US2527838A - Bit and cutter therefor - Google Patents

Description

Oct. 31, 1950 E. A. MORLAN EIAL 2,527,838

BIT AND CUTTER THEREFOR Filed Aug. 1, 1946 2 Sheets-Sheet 1 EAMORLAN. H.B.Wooos INVENTOR3 ATTORNEI Oct. 31, 1950 1;. A. MORLAN EI'AL BIT. AND CUTTER THEREFOR Filed Aug. 1, 1946 2 Sheets-Sheet 2 0 DS NVENTORS ATTORNEY.

Patented Oct. 31, 1950 UNITED STATES PATENT OFFICE.

BIT AND CUTTER THEREFOR Erwin A. Morlan and Henry B. Woods, Houston,

Tex., assignors to Hughes Tool Company, Houston, Tex., a corporation of Delaware Application August 1, 1946, Serial No. 687,768

The invention relates to a rotary drill having rotatable cutters thereon.

In the actual use of drill'bits of this type considerable difficulty is encountered in maintaining the gauge of the hole due to the fact that the gauge surface of the cutter is caused to perform a rubbing and crushing action on the wall of the well bore. If the gauge of the cutter is a smooth unbroken annular surface, there is no facility for easy removal of cuttings after they have been loosened from the wall of the hole. Such cuttings tend to wedge in the narrow space between the gauge of the cutter and the wall of the hole, forcing the cutter away from the wall and putting undue strain on the bearings.

It is common practice to interrupt the gauge surface with elemental notches so as to form spaced blocks, then rock cuttings may lodge in such notches between the blocks as they are removed from the wall of the hole and, when the cutter rotates and exposes these notches to the flushing fluid, the cuttings are washed away.

In most cases the elemental cutter teeth on the cutter adjacent the gauge surface tend to generate a gear on the bottom of the hole adjacent to the wall, and. if the notches on the gauge surface have the same spacing as the longitudinal teeth, they generate on the wall of the hole spaced grooves and ribs, or rifles, which reduce the effective diameter of the well bore. Excessive wear incident to the rifiing results because of the dragging action of each block as it engages the lands on the wall.

The foregoing is particularly true when using the cone type of rotary drill and the following description is directed to the embodiment of the invention in this type of drill. However, it is to be understood that such disclosure is by way of illustration only.

It is one of the objects of the present invention to provide the cutters of a rotary rock drill with heel surfaces which will generate a smooth wall on the well bore.-

Another object of the invention is to interrupt the circumferential gauge cutting web of a rotary type of drill at spaced intervals 50 as to form gauge cutting blocks or projections.

It is a further object of the present invention to provide a rotary type of cutter with a row of circumferentially spaced longitudinally disposed heel teeth which are joined at their outer ends with a circumferential gauge cutting web.

Another object of the invention is to provide a rotary drill cutter with a row of heel teeth and a notchedcircumferential web where th relative 6 Claims. (01. 255-71) position of the notches with respect to adjacent heel teeth varies about the cutter.

Still another object of the invention is to provide interruptions in the circumferential web of a rotatable type cutter which are non-uniformly and circumferentially spaced with respect to the circumferential spacing of the heel teeth.

It is also an object to provide an efficient gauge cutting surface for roller type drills.

Othenand further objects of the invention will be readily apparent when the following description is considered in connection with the accompanying drawings wherein:

Fig. l is a perspective view of a drill bit having cones to which the invention has been applied;

Fig. 2 is a plan view looking at the base of a cone with the gauge surface interrupted by notches spaced apart a little less than alternate heel teeth;

Fig. 3 is a plan view looking at the base of a cone where the gauge surface is interrupted by uniformly spaced notches in excess of half the number of teeth;

Fig. 4 is a plan view looking at the base of a cone where the circumferential web has been in- V terrupted and the number of interruptions is less than half of the number of heel teeth;

Fig. 5 is a plan view looking at the base of a cone where the number of notches in the circumferential web exceeds the number of heel teeth. f p v In Fig. 1 the drill bit 2 embodying the invention is made up of a body 3 having the threaded pin 4 thereon by which it is connected to the drill collar or drill stem. The body has the downwardly projecting legs 5 each of which carries a cone type cutter 1. There are three such cutters, &, 9 and it, which are circumferentially spaced in such a manner that upon rotation of the cones on the bottom of the hole the formation will be out.

It is important that a drill bit of this type be so constructed as to avoid the formation of rock teeth upon the bottom ll of the well bore and also to maintain the desired gage of the bore 12 with a minimum of wear upon the cutters l or the bearings therefor. To this end each of the cones or cutters l is provided with a row 2| of heel teeth 22 angularly spaced therearound. A circumferential web 36 upon the ends of the heel teeth of atleast some of the cutters spans the space 23 between successive teeth and serves to produce a cutting action at the point 16 where the bottom merges with the side wall l5 of the bore. Such action assists the teeth '22 in ef- If the gage surface I8 is continuous, disintegrated particles of rock or other earth material may enter between such surface and the side wall of the bore whereby excessive wear is produced upon the drill bit without commensurate action tending to maintain the desired gage. Also, the removal of disintegrated particles of rock from the well is impeded by this condition.

An important feature of the invention resides in the elimination of the condition to which reference has just been made. To this end the web is provided with a plurality of notches 32 whereby there are created a plurality of spaced blocks or projections 33 having edges 34 which, together with the block surface l8, assist in maintaining the desired gage of the bore I2.

The spaces or notches 32 are adapted to receive rock cuttings whereby such cuttings are subjected to the action of the flushing fluid and are removed from proximity to the cutters I.

