US2495364A - Means for controlling bit action - Google Patents

Description

Jan. 24, 1950 w.: H. CLAPP MEANS FOR- CQNTROLLING BIT ACTION Filed Jan. 27. 1945 5 3 gm m A PH MN IWQV v m .VM Z Crw5 a4y w bfi ww fifi my; .wm

Jan. 24, 1950 w. H. CLAPP MEANS FOR CONTROLLING BIT ACTION 2 Sheets-Sheet Filed Jan. 27. 1945 INVENTOP. MLL/A H CLAPP Haze/5, Mich; Fbsr i'f/nm/s Patented Jan. 24, 1950 J:

TZED S OFFICE S'FOR CONTROLIHNGQITACTION William-H.- Cla;pp, Pasadena,Calif. Application Ja'nflary27, 1945;-"seiia1"No:'574;835

- 5.1 "I his' zinven'tionrelates to'the art 'of rotary drill-- ing' with special"referenceito theart of drilling wells. The invention isdirected 'spe'cifically to a highly-novel means for acceleratingth'e rate o'f d'ril-lin'gby continuously controllin the action of the drilling bit by compounding percussive motion with rotary motion-wheneverdesirable. Manyattempts have beenqnadeto cause a rotating-bit to drill "-v vi thpercussion. The advantages of percussivearming; particularly 'in' hard strata, have long been appreciated, as evidenced by the continued 1 use iofl cable tool -meth'ods; Suchadvantages can occ'a'siona'lly bese'ciuredwith rotary drilling 'ejq'uipment if successive beds -'-of hard and soft strata ere-encountered by thebit, since the jet of drilling*rnud-ejecting'from'the rot'atingbit may Wash through a layer ofsand'or unconsolidated material and allow t'he-drilltd-faH upon 'theunderlying frock and bounce rh-ythmically during theoscillatory elongations of the elastic drill pipe. I

Occasionally 'such peroussive action can" beinitiatedby causing: the rotating bit' -to -'stick' momentarily, if the drill pipeis'lowered too rapi duringthis-n omento meme therotatin d pipe continues to"wind up;twistingint ra-lized'form which tends toshor ten the d and decrease the pressure of tlie b it uponthe bit-y stratum, thus tendingto free the stalldibitarid thus release-the torsional energystored 'in the stressed drill pipe. Thesubsequent percussion oi' the bit is actuated bythe oscillatory*elongations 0f the lasticdlill-Stem. The val-ueof theseartificial methods 'ofinducin'g oscillationis limited, of"

course, since drilling condit-ior isare'sel-dorn favo r* able. 'For example, 'theeifectiveness of "percussion would be greatest during the drilling-offs.

tough limestone shell, hard-shaleorot her relatively impervious orimpenetrablefstrata but-in thes cases oscillationnanihardly be induced.

The imperative. necessity of employing percus sion for such hard"rockdrilling may"beemphasized by directing attention to tnewli known fact that such difficultie's frequently encourage the crude practice of "actually elevating the-bit ten or twenty feet" off bottom? th'e'n'- dropping' the entirerapidly rotating drill-string" 'and attempting to interruptthisdescent'by meansof-thehand brake operated by the drillerfwhothus attempts to restrain the falling drill pipebeforedamage is incurred. Repetition oi this criide and arduous procedure increasestheobviously inherentriskof bending the drill pipe --a'nd overstressin'g 1 the threadedbonnections' in I count of such *dangerous practics; man 'at tempts have -beenmade motion of the bit into-a percussive motion.

' T-he-various devices advocated for this purpose have failed to receive-approval or general acceptanceinthe art eitheras airesuit of the -itnpracticability of theirdesignor "beeausethe intensity of the-peroussion thus -imparted"to-=a bit was relatively negligible. Such-prior devices 'have been particularly -unsatisfactory because their construction merely-provided continuous'weak percussionwithoutinoorporati-ng' any means for preventing percussion or controlling the intensity our-e maximums-percussive eifectby utilizing; the

expansion nf thexacompressed drill :pipe and the momentum of the falling drill collar-.to drive the I Another paramount purpose of the invention is toprovide a meansitoncontrolling bit percussion, suchwcontrolwbei-ng;operated by the driller.

