US2533259A - Cluster tooth cutter - Google Patents

Description

Dec, 2, 11950 H. B. WOODS ETAL 2,533,259

CLUSTER TOOTH CUTTER Filed June 2s, 1.946 4 Sheets-Sheet 1 HEN RY B. Woons FLOYDLSCQTT INVENTORS www ATTORNEY.

Dec. 1, 1950 H. B. WOODS ETAL 2,533,259

CLUSTER TOOTH CUTTER Filed June 2a, 1946 4 Sheets-Sheet 2 W I HENRYBWOODsT FLOYD. LSCOTT INVENTORS ATTQR N EY.

Dem 12,, 1950 woogs ETAL 2,533,259

CLUSTER TOOTH CUTTER Filed June 28, 1946 4 Sheets-Sheet 5 g 5 HENRYBWQUDS FLOYD Lmw INVENTOR5 ATTORNEY.

150 H. B. WOODS ETAL CLUSTER TOOTH CUTTER 4 Sheets-Sheet 4 Filed June 28, 1946 HENRY 5. Wows FLOYD L 5COTT INVENTORS ATTORNE Y Patented Dec. 12, 1950 CLUSTER TOOTH CUTTER Henry B. Woods and Floyd L. Scott, Houston,

Tex,

assignors to Hughes Tool Company,

Houston, Tex, a corporation of Delaware Application June 28, 1946, Serial No. 680,154

4 Claims.

Our invention relates to rolling cutters for rotary earth boring drill bits such as are employed in drilling wells for oil, gas, water and the like. The invention has particular application to the distribution and form of cutting projections or teeth upon said cutters.

It has been common practice to form the teeth on a cutter in annular rows, each row comprising cutting projections more or less evenly spaced throughout the full circle of said row.

' While drilling upon the bottom of a well bore the teeth are forced to penetrate the formation by superposed weight as the cutters roll and thus remove the material to be excavated.

In certain oil and gas fields where the for-mation bedding planes lie at a considerable angle with respect to the horizontal it is necessary to use considerably less weight on the drill bit than that weight regularly used in areas where the bedding planes lie more nearly in a horizontal direction. Under such light-weight conditions there is considerable lack of progress with cutters of common structure because too many teeth engage the formation to be out at any instant of rotation of the bit, which results in too great a distribution of the drill stem weight. To increase the pressure of each tooth on bottom it is oustomary to use a bit with coarse or widely spaced teeth for drilling in such formations; however, such teeth on a cutter tend to generate coarse pitched rock teeth on the well bottom which are strong and resist disintegration.

An expedient for breaking down the coarse pitched rock teeth is to use unevenly spaced teeth in a row which is discussed in Patent No. 1,896,251. Such a bit is satisfactory on certain formations where the teeth perform in the manner indicated in the patent whereb the tendency to generate a rock gear is overcome. In other formations, however, the cutter will skid forwardly, or rearwardly, and thereby form a rock gear. Such operating characteristic not only defeats the purpose of the uneven spacing but also introduces additional wear as a result of the skidding without any commensurate cutting action.

An object of the invention is to provide drill cutters having cutter teeth that are so constructed and arranged that maxi-mum penetration is obtained therefrom, with a given weight applied to the bit.

Another object is to provide a rotary cutter drill bit where the spacing of certain successive teeth thereon approximates the sum of the spacing of the remaining teeth.

It is also an object of the invention to provide a rotary cutter drill bit capable of drilling both hard and soft formations at a maximum rate with light weight applied thereto.

Another object is to provide a rotary cutter type of drill bit which is capable of drilling straight hole at rapid penetration rates.

Another object of the invention is to provide, on a rock cutter, teeth which are arranged in clusters in circumferential rows with adjacent teeth in eachcluster having a relatively small pitch, so that the rock gear formed on bottom will likewise be of a small pitch and hence readily disintegrated by the cutting action of the cutter.

Another object is to stagger the clusters of teeth on the several rows on the cutter so that the number of clusters on the cutter engaging the bottom of the hole at any time will be such as to concentrate the bit load on a few teeth.

It is also an object of the invention to provide a cluster of teeth which are of such a pitch relative to each other that the combined pitches of all the clustered teeth is less than the span of the blank space on the cutter between the ends of the cluster of teeth.

