Yoshio Haruyama

Life improvement of TiN-duplex-treated tool steel by tempering

Effects of tempering the nitrided substrate on the life of TiN-duplex-treated tool steel are studied as a potential tool material for plasticity processes. Ring-on-block sliding tests are carried out against aluminum alloy without lubrication to evaluate the life of the TiN coating film under a high-load, low-speed condition where wear takes place predominantly. Results show that the tempering prolongs the TiN coating film life more than twofold. This is due to an increased fracture toughness of the substrate and improved adhesive strength of the coating-substrate interface, both suppressing wear of the TiN layer by scratching.

Characteristics of a hydrostatic bearing with a controlled compensating element

Abstract To improve the dynamic stiffness of a hydrostatic bearing, two kinds of compensating element composed of an air chamber and a capillary restrictor are attached to its pocket and positively and dynamically controlled by an electric controller. For one compensation the shaft displacement is fed back, for the other the varying load is fed back. Fundamental equations are derived and linearized. Then the transfer function is obtained. For sinusoidal or stepped loading the effects of these elements are examined experimentally and theoretically. As a result it is found that the dynamic characteristics of a hydrostatic bearing can be improved markedly by these compensating elements.

Comparison of the feedback source between shaft displacement and load variation in controlled bearings

Abstract There has been much research into improving the characteristics of an externally pressurized thrust bearing and this has used two methods: a flow control device and sensing mechanisms. This report uses the latter method and deals with an externally pressurized thrust gas bearing which has a variable flow control device controlled by two signals. One source of signal is shaft displacement and the other is load variation. The results predict that a bearing controlled by load variation has a much higher performance than that controlled by shaft displacement. In the experiment a bearing which feeds back load variation showed a high performance for shaft displacement over a wide range of frequencies.

Fluid inertia effects in a squeeze film. Evaluation of various approximate solutions in a large sinusoidal squeezing motion.

An analytic solution for the squeeze film flow of an incompressible Nowtonian fluid between circular parallel surfaces is presented. One surface undergoes sinusoidal oscillation toward the other. The solution is obtained in consideration of second order vibration. From a comparison of the conventional approximate solutions with the above one, and from experiment under condition of a large oscillation amplitude, it is concluded that the averaging approach in which the inertia term is averaged out across the film thickness gives fairly good approximations.