US2698737A - Core drill - Google Patents

Description

C. A. DEAN CORE DRILL Jan. 4, 1955 Filed Feb. 24, 1953 2 Sheets-Sheet l FIG ATTORNEY Jan. 4, 1955 C. A. DEAN 2,698,737

CORE DRILL V Filed Feb. 24, 1953 2 Sheets-Sheet 2 x .f /l/l/ 'y INVENTOR cHALEs A. DEAN ATTORNEY United States Patent() CORE DRILL Charles( A. Dean, Los Angeles, Calif. Application February 24, 1953, Serial No. 338,401 7 Claims. (Cl. Z55-72) This invention relates to core-drills for earth samples,

particularly to improved core heads for such drills.

The core drill of today is a cylindrical drill, rotated by rotation of a long string of pipe. These rotary drills operate deep in the earth, with the cutter head often a mile or two down in a bore hole. The drill cuts under great pressure from the weight of such a length of pipe and cuts through various earth formations. Yet the core sample must be representative, accurate and unmutilated.

The core head in these drills comprises an outer cylinder and cutters at the bottom to carve around a central core as the drill is rotated and lowered. The drill head contains also an inner hollow cylinder into which the core sample feeds as the drill works downwardly. The inner and the outer cylinders are movable vertically with respect to each other, while core dogs grip or release the 4earth sample by this movement of these core barrels.

These core dogs project into the core through openings in the inner barrel and are forced into the core or withdrawn as the outer barrel is raised or lowered. This raising and lowering occurs relatively often in normal operation of the drin.

The present invention is directed to the construction andv arrangement of the core head and core Vdogs that contain the earth sample. Previous faults in these structures have resulted in breaking or marring the core sample and in severe wear and breakage in the drill structures themselves. Many of these diiculties rest on failure to maintain the dogs and the core head in alignment so as tol minimize the effects of wear. Worn dogs often fail to withdraw cleanly from the core as the drill works up and clown in drilling. Such faults may become worse as the drill is used. For example in some forms of core drills in which the dog was intended to move freely in all directions, the shank or point became worn by contact with the wall of the core barrel and then bent or broke easily. Likewise, apertures in the wall of the core barrel, through which the dogs project, become worn out of alignment and to eccentric shapes. Such faults multiply worn parts and promote erratic and mutilating action of the core dogs on the earth sample. Debris accentuates such results as it clogs the various core barrel guides and operating elements. Accumulating mud stops easy movement of core barrel and dogs and adds to wear and breakage.

Analysis of many cases shows that undue play and `accentuated wear have centralized near the base of the core dog shank. This area receives severe forces of friction and wear between the wall of the core barrel land the shank of the core dog as the dog is thrust repeatedly into the earth core during drilling. This diiculty is aggravated when the inner barrel moves erratically or sluggishly, as sometimes happens when guiding splines between the inner and outer core barrels are worn or become clogged.

Purposes of this invention are to improve the co-action between core-dog and core-barrel of an earth drill, to provide more dependable action and Vless wear of the core-dogs, and to assure positive alignment and seating of core barrel down around the. earth core sample. Particular purposes are to overcome wear or clogging of splines between inner and outer core-barrels, to relieve core-dogs of undue stresses from misalignments of core barrel, and to relieve the dogs of undue wear from hang.- ing of the barrel above the core. bottom. A further object Vis. to accomplish these benefits by means that are simple to manufacture, assemble. and maintain. These and other Y 2,698,737 Patented Jan. 4, 1955 ICC objects will appear further in this speciiication and claims and be apparent in the accompanying drawings.

The drawings comprise:

Fig. I, a longitudinal View of the improved core-head of this invention, part of the head being cut away and shown in vertical section.

Fig. II, a longitudinal view partly cut away, similar to Fig. I but with the drill raised somewhat so that core dog and inner core barrel are relatively lower.

Fig. III, a cross sectional view inverted, looking up at a spring and spline assembly in the head, along the line 33 of Fig. I

Fig. IV, a cross sectional view, looking down upon a core dog assembly, along the line 4 4 of Fig. I.

