US1720942A - Rotary expansive tool - Google Patents

Description

July 16, 1929.

L. S. CAMPBELL ROTARY ExPANsIvE lrooL Filed Jan. 19, 1928 2 Sheets-Sheet l Mor/26g July 16, 1929- L.. s. CAMPBELL ROTARY EXPANSIVE TOOL 2 Sheets-Sheet` 2 Filed Jan. 19. 1928 l Ml Patented kJuly 1e, 1929.

UNITED STATES/ PATENT oFFIC'E.

LAWRENCE S. CAMPBELL, F KANSAS CITY, MISSOURI, ASSIGNOR TO JOHN G'RANI,

, OF LOS lANGELES, CALIFORNIA.

ROTARY EXIIPANSIVE] TOOL.

Application led January 19, 1928. Serial No. 247,824.

This invention has to do with expansive well tools, and,'in the typical embodiment heredescribed, with devices of the type generally known as expansive reamers or underreamers, and particularly with rotary underreamers; the particular objects and accomplishments of the invention `will perhaps be best understood from the subjoined specific description of a preferred embodiment of the invention; but I may state preliminarily that among the various objects of the invention there is the object of providing -a reamer which does not depend upon the action of a spring for its expansion but is expanded by a positive movement, and is likewise contracted by positive movement. Also involved in the invention, and adapted to the particular features of design which embody other characteristics, is the feature of locking the cuttersl in their inward `or contracted positions so that they may be prevented from riding the pipe while the reamer is passing through the well pipe. In the characteristie typical design hereinafter explained' the structure and operation are such that, whenA the reamer passes below the well pipe and is to be expanded, positive rotation of the drill stem in a righthanded direction causes positive expansion of the reamer. Then when it is desired to contract the reamer it is not necessary to rota-te the drill pipe in the opposite direction, or left-handedly, but -it is only necessary to pull the reamer up against the bottom of the well pipe or well pipe shoe ".3 when it will be immediately contracted. In this contracted position the cutters are held inwardly so that they do. not press against the pipe, and the reamer maybe withdrawn from the`wel. Upon subsequent insertion the reamer may Y tracted condition in which it has been withdrawn from the well, or it may be placed in what maybe termed its normal contracted condition; but as will be noted hereinafter, from either of its contracted conditions the reamer may be thrown to its expanded posi-v tion'by positive right handed rotationl of the drill stem.

In thesillustrative embodiment of the. invention hereinafter described there are many other characteristic features, such as the forvmation of the cutter carriers, and their engagement and vinteraction with the expand- `the parts in the be either inserted in its conmay be either regarded as a mg cams, etc., but all of which will be best. understood when the embodiment is consid-Y position, this section being taken as indicated by line 2-2 on Fig. 3;

Fig. 3 is a cross section on line 3-3 of Fig. 2;

-Fig 4 is a cross-section yon line 4.-4 of F ig.2; a

Fig. 5 is a section similar to that of Fig. 2.

this section being taken as indicated by line 5-5 on Fig. 6.

Fig. 6 is a cross-section on the line indicated 6*(5 on Fig. 5;

Fig. 7 is a vertical longitudinal section of the part-s showing them l in the contracted vposition they assume as they are drawn up through the pipe, this section being taken as indicated by line 7-7 on`Fig. 8;

Fig. 8 is a cross-section of the reamer taken as indicated by line 8 8 on Fig. 7; and

