High feed rate deep penetration drill

Reference Number: N 03-03

Inventors: Shepley, Barry E.

Owner: NISTAC

USPTO Link: 5174691

Invention Summary

To overcome the problem of high speed, high feed rate chip removal in deep hole drilling of nonferrous workpieces, the invention herein provides the following construction: (a) a shank for receiving rotary power, (b) an elongate bit extending from such shank coaxially aligned therewith and having a continuous single spiral land occupying one quadrant or less of said bit cross-section with a single spiral flute surrounding said land; (c) a cutting end portion extending integrally from said bit, said end portion having a conically-shaped end surface interrupted by diametrically opposed flutes, one of said flutes being a continuation of the bit flute thereby to define cutting edges, said edges further being defined by arcuate indentations resulting in a plurality of cusps to assist in breaking chips as they are formed; and (d) high pressure fluid means for cooling the bit, end portion, and chips during drilling and for hydrodynamically forcing the broken chips along said flutes, said high pressure fluid means extending centrally axially through said shank and end portion, terminating in exit openings in said end surface.

Preferably, the cutting end portion is restricted to an axial length less than the length associated with one revolution of the singular land or flute of the bit. Advantageously, the drill of this invention is used for drilling of openings which are in length at least 16 or 17 times the diameter of the opening to be drilled.

Preferably, the feed rate for the construction of this invention is at least 200 inches per minute and advantageously 260-412 inches per minute. It is preferable to operate such drill bits at speeds of at least 5000 rpm and advantageously at rotary speeds of 10,000 rpm. The diameter of the hole that may be drilled using this drill construction at such high speeds and feed rates preferably has a diameter of 1/2 inch or less.

High pressure fluid means may employ cooling fluid under a pressure in the range of 800 psi.

The composition of the workpiece may advantageously consist of all alloys of aluminum. The composition of the drill shank, bit, and end portion may be selected from the group of high speed steel and cemented carbides. The end portion may additionally contain ceramic tippets or implants.

Advantageously, the end portion of the drill may contain a ceramic insert in the form of a rectangular body, which body extend across the diameter of the drill bit so that the cutting edges will be primarily defined by the ceramic material.