Fig. V, a vertical view in perspective of an inner core barrel spline rib containing an upper spring support and a lower opening in the rib to house a wide core dog.

Fig. Vl, a perspective View of a wide core dog and axle.

This invention accomplishes benefits broadly in a core head that contains inner and outer core barrels. In such a head the inner barrel is mounted for limited relative movement up and down as the drill string to which the outer barrel is attached is lowered or raised. In this invention vertical spline ribs on the inner barrel carry relatively wide core dogs while resilient elements bear down on the inner barrel continuously. This downward bias serves to maintain freedom of action in the wide core dogs and the inner barrel and may serve further to regulate free flow of drilling fluid at the face of the core cut. Thus are minimized mutilation of core sample, wear of partis, sluggish action, and deposits of mud in the drill hea l More particularly, vertical spline ribs on the inner core barrel contain vertically short but relatively wide openings. Core dogs having commensurately wide Shanks extend through these wide openings from cylindrical bases seated in the outer core barrel. Resilient elements mounted within the outer barrel bear down on the inner barrel. Preferably a coil spring effects a downward bias, equalizes peripheral pressure and minimizes any pendulum-like swings within the outer barrel.

lFurther, in a preferred embodiment of this invention ports at the foot of the core head, arranged to direct drilling iiuid to the cutting face of the core sample, are Vented by free downward movement of the inner barrel. Pressure-release opening for the ports is biased by the resilient means that acts on the core dogs. Thus accumulation of mud is minimized. Free flow of drilling lluid continues without clogging the wide core dogs nor the core cutting face. The splined inner barrel and the core dogs tend to lioat more freely, to avoid side play, to wear longer, and to synchronize with ow of fluid to the core cut.

Various advantages and modifications will be apparent with detailed description of a preferred example of this invention.

Referring to a specific form of this invention, the drawings illustrate a core drill head l comprising an outer barrel 2 and aninner core barrel 3. Outer barrel 2 is located at its top to connect to a drill stem. The upper part of outer barrel -2 contains a recess 13 in its inner wall to house a heavy coil spring 4. This spring encircles and seats down on the inner barrel 3, preferably upon upper flanges 5 formed as grooved tongues extending outwardly from barrel 3. The spring 4 on flanges 5 may move up and down in housing recess 13 with the upper part of the spring bearing up against the top of the recess formed in outer barrel' 2. Thus spring 4 biases up against outer barrel 2 and down against inner barrel 3. Preferably this spring pressure is applied at the top of core barrel 3 and is uniformly distributed peripherally, as will be illustrated more fully. Inner barrel 3 is limited in down travel as ange 5 moves to abut against the oor of recess 13 as shown in Fig. il. When core barrel 3 rests on drilling bottom, spring 4 is compressed, as illustrated in Fig. l... Even when outer barrel 2 is lifted, as in Fig. II., downward thrust of spring 4 biases core barrel 3 down against bottom.

In operation the weight of the drillv string and outer barrel 2 keep spring 4 compressed, but this4 compression acting` upon core barrel 3 tends to overcomesluggishness and maintain free relative motion between inner barrel 3 and outer barrel 4. In this arrangement such action is rendered particularly effective by housing wide core dogs in vertical spline ribs on the inner barrel and, further, by regulating flow of drilling fluid through the head at the core cutting face. Broad benefits are to avoid nutilation of cores and to minimize impairment of core ogs.

As shown, adjoining walls of inner and outer barrels are splined together with wide spline ribs 6 on inner barrel 3. Splines 6 are arranged uniformly about the barrels as three splines are shown for example in Figs. III and IV. Splines 6 bear grooved flanges 5 at their tops to serve as spring seats to distribute downward pressure uniformly about core barrel 3. This pressure applied at the top of barrel 3 is most effective to stop pendulum-like swings of barrel 3 and thus to minimize play and wear between the various contacting parts. This stabilizing is desirable especially at the core dogs and at the bottom ports for drilling fluid. Stabilizing action of the spring upon the flange seats extends to the core dogs, so that closer housing clearances become practicable, and extends to the fluid ports at the core face so that clogging is avoided. Benefits appear in longer life and more dependable action of these parts.