Fig. 9 is asimilar cross-section showing position which they assume just before going back to the position shown in Figs. 2 and 3. In-the drawing there is shown a reamer body 10 which for the purposes of the specific design herein delineated is made up of an uppenhead 11 and lower hea-d 12 joined together longitudinally by connecting members 'or webs 13. For purposes of assembling and disassembling the particular design herein shown these webs 13 may be releasably connected with one of the heads, as for instance by the screws or bolts 14, one of which is shown in Fig. 1. The body as thus made up sort of cage with upper and lower heads, or 'may be regarded as a slotted body (theslots lying between adjacent connecting webs 13) with an internal bore (the space inside the webs 13). A mandrel is provided which extends longitudinally through the body, bodiment is shown as made up ofrseveral interconnectedparts. The upper mandrel portion 15 extends through upper head 11 and has at its upper end the usual tapered and threadedl pin 16 for connection with a drill stem kas shown at 17. The middle mandrel portion 18 is the cam carrying part of the 'mandrel and it extends vertically between the and in this particular emtwo heads of the body, being screw-threaded at 19 to the upper' mandrel portion. The lower mandrel portion 2O is screw-threaded at 21 to the middle mandrel portion and has at its lower end a screw-threaded box 22 to receive the threaded pin of a drill bit 23. Although I have shown the mandrel thus as made up of three separate parts removably joined together, and although for some reasons it may be desirable to thus construct the mandrel, the mandrel can be made in a single piece; and as in operation it acts as a single member I shall hereinafter refer to this composite mandrel merely as the mandrel except where otherwise specifically stated.

Near its upper end the mandrel passes through a bore 25 in the uper end of upper head 11, in which bore the mandrel is both rotatable and longitudinally movable; and near its lower end the mandrel has the same kind of bearing in the bore 26 of the lower head.

A coil spring 27, within upper head 11, nor-l mally presses the mandrel down, the lower end of this spring rests upon a mandrel shoulder which may conveniently be formed by a ring or washer 30 which surrounds the mandrel and rests upon the upper faces of the uppermost cam members 32. These cam members are arranged in sets, and of the sets there may be any suitable number, depending upon the number of cutters or cutter sets used in the reamer. In the particular design here shown I utilize three cutter sets and therefore three cutter carriers and three sets of cam members. Likewise each set of cams (each of the vertical rows of cam members 32) may contain any desired number of cam members, depending` upon the number of separate cutter carrying arms that is utilized in each cutter carrier. From a consideration of the detailed description of structure and operation which follows it will be readily recognized that my invention may be applied to cutter' carriers which embody but a single extendine` cutter carrying arm-in other words to cutter carriers Awhich are not furcated into a seriesof vertically spaced arms-or which have the vertically spaced recesses which the spaced arms specifically provide-or, as shown in the drawings, to cutter carriers having any desired number of vertically spaced cutter carifving arms. One advantage in using cutter carriers with a plurality o f vertically spaced arms or vertically spaced recesses is, as will be understood from what follows, that the vertical movement of the mandrel and the cam members need not be so large in order to move a cam member vertically from a position where it is behind a cutter carrier or cutter carrying arm to a position where it is above the carrier or carrier arm or in register with a recess. Another advantage ot using a cutter carrier divided into a number of vertically spaced arms lies in the fact. that a number of separate cutter members, such as separate rollers, may be utilized, and the roller mandrel given very solid support at closely spaced points along its length. Each of the cutter carriers`35, in the specific embodiment shown in the drawings, is here shown as-a. swinging cutter carrier. It will be recognized that the essential characteristics of the cutter carrier for this reamer require merely that the cutter carriers shall be movable inwardly and outwardly to and from the central axis of the reamer; and, broadly speaking, the cutter carriers can be mounted so as to move in any suitable manner. But for purposes of simplicity of structure and surety of action I choose to mount the cutter carriers pivotally to swing about their axis pins 36 which are loca-ted on vertical axis lines near one of the carrier edges. The opposite edge portion of each carrier is divided into a number of vertically spaced arms 40 which allow sutlicient space between them for the inter-position of roller cutters 41 mounted on mandrel pins 42 each of which preferably extends vertically throughout the vertical length of a cutter carrier. Thus in the particular design here shown each mandrel pin 42 carries three roller cutters 41, and cach separate roller cutter 41 is thus supported on a mandrel pin which is supported immediately adjacent each roller cutter by an arm of the carrier. And, as will later be seen, as each Acarrier arm is directly supported from the interior by a cam member, the radial and circumferential thrust support of each roller cutter becomes very strong and direct, all

of the parts being put intodirect compressive Y l or shearing stress rather than having any bending stresses imposed upon them.