:iThis:feature of'the'einvention guarantees posi-,

tive regulation of the intensity of percussion and therefore includesthe opportunity of employing discretion, aswellsaspercussive power, since such action may be utilized whenever highly 001150111,

dated or-tough strata-tare encountered; alternativelygsuchaction may be entirely eliminated in favor-of high. torque rotation whenever the driller 'so-:elects, 'e;s when soft or unconsolidated strata are penetrated. A major objective of the invention is to provide sin-automatic means fornot only. generating peroussi'oh but also for combimng' intensenperc'ussive action with high" torque rotary action and delivr-ing s'ii'ch 'eon'i'pou-nd action to thebit whenever the'drillersodesires. 2

' A fui ther purpose of the invention is tov provide for the regulation 0f the automatic means for generating percussion-by merely varying the bit pressure, "as indicatedby the weight indicator? and controlld bythe d l i lli. Another objective-ofthe-invention is to pre vent twist offs of -the drill 'st'emby providing an aiitomatic -'-=irleans for generating percussion *wnenever the torsional stres's in the 1on1; pipe -to transfo'rm the. rotary 3 reaches a predetermined maximum allowable workin load.

Another advantage sought by this invention is that of automatically regulating the bit torque by controlling the bit pressure.

By means of this invention I also propose to conserve the drilling time which is conventionally dissipated whenever a round trip is required in order to replace a drag bit or fish-tail bit with a rock bit or roller-cutter bit.

The achievement of the aforesaid objectives by creating a means whose structural rigidity and V indestructibility and simplicity afiords adequate i protection against failure, defines a principal purpose of the invention.

The structural principles which indicate the efficiency of the proposed means of controlling bit action also indicate that such efiiciency is substantially independent of the form and arrangement of certain auxiliary features. Therefore, although the following disclosure of the invention is illustrated by a specific embodiment, it should be clearly understood that such reference is merely intended as illustrative.

. Referring to the drawings, Fig. 1 is an elevational View of the drilling tools employed in conventional rotary drilling practice, including the bit, the drill pipe, the derrick fioor, the rotary table, the kelly, the swivel, the flexible mud hose connected to the slush pump and the traveling block supported by the drilling line{ or cable; the associated crown block and derrick structure are not shown.

Fig. 2 exemplifies a vertical section of the upper portion of the proposed means for controlling bit action.

Fig. 3 illustrates a longitudinal view, partly in section, of the lower portion of the proposed cone trolling means.

Fig. 4 shows a plan View of a transverse section taken along the line A-A of Fig. 3.

Figs. 5 and 6 delineate an alternative embodiment of the invention, Fig. 5 representing the upper portion and Fig. 6 representing the lower portion thereof.

Fig. '7 reveals a plan view of a transverse sec-,- tion taken along the line BB of Fig. 5.

Figs. 8a, 8'0, 80 and 8d represent schematic diagrams showing mutual displacement of camshaped projections, produced by relative rotation of a pair of cam rings.

Referring in detail to Fig. 1, the so-called drilling tools ID of a rotary drilling system are delineated diagrammatically. The bit-strae tum H is drilled by the action of a rotatable or percussible bit 2 which is conventionally rotated by a drill collar l3. However, the position of the proposed means 30 for controlling bit ac-v tion is exemplified as intermediate between the bit I2 and the drill collar IS. The latter is attached to, and actuated by, drill pipe I4, portions of which are shown within walls I5 and casing 16 which define the drill hole. The drill pipe l4 passes through a derrick floor I? and rotary table I8 and engages a kelly l9 which is supported by a swivel 2|, swivel bail 22, hook 23, traveling block 24 and drilling line or cable 25.- The conventional rotary drilling system 20 also includes a continuous circulation of drilling mud which is delivered to the interior of the drill stem |4 by flexible hose 26 and stand pipe 21 which connect a slush pump 28 to the swivel 2|, such drilling mud being ejected from the bit and then returned tothe surface through the annular spacebetween the drill pipe l4 and the walls l5 of the drill hole.

