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Publication numberUS2262001 A
Publication typeGrant
Publication dateNov 11, 1941
Filing dateAug 21, 1939
Priority dateAug 21, 1939
Publication numberUS 2262001 A, US 2262001A, US-A-2262001, US2262001 A, US2262001A
InventorsMartin Hokanson
Original AssigneeEidco Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Drill bit
US 2262001 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

Nov. 1l, 1941. M. HoKANsoN DRILL BIT Filed Aug. 21, 1939 2 Sheets-Sheet l ATTRNEY.

Nov. l1, 1941A. M. HoKANsoN DRILL BIT 2 Sheets-Sheet 2 1N ENTOR, 6 ATT'ORNEY.

PatentedA Nov.` 11, 1941 Meran noknnson, Duluth.' Minn., assigner te Eidco, Incorporated, Duluth, Minn., a corporation of Minnesota'- nppueeuen August ai, 1939, serial No.- 291,168

This invention relates te drl special reference to improveme ts in that type of bit illustrated in my United States Patent No.

2,147,343, dated Feb. 14, 1939, and in my cOpeIld-V ing applications, Ser. Numbers 251,830; 264,791 and 284,939, and is indicative of that' type -of shown as being screw-threaded as by V-shaped improvements that can only be accomplished by.l l

continued and extensive experimentation in' actual practice with such a drill.

It has been found that in the larger types oi such a drill, increased speed and emciency are accomplished by the material modications and improvements shown, described` and claimed in' the instant case.

The duplication of the reaming action of an intermediate cutting portion of the bit is believed very material in the practical use ofmthe 'e bit in respect to both speed of cutting. and

This is particularly true l straightness of hole. e when it is realized that in a large bit of this type, the intermediate reamerI protrudes materially beyond the plane of the cutting edge of the cuter-y or major reamer, but, due to its relatively short length, requires no clearance taper whatever,

which reduces the gage loss to an absolute minimum, and also has the minimum tendency deviation from a straight hole,

A further advantage of duplication ofy the major reaming portion is that they diier only'fin. j

size and are subj ect to repeated sharpening from the inside of the depression by a likeshaped grinding or forming tool.

The principal object of the invention is, to divide up the ring formed between the outside reamer and the centralcutter by means of one or more sub-reamers. In this waythe width of these rings are cut in half or a third, etc.,

which makes the spalls less in size and more suitable for discharge out of the hole. f Other objects and advantages of the inven-f tion will appear in the following description Referring now to the accompanying `drawings, forming part of this application, and wherein like.

reference characters indicate like parts:

Figure 1 is a central vertical section, partly in volume. forgets-7a) bits and` has and 2 the various `cooperative parts of the bit are threading of the parts, it is thought obvious that in view of the various forms of such union as for example by square threads, or modiiied fric-y tion joints, which may be resorted to and are common in the art, further illustration or reference thereto is unnecessary, or that the parts may beformedintegral as shownl in Fig. 4, or 10,

any one of them separable as shown in Figure 5, without departing from the spirit of the invention.A v v y Inall. modifications I have, illustrated the bit as' beingprovidd with' a tapered yspigot `I for a suitable friction union to the operating mecha- `nism for imparting reciprocal motion thereto, and this may be either a drill rod or a cable operating means I'he spigot Itis shown as being formed integral with the cylindrical shank 2 of the bit, which, in this instance, tapers from the lower portion thereof in opposite directions, as at 3, to the upper smaller end of the headrportion 4. This Vhead portion is illustrated as comprising two opposed arcuate vrearning portionsS lying in the same circle with the diametrcally opposite portions of the head being attened as illustrated at 6 in p planes parallel with the axis and extending upwardly from the corners of the reaming edges to the point indicated at 1, which point is the junction of the inclined surface 3 with such plane surfaces. j j y l The attening of the sides in this manner is to provide ample clearance for the detritus or spalls, and obviously maybe enlarged or reduced as required in 'respect to the character of the material being drilled.' However the proportions here illustrated'are `deemed ideal in that such ample clearance is provided, and the strength of the bit head is in no wise impaired.