Through the spline ribs 6 on inner barrel 3 are apertures 7 through which core dogs 8 project into the core space. This arrangement will be described further but it will be apparent that the dogs will project into a core in the barrel when the inner core barrel 3 is down (or outer barrel is up) and will be withdrawn when the inner barrel is up (or outer barrel is down) as when the core head rests on bottom. Tendencies of the core dogs to wedge in their housing if the core head swings to one side are minimized as the coil spring 4 on flanges 5 dampens unequal side thrusts.

With further reference to the core dog arrangements, this invention gains special advantages when a wide flat dog shank projects through a spline rib of the inner barrel. Such an individual core dog 8 is shown in Fig. VI. In preferred form, dog 8 comprises a large cylindrical base 9 substantially co-extensive with a wide shank 10.

Core dog 8 is mounted in outer barrel 2. Means within the outer barrel bear positively against the core dog base in any vertical movement to effect positively both core gripping and core release movements of the dog. The core dog base may be moved simply by contact with the upper and lower walls of its housing in outer cylinder 2, but preferably is pivoted, as by a hinge pin 11. As shown in Figs. I, II and IV, outer barrel 2 contains an aperture 9 to receive wide cylindrical base 9 of the core dog in radial alignment with complementa] aperture 7 through spline rib 6 of inner barrel 3. The upper wall of spline aperture 7 preferably slopes upwardly in the direction taken by the shank of core dog 8 when withdrawn into the spline. This minimizes wear on the shank and helps maintain alignment. Hinge pin 11 for cylindrical base 9 of the core dog rests in outer barrel 2 at the sides of outer aperture 9. Hinge pin 11 may be integral with base 9 and may rest in slots in barrel 2, but preferably cylinder 9 is perforated cross-wise and outer barrel 2 is perforated in alignment therewith to receive the ends of separate hinge pin 11. Thus the wide dog S may first be inserted into housing apertures 9 and 7 and then secured by cross-insertion of hinge pin 11 through the walls of outer barrel 2 and cylindrical core base 9. Then the dogs and their pin supports may be locked in by an enclosing shield 2 which is screw-threaded about the body of outer barrel 2, as shown in Figs. I and II and IV. This permits adequate shielding for drilling but easy assembly or replacement of the core dog parts. Also, this structure permits adequate flow of drilling fluid past the core dogs in the splines without clogging or impeding the core dogs.

With respect to drilling fluid, sufficient passage is found through and around the coiled spring 4 in recess 13 to reach channels or space 14 outside the inner core barrel to the bottom of the drill head. This is shown in Figs. III and IV.

In this description, the preferred form of resilient means pressing down on the inner barrel is described as an encircling coil spring, and its position as seated upon the same wide spline ribs as in their lower portion carry the relatively wide core dogs. But it will now be evident that other forms of resilient means, and other positions, can be provided to depress the inner core barrel housing for the core dogs. Such means should bear evenly around the inner barrel to maintain the splines in vertical alignment and to keep the core dogs, which extend through projections on the inner barrel, from undue wear or jamming.

Further observation of this invention shows that passageway radially for the core dog operation has many advantages when a wide dog shank moves through a spline rib and a wide cylindrical pivot base is mounted in a complemental recess inside the outer core barrel. Assembly is easy with the base placed near the outside circumferential area of the core head. The dog shank and point are guided and held by relatively extensive and strong walls inside the head. The dog shank is relatively massive and wide throughout, like its base. The hinge support is extensive but protected. The spline rib wall contacts the dog shank near its base and since the shank is wide the unit pressures are low. These broad areas of the core dog fitting against corresponding areas of the inner and outer barrels minimize play and wear. Guidance of dog shank and point is relatively positive and accurate; entrance and withdrawal of the dog-tooth into a core more nearly approaches an ideal curve because of this guidance. Downward spring bias on the inner barrel tends to rotate the core dog shank into the inner barrel or the core space. These conditions remain for relatively long periods of use, partly because of this form and housing and partly because pressure of the spring is effective over the considerable surface area afforded by the spline housing so that sticking of the dog is minimized. Sticking from one cause or another would hasten wear and misalignment of the dog and mutilation of the core sample. Moreover, the wide dog seated and housed as it is, substantially excludes deposits of drilling fluid about its surfaces. This exclusion also is favored by action of the spring at the top of the splines. The spring maintains the splines in vertical alignment in their channels. even under load. The spring also biases the inner barrel down even though the outer barrel may rise somewhat. This all tends to positive and dependable gripping of a core, even after core head and dogs have been in long use. One result is to minimize marring and breaking of an earth sample.