Fig. 2 illustrates the upper portion of the means" 30 for controlling the action of the bit I2. A tubular driving member 3| is attached to the lower end of the drill collar IE, or connected thereto by means of an intermediate coupling member or sub 32 threaded for this purpose. The driving member 3| actuates a driven member 5| which is threadedly connected to the bit |2 or to an intermediate coupling member or sub 52 which may be seen in Fig. 3. This driving member 3| actuates several associated elements which will be collectively designated as the driving assembly 40 since these components could be consolidated into a single driving unit, although many advantages of the preferred construction would be sacrificed thereby.

The driving member 3| is exemplified in Figs. 2 and 3 as a very strong steel sleeve formed with a relatively thicker wall in the central portion 3|--b than in the upper and lower portions 3|-a and 3|c, respectively, in order to provide inwarclly extending shoulders 33 and 34 therebetween. The lower end of the sleeve 3| is externally threaded for connection with an abutment member or special coupling 35 whose lower surface 35 is serrated or notched, preferably with square teeth, in order to engage a complementary surface 31 formed on the upper surface of a hardened steel ring or displacement member 38 whose lower surface is characterized by two or more equally spaced cam-shaped projections 39 having fiat ends or dwell surfaces 39-a and inclined sides 39-!) such projections being separated by engagement surfaces 39-0.

This cam ring-38 is adapted for releasable engagement with a corresponding element 58 which actuates several associated elements which will be collectively designated as the driven assembly 5|]. 7

The displacement member 58 is similar in form to the cam ring 38, although inverted with respect thereto, having an upper surface which is characteri'zed by two or more equally spaced camshaped projections 59 having flat ends or dwell surfaces 59--a and inclined sides 59-b, such projections being separated by engagement surfaces 59c. g

The driven member 5| is actuated by the cam ring 58, Whose lower surface 51 is notched, preferably being formed with square teeth in order to engage the complementar uppersurface 56 of an abutment member or special coupling 55 which is threadedly connected to a base 54 and also supported by a shoulder 53' of the driven member 5| The inner elements of the means 30 for controlling bit action are contained within an annular space 4| between the driving member 3| and the driven member 5|. The latter has a relatively stronger-base section 54 below a shoulder 53 where the diameter decreases to provide a larger annular-space and an outer surface 64 within a packing ring nut 42 which is threadedly connected to the inner surface of the abutment member 35.

This packing ring nut 42 compresses a packing spring 43, a retaining ring 44 and packing material 45 which seals the lowerend of the annular space 4| against the entrance of drilling mud. The packing material 45 is restrained by a pack-. ing ring 4'l which is immobilized by the lower surface of the inwardly extending shoulder 34 provided by the driving member 3| 5. "The compression of a coiled" spring or resilient means 60 provides aforce which compressesthe displacement means-38 I and '58 by urging the driving assembly'downwardly and driven assembly upwardly. This effect is secured" by com-1 pressing the coiled spring 60 I between av lower restraining ring 48 and an upper restraining ring 65, the former being supporting by the shoulder 33 and the latter being restrained by an antifriction bearing-'66 which bears against an adjustlng means or sleeve nut '61. This bearing 66 minimizes the torsional deformation of the coiled spring Enduring percussion.

. A packing member 49 seals the upper end of the annular space 4| against th'eentrance ofv drilling mud. The upper end of the packing member 49 is externally threaded for connection with the driving member "3i-a. An-inwardly extending shoulder ta supports packing mate'rial 49-h. which is compressed by a packingspring 49c:

restrained by an externall threaded packing-nut 49d. The latter is axially bored to provide a tubular surface 49-e. During relative rotation of the driving assembly 40 with respect to the driven assembly 50, mutual alignment of the driving member 31 and the driven member is maintained by close fitting bearing surfaces 64 and 68, the latter'being adjacent to the aforesaid tubular surface ls-e.

Fig. 4 indicates a plan view of a transverse lower end of the drill collar 13 or connected thereto by means of an intermediate coupling] member or sub 32' threaded for this purpose. The driving member 3! actuates a'driven member 5i which is threadedly connected to the bit' l2 or to an intermediate coupling'memberor sub 52. This driving member 3! 'actua'tes several associated elements which will be collectively designated as the driving assembly or driving unit 40 since these elements could be consolidatedinto a single driving member, although manyadvantages of the preferred construction would be-sacrified thereby. f

The driving member 3| is-exemplified in Figs.-

5 and 6 as a very strong steel sleeve formedwith a relatively thicker wall in the lower portion:

3] -b than in the upper portion 3 l 'a, in order to provide an inwardly extending shoulder 33' therebetween. The lower end of the sleeve 3| is. internally threadedfor connection with an abutment member or special coupling 35 whoselower-x surface 36 is serrated or notched, preferably with square teeth in order to engage a complementary surface 31 formed on the upper surface of a hardened steel ring or displacement member.

