US2334453A - Speed rock bit - Google Patents

Description

Nov. 16, 1943. P. J. SWOFFORD 2,334,453

SPEED ROCK BIT Filed April :50, 1942 Patented Nov. 16, 1943 UNITED STATES PATENT OFFICE I sPEEi iifzi BIT" Peter J. Swofl'ord, Fort Worth, Tex.

Application April 30, 1942, Serial No. 441,185

1 Claim.- ('Cl. 255-72) This invention relates to rock bits, and more particularly to a speed rock bit for cable tools, Y

and has for one of its objects the production of a simple and eflicient bit which is so constructed as to drill an annular or ring-like socket leaving a central core, which core may be broken-01f and removed intact after first removing the bit.

- A further object of this invention is the production of a simple and efficient hollow bit having a plurality of cutting teeth arranged in annular formation and having cutting faces tapering inwardly and laterally from the outer face and lower edge of the bit to provide a maximum cutting action.

Other objects and advantages of the present invention will appear throughout the following specification and claim.

In the drawing:

Figure 1 is a perspective view of the bit;

Figure 2 is a side elevational view, certain parts being shown in vertical section;

Figure 3 is a bottom plan view of the bit illustrating the cutting teeth at the bottom of the bit;

Figure 4 is an enlarged vertical sectional view taken on line 44 of Figure 3.

By referring to the drawing, it will be seen that Ill designates the body of the rock bit, which is provided with a tapering upper end l l having slotted vents l2 and the conventional upper end construction l3. The body Ill is provided with a central bore thereby defining a hollow body which hollow body is preferably about eight feet in length. The body I is provided with spaced longitudinally extending slots ll near the lower end of the body to provide a, series of annularly arranged teeth l5, preferably about two feet in length.

The lower cutting face of each tooth I5 is shaped to provide a centrally located outer cutting point I6, and the bottom edge of each tooth is inclined upwardly and rearwardly as indicated at H. The lower face of each tooth is also inclined rearwardly, upwardly and is also inclined laterally and inwardly from the center of the tooth toward the sides of the tooth as illustrated in detail in Figure 4 at l8.

In view of the fact that the teeth l5 are ar ranged annularly or in a ring-like formation, it should be understood that as the bit operates, an annular socket will be cut in the rock or hard formation through which the bit is operating for the length of the hollow body, thereby forming a core IS. The bit may then be withdrawn and a sand bucket having rippin dogs at the tom may be lowered to grip the core l9 and break about eight feet long.

off the core 19 close to its bottom as the bucket is lifted. The core l9 may then be brought out intact and this core will provide a log to demonstrate the type of formation through which the .bit has been operating.

By actual experiment it has been found that the present rock bit almost equals the speed of a rotary bit. It has been found that by drilling a 22 inch hole, the cutting surface in the present bit is 1 /2 inches, or three inches overall, leavin a core of approximately 19 inches in diameter in the center. As stated above, the body II! is provided with a plurality of spaced slots which run about two feet vertically of the body, from the bottom edge thereof, the body being preferably The core I: will be cut into the formation through which the bit is operating, and since the body is hollow, this core may extend for a considerable distance upwardly into the body, and when the maximum distance is reached, the bit may be withdrawn and a suitable sand bucket may be used as specified above for the purpose of removing the core intact. It has been found by actual practice that the use of this bit speeds up the conventional cable tool drilling approximately 75%.

The structure of the bit as illustrated and described also facilitates the sharpening of the bit and it has been found advantageous-to place a form in the slots I4 with the nub on the end and by striking the ends of the bit by means .of a blow from a sledge-hammer while the bit is hot, the bit may be reformed in the proper size and with the proper cutting surfaces; Where many sharpenings are necessary, a portable emerystone may be utilized having a proper angle to touch-up the cutting points of the bit.

It has been found by experience that in a rotary rig a well is often lost by passing up oil and going to salt water.

The present type of bit has been designed to fit the standard drill shaft and the teeth [5 are so constructed at theirlower ends so as to provide a diamond point near its lowest outer edge and these cutting faces taper inwardly or back toward the core, thereby providing all of the various cutting points necessary. It has been found that it is practically impossible for a bit of this type illustrated and described to ricochet or to cause a crooked hole, as often happens when using the standard tool.

It should be understood that certain detail changes in the construction of the device may be employed without departing from the spirit of the invention, so long as such changes fall within the scope of the appended claim.

Having described the invention, what is claimed is: a

A core bit of the class described comprising a cylindrical body having a central bore, a plurality of spaced slots extending longitudinally inward from one end of the body defining spaced cutting teeth, each tooth being bevelled on its working face from the middle to each adjacent 10 slot, each such bevel inclining away from the working race radially inward toward the bore and circumierentlally toward each adjacent slot whereby each tooth has a central radially extending cutting edge inclined toward the central bore away from the extremity of the tooth, and a plurality of other cutting edges at varying angles with respect to each other.

PETER J. SWOFFORD.

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