US2641816A - Power operated slip - Google Patents

Description

4 Sheets-Sheet l l I I I lullllI-llnlll lul all! W. E. LILJES TRAND POWER OPERATED SLIP June 16, 1953 Filed Oct. 21, 1946 W. E. L\LJ'E 5T RAND INVENTOR. BY fagr (B. M

Fig.2

W. E. LILJ ESTRAN D June 16, 1953 POWER OPERATED SLIP 4 Sheets-Sheet 2 Filed Oct. 21, 1946 Fig. 3

W. E. LILJ'ETRAND IN VEN TOR. inm- 6. M

"an; 1. M

J1me 1953 w. E. LILJESTRAND 2,641,816

POWER OPERATED SLIP Filed Oct. 21, 1946 4 Sheet s-Sheet 4 m f 5?. +6 I04 I03 l9 m AIO a 93 '7 m 7 g ua I I. la: l \06 v 20 4 iii? Fig.7

PRESSURE PUMP w COMPRESSOR WE. LlLJ'E5TRAND INVENTOR. BY 22m- 5. M

Patented v June 16, 1953 v UNITED STATES PATEN T OFFICE POWERFOPERATED f waltermnlailjestrand, Houston, ;T.ex.; assignor to' -:Mission Manufacturing Company, Houston,

Tex arcorporationvof Texas Application 0ctober'21, 1946, sens-1 m. 704;672

The invention relates to a -mechanism for operating the slips used in suspending pipe-during the rotary method of drilling wells.

"With the -aclvent of deeper and deeper drilling, thes'izej-length, -and-weightof the pipe which must be suspended has increased substantially so *that there is 'a definite problemin properly suspending orsupporting the pipe't'o" ii-isurethat it *vvill be firn'ily --hel'd and to then effect release of the slips and supporting structure in such a "manner as to avoid damage and in'jur-yto the pipe to --eliminate the drudgery of handling "the heavy slips, an'dzin "fact; to improve the method *andepparatus for handling the slips and supporting the-pipe.

' It is-one of *the'objec'ts of "the present invention to provide *a power operated mechanism for manipulating *theslips so that they will be auto- "matically retracted to permit a full opening when the slips are raised toinac'tive position.

Another object-of the invention -is=to provide a slip handling mechanism wherein by a straight lift operation the slips are not only with'drawn from'the slip --b'ow1 but are also retracted from interference with operations being condu'c'ted through the rotary table-and slip bowl.

Another object of "the invention is 'to" provide a -slip operating mechanism which will automatically lift and retract" the slips or lower and "insert "the slips when the device is power 'operafted.

Another object of the invention is -to' provide the power "operating mechanism for slips which "can "be moved away from the-rotary table to'an inactive 'p'ositionswhich will -=not interfere' with v "the use of the rotary table when the slips are not '*being used.

raising and lowering a slip operating-ring.

Still another object of theinvention is to pro- 'videa lift ring for slip operating mechanism 'having a trackway therein which will take advantage of the components o'f force encountered so "11 Dlaims. (Cl. ab -263) :as :to lift andiretract the slips in a single operation or to flower land insert the slips in .ahsingle operation.

:slip bowl.

-still ifurther object :of the invention :is "to provide a control assembly for 'slipcperating mechanism.

It is :also :an object of :Lthe :invention .to;pr0-

c -videa:slip operating lift ring having atrackway ref a peculiar configuration such that when a slip is supported therein, I there will she a tendency to retract the :slip 535 80011 as it vis cli'fted out'of the slip bowl.

Still another object of the invention is to .pro- 'vide -'an adapter firing :formotary tables so as to guide a setmf ipowerloperatedislips into the slip bowhupon locking movement :thereof.

still fur ther object of the invention .is :to provide :a po-w er operated slip handlirigmecha- "nism which will "permit .the making up andthe br'eaking out of .pipe joints while the slips are supporting the pipe 'and connectedito the-mechan'ism.

llt 'isan objle'c't of the invention to :balance the supporting structure for slips in a gpower operatedmechan'ismso that ithe-Islips lmayrbe :lifted to a-=position to hemoved laterally from the slip 'bowl and returned thereto 'and'inserted inuthe slip bowl without additional guidance.

Otherand -further obj eats-of thezinvention will be readily apparent when the iollowing description is c'onsidered in connection with the :accompanying drawings, wherein: a

Fig. '1' is a-top plan view looking down :on "the power operating mechanism and illustrating the mechanism as moved 'to retracted position as "shown by the dotted lines.

