Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3618683 A
Publication typeGrant
Publication dateNov 9, 1971
Filing dateDec 16, 1968
Priority dateDec 16, 1968
Publication numberUS 3618683 A, US 3618683A, US-A-3618683, US3618683 A, US3618683A
InventorsHughes Robert W
Original AssigneeIngersoll Rand Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Button bit
US 3618683 A
Abstract  available in
Images(1)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

United States Patent 8 3,101 ,934 8/1963 Poundstone 175/410 X 3,318,401 5/1967 Carbert 175/413 3,346,060 10/1967 Beyer 175/410 FOREIGN PATENTS 183,787 3/1963 Sweden 175/410 Primary Examiner1an A. Calvert Assistant Examiner-Richard E. Favreau Attorneys-David W. Tibbott, Carl R. l-lorten and Frank H.

Thomson ABSTRACT: A percussive rock drill bit of a type generally known in the art as a button bit wherein a plurality of wear-resistant metal inserts project from the working face of the drill bit. An elastomeric sleeve surrounds that portion of the sides of the insert which is embedded in the bit body. There is metal to metal contact be between the end of the insert and the bit body for transmitting blow energy from the bit body to the insert.

PATENTEDHUV 9 197i 3,618.6 8 3 f l E INVENTOR ROBERT W. HUGHES ATTORNEY BUTTON BIT This invention relates to rock drill bits and in particular to rock drill bits generally known in the art as button bitsand to a novel means for securing the wear-resistant inserts in the bit body.

Percussive rock drill bits include a bit body with a plurality of wear-resistant hard-metal inserts such as tungsten carbide projecting from the working face of the bit body. Button bits are a type of percussive rock drill bit in which there are a plu rality of generally cylindrical wear-resistant inserts embedded in the working face. The end of the insert which projects outwardly is rounded. Prior to this invention, button bits were manufactured by drilling aplurality of holes in the working face of the bit body. The tungsten carbide inserts wereplaced in the holes and secured therein bymeans of brazing or by a shrink fit. Close tolerances must be kept in order to insure that the inserts are held in place when a shrink fit or a brazing technique is used. The proper relationship between the hole diameter and the size of the carbide insert must be maintained. If the spacing is too large, a shrink fit will not hold the insert in the bit body. Thus, it is often necessary to use a selective carbide insert assembly technique to insure the proper spacial relation between the bit body and insert. If an insert is oversized, it is necessary to insert that carbide into anoversized hole. This increases labor costs andhence the cost ofthe bit.

An additional disadvantage of prior methods of securing a carbide insert in the bit bodyis that heat treatment of the bit body must be substantially eliminated. With the shrink fit method, the bit body is heated to expand the hole. The'insert is placed in the hole and the body is cooled. Any heat treatment of the bit body will be lost in this process. In general,the bit body must be kept soft. This reduces the wear capabilities of the bit body.

A further disadvantage of the present methods of securing the carbide inserts in the bit body is that if the insert should come loose from the bit body while the bit is being used in the field, the insert cannot be replaced in the field. If the insert is to be replaced in order to gain optimum performance from the bit, the bit must be returned to the factory for reconditioning and replacement of the missing insert.

With present methods of securing the insert in the bit body, fracture of the insert often occurs if placement is incorrect. It is believed that the rigid interface between the insert and the bit body which prevents any movement of the insert is a cause of many failures of the inserts,

SUMMARY It is therefore the principal object of this invention to provide means for mounting a hard-metal insert in a drill bit body which will overcome the aforementioned disadvantages of prior mounting arrangements.

It is a further object of this invention to provide means for mounting a hard-metal insert in a drill bit body which will reduce manufacturing costs.

It is another object of this invention to provide a drill bit which will permit increased tolerances to thereby reduce bit manufacturing costs.

It is a still further object of this invention to provide mounting means for the hard-metal insert of a drill bit which will permit heat treatment of the bit body.

It is a still further object of this invention to provide drill bit insert mounting means which provides a shock-absorbing function for the insert.

In general, the foregoing and other objects will be carried out by providing a cutting implement for use with a rock drilling machine comprising: a bit body having a working face at one end; said working face having a plurality of openings therein; a wear-resistant insert mounted in each of said openings so that there is intimate contact between one end of said insert and the bottom of the opening within which it is mounted; and an elastomeric sleeve positioned between the sides of said insert and said bit body.

