Double headed drill bit for a continuous coal mining machine

Abstract

A double headed drill bit for a cutting element carried on a rotary drum member of a continuous mining machine is provided according to the invention. The drill bit is formed from a length of hardened material and includes a first tapered bit portion extending from a point located at a first end of the length of hardened material toward a mid-portion of the length of hardened material, and a second tapered bit portion extending from a point located at a second end of the length of hardened material toward the mid-portion of the length of hardened material. The drill bit is removably positioned within the central opening of an annular sleeve located in a block member mounted on the rotary drum member. One of the first tapered bit portion or second tapered bit portion extends outwardly from the annular sleeve and the other of the first tapered bit portion or second tapered bit portion extends into the shank portion the annular sleeve. Positive retention means for securing the drill bit against longitudinal movement within the annular sleeve are also provided in the form of a retaining clip which engages an annular groove at the mid-portion of the drill bit.

Description

BACKGROUND OF THE INVENTIONField of the Invention[0001]The present invention relates to drill bits used in underground coal mining machines. More specifically, the present invention relates to a drill bit having two opposing bit heads and a new positive retention system for holding the bit in a sleeve.Description of the Related Art[0002]Continuous mining machines with drum type dislodging means are well-known and have been used for many years in the underground mining industry. A typical drum-type continuous mining machine 10 is shown in FIG. 1. The mining machine 10 includes a rotary drum member 12 carried on the forward end of a boom 14 of the continuous mining machine 10. The rotary drum member 12 carries multiple cutting elements 20, which are the subject matter of the present invention. A prior art cutting element 20 as best shown in FIG. 2 and FIG. 3 includes a block 22 which is mounted on the rotary drum member 12. The block 22 has a substantially cylindrical opening in a fac...

AI Technical Summary

Benefits of technology

The present invention aims to provide a drill bit that has a longer useful drilling life than conventional drill bits. The cutting element for a continuous mining machine includes a cylindrical end support that is inserted into the lower end of the sleeve. The outer surface of the cylindrical end support is rotatably received within the circular opening in the annular sleeve, and includes an annular groove for receiving a clip to limit its travel into the sleeve. The inner surface of the cylindrical end support has a large opening area defined by a first tapered section and a vertical wall. This design allows for easy removal of the drill bit if it breaks off at the shank.

Problems solved by technology

With each rotary drum member 12 carrying several dozen cutting elements 20, and with the drill bits 26 being subject to significant wear, there may be considerable cost in purchasing drill bits associated with a continuous mining machine such as the one shown in FIG. 1.

As high strength steel is required to provide a durable drill bit, it is not a present possible to significantly reduce the cost by choosing different materials.

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