38' whose lower surface is characterized by two or more equally spaced cam-shaped projections 39 having flat ends ordwell surfaces -39-a and inclined sides 39b, such projections being separated by engagement surfaces 39c. This cam ring 38 is adaptedfor releasable? 6. engagement with a corresponding element .58" which actuatesseveral associatedelements which will be collectively designatedas the drivenias sembly or drivenzuniti The displacementrxmember 158' is :similar in formto the cam ring'38', although inverted with respect thereto, having an upper surface which is. characterized by-two or m'ore equally spaced cam-shaped projections '59 havingmflat ends or dwell surfaces 59'.a 'and inclined sides 59'b, such projections being-separated by engagement surfaces 59'--c. The driven member 5'! is actuated by the cam ring 58, whose lowersurface 51' is notched, preferably being formed with square teeth in order to engagethecomplementary upper surfaceriifi'mof anabutment member or special coupling 55 which is 'threadedly connected to the base 54' and also supported by the shoulderfit' of the driven member 5!.

The inner elements of the controlling means 30, vare-contained within-the annular space. 4|

between the driving'member 3l and the driven member 5!. The latter has a relatively stronger base section 54 below a shoulder563 above which the diameter decreases to provide a larger annular space and an outer surface 64" within arestraining ring-42" which is supported by the upper surface of an inwardlyexten'ding shoulder 34 of the drivingm'ember 3V.

means .fprovides -.a force which compresses the displacement means 38' and 58 by urging the driving assembly downwardly and thedrivenas sembly upwardly. This effect is'secured by compressing the coiled spring 60 between the lower restraining ring- 42' andvan upper restraining ring the former: being .supported by the shoulder 34' and the latter beingrestrained by an anti-friction ring 66" which bears against'an adjusting means orsleevenutfil'. This frictional drag of the thrust bearing .ring 56 increases the torsional moment applied .to the driven unit 50'.

The compression of-a secondcoiled springer resilient means 'lflprovides an additional force which a further compresses the displacement means 38' and =58' by urging thedriving assembly downwardly and the driven assembly Iupwardly. This effect issecured'by compressing the coiled and upper ring 12, the former being. supported by the shoulder 33' and the latter being restrained by an anti-friction ring 13 which bears against anadjusting meansor sleeve nut 14. This antifriction ring 13 minimizes the torsional deformation of the coiled spring 10 during percussion.

A packing member 49 seals the upper end of the annular space 4 I "against the entrance of the drilling-mud. The upper end of the packing member 49,. is externally threaded for connection with the driving gmember 3|'a. An inwardly extending shoulder-49'-a supports packing .material 4'9'--b which is compressedrby a packing spring 49-c restrained by a packing nut d9--d. The latter is axially'bored to'provide a tubular surface ,491.e.

.During Jrelative rotation of the driving unit 40' with respect to'the drivenunit. 5t, mutual alignment of the driving member 3|.and the driven'member 5|! ismaintained by close fitting bearing surfaces 64' and 68, the latter beingadi the adjusting.means orrsleevernut. .14 rthreadedly J The compression'of acoiled spring orresilient spring '10 between alower restraining ring H and connected to the tubular driven member and surrounded by the driving member 3i'a. The cylindrical bore 69' of the driven member 5| conducts the drilling mud therethrough.

The means 30 for controlling bit action may be employed for generating percussion, for controlling the intensity thereof and for controlling the maximum torque transmitted to the bit.

The maximum torque or disengagement torque which may be applied to the driven unit 50 by the driving unit 49 may be defined as the limiting value of torsional moment which may be sustained by the engagement of the cam rings 38 and 58 without causing them to disengage. Whenever this disengagement torque is exceeded by the driving torque, the upper cam ring 38 will be rotated upon, and with respect to, the lower cam ring 58.