Located within the lower head 12 there is a cutter expanding sleeve 50 which has a frustro conical head 51 pressed upwardly by a spring 52 against extensions 53 which are provided'on the lower ends of cutter carriers 35. The function of this sleeve and conical head, operated by the rather light spring 52, is merely to press the cutter carrier outwardly against the wall of the drill hole to insure sufiicient contact of the cutters with the wall to retard rotation of the cutters and the reamer body suticiently to give positive expanding action when the mandrel is rotated. However, because in the average case the cutters and. also the cutter carriers are in more or less forcible engagement with the wall of the hole when the tool is let down to the point where reaming operations' are to begin, it may not be necessary to use the cutter expanding sleeve and head.

For the particular design here shown,l as I have said before, cam members 32 are arranged in three sets, each set in this particular instance comprising a vertical row of four vertically spaced cam members 32. These cam members are so vertically spaced, as shown yin the various views, that in the posi'- r rotatively locked together.

tion of Fig. 2 and Fig. 5 the cam members are in horizontal planes 'corresponding to the horizontal planes of the carrier arms 40; so that when the mandrel and the cam members are rotated from the position of Figs. 2 and 3'to the position of Figs. 5 and 6, the cam members are moved around directly b'ehind the several carrier arms and, in these last positions, directly support the outer swinging ends of the carrier arms. This action takes place with the mandrel and the cam members' in their lowermost positions, the downward movement of the mandrel being limited bythe engagement of' collar 55 with the upper surface of upper head 11, or

with an intermediate collar 56 which is placed above head 11.

In the positions shown in Figs. 2 and 3the cutter carriers arein their innermost positions and the cutters are retracted toward the center ofthe tool. By relative rotation of the mandrel right-handedly, looking down upon the tool, cam members 32 are thrown from the position of Fig. 3 to the position of Fig. 6. During-this rotation the inwardly extending noses 40a of the carrier arms ride the cam faces 32a and are pressed outwardly; and as the cam members come finally to the position of Fig. 6.y the `noses of the cams move into the notches 40h of the carrier arms, so that the parts then interengage and interlock in the position of Fig. 6. It will be noted that the notches 401 are so formed that the cams cannot be rotated further in a righthanded direction, the cam noses coming up against the walls of the notches, and the cutter carriers being prevented from swinging further outwardly by reason of engagement of their lower ends at v58 with upstanding anges 59 on t-he lower body head l2. Thus, upon continued right handed rotation of the mandrel thecutter carriers arelocked in their protracted or expanded positions and the mandrel and cutter carriers and body are all And it will be noted also that the carrier notches 40h are so formed that inward thrust which would tend to swing the cutter carriers about their axis pins 36 cannot force the cams back in a lefthanded direction and away from the cutter carriers. Consequently inthis described' position of the parts, all of the parts are etectively locked against relative movement by any stresses imposed upon them.