Fig. 2 is a-side elevation of the mechanism in *useands'howing the slips'in-pipe supporting pcsition in the rotary table.

'Fig. 3 is-'atop-plan view looking down on the operating-mechanism with certain parts broken "away to -i llustrate the construction and showing the retracted position of the slips in ldotted line.

- Fig. is a vertical sectional view showing the slips in pipe supporting position and the Hit-ring loweretl'so as "toha-ve inserted the slips and with the slips and the lift ring shown elevate'd indotted lines.

"-Fig.-"-5-"shows 'a-modiii'ed "form of the configuration of the '-trackway' by "w'hih the retracting movement of thesl'ips is' performe'd.

Fig. 6 shows another modification of the configuration of the trackway.

Fig. 7 shows a diagrammatic arrangement of the power control mechanism with some of the valve assemblies illustrated in section.

Referring to Fig. 2, a rotary table has been illustrated which is supported by the derrick over the location where the well bore is being drilled. This rotary table embodies the stationary base 2 and the rotating top 3 which top is best seen in section in Fig. 4. This top has a non-circular opening 5 therein which is arranged to receive the drive bushings for gripping the drill stem or other pipe 6 which is to be rotated inthe well bore.

It is believed to be well understood that in the rotary method of drilling wells, a section of pipe is connected to the drill bit and this pipe is either gripped by the rotary table or by other suitable section of pipe so that rotation is imparted thereto. As the drill bit penetrates the earth formation, additional sections of pipe are added. When the drill bit is to be renewed or for;some other reason removed from the well bore, the string of pipe thus assembled must be raised, then supported and a number of sections of the pipe removed. This operation is repeated until all' of the pipe has been withdrawn from the well. The bit is changed or such other operation carried on as desired and when drilling is to be reu sumed, the pipe is reinserted usually by adding two, three or four sections of pipe at a time. In thus manipulating the pipe and in fact handling other pipe in .the well bore, that part remaining in the well must be suspended while the sections are being removed or added thereto. The rotary table is provided with a tapered area 8 which is generally known as the slip bowl and is arranged to receive a set of slips l0, usually made up of a plurality of segments ll, three of which are seen in Fig. 3. These segments are usually tapered and have a support face l2 arranged to fit the tapered slip bowl 8 and also provided with the jaw sections 13 arranged to engage the periphery [4 of the pipe 6, so as to firmly grip the pipe and, due to the tapered surface 8, move downwardly in the rotary table so as to firmly and securely support the pipe. 7

When the pipe is to be again moved after having once been gripped with the slips, the pipe must be elevated slightly, then the slips withdrawn. As the wells are drilled deeper and deeper, it is not uncommon to support 200,000 or 300,000 pounds of pipe upon the set of slips. The slips in turn must mavesubstantial weight in order to support such tremendous loads and large slips are heavy and difiicult to handle manually.

The present invention therefore contemplates a slip operating mechanism which is best seen in side elevation in Fig. 2. The essential part of this mechanism is the slip lift ring l5 which is best seen in section in Fig. 4. This ring includes an outer rim iii, a base I1, and the top plate [8. It has an annular opening I9 through the top plate, and the base plate as seen in Fig. 4 is inclined upwardly and inwardly to provide a surface 20 which in turn is joined by a somewhat steeper inclined surface 2|. An upstanding flange 22 forms the inner periphery of the base ring. These plates 20 and 2| are substantial and rigid so as to support the weight of the set of slips.

An apron 24 is arranged inside of the lift ring I5 so as to define a space or chamber 25 therein which is generally annular in form.

This lift ring I5 is provided with a gate hinged at 3! and latched in position in the ring by the latch 32. This gate permits movement of the ring laterally about the pipe such as 6 where the pipe is already in the hole and the lift device is to be used.

Fig. 3 shows the lift ring positioned about the pipe with the gate closed because the latch arm 36 thereof engages over a pin or stop 31 in the lift ring [5. The gate is shown open in the dotted line position and a spring mechanism 39 may be used to hold it in either open or closed position as shown.

The lift ring [5 may be raised and lowered but the arm 40 to which the lift ring is pivoted by the plates 4| and pivot pin 42 as best seen in Figs. 1 and 2.

