US2890021A - Drill bit - Google Patents

Description

June 9, 1959 s NDV 2,890,021

DRILL BIT Filed Oct. 29, 1956 20.55274. sax owe 24 IN V EN TOR.

United States Patent D LL BIT Rp rt L- Sfl d g Wh ie Calif a g o t Thor Power Tool Company, Aurora, 111., a corporation of Delaware i i Am i fipn O tobe 2 56 Serial No- $51 48 4 Claims. (Cl. 255-64) The present invention relates to drill bits in general and particularly to drill bits especially designed for percussive dr l n i r relatively high-speed penetration of solid material such as rock and concrete is today possible by the use of drills using a rota y drilling action and percussive drilling action or a combination of both. In each type of drilling the actual cutting of the material is accomplished by a drill the working end of which is called a drill bit and which usually includes one or more relatively hard abrasionresisting cutting elements which grind and chip the material to be removed. As the material is chipped cut away it must be removed from the hole being drilled, and the speed of drilling and the success of the operation are dependent upon the successful removal of the displaced material to prevent its becoming impacted in the end of the hole. Use has been made of fluid, both air and water, flowing down through the drill rod or steel to the cutting end and then back around the drill in the hole carrying the material with it. Fluid so directed, however, loses velocity as it reaches the Working face so that the scouring and cleaning action is minimized. Adlifionally, the size of the return passage in the hole around the drill is much greater than that of the fluidfeeding passage through the drill, resulting in a relatively sluggish flow of fluid from the hole which produces slow and sometimes ineffective chip displacement.

' The drill bit constructed in accordance with the present invention is particularly designed for a drilling operation in which the cleaning fluid is drawn by suction down and into the hole being bored and then into the working end of the drill bit to be concentrated at a few small ports at the working face. This gives to the cleaning fluid a high-speed scouring action at the face itself, the; arrangement of the face of the drill bit and the sides thereof being so designed that this scouring action is increased to a maximum. The foreign material entrained in the fluid. stream is displaced longitudinally through the drill steel from the bit and carried to the exterior where it can be separated from the fluid by any suitable means or exhausted to the ambient if that be permissible.

With an appreciation of the problems present in the field to which they present invention relates, it is an objeet to'provide a new and improved drill or drill bit inwhich the chip-clearing and scouring action of the cleaning fluid is of maximum effectiveness with the drill connected to a source of suction.

Another object of the invention is to provide a new and improved drill bit in which air can be drawn by suction through the bit and around the drilling face at maximum velocity for maximum chip cleaning effectiveness.

Another object of the invention is to provide a new andimproved drill bit particularly adapted for percussive drilling with suction in which the drill bit body i so constructed and designed as to accomplish maximum chip removal by the available suction.

these other more specific objects, will appear upon reading the following specification and claims, and upon Patented June 9, 1959 considering in connection therewith the attached drawing to rvhich they relate.

Referring .again to the drawing in which a preferred embodiment .of the invention is disclosed:

Figure 1 illustrates a drill bit constructed in accordance with the present invention positioned at the end of a drill steel and in a hole being drilled;

Figure 2 is a longitudinal section through the construction as shown in Figure 1 also being a section upon the line 22 of Figure 3 Figure 3. is an end view looking in the directions of the arrows upon the line 3-3 .of Figure 2; and

Figure 4 is a longitudinal section upon the line 4-4 of Figure 3..

Referring again to the drawing, the drill bit construction in accordance with the present invention is indicated generally by the reference character 10 and is seen to be attached at the outer end of a drill steel 11 and positioned within a hole H in rock or concrete, for example, in which it is drilling. The drill steel 11 may be connected to. any suitable power-actuated drill, either of the rotary or percussive reciprocating type and preferably the latter. Drill steel 11 is provided with a longitudinally-extending bore or passage 12 and at its outer or lower end is tapered at. 1.3. to enable it to. make a friction-locking fit with the drill bit 10. The length of the steel 11 may vary. In the conventional use of such units they are connected insectiens, intermediate sections being coupled to one another by suitable means which seal them together. The operat-ion of Such drills and the interconnection of such drill steels are disclosed in applicants co-pending applications Serial No. 636,311 and Serial No. 618,749 (now abandoned), respectively.

