an external circumferential exhaust groove 39 of a lesser external diameter than the upper piston portion 37. This external exhaust groove terminates at a lower piston portion 40 having an external diameter conforming to the internal diameter of the lower inner cylindrical housing wall 34. Below its lower piston portion 40, the hammer is of a reduced external diameter 41, providing a downwardly facing shoulder 42 which may, upon removal of the anvil bit C from the housing 10, engage a limit ring 43 mounted in the housing section 14, to prevent the piston 20 from inadvertently dropping out of the housing structure. The hammer piston extends upwardly to a substantial distance above its upper piston portion 37, having a plurality of circumferentially spaced relief spaces 44 which may be formed by elongate chords 45 in the hammer portion extending from the upper piston portion 37 to the upper end 46 of the latter, there being circumferentially spaced elongate arcuate sections 47 between the chords 45 having the same external diameter as the upper piston portion 37 and assisting in guiding the hammer piston 20 in its reciprocation within the housing section 14.

When the hammer piston 20 is at the lower end of its stroke, as shown in FIGS. 1a, 1b, a flow control piston corner 50 at the upper end of the piston portion 37 is spaced below the upper housing flow control corner 31, allowing air in the housing above the piston 20 to flow down through the passage 44 and into the internal circumferential exhaust groove 32, around the upper piston portion 37, then into radial exhaust ports 51, formed through the hammer piston below its intermediate piston wall 52, that communicate with an elongate central piston cavity 53 into which an exhaust tube 54 extends upwardly from the anvil 18, the tube forming a continuation of the exhaust passage 53 and communicating with an exhaust passage 55 through the anvil and through one or a plurality of exhaust passages 56 extending downwardly through the bit 21 and opening outwardly thereof for the purpose of enabling the drilling fluid to flow into the bore hole D for removing the cuttings from the bottom E of the hole. The tube 54 makes a slidable seal with the wall 53a of the piston cavity 53, being secured to the anvil 18 by a lower outwardly extending tube flange 57 being received within an inner circumferential groove 58 in the anvil. The tube may be made of an elastic material, such as Delrin, which permits it to be inserted within the anvil passage, the flange 57 contracting sufficientlyuntil it is opposite the circumferential groove 58, whereupon the tube flange can snap outwardly into the groove 58 and thereby lock the tube 54 to the anvil 18.

When the piston 20 is shifted upwardly within the housing on its return stroke, the return air corner 60 at the lower end of the lower piston portion 40 will be disposed above the housing lower flow control corner 33, whereupon the compressed air below the piston can exhaust into the internal circumferential housing groove 32 and flow through the exhaust ports 51 and exhaust passages 53, 55, 56 to the bottom E of the bore hole. At this time, the upper flow control piston corner 50 will be disposed above the upper housing flow control corner 31, which will seal the upper piston portion 37 against the upper inner cylindrical housing wall 30, whereupon compressed air can drive the piston 20 downwardly on its hammer or power stroke. When the return air corner 60 moves below the housing lower flow control corner 33, the air below the piston and within the housing, which remains after the lower piston portion 40 is closed within the lower end of the cylindrical housing wall 34, is subject to compression, but such air will be at a relatively low pressure.

In the event the apparatus is elevated to raise the bit 21 from the bottom E of the hole, as shown in the aforementioned apparatus, the bit will drop downwardly until its upper anvil head flange 110 engages the upper ends of the segments or keys 28; This will allow the upper piston by-pass corner 62 to shift below the housing by-pass corner 35 at the lower end of the lower inner cylindrical housing wall 34, the upper flow control piston corner being well below the upper housing flow control corner. Accordingly, compressed air above the piston can flow through the passages 44 and the internal circumferential exhaust groove 32 into the air by-pass groove 36 below the lower housing wall 34, the air passing downwardly through the passages 63 in the upper portion of the anvil rotary drive member and into the by-pass passages 64 past a head sealing portion 66 within the drivemember 15 and into elongate relief grooves 67 extending downwardly through the lower end of the drive member 15. When the anvil 18 is in its upper position within the housing and with the bit shoulder 25 engaging the lower end 24 of the drive member 15, the head sealing portion 66 seals against the periphery 68 of the anvil below its elongate grooves 27 in which the segments or keys 28 are positioned. To facilitate such sealing, the head portion 66 may have a plurality of longitudinally spaced internal labyrinth seal grooves 69 formed therein.

