Polycrystalline diamond cutting tool with coated body

摘要

A cutting tool for machining metal workpieces using polycrystalline diamond cutting surfaces with interspersed guide surfaces and chip evacuation surfaces. When machining holes in cast aluminum alloy workpieces it is found that aluminum machining chips adhere to guide surfaces and chip evacuation surfaces and mar the machined surface. It is found that when the guide and chip evacuation surfaces are coated with a diamond-like carbon material, aluminum chips do not mar the machined surfaces.

主权项

1. A rotatable hole-forming tool for machining aluminum alloy workpieces, the tool having an axis of rotation and a rounded external surface, the tool comprising:
an elongated one-piece tool body comprising a tool holder portion and a hole-forming portion, each centered on the axis of rotation of the tool; the hole-forming portion having a length for forming holes in workpieces, the hole-forming portion having a rounded external surface with one or more distinct regions along the hole-forming portion length, and an end surface for initial engagement with a workpiece, the rounded external surface of the hole-forming portion being formed with at least two inwardly-extending, opposing, V-shaped channels, each V-shaped channel being defined by two intersecting surfaces, a flat channel surface and a second channel surface, each of the channel surfaces being spaced apart at the external surface of the hole-forming portion and each surface extending inwardly from the external surface of the hole-making portion to intersect in an inner channel edge that extends parallel to, or along, the axis of rotation of the tool over a portion of the hole-forming portion of the tool body; the flat channel surface of each V-shaped channel having a first, brazed-on, aluminum-cutting, layer of sintered polycrystalline diamond (PCD), the first aluminum-cutting layer extending along a portion of the axial length of the first flat channel surface such that the first aluminum-cutting layer provides a drilling edge at an end surface for making a hole in a workpiece, and a reaming edge at the external surface of the hole-forming portion to size the hole formed by the drilling edge and to finish the surface of the hole; the second surface of each V-shaped channel intersecting the external surface of the hole-forming portion in an external surface region of the hole-making portion that is free of cutting edges or channels, and is diametrically smaller than the opposing cutting edge at the external surface of the hole-forming portion, the external surface region adjacent the edge of the second channel surface serving as a guide surface for the tool; and each aluminum-cutting PCD layer, each first and second channel surface, and the external surface of the hole-forming region of the tool being coated with a friction-reducing layer for lubricating the rotation of the tool in the workpiece and promoting the flow of aluminum chips, produced by the rotating cutting edges of the tool, along the surfaces of each channel toward the tool holder portion of the hole-forming tool, the thickness of the friction-reducing layer having a range of from one to three micrometers.