Hideki Moriguchi

Material design method for the functionally graded cemented carbide tool

The aim of this study is to apply the concept of functionally graded materials (FGMs) to tool materials and to develop high-performance cutting tools. The requirement of the graded structure is that the surface is highly wear resistant cermet, and the inside is tough cemented carbide. Compressive residual stress was introduced to the material surface by grading the composition. To develop the new material, the cutting condition of broken cermet was investigated and their cutting temperature distribution was measured by a newly developed measuring method. Then Computer Aided Engineering (CAE) analysis was performed to calculate the generated thermal stress. The new material was developed with the aim to introduce the compressive residual stress over the calculated thermal stress. As a result developed tools demonstrated higher wear resistance, breakage resistance, thermal crack resistance and peeling resistance over those of conventional tools in the market.

Performance of Tungsten-Based Alloy Tool Developed for Friction Stir Welding of Austenitic Stainless Steel

As the cost-effective tool material, W-based alloys containing hard particles, exhibiting high strength, ductility, and thermal conductivity at high temperatures, were newly developed for FSW of austenitic stainless steel in this study. The W-based alloy tools containing various hard-particles were employed in FSW of type 304 austenitic stainless steel, and the wear behavior was examined. The W-based alloy tools coated by a ceramic exhibited the good performance during FSW, but the tool wear could not be completely prevented. Degree of the tool wear depended on the high-temperature strength, i.e., it decreased with increasing high-temperature strength. The tool wear was significantly suppressed in the W-based alloy with the higher high-temperature strength, and the tool shape was hardly changed even after the 20 m travel on the tool with 1.7 mm long probe.

Observations on Orthogonal Cutting Processes - Effect of Friction between Tool and Work Material -

In this paper, orthogonal cutting tests of alloy steel, aluminum alloy and Ti6Al4V have been carried out to consider the cutting mechanism from the viewpoint of friction between the tool and workpiece. The cutting processes were observed in detail using a high-speed video camera. The cutting process of alloy steel was greatly affected by its tribological properties compared with those of the other two work materials. In the cutting process of alloy steel, there were three stages in relation to the state of the tool rake face and temperature. The difference between non coated and coated tools was marked in the later stages. From the discussion on the experimental results, it is considered that the thrust force is suitable for representing the tribological properties between the tool and workpiece. It is concluded that the orthogonal cutting test is a good method for evaluating tribological properties between the tool and workpiece.

Influence of Cold Rolling and Annealing on the Damping Capacity of Iron Sintered Compacts, Infiltrated with Lead

In fluence of cold rolling and annealing on the damping capacity of Fe sintered compacts, infiltrated with Pb was investigated by measuring internal friction. Infiltration volume ratio of Pb in sintered Fe compacts and draft of the specimens were up to 31.6% and 40%, respectively, and annealing temperatures were mainly 473 K. Results obtained were as follows:(1) Internal friction of Fe sintered compacts, infiltrated with Pb increased with the increase of infiltration volume ratio of Pb. Work of cold rolling enhanced the internal friction of specimens remarkably, but in the case of low volume ratio of infiltrated Pb in Fe sintered compacts, the internal friction tended to saturate at a certain draft.(2) Ultimate tensile strength of the specimens increased with the increase of draft, showed a maximum value, and then decreased with the increase of draft. Maximum value of ultimate tensile strength of the specimen tend-ed to shift to higher draft with the increase of Pb infiltration volume ratio.(3) Internal friction of cold rolled Fe sintered compacts fell down to that before cold rolling with annealing time at 473 K. On the contrary, in the case of cold rolled Fe sintered compacts, infiltrated with Pb, higher inter-nal friction was retained to prolonged annealing time. The origin of decrease of internal friction by annealing is thought to be the recovery of internal stress in Fe matrix by cold rolling.(4) Internal friction of Fe sintered compact, infiltrated with 30 vol%Pb and cold rolled at 40% of draft was approximately the same as that of flaky graphite cast iron. Whereas, ultimate tensile strength of this specimen was comparatively lower value of approximately 13 kgf/mm2.

Influences of cold rolling and annealing on the internal friction of iron sintered compacts and lead infiltrated iron sintered compacts.

For the purpose of estimating the damping capacity of composite structure type lead infiltrated iron compacts, the internal friction of them and of Fe sintered compacts for a comparison were measured, and influences of cold rolling and annealing on the internal friction were also studied. Results obtained were as follows:(1) The internal friction of Fe sintered compacts increased with an increase of porosity of compacts up to about 26%. Beyond that, the internal friction was retained almost constant value regardless of an increase of porosity of compacts. The internal friction of Fe sintered compacts could be enhanced remarkably by the rolling. But the enhanced internal friction was thermally unstable, and was reduced to the level of assintered condition after a short-time annealing.(2) The internal friction of Pb infiltrated Fe sintered compacts also increased with increasing both the Pb infiltration ratio and the rolling reduction. The internal friction of this material was thermally stable, i.e. the reduction ratio of internal friction was approximately one fifth after a prolonged annealing time. The damping mechanism of this material is thought to be mainly due to the absorption of vibration energy by the external friction at the interface between Fe skeleton and Pb infiltrant.