Tadahiro Wada

Temperatures of maximum density in a pressure range from 15 MPa to −15 MPa generated for water in a metal Berthelot tube

Water exhibits anomalous thermodynamic properties. For example, the specific heat capacity of water is at minimum at 36°C under atmospheric pressure. In order to investigate phase diagrams including thermodynamic meta-stable states, which are important to elucidate the anomalies, the temperatures of maximum density (TMDs) were estimated in a pressure range from +15 MPa to −15 MPa on the basis of data of temperatures and pressures measured for various densities of water in a metal Berthelot tube. The TMDs in the negative pressure region were not on an extrapolation of an equation of state for water. The trend was similar to that not observed by a Berthelot method of glass spiral capillaries but calculated from molecular dynamics computer simulations.

Tool Wear of Aluminum-Chromium Based Coated Cemented Carbide in Cutting Hardened Sintered Steel

Tool life in turning sintered steels is shorter than that in turning melted steels such as carbon steels. In order to identify an effective tool material for cutting hardened sintered steel, tool wear was experimentally investigated. Hardened sintered steel was turned with two kinds of PVD coated cemented carbide tools. The coating films used were (Ti,Al)N and (Al,Cr)N. The main results obtained are as follows: (1) The wear progress of the (Al,Cr)N coated cemented carbide tool was slower than that of the (Ti,Al)N coated cemented carbide tool. (2) Because the (Al,Cr)N coating film exhibited both higher hardness and higher oxidation temperature, the wear progress of the (Al,Cr)N coated cemented carbide became slower. (3) In cutting hardened sintered steel with (Al,Cr)N coated cemented carbide tool, there was little influence of the cutting speed on the tool wear within the range of the cutting speed from 0.5 m/s to 1.0 m/s.

Tool Wear of Aluminum/Chromium/Tungsten-Based-Coated Cemented Carbide in Cutting Hardened Sintered Steel

In order to improve both the scratch strength and the micro-hardness of (Al,Cr)N coating film, the cathode material of an aluminum/chromium/tungsten target was used in adding the tungsten (W) to the cathode material of the aluminum/chromium target. In this study, hardened sintered steel was turned with (Al60,Cr25,W15)N, (Al60,Cr25,W15)(C,N), (Al64,Cr28,W8)(C,N), (Al,Cr)N and (Ti,Al)N coated cemented carbide tools. The tool wear of the coated cemented carbide tool was experimentally investigated. The following results were obtained: (1) In cutting hardened sintered steel at the cutting speed of 0.42 m/s using the (Al60,Cr25,W15)N, the (Al60,Cr25,W15)(C,N), the (Al64,Cr28,W8)(C,N), the (Ti,Al)N and (Al,Cr)N coated tools, the wear progress of the (Al64,Cr28,W8)(C,N) coated tool became slowest among that of the five coated tools. (2) The wear progress of the (Al60,Cr25,W15)(C,N) coated tool was almost equivalent to that of the (Al64,Cr28,W8)(C,N) coated tool. However, at a high cutting speed of 1.67 m/s, the wear progress of the (Al60,Cr25,W16)(C,N) coated tool was faster than that of the (Al64,Cr28,W8)(C,N) coated tool.

PERFORMANCE OF TITANIUM-TUNGSTEN-SILICON-ALUMINUM BASED COATED CUTTING TOOLS

In order to determine an effective coating film for cutting carbon steels with a coated cemented carbide tool, tool wear was experimentally investigated. Low carbon steel (AISI 5120H steel) was turned with four kinds of physical vapor deposition (PVD) coated cemented carbide tools. The coating films used were TiN coating film and three kinds of titanium-tungsten-silicon-aluminum based coating films, namely (Ti,W,Si,Al)N, (Ti,W,Si,Al)C and (Ti,W,Si,Al)(C,N) coating film. (Ti,W,Si,Al)N, (Ti,W,Si,Al)C or (Ti,W,Si,Al)(C,N) is a new type of coating film. The following results were obtained: (1) The critical load of three kinds of titanium-tungsten-silicon-aluminum based coating films was higher than that of TiN coating film. (2) The hardness of three kinds of titanium-tungsten-silicon-aluminum based coating films was higher than that of TiN coating film. (3) In cutting low carbon steel, the wear progress of three kinds of titanium-tungsten-silicon-aluminum based coating film tools was slower than that of the TiN coated tool. (4) In the three kinds of titanium-tungsten-silicon-aluminum based coating films, the wear progress of the (Ti,W,Si,Al)N coated tool was the slowest.

Tool Wear of Titanium/Tungsten/Silicon/Aluminum-based-coated Solid Carbide Thread Milling Cutters in Thread Tapping of Chromium-Molybdenum Steel

resistance. A titanium/tungsten-based coating film, namely (Ti,W) N coating film, has been developed. A (Ti,W,Si)N coating film, which is a titanium/tungsten/silicon-based coating film, has also been developed. Furthermore, titanium/tungsten/ silicon/aluminum-based coating films, namely (Ti,W,Si,Al) N, (Ti,W,Si,Al)C, and (Ti,W,Si,Al)(C,N) coating films, have been developed. And, compared with commercial (Ti,Al)N, the tool wear width of the (Ti,W)N/(Ti,W,Si,Al)N-coated tool was smaller than that of the (Ti,Al)N-coated tool. However, it is not clear whether these coating films are effective tool materials for helical milling with a thread milling cutter. In this study, chromium-molybdenum steel was helical milled with two physical vapor deposition (PVD)-coated cemented carbide thread milling cutters in order to clarify effective tool materials for tapping chromium-molybdenum steel. The coating films used were (Ti,Al)N and (Ti,W)N/(Ti,W,Si,Al)N coating