This rotation will be impeded, of course, by the intermittent re-engagement of the projections 39 and 59, such periodical rte-engagement being caused by the compression of the cam rings between the driving unit 40 and the driven unit 59. This compression is equal to the force supplied by the compressed spring 60 and the reactionary force exerted by the bit-stratum in responsive opposition to the bit pressure diminished by the weight of the bit I2, the bit-sub 52, and the driven member 5i. Consequently, the aforesaid disengagement torque is a variable quantity which may be increased by increasing the bit pressure and by increasing the spring compression. Hence,

whenever the driving torque exceeds the disengagement torque transmitted to the driven unit, the upper cam will be rotated upon the lower cam and thus periodically displaced therefrom as the projections 39 encounter and slide over the projections 59, i. e., the bit will percuss. Therefore, the bit torque is equal to the disengagement torque as long as the bit percusses.

In order to provide a complete disclosure of the principles involved in the invention, a detailed consideration of the successive phases of a single percussion cycle is desirable.

The first phase of the percussion cycle begins when the cam rings 38 and 58 occupy the relative positions illustrated in Fig. 8a. During this first phase, the inclined surfaces 39--b slide upwardly along the inclined surfaces 59 b, thus displacing the cam rings to the position shown in Fig 8b. The interval of time elapsing during this displacement may be designated as the displacement time.

During this primary interval, the mutual displacement of the concentric cam rings 38 and 58 increases the bit pressure and thus increases the reactionary torque exerted by the bit-stratum in responsive opposition to the increased torsional moment of the bit. Such vertical displacement of the concentric cam rings also raises the driving member 3!, elevates the drill-collar l3 and increases the compressional and torsional energy accumulated in the twisted drill-stem.

The secondary phase of the percussion cycle defines an interval of traverse time which elapses while the dwell surfaces 39-0. slide along the dwell surfaces 59a, a substantial wearing surface being provided therefor.

The interval of time elapsing during these primary and secondary phases of the percussion cycle is substantially greater than the subsequent interval of closure time, a third interval which elapses while the vertically displaced cams become re-engaged, i. e., while projections '59 move Vertically toward the engagement surfaces 39-c 8v between projections 39. At the instant of cam release the bottom of the spring 60 starts to move downwardly since it is anchored to the falling driving member 3!. At the same instant the 1 restraint on the spring 50 imposed by the cams is removed and the spring expands abruptly, thus jerking the bit off bottom before bringing the cams into their original closure.

During the fourth phase of the percussion cycle, the projections 39 rotate toward the projections 59, without causing any relative vertical displacement of the cam rings.

This is the interval of impact time. The drill collar has been displaced upwardly, energy of compression and torsion has been accumulated in the drill pipe, the bit has been jerked oif bottom with an upward acceleration several times greater than the downward acceleration of the ponderous drill collar, a prerequisite which is fulfilled by employing sufficient strength, stiffness or incompressability in springs 69 and 10 to provide an upward force several times greater than the combined weight of the driven unit, bit and bit sub. This important prerequisite guarantees a greater upward acceleration of the driven unit than the simultaneous downward acceleration of the falling drill collar.

This is the situation at the beginning of the interval of impact time. The cam rings are compressed. The bit is rotating more slowly than the drill collar because projections 39 are rotating toward projections 59. Angular acceleration is being imparted to the bit. Vertical acceleration is being imparted to the bit. Nothing impedes the descending bit. Therefore, the compressed drill pipe and the heavy descending mass of the drill collar drive the rotating bit into the bitstratum with a percussion blow which is intense.

This intense impact must occur before the end of the fourth phase of the percussion cycle, i. e., before the cam rings reach the position shown in Fig. 8a, since the horizontal portions of the cam rings must be in contact at the instant of impact. For this important reason, only four cam projections 39 and 59 are illustrated in the drawings. Fewer projections assure the fulfillment of this requirement, since the duration of the fourth phase of the percussion cycle is increased thereby.

