| Budget Amount *help |
¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1993: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Research Abstract |
Grinding was performed at a conventional wheel speed(32 m/s) using a diamond wheel, and a high pressure coolant was injected at the grinding point to achieve highly efficient and superior grinding of titanium alloys. In order to clarify the quality of the finished surface ground by this method, the surfaces of annealed materials of mainly Ti-6Al-4V alloys were ground under various grinding conditions, and measurements were taken of the roughness and hardness of the finished surface, the thickness of the layr deteriorated by grinding, residual stress, etc. The test results revealed the following. (1) The grinding wheel best suited for this grinding is a diamond wheel with tougher grains, a strong grain-bonding force, and pores in the surface of the grinding wheel which allow for permeation of the coolant. There is also an optimum grain size. (2) The quality of the finished surface is markedly improved with increased coolant pressure. (3) Compression-induced residual stress, whose distribution immediately under the finished surface was of the "compression type" was observed in the finished surface on which the experiment was made.
Next, in order to clarify the fatigue strength of the ground articles, fatigue test pieces of the annealed Ti-6Al-4V alloy plates were ground on both the obverse and reverse sides, and alternating plane-bending fatigue testw were then made on the test pieces. The results revealed the following. (1) The fatigue strength was highest with the aforementioned grinding wheel, and was higher than that of the annealed material. (2) The fatigue strength also increased when the coolant pressure and concentration were increased. (3) The residual stress from grinding and the thickness of the layr deteriorated by grinding influence the fatigue strength rather than the roughness of the finished surface.
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