Drill containing minimum cutting material

A drill having a minimum volume of cutting material and being of the type having a shank of a material having a given hardness and provided with a plurality of longitudinally extending flutes, each flute having a radial extending wall surface and an angular wall surface which is angular with respect to the radius of the shank, the shank having two spaced-apart tapered tip portions, each tapered tip portion having a surface terminating in a point, the improvement comprising:

• a cutting element of cutting material having a hardness greater than said given hardness and, positioned between the two spaced-apart tapered tip portions of the shank and having two tip parts, each tip part of the cutting element being closely adjacent the point of one of the tapered tip portions of the shank so that each tip part of the cutting element is a smooth continuation of one of the tapered tip portions of the shank,
• the cutting element also having two axially and transversely extending surfaces, each axially and transversely extending surface having a portion in axial alignment with one of the radially extending wall surfaces of a flute of the shank, the cutting element also having two angular axially extending surfaces, each angular axially extending surface being in alignment with one of the angular wall surfaces of a flute of the shank, there thus being a smooth transition between the cutting element and the shank.

A drill having a minimum volume of cutting material and being of the type having a shank of a material having a given hardness and provided with a maximum diameter dimension and provided with a flute having an axially extending surface, the flute having a radially extending wall surface and an angular wall surface which is angular with respect to the radially extending wall surface, the shank having a pair of spaced-apart tapered tip portions, each of the tapered tip portions having a surface which terminates in a point, the improvement comprising:

• a flat cutting element of cutting material having a hardness greater than said given hardness and, positioned between the spaced-apart tapered tip portions of the shank, the cutting element having a transverse dimension substantially equal to the maximum diameter dimension of the shank, the cutting element having a pointed tip part closely adjacent the point of one of the tapered tip portions, the cutting element having a pair of main parallel transverse surfaces spaced-apart by a given major thickness dimension, the cutting element also having a pair of intermediate parallel surfaces between the main parallel surfaces and providing a cutting web therebetween, the cutting web having a pair of minor surfaces forming a minor thickness dimension less than the given major thickness dimension, the minor thickness dimension of the cutting element forming an axially extending surface which is in axial alignment with the axially extending surface of the flute of the shank, the cutting element also having an angular surface between one of the main transverse surfaces and one of the minor surfaces, the angular surface being in alignment with the angular wall surface of the flute, the cutting element also having a plurality of inclined surfaces, each of the inclined surfaces being adjacent and in alignment with a part of the surface of one of the tapered tip portions of the shank, there thus being a smooth transition between the shank and the cutting element.