US 2025261 A
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Description (OCR text may contain errors)
.1.- A. ZUBLIN DRILL BIT.
Dec. 24, 1935.
Filea May 20, 1955 N U D U Z. A m
INVENTOR BY um ALITQRNEY Patented Dec. 24, 1935 UNITED sl'rlvnzs PATENT "OFFICE -80laims.
The present invention has to do generally with rotary well drilling bits comprising a shank with a cutter rotatably mounted on the lower end of the shank; and the present improvements are concerned more especially with the mud-water or fluid circulation passages in bits of this type.
Great savings in well drilling costs can be accomplished by making a bit which will drill aster, thus savii'ig on the overall time, or one 1- that will drill longer without replacement-thus reducing the number of round trips made to replace worn-out bits. As the time required to replace a worn-out bit is non-productive and becomes proportionately more important in deep holes, longer performance of the bit is particularly to be desired.
As an aid in drilling, fluid is circulatedbetween the top and bottom of the hole tocarry out the cuttings; however, the stream of entering fluid is often of such character as to reach only a part of the hole bottom, with the result that rem val of the cuttings is slow and progress of the b t is impeded by a gathering of cuttings on the botom.
This circulation fluid is flowed around the cutter bearing to lubricate the bearing and keep it cool, but the fluid normally carries such a large amount of abrasive material that the bearing is subject to considerable scour and wear from foreign material in the circulation fluid.
It is therefore a general object of my invention to provide a bit which introduces circulation fluid into the well bottom in such a manner as to carry away the cuttings as fast as they are dug, thus permitting the bit to always work on a new face ball up the bit and slow down progress.
It is also an object of my invention to separa of the hole .without hindrance from cuttings whic out the abrasive material from a portion of the v circulation fluid so that this "cleaned portion will be'a lubricating medium which will not scour,
or wear the bearing surfaces. A further object is to insure positive and adequate lubrication of the bearings at all times with circulation fluid free from abrasive material.
. These objectsare attained in a bit characteristic of my invention by providing a tapered section to the circulation passage in the bit shank, and providing in the cutter wall a discharge aperture which is smaller than the discharge endof'the tapered section to the shank passage. The wall of the cutter thus projects into the peripheral portion of the fluid stream,a portion that is relatively free of abrasive material, and the fluid striking the cutter wall is partially diverted upits bearing in elevation; and,
wardly to flow around the bearing, and the remainder is diverted downwardly to cause the that carries incoming fluid to all parts of the hole bottom.
How these and other objects are attained will best be understood by reference to the following description and the accompanying drawing, in which:
Fig. 1 is a side view of an assembled bit showing 0 the cutter and the lower portion of the shank in vertical section; 9"
Fig. 2 is a fragmentary view of the lower end of the same bit, showing the cutter in section and Fig. 3 is a fragmentary vertical section of a variational form" of bit.
I The construction of the drill bit shank and cutter'bearing illustrated in Figs. 1 and 2 is set forth in detail in my copending application .Ser. 20 No. 741,913, entitled Improvements in drill bits,-
filed August 29, 1934, to which reference may be made for details, so the structure of these parts will be only briefly described. Fig. 1 shows a internal cavity adapted to receive the shank 35 bearing. The internal surfaces of body 20 are complementary to the surfaces of bearing l5 so that the cutter .rotates,.relative to the shank, about axis AA. The exterior of the cutter body is provided with a plurality of soil cutting 40 blades l9 which may be of any suitable shape.
Shank ll terminates in a cylindrical portion that provides surface 2| which is part of bearing l5. At the end of this cylindrical portion, the shank is recessed and screw-threaded to re- 45 ceive a cone-shaped thrust bearing or pin 22 which screws into the recess. The upper portion of the thrust cone has a cylindrical surface at 23 of the same diameter as and in continuation of surface 2|, these cylindrical surfaces forming 50 that portion of bearing l5 adapted to take radial thrust. The lower portion of the thrustcone is formed with a downwardly disposed frustoconical surface 24 which merges with cylindrical surface 23 above it and'which is adapted to re- 55 ceive the axial thrust of the cutter along axis A-A. The shank may be made with the thrust bearing as an integral part, but the cone-shaped bearing is preferably made detachable so that it can be easily replaced when worn. 5 1
Cutter I8 is placed upon the bearing by axial movement, and is held against removal by suitable locking means which includes a plurality of balls 28 within an annular ball holding channel formed partly by concave groove 29 in bear-' ing I5 and partly by a complementary annular groove 30 in body 20. These balls are of a diaameter somewhat less than the total width of the channel so that they do not act as bearing elements but when in place prevent movement of the cutter longitudinally of the bearing, except as permitted by the elongation of groove 30. It will be noticed that in Fig. 1 groove 30 extends above balls 28, thus permitting the cutter to move down on the hearing from the position of Fig. 1 to the position of Fig. 2 when a gap is formed at 32 between the thrust surfaces.