Tool Wear of Aluminum/Chromium/Tungsten-Based-Coated Cemented Carbide in Cutting Hardened Steel

An aluminum/chromium based coating film, called (Al,Cr)N coating film, has been developed. This coating film has a slightly more inferior critical scratch load and micro-hardness. Therefore, to improve both the scratch strength and micro-hardness of the (Al,Cr)N coating film, the cathode material of an alumi-num/chromium/tungsten target was used in adding the tungsten (W) to the cathode material of the alumi-num/chromium target. To clarify the effectiveness of the aluminum/chromium/tungsten-based coating film, we measured the thickness, micro-hardness and critical scratch strength of aluminum/chromium/tungsten-based coating film formed on the surface of a substrate of cemented carbide ISO K10 formed by the arc ion plating process. The hardened steel ASTM D2 was turned with the (Al,Cr,W)N, (Al,Cr,W)(C,N), (Al,Cr)N and the (Ti,Al)N coated cemented carbide tools. The tool wear of the coated cemented carbide tools was ex-perimentally investigated. The following results were obtained: (1) The micro-hardness of the (Al,Cr,W)N or (Al,Cr,W)(C,N), (Al,Cr)N coating film was 3110 HV0.25N or 3080 HV0.25N, respectively. (2) The critical scratch load of the (Al,Cr,W)(C,N) coating film was 123 N, which was much higher than that of the (Al,Cr)N or (Ti,Al)N coating film. (3) In cutting the hardened steel using (Al,Cr,W)(C,N) and (Ti,Al)N coated carbide tools, the wear progress of the (Al,Cr,W)(C,N) coated carbide tool was almost equivalent to that of the (Ti,Al)N coated carbide tool. The above results clarify that the aluminum/chromium/tungsten-based coating film, which is a new type of coating film, has both high hardness and good adhesive strength, and can be used as a coating film of WC-Co cemented carbide cutting tools.

Tool Wear of Polycrystalline Cubic Boron Nitride Compact Tools in Cutting Hardened Steel

Using polycrystalline cubic boron nitride compact (cBN) tools, which have different cBN contents and cBN particle sizes, the influences of both the cBN content and the cBN particle size on tool wear in turning of hardened steel at various cutting speeds was experimentally investigated. Three types of cBN tools (a cBN content of 45-55% and 75%, and a cBN particle size of 0.5 μm and 5 μm, respectively) were tested. Furthermore, three kinds of chamfered and honed cutting edges were also used. The main results obtained are as follows: (1) In the case of the cBN tools with the same cBN particle size of 5.0 μm, the tool life of the cBN tool with a cBN content of 75% was longer than that of the cBN tool with a cBN content of 45% at low cutting speed. However, at high cutting speed, the tool life of the cBN tool with a cBN content of 75% was shorter. (2) The tool life of the cBN tool with both a cBN content of 55% and a cBN particle size of 0.5 μm was the longest. (3) The tool wear of cBN tools decreased with a decrease in chamfer width.

Phase Diagram of Thermotropic Liquid Crystal Including Negative Pressure Region Generated in Metal Berthelot Tube

Phase diagrams including absolute negative pressure regions of thermotropic liquid crystals give useful information on science and technology. A phase diagram was depicted for ca. 40mg of a thermotropic liquid crystal in a pressure vs. temperature (P-T) plane by the Berthelot method using a metal tube. N-I phase transitions occurred even under-10MPa, and a polymorphism of the crystalline phase was observed.

Cutting Performance of Turning Insert with Three-Arcs-Shaped Finishing Edge

In the turning of a shaft with a step of specified corner R, it is important whether the corner radiuses of the turning insert is the same as the specified corner R or lower than it. A turning tool with a large corner radius cannot adapt to cutting a shaft with a step of specified corner R. In this study, the surface roughness, cutting force, and tool wear were experimentally investigated in order to clarify the cutting performance of the turning insert with a three-arcs-shaped finishing edge. The machined surface of the insert with a three-arcs-shaped finishing edge was better than that of the normal insert. The wear progress of the insert with an arc-shaped finishing edge was slightly slower than that of the normal insert. The cutting force of the insert with an arc-shaped finishing edge was almost the same as that of the normal insert.

Cutting Performance of Diamond-Like Carbon Coated Tool in Cutting of Aluminum Alloys

In cutting aluminum alloy 6061, continuous chips have a negative influence on the machining operation. Usually, Pb is added in order to break continuous chips. However, from the standpoint of environmental protection, it is necessary to improve chip breakability without adding Pb. One effective measure is improving chip breakability by adding Si in aluminum alloy 6061. However, the influence of Si content on tool wear has not been fully examined. In this study, in order to clarify the influence of a diamond-like carbon (DLC) coating layer on cutting performance, aluminum alloys having different Si contents were turned. The substrate of the tool material was high speed steel (1.4%C). The chip configuration, cutting force and tool wear were experimentally investigated. The following results were obtained: (1) The DLC coating layer was effective for decreasing the cutting force. (2) In cutting Al-2mass%Si alloy, the wear progress of the DLC-coated tool was slower than that of the un-coated tool. The length of a chip with the DLC-coated tool was shorter than that with the un-coated tool.