US973407A - Rock-drilling bit. - Google Patents

Description

T. CONNELL. ROGK DRILLING BIT.

, APPLICATION FILED JULY 21, 1909.

Patented Oct. 18, 1910.

s'r s PA. E OFFICE.

TEBRENCE GONNELL, OF HAVERFORD, PENNSYLVANIA.-

ROCK-DRILLING BIT. 7

Specification of Letters Patent.

Patented Oct. is, 1910.

Application filed July 21, 1909. Serial No. 508,811.

more particular reference to a bit of that general type in which a number of radially disposed end cutting teeth are provided.

The object of the invention is to provide a bit of the above type in which the work is performed with a minimum expenditure of power and a minimum degree of resistance to the action of the cutting teeth. This object is accomplished by providing .a bit of such construction that a partial cutting and a partial grinding effect is produced in a novel manner, the grinding or crushing -action being an incident of the ordinary feeding and turning moments of the bit. Cone sequently, in the present construction a result i's incidentally accomplished which in the ordinary constructions is objectively ac complished: It follows from the foregoing statement that the actual cutting area may be considerably reduced andtherewith is had a reduction of the resistance encountered by driving the bit into the rock, the

crushing or grinding action being, as stated,

incidental, and'ofl'ering very little and a far less degree of resistance to the bit than would be the case if the area to which the crushing action is confined, were cut,\ as in spective view of a rock drilling bit con;

structed in accordance with the present invention. Fig; 2 is an end elevation thereof. Fig. 3 is a longitudinal sectional view thereof on the-line 33 of Fig. 2 and Fig.4 is a similar view thereof on the line 4-4 of Fig. 2. imilar characters of reference designate corresponding parts throughout the several views.

The shank of the bit is indicated by the numeral 1 and is preferably constructed with a constricted axial duct, as 2, through tically completel inclosed which a liquid or fluid may beforced or drawn, to carry away the dust producedas an incident of the operation of the bit. The

said shank has at its working end, out

Wardly diverging ribs or facets, as 3, which i may be of any desired number and arrangement and between which clearance grooves, as 4, for the passa e of the aforesaid dust laden liquid or flui occur, The grooves .4 terminate at their outer ends in inversely curved facets, as 5, which extend forwardly in convergent relation for, a comparatively short distance. The inner edges of the facets 5 are indicated by the numeral 6 and are also the bounding edges of a recess or 0 ening 7 which is of inwardly tapering orm and extends axially of the drill, the inner end of the recess or opening 7 meeting and being axially alined with the duct 2. Theapices occurrin at the junction of the inversely curved acets 5 are sharpened to constitu'te radial cutting teeth, as 8, which extend from the corners formed by the. junction of the edges 6, to the median longitudinal lines of the ribs or facets 3.

The aforesaid recess or o ning7 is pracb; the surrounding portions of t e drill and consequently a maximum grinding and crushing area is afforded. Incidentally the ed es 6 may be and. preferably are sharpene to constitute cutting blades.

* The arrangement herein shown is preferred, though not obligatory. In the present arrangement-I employ four ribs or facets 3, a corresponding number of facets 5 and of teeth 8, a rectangular mouth bounded by .pyramidalform, as a consequence .of which a series of lines drawn at different angles through the center of. said opening by a comparison of the wi ths of the opening in the two lanes through which Figs. 3 and 4 are ta en. -The result of this is that the crushing pressure is gradually increased after its initial application and it follows that a. more efiicient crushing action is produced than would be the case if the crushing pressure were uniform.

In use, the teeth 8 will have a cutting action on an'annuhr area, the width of which is determined by the extent of said teeth. At the center of this annular cutting area a pinnacle is left and this pinnacle is worn away as the bit is advanced by will be of successivelyvar ying len hs, as 1s shown virtue of a combined cutting and crushing action, the cutting actionbeing produced by the edges 6 which take off the corners and sides of the pinnacle and the crushing action being produced by the tapered form of the opening or recess 7, the walls of which receive the said pinnacle in a wedge-like engagement of constantly increasing pressure which is exerted both axially by virtue of the tapered form of the recess and also laterally by virtue of the square cross section or pyramidal form of the recess.

It follows from the, foregoing description that the advantages stated in the introductory paragraphs are efficiently attained, since the device operates with a minimum cutting area and a consequent minimum resistance and with a maximum crushing area ofi'ering far less resistance than the equivalent cutting area found in the devices now known in the art. The structure incidentally preserves all the advantages of the known devices while adding thereto the novel advantages above set forth.

formation thereof throughout the cutting operation.

2. A drill bit having its working face cutting o eration and the recess having a suflicient egree of inward taper to produce the grinding down and crushing of the pinnacle continuously with the original formation thereof.

3. A drill bit having the working end of its shank formed Withx outwardly divergent facetsand with grooves alternating with the facets and terminating in outwardly converging facets, the apices of which are sharpened to consti'tute radial cutting teeth which extend to the longitudinal centers of the several divergent facets, the bit also having at its working end a centrally arranged inwardly tapering recess, the bounding edges of which are also the inner edges of the convergent facets, the radial teeth producing a pinnacle on the material in which the cut is being made continuously throughout the cutting operation and the recess having a sufiicient de ee of inward taper to produce the grindlng down and crushing of the pinnacle continuously with the original formation thereof. I

In testimony whereof I have hereunto set myhand. in presence of two subscribing witnesses. I

TERRiaNoE CONNELL."

Witnesses J. C. WHITBY, J. K. LEWIS.

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