Compressed air for reciprocating the hammer piston passes downwardly through the string of drill pipe B and into the upper housing sub 11, flowing past a downwardly opening check valve 70 which may be in the form of a ball 71 received within a valve body 72 mounted in a counterbore 73 in the sub, the ball being movable upwardly to engage a companion seat 74 surrounding a central passage 75 through the body, the downward movement of the ball being limited by its engagement with circumferentially spaced feet 76 extending inwardly fron the body. With air being pumped downwardly through the apparatus, the ball7l engages the feet 76 and the air can flow around the ball and between the feet and into a central passage 77 in the housing sub.

The inlet air under pressure is caused to flow alternately into the housing below the piston 20 and the housing above the piston, to effect reciprocation of the hammer piston. A housing inlet and valve tube 78 are mounted in the sub passage 77, projecting downwardly from the sub or head 11 and into an upper elongate central piston cavity or chamber 79 above the intermediate piston wall 52, which separates the upper chamber 79 from the lower chamber 53. The tube 78 is secured in the sub by an upper external flange 80 on the tube fitting within a companion internal circumferential groove 81 in the sub. The inlet tube is made of a flexible material, such as. Delrin, which permits the upper portion of the tube to be deflected inwardly of the sub passage 77 below the circumferential groove 81, and when the flange becomes aligned with the groove, the latter inherently expands outwardly into the groove to secure the tube to the sub 11. The elastic nature of the tube is such that it also provides a slidable seal with the inner walls of the piston 20, as explained hereinbelow.

The piston has an elongate upper cylindrical surface 82 opening through its upper end 46 and terminating at an inner, upper flow control piston corner 83, which is the upper end portion of an elongate internal circumferential impact passage groove 84 having a substantially larger internal diameter than the inside diameter of the upper piston portion 82. The circumferential impact passage groove 84 terminates at an intermediate inner cylindrical piston wall 85, which may have the same internal diameter as the upper cylindrical piston wall 82, the intermediate wall terminating at an internal circumferential return passage groove 86 formed in the piston and terminating at a lower flow control piston corner 87, which is the upper end of a lower internal piston seal wall portion 88 that forms a bore extending between the intermediate pistion wall 52 and the corner 87. The inlet tube 78 has an upper external cylindrical sealing surface 89 relatively slidably sealable with the upper piston wall 82 and terminating in an external circumferential inlet groove 90 communicating with radial inlet ports 91 that open to the central inlet passage 92 through the tube. Below this circumferential inlet groove 90, the tube is formed with an intermediate cylindrical sealing surface section 93 slidably and sealingly engageable with the intermediate inner cylindrical piston wall and also with the lower piston wall 88.

When the piston 20 is in its lowermost operative position, with the drill bit 21 pressed against the bottom E of the bore hole D, compressed air can flow downwardly through the inlet passage 92, discharging into the circumferential return passage 86 that communicates with the upper portion of one or more longitudinal return passages 95 extending downwardly through the hammer piston and opening outwardly through its lower end 96. When the hammer piston 20 moves upwardly within the housing 10 and along the inlet tube 78, the lower flow control piston corner 87 shifts upwardly over the lower flow control housing tube corner 93a to interrupt communication between the inlet passage 92 and the return passages 95, continued upward movement of the piston then placing the inner upper flow control piston corner 83 above the upper flow control housing tube corner 98, which then allows compressed air to flow from the inlet passage 92 through the ports 91 into the circumferential inlet groove into the internal circumferential impact passage groove 84 and thence in the housing above the upper end 46 of the piston. At this time, the upper piston portion 50 will have moved partially above the upper housing flow control corner 31, so that the air under pressure between the upper end 46 of the piston and the housing sub or head 11 can act downwardly on the piston, urging it in a downward direction.

