US2340492A

US2340492A - Cutting teeth for well drills

Info

Publication number: US2340492A
Application number: US357725A
Authority: US
Inventors: Floyd L Scott
Original assignee: Hughes Tool Co
Current assignee: Hughes Tool Co
Priority date: 1940-09-21
Filing date: 1940-09-21
Publication date: 1944-02-01
Anticipated expiration: 1961-02-01

Description

scoTT I 2,340,492

FOR WELL DRILLS Feb. 1, 1944.

CUTTING TEETH Filed Sept. 21, 1940 INVENTOR.

fig 0'1 600 W E M 1 ATTORNEYS.

Patented Feb. 1, 1944 CUTTING TEETH FOR WELL DRILLS Floyd L. Scott, Houston, Tex., assignor to Hughes Tool Company, Houston, Tex., a corporation of Delaware Application September 21, 1940, Serial No. 357,725

Claims.

My invention relates to the forming of the cutting teeth upon well drills and more particularly the type of well drill employing two or more approximately conical shaped cutters. Such well drills are ordinarily termed cone drills" in the field and the cutters are referred to as cones.

It is an object of this invention to provide a tooth formed upon the cutting surface of the cone which will more effectively engage and cut away the formation being drilled.

It is a further object to mount the cutters upon which the teeth are placed in such manner that the teeth will have a plowing action on the well bottom and thus more effectively disintegrate the material.

It is a further object of the invention to space the teeth upon the cone surface in such manner as to provide space into which the material being cut maybe displaced and thus more readily Washed away by the flushing fluid.

It is a further object to provide a cutting tooth which may engage the formation with a sharp cutting edge and more readily penetrate into the bottom of the hole.

For a better understanding of the invention reference is made to the drawing herewith wherein,

Fig. 1 is a top plan view of the bottom of the hole showing somewhat diagrammatically the position of the cutters upon the bottom.

Fig. 2 is a view showing one of the cutters in side elevation positioned upon the bottom of the hole, and having teeth embodying my invention.

Fig. 3 is a perspective view of a cutter tooth embodying one form of the invention; and

Fig. 4 is a similar perspective view illustrating a slightly-different form of cutting tooth.

Well drills embodying cutters of the general character upon which my invention is applied are well known in the art. A cutter such as shown at A is mounted rotatably upon a shaft l projecting inwardly and downwardly from its support upon a drill head 2. When an approximately conical shaped cutter is mounted in this position the conical surface is presented downwardly toward the well bottom and tends to disintegrate material as the cutter is rolled upon the bottom of the hole.

The cutters are normally provided with a row of heel teeth 3 adjacent the base of the cone, this row of teeth being relatively long and having the teeth chisel shaped, with a cutting crest 4 thereon. Between the row of heel teeth and the apex are teeth 5 which cut the bottom of the ldiolfi adjacent the inner axis of rotation of the In previous forms of well drills of this character it has been common to offset the axis of rotation of the cutter from the axis of rotation of the drill. This offset has been slight and in the amount of only a fraction of an inch. This offset of the cutter axes from a true radial position has been employed to get a slight deviation from a true rolling motion of the cutters. The teeth are thereby given a slight scraping or twisting action on the bottom, which assists in disintegrating the material.

In the present invention the axes 6 of the cutters have been swung around until they are tangent to a. comparatively large circle having a diameter of two or three inches. This exaggerated offset places the cutters so that they engage the well bottom in an entirely different manner than when the cutters are offset in the old manner previously described. Thus, when the cutters are placed as shown in Fig. 1, relative to the bottom of the well, it will be seen that'as the drill is rotated in a righthand direction the cutters have only a slight lateral thrust against them, tending to cause them to rotate and the relative speed of rotation of the cutters will be greatly reduced. The progress around the bottom of the hole will be at the same speed as previously but the cutters will rotate upon their axes during the time it is traversing the well bottom at a very slow rate. Also, the teeth upon the cones will be presented against the formation so that the inner ends or sides of the teeth will engage the material rather than the sloping flanks of the teeth employed in the previous types of bits. The ends of the teeth will, therefore, have gouging action rather than the old chisel contact on bottom.