Drill bit 10. compnses a body 15 formed of metal which is exteriorly conical for its entire length at surface 14 which is provided with flats 16 in chordal planes parallel to, the longitudinal axis. As is seen most clearly in Figure 3, the. lower Working end or face of the drills is multisiderl with spaced arcs lying on the surface of the cone comprising the principal shape of the bit body separated bgthe, flats 16..

Drill body 15 is provided interiorly at one end with a conical seat 19 sized to receive and seat the tapered end 13 of the drill steel 11. The relationship is such that when Seated the end ofthe steel is spaced from the bottom of the. seat leaving a chamber 21 which opens directly into the longitudinal bore. 12 extended through the steel.

Portsor passages 22 extend between the chamber 21 and the working face 17 of the drill body, the outer ends of the ports in the Working face being in substantial tangently to the. fiat 16 in each instance. This relationship is shown most clearly in Figures 2 and 3.

The Working face 17 is provided with transverselyextending diametric grooves or slots 24 adapted to re ceive and seat cutting elements. These elements are indicated by the reference characters 26 and 27, 26 being seen to extend the. entire width of the cutting face while elements: are positioned upon its opposite sides. Each of; the. elements is provided with a cutting edge which extends the greatest distance. from the plane of working face 1 7, all of the cutting edges lying in substantially the. same, plane. The retention of the cutting elements in their seats 24 may be accomplished in any suitable manner as. by brazing, welding, etc. These elements in a preferred form are made of tungsten carbide or othersuitable abrasion-resisting material.

In the Operation of a tool constructed in accordance with the invention the. drill steel and bit are connected tea drill and operated in the manner disclosed in applicants s -s nding application Serial No. 636,311. Thedrill stee], is, reciprocated at high frequency and with it the drill bit 10. Suction at the drill proper is made available at the port 22 in the drill bit through the chem-- ber 21 which connects through the longitudinal bore 12 to the suction source. I

The high-speed reciprocation of the drill bit in the hole H causes the cutting elements 26'and 27 to chip the rock or concrete and the presence'of suction causes the air to be drawn down the hole H and around the drill steel and the drill bit. The bit 10 at 'its working face is of maximum diameter and its conical surface 14 at that face closely approaches the Wall of the enclosing hole H. The flats 16, however, provide arcuately spaced channels through which the larger part of the air travels.

The suction is available directly at the ends of the ports 22 and the air rushing through the channels provided by flats 16 sharply reverses its direction as it rounds the face of the bit to provide a scouring action which removes foreign material from the bottom of the hole and conveys it to the ports 22 from which it makes its way through the chamber 21 into the bore 22 to be exhausted at the drill proper into a suitable dirt separator or into the ambient atmosphere. The entrained air in the passages 22, chamber 21 and bore 12 travels to the source of suction at a velocity which is much higher than would be the case if it were traveling in the hole around the drill. As a result, the chips and foreign material are effectively exhausted. The pick-up action at the working face is also improved. The channels formed by the flats 16 with the cooperation of the wall of the encircling hole H direct the air to pockets formed by the included angle between cutting elements 26 and 27 in cooperation with the working face 17 and the adjacent end of the hole H. A port 22 opens into each of these pockets right at the end of the flat 16, as described. The result is that the flow of air into each port is largely air from the adjacent channel with resulting increased concentration of air flow velocities at the lower ends of the flats 16.

While the particular device herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as defined in the appended claims.