The piston 20 will be shifted downwardly until the upper flow control piston corner 83 moves below the flow control housing tube corner 98, which shuts off air driven against the upper face 100 of the anvil to deliver an impact blow to the impact bit C. As the piston nears the end of its downward stroke, the lower flow control piston corner 87 will move below the lower flow control housing tube corner 93a, thereby allowing the compressed air to flow from the inlet passage 92 into the upper piston cavity 79 and internal circumferential return passage groove 86, passing downwardly through the longitudinal return passages 95 to the lower end of the piston, such air then moving the piston in an upward direction, until the lower flow control piston corner 87 passes upwardly beyond the lower flow control housing tube corner 93a, once again, to shut off the flow of air into the return passages 95. When this occurs, the outer upper flow control piston corner 50 moves above the upper housing flow control corner 31 to shut off the exhaust of air from the housing region above the piston 20, the compressed air below the piston expanding and driving the hammer piston upwardly toward the head 11 of the housing. Before reaching the head 11, the inner upper flow control piston corner 83 will have shifted upwardly along the tube 78 to a position above the upper flow control housing tube corner 98, allowing air under pressure to pass from the inlet passage 92 through the impact passage grooves 90, 84 to a position in the housing above the piston 20.

The upward travel of the piston is cushioned by the compression of the air remaining in the housing above the piston. However, the pistion will still move upwardly sufficiently to place the lower corner 60 of the lower piston portion 40 above the housing lower flow control corner 33, which then permits the compressed air below the piston to travel into the internal circumferential exhaust groove 32 and through the exhaust ports 51 into the exhaust passages 53, 55, 56 for discharge from the drill bit. The compressed air in the housing structure above the piston then expands to drive the piston downwardly, and the foregoing cycle of operating is repeated, the piston reciprocating to deliver repeated impact blows against the anvil portion 18 of the anvil bit C, while the drill string B and the entire apparatus A is being rotated, to insure that the drilling or cutting elements 22 will cover substantially the entire cross-sectional area of the bore hole bottom E.

When it is desired to pump compressed air through the apparatus while the drill bit 21 is off bottom, elevation of the apparatus A will cause the impact bit C to drop downwardly along the housing until the upper anvil head 110 engages the upper ends of the keys 28. The piston 20 will also drop downwardly until its bypass corner 62 is below the by-pass corner 35 of the housing 10, the upper corner 62 of the piston being disposed below the upper end of the internal circumferential groove 36. Accordingly, compressed air flowing downwardly through the drill string B and into the inlet passage 92 can pass through the inlet ports 91 and upwardly between the tubing and the upper seal portion 82 to a position above the piston, then flowing downwardly through the passages 44 and into the internal circumferential exhaust groove 32, flowing between the external circumferential exhaust groove 39 in the piston and the opposed lower inner cylindrical housing wall 34 into the enlarged diameter groove 36 below the inner cylindrical housing wall, then passing through the passages 63, 64, 67 to the exterior of the bit 21. Since the path just described is open, compressed air cannot remain below the piston 20, which might otherwise tend to cause the piston to continue reciprocating andcyling in the housing 10. It is also evident that the compressed air being pumped through the apparatus will also flow through the exhaust ports 51 and the exhaust 53, 55, 56 and downwardly through the anvil bit C.