This arm 40 is in turn pivoted by the pin 43 upon a yoke 44 aflixed to the housing 45 which is arranged to telescope over the cylinder 46. Arranged inside of the housing 45 is a plunger 41 as best seen in Fig. 7. The chamber 48 within the cylinder 46 is arranged to receive a fluid under pressure from the pipe 49 whichis controlled by a valve 50. In this way pressure fluid may be introduced to or released from the chamber 48 so as to elevate the housing 45, the arm 50 and the lift ring H5 or to lower it as desired. Arranged on the housing 45 is an arm 52 which carries a stem 53 extending into a cylinder 54. This cylinder 54 is arranged to receive or discharge fluid under pressure through the piping connection 55 which is also connected to the valve 50. The application of pressure in this cylinder 54 applies a positive movement to move the operating mechanism and the slips downwardly into pipe receiving position. In other words, the slips m ay be operated by power to be lifted upwardly and may alsobe power actuated in moving downwardly. The particular details of the slip manipulating mechanism include a particular form of slip segment H where there is an upstanding portion or post 60. Afiixed in this post is an outwardly and downwardly extending handle 6| having an anti-friction member 62 such as a collar or other device to reduce the friction of the handle'upon the portions 20 and 2| of the base plate ll. These portions 20 and 2| serve as a trackway for the handle and as seen in Fig. .4 the lift ring l5 has been lowered so as to allow the slips to move from the dotted line. position of Fig. 4 to the full line position. This movement has been accomplished first by virtue of the beveled face 65 on the lower end of the slip segments, which face 65 is arranged to abut a beveled adapter ring 66 carried by the top of the rotary table 3. It'will be particularly noted that the dotted line position of the slips in Fig.4 illustrate the pipe engaging face I3 thereof as being retracted radially outward beyond the narrowest portion of the passage 6! through the rotary table. In this manner a full hole opening is provided for. manipulation of the tools and pipe. The manipulating construction for the slips is so arranged that when the slip ring moves downwardly, the toe 65 of the slip will move off of the adapter ring- 66 and slide downwardly into the drive bushing opening 5 and the slip bowl 8.

In other words, the force of gravity pulling the slip down will cause it to slide inwardly into pipe supporting position.

When the slips are to be lifted, the power ,mechanism is operated to raise the slip ring I5.

The, vertical upward movement of this slip ring amnesia -forces the portion II of theitra'clcway. agaiinstzthe anti-efrictiomportionofothe handle'sitl and begins the :lifting movement :of the slips. Due to the :inclined configuration ;of the portion 21 the lifting force is divided into vertical and horizontal components, the horizontal componentitendingto Lurgeithe. handle .61 and rthe slip; segments 2! ILr-adi- Jally outward. .As :the ;slip segments move out of -.the taperedporti'on .3, :they will ;1bei.retracted to move upwardly along ..l3h6.1TSl1If8iC8 of the drive :bushing Band when the beveled -toe portion .65 reaches the top of the slip, :further outward :movement is permitted. 'By'this'time,; the-;outer tor anti-friction portion LOf the :handle 21 :has moved off the steep portion aof the trackway .21 :andzonto the surfacelflrasxbest seen inzthe dotted 'line portion of Fig. :4. positionwstill .con- 'tinues to urge. the :slips outwardly and the full elevated position, the slips 'will ;.move radially outwardly until they abut the stop ring 2 2 which ."forms the periphery LOf the-trackway. Thexlotted line position in Fig. :4 shows the slipjpost .Gllabutting this ring.

It seems obvious that when the'lift ring again lowered, that the slips :will negotiatean inward and downward movement because part-of the weight of the slips may 'bessupportedin the various portions of the .rotary table to relieve some of the weight on the handles and anti- :friction means, thus allowing the handle totravel :upwardly .on the trackway until such time :as the slips are fully supported in theslip bowl rand the lift ring moved downward to its lowermost position as seen in'FigA.

On this downward movement the apron 24 comes into service and may engage the antifriction portion -62 of the handles, urging the handles and the slips inwardly due to the inclined surface of such apron engaging the upper .part of the slip handle.

Fig. 5 shows a modified .form ofthe base 17, wherein a straight :frusto-conical surface :19 has been provided so that there is a 'uniform"movement as distinguished from the movement :obtained with the configuration of the trackway shown in Fig. 1. The remaining structure is identical with that previously described.v This form may be used .butin actual operation, a greater tendency to move the slips outwardly is desired in the initial movement, whereas,

tendency need not be so great toward the upper' end of the lifting movement .and thus the two inclinations of the trackway have beenprovided in Fig. 4. Fig. 5 having-the straight trackway may be satisfactory in some operations.