When itis desired to withdraw the reamer from the hole and upv through the well pi e l) backward (left-handed) rotation of the 1;ill stem is not necessary in order to contract the cut-ters. It is only necessary to pull the ream- -er up. until either the cutter carriers or the uppermost cutters come into contact with the lower edge of the pipe. Further upward movement of the drill stem will then cause -upward movementof the mandrel with relation to the body and cutter carriers, comand 1ts cam members up to the relative elevated position shown in Fig. 7. Spring 27 is strong enough that it will normallysupport the weight of the whole tool and of the drill bit attached to its lower end and always keep the parts in the relative vertical position shown in Fig. 2 while drilling and reaming are in progress; but the spring may be compressed by pulling the tool up against the lower end of the casing. the cam members 32 are moved directly upwardly from their positions shown in Figs. 5 and 6, until they occupy the relative elevated positions shown in Figs. 7 and 8'or alittle higher than shown there; t-he cam members being then above their respective carrier arms and registering with the spaces between carrier arms, which spaces are'at least of as great vertical width as the cam members.. The cam members having assumed this position then further upward movement of the mandrel, and upward movement of the body and carriers with it will cause the carriers -to lswing inwardly by reason of engagement of'their upper beveled edges 35a with the lower -end of the casing. These upper beveled edges or corners 35":l extend along a considerable length of the uppermost curved carrier arms 40 as is best showny in F ig. 1, so that a curved beveled edge of some length is presented to the lower end ofthe casing giving good and smooth contact with the casing or its shoe and precluding any liability of the'carriers cutting into the casing and causing any binding by reason of edge toedge riers are thus moved moving inwardly intermediate the spaced cam members 32 until the carriers and cut- `ters are contracted suiiiciently to pass within the casing, as shown in Fig. 7. Then the spring L27 moves the the cam'members are moved down with a fairly heavy pressure against and upon the upper faces of the carrier arms, as shown in the position of Figs. 7 and 8. The whole pressure of spring 27 is exerted in pressing the cam memberslown on-the carrier arms andthus the ycarrier arms are held or locked in their inward contracted position for movement through the pipe. Although of course the carrier arms could be moved outwardly by a suliicient force, there is no such force applied to them while being moved through the pipe. In fact if any force is applied to the carrier arms during such movementit will be an inward, force due to the cutters or carriers coming in contact with s ome locally "smaller or inwardly deformed part ofthe l pipe, which would do nothing but force the carriers inwardly a corresponding distanceg 'and the carriersl would then stay in that inward position and out of normal contact with i the pipe.. When the tool reachcsthe surface 1t may,

Then this occurs v parts relatively so that if desired, be subsequently put back through tions. It is not the spring which tends to exthe pipe in/the condition shown in Figs.I 6 /pand the cutters.

and 7. In this condition the carriers and cutters are still locked against pressing outwardly against the pipe. If reinserted in the well in this condition then when the tool reaches the place where reaming operations are to begin and the cutters are again in contact with the formation, relative right handed rotation of the mandrel and cams will move the cams first from the position shown in Fig. 8 to the position shown in Fig. 9. In the specific design herein shown the cams in this movement will contact somewhat with the roller cutters il and temporarily move the cutters and carriers outwardly while the cams pass the cutters to reach the position of Fig. 9; but that temporary outward movement is of no significance. lVhen the parts reach the relative positions of Fig. 9 the cams are still resting upon the carrier arms 40 and the arms and cutters are thus locked against outward or expansive movement. And the parts may be, if desired, put into the position of Fig. 9

. before the reamer is lowered through the casing. In any case, right handed rotation of the mandrel from the position of Fig. 9 will, as apparent from an inspection of that figure, immediately move the cam members to the position of Fig. 3, the cam members then being out of engagement with the cam arms, and spring 27 will then immediately move the mandrel and the cam members relatively downwardly to the relative position of Fig. 2, the carriers and cutters being still contracted). And it may be noted thatthe partsmay be, if desired, put into this last mentioned relative position before being lowered through the casing. In this position of Fig. 3 the carriers and cutters are not locked against outward expansive movement but are free to swing outwardly, or are movedoutwardly under the light pressure of expanding spring 52, if that spring is used. However, even in the last mentioned positions of the parts, and particularly `if spring 52 is not used, .the cutters will not forcibly ride the pipe on the way down. There is no spring action, or at least no heavy spring action, act-ing in any one of the three collapsed positions of the parts, to force the cutters outwardly and expand them,`as is the. case in any usual underreamer.