When the piston 20 is on its power stroke. air will be compressed below the piston, as pointed out above, because of the sealing of the lower piston portion 40 against the lower inner cylindrical housing wall 34 and the sealing of the head portion 66 against the periphery of the anvil 18. However, air under pressure is always present within the upper central piston cavity or chamber 79, acting over the cross-sectional area W of such chamber, and continuing to exert its force to overcome the pressure acting upwardly over the piston and tending to elevate it. Thus, the hammer piston 20 will strike its impact blow upon the upper end of the anvil with a greater force, in view of the overcoming ofa portion of the resisting force offered by the compressed air acting upwardly over the cross-sectional area R across the lower portion of the piston, such area existing between the periphery of the exhaust tube 54 and the lower inner cylindrical housing wall 34.

On its power stroke, the compressed air acts over the full cross-sectional area S of the upper piston portion, which is the same area as the area across the inner cylindrical housing wall 30. It is acting downwardly over the cross-sectional area of the piston between the pe riphery of the upper flow control tubeand the upper inner cylindrical housing wall 30, and also over the area W across the central piston cavity or chamber 79 During the return stroke, the compressed air is acting upwardly over the piston over the area R, which is less than the full cross-sectional area S, but such full area is not needed for the purpose of returning the piston under comparatively little load toward the upper end of its stroke.

As described above, the exhaust tube or sleeve 54 is made of an elastic material, which is a suitable synthetic resin such as Delrin. This sleeve must make a slidable seal with the wall 53a .of the piston cavity 53 to prevent or minimize leakage of air between the tube and the wall 53a. Because of manufacturing tolerances, a perfect alignment between the hammer piston 20 and the anvil 18 may not exist. Accordingly, as the piston approaches the anvil and impacts thereagainst, it imposes a lateral force on the exhaust sleeve 54. If the exhaust tube made a close fit with the wall 580 of the anvil downwardly from its upper face 100, even a small amount of misalignment between the piston 20 and the anvil would cause a high shearing stress to be imposed on the exhaust tube 54, resulting in fatigue failure of the exhaust tube after a relatively short period of use of the apparatus.

The above difficulty is overcome in the apparatus illustrated by providing relief between the exterior of the exhaust tube or sleeve 54 and the wall 580 of the anvil 18, such relief extending downwardly from the upper anvil face 100. As shown, a counterbore 58a is provided in the anvil that extends downwardly from its upper face 100 to a substantial extent, which, by way of example, is of the order of about l inch. In view of the counterbore, any misalignments between the piston and the anvil 18 will prevent the high stresses from occurring on the tube substantially in the plane of the upper face 100 of the anvil. Instead, the exhaust sleeve 54 can readily flex or bend about the base 58b of the counterbore, which acts as a fulcrum point, particularly in view of the elastic material from which the exhaust sleeve 54 is made. The bending stresses to which the tube 54 is subjected as a result of misalignment between the piston 20 and the anvil 18 are maintained at a comparatively low value, which prevents the exhaust sleeve 54 from fatigue failure.

As previously indicated, during drilling the drill pipe is rotated in a right hand direction, and such rotation is transmitted to the anvil bit 18 through the spline-like connection 26 between the drive member 15 and the anvil 18, through the drive segments 28 which are disposed in the anvil slots 27 .and the windows 29 in the drive member 15. The structural arrangement of the present drive connection is such that the rotary forces transmitted through the connection do not impose any outward camming action on the segments, in either direction of rotation, thereby minimizing wear and preventing galling of the segments or the housing. In addition, the structural arrangement of the drive connection is such that the contact area betweenthe segments and the anvil is maximized for strength in the direction of rotation during drilling. The segments also cooperate with the anvil to provide an air flow passage during circulation, as described above.

Referring to FIG. 2 it will be seen that in order to accomplish the above-noted advantages, in this illustrative form, the side walls 27a of the segments 28 and the opposed walls 27b of the groove 27 are disposed on planes which are substantially radial, though actually off radial, being parallel, and perpendicular to the tangent 18 of the anvil l8, and the walls 290 of the window 29 of the driver portion 15 of the housing are also parallel and coplanar with the slot walls 2712. Thus, no radial force component is applied to the segments 28 forcing them outwardly into binding engagement with the cylindrical inner wall of the housing 16. Indeed, the angle L between the confronting walls 27b, 29a and 27a and a true radial plane R1 is such that the segments are inherently forced inwardly by the torque transmitted therethrough.