Fig. 6 shows a modificationor comprise between the forms of Fig. 4 and Fig. 5 in that the surface 72 is an outwardly and downwardly flared or dished surface which gives a greater opening force which is taperedoif as theslips reach their maximum elevation.

i The plan view of Fig. .3 illustrates details of the slip assembly and the supporting handles whereby a satisfactory operation is obtained. It will be noted that the slip segments are three in number and the two lateral segmentsare hinged by the'pins l4 and to themainslip-segment .16. Any desired number of segments may be used but they arepreferably hinged together so as to insure satisfactory operation.

As these slip segments .are raised and move backwardly and away from the pipe, the segments H and 18 will swing outwardly and rearwardlyon an are around thepins .M and .15'respectively. This action is obtained-due to the 6 "fact that the handles I19 .on the ssegment 11:1 .and 2'81} on the segment .18 :are angularly :disposed with respect to the slip segments so that'the .handles tend to run backwardly .and downwardly-on the trackway so :as to move the slips backwardly away from the pipe to the dotted line position of .Fig. .4. This :movement not only withdraws 1the slips from .engagement'with the pipe butalso opens ..up the slip segments to such a position thatithe entirea'slip rings may be swung laterally to the dotted line POSlti'OllOfrFlg. 1-1 *with thepipe :passing between the segments :17 and '18 ."of the .slip. It .seems :obvious that the slips may be stopped in their :rotation in the position of Fig. :3 or if 'theyt-are in some' other position, the opera- :tor may manually roll the slips around on the 'tra'ckway'so asto arrange them in full open posi tion.

TIf -the slips have :beenraised, the arms 713923116. '80 "will have rolled :to the dotted line :position of 'Fig. .3 during the simultaneous retraction of the main slip .16 andzall of -the;=parts will then :be .in the dotted lineposition of Fig. 3.

The-main sliplfi is supported by two arms 31-! 'ElfldBZWhlCh are angularly disposed with respect to each other and the mainslipandarearranged to balance the slip with a direct radial outward and inward -movement without any "circular traveling. These arms are shown in the 1 retracted or dotted line position of :Fig. 3. :Upon lowering of the lift ring, the slim will-travel inwardly but the pivots l4 and 15 avill-cause them to move circularly aswell and'they will then "return to the full line position of Fig. 1.

Particular attention is directed to the arrange: .ment of the anti-friction roller bearings -or such other device as may beprovided so as-to obtain suitable rolling action .upon the trackway. It is not uncommon for the driller to use the rotary table for turning thepipe Lin uncouplingthe pipe sections by. holding the sectionzabove the rotary table with suitable mechanism grippingthe pipe with the slips as seen in Fig. 4 and then rotating the table. Inasmuch as the lift ring-l5 is .held stationary by the arm 49, .it is desirable to permit the slips under these circumstances to turn with the rotary table, and anti-friction rollers as fShOWlT in the drawing are therefore arranged on case may be.

. In order to hold the ring l5 in extended position relatively to the arm ll], a latch pinis "shown in Figs. 1, 2, and :4. This pin may be dropped through openings .in the plate H, the :ring f5 andthe end "of the arm 40 as best seen in the enlarged view-:of Fig. 4.

Theoperating mechanism described but briefly heretofore is seen in Fig. 2 :and includes in addition to the structure previously described, the upright guide members 50 which as :seen in Fig. 1 are in the form of channels to receive the guide rollers 9| carried by the extension arm- 92 onthe.low.er end of the housing and upperyoke A bumper or adjustable stop device 93 has been provided and is best seen in Fig. 7. The spring thereon will be of sufiicient strength to support the entire lift ring and moving parts of the power assembly so that it acts as a stop but in event some object should strike the lift ring or other parts, the shock thereof would be cushioned by this device. Both the spring thereof and the position of the stop 93 may be adjusted vertically.

When the lift ring is to be moved laterally away from the rotary table, the latch pin 95 seen in Figs. 1 and 2 may be removed so that the arm 40 may pivot about the support pin 43.

