| Summary: | 碩士 === 國立臺灣大學 === 機械工程學研究所 === 93 === Titanium alloy is well known as one of the typical difficult-to-cut
materials. This thesis focuses on the effect of various cooling and lubricating
methods on machinability in turning Ti-6Al-4V titanium alloy. The appropriate
cutting fluid and its associated flow rate of the minimum quantity lubrication
(MQL) applied in the cutting process are determined first. Thereafter, four
types of cooling and lubrication methods during cutting are compared. They are
machining with the MQL technique, machining with flooded cutting fluid,
machining with a heat pipe embedded beneath the insert for heat removal, and
machining with the MQL technique together with the assistance of a heat pipe.
The most appropriate cooling and lubrication method is determined based on
the analysis of the resulting tool wear, cutting force, tool temperature, surface
finish and the chip morphology in cutting.
It is found that 20% water-based cutting fluid and a flow rate of 20ml/hr
are the proper combination of MQL. The use of MQL incorporates with a heat
pipe assisting heat removal results in minimum tool wear. The cutting speed in
turning Ti-6Al-4V titanium alloy can be increased from the normally
recommended 50-70 m/min to 90m/min. Hence improvement of machining
efficiency is expected.
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