In addition, in order to provide an increased section of the anvil 18 for transmitting torque while drilling, the center line of the segments 28 and the slot 27 are parallel to the radius R2 but offset in a direction opposite to the direction of drilling rotation, as indicated by the arrow D, so that the wall 27b opposing the direction of drilling rotation is wider than the other wall 27b. This latter wall 27b need only take the force transmitted in the direction of the arrow BO when the bit anvil 18 is held stationary and the housing 10 rotated to the left to break out the thread 30d which connects the housing 16 and the driver 15.

I claim:

1. ln hammer drilling apparatus comprising: a housing structure connectible to a drill string and including a housing section and a drive member detachably secured to and surrounded by said housing section; an

anvil in the housing structure; a' piston reciprocable in said housing structure for intermittently impacting against said anvil; said anvil having a plurality of circumferentially spaced, longitudinal recesses formed by side walls disposed on generally radial opposed planes; said drive member having circumferentially spaced openings therein extending completely through said drive member, said openings also being formed by side walls disposed on generally radially opposed planes; drive segments in said recesses and openings and having side walls engaged by said walls of said anvil and said drive member; said housing section surrounding said drive member, openings and segments to close said openings, said housing section engaging said segments to retain said segments in said recesses and openings.

2. In apparatusas defined in claim I; said anvil recesses being longer than said segments to enable said anvil to shift longitudinally in said housing structure and along said segments.

3. In apparatus as defined in claim 1; said segments being uniformly spaced from each other circumferentially of said housing structure.

4. In hammer drilling apparatus comprising: a housing structure connectible to a drill string; an anvil in the housing structure; a piston reciprocable in said housing structure for intermittently impacting against said anvil; drive means for transmitting rotary motion from said housing structure to said anvil including a drive segment interposed between said anvil and said hous ing, and generally radially projecting walls on said segment, on said anvil and on said housing for transmitting torque between said anvil and said housing withoutv forcing said segment outwardly into engagement with said housing; a plurality of said drive means uniformly spaced from each other circumferentially of said housing structure, each of said segments being on a center line spaced from and parallel to a radial plane of said anvil.

5. In hammer drilling apparatus comprising: a housing structure connectible to a drill string; an anvil in the housing structure; a piston reciprocable in said housing structure for intermittently impacting against said anvil; drive means for transmitting rotary motion from said housing structure to said anvil including a drive segment interposed between said anvil and said housing, and generally radially projecting walls on said segment, on said anvil and on said housing for transmitting torque between said anvil and said housing without forcing said segment outwardly into engagement with said housing; said segment having an air passage extending longitudinally therethrough.

6. In apparatus as defined in claim 1; said walls being disposed on parallel planes perpendicular to a tangent of said anvil.

' 7. In apparatus as defined in claim 4; said walls being disposed on parallel planes perpendicular to a tangent of said anvil.

8. In rotary hammer drilling apparatus: a housing structure connectible to a drill string and including a housing section and a drive member detachably secured to and surrounded by said housing section; an anvil bit shiftable axially in said housing structure; a hammer piston reciprocable in said housing structure for intermittently impacting upon the upper portion of said anvil bit; said anvil bit having a plurality of circumferentially spaced longitudinally extended recesses formed by side walls disposed on generally radial opposed planes; said drive member having circumferentially spaced openings therein extending completely through said drive member, said openings also being formed by side walls disposed on said generally radial opposed planes; drive segments in said recess and openings and having side walls engaged by said walls of said anvil bit and said drive member; said housing section surrounding said drive member, openings and segments to close said openings, said housing section engageing said segments to retain said segments in said recesses and openings.