In Fig. 1 each of the cones 1 ha been illustrated as having such an angular span of each block 33 and the adjacent notch 32 that a block or projection 35 of lesser width than the remaining blocks 33 is provided. It thus seems apparent that there are varying relations between the heel teeth 22 and the blocks 33 and 35. By virtue of such varying relation the notch adjacent a given tooth does not bear the samerelation to that tooth as the next notch bears to its adjacent tooth. By means of this arrangement tracking is avoided because the blocks or projections are continuously engaging a surface at a different circumferentiall spaced position whereby a smooth wall is cut in forming the bore.

It will be noted, for instance, in the No. 8 cone in Fig. 1, that the notches cause the formation of web extensions 52 which project circumferentially beyond the crest 43 of the next adjacent tooth. In some instances the edge 44 of the block or projection occurs at the crest 22 of a tooth whereas in other instances neither edge of the block or projection will coincide with a tooth crest. In this manner the severing of the rock teeth from the wall is assured and this web serves to cut the connection between the rock teeth and the wall of the bore without tracking of the web due to these unequal length extensions.

Fig. 1 shows the notches 32 as extending a substantial distance through the web 38 but not completely severing the web.

It seems obvious that various modifications of the arrangement and relative number of teeth and notches in the web can be devised. As a matter of fact almost innumerable combinations could be constructed. A few such combinations will be illustrated herewith as applied to cone type bits but it is intended that other type roller cutters, such as cross roller and roller core bits, may be similarly constructed.

Fig. 2 shows a base of the cone where twentythree heel teeth have been provided in the row and where there are twelve and one half blocks formed by thirteen notches where the small or half block 35 is formed by positioning the successive notches 32 and 31 relatively close together. This arrangement breaks up any tend ency for the lugs or blocks to track on the side of the well bore and also tends to prevent tracking of the cone on bottom because all of the rock teeth are cut loose by web extensions from the wall of the well bore due to this relative arrangement of the number of teeth and the number of notches or webs.

Fig. 3 shows an arrangement where there are twenty-three teeth and thirteen blocks all of uniform width and divided by the spaced notches 32. This arrangement gives variable length extensions 42 with respect to the crests 22 of the teeth so as to prevent tracking. Fig. 4 shows the notches 32 as projecting entirely through the web 31! down to the point 50 which is approximately the elevation of the bottom of the trough between two adjacent teeth. This form provides variable extensions 42 of the blocks relative to the crests of the heel teeth. The number of heel teeth and the number of webs in Fig. 4 are the same as in Fig. 3, viz, twenty-three teeth and thirteen webs.

Fig. 5 shows still another modification where thenumber of webs exceeds the number of teeth and twenty-three teeth and twenty-five webs have been provided. This again avoids tracking not only on the wall but on the bottom of the bore as well. With this arrangement of Fig. 5 there is a tendency for less binding of the bit in the well bore because the size of the chips will be smaller and there are more undercuts for the chips to escape as they are formed.

Broadly the invention contemplates a cutter construction for rotary rock drills which will prevent tracking on the bottom and wall of the bore by the provision of cooperating web and heel tooth construction.

What is claimed is:

l. A rotary cone type drill comprising a body, a plurality of cones rotatable thereon, cutter teeth longitudinally of said cones including a row of heel teeth, a circular web integral with the outer ends of the heel teeth on at least one of the cones to cut the gage, said web having a plurality of web projections extending outwardly from the ends of the heel teeth and formed by notches in the outer face of the circular web, the number of notches being different from the number of heel teeth so that the web projections beyond the tooth crests are of different l ths.

2. A drill bit of the rotary cone type comprising a body, a plurality of cones rotatably mounted thereon, gage-cutting teeth on each cone, a circular web integral with the outer ends of the heel teeth on at least one of the cones, and a plurality of circular web extensions formed by substantially radial notches on the outer surface of said web, the number of said extensions approximating half the number of teeth.

3. A rotary drill bit of the cone type comprising a body, a plurality of cones rotatably mounted thereon, cutter teeth on said cone including a row of heel teeth, a. web integral with the outer ends of the heel teeth of at least one of the cones to cut the bit gage and joining the adjacent teeth to present a circular cutting web, said web being interrupted on its surface opposite the heel teeth to provide web extensions projecting axially and arranged annularly about the base of the cone, said interruptions being spaced to provide different length extensions to avoid tracking.

4. A rotary drill cutter comprising a body having a generally arcuate surface, a plurality of circumferentially spaced longitudinally disposed heelteeth, a circumferential web joining the outer ends of such teeth, and Web projec- 5 tions extending outwardly from the ends of the heel teeth and formed by radial notches circumferentially spaced in the outer surfaceof said Web. I

5. A rotary drill cutter comprising a generally conical surface, a plurality of circumferentially spaced longitudinally disposed heel teeth, a circumferential web joining the outer ends of such. teeth, and web projections extending outwardly from the ends of the heel teeth and formed by substantially radial notches circumferentially spaced in the outer surface of said web, on the gage surface of said conical surface.

6. A rotary drill cutter comprising a generally conical surface, a plurality of circumferentially spaced longitudinally disposed heel teeth, a circumferential web joining the outer ends of such teeth, and web projections extending outwardly from the ends of the heel teeth and formed by substantially radial notches circumferentially spaced in the outer surface of said web, where the number of teeth and number of notches are difierent so as to provide web extensions circumferentially of the teeth which are of varying lengths.

ERWIN A. MORLAN.

HENRY B. WOODS.

REFERENCES CITED UNITED STATES PATENTS Name Date Scott Nov. 21, 1944 Number

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