BRIEF DESCRIPTION OF THE DRAWING Theinvention will be described in connection with the accompanying drawing wherein:

FIG. I is a sectional view of a rock drill bit embodying the present invention;

FIG. 2 is a fragmentary view on an enlarged scale of a portion of the drill bit of FIG. 1; and

FIG. 3 is a sectional view taken on the line 3-3 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 of the drawing there is shown a percussive drill bit generally indicated at l of the type and generally known in the art as a button bit. As is well known in the art, the bit is adapted to receive an impact from a drilling machine (not shown) and be rotated to thereby drill a hole. The bit is provided with a working face 2 and an axial passage 3 for conducting fiuid such as compressed air for blowing cuttings out of the hole being drilled.

The working face 2 of the bit 1' is provided with a plurality of blind bores 5 which are adapted to receive hard-metal inserts 10 made of a suitable material such as tungsten carbide.

conventionally, the drill bitis heated to expand the blind bores 5, the inserts 10 are placed in the bores 5 and the drill bit cooled. Contraction of the bit body around the insert secured the insert in place. By the present invention, the insert 10 is held in the bore 5 by means of an elastomeric sleeve 12. The sleeve surrounds that portion of the sidewalls of the inserts which-isembedded in the bit body I. The end wall 11 of the insert 10 remains in intimate contact with the bit body so that when the drill bit receives an impact from the drilling machine, blow energy may be transmitted from the bit body I to the insert 10.

The elastomeric sleeve I2 may be of'any resilient material such as neoprene or the like. Preferably, the sleeve 12 is bonded to the tungsten carbide insert 10. If desired, the sleeve 12 may also be cemented to the walls of the bore 5 by means of a suitable adhesive such as the expoxi-type adhesive.

The diameter of the bore 5 should be smaller than the free outside diameter of the sleeve 12 so that the sleeve 12 is compressed between the insert 10 and the walls of the bore 5. Dimensional tolerances of the hole 5 and insert 10 need not be as close as with prior art arrangements because the sleeve 12 will permit a larger or smaller clearance between the insert and bore than is permitted with prior arrangements. This will reduce manufacturing costs because the necessity of using selective insert assembling techniques can be substantially eliminated. The compressive preload of the sleeve 12 between the sidewalls of the insert 10 and the walls of the bore 5 retains the insert 10 in the bore 5. The sleeve 12 must be of sufficient thickness to retain the insert in the cavity by a friction fit and to provide sufficient flexibility to optimize the stresses in both the sleeve and the bore between the insert and the sleeve and between the sleeve and the bit body. The sleeve I2 serves three basic functions. First, it holds the insert in the bit body thereby eliminating the shrink fit or brazing techniques presently employed. Second, the sleeve 12 serves as a shock absorber tending to reduce failure of the insert. Third, the sleeve 12 serves to eliminate the high initial stresses in both the insert and the bit body which are normally associated with a shrink fit. With present methods of securing the insert in the bit body, if the insert moves a slight amount during impact, stresses in the insert will be increased tending to cause fracture of the insert. The resilient sleeve 12 will permit a slight movement of the insert 10 relative to the bit body 1 without increasing stresses in either the bit body or the insert and hence tend to reduce failure of the inserts.

By the present invention, it will be possible to place the insert in the bit body while the bit body is cold. This will permit the bit body to be heat-treated in the desired manner before the insert is placed in the bit. Since the bit body can be heattreated to the desired extent, a stronger bit body and thus longer lasting bit can be achieved. Prior methods did not permit heat treatment because of the heating required for the shrink fit process. The bit body could not be heat-treated after the insert were in place because the inserts would come loose from the bit body.

From the foregoing it should be apparent that the objects of this invention have been carried out. The tolerances can be reduced because the elastomeric sleeve will expand and contract an amount which will permit larger hole and insert size tolerances. Selective carbide insertion is eliminated. Heat treatment can be performed on the bit body thus insuring a longer lasting drill bit. Because a shrink fit or brazing is not required, the inserts can be field replaced with a tool which permits easy insertion of the insert and sleeve.

1 Claim:

1. A cutting implement for use with a rock drilling machine comprising:

a bit body having a working face at one end;

said working face having a plurality of openings therein;

a wear-resistant insert mounted in each of said openings so that there is intimate contact between one end of said insert and the bottom of the opening within which it is mounted; and

an elastomeric sleeve positioned only between the sides of said insert and said bit body.

2. The cutting implement of claim 1 wherein said elastomeric sleeve is bonded to said insert.

3. The cutting implement of claim 2 wherein said elastomeric sleeve is bonded to said bit body.

4. The cutting implement of claim 1 wherein said opening is a blind cylindrical bore having a diameter smaller than the free diameter of said sleeve.