In the average underreamer, where a spring is used, that spring has a constant tendency to expand the cutters, andusually by a wedging action which, if anything, is enhanced by y the relatively upward drag of` the cuttersvon the pipe as the tool is lowered through the pipe. But in my reamer the only function of the spring is to hold the parts in what mav be termed their normal relative position of longitudinal movement and to provide that force which locks the cutters against expansion when they are in their contracted posi- From what has been said it will now be readilyv understood how the reamer, when it is put vdown through the pipe in any one of its contracted positions, is thrown to its expanded. position by positive right-handed rotation of the drill stem, and without the use of any relative longitudinal movement; and how the cutters are contracted by the positive relative longitudinal movement caused by drawing the tool up against the lower end of the casing, and how when the cutters are thus contracted there is no force tending to make theml press heavily against the pipe; and how the cutters are in fact locked against outivard movement to press against the pipe'wall.

VI have described the present embodiment of my invention as an underreamer; but the invention is applicable to expansive and contractive tools used for other purposes. In fact the invention may be applied to any expansive and contractive tool in which the operations of expansion and contraction, as herein described, are applicable or desirable. For instance, the invention is particularly applicable'to pipe or casing perforators or cutting off tools, and needs no further description to show how my expanding and contracting mechanism is peculiarly useful as applied to devices for perforating or for cutting oft' a well casing. For either-of such operations, only the substitution ofY suitable per- `forating or cutter carriers is necessary; and

form the desired service by virtue of continued rotation, and then be collapsed by merely being pulled upwardly. p

My invention is thus not limited to use in any specified tool, neither is it limited by they specifically described details of structure and operation asset forth in the foregoing specification for purposes of clarity of description; but on the other hand it is only to be v limited as expressed in the following claims, which are to be construed in their broad and ninclusive senses as well as in their restricted senses as literally expressed.

Although, for purposes of description, I have described the mandrel as being longitudinally .movable within the body, withouty or with relation to the body, itis understood that this mode of description of the mecha- 'rotative movements, especially when the tool 'isfin the hole, those rotative movements may mandrel movement in the operation of col-l lapsing the cutters-that is, when the mandrel is moved upwardly relative to the cutters so that the cutters then drop inwardly undei` themandrel cams. And even in that case, it is proper to view that relativemovement as a downward movement of the cutters on the mandrel rather than an upward movement of the mandrel with relation to the cutters. The view that the mandrel moves up between the cutters has, in this specification and the following claims,

ed because of the fact, in the specific embodiment of the invention herein described, 'that relative longitudinal movement is the movement that contracts the cutters. In the following relative upward movement of the cutters with relation to the mandrel, which is'` caused by the spring 27, it is more proper to view thatrelative movement as being an upward relative movement of the cutters on the mandrel, rather than the downward movement of)the mandrel between the Cutters.

The mandrel is mounted upon the drill stemand the spring cannot move the mandrel and drill stem, but can only move the body and cutters.

I daim; 1. In an expanding tool of the character described, the combination of a body, a cutter carrier mounted on the body to move lateralin the body movable` ly thereof, a mandrel both rotatively andi longitudinallywith relation to the cutter carrier, and a cam on the mandrel' adapted to engage and move the cutter carrier by virtue ofrotation and to be vmoved out of engagement with the cutter car` rier by virtue of relative longitudinal movement. p c

2. In anexpanding tool of the character described, the combination of a body, a cutter carrier mounted on the body to move laterally thereof, and a mandrel mounted in the body for longitudinal movement along and rotative movement about the longitudinal axis, and a cain on the mandrel adapted to engage and operate the cutter carrier in one longitudinal position of the mandrel and to be out of engagement with the carrier in another longitudinal position of the mandrel. I 3. In an expanding tool of the character described, the combination of a body, a cutter carrier mounted on the body to move laterally thereof, a rotary and longitudinally movbeen largely adoptand adapted by able mandrel within the body, a cutter carrier operating cam on the mandrel located behind the cutter carrier in one longitudinal position of the mandrel andram and located out of register withk the cutter carrier in another longitudinal position of the cam.

