Study on the Fitting Strength between Ceramic and Metal with the Use of Insert Ring at Elevated Temperature : 1st Report, Proposal of the Method of the Shrink Fit with the Use of Insert Ring and Experimental Results

A new method of shrink fit between a ceramic shaft and an outer metal ring with the use of an insert ring has been developed in this paper. An insert ring, which has a higher coefficient of thermal expansion than that of the outer ring, was inserted between the ceramic shaft and the outer ring where the insert ring was cut in the radial direction into some pieces. The fitting strengths of these shrink fitted assemblies were measured from room temperature up to 600℃. The effect of number of cutting in the insert ring on the fitting strength at elevated temperature was researched. It was revealed that the cutting of the insert ring into over three pieces was requisite to ensure the fitting strength at elevated temperatures. We were able to design the fitting strength-temperature relationship by changing thickness of the insert ring in radial direction. For example, the fitting strength would increase when the insert ring was thick enough as the temperature was raised. And the fitting strength would decrease when the insert ring was thin enough as the temperature was raised. Expressions which estimate the fitting strengths were also developed in this paper