Other and further objects of the invention will be readily apparent when the followingdescription is considered in connection with the accompanying drawings wherein:

Fig. 1 is a perspective view of a drill bit constructed in accordance with the invention. The bit is shown in inverted position to illustrate the arrangement of the clusters of teeth. 1

Figs. 2, 3 and 4 are plan views looking at the apexes of the three cones of the bit in Fig. 1, and illustrate the arrangement of a full row of heel teeth with all the inner rows clustered.

Figs. 5, 6, and '7 are similar plan views of the three cones showing a somewhat modified arrangement where the heel row is also clustered.

Figs. 8, 9 and 10 are likewise similar plan views looking at the three cones of a bit where all the rows are clustered.

The inverted bit body 2 of 1 has the threaded pin 3 by which it is connected to the drill collar or drill pipe. This body has three downwardly projecting legs 4 which are spaced apart and carry a suitable bearing structure by which the cones, I, 8 and 9 are rotatably supported for engagement with the earth formation.

Each of these cones is made up of the substantially conical body I0 having a peripheral surface ll. Projecting outwardly from the surface II is a row of heel teeth l5 made upoi individual teeth I6, which are spaced around the periphery of the cone. Adjacent heel teeth are joined together in pairs by circumferential webs I 8, there being gaps 20 between successive web sections. Such webs assist in maintaining the bore of the hole and sever the rock teeth which tend to form and join the well bottom to the side wall of the bore. In order to prevent the webs I8 from tracking, an odd number of heel teeth is provided and hence one of the teeth 22 (Fig. 2) has a short web 23 with a gap on either side thereof.

A space disposes the next row 3| of teeth inwardly from the heel teeth. This row 3| is made up of a cluster of teeth all of which are preferably, but not necessarily, of the same size and pitch. It should be noted that this cluster 32, as best seen in Fig. 2, extends only part way around the cone and leaves a blank space 33 between the ends 34 and 35 of the cluster. The cluster may extend for somewhat more or somewhat less than half the circumference of the cone. With a construction of this sort, for half of a revolution of the cone, the row 3| is on bottom while for the other half of a revolution this row is not on bottom and weight that was carried by this row is shifted to other clusters of teeth on the cone such as the next inward row 31, which is made up of the cluster of teeth 38. It will be noted that the cluster 38 is staggered with respect to the cluster 32 and is disposed longitudinally toward the apex of the cone. The row 31 also extends for a portion of the circumference of the cone.

The cone 1 is arranged to cut the center portion of the hole with a spear point 46, which has been provided with the surfaces 4| and 42 diverging from the apex of the cone. A skirt 43 about the point All cooperates therewith to bring about necessary cutting action to completely disintegrate material at the center of the hole.

A feature of the cluster arrangement of the teeth is that the combined pitch of all the teeth will approximate the remaining space 33 between the end teeth of the cluster. Of course, if the cluster were half a periphery then the combined pitch of all the teeth would equal the space 33. It is intended that variation from this equal distribution of pitch may be had as illustrated in the drawing.

The cone 8, as seen in Figs. 1 and 3, is constructed somewhat similar to the cone 1 except that in the heel row 45 a cluster 46 of longer teeth 41 has been provided. These longer teeth are interrupted by the spaces 48 in the central portion thereof, as seen in Fig. 3. The next inwardly spaced cluster 50 on this cone is staggered with respect to the heel cluster 46. This cluster 50 is, of course, spaced inwardly with respect to the row 45. The innermost cluster 5| on the cone 8 is staggered with respect to the row or cluster 50 and is also spaced longitudinally along the cone.

The cone 9, best seen in Figs. 1 and 4, has the heel row constructed quite similarly to the heel row 15 of the cone 1, in that it is made up of the combination heel and web teeth IS. The next inner row 56 on the cone 9 also constitutes a cluster while the cluster of the innermost row 51 is staggered with respect thereto.

The rows or clusters of teeth on the cones 1, 8 and 9 to which reference has just been made, are so spaced longitudinally along the cones and with respect to each other that they are shown adapted to interfit; that is, each row or cluster of teeth is so placed on its cone that it lies between clusters of teeth on the adjacent cones. It is to be understood, however, that the invention is not limited to cones having inerfitting teeth.

