Yoshio Fujimura

Optimum tool geometry of CBN tool for continuous turning of carburized steel

Abstract The optimum geometry of a CBN tool for continuous turning of a carburized steel bar was determined for the angle and width of negative land, the nose radius and the honing radius. Fine turning by a tool with such an optimum geometry could be fully substituted for a grinding process on the basis of tool life and roughness of the finished surface. Tool wear as a controlling factor of tool life was analyzed. Particularly in the initial wear stage, frequent chipping of the cutting edge strongly influenced the life of tools with small negative land angles.

Optimum cutting tool geometry when interrupted cutting carburized steel by CBN tool

Abstract Interrupted turning, a quite severe application for the CBN tool, was attempted. In the turning of a two-groove bar, gradual wear controlled the tool life. However tool failure determined the life in the turning of a spline shaft. The type of failure in the latter case changed depending on the way in which the tool collided with the tool tip—catastrophic damage could be avoided with substantial improvement of the tool life and surface roughness of the workpiece. For further improvements of the life, a new tool was developed having a land on the flank face. Turning with this new tool resulted in a prolonged life, as much as 26 times that of the conventional tool previously developed for continuous turning.

Microstructure and mechanical properties of sintered cubic boron nitride

Etude de la microstructure et des proprietes de c-BN en vue de son utilisation comme outil de coupe

On the Cutting Performance of TiC-Cr3C2 Compound Ceramics Tool (Part 2)

In recent years. many ceramics and cermet tools with various kinds of properties have appeared on the market. The purpose of this paper is to clarify the tool life of TiC-Cr3C2 compound ceramics and TiC-Al2O3 ceramics tool on the machining of alloy steel at high cutting speed. The tool life was studied and discussed upon both continuous and Intermittent cutting by turning. The cutting speed for examination was 200 m/min, 250 m/min and 300 m/min. The results obtained are as follows; (1) In continuous cutting, tool life of TiC-Cr3C2 compound and TiC-Al2O3 ceramics tool was larger than those of cermet and ceramics tools. (2) The wear mechanism of TiC-Cr3C2 compound ceramics tool was pile up micro chipping on the tool edge. (3) In intermittent cutting, TiC-Al2O3 ceramics tool was appeared the longest tool life. (4) Since TiC-Cr3C2 compound ceramic and TiC-Al2O3 ceramics tool shows good cutting performance to the alloy steel, it is considered the cermet tool will be replaced by these tools.

On the Cutting Performance of TiC-Cr3C2 Compound Ceramic Tool

In recent years, many ceramic and cermet tools with various kinds of properties have appeared on the market. The purpose of this paper is to clarify the tool life of TiC-Cr3C2 compound ceramic tool on the prototype for the machining of carbon steel at high cutting speed. The tool life was studied and discussed upon both continuous and intermittent cutting by turning. The cutting speed for examination was 250m/min and 300m/min.The results obtained are as follows;(1) In continuous cutting, tool life of TiC-Cr3C2 compound ceramic tool was larger than those of cermet and ceramic tools.(2) In intermittent cutting, the chamfer angle of 30°on the edge gives the longest tool life. In this case, the failure on the tool edge was caused by pile up of micro chipping.(3) Since TiC-Cr3C2 compound ceramic tool shows good cutting performance to the carbon steel, the cermet tool will be replaced by this tool.

On the Wear Mechanism Study of Coated Cemented Carbides Tool by CVD

The purpose of this paper is to clarify the wear mechanism which occurs at high cutting speed. The alloys tool of coated cemented carbides with Al2O3+TiC by CVD was studied and discussed from the point of view of the relationship between flank wear and the condition of the occurrence of deposited metals on the tool surface, obtained by cutting tests and dynamic diffusion tests. In cutting tests by turning, the cutting speed was varied from 150 m/min to 400 m/min. The contact planes of both rectangular samples in a dynamic diffusion tests, inclined in 10 degrees to the horizontal plane, were kept at high temperatures ranging from 973 K to 1473 K for 30 minutes in an argon-gas environment. The main results obtained are as follows :(1) The best machining conditions of this tool were in cutting speed from 200 m/min to 250 m/min, and feed from 0.25 mm/rev to 0.35 mm/rev. (2) At high cutting speed, much deposited metal was observed on the tool edge, and this metal decreased the machined surface accuracy. (3) In the dynamic diffusion tests, the deposition between the coated layer and the work piece occurred at temperature of 1073 K or more. The coated layer was chipped from the matrix of cemented carbides at high temperature of 1373 K or more.

Machining performance for machinable ceramics. (Part 5). Drilling.

In recent years, many glass ceramics with various kinds of properties have appeared on the market. These ceramics are used for a few mechanical and electronic parts. Glass ceramics consisting of fiuor-phlogopite can be machined with tight tolerance using conventional metalworking equipment and tools. The purpose of this paper is to study the shape of drill edge and to find the mechanism of chipping on drill key hole in cutting with high efficiency. The chipping size was discussed upon both examination in drilling and analysis with the finite element method. The tests of drilling mica-ceramics were performed with twist drill of high speed steel by milling.The main results obtained are as follow: (1) Cutting of high speed and feed had an important effect on chipping size of drill key hole. (2) The tip angle of 90°on drill resulted in small chipping size. (3) The worn tool increased chipping on machining surface. (4) A large thrust in drillingincreased chipping of exit side on hole.

A Study on the Crater Wear Mechanism of Cermet Tools

The purpose of this paper is to clarify the wear mechanism at high cutting speed where mutual diffusion at interface comes to active.The relation between the crater wear rate and the condition of diffusion layer by cutting test and dynamic diffusion test, for reference, was investigated and discussed. Combination of materials was cermet tool of TiC type to plain carbon steel of 0.45%C. In the cutting test by turning, cutting speed was varied from 2.5 m/s to 7.5 m/s. In the dynamic diffusion test, the contact planes of both samples inclined at 5 degrees under axial load, were kept at high temperature ranging from 1273 K to 1473 K for 30 minutes in argon gas environment. The surface of samples was observed and analyzed using SEM and EPMA. The main results obtained are as follows:(1) At a tool face temperature over 1300 K, the wear rate depends strongly upon the temperature.(2) In this circumstance, a Ti-rich layer on the worn surface of tool is observed, which is hard and a brittle layer of several um thick.(3) A model can be proposed in which the wear proceeds by the repetition of formation and tearing off of the layer.(4) The layer is produced as a result of diffusion at interface and squeeze of binding material of Ni by pressure.