The valve 50 is generally known as a fourway valve so that it may be positioned as seen in Fig. 7 to admit pressure fluid through the pip 49 to elevate the slips while in turn permitting the exhaust of pressure from the cylinder 54 to exhaust through the pipe 55 and the outlet 91. When the lift ring is to be lowered, the valve will be turned so as to permit the pressure to be relieved in the line 49 through the outlet 9'! while the inlet pressure fluid is directed through the valve to the pipe 55 to effect a positive downward movement of the slip ring through the plunger cylinders 53 and 54.

A detailed control valve mechanism is shown in section in Fig. '7 as having been incorporated in the base of the cylinder 46.

The pressure fluid entering the chamber 46 through the pipe 49 will be prevented from return through the same path by a check valve IBO..

The entering fluid moves upwardly through the passage IOI, lifting the valve [.32 and permitting the pressure fluid to pass through the opening I93 in a cage I02. This pressure then exerts itself against the plunger 4? and results in elevation of the housing 45 to which the plunger 4! is connected at its upper end.

In order to accurately control the movement of the plunger 41, and consequently the movement of the lift ring I5, a series of valves have been provided in the base portion of the plunger 46 as seen in Fig. '7. One of these is a direct safety valve I99 which will be set to relieve any pressure in the cylinder extending a predetermined amount, such for instance as that caused by striking of the mechanism by the falling of any object.

If the operator desires to release the pressure in the chamber 48, the release valve ID'I may be opened by turning the screw I98.

Neither of these Valves I98 or I'll! will be normally used because the escape of the pressure fluid will be governed by a control valve III]. This control valve has a small seating surface III which remains closed during the introduction of pressure fluid to lift the ring It also has a larger surface or shoulder II2 which may be exposed to pressure introduced through the branch line II3 which leads off from the pressure line 55 leading to the cylinder 54 for forcing the mechanism downwardly. Thus when the valve 59 is manipulated to cause the lowering of the lift ring, the pressure applied in the pipe 55 and the cylinder 54 against the piston or plunger 53 will also pass in the branch pipe I I3 and effect opening of the valve IID against the spring II 5 whose compression may be adjusted.

The opening of the control valve IIB allows escape of pressure from the chamber 48 past the valve I62, which is normally held open by its supporting spring, and into the outlet Dassage H8. The amount of pressure fluid permitted to escape from this outlet passage H8 is controlled by a choke screw I20 which'may be turned to adjust the escape opening I2I and allow the lowering movement of the piston 41. It is desired of course to prevent shock of the dropping of the slip ring and the slip and with this in mind, an air chamber I2I has been provided in the base of the plunger 41. A weight disk I22 is freely slidable in this chamber I2I and is arranged to engage the stem I23 extending upwardly from the valve I92. As the pl 4'! moves downwardly below the position shown in Fig. 7, the weight of this disk I22 will overcome the spring supporting the valve I02 and cause the valve to close. The closing of this valve I02 traps the pressure fluid in the chamber 48 and. the compression thereof serves to slow down the movement of the plunger 47 and will bring it to a stop at about the time that the arm 42 engages the stop pin 93.

To insure the full lowering movement of the lift ring I5, however, a bleed nipple I25 is shown as positioned in the base of the cylinder in a passage leading to an outlet II8. This bleed opening I25 is normally held closed by a valve I26 urged against the nipple but which will be so set as to permit the gradual escape of more than a predetermined pressure from the chamber 48. A check valve prevents the escape of all of the pressure from the chamber 48 so that the chamber may be readily filled again without having to build up the residual pressure which can be trapped by this check valve I26.

It seems obvious that these various valves may be adjusted and arranged so as to accurately control the movement of the plunger 41 and the lift ring I5.- The manipulations previously described will be reversed when the valve 50 is reversed.

A practical advantage of the mechanism just described will be apparent from Fig. 1 due to the provisions of the double pivot pins 42 and 43. The removal of the locking pins 35 and 95 permits a swinging and sliding action of the lift ring and the arm 40 so that the gate 30 may be swung around as the lift ring moves away from the pipe. A drillers position on the rig is usually adjacent the upper right hand corner of Fig. 1 so that the lift'ring, when moving away from the pipe, will permit a clear view of the rotary table by the driller and so that the lift ring may be readily swung clear of the rotary table and to a now unused portion of the derrick fiOOr below and -to the right of the operating mechanism as shown in dotted lines of Fig. 1.

