US3035647A - Rotary drill bit - Google Patents

Description

May 22, 1962 A. F. PICKARD ETAL ROTARY DRILL BIT Filed Feb. 27, 1959 Kar/ c/. H/apka United States Patent 3,035,647 ROTARY DRILL BIT Albert F. Pickard, Karl J. Klapka, and Leo Catallo, Detroit, Mich., assignors to Wheel Trueing Tool Company, Detroit, Mich., a corporation of Delaware Filed Feb. 27, 1959, Ser. No. 796,124 6 Claims. (Cl. 175-387) This invention relates to rotary drill bits and more particularly relates to a rotary drill bit adapted to cut large diameter shallow holes or recesses, in rock, concrete, or the like.

It is often desirable to cut shallow but relatively large diameter holes in very hard surfaces such as concrete and the like for such purposes as cutting light-receiving sockets for landing lights in a concrete airplane runway. It has in the past, however, been found ditficult to prevent large diameter drill bits from slipping along the surface to be cut as the cutting operation is being initiated.

In order to obviate the difficulties involved in cutting large diameter holes in concrete or the like with ordinary drill bits, we have devised a drill bit which has a relatively small diameter abrasive annulus formed centrally of a substantially flat abrading face and protruding from the abrading face. This abrasive annulus initially contacts and cuts into the surface to be drilled to thereby cut a small groove in that surface prior to contact of the large diameter fiat abrading face therewith.

The abrasive member has a plurality of particle collection areas or countersinks formed therein which are communicable through suitable channels with the periphery of the drill bit and which are adapted to be supplied with pressurized fluid from a central bore formed within the drill bit to wash fine particles and sludge from the bit.

The abrasive member is removably connected with a mounting member by a plurality of bolts or other suitable securing means which are disposed within the respective eountersinks in the abrasive member so as to be readily accessible to permit removal of the abrasive member from the mounting member as desired.

The rotary drill bit which is illustrated in the drawings also has an annular abrading ring formed about the periphery of the drill bit which is adapted to form a water collection trap in the material being drilled about the periphery of the drilled hole but the central abrading ring protrudes from the substantially flat surface of the abrading face a distance greater than the peripheral abrading ringso that the central abrading ring bites the surface of the material to be drilled prior to contact of the outer abrading ring therewith. In this manner, slippage of the drill bit over the material to be drilled is prevented and the drill bit is readily steadied in its proper position during the operation thereof.

A central bore is formed in the abrasive member which is communicable with a source of pressurized fluid and which is also communicable with each of the several countersinks to provide a means for properly cooling the abrading head of the drill bit and to also provide a means for flushing the drilled particles from the path of movement of the abrading face of the drill bit. While the provision of such a bore in the drill bit leaves an upstanding core in the drilled hole, the core is relatively short and of small diameter and may be readily chipped away after the drilling operation.

It is important to note that the bore formed within the mounting member is diametrically smaller than the coaxially aligned bore formed within the abrasive member so that a shoulder is formed on the mounting member intermediate the radially enlarged and radially reduced bores which is adapted to abut the central core remaining in the drilled hole. Upon contact of the core with this shoulder, the drill bit is prevented from moving deeper ice into the material to be drilled so that holes of constant depth may readily be drilled. Obviously, the depth of the hole to be drilled will be determined by the distance intermediate the shoulder defining the radially reduced bore within the mounting member and the abrading face of the abrasive member.

Accordingly, it is a principal object of the present invention to provide a rotary drill bit which is not subject to slippage or travel over the surface to be drilled upon the initiation of the drilling operation.

Another object of the invention is to provide a two-part drill bit comprising a mounting and an abrasive member in which ready access may be had to the securing means interconnecting the members with one another.

A further object of the invention is to provide a drill bit of the type above described having a means for adequately cooling the abrasive surface of the bit and for flushing foreign particles from the bit.