In order to permit introduction of balls 28 into the channel, and also their removal therefrom, there is provided a notch (not shown) in the rim of the cutter and a recess 33 in the side of the shank, through which'the balls may freely pass when the notch and recess are in registry. The balls are held within the channel by filling the lower end of recess 33 with plug 34 which is held in place by a lock screw, as is described in detail in my said copending application.
Circulation fluid is carried lonigtudinally of the bit through-an internal fluid passage and discharged into the well. This passage comprises portion 36 in the shank body, from which a part of the fluid is discharged through nozzle 31 to clean the upper part-of the cutter, and the portion in the cone-shaped bearing 22, this latter portion being composed of an upper section 38, which is preferably straight and cylindrical, and a lower section 39, which is preferably conical. Terminal section 39 diverges outwardly in the direction of stream flow, so that the larger end forms, within the cutter bowl, a discharge orifice from which the main stream of circulation fluid is discharged.
The cutter body 20 is provided at the bottom with discharge aperture 42 which is alined with orifice 40 to pass the circulation fluid into the well bore. Aperture 42 is preferably circular, as is orifice 40, but is of a smaller diameter, though not smaller than the diameter of section 38. Also, it is preferable that the axes of passages 38, 39 and of aperture 42 coincide with axis A-A.
With this construction, the cutter body forms an annular wall around the periphery of the discharge orifice, and this wall is so disposed that it has a face lying obliquely to the stream flow and in the path of the peripheral portion of the stream issuing from the orifice. Hence, the peripheral portion of the stream will strike against this annular wall at 44, formed here by the wall of the cutter body.
Circulation fluid is forced through the shank passage under high pressure and moves at a relatively high velocity, and advantage is taken of these characteristics to separate out the heavier particles of abrasive material carried by the fluid stream from a portion of the circulation fluid. As the circulation fluid moves through the terminal conical section of the passage, the pres sure upon theliquid causes it to keep the conical passage completely filled at all times, so that their inertia, tend to continue moving straight ahead after leaving passage 38 so that these heavier particles in the main pass through aperture 42 without striking the cutter body. Since the particles of foreign matter tend to move parallel to the axis of conical section 39 and not radially, the fluid adjacent the wall of this terminal section is relatively free from foreign particles and abrasive material; and it is this peripheral portion of the stream which strikes against the body wall at 44 surrounding aperture 42.
After striking against the cutter wall, a portion of this fluid is diverted upwardly to flow around the bearing to lubricate it and keep it cool. Entrance of the water to the space between v the cutter and thrust pin bearing surfaces is facilitated by the limited longitudinal play of the cutter body along the bearing. As drilling progresses, the irregularities in the bit movement will intermittently cause a gap to be formed at 32 between the two bearing surfaces, and 5 lubricant will be very easily introduced at this time. The lubricant will then work its way up along the cylindrical surfaces of the bearing, since the cutter fits with sufficient clearance to permit lubricant to move through the bearing. It will be noticed that the lubricant is supplied to the bearing evenly around the entire circumference of discharge oriflce and is not concentrated at only one or two points.
After striking the cutter wall around the dis- 5 charge oriflce, fluid, in order to flow between the cutter and its bearing, must change its direction of motion by substantially more than 90, since the lubricant is flowing generally upwardly about the bearing. The fluid for lubrication is diverted 40 through an angle greater than 90, but there is a tendency for the momentum of any heavy particles to deflect the particles off the cutter walls l into the stream passing out .aperture 42, being thus deflected through an angle less than 90. 45
Hence there is a reverse flow effect, tending further to separate out abrasive particles from the lubricant. In this way the bearing is positively and adequately supplied at all times with lubricating fluid practically free of abrasive particles and the feed is accomplished in such a manner as to eliminate scour or erosion, with the result that the bearing wears more slowly and, has a longer life than is possible with the conventional fluid passage construction. Another important result attaches to placing a part of the cutter wall inthe path of the peripheral portion of the stream issuing from section 39, since a portion of the water striking the cutter is deflected across aperture 42 and strikes the .action causes the stream to spread out in a much wider cone than would result from the use of terminal section 39 alone. The stream thus entering the well reaches all parts of the well bottom, violently churning the fluid in the-well,- and lifting the cuttings oil. the bottom into the upwardly moving current which carries the cuttings out of the well. The turbulence and agitation of the fluid at the bottom is so marked that as it rises around the body of the cutter, the cutter teeth are washed clean and kept free of accumulations which ball up the cutter.
In this way the cutter is continually kept clean and in the best .cutting condition, and-the well 76 bottom is kept free of cuttings which prevent the cutter blades from effectively reaching the formation in order to remove further cuttings. As a result of removing the cuttings as fast as they are formed, the digging speed of thecutter has been greatly increased and the life of the blades has been increased because they are no longer worn out by continual contact with cuttings once removed from the well walls.
Fig. 3 shows a variational form of bit in which the shank end is formed with a cutter bearing I5,
as described, on which the cutter 20a is rotatably mounted. The construction of the fluid circulation passages diifers from that previously described only in that the entire passage 50 in the cone-shaped cutter bearing 22 is straight walled and of the same size as orifice 40 which is larger than aperture 42. As already explained, the stream of fluid is discharged from orifice 40 and the peripheral portion of the stream strikes the cutter walls to divert around the bearing a portion of the fluid to act as a lubricant. The reverse flow effect tends to separate out foreign matter, and the turbulent flow through aperture 42 spreads out the stream into a wide cone which 4 reaches all parts of the bottom.
Since various changes in shape and construction of parts may be made without departing from the spirit and scope of my invention, it is intended that the foregoing description be considered as illustrative of rather than restrictive upon the broader claims appended hereto.
I claim as my invention:
1. In a well drilling bit, the combination of a shank formed with a cutter bearing; a bowlshaped cutter rotatably mounted on the bearing with clearance to receive a lubricant around the cutter bearing; and a circulation passage extending through the shank for discharging a stream of circulation fluid into the well and having a discharge orifice, the walls of said cutter project- .cutter bearing; said shank having a circulation passage extending through the shank to discharge a stream of circulation fluid into the well and terminating in a tapered section of which the larger end forms a discharge orifice, and the walls of said cutter projecting into the path of the peripheral portion of the discharged stream to divert between the cutter and its bearing a portion of the stream.
, 3. In a well drilling bit, the combination of a shank formed with a cutter bearing; a bowlshaped cutter rotatably mounted on the bearing; a circulation passage extending through the shank for introducing circulation fluid into the well and terminating in a conical section of which the large end forms a discharge orifice; and a circulation aperture in the cutter positioned coing a fluid circulation passage extending therethrough to a discharge orifice, and the walls of said cutter about the orifice projecting into the peripheral portion of the discharge orifice whereby the peripheral part of the discharged stream of circulation fluid is by deflection forced to flow between the contacting surfaces of the cone bearing and cutter.
5. In a well drilling bit, the combination of a shank, a detachable cone-shaped cutter bearing, and a bowl-shaped cutter rotatably mounted on said cone bearing with clearance to receive lubrication between the contacting surfaces of the cone bearing and cutter; the cone bearing having a fluid circulation passage extending therethrough and terminating in a tapered section that forms a discharge orifice, and the walls of said cutter about the orifice projecting into the peripheral portion of the discharge orifice whereby the peripheral part of the discharged stream of circulation fluid is by deflection forced to flow between the contacting surfaces of the cone bearing and cutter.
6. In a well drilling bit, the combination of a shank formed with a cutter bearing; a bowlshaped cutter rotatably mounted on the bearing;
.a circulation passage extending through the shank for introducing circulation fluid into the well, said passage comprising a terminal conical section of which the large end forms a discharge orifice, and a straight cylindrical section immediately preceding the terminal conical section; and a circulation aperture in the cutter positioned co-axially ofthe conical discharge orifice and having a diameter smaller than that of the discharge orifice.
'7. In a well drilling bit, the combination of a shank formed with a cutter bearing; a cutter rotatably mounted on the bearing with clearance to receive a lubricant around the bearing; a main circulation passage extending through the shank for discharging a stream of circulation fluid into the well and having a main discharge orifice; and the walls of the cutter projecting into the path of the peripheral portion of the main discharge stream to divert between the cutter and itsbear- 55 ing a portionof the stream. 8. A well drilling bit having a main fluid passage discharging a stream of circulation fluid into the well, said passage having one section which gradually increases in area in the direction of stream flow and a second'section of smaller area than the larger end of said first section following said first mentioned section in the direction of stream flow, and a fluid passage opening to the larger end of said first section to withdraw fluid for lubrication from the periphery of the main circulation fluid stream.
JOHN A. ZUBLIN.