The parts are so arranged that a single operator may push the lift ring to the inactive position or may return it for use. The ring may be returned from the dotted line position of Fig. 1 by the operator grasping the gate and pulling on the ring. The ring will then first pivot about the pin 42 so that the gate opening will be turned toward the pipe. A pull across the top of the rotary table will then cause the pin 43 to begin to turn so that the ring will finally assume the full line position of Fig. l. The latch pins and may be now dropped into position. This slip handling mechanism is so simple and readily operable that it has been found that the drillers and operators will use it for supporting and handling a pipe where only a single connection is to be made and of course it is to also be used when doubles, thribbles or fourables of pipe are being connected.-

Broadly the invention contemplates a simple and economical power operated slip mechanism which will actuate the slips-both vertically and laterally from a single support.

Whatfis claimedis:

1'. Asliproperat'ingg mechanism; including: a lift ring adapted for placement overarotary drill.- ing table, said. ring; having: an opening and? gate for passage of. the" ring; to and from a-.pipe,, aset of slips to. fit. the? rotary table: and suspendapipe therein, said slips being suspended from saidring, an arm pivotally supported. radially of the table" to support said' ring: for: lateral swinging oversaid" rotary'table, rotatablermeans onv saidslips which? is rotatable inisaid ring, as saidslips rotate wherrgrippin'g theipipeiinciudinga: handle, a: trackway said; ring: to guide said: rotatable means and thereby said handle as the ring is raised so" as to retract the slip; segments and;provide-a full hole. opening,. and means to raise and lower said arm and lift ring, said' rotatable.means.normally beingdisposed above said trackway when said slips are gripping the pipe.

2-. a slip operating mechanism including a lift ring adapted for" placement over a rotary drilling table, said ring having an openingand.

gate forpassage of the ring to and fromapip'e, a set of'slips to fit the rotary table and. suspend a pipe; therein, said'slips being suspended. from said ring; an arm pivotally supported. radially of thetable to supportsaid ring for. lateraliswinging over said rotary table, rotatable means-n said slips which is rotatable. in said ring. as said slips rotate. when gripping the pipe including a handle, a trackway in said ring. to guide said rotatable means andthereby saidlhandle. aathe ring is raised' so as to retract the. slip segments and provide a full hole opening, and meanstlo raise and lower said arm and' l'ifjt 'ring,.said' r0. tatable means normally being disposed above said trackway when said slips are gripping the pipe, said handles having anti-friction means thereon to travel said trackway.

3. A slip operating mechanism including a lift ring adapted for placement over a rotary drilling table, said ring having an opening and gate for passage of the ring to and from a pipe, a set of slips to fit the rotary table and suspend a pipe therein, said slips being suspended from said ring, an arm pivotally supported radially of the table to support said ring for lateral swinging over said rotary table, rotatable means on said slips which is rotatable in said ring as said slips rotate when gripping the pipe including a handle, a trackway in said ring to guide said rotatable means and thereby said handle as the ring is raised so as to retract the slip segments and provide a full hole opening, and means to raise and lower said arm and lift ring, said rotatable means normally being disposed above said trackway when said slips are gripping the pipe, said trackway com-prising a plurality of inclined surfaces sloping radially outwardly and downwardly so that such trackway serves to control the movement of the slips.

4. A slip operating mechanism including a lift ring adapted for placement over a rotary drilling table, said ring having an opening and gate for passage of the ring to and from a pipe, a set of slips to fit the rotary table and suspend a pipe therein, said slips being suspended from said ring, an arm pivotally supported radially of the table to support said ring for lateral swinging over said rotary table, rotatable means on said slips which is rotatable in said ring as said slips rotate when gripping the pipe including a handle, a trackway in said ring to guide said rotatable: means and thereby said handle. as the. ringis raisedso as to: retract the slip segments and provide a full hole opening, and means to raise and lower said arm and. lift ring, said rotatable means. normally being dis.- posed above said trackway when. said slips are gripping the pipe, said. trackway comprising a frusto-conical surf ace..

' 5. A slip operating mechanism includinga lift ring adapted for. placement over a. rotary-drilling table, said ring having an opening and-gate for passage of the ring to and. from a pipe, atset of. slips to fit the rotary table and suspenda pipetherein; said slips being suspended: from said ring; an arm pivotally supported radially of the table to support said ring for lateral swinging over said rotary table, rotatable meanson said slips which' is. rotatablein said ring as said slips: rotate when gripping the pipe including: a handle, a trackway' in said ring to guidesaid rotatable. means andlthereby" said handle as the ring is raised so as to retract the slip' segments and provide; a full hole. opening, and means to raise and? lower said. arm and lift ring; s'aidirdtatable means normally being" disposed. above said ring, said slips including a pairof slipssh'aw ing unconnected longitudinaled'ges, pivot means connecting-their otherlongitudinal edges; handle means oneach of saidslips extendingoutwardly and rotatable in said ring, a downwardly and outwardly inclined trackway in said ring engageable by said handle means so that the slips are lifted from within the drilling table and retracted by pivotal movement of the pair of slips about their pivot means to separate said unconnected longitudinal edges to provide a full hole opening when the lift ring is lifted.

