US1552724A - Rotary drill bit - Google Patents

Description

Patented 8, 1925.

UNITED STATES mm o'rIs uoonn, or wnwoxn, OKLAHOMA.

ROTARY DRILL BIT.

Application filed November-.6, 1924. Serial No. 748,202.

provements in rotary rill bits of the socalled fish-tail type of construction, and it consists in the combinations, constructions and arrangements herein described and claimed.

As is well known, a drill bit of the above mentioned type of construction ordinarily is formed with the head thereof provided with a pair of integral depending cutter extensions which soon beoome dull in use, necessitating the removal of the entire bit for resharpening of the cutter portions thereof.

Ordinarily, it is necessary that the bit he 2 heated in a suitable furnace, and then provided with a sharp edge and tem red after the bit has become dull. It will appreciated that a considerable delay in the drilling operation may result froni the necessity 80 of removing the only availableibits for resharpening and repair or else a considerable supply of sharp bits must bekept on hand at all times, which would cause considerable expense.

An object of the present invention is to provide a drill bit of the character described which has simple, inexpensive and readily removable cutter members supported on the head of the drill bit and adapted to be re- 40 placed quickly and without the use of any special tools when required.

A further ob'ect of the invention is the provision of a rill bit of the character described which has means for cutting in ad- 46 vance of the bit head at the center of the drill bore as well as at theouter edge of the drill bore.

A further object of the invention isthe provision of a. drill bit having a central cut- 50 ter element mounted to rotate about an axis articularly to im-' which extends at right angles to the longitudmal axisg of the drill bit and being" adj ustable about its axis of rotation to vary the ortion of the cutting edge therwf that will (pbresented tothe work. 7

her objects and advantages will be apfparentfrom the following description, considered in conjunction with the accompanym drawmgs, in which,

igure 1 is a side elevation .of a drill bit 00 embodying the invention applied to thelower end of a drill stem, I

Figure 2 is an elevation of the structure shown in Figure 1, the view being at right angles to Figure 1, V

Figure 3 is a bottom plan view of the im proved drill bit, and

Figure 4' is a perspective group view ShOWlIl the cutter members of the drill bit and a s aft for supporting one of said cut- 10.

tom.

A drill bit embodying the invention has ahead 1' formed with a, reduced tapering axial attaching portion or shank 2 at the normally upper-end thereof. The attach- 7' ing ortion or shank 2 is shown as being provided with external screw threads for engaging with an internally screw threaded tapering axial socket 3 in the lower end of a drill stem 4, a shoulder 5 being defined so at the juncture of the shank 2 and the head 1 for engagement with the lower end of the drill steml-4 when the shank 2 has been screwed ti ht in the socket 3. Any thrust from the (f to the head 1 through the shoulder '5 without any undue strain of the threaded connection between the shank 2 and the drill stem 4,

The head 1 is provided at its lower end 00 with a 'pair of depending integral exten sions 6. The lower end portions of the respective extensions 6 are shown as extending laterally of the bit head. The inner side faces of, the respective extensions 6 are shown as lying in a vertical plane which extends centrally of the bit head while the outer faces of the extensions referably are convexly curved or rounded 0 at their lower ends and at their outer lateral edges as rill stem 4 thus will be imparted as 10 to conform to the inclination from the horizontal of the upper wall 8 of its seat. Each of the cutter plates 9 also has the lower end Wall thereof beveled as indicated at 11 and has the outer face thereof concavely curved as indicated at 12 so that the outer edge of the lower end wall of the cutter plate is a sharp cutting edge.

Each cutter blade 9 is secured in place in its seat by means of a bolt 13 and nut 14 or like fastening means so that the beveled upper end wall of the cutter plate will fit closely against the inclined upper wall of the seat and the lower end portion of the cutter plate will depend slightl below the level of the extension 6 on whic the cutter plate is supported. -The cutter plate thus will be held rigid with the extension 6 on which it is supported but can be removed quickly and easily for the purpose of replacement or repair. The thickness of the cutter plate preferably is such that the outer face thereof will be substantially flush with the inner face of the extension 6 on which it is supported. Each cutter plate also has the outer lateral wall thereof beveled as iicildicated at 15 to provide a lateral cutting e ge.

With the arrangement of depending extensions spaced apart as described in the foregoing, a vertical space or aperture will be defined at the lower end of the bit head as indicated at 16 between the inner lateral walls of the extensions 6. A horizontal shaft 17 extends transversely across the space 16 and has the end portions thereof supported in aligned seats indicated generall at 18 each of which may be formed part y in an inner face of one of the extensions 6 and partly in the adjacent face of the cutter plate 9 which is secured to that particular extension 6, the portion of the seat 18 that is formed in the extension 6 of course bein in the vertical wall of the rabbet 7 of sai extension so that the shaft 17 will be held against displacement from position to extend across the space 16 so long as the cutter plates 9 are held against displacement from the rabbets 7. Removal of the cutter plates 9 will. permit displacement of the shaft 17. A circular cutter 19 having the cutting edge thereof located intermediate its ends is su ported on the shaft 17 to rotate about t e axis of the latter and is held against axial ment of the ends of the cutter 19 with the inner lateral wall of the extension 6.

From the foregoing description of the various parts of the device, the operation thereof may be readily understood. The cutter plates 9 and the circular cutter 19 are made of suitable material, such as a high grade tool steel. These cutters are comparatively small and therefore can be replaced when required at slight expense. Moreover, the replacement of the cutters 9 and 19 or an one of these cutters can be effected quickly and easily withoutthe use of any special tools. The cutting edge portion of the drill cutter 19 depends below the lower cutting edges of the plates 9 and thus serves to start the drilling of a bore at the center of the latter before the lateral cutters 9 cut into the earth. The cutter 19 can be turned from a given position to present a different portion of the annular cutting edge thereof to the work when the portion of the cutting edge that has been in use has become dull.

Obviously, my invention is susceptible of embodiment in forms other than that illustrated in the accompanying drawings and I therefore consider as my own all such modifications and adaptations of the form of the device herein described as fairly fall within the scopeof the appended claims.

I claim:

1. A rotary drill bit comprising a head formed with a pair of spaced apart depending extensions at the lower end thereof, said extensions being located eccentrically of the bit head and having the inner faces thereof disposed in a vertical plane which'extends centrally of the bit head, each of said extensions having a seat in its inner face at the lower end thereof for a cutter plate, means for releasably securing said cutter plates to said extensions in engagement with their seats, and a circular cutter supported between said extensions for rotation about an axis which extends at right angles to the longitudinal axis of the bit head.

2. A rotary drill bit comprising a head formed with a pair of spaced apart depending extensions at the lower end thereof, said extensions being located eccentrically of the bit head and having the inner faces thereof disposed in a vertical plane which extends centrally of the bit head, each of said extensions having a seat in its inner face at the lower end thereof for a cutter plate, means for releasably securing said cutter plates to said extensions in engagement with their seats, a shaft extending between said of said shaft, said circular cutter dependin tensions and serving to clamp the opposite below the level of the lower edge of sai edge portions of said shaft to said extensions 10 cutter plates. i i so that the shaft extends across the space 3. A rotary drill bit comprising a head' between the extensions and a circular cutter 5 formed with a pair of spaced depending exsupported on said shaft for rotation between tensions'at the lower end thereof,- a shaft of said extensions.

greater length than the distance between said v extensions, cutter plates secured to said ex- RALPH OTIS MOORE.

Images