Spring 4 not only keeps the core dogs free and undamaged, but aids in washing the core face with drilling fluid and in keeping the inner core barrel free from clogging about the core. This is illustrated in Figs. I and II.

The bottom of inner barrel 3 may be provided with suitable cutters. as for example cutter head 15 threaded to barrel 3. Through this head extend ports 16. These ports extend from channel 14 in which drill fluid flows between the inner and outer barrels (see Figs. I, II, III and IV). Ports 16 divert drill fluid through the cutter head to the bottom of inner barrel 3 at the core face. Thus drilling fluid mav keep the core face and the inner barrel free during drilling, combatting any tendency for these ports to clog with drilling mud or debris. The force of drill fluid pumps at the top of the bore and the weight of the fluid and of the drill string impose pressure on the drill fluid to keep these inner ports open. This is facilitated by seating the bottom of outer barrel 2 upon the cutter head below ports 16 to close channel 14 to the outside, as shown in Fig. 1. Then all the force of the fluid promotes flow through ports 16 to the face of the core. However, this closing of conduit 14 by outer barrel 2 is against the bias of spring 4, which exerts upward pressure on barrel 2. Itwill be clear that the force of spring 4 may be selected or may be adjusted to exert such upward bias on outer barrel 2 as an operator desires for particular drilling conditions. Barrel 2 with the drill resting on bottom may close the outward vent to ports 16 with some excess of pressure or may float substantially in equilibrium with such drilling fluid pressure as is needed at the core cut. However, when the drill is lifted to any extent, outer barrel 2 at once rises from the cutter head and releases drilling fluid pressure at ports 16. This position is shown in Fig. Il. By this means, injurious pressure of fluid on the core face is avoided. Cutter head 15 or inner barrel 3 remains biased down by spring 4 at the top of splines 6 instead of tending to hang up in the drill head.

In practice, as the outer barrel 2 rises and falls, the alternate closing and opening or venting of the ports 16 tend to pulsate drilling iluid in the ports and to avoid accumulation of mud therein. In elfect a portion of the drilling fluid by-passes to keep the core cut clear but undefaced. This aids in avoiding sluggish action of the core barrels and between them and in permitting free action of the core dogs during the continual play desired in drilling. Thus free movements of the inner barrel and of the core dogs in the spline ribs are effected in synchronism with washing or freeing actions of the ports for drill fluid.

Certain subject matter of this application is found in my application Ser. No. 125,987 filed November` 7, 1949, now abandoned.

In accordance with the patent statutes, this invention has been explained with the principles thereof and their best mode of application to enable those skilled in the art to make and use the invention, but it will now be evident that variations and equivalents of the specific forms will be within this invention as dened in the appended claims.

I claim:

1. A core drill comprising an outer core barrel having an inner peripheral recess near its top, an inner core barrel vertically movable and having near the recess a seating surface for a spring, a coil spring mounted within the recess and upon the seating surface bearing down on the inner barrel, spline connection between the two barrels with spline ribs on the inner barrel apertured for introduction of a core dog into the barrel, a .vide core dog seated in the outer barrel and extending into the spline aperture, the spring and wide dog tending to maintain alignment of core barrels and dog during drilling.

