| 摘要 |
PURPOSE:To strengthen the inside of a high pressure pipe by short-time treatment at ordinary temp. by controlling the internal pressure of a pressurized fluid introduced into the pipe to allow the inside of the pipe to yield plastically. CONSTITUTION:When a high pressure pipe such as the fuel jetting pipe of an engine or the oil pipe of a hydrauric machine is manufactured, the properly controlled internal pressure of a fluid is applied to the inside of the pipe with a hydraulic device or the like in the final stage to allow the inside of the pipe to yield plastically. The hardness of a part close to the inside is increased by work hardening and large compressive residual stress is produced along the inside. As a result, the inside of the pipe is considerably strengthened and the fatigue strength and cavitation resistance are considerably improved. By this method, the inside of the pipe can be strengthened without thermal deformation or embrittlement caused by conventional hardening.
|