The foregoing sequence of events is repeated every time the projections 39 traverse the projections 59. Continuous percussion with high torque is thus achieved. The intensity of this available bit torque will be determined by and will increase with, the angle of inclination of the sloping sides 39-b and 59-h of the projections 39 and 59, by the compression of the cams and therefore by the bit pressure. The latter is controlled by the driller and measured by the weight indicator." The bit pressure is not limited, therefore, except to such values as have previously been considered low enough to assure a substantially straight drill hole and low enough to prevent twisting off the drill pipe. Hence the maximum bit torque, available during percussive drilling has not been decreased by incorporating the control means 30 into the drilling tools l9, since the maximum bit torque is equal to the maximum disengagement torque as determined by the maximum permissible bit pressure.

Bit percussion will be prevented by decreasing the bit pressure and thus decreasing the bit torque. Since the latter was equal to the disengagement torque during percussion and since it has now been decreased, the bit torque must the radius of the cam rings.-

.39'-b and 59.b of the cam projections, or by increasing the radius of the cam rings, or by increasing the bit pressure.-

have become smaller"- than the disengagement torque; therefore, thebit'will not percuss.

The available bit torque during non-percussive drilling may be-increased with the bit pressure until it becomes equal to the disengagement {o5 highly consolidated-strata are encountered.

torque. The availablebittorque may then be further increased with the bitpressure, during percussive drilling, while the disengagement torque increases and causes the torsional stress Such positive regulation of the intensity of percussion enables the driller to employ discretion, sincepercussive action may be utilized by increasing the bit pressure whenever tough or This bit pressure control allows the driller to act in accordance with conventional practice, since percussion may be eliminated in favor of high-torque rotation whenever this is considered to approach the maximum allowable torsionalf' lifl preferable.

stress of the drill pipe. Consequently, the drill pipe can be protected against excess torsional stress by designing the control means -30 with a maximum disengagement torque which is less This invention utilizes a completely new principle in the art of drilling and discloses a-method of controlling the action ofthe bit. Various uncontrollable contrivances have been proposed,

than the maximum allowable torsional stress ofq heretofore, wherebya weak'impulse was delivered the drill pipe. This design requirement indicates an upper limit for-the combined strength of "the springs 60' and T0 for the slope of the sides 39--b and 59b of the cam ring-projections and for Hence, the use of both of the springs '60" and H'I'is more important if the control *meansis to 'be used with small drill pipe.

The available bit torque-, during non-percussive drilling or percussive-drilling may be increased, therefore, by increasing the compression increasing the angle of inclination of the sides The character of the bit-stratum will also determine the bittorque, since sticky or unconsolidated .form-ations will'tend to prevent the rotation of the bit and therefore tend tov increase the bit torque. This drilling condition-has been characterized, heretofore, by the maximum danger'of twisting off the drill pipe; Such'conventional risks are eliminated by my invention, because, whenever soft or sticky formations are drilled I'the optimum bit pressure is relatively low; hence the disengagement torque isrelatively low; consequently, if the'increased bit torque'is excessive, it will become equal to the disengagement torque and the bit-will therefore percuss, thus relieving the excesstorsional stress in the drill pipe.

These considerations may be expressed more explicitly by means of the mathematical relationship between these variables.

The intensity of percussion may be increased by increasing the bit-pressure; by increasing the compression of the cam rings, byincreasing the com pression of the'spring- 60, by increasing the angle of inclination ofthe sides39-b and 59'b of thecam projections, or byemploying an additional resilient means III as exemplified" in Figs. 5 and'6.

A paramount feature of 'this invention is the mechan cal design of the control means'30, whose simplicity allows structural rigidity, as exemplified by the indestructability of'the few heavy moving parts. Furthermore, the design provides for continuous cooling of the cam rings-by the circulating drilling mud. These meritorius considerations guarantee positiveaction and durable "service.

The designof the controi'rneans'30is-unique.