5. The cutting implement of claim 4 wherein said sleeve is bonded to said insert.

6. A rock drill bit comprising:

a bit body having a working face at one end;

a plurality of button-type wear-resistant inserts each having one end and at least a portion of its sides mounted in said bit body and projecting outwardly from said working face, said one end directly contacting said body; and

a resilient sleeve surrounding each of said inserts and positioned only between the sides of said insert and said bit body.

7. The rock drill bit of claim 6 wherein said resilient sleeve is bonded to said insert.

8 The rock drill bit of claim 6 wherein the working face of said bit body is provided with a plurality of blind bores having a diameter smaller than the diameter of said resilient sleeve and each of said inserts and said sleeve are mounted in one of said bores.

9. The rock drill bit of claim 8 wherein said sleeve is bonded to said insert.

10. The rock drill bit of claim 9 wherein said sleeve is bonded to said bit body.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1522593 *Oct 13, 1919Jan 13, 1925Pickin Rowland ORotary drilling tool
US3101934 *Aug 31, 1959Aug 27, 1963Consolidation Coal CoResiliently mounted cutting tool
US3318401 *Feb 4, 1964May 9, 1967Tel E Lect Products IncAuger head
US3346060 *Dec 23, 1965Oct 10, 1967Rex Beyer LeamanRotary-air-percussion, stabilizer and reamer drill bit of its own true gauge
SE183787A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3693736 *Sep 4, 1969Sep 26, 1972Mission Mfg CoCutter insert for rock bits
US3771612 *Jul 17, 1972Nov 13, 1973Pacific Tooling Eng CoReplaceable wear-resistant element assembly
US3805364 *Jun 5, 1972Apr 23, 1974Mission Mfg CoMethod of mounting cutter inserts in bit bodies and removing the same therefrom
US3852874 *Dec 10, 1973Dec 10, 1974Smith Williston IncMethod of inserting buttons in a drilling head
US3970158 *Apr 28, 1975Jul 20, 1976Hughes Tool CompanyTooth loading for earth boring bits
US4014395 *Oct 14, 1975Mar 29, 1977Smith-Williston, Inc.Rock drill bit insert retaining sleeve assembly
US4069880 *May 24, 1973Jan 24, 1978Kennametal Inc.Excavation tool
US4149753 *Jun 29, 1977Apr 17, 1979Gewerkschaft Eisenhutte WestfaliaCutter bit assemblies
US4151889 *Jun 29, 1977May 1, 1979William ListerRock-drilling bit for percussion hammers
US4181187 *Feb 24, 1978Jan 1, 1980Sandvik AktiebolagRock drill bit with stress relief insert sockets
US4251113 *Oct 16, 1979Feb 17, 1981Mitin Leonid AHammer for breaking strong abrasive materials
US4289211 *Oct 11, 1979Sep 15, 1981Sandvik AktiebolagRock drill bit
US4382477 *Jan 9, 1981May 10, 1983Drilling & Service U.K. LimitedRotary drill bits
US4668118 *Sep 26, 1984May 26, 1987Siku GmbhTool
US4674802 *Aug 18, 1983Jun 23, 1987Kennametal, IncMulti-insert cutter bit
US4700790 *Feb 26, 1985Oct 20, 1987Nl Petroleum Products LimitedRotary drill bits
US4716976 *Oct 28, 1986Jan 5, 1988Kennametal Inc.Rotary percussion drill bit
US5678645 *Nov 13, 1995Oct 21, 1997Baker Hughes IncorporatedMechanically locked cutters and nozzles
US5906245 *Oct 21, 1997May 25, 1999Baker Hughes IncorporatedMechanically locked drill bit components
US6102142 *Dec 22, 1997Aug 15, 2000Total,Drilling tool with shock absorbers
US9551190Nov 30, 2012Jan 24, 2017Mitsubishi Materials CorporationExcavation tool
DE3019422A1 *May 21, 1980Dec 11, 1980Vedecko Vyzk Uhelny UstavMesser zum trennen von gestein
EP0154422A2 *Feb 11, 1985Sep 11, 1985Reed Tool Company LimitedImprovements in rotary drill bits
EP0154422A3 *Feb 11, 1985Jun 11, 1986Nl Petroleum Products LimitedImprovements in rotary drill bits
EP2787163A4 *Nov 30, 2012Dec 2, 2015Mitsubishi Materials CorpExcavation tool
Classifications
U.S. Classification175/426
International ClassificationE21B10/46, E21B10/56
Cooperative ClassificationE21B10/56
European ClassificationE21B10/56