Yet another object of the present invention is to provide a drill bit which is not subject to slippage upon initiation of the drilling operation which has a simple and eflicient means for drilling holes of constant depth.

These and other objects of the invention will become apparent from time to time as the following specification proceeds and with reference to the accompanying drawings, wherein:

FIGURE 1 is a plan view of the abrading face of a drill bit constructed in accordance with the principles of the present invention; and

FIGURE 2 is a vertical sectional view through the bit illustrated in FIGURE 1 which is taken along lines II-II of FIGURE 1.

As shown in the drawings, a drill bit 10 comprises generally a mounting member 11 and an abrasive member 12 which are connected together by means of a plurality of cooperating nuts and bolts 13 which extend through coaxially aligned apertures 14 in the respective members.

The mounting member 11 has a bore 15 formed centrally therein which is threaded as at 16 to be secured to the barrel of a drilling machine. The abrasive member 12 has a bore 17 formed, centrally therein disposed in registry with the bore 15 and has an annular flange 18 formed integrally therewith and extending upwardly therefrom which is adapted to seat within a central recess 19 in the mounting member 11.

An abrasive face 20 having a plurality of diamonds or other suitable abrasives secured therein is provided on the lower surface of the abrasive member 12 following the contours thereof and extending upwardly along the outer edge thereof and into the bore 17 as an integral part of said member 12.

An annulus or bead 21 is formed about the outer periphery of the abrasive member 12 and is arranged to form a groove 21a in the concrete 22 during the drilling operation to provide a well for containing any fluid seeping into the hole 22a drilled by the bit 10 about the periphery thereof.

A second annular ring or head 23 is formed radially inwardly of the ring 21 coaxially with the bore 17 and extends axially downwardly of the substantially fiat abrading face 20 of the abrading member 12 a greater distance than the annular ring 21 so that when the drilling operation is begun the annular ring 23 will contact and cut the concrete prior to the contact of the annular ring 21 therewith.

It is to be noted that the ring 23 has a diameter less than half that of the face 20 and that due to the relatively small contact area of the ring 23 with the concrete the bit may readily be steadied and prevented from slipping by the operator thereof and the annular ring 23 will act as a guide or pilot to initially cut into the surface of the concrete prior to movement of the entire abrading surface into contact therewith.

As shown in the drawings, the annular bead 23 tapers downwardly at the sides to present downwardly convergent side cutting surfaces. The cross section of the bead in the preferred illustrated form is rounded or arcuate. The bead will first engage the surface of the concrete in line contact. As soon as the bead starts cutting, the line contact will broaden as the surfaces on each side of the bead cut down into the concrete. The bead will cut a rounded depression in the concrete, with the curved sides of the depression facing upwardly and laterally toward the bead preventing lateral displacement. The bead is thus at all times during the cutting action always cutting fresh concrete with its lateral surfaces thus insuring the absence of lateral shifting.

As shown most clearly in FIGURE 1, a plurality of wells or countersinks 25 are formed within the substantially flat face 20 of the bit 10. The face 20 is also cut out as at 26 to provide a means for communicating pressurized fluid from the coaxially aligned bores and 17 to the respective wells 25. Assuming that the bit 10 is arranged for counterclockwise rotatable movement as viewed in FIGURE 1, a plurality of passages 27 are formed through the abrasive face 20 by cutting out portions of the face 20 which extend in a clockwise direction from each of the wells and which terminate at the periphery of the abrasive member 12.

The face 20 is also cut out as at 28 through the annular ring 21 to permit fluid flow from the wells 25 to the periphery of the abrasive member 12.

Fluid pumped at high pressure through the coaxially aligned bores 15 and 17, in the manner which is Well known in the art, will flow through the passages 26 into the Wells 25 where it will collect the relatively fine particles cut in the concrete by the bit 10 and will flush the same out through the passages 27 and 28 to the periphery of the bit 10.

