Kennametal 27mm 28mm Coal Mining Bit Roof Bit with Fully Spade and Inner Hex Body For specific cutting conditions

Kennametal 27mm 28mm Coal Mining Bit Roof Bit with Fully Spade and Inner Hex Body For specific cutting conditions

A rotatable cutting bit which comprises an elongate bit body which has a forward end and a rearward end and which defines a peripheral surface. The bit body contains a first seat at the axially forward end thereof. A first cutting insert is mechanically retained in the seat so as to present a clearance cutting edge which radially extends past the peripheral surface of the bit body. The first cutting insert has a leading cutting edge disposed at a lead angle between 50 degrees and 80 degrees.

A comparison of the roof drill bit of the specific embodiment of the invention tested against the KCV4-1 roof drill bit in different carbide grades shows that for all of the carbide grades tested the present invention had an increase in the penetration rate at a lesser average thrust. For the roof drill bit of the invention having a lower cobalt content and higher hardness than the carbide grade of the conventional roof drill bit, there was an increase in the penetration rate of about 48.5 percent at an average thrust which was meaningfully lower (2137 lbs. vs. 2619 lbs.). For the roof drill bit of the invention having a higher cobalt content and a similar hardness, the roof drill bit of the invention had an increase in the penetration rate of about 61.2 percent at a lower average thrust (2403 lbs. vs. 2619 lbs.). For the roof drill bit having a lower cobalt content and a higher hardness there was an increase in the average penetration rate of about 46.3 percent at a lower average thrust (2342 lbs. vs. 2619 lbs.).

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