4. In an expanding tool of the character described, the combination of a body, a cutter carrier mounted on the body to move laterally thereof, a rotative and longitudinally movable mandrel within the body, a cam on the mandrel adapted by rotation when in one longitudinal position to engage the inner face of the cutter carrier and move the cutter carrier outwardly, stop means on the cutter carrier limiting such rotative movement of the cam to the a carrier is moved outwardly, and the cam being movable out of engagement with the cutter carrier. by longitudinal movement of the mandrel and cam.

In an expanding tool of the character described, the combination of a body, a cutposition in which the cutter ter carrier mounted on the body to move laterally thereof, a rotative and longitudinally movable mandrel within' the body, a cam on the mandrel adapted by rotation when in one longitudinal position to engage the inner face of the cutter carrier and move the cuttericarrien outwardly, stop means on the cutter carrier limiting such rotative movement of the cam to the position in which lthe cutter carrier is moved outwardly, and the cam being movableout of engagement with the cutter carrier by longitudinal movement of the mandrel and cam, the cutter carrier' being movable inwardly when the cam is so moved longitudinally, and a spring tending to move the mandrel longitudinally to engage the cam endwise against the cuttercarrier to hold it in its inward position.

6. In an expanding tool of the character described, the combination of a body, a cutter carrier mounted on the body to move laterally thereof, a rotative and longitudinally movable' means adapted by rotative movement to move the cutter carrier ,outwardly longitudinal movement to engage the cutter carrier to hold it in inward. position. Y

7. In an expanding tool `of the character described, the combination of a body, a cutter carrier mounted on the body to move laterally thereof, a mandrel in the body rotata-l ble about and movable along a longitudinal axis between two positions, a cam on the mandrel located behind the cutter carrier in one of said longitudinal positions of the mandrel andadapted in that position to move the rier and its stop means for further rotative movement out ot engagement with the carrier, and a spring acting between the cutter carrier and the mandrel to cause movementy of the parts back to their irst mentioned relative longitudinal positions when the cam is rotated out of engagement with the carrier.

8. In an expanding tool of the character described, the combination of a body adapted to be rotated about a vertical axis, a mandrel mounted in the body for rotation relative thereto about a vertical axis and also for movement vertically Vwith relation to t-he body between a lower position and an upper position, a cutter carrier on the body and Vmovable horizontally with relation thereto,

and a carrier operatingr cam on the mandrel positioned in the horizontal plane of the carrier when the mandrel is in its lower position and adapted to be raised Aabove the carrier when the mandrel is moved to its upper' position.

9. In an expanding tool `of the character described, the combination of a body adapted to be rotated about a vertical axis,-a mandrel mounted in the bodyifor rotation relative thereto about a vertical axis and yalso for movement vertically with relation to the body between a lower position and an upper position, a cutter carrier on the body and movable horizontally with relation thereto, and a carrier operating cam on the mandrel positioned in the horizontal plane of the carrierwhen the mandrel is in its lower position and adapted to be raised above the carrier when the mandrel is moved to its upper position, the carrier being movable to a position under the cam when the cam is in its upper position. c

10. In an expanding tool of the character described, the combination of a body adapted to be rotated about a vertical axis, a mandrel mounted in the body or'rotation relative 4thereto about a vertical axis and also-for movement vertically with relation to the body between a lower position and an upper position, a .cutter carrier on the body and movable horizontally with relation thereto, and a carrier operating camon the mandrel positioned in the horizontal plane of the carrier when the mandrel is in its lower position and adapted to be raised above-the carrier when themandrel is moved to its upper position, the carrier being movable to a position lunder the cam when thecam 1s 1n its upper wardly to and from the body, and a cam member within the body rotatable about and movable vertically Valong a-,vertical axis and adapted in one vertical position to engage and movethe swinging carrier and in another vertical position to be out of engagement with the swinging carrier.

13. In an expanding tool of the character described, the combination of a body rotatable about a central vertical axis, a swinging cutter carrier lmounted at one edge on a vertical axis on the body and having its free end adapted to swing inwardly and outwardly to and from the body, said swinging carrier having on its inner face toward the body a series of vertically spaced recesses, a mandrel mounted in the body and rotatable about and movable vertically along the axis ofthe body, and aseries of vertically spaced cams on the mandrel whose spacing corresponds with the spacing of said receses.

14. In an expanding tool of the character described, the combination of a body rotatable about a central vertical axis, a swinging-cutter carrier mounted at one edge on a vertical axis on the body and having its free end adapted to swing inwardly and outwardly to and from the body, the swinging end of said carrier being divided into a plurality of vertically spaced lingers, cutters carried at the swinging end of the carrier in the spaces between lingers, a mandrel in the body rotatable upon and vertically movable along the axis of the body, a spring tending to move the mandrel downwardly relative to the body, and a series of vertically spaced cam members on the mandrel and whose vertical spacing corresponds to the vertical spacing of said carrier fingers, so that in one vertical position of the mandrel the cam members are in horizontal registration with said ingers and in another position of the mandrel said cam members are in horizontal registration with the spaces between said fingers. f

15. In an expanding tool of the character described, the combination of a body, a cutter carrier mounted on the body to move laterally thereof, a rotatable cam mounted in the body and adaptedto engage the carrier and move it laterally outwardly away from the body, the carrier having a cam receiving notch into which the cam enters, said notch y lation to the mandrel and engagement with thecam serving to prevent further rotation of the cam and to prevent backward cam rotation by virtue of inward pressure exerted upon said carrier.

16. In an expanding tool of the character described, a mandrel adaptedfor attachment toa drill stem, a cutter carrying cage, a cutter carrier in the cage and movable in and out to andfrom the mandrel, the cutter carrier`being1movable longitudinallywith rethe mandrel being rotative with relation to cam on the mandrel adapted to engage the carrier in one longitudinal position and to -be out of such engagement in another longitudinal position.

17. In an expanding tool of the character described, a mandrel adapted for attachment to a drill stem, a cutter carrying cage, a cutter carrier in the cage-and movable in and out to and from the mandrel, the cutter carrier being movable longitudinally withrelation to the mandrel and the mandrel being rotative with relation to the carrier, a cam on the mandrel adapted to engage the carrier in one longitudinal position and to be yout of such engagement in another longitudinal position, and yielding means to move the cutter longitudinallywith relation to the mandrel.

v18. In an expanding tool of the character described, a vmandrel adapted for attachment to a drill stem, a cut-ter carrying cage, a cutter carrier in the cage and movable in and out to and from themandrel, the cutter carrier being movable longitudinally with relation to the mandrel andthe mandrel being rotative with relation to the carrier, a cam on the mandrel adapted*v to engage the carrier in one longitudinal position and to be outv of such engagement in another longitudinal position, and stop means on the carrier adapted to limit'relative rotation of the cam when the cutters are in their relative longitudinal position for cam engagement.

19. In an expanding tool of the character described, a mandrel adapted for attachment -to a drill stem, a cutter carrying cage, acutter carrier mounted on the cage and movablev in and out to and'from the mandrel, the cutter carrier being movable longitudinally with relation to the mandrel and the mandrel being rotative with relation to the carrier, the mandrel having a formation adapted by rotatlve movement to move the carrier outwardly andl adapted by longitudinal movement toengage vthe carrier and hold it in inward positlon.

20. In an expanding tool of the character described, a mandrel adapted for attachment to a drill stem, a cutter carrying cage, acutter carrier mounted on they cage and movable in and out to' and from the mandrel, the cut- 7ter carrier being movable longitudinally with relation to the mandrel andl the mandrel being rotative with relationto the carrier,

the carrier, and a rier being also movable eccentric face formed on said the mandrel having a longitudinally facing shoulder adapted to be selectively moved into and out of carrier engaging position by relative rotation.

2l. In an expanding tool of the character described, a mandrel adapted for attachment to a drill stem, a cutter carrying cage, a cutter carrier mounted on the cage and movable in and out to and from the mandrel, the cutter carrier being movable longitudinally with relation to the mandrel and the mandrel being rotative with relation to the carrier, the mandrel having a longitudinally facing shoulder adapted to be selectively moved into and out of carrier engaging position by relative rotation, and yielding means moving the carrier longitudinally relative to the mandrcl in a direction to move the carrier against saidA shoulder.

