Hydraulic Control & Observation System 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 "Underwater special machinery equipments" of the project "Underwater backbone dry pipeline maintenance systems" 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 which is used to cut the launching of jacket (60 m depth, D = 40"～60") of the oil platform was designed.In this paper, the current status of the techniques of cutting the underwater pipes and that of the diamond wire saw in the worldwide was introduced. The gross structure of the machine was designed. The structure of the clamping device, depth-feed attachment, tangential-feed attachment and stretching device were designed and the main parts of them were selected.The hydraulic steering system of the diamond wire saw were designed and the main technical parameters of the power supply was calculated out and checked. The technique of electro-hydraulic proportion was applied to the hydraulic steering system and the electro-hydraulic proportional valve was selected. The mathematical model of valve control motor rate system was established and the dynamic characteristics of it were analyzed.The sensors used in the machine were selected to adapt the seabed work circumstance. The overground observation system was designed which picked the signals of sensors by program. 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.