In view of the fact that each cluster of teeth comprises about half of a circumferential row it seems obvious that while the blank space between the ends of the teeth in any cluster is facing the bottom of the hole the weight must be carried by the teeth in other clusters on the cone. It is obvious, therefore, that the weight is shifted back and forth from one cluster to another as the cutters roll so that the weight is concentrated on the limited number of teeth which are engaging the well bottom.

Figs. 5, 6 and '7 show three cones 58, 59 and 60, respectively, embodying the invention on which the heel teeth are connected in pairs by the circumferential webs as on the cones 1', 8 and 9. The cluster arrangement has been extended to include the outermost rows of teeth, however, so that all the rows are clustered, shown at 8| in Fig. 5, 62 in Fig. 6, and B3 in Fig. 7.

Figs. 8, 9 and 10 show three cones 10, 1| and 12, which are quite similar, respectively, to the previous set of cones 1, 8 and 9, shown in Figs. 1 to 4, inclusive, and are like the cones 58, 59 and 60, shown in Figs. 5 to 7, inclusive, except that the webs on the heel row cluster 15 of each of these latter cones, has been omitted, so that the straight longitudinal teeth are provided. Such an arrangement may be of advantage in some types of formation.

In Fig. 8 the spear point 16 has two teeth 11 on one side thereof, which form a miniature cluster, and the cone 18 also has the clusters 18, 19 and 15 spaced longitudinally along the cone. The cone 1| (Fig. 9) has the clusters 80, 8!, 82 and :5 in staggered relationship longitudinally of the cone; also the cone 12 (Fig. 10) has the clusters 83, 845 and 15 spaced longitudinally therealong.

In actual operation it has been found that bits constructed in accordance with the foregoing description not only cover bottom completely but penetrate the formation at rates in excess of the rates obtained from cutters having a full complement of teeth. A well drill cone of the type described generally makes between 1.1 and 1.6 revolutions per revolution of the drill head. Because of this a cluster of teeth contacts bottom at a different place from which it contacted on the previous revolution. Thus each annular space contacted by the cluster of teeth is completely covered in a few revolutions of the bit. For example, on a particular bit made in accordance with this invention the cones made 1 revolutions per revolution of the drill head and bottom was completely covered in three revolutions of the bit. A satisfactory rate of penetration may be obtained with the bit while applying a much less weight to the bit and, of course, the lesser the weight applied to the bit the straighter will be the hole being drilled, so that in some instances the bit may be utilized effectively for the straightening of crooked hole, or maintaining straight hole in regions Where the tendency is for deviation from the vertical.

While the foregoing description refers specifically to embodiments of the invention in bits of the cone type it is to be understood that the invention is not confined to the cone type of cutter as the invention broadly contemplates a bit having rolling cutters and in which the weight for effecting cuttingaction is concentrated and applied in a manner to obtain the maximum penetration from the normal and intended use of the bit.

What is claimed is:

1. A cone type well drill including a head, three roller cones thereon, each of said cones having a plurality of segmental circumferential clusters of cutter teeth, with adjacent clusters longitudinally staggered on the cone, the spacing between successive clusters on the cone being suflicient that,- during rotation of the cones, the clusters of each cone move in a path interfitting the paths of travel of spaced clusters on the two adjacent cones.

2. A roller cone type well drill having a body, three roller cones thereon, a plurality of cutter teeth on each cone, the teeth being arranged in clusters in circumferential arcs on the cone with the clusters spaced longitudinally of the cone and staggered circumferentially, each cluster approximating half a cycle, successive clusters on a cone being spaced a distance that, during rotation, clusters of the adjacent cones interfit therewith.

3. A roller cone type well drill having a body, a plurality of roller cones thereon, a plurality of cutter teeth on each cone, the teeth being arranged in spaced, staggered clusters in circumferential arcs on the cone, and a circumferential REFERENCES Gimp The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,896,251 Scott Feb. 7, 1933 1,905,066 Scott Apr. 25, 1933 2,147,926 Scott Feb. 21, 1939 2,292,036 Behnke Aug. 4, 1942 2,363,202 Scott Nov. 21, 1944 2,370,070 Phipps Feb. 20, 1945

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