Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
2001-08-13
2003-02-11
McDonald, Rodney G. (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S192320, C204S192380, C427S523000, C427S524000, C427S531000, C427S534000, C427S540000, C427S331000
Reexamination Certificate
active
06517688
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a method of smoothing a diamond coating, and more particularly to such a method which makes it possible to efficiently and accurately smooth a diamond-coated body having a complicated, three-dimensional geometry.
2. Discussion of the Related Art
As one type of a cutting tool such as an end mill, a tap and a drill, there is proposed a diamond-coated cutting tool in which a tool substrate made of a cemented carbide or other material is coated with a diamond coating, as disclosed in JP-B2-2519037 (publication of Japanese Patent issued in 1996) by way of example. In the diamond-coated cutting tool disclosed in this Japanese Patent publication, the tool substrate is coated with the diamond coating in accordance with a CVD (chemical vapor deposition) method. The diamond coating of the disclosed tool consists of an aggregation of grown diamond crystals, each of which has a large grain size or diameter. The large diameter of each diamond crystal causes the outer surface of the diamond coating to have large pits and projections which are inevitably transferred onto a machined surface of a workpiece which is machined by the cutting tool, thereby making it difficult to obtain a required degree of smoothness of the machined surface. In the interest of improving the smoothness of the machine surface, there are proposed methods of smoothing the surface of the diamond coating, by using various techniques such as laser beam, ion beam, thermo-mechanical lapping and mechanical-chemical lapping, as described in an article entitled “A preliminary investigation of the effect of post-deposition polishing of diamond films on the machining behavior of diamond-coated cutting tools” in pages 921-929 of “DIAMOND AND RELATED MATERIALS Vol.4 (1995)”.
However, the polishing method with the laser is not adequate for efficiently polishing a drill, end mill or other body having a three-dimensional geometry, although the method with the laser generally provides a high polishing rate. The polishing method with the ion beam requires a time as long as tens of hours for polishing a body, due to its low polishing rate. The polishing method with the thermo-mechanical or mechanical-chemical lapping cannot serve for polishing a body having a complicated, three-dimensional geometry with pits and projections on its surface.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method which makes it possible to smooth a surface of a diamond coating of a diamond-coated body with high efficiency and precision even where the diamond-coated body has a complicated three-dimensional geometry. This object may be achieved according to any one of first through nineteenth aspects of this invention which are described below.
The first aspect of the invention provides a method of smoothing a surface of a diamond coating of a diamond-coated body, by using an arc-type ion plating device in which at least one target is disposed, the method comprising: a step of causing arc discharge between an anode, and a cathode which is provided by each of the above-described at least one target, whereby positive ions are emitted from the above-described at least one target; and a step of applying a negative bias voltage to the diamond-coated body which is disposed in the arc-type ion plating device, whereby the surface of the diamond coating is bombarded with the positive ions, so as to be smoothed by the bombardment of the positive ions against the surface of the diamond coating.
According to the second aspect of the invention, in the method defined in the first aspect of the invention, each of the above-described at least one target includes, as a main component thereof, an element which belongs to one of groups IIIa through IVb of the periodic table.
According to the third aspect of the invention, in the method defined in the second aspect of the invention, each of the above-described at least one target includes at least one of Ti, TiAl, SiC, V, Y, Al and Cr.
According to the fourth aspect of the invention, in the method defined in any one of the first through third aspects of the invention, the negative bias voltage has a value of 500-1500 V.
The fifth aspect of the invention provides a method of smoothing a surface of a diamond coating of a diamond-coated body, by using an arc-type ion plating device in which at least one metallic target is disposed, the method comprising: a step of causing arc discharge between an anode, and a cathode which is provided by each of the above-described at least one metallic target, whereby metallic ions are emitted from the above-described at least one metallic target; and a step of applying a negative bias voltage to the diamond-coated body which is disposed in the arc-type ion plating device, whereby the surface of the diamond coating is bombarded with the metallic ions, so as to be smoothed by the bombardment of the metallic ions against the surface of the diamond coating.
According to the sixth aspect of the invention, in the method defined in the fifth aspect of the invention, each of the above-described at least one metallic target includes, as a main component thereof, a metal which belongs to one of groups IIIa through IIIb of the periodic table.
According to the seventh aspect of the invention, in the method defined in the sixth aspect of the invention, each of the above-described at least one metallic target includes at least one of Ti, TiAl, V, Y, Al and Cr.
According to the eighth aspect of the invention, in the method defined in any one of the fifth through seventh aspects of the invention, the negative bias voltage has a value of 500-1500 V.
The ninth aspect of the invention provides a method of manufacturing a diamond-coated body which includes a substrate and a diamond coating disposed on the substrate, the method comprising: a coating forming step of forming the diamond coating on the substrate; and a surface smoothing step of smoothing a surface of the diamond coating, by using an arc-type ion plating device in which at least one target is disposed, wherein the surface smoothing step including: a step of causing arc discharge between an anode, and a cathode which is provided by each of the above-described at least one target, whereby positive ions are emitted from the above-described at least one target; and a step of applying a negative bias voltage to the diamond-coated body which is disposed in the arc-type ion plating device, whereby the surface of the diamond coating is bombarded with the positive ions, so as to be smoothed by the bombardment of the positive ions against the surface of the diamond coating.
According to the tenth aspect of the invention, in the method defined in the ninth aspect of the invention, the diamond-coated body consists of a machining tool which is to be moved relative to a workpiece, for thereby machining the workpiece.
According to the eleventh aspect of the invention, in the method defined in the ninth or tenth aspect of the invention, the diamond-coated body consists of a rotary cutting tool which is to be rotated about an axis thereof-relative to a workpiece, for thereby cutting the workpiece, and which has a rake face, a flank face and a cutting edge that is defined by an intersection of the rake face and the flank face, and wherein the cutting edge is three-dimensional.
The twelfth aspect of the invention provides a method of manufacturing a diamond- coated body which includes a substrate and a diamond coating disposed on the substrate, the method comprising: a coating forming step of forming the diamond coating on the substrate; and a surface smoothing step of smoothing a surface of the diamond coating, by using an arc-type ion plating device in which at least one metallic target is disposed, wherein the surface smoothing step including: a step of causing arc discharge between an anode, and a cathode which is provided by each of the above-described at least one metallic target, whereby metallic ions are emitted from the abov
Sakurai Masatoshi
Sugita Hiroaki
McDonald Rodney G.
Oliff & Berridg,e PLC
OSG Corporation
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