Terrific impact' may be delivered by a rotating bit by employing this automatic means for com' -pletely disengaging the bit andliiting both the: bit and the drillcollar'beforeallowing' the falling drill collar to drive the-rotating bit intothe bitstratum. The-intensity of-this impact-may be '?controlled by thedrillerby-regulating. the bit'pres- :Sura.

to the bit and thus partially transmitted to the bit-stratum. The eiiectiveness of such prior methods has been. destroyed by the inertia of the bit, since the impulse absorbed by the bit was .12 not necessarily transmitted to the bit-stratum;

instead, most of the'impact energy wasdissipated by vibrating ordeforming the bit, rather than the bit-stratum;

My invention guarantees the delivery of all of g5-ythe impact energy tothe bit-stratumby accumulating potential energy in the bit, in the control means and in the drill collar during the elevation of these members by an ingenious:automaticcontrol means which suddenly releases all of this go-potential energy by allowing these members to fall upon the bit-stratum.-

This fundamental principle of drilling with a falling bit and drill collar necessitates the use of sufiicient spring force to accelerate the hit up- :w-ardly at a rate-which exceedsthe downward ac- --cele-ration of the falling drill collar, since this requirement guarantees that. the bit'will belifted ofi bottom before the percussion blow. In order -to-utilize-th-is principle effectively it is preferable -10 =-to design the engagement surfaces 39-0 and 59'-c substantially longer than the dwell sur- -faces 39aand '59-a, an expedient which pro- ;vides for the relative rotation. of these surfaces during-the .impact interval of the percussion cycle; This consideration guarantees that these surfaces will be engaged. at the instant of'impact.

The various objectives oflthe inventionhave been achieved..- Intense percussive action has been combined with high-torque rotation. Such compound action maybe generated and controlled .whenever desired. Such regulation is visibly evidenced by thefweight indicator.

Protection against twisting-off the drill stem 155 is provided by an automatic means for generat- .ing percussion whenever. the" torsional stress therein reaches a redetermined maximum allowable working stress.

The preferred form of my invention described .ifiO'f herein in specific detail for the purpose of disclosure and to illustrate theprinciples involved, will suggest to those skilled in the art various changes; modificationsand substitutions that do not depart from my-underlying concept, I reserve-the right'to all such changes, mod fications and substitutions that-pro erly come within the 'scope' of my appended 'claims;

I claim as my invention: i 3 1. A combination of parts for use in the'rotary ?.0 {system of drilling wells, which comprises:. a drill pipe" extending from the bit assembly and upwardly through the well to a point above the top i of the"well bore; means above the top of. the w'ell bore 'jforiotating the. drill pipe; means for fl -supponting galLbr partsof theweight of thedrill pipe; an upper displacement member having an upper interrupted cam on the lower end thereof;

: means rigidly connecting the upper displacement member to the drill pipe; a lower displacement member having a lower interrupted cam on the upper end thereof, said upper and lower cams being in contact with each other when the bit is in firm contact with the bottom of the well and being so formed that when the upper displacement member rotates at a faster rotative speedthan the lower displacement member the displacement members are alternately forced apart and allowed to come together; a compression spring so placed that it exerts an upward pressure on an extension on said lower displacement member and the same pressure downwardly on said upper displacement member, said pressure being substantially greater than that needed 'to lift the lower displacement member and all parts carried thereby and hold the lower interrupted, cam in firm contact with the upper interrupted cam while the bit is in actual use; and means rigidly connecting the lower displacement member to the bit.

pipe; an upper displacement member having an upper interrupted cam on the lower end thereof; means rigidly connecting the upper displacement member to the drill pipe; a lower displacement member having a lower-interrupted cam on the upper end thereof, said upper and lower cams being in contact with each other when the bit is in firm contact with the bottom of the well, the

effective coacting surfaces of said cams being of a shape that would be generated if a line radial to the axis of said assembly were rotated about and synchronously advanced upwardly along said axis; a compression spring so placed that it exerts an upward pressure on an extension on said lower displacement member and the same ,pressure downwardly on said upper displace- .ment member, said pressure being substantially greater than that needed to lift the lower displacement member and all parts carried thereby and hold the lower interrupted cam in firm contact with the upper interrupted cam while the bit is in actual use; and means rigidly connecting the lower displacement member to the bit.