Applicants have thus provided a drill bit for drilling large diameter shallow holes in hard surfaces such as concrete or the like which may readily be prevented from slipping over the surface to be drilled during the drilling operation and which may readily be guided by the operator thereof. In addition the invention is directed to a means for cooling and flushing the abrading surfaces of the drill bit.

It will be understood that this embodiment of the pres ent invention has been used for illustrative purposes only and that other features, modifications, and variations in the present invention may be effected without departing from the spirit and scope of the novel concepts thereof.

Weclaim as our invention:

1. A rotary drill bit having a substantially flat abrading face, an annular abrading ring formed about the periphery of said bit and protruding from said abrading face, and a second abrading ring protruding from said abrading face a greater distance than said first mentioned abrading ring and centrally thereof having a diameter less than onehalf that of said abrading face.

2. A rotary drill bit having a substantially flat abrading face, an annular ring formed about the periphery of said bit and protruding from said abrading face, a plurality of countersinks formed in said abrading face and opening to the periphery thereof through said annular ring, and a second abrading ring protruding from said abrading face a greater distance than said first mentioned abrading ring and centrally of said abrading face having a diameter less than one-half that of said abrading face.

3. A rotary drill bit having a substantially fiat abrading face, an annular ring formed about the periphery of said bit and protruding from said abrading face, a plurality of countersinks formed in said abrading face and opening to the periphery thereof through said abrading ring, radially inwardly disposed fluid flow passages opening to each of said countersinks, and a second abrading ring protruding from said abrading face centrally thereof a greater distance than said first mentioned abrading ring having a diameter less than one-half that of said abrading face.

4. A rotary drill bit having a substantially flat abrading face, a plurality of countersinks formed in said abrading face, a bore formed centrally within said bit and opening to said countersinks, passageway means leading from said countersinks to the periphery of said abrading face along a chord line of said abrading face so arranged that fluid disposed Within said countersinks will be directed therethrough during rotation of said bit, and an abrading ring protruding from said abrading face centrally thereof having a diameter less than one-half that of said abrading face.

5. A rotary drill bit comprising a mounting member and an abrading member mounted on said mounting member, a substantially flat abrading face formed in said abrading member, an annular ring formed about the periphery of said abrading member, bores formed centrally within each of said members and disposed in registry with one another, a plurality of countersinks formed in said abrading face, means communicating said bore within said abrading member with each of said countersinks, passageway means leading from said countersinks to the periphery of said abrading member so arranged that fluid disposed within said countersinks will be directed therethrough during rotation of said bit, securing means disposed within said countersinks and extending through each of said members for securing said members to one another, and an abrading ring protruding from said abrading face centrally thereof a greater distance than said annular ring and having a diameter less than one-half that of said abrading face.

6. A rotary drill bit comprising a mounting member and an abrading member mounted on said mounting member, a substantially flat abrading face formed in said abrading member, an annular ring formed about the periphery of said abrading member, bores formed centrally within each of said members and disposed in registry with one another, a plurality of countersinks formed in said abrading face, passageway means leading from said countersinks to the periphery of said abrading member along a chord line of said abrading member so arranged that fluid disposed within said countersinks will be directed therethrough during rotation of said bit, securing means disposed within said countersinks and extending through each of said members for securing said members to one another, and an abrading ring protruding from said abrading face centrally thereof a greater distance than said annular ring and having a diameter less than one-half that of said abrading face, the bore within said abrading member being diametrically greater than the bore within said mounting member.

References Cited in the file of this patent UNITED STATES PATENTS 137,435 Gillespie Apr. 1, 1873 1,088,452 Rist et al. Feb. 24, 1914 1,413,471 Goerner Apr. 18, 1922 1,805,678 Smith May 19, 1931 2,053,801 Mitchell Sept. 8, 1936 2,371,488 Williams Mar. 13, 1945 2,545,195 Crake Mar. 13, 1951 2,729,427 Davis et al Jan. 3, 1956 2,819,043 Henderson Jan. 7. 1958

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