To further insure ample clearance for spalls it is to be noted that the lower edge of the head elevation, of a drill bit embodying the invention. y

Figure 2 is a similar view taken at right angles to Figure 1.

Figure 3 is a plan view of the cutting iace of the bit.

Figure 4 is a view similar to Figure 1 except that the various parts of the drill are shown integral, and the central cutter is ofthe reamer type.

Figure 5 is a view similar to Figure 4, except that it is at right angles thereto, and the central cutter is illustrated as being removable.'

Figure 6 is a view of the cutting face of the,60

bit shown in Figures 4 and 5. l e

While in the embodiment shown in Figures 1 4k intermediate of the opposed corners 8-8 in respect to each attened portion 6 is arched upwardly as at 9 and is cut away on an incline forming the bevel surface I0, and this cut-away portion may be varied materially in respect to the character of work being performed.

In respect to the angle of the walls of the depressionwhich form the reaming edges 5, they are illustrated as being of compound angular form, rst of all to give strength to the cutting edge and also for the purpose of lessening the amount of grinding necessary in sharpening the bit, which is always sharpened from the inside concavity by means. of suitable grinding wheels.

Within the hollow portion of the head I of the bit'illustrated in Figures 1 and 2 is installed the secondary 4or sub-reamer l I, it terminating downwardly in the opposed teaming edges I2 which in practically all respects is similar to the cutting edges 5 of the outer reamer. However the lower portion of this auxiliary reamer is preferably of cylindrical form except that it is cut-away similar to the outermost reamer, the diametrically opposite edges thereof forming the inclined arcuate surface I3, similar to the surface I in the outer reamer, to provide clearance for the spalls of the pilot portion of the bit. It will be noted that the sub-reamer is disposed with the cutting edges in alinement with the cutting edges of the outer reamer to insure freedom of the spalls so that no obstruction exists as the bit rotates during its reciprocal action, though, obviously, in some instances, it may be equally or more eiiicient to have the medial line through each cutting edge disposed at an angle to each other. The construction of this auxiliary reamer differs but slightly from that of the outer reamer in that although it is constantly forming a hole of shallow depth immediately in advance of the work of the outer reamer, the hole is so shallow that the auxiliary reamer does not need the tapered outer surface clearance angle which is required by the larger outer reamer. This construction of the auxiliary or sub-reamer is of great.v advantage because it may be ground many times with the absolute minimum loss of gage, and Provides added guidance to the drill in keeping it in perfect alinement.

'Ihe flattened sides |9- of the sub-reamer, as

well as those I8 of the central cutter portion, serve also for the purpose of convenience relative to the unscrewing of these parts from their respective sockets as by a wrench or the like.

While I have illustrated this type of bit as having a plurality of reamers one within another and an axially disposed pilot chisel, the reamers each having two opposed arcuate cutting edges, it is to be understood that the reamers may be constructed with three or more such arcuate cutting edges, as illustrated in my copending application, Serial Number 284,939, without departing from the spirit of the invention.

In Figures 4, and 6 are illustrated certain modications of the drill bit, such, for example, as in Figure 4, wherein all cutting portions of the bit are shown as being of integral construction and of reamer type, as, in using a reamer, subreamer, and a reamer type cutter, it is quitepossible that the actual wear of all parts would be quite similar, and, in such a case, it is quite practical to form them in one integral piece and sharpen the bit by means of ring grinders for the reamer portions and a cone or spherical grinder for the cutter portion.

In Figure 5 the leading cutting portion of the bit is illustrated at and is shown as being removable and attached to the head portion of the bit as by a suitable friction joint, common in the art. There are cases when it may be desirable to use a reamer, sub-reamer, which are integrally formed, with a cutter chisel of any ofseveral types, and thus it is illustrated as removable for such cases.

yHaving thus described my invention, what I claim and desire to secure by Letters Patent, is:

`l. A drill bit for percussion rock drilling comprising a body portion having an axial iiuid passageway therethrough for access of fluid to the working face of the bit body, said body terminating at one end in a cylindrical shank and means for application to the lower end of a drill rod, the body portion below said shank being hollow, enlarged and depressed at spaced intervals about the periphery of said enlargement,

an axial depression in said body portion forming the lower outer portions of said enlargement into a plurality of spaced arcuate reaming edges.

a secondary hollow reamer of smaller diameter within the hollow of said head and projecting axially from said enlargement having spaced depressions about its periphery, an axial depression within said secondary reamer terminatingy at its lower outer edges in a plurality of spaced arcuate cutting edges, anda central axially disposed cutter portion within and projecting axially from and of smaller diameter than said sub-reamer.