'7. A slip operating mechanism including a lift ring adapted for placement over a rotary drilling table, said ring having an opening and gate for passage of the ring to and from a pipe, a set of slips to fit the rotary table and suspend the pipe therein, said slips being suspended from said ring, said slips including a pair of slips having unconnected longitudinal edges, pivot means connecting their other longitudinal edges, handle means on each of said slips extending outwardly and rotatable in said ring, a trackway in said ring engageable by said handle means and tapering downwardly and outwardly thereon whereby the slips are lifted and retracted by pivotal movement of the pair of slips about their pivot means to separate said unconnected longitudinal. edges as said ring is moved upwardly.

8. A slip operating mechanism including a lift ring adapted for placement over a rotary drilling table, said ring having an opening and gate for passage of the ring to and from a pipe, a set of slips to fit the rotary table and suspend the pipe therein, said slips being suspended from said ring, said slips including, a pair of slips having unconnected longitudinal edges, pivot means connecting their other longitudinal edges, handle means on each of said slips extending outwardly and rotatable in said ring, a trackway in said ring engageable by said handle means and taper- 11' ing downwardly and outwardly at decreasing rates of taper toward the periphery of the ring whereby the slips are lifted and retracted by pivotal movement of the pair of slips about their pivot means to separate said unconnected longitudinal edges as said ring is moved upwardly.

9. A slip operating mechanism including a lift ring adapted for placement over a rotary drilling table, said ring having an opening and a gate for passage of the ring to and from a pipe, a set of slips to fit the rotary table and suspend the pipe therein, said slips being suspended from said ring, said slips including a pair of slips having unconnected longitudinal edges, pivot means connecting their other longitudinal edges, handle means on each of said slips extending outwardly and rotatable in said ring, a trackway in said ring engageable by said handle means and tapering downwardly and outwardly at successive, decreasing inclinations to the horizontal so that the slips are moved upwardly and outwardly as the ring is lifted.

10. A slip operating mechanism including a lift ring adapted for placement over a rotary drilling table, said ring having an opening and a gate for passage of the ring to and from a pipe, a set of slips to fit the rotary table and suspend the pipe therein, said slips being suspended from said ring, said slips including a pair of slips having unconnected longitudinal edges, pivot means connecting their other longitudinal edges, handle means on each of said slips extending outwardly and rotatable in said ring, a trackway in said ring engageable by said handle means and extending arcuately downwardly and outwardly so that the slips are moved upwardly and outwardly and retracted by pivotal movement of the pair of slips about their pivot means to separate said unconnected longitudinal edges as the ring is lifted.

11. A power assembly for operating pipe slips over a rotary table comprising, a ring disposed over but independent of the table and having an opening and a gate for passage of the ring to and from a pipe, an arm pivotally supported radially of the table, a pivoted connection between said ring and said arm, and means to raise said arm to raise said ring and slips to clear said ring and slips of the rotary table opening, a set of slips suspended from said ring, supporting means extending outwardly from said slips and confined in said ring for circumferential and radial movement relative thereto, said ring forming a circular trackway for rotation of said supporting means on and relative to said trackway when said slips are engaging a pipe therebetween.

WALTER E. LILJESTRAND.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,341,702 Black June 1, 1920 1,499,225 Krell June 24, 1924 1,733,010 Green Oct. 22, 1929 1,817,467 Thompson Aug. 4, 1931 1,878,372 Box Sept. 20, 1932 1,909,601 Young et a1 May 16, 1933 1,986,284 Penick Jan. 1, 1935 2,231,923 Koen Feb. 18, 1941 2,269,888 Sharp Jan. 13, 1942 2,274,273 Miller Feb. 24, 1942 2,283,866 Failing May 19, 1942 2,340,597 Kelley Feb. 1, 1944 2,545,627 Moore Mar. 20, 1951

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