The improvement in this application includes the shaping of the teeth on such a drill in such manner that the forward advancing side of the tooth is adapted to plow into the formation, and thus more effectively disintegrate the material.

With reference to Fig. 2, it will be noted that the teeth 5 are formed with the advancing side thereof convex, so that it acts somewhat as the point of a plow moving the formation on bottom to either side and into the space around the tooth. In Fig. 2 it will be noted that there are spaces such as indicated at 8 around the teeth so that material may be moved away from the tooth into this space and thus be washed away by the flushing fluid. On the rearward or receding side of the tooth the face may be concaved, as shown at I, in Figs. 2 and 3.

Also, it will be apparent that the invention may be carried out by constructing the teeth angular in cross section as shown in Fig. 4. In this embodiment the plowing action on the bottom will be more pronounced. In the angular type of tooth the forward pointed face 8 is referred to as the convex side.

When a cutter having teeth of this formation thereon is moved about the bottom of the hole imthe manner shown in Fig. 1, the convex side of the teeth on the cutter are presented in a position toward the formation being cut. The cutter does not advance with its axis directed exactly forward and the cutter will, therefore. tend to rotate at a slow speed upon its axis as the cutter traverses the bottom of the hole.

With the tooth formed in this manner and with the cutter rotating it will be clear that the tooth not only has a plowing action but has a cutting action of the edges of the teeth as the cutter rotates. By the use of cutters with teeth thus formed an action on the bottom is obtained which is materially different from the action of chisel-shaped teeth of the approximately true rolling form of cone. Such prior teeth were adapted to roll in such manner that the chisel edge engages the bottom with a downward chisel stroke to form impressions, commonly called rock teeth, thereon. A more effective cutting action is obtained through my improved construction in which the rounded sides and crests contact the formation.

This type of cutter is intended for semi-hard and softer formations and in such formations it excells in cutting action the types of teeth normally employed upon bits of this character.

As will be obvious, this invention is particularly adapted for use on cutters mounted for operation with their cutter axes offset as described, but such teeth are not limited for use upon cutters so mounted and may be effectively employedon cutters mounted in the normal manner with the cutter axes approximately radial.

What is claimed is:

1. In a well drill having thereon a plurality of rolling cutters of approximately conical shape, the apices of said cutters being pointed forward side and spaced' apart on the cutter surface and formed with the convex side rounded transversely and presented forwardly in the direction of rotation so that it will engage and plow into the bottom of the hole.

3. In a rotary well drill having thereon a plurality of rolling cutters of approximately conical shape, the improvement comprising teeth on said cutters formed convex on the side toward the apex of the cutter and concave on the other side thereof, said sides being convex and concave from the base to the crest thereof in the direction extending transversely of said teeth.

4. In a rotary well drill having thereon a plurality of rolling cutters of approximately conical shape, the improvement comprising teeth on said cutters formed convex on one side and concave on the other side thereof, said sides being convex and concave from the base to the crest thereof in the direction extending transversely of said teeth, the cutters being so mounted as to present the'convex faces of said teeth forwardly in the direction of rotation of said drill.

5. In a rotary well drill having thereon a plurality of rolling cutters of approximately conical shape, said cutters being offset relatively to the axial center of the hole to point the smaller end of the cutter approximately forwardly in the direction of rotation, the improvement comprising teeth on said cutters formed convex on the side toward the smaller end of the cutter and concave on the other side thereof, said sides being convex and concave from the base to the crest thereof in the direction extending transversely of said teeth, the crests of said teeth being extensions of the convex side and rounded so as to plow into the formation.

FLOYD L. SCO'I'I.