2. A drill bit of the type described having an axial fluid passageway therethrough, comprising an outer reaming portion having a plurality of spaced arcuate reaming edges formed by a depression therein, a secondary reaming portion within and projecting from the depression in said outer reamer portion, said secondary reaming portion having a depression therein and a plurality of spaced arcuate reaming edges, and a central cutter portion within and projecting from the depression in said secondary reaming portion.

3. A drill bit substantially as set forth in claim 2 wherein all of the cutting edges o! said reaming and central portions are so formed as to break the cuttings therefrom inwardly.

4. A drill bit substantially as set forth in claim 2 wherein the space lbetween each pair of arcuate cutting edges is upwardly arched and beveled to form additional cutting edges.

5. A drin bit of the type described for percussion rock drilling, comprising a substantially cylindrical shank portion, and an integral enlarged head, the lower outer portion of which terminates in a plurality of projecting arcuate reaming members and having a socket axially within said lower -head portion, la secondary smaller reaming member removably applied to said socket, the lower outer portion of which terminates in a plurality of circumferentially spaced arcuate reaming edges projecting beyond a plane with said first mentioned reaming edges, said secondary member also having a socket axially ofand extending inwardly from` the lower outer portion thereof, and a third cutting member removably applied to thev socket in said secondary member and extending beyond a .plane with the arcuate reaming edges thereof, said sockets and removable members each extending but a portion of the length ofthe members in which they are formed to insure as sturdy and durable a separable bit as possible.

6. A drill bit for percussion rock drilling comprising a head portion consisting of a plurality of substantially similarly shaped reamers, progressively graduated in size, each consisting of a substantially cylindrical body, flattened at spaced intervals about its sides and having an axial depression in the face and extending to the periphery thereof said depression having an axis coincident with the bit axis and forming the lower outer end into a plurality of spaced arcuate reaming cutting edges lying in the same circle, the largest of said reamers being removably attachable to the lower end of a string of drill rod and each of said smaller reamers extending from the depression in the next larger reamer.

7. A drill bit substantially as set forth in claim 6, characterized by the spaces intermediate of each adjacent pair of arcuate cutting edges beiig cut-away arcuately on an axis transverse the MARTIN HOKANSON.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2532783 *Sep 30, 1946Dec 5, 1950Orville PhippsSelf-piloted rotary drill bit
US2592440 *Jun 26, 1946Apr 8, 1952Thompson Products LtdRock drilling tool
US2648524 *Nov 21, 1947Aug 11, 1953Joseph DionisottiMining trepan
US2767958 *Sep 2, 1954Oct 23, 1956Paul W La BineRock drill bit
US2879037 *Jun 10, 1955Mar 24, 1959Wolfram Norman ERock drill bit
US4100979 *Dec 17, 1976Jul 18, 1978Paul SchmidtPneumatic percussion boring device
US4324300 *Jun 30, 1980Apr 13, 1982Logan Jr Clifford KRotary drill bit
US4386669 *Dec 8, 1980Jun 7, 1983Evans Robert FDrill bit with yielding support and force applying structure for abrasion cutting elements
US4574895 *Dec 29, 1983Mar 11, 1986Hughes Tool Company - UsaSolid head bit with tungsten carbide central core
US7673706Mar 30, 2006Mar 9, 2010Sandvik Intellectual Property AbDown-the-hole hammer with pilot and method of enlarging a hole
US20070227777 *Mar 30, 2006Oct 4, 2007Sandvik Intellectual Property AbDown-the-hole hammer with pilot and method of enlarging a hole
U.S. Classification175/390, 175/412, 175/417
International ClassificationE21B10/36, E21B10/40
Cooperative ClassificationE21B10/40
European ClassificationE21B10/40