US 3011571 A
Description (OCR text may contain errors)
Dec. 5, 1961 o. DE BREE ETAL 3,011,571
SELF CLEANING ROCK DRILL BIT Filed Jan. 23, 1961 INVENTOR5. OSCAR-L-DEBREE PAUL J' BOU DREZ ATTORNE Y United States Patent 3,011,571 SELF CLEANING ROCK DRILL BIT Oscar L. De Bree, 1200 Penufield Road, and Paul J. Boudrez, 334 Titus Ave., both of Rochester, N.Y. Filed Jan. 23, 1961, Ser. No. 84,167 2 Claims. (Cl. 175-413) This invention relates to a rock drill bit, and more particularly to a drill bit having provision for continuous self cleaning during the drilling operation.
Rock drill bits used in conjunction with pneumatic hammers have been proposed in which compressed air from the hollow drill rod is discharged through the bit face, in an effort to cause the rock chips to be driven upward along the drill rod. The presence of air ports in the face of the drill bit presents a problem in that such ports may readily become plugged with rock chips, despite the pressure of the air stream. The small diameter of the ports in the face of the bit, is such that once plugged, the air pressure supplied to the hollow drill rod is insuificient or ineffective to unplug the ports.
The present invention is directed to a drill bit, in which there is provided one or more ports, directed away from the cutting face of the bit. The invention is further directed to a drill bit of unitary construction, and in which air blast ports are directed away from the cutting operation so as to be protected from being plugged by the cuttings and force of the hammer action of the drill bit tending to force the cuttings into the ports.
A primary object of the invention is to provide a drill bit capable of drilling through a sequence of rock, stone, and earth overburden at a fast rate of speed without necessity for changing bits when passing from earth overburden to rock drilling, and in which the self cleaning action remains efiective at all times, by reason of the air blast being directed rearwardly of the cutting face where it is protected from being plugged by chips or earth which would be driven into the air discharge ports if located in the cutting face of the drill.
A further object of the invention is to provide a new and improved drill bit, in which air is forced down the hollow drill rod and through air passages in the bit and emitted out of the top of the bit, or rearwardly of the direction of the drilling operation. The air action, discharging rearwardly provides an air lift or suction below the discharge which draws the rock chips or earth into the blast, whence the drillings are blown up the annular passage formed by the drilled hole around the drill rod and discharged from the hole entrance.
A still further object of the invention is to provide a drill bit that will pulverize rock and which will continue to remain efiicient through long periods of use Without becoming clogged, or necessitating regrinding of the cutting facets.
The above and other objects of the invention will appear more fully hereinafter from the following detailed description when taken in conjunction with the accompanying drawings. It is expressly understood that the drawings are employed for purposes of illustration only and are not designed as a definition of the limits of the invention, reference being had for this purpose to the appended claims.
In the drawings, wherein like reference characters indicate like parts:
FIGURE 1 is a top or rear plan view of the drill bit, as viewed from the line 11 of FIGURE 2;
FIGURE 2 is a side elevation of the drill bit;
FIGURE 3 is an end view of the cutting face; and
FIGURE 4 is a longitudinal sectional view through the drill bit, taken on the line 44 of FIGURE 1.
Referring to the drawings there is shown a rock drill bit mounted on the end of a drill rod 22 that is driven by a pneumatic hammer. The drill rod is rotated in the direcice tion of the arrow A, during hammer operation, and is provided with a left hand thread 24, engaging with a corresponding thread 26 in the sleeve portion 28 of the bit. The bit is formed of drill steel, and transverse slots 30 and 32 are milled in the end to receive hardened elements 33 of such material as tungsten-carbide.
After milling the slots, air discharge passages 34 and 36 are drilled in the sleeve portion, and primary air passages 38 and 40 disposed radially inward thereof are drilled, and the intervening metal milled away as at 42, to provide interconnections between the passages 34 and 33, and 36 and 40 respectively. The bit head is preferably of steel, cast or machined, to form the general outline shown, and after completion of the machining operations including drilling and milling, the head is air or Water hardened, following which the cutting elements 33 are silver or copper brazed in their respective slots, the elements 33 overlying the milled slots 42 serving to form a closure for the interconnections between the ports 38 and 40, and 34 and 36 respectively.
The cutting facets 33 are provided with cutting edges 35, and the adjacent cutting facets, are provided with intervening relief channels 31, for the upward passage of the pulverized rock, rock chips and earth. It will be seen that a heavy blast of air being supplied to the hollow drill rod during the drilling operations, a blast of air is continuously emitted upward and rearwardly of the drilling operation from the ports 34 and 36. Such blast creates a suction in the channels 31, drawing the earth, cuttings and the like continuously from the bit face, and the cutting action taking place thereat, and once the drillings rise to the region above the blast of the ports 34 and 36, the drillings are driven up the annulus formed by the hole being drilled and the drill rod 22. The continuous removal of the drillings leaves the drill bit cutting face clear to act upon the uncut rock in the end of the bore, and ehminates wasted effort tending to grind up chips already cut loose, with the result that the bit remains sharp over long periods of time.
Employing air discharge ports which open to the rear of the cutting face eliminates the tendency which would otherwise eXist of driving, by the hammering action, chips and the like into the ports with a constant tendency of the plugging thereof. The drill bit, as described is essentially a one piece rigid and hardened sleeve with its grooves to receive the cutting elements, and by the fabrication of the sleeve in the manner described, the tortuous passage for the air blast is easily formed at low cost, with the closure of the interconnecting milled slots 42 being eiiected by the brazing or otherwise bonding in place of the cutting blocks 33. i
There is thus provided a solid rugged bit having long life and capable of rapid drilling operation through sequences of widely varying rock strata, without interruption due to plugging.
While a single form of the invention is shown, it is to be understood that the invention is not limited thereto. As various changes in the construction and arrangement may be made without departing from the spirit of the invention, as will be apparent to those skilled in the art, reference will be had to the appended claims for a definition of the limits of the invention.
What is claimed is:
l. A pneumatic drill bit comprising a one piece head and sleeve, said sleeve being internally threaded to receive a hollow drill rod, and said head having radial slots in its face to receive cutting elements, an air discharge port extending from a radial slot lengthwise through the sleeve and a primary air port extending from the same slot and extending through the head and located radially inward of said first named port and within the inside sleeve wall, a radial connecting passage formed in the base of the slot and connecting said discharge and primary ports, and a cutting element disposed in said slot and forming a closure for said connecting passage.
2. A pneumatic drill bit comprising a one piece head and sleeve, said sleeve being internally threaded to re ceive a hollow drill rod, and said head having four uniformly spaced radial slots in its face to receive cutting elements, air discharge ports extending from two of said opposed radial slots lengthwise through the sleeve and primary air ports extending from the same slots and extending through the head and located radially inward of said first named ports and within the inside sleeve wall, radial connecting passages formed in the base of the said two of the slots and connecting said respective discharge and primary ports, and cutting elements disposed in said slots and forming a closure for said connecting passages in said two of said slots.
References Cited in the file of this patent UNITED STATES PATENTS 2,022,194 Galvin Nov. 26, 1935 2,085,941 Arnold July 6, 1937 2,101,865 McCallum Dec. 14, 1937 2,485,098 Johnson Oct. 18, 1949 2,522,045 Knowles Sept. 12, 1950