I claim:

1. A percussion rock bit adapted to be operated with suction applied to the central bore thereof comprising a solid metal body exteriorly conical except for circumferentially spaced flats which lie in planes parallel to the axis of said body and which provide air channels with said body positioned within a hole being drilled, transversely-extended cutting elements in the cutting face of said body the cutting edges of which extend radially between the lateral edges of adjacent one of said flats, said body being formed interiorly with an axial drill steel seat spaced from said cutting face and communicating with passages which diverge outwardly from said seat and opening at their outer ends through flat surfaces substantially normal to the bit axis and between cutting elements, and means whereby suction may be applied interiorly of said drill body at said seat with said body positioned within a closely surrounding hole being drilled so that air will be drawn exteriorly along said body largely through said air channels formed by said flats with the adjacent walls of the surrounding hole to ends of said passages and will reverse its direction of travel to enter said passages and in doing so perform a scouring action which picks up and removes cuttings from the end of the hole being drifled adjacent said cutting faces.

2. A percussion rock bit adapted to be operated with suction applied to the central bore thereof comprising a solid metal body having a flat end normal to the bit axis and exteriorly conical except for circumferentially spaced flats which lie in planes parallel to the axis of said body and which provide air channels with said body positioned Within a hole being drilled, transverselyextended cutting elements in said fiat cutting end of said body the cutting edges of which'extend radially between said flats, said body being formed interiorly with a drill steel socket having ports which diverge from the bottom of said socket toward said flat cutting end and terminate therein in each instance in substantial tangency to one of said flats and between cutting elements, whereby upon suction being applied interiorly of said drill body at said seat with said body positioned within a closely surrounding hole being drilled the suction in said body will be made available at a point immediately adjacent the ends of said air channels to obtain maximum velocity of air flow at said ends and maximum scouring and grindingsdisplacement action.

3. A percussion rock bit adapted to be operated with suction applied to the central bore thereof comprising a solid metal body having a flat end and exteriorly conical except for circumferentially spaced flats which lie in planes parallel to the major axis of said body and which provide air channels with said body positioned within a hole being drilled, radially extending cutting element seats in the cutting face of said body, cutting elements secured in seats each formed with a cutting edge lying in a plane forward of said flat cutting end, said flats being positioned in each instance in the angle between adjacent cutting elements, said body being formed interiorly with a drill steel seat open to its end spaced from said cutting face and with passages which diverge outwardly from said seat with their opposite ends terminating in said flat cutting end in immediate adjacency to a flat, whereby upon contact of said cutting element with the end of a hole being drilled each passage and adjacent channel opens into a separate pocket formed by the cutting face and the cutting elements with the adjacent end of the hole being drilled to insure maximum effectiveness of the suction available in each passage to draw air directly from the adjacent channel.

4. A percussive type rock bit adapted to be operated with suction applied to internal passage means extending longitudinally thereof to remove cuttings, said bit having a generally circular body having a substantially flat end lying normal to the bit axis, a plurality of cutting elements mounted radially of said flat end, said body being generally conical in shape with its larger diameter portion adjacent said flat end, said body also having flats along the side thereof opening through said flat end at points between the adjacent ends of said cutting elements, said body having an axial socket seating the end of a hollow drill steel shank, and suction air passages extending between the inner end of said socket and the fiat end of said body at points closely spaced to the merger of said flats with the flat end of said bit, where by suction pressure applied to said socket and to said passages is effective to draw air past said flats and into the outer ends of said passages at high velocity at points closely spaced from the bottom of the bore being drilled, and whereby the flat end of said bit cooperates with said cutting elements in disintegrating cuttings to a size readily removed by suction air flow.

References Cited in the file of this patent UNITED STATES PATENTS 2,103,359 Graham Dec. 28, 1937 2,124,609 Dickenson July 26, 1938 2,602,641 Wade July 8, 1952 2,733,943 Nater Feb. 7, 1956 FOREIGN PATENTS 136,988 Australia Apr. 18, 1950 919,402 Germany Oct. 21, 1954

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