Rotatable cutting bit assembly with cutting inserts

Details Rotatable cutting bit assembly with cutting inserts Rotatable cutting bit assembly with cutting inserts

2000-09-21

2001-11-13

Bagnell, David (Department: 3672)

Boring or penetrating the earth

Bit or bit element

Impact or percussion type

C175S426000, C175S418000

Reexamination Certificate

active

06315064

ABSTRACT:

BACKGROUND OF THE INVENTION
The expansion of an underground mine (e.g. a coal mine) requires digging a tunnel which initially has an unsupported roof. To stabilize and support the roof a roof bolt must be inserted into the roof to provide support. The operator must first drill holes in the roof through the use of a rotatable cutting bit or roof drill bit. A roof bolt is then inserted into each one of the holes.
A common roof drill bit design uses a cutting insert that has been brazed into a slot at the axially forward end of the roof drill bit body. U.S. Pat. No. 5,400,861 to Sheirer discloses various roof drill bits. U.S. Pat. No. 4,603,751 Erickson also discloses various roof drill bits. Applicants hereby incorporate U.S. Pat. No. 4,603,751 and U.S. Pat. No.5,400,861 by reference herein. In addition, the following catalogs published by Kennametal Inc. of Latrobe, Pa. (U.S.A.), which are hereby incorporated by reference herein, disclose roof drill bits: “Kennametal Mining Products”, Catalog A96-55(15)H6 (September 1996) [36 pages in length], and “Kennametal Mining Products” Catalog B92-75R(3)M5 (1992) [36 pages in length]. Furthermore, copending U.S. patent application Ser. No. 09/108,181 filed on Jul. 1, 1998 by Massa and Siddle and copending U.S. patent application Ser. No. 08/893,059 filed on Jul. 15, 1997 by Massa and Siddle disclose roof drill bits and cutting inserts for roof drill bits. These two patent applications (Ser. Nos. 08/893,059 and 09/108,181) are hereby incorporated by reference herein.
While the above roof drill bits and the cutting inserts for such roof drill bits have provided satisfactory performance characteristics, there remains room for improvement of the overall performance, as well as room for improvement of certain features of the roof drill bits and the cutting inserts therefor. In this regard, applicants believe that it would be desirable to provide for an improved rotatable cutting bit (e.g., roof drill bit), as well as the cutting insert for the rotatable cutting bit, that presents a cutting insert which has cutting edges with increased strength over earlier cutting inserts.
SUMMARY OF THE INVENTION
In one form thereof, the invention is a rotatable cutting bit for penetrating an earth formation. The rotatable cutting bit comprises an elongate bit body having a forward end and a rearward end. The bit body further defines a peripheral surface. The bit body has a first cutting insert affixed thereto at the axially forward end thereof. The first cutting insert has a first leading cutting edge and a first side clearance cutting edge. The first cutting insert is attached to the bit body so that the first side clearance cutting edge radially extends past the peripheral surface of the bit body so as to engage the earth formation. At least a portion of the first leading cutting edge is arcuate.
In another form thereof, the invention is a rotatable cutting bit for penetrating an earth formation. The rotatable cutting bit comprises an elongate bit body having a forward end and a rearward end. The bit body defines a peripheral surface. The bit body has a first cutting insert attached to the bit body at the axially forward end thereof. The first cutting insert presents a first leading cutting edge and a first side clearance cutting edge. The first cutting insert is attached to the bit body so that the first side clearance cutting edge radially extends past the peripheral surface of the bit body so as to engage the earth formation. The first leading cutting edge has a radially inward portion and a radially outward portion wherein the radially inward portion is disposed at an angle with respect to the radially outward portion.
In still another form thereof, the invention is a cutting insert for use in a rotatable cutting bit for the penetration of an earth formation wherein the cutting insert is disposed in a seat in the cutting bit with a peripheral surface. The cutting insert comprises a cutting insert body that has a top surface, a bevelled surface, and a leading surface. The leading surface and the top surface intersect so as to form a leading cutting edge at the intersection thereof. The bevelled surface and the leading surface intersect so as to form a side clearance cutting edge at the intersection thereof. The leading cutting edge has at least a portion thereof being arcuate.


REFERENCES:
patent: 4550791 (1985-11-01), Isakov
patent: 5139099 (1992-08-01), Hayashi et al.
patent: 5172775 (1992-12-01), Sheirer et al.
patent: 6044920 (2000-04-01), Massa et al.
patent: 6109377 (2000-08-01), Massa et al.

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