US2736582A - Detachable rock drill bit - Google Patents

Description

Feb. 28, 1956 G. DIMITRIEFF 2,736,582

DETACHABLE ROCK DRILL BIT Filed Dec. 7, 1953 IN VEN TOR. Gearye Dim z'i'rz'cff United States Patent 2,736,582 DETACHABLE ROCK DRILL BIT George Dimltrielf, Noranda, Quebec, Canada Application December 7, 1953, Serial No. 396,559 1 Claim. (Cl. 287-126) This invention relates to detachable rock drill bits.

It is an object of this invention to provide a drill bit of the detachable type wherein means are provided for locking the drill steel or rod to the bit whereby substantially no deformation stresses are imposed on the bit to permit convenient re-use of the latter.

It is a further object to provide a drill bit of the detachable type wherein means are provided for more positively locking the drill rod thereto in simple drive fit relation to the bit while permitting convenient movement of such means to allow easy removal of the bit from the rod.

The invention will be described with reference to the accompanying drawing, in which:

Figure 1 is a sectional elevation of the bit in accordance with the invention with a drill rod associated therewith, and

Figure 2 is a transverse sectional Figure 1.

In the drawing, 1 is a drill bit of generally conventional form having a socket 2, which may be of plain cylindrical form. The drill rod is indicated at 3 ventional form having a cylindrical socket-engaging shank 4 of reduced cross-section and a tapered shoulder 5 at the juncture of the shank with the main portion of the drill rod.

The bit socket has a bottom wall surface 6, an interior side wall surface 7 approximately perpendicular to the bottom surface 6, and an exterior side wall surface 8 approximately parallel to interior surface 7. Surfaces 7 and 8 are thus parallel to the longitudinal axis of the bit. The cutting base portion 9 of the bit, as shown, flares outwardly from the exterior surface 8 at a point slightly above the bottom surface 6 of the socket. Thus, the depth of the exterior side wall surface 8 is slightly less than that of the interior side Wall surface 7.

In accordance with the invention, the bit socket wall is provided with a longitudinal slot 9, which preferably extends from the open mouth of the socket throughout substantially the entire depth of exterior surface 8. In other words, the slot 9 terminates in somewhat spaced relation to the bottom wall surface 6 of the socket.

Surrounding the socket and snugly fitting the exterior wall surface 8 thereof is a separate ring or annulus 10. The interior diameter of the ring 10 is approximately view on line 2-2 of and is also of con- 2,736,582 Patented Feb. 28, 1956 "ice equal to or but slightly greater than the normal exterior diameter of surface 8 to permit a snug, friction fit of the ring over the socket wall when the latter is free from engagement with the drill shank 4. The ring 10 has a depth approximately equal to that of exterior surface 8.

In use, the detached bit is provided as described with the ring 10 in place thereon, the snug fit of the ring being such that it rigidly retains its position on the socket wall during handling. The shank of the drill rod or steel is inserted in the socket and driven to the bottom thereof. As shown in Figure 1, just prior to the shank reaching the bottom of the socket, the shoulder 5 of the drill rod engages the mouth of the socket wall and thus the further movement of the shank from this point to the bottom of the socket will expand both the socket side wall and the ring 10. Because of the slot 9, the socket wall is substantially freely expandable without imposition of permanent deformation stresses thereon, such stresses being entirely imposed upon the ring 10, which, it will be apparent, very positively locks the bit to the shank.

When the bit requires sharpening, it is readily removed from the drill rod following removal of the ring 10 therefrom by driving such ring 10 off the socket wall. Since the socket wall of the bit has not been subjected to any deformation stresses, the bit is ready for re-use following sharpening simply by applying a new ring 10 thereto, the deformed ring being discarded.

I claim:

In a rock drill including a drill rod having a body portion, a cylindrical shank of less diameter than that of said body portion, and a tapered shoulder joining said body portion and shank, a drill bit having side and bottom walls forming a shank-receiving socket, the exterior surface of said side wall being substantially parallel to the longitudinal axis of the bit, said side wall having a single longitudinal slot therein extending from the mouth of the socket substantially throughout the depth of said exterior surface, and a ring surrounding said side wall and having a smooth exterior wall in completely overlying relation to said slot, the normal unexpanded interior diameter of said ring being approximately equal to the exterior diameter of said side wall whereby to hold said ring in snug position-retaining frictional engagement with said exterior surface, said exterior surface-and said ring each having a depth slightly less than the depth of said socket, the diameter of the socket being approximately equal to the diameter of said shank and said socket receiving said shank in press fitting engagement therewith, the depth of said socket being slightly greater than the length of said shank and the end of said side wall of the bit being engageable by said tapered shoulder to expand said side wall and ring.

References Cited in the file of this patent UNITED STATES PATENTS 1,360,897 Dailey Nov. 30, 1920 2,246,670 Earl June 24, 1941 2,354,656 Annesley Aug. 1, 1944

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