Key Technology & Model Machine Research On Underwater Diamond Wire Saw

The underwater diamond wire saw for cutting the seabed oil and gas pipelines is a machine which can adapt the seabed work circumstance well and cut any metallic or nonmetallic materials as well as composite materials in a single operation. Compared with other underwater cutting machines, the diamond wire saw has many advantages such as low-cost, highly-efficient, reliable and so on, so it has been widely applied to engineering.The research works are supported by the subproject "The product design of HG-24J diamond wire saw" of the project "Underwater backbone dry pipeline maintenance systems" (Project number: 2002AA602012-l)which belongs to the special topic "Seabed pipeline restoration technologies" of the national "863" project important special items "Bohai big oilfields exploration and exploitation key technologies". In the paper, the underwater diamond wire saw was design, which is used to cut the Seabed pipeline that need of repair .The Seabed pipeline is from 12" to 24" which about 60m depth under the water.In this paper, the current status of the techniques of diamond wire saw in the worldwide was introduced. The gross structure of the machine was designed. The structure of depth-feed attachment, tangential-feed attachment, clamping device, and stretching device were account and designed. This paper also account the buoy flotage, the center of gravity and buoyancy of diamond wire saw.The hydraulic steering system of the diamond wire saw were designed .The technique of electro-hydraulic proportion was applied to the hydraulic steering system and the mathematical model of valve control motor rate system was established. The PID controller was applied to the electro-hydraulic proportion. The dynamic characteristics of valve control motor rate system were analyzed.The sensors used in the machine were design to adapt the seabed work circumstance ,these are strain sensor and waterproof coder. The flux sensor was selected. The over ground observation system was designed which can picked the signals of sensors and can control the diamond wire to cutting in automatism or manual manner. LCD was used as the interactive platform which insured the observation system display the working parameters accurately so that the working status of the underwater diamond wire saw could be monitored instantly.