22. In an underreamer, a cage, a cutter carrier mounted in the cage and movable in and out, a. mandrel extending through said cageand mounted for rot-ary movement relative thereto, said mandrel being provided with eccentric shoulders for engagement with the inner edge of the cutter carrier, and a shoulder formed on said mandrel beneath which the carrier is adapted to engage when in its inward retracted position.

23. In an underreamer, a cage, a cutter carrier mounted in the cage and movable in and` out, a mandrel extending through said cage and mounted for rotary movement relative thereto,

said mandrel being provided with eccentric shoulders for engagement with the inner edge of the cutter carrier, a downwardly facing shoulder formed on said mandrel beneath which the cutter carrier is adapted to engage when in inward retracted position, and yielding pressure means for normally exerting upward pressure against said carrier.

24. In an underreamer, a cutter carrying cage, a cutter carrier mounted in the cage and arranged to move in and out therein, a mandrel associatedwith said cage, the cutter carvertically longitudinally with the reference to said mandrel, an mandrel for en-` gagement with the inner edge of said carrier, and means on said mandrel and carrier for locking the latter against vertical longitudinal movement when in its'inner retracted position.

v 25. In an underreamer, a cutter carrying cage, a cutter carrier mounted in the cage and arranged to move in and out therein, a mandrel associated withsaid cage, the cutter carrier being also movable vertically longitudinally with) reference to said mandrel, an eccentric face `formed, on said mandrel for engagement with the inner edge of said carrier, means on said mandrel and carrier for locking the latter against vertical longitudinal movement when in its inner retracted position, and yielding pressure means arranged within said cage beneath said carrier.

26. In an underreamer, a cutter carrying cage, a cutter carrier mounted in the cage and movable inwardly and outwardly therein, a mandrel extending into said cage and arranged to rotate therein, the cutter-carrier being also movable longitudinally with rela.- tion to said mandrel, means on said mandrel for engaging and projecting the cutter carrier when said mandrel is rotated, and means on said mandrel and carrier for locking the latter in its inward retracted position.

27. In an underreamer, a cutter carrying cage, a cutter carrier mounted in the cage and movable ,inwardly and outwardly therein, a'

mandrel extending into said cage and arranged to rotate therein, the cutter-carrier being also movable longitudinally with relation to said mandrel, and means on said mane drel and carrier whereby the latter is projected upon relative rotary movement of said mandrel and whereby saidcarrier is locked Y against vertical longitudinalvmovemcnt when retracted. Y

28. In an expanding tool of the character described, a mandrel adapted for attachment to a drill stem, a cutter carrying cage, a cutter carrier mounted on the cage and movable in and out to and from the mandrel, the cutter carrier being movable longitudinally with relation to the mandrel and the mandrel being rotative with relation to the carrier, the mandrel having a formation adapted to move the carrier outwardly by virtue of relative movement between the mandrel and carrier, and the mandrel also having a longitudinal facing shoulder adapted to be selectively moved into and out of carrier engaging position by relative rotation.

29. In an expanding tool of the character described, the combination of a cutter carrying body, a cutter carrier mounted on the body to move laterally thereof, a rotatable cam mounted in the body and adapted by rotation relative to the carrier to move the carrier outwardly, and yielding means tending to move the carrier outwardly.

v30. In an expanding tool of the character described, the combination of a cutter carry- 4,

ing body, a cutter carrier mounted on the body to move laterally thereof, a rotatable cam mounted in the body and adapted by rotation relative to the carrier to move the carrier outwardly, and yielding means independent of the cam acting to move the carrier outwardly.

In witness that I claim the foregoing I have hereunto subscribed my name this 17th day of January, 1928.

LAWRENCE S. CAMPBELL.

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