9. In apparatus as defined in claim 8; the lower end of said drive member engaging said anvil bit to transmit drilling weight thereto; seal means between said anvil bit and drive member to prevent fluid leakage therebetween when the lower end of said drive member engages said anvil bit; means providing a fluid by-pass between said anvil bit and drive member upon elevation of said drive member with respectto said anvil bit; said by pass including said recesses in said anvil bit; and said segments having a longitudinal passage therethrough.

10. In apparatus as defined in claim 8; said side walls of said recesses and said openings being on parallel planes perpendicular to the tangent of said anvil bit.

11. In rotary hammer drilling apparatus: a housing structure connectible to a drill string and including a drive member detachably secured to a housing section; an anvil bit shiftable axially in said housing structure; a hammer piston reciprocable in said housing structure for intermittently impacting upon the upper portion of said anvil bit; said anvil bit having a plurality of circumferentially spaced longitudinally extended recesses formed by side walls disposed on generally radial opposed planes; said drive member having circumferentially spaced openings therein also formed by side walls disposed on said generally radial opposed planes; and drive segments in said recesses and openings and having side walls engaged by said walls of said anvil bit and said drive member; said recesses and said openings having centers located in planes parallel to and offset from a radial plane of said anvil bit in a direction opposite to the direction of drilling rotation of the apparatus 12. In apparatus as defined in claim 11; said housing and said drive member having a threaded connection made up in the direction of drilling rotation of the apparatus.

13. In apparatus as defined in claim 11; said side walls of said recesses and said openings being on parallel planes perpendicular to the tangent of said anvil bit, said housing and said drive member having a threaded connection made up in the direction of drilling rotation of the apparatus.

14. In apparatus as defined in claim 11; said side walls of said recesses and said openings being on parallel planes perpendicular to the tangent of said anvil bit; said housing and said drive member having a threaded connection made up in the direction of drilling rotation of the apparatus; the lower end of said drive member engaging said anvil bit to transmit drilling weight thereto; seal means between said anvil bit and drive member to prevent fluid leakage therebetween when the lower end of said drive member engages said anvil bit; means providing a fluid by-pass between said anvil bit and drive member upon elevation of said drive member with respect to said anvil bit; said by-pass including said recesses in said anvil bit;'and said segments having a longitudinal passage therethrough.

15. In rotary hammer drilling apparatus: a housing structure connectible to a drill string and including a housing section and a drive member detachably secured to and surrounded by said housing section; an anvil bit shiftable axially in said housing structure; said anvil bit having a plurality of circumferentially spaced longitudinally extended recesses formed by side walls disposed on generally radial opposed planes; said drive member having circumferentially spaced openings therein extending completely through said drive member, said openings also being formed by side walls disposed on said generally radial opposed planes; drive segments in said recesses and openings and having side walls engaged by said walls of said anvil bit and said drive member; said housing section surrounding said drive member, openings and segments to close said openings, said housing action engaging said segments to retain said segments in said recesses and openings.

16. In rotary hammer drilling apparatus: a housing structure connectible to a drill string and including a drive member detachably secured to a housing section; an anvil bit shiftable axially in said housing structure; said anvil bit having a plurality of circumferentially spaced longitudinally extended recesses formed by side walls disposed on generally radial opposed planes; said drive member having circumferentially spaced openings therein also formed by side walls disposed on said generally radial opposed planes; and drive segments in said recesses and openings and having side walls engaged by said walls of said anvil bit and said drive member; the lower end of said drive member engaging said anvil bit to transmit drilling weight thereto; seal means between said anvil bit and drive member to prevent fluid leakage therebetween when the lower end of said drive member engages said anvil bit; means providing a fluid by-pass between said anvil bit and drive member upon elevation of said drive member with respect to said anvil bit; said by-pass including said recesses in said anvil bit; and said segments having a longitudinal passage therethrough.

17. In apparatus as defined in claim 15; said side walls of said recesses and said openings being on parallel planes perpendicular to the tangent of said anvil bit.