3. A combination of parts for use in the rotary system of drilling wells, which comprises: a drill pipe extending from the bit assembly and up- *wardly through the well to a point .above the top of the well bore; means above the top of the well bore for rotating the drill pipe; means for supporting all or a part of the weight of the drill pipe; an upper displacement member having an upper interrupted cam on the lower end thereof; means rigidly connecting the upper displacement member to the drill pipe; a lower displacement member having'a'lower interrupted cam on the upper end thereof, said upper and lower cams ;being in contact with each other when the bit is in firm contact with the bottom of the well and being so formed that when the upper displacement member rotates at a faster rotative speed than the lower displacement member the displacement members are alternately forced Lapart and allowed to come together; a compression-spring coaxial with said assembly; atension member rigidly secured to one of said displacement -members and extending through said spring; a head on said tension member against which one end of said compression spring abuts, the other end of said spring abutting against the other displacement member in such a manner as to force said displacement members toward each other with suflicient force to hold the cams thereon in close engagement with each other against the weight of any parts which 'might pull said cams apart when the bit is in use; and means rigidly connecting the lower displacement member to the bit.

4. A combination of parts for use in the rotary system of drilling wells, which comprises; a drill pipe extending from the bit assembly and upwardly through the well to a point above the top of the well bore; means above the top of the well bore for rotating the drill pipe; means for supporting all or a part of the weight of the drill pipe; an upper displacement member having an upper interrupted cam on the lower end thereof; means rigidly connecting the upper displacement member to the drill pipe; a lower displacement member having a lower interrupted cam on the upper end thereof, said upper and lower cams being in contact with each other when the bit is in firm contact with the bottom of the well, the effective coacting surfaces of said cams being of a shape that would be generated if .a line radial to the axis of said assembly were rotated about and synchronously advanced upwardly along said axis; a compression spring coaxial with said assembly; a tension member rigidly secured to one of said displacement members and extending through said spring; a head on said tension member against which one end of said compression spring abuts, the other end of said spring abutting against the other displacement member in such a manner as to force said displacement members toward each other with sufficient force to hold the cams thereon in close engagement with each other against the weight of any parts which might pull said cams apart when the bit is in use; and means rigidly connecting the lower displacement member to the bit.

5. In a mechanism for attachment at its upper end to the lower end of a drill pipe which is rotated in a well by means old in the art, said means engaging and rotating the upper end of said drill pipe, the drill pipe rotating said mechanism, and-rotating a bit attached to the lower end of said mechanism, the combination of: an upper displacement member having an interrupted cam on the lower end thereof, the drill pipe being rigidly connected to said upper displacement member which therefore turns at all times with said drill pipe, said drill pipe exerting downward pressure directly on said upper displacement member; a lower displacement member having a lower interrupted cam on the upper end thereof, the bit-being-rigidly connected to said lower displacement member, said cams having faces which cooperate to first force said members apart and then allow the upper displacement member to drop and strike ablow on the lower displacement member; and a compression spring so placed that the upper end of said spring exerts an upward pressure on anextension of said lower displacement member and the lower substantially in excesseof thatneeded to lift the lower displacement member and its attached 13 parts including the bit and hold said cams in firm contact with each other.

WILLIAM H. CLAPP.

REFERENCES CITED 5 The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 10 Re. 15,760 Kammardiner Feb. 12, 1921 701,391 Pruszkowski June 3, 1902 1,225,629 Hensley May 8, 1917 1,501,630 Stoll July 16, 1924 1,518,634 Cason, Jr. Dec. 9, 1924 15 1,653,094 Fleming Dec. 20, 1927 1,667,077 Mecom Apr. 24, 1928 1,688,994 Smith Oct. 23, 1928 Number Number Name Date Mecom Jan. 1, 1929 Zublin May 20, 1980 Bishop Jan. 13, 1931 Fosnaugh May 12, 1931 Billstrom Feb. 16, 1932 Pennington Dec. 27, 1932 Grant Feb. 28, 1933 Harris Mar. 14, 1933 Burt June 25, 1935 Sutlifi Feb. 7, 1939 Foster Apr. 11, 1939 Prebensen Jan. 14, 1941 FOREIGN PATENTS .Country Date Germany Sept. 29, 1916 Certificate of Correction Patent No. 2,495,364 January 24, 1950 WILLIAM H. CLAPP It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction asfollows:

Column 6, line 51, for the words and upper read an upper; column 14, line 8, list of references cited, for Feb. 28, 1933 read Feb. 28, 1982; same column, under the heading FOREIGN PATENTS add 145,849 Germany Nov. 10, 1.903;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the casein the Patent Office.

Signed and sealed this 30th day of May, A. D. 1950.

THOMAS F. MURPHY,

Assistant Oommz'ssioner of Pat ents.

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