Tool with wear-resistant cutting edge made of cubic boron nitride or polycrystalline cubic boron nitride, a method of manufacturing the tool and its use
First Claim
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1. A cutting tool, comprising:
- a tool holder;
a solid cutting body on said tool holder having a cutting edge on a surface of said body adapted to be pressed into cutting engagement with a workpiece to be machined, said cutting body being composed of a substrate selected from the group which consists of hard metal, a cutting ceramic, silicon nitride, silicon aluminum oxynitride, a cermet and tool steel, an initial layer on said substrate of a material selected from the group which consists of cubic boron nitride and polycrystalline cubic boron nitride, said initial layer having a thickness up to 10 μ
m; and
a dense, crack-free fine-crystalline oxide layer of a thickness of substantially 0.5 to 6μ
m on said cutting body overlying said initial layer on said surface of said cutting body formed with said edge, and covering at least part of said surface, said oxide layer consisting of at least one layer of a metal oxide.
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Abstract
For the improvement of the wear properties of tools with cutting edge of cubic boron nitride (CBN) or polycrystalline cubic boron nitride (PCBN) it is proposed to coat the CBN or PCBN body with a 0.5 to 6 μm thick layer of one or more oxides of the metals zirconium and/or yttrium and/or magnesium and/or titanium and/or aluminum, preferably aluminum oxide. The wear-resistant coating is deposited from the gas phase at gas-phase temperatures up to 800° C. Preferably for the coating the pulse-plasma CVD process is used. The so-coated tools are particularly suitable for the chip-forming precision machining of hard iron and hard steel materials.
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Citations
11 Claims
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1. A cutting tool, comprising:
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a tool holder; a solid cutting body on said tool holder having a cutting edge on a surface of said body adapted to be pressed into cutting engagement with a workpiece to be machined, said cutting body being composed of a substrate selected from the group which consists of hard metal, a cutting ceramic, silicon nitride, silicon aluminum oxynitride, a cermet and tool steel, an initial layer on said substrate of a material selected from the group which consists of cubic boron nitride and polycrystalline cubic boron nitride, said initial layer having a thickness up to 10 μ
m; anda dense, crack-free fine-crystalline oxide layer of a thickness of substantially 0.5 to 6μ
m on said cutting body overlying said initial layer on said surface of said cutting body formed with said edge, and covering at least part of said surface, said oxide layer consisting of at least one layer of a metal oxide. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A process for making a tool which comprises the steps of:
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(a) forming a one-piece solid cutting body adapted to be pressed into cutting engagement with a workpiece to be machined, said cutting body being composed of a substrate selected from the group which consists of hard metal, a cutting ceramic, silicon nitride, silicon aluminum oxynitride, a cermet and tool steel, an initial layer on said substrate of a material selected from the group which consists of cubic boron nitride and polycrystalline cubic boron nitride, said body forming a cutting edge, said initial layer having a thickness up to 10 μ
m;(b) applying a dense, crack-free fine-crystalline oxide layer of a thickness of substantially 0.5 to 6 μ
m on said cutting body overlying said initial layer on at least a portion of a surface of said cutting body formed with said edge by deposition from a gas phase at a low gas phase temperature range up to 800°
C., said oxide layer consisting of at least one layer of a metal oxide selected from the group which consists of magnesium, yttrium, titanium, zirconium and aluminum; and(c) mounting said body with said oxide layer thereon on a tool holder. - View Dependent Claims (9, 10)
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11. A method of machining a hard workpiece comprising the steps of:
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(a) forming a cutting tool with a wear-resistant cutting edge by (a1) forming a one-piece solid cutting body adapted to be pressed into cutting engagement with a workpiece to be machined, said cutting body being composed of a substrate selected from the group which consists of hard metal, a cutting ceramic, silicon nitride, silicon aluminum oxynitride, a cermet and tool steel, an initial layer on said substrate of a material selected from the group which consists of cubic boron nitride and polycrystalline cubic boron nitride, said body forming a cutting edge, said initial layer having a thickness up to 10 μ
m;(a2) applying a dense, crack-free fine-crystalline oxide layer of a thickness of substantially 0.5 to 6 μ
m on said cutting body overlying said initial layer on at least a portion of a surface of said cutting body formed with said edge by deposition from a gas phase at a low gas phase temperature range up to 800°
C., said oxide layer consisting of at least one layer of a metal oxide selected from the group which consists of magnesium, yttrium, titanium, zirconium and aluminum; and(a3) mounting said body with said oxide layer thereon on a tool holder; and (b) machining said hard workpiece with said cutting body.
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Specification