18. In rotary hammer drilling apparatus: a housing structure connectible to a drill string and including a drive member detachably secured to a housing section; an anvil bit shiftable axially in said housing structure; said anvil bit having a plurality of circumferentially spaced longitudinally extended recesses formed by side walls disposed on generally radial opposed planes; said drive' member having circumferentially spaced openings therein also formed by side walls disposed on said generally radial opposed planes; and drive segments in said recesses and openings and having side walls engaged by said walls of said anvil bit and said drive member; said recesses and said openings having centers located in planes parallel to and offset from a radial plane of said anvil bit in a direction opposite to the direction of drilling rotation of the apparatus.

19. In apparatus as defined in claim 18; said side walls of said recesses and said openings being on parallel planes perpendicular to the tangent of said anvil bit, said housing and said drive member having a threaded connection made up in the direction of drilling rotation of the apparatus.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3606930 *Oct 6, 1969Sep 21, 1971Baker Oil Tools IncDown-hole drilling hammer
US3612191 *Mar 11, 1970Oct 12, 1971Martini Leo AndrewPercussion drilling tool
US3630292 *Mar 9, 1970Dec 28, 1971Amoco Prod CoVibratory hammer drill
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4030554 *Jul 7, 1975Jun 21, 1977Bakerdrill, Inc.Bore hole airhammer and anvil bit
US4054180 *Feb 9, 1976Oct 18, 1977Reed Tool CompanyImpact drilling tool having a shuttle valve
US4530408 *Mar 28, 1983Jul 23, 1985Toutant Roland JPorting system for pneumatic impact hammer
US4702326 *Jun 7, 1985Oct 27, 1987Oy Tampella AbCoupling arrangement for a drill shank of a percussion drilling machine
US4805705 *Sep 8, 1987Feb 21, 1989Santrade LimitedDrill bit
US5038874 *Feb 5, 1990Aug 13, 1991Sandvik AbDrill bit having a flushing medium channel
US5263899 *Jun 7, 1990Nov 23, 1993Hitachi Construction Machinery Co., Ltd.Cylindrical telescopic kelly-bar apparatus
US6808455 *May 3, 2000Oct 26, 2004Michael SolorenkoTorsional shock absorber for a drill string
US6834889 *Dec 22, 2000Dec 28, 2004Den Norske Stats Oljesselskap A.S.Torque release coupling for use in drill strings
US7338051Nov 13, 2003Mar 4, 2008Black & Decker Inc.Tool holder for a rotary hammer
US7438140Jan 17, 2007Oct 21, 2008Exhaust Technologies, Inc.Shock attenuating device for a rotary impact tool
EP0003103A2 *Jan 2, 1979Jul 25, 1979Boart International LimitedDown-the-hole drill
EP0005384A1 *Mar 7, 1979Nov 14, 1979Stenuick Freres S.A.Down-hole air hammer comprising a drill bit
EP0461311A2 *Jun 12, 1990Dec 18, 1991Hitachi Construction Machinery Co., Ltd.Cylindrical telescopic kelly-bar apparatus
EP0798444A1 *Jun 12, 1990Oct 1, 1997Hitachi Construction Machinery Co., Ltd.Cylindrical telescopic kelly-bar apparatus
Classifications
U.S. Classification173/73, 173/131, 464/18, 173/78, 173/80
International ClassificationE21B17/02, E21B4/00, E21B4/14, E21B4/10, E21B17/07
Cooperative ClassificationE21B4/14, E21B17/07, E21B17/076
European ClassificationE21B17/07P, E21B4/14, E21B17/07
Legal Events
DateCodeEventDescription
Dec 18, 1981AS02Assignment of assignor's interest
Owner name: REED MINING TOOLS, INC., HOUSTON, TEX.
Effective date: 19800320
Owner name: REED TOOL COMPANY (DELAWARE)
Dec 18, 1981ASAssignment
Owner name: REED MINING TOOLS, INC., HOUSTON, TEX.
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:REED TOOL COMPANY (DELAWARE);REEL/FRAME:003936/0168
Effective date: 19800320