2. A core drill comprising au outer core barrel, an inner core barrel vertically movable therein, a coil spring mounted between the two and bearing down peripherally on the inner barrel, spline ribs on the inner barrel apertured for introduction of a core dog into the barrel, a core dog extending into the spline aperture, the base of the dog being seated in the outer barrel, the dog base being perforated and the outer barrel being perforated for receiving a hinge pin, the spring and the dog tending to maintain alignment of core barrels and dog during drill- 1n g3. A core drill comprising an outer core barrel, an inner core barrel vertically movable therein, the outer barrel containing an inner recess near the top and the inner barrel having a ange extending into the recess for limited vertical play therein, a coil spring mounted between the barrels upon the ange and bearing down upon the inner barrel, spline ribs on the inner barrel apertured for introduction of a core dog into the barrel, a wide core dog extending into the spline aperture, the outer barrel containing an aperture for a core dog base and cross openings for a hinge pin, the core dog base being seated in the outer barrel aperture and perforated to receive a hinge pin in alignment with the cross openings, the spring and the wide dog mounting tending to maintain alignment of core barrels and dog during drilling.

4. In a core drill comprising an outer barrel, an inner core barrel vertically movable within the outer barrel, a spring mounted between the two barrels bearing down on the inner barrel and spline connection between the two barrels comprising ribs on the inner barrel, the combination of spline ribs containing a wide aperture therethrough for housing a wide shank of a core dog, with the outer barrel containing a wide recess complemental to the aperture for housing a wide base of a core dog, whereby a wide core dog base may seat in the recess housing and extend its shank therefrom through the spline rib aperture, and means within said outer housing positioned to bear positively against the core dog base in any vertical movement for effecting positively both core gripping and core release movements ofthe core dog.

5. A core drill comprising an outer core barrel recessed near its top, an inner core barrel vertically movable within the outer barrel, a spring housed in the recess and bearing down on the inner barrel, spline ribs on the inner barrel containing a wide aperture therethrough, a wide cornplemental recess in the outer barrel opposite the rib aperture, a wide cylindrical core dog base pivotally housed in the wide recess and having a wide shank extending into the rib aperture, and means within the dog base housing engaging the base in any vertical movement, for positively pivoting the core dog in core gripping and core release movements through the spline rib on relative vertical motions between the inner and the outer core barrels, the downward spring bias on the inner barrel tending to rotate the core dog shank into the inner barrel.

6. A core drill comprising an outer barrel, an inner core barrel vertically movable therein, spline ribs on the inner barrel containing an aperture therethrough, a core dog seated in the outer barrel and having a shank in the aperture in contact with the spline for core engagement on relative downward movement of the inner barrel, the inner and the outer barrels being spaced from each other from top to bottom to provide a conduit for drill iluid the inner barrel containing an opening therethrough near its bottom between said conduit and the core space constituting a port leading to the core-cutting face and a relief port for said conduit, the outer barrel comprising means to close and to open the conduit below said relief port as the inner barrel moves up and down respectively, and a spring seated between inner and outer barrel and bearing down on the inner barrel, whereby positive movement of the core dog by spline contact and operation of the relief port are effected in synchronism.

7. A core drill comprising an outer barrel, an inner core barrel vertically movable therein, spline ribs on the inner barrel containing an aperture therethrough, a core dog having a cylindrical base seated in the outer barrel and having a broad shank in the aperture, the spline contacting the dog shank near the cylindrical base, whereby the dog moves pivotally in the spline into and out of a core on relative vertical movement of the barrels, the inner and the outer barrels being spaced from each other from top to bottom to provide a conduit for drill fluid between the barrels, the outer barrel being adapted to seat upon the inner barrel near the bottom to form a closure for the conduit and adapted to lift therefrom to vent the conduit, the inner barrel containing an opening therethrough near its bottom above said outer barrel seat between said conduit and the core space constituting a diversion port from the conduit to the core-cutting face at the bottom of the drill, whereby drill nid diversion to the core face is relieved on lowering of the inner barrel, and a spring seated between the barrels and bearing down upon the inner barrel for downward bias of the inner barrel and of the spline, whereby free movement of the inner barrel and of the core dog are facilitated.

References Cited in the tile of this patent UNITED STATES PATENTS 643,082 Bullock Feb. 6, 1900 1,850,386 Dean Mar. 22, 1932 1,987,853 Howard et a1. Jan. 15, 1935 2,234,264 Lang Mar. 11, 1941

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