ジャッキアップ型リグ用脚保持機構付き昇降装置の開発

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Recently oil drilling activity tends to go towards deeper water and harsher environments, which requires severer design conditions for oil drilling rigs. For jack up rigs, one of the typical type of oil drilling rigs, the above trend requires enhanced capability, such as stability, soil bearing capacity, leg strength and leg holding capacity. The former three problems can be solved by proper configuration of rig main hull, legs and footings, however, it is difficult and uneconomical to obtain the larger holding capacity by enlarging jacking system or leg holding system independently. In this respect the jacking unit newly developed by Sumitomo Heavy Industries. Ltd. can integrate jacking system, automatic torque balancer and leg holding system. The unit is developed in combination with Sumitomo standard jack up rig, SU300H, for 300 feet water depth and hostile environment use. Jacking system is of electric driven rack and pinion type, rated 320 tonf per pinion and composed of 4 pinions. As a sophisticated high ratio planetary reduction gear is adopted for first reduction stage, no oil bath lubrication is required for second and third reduction stages. which minimize the maintenance work. Automatic torque balancer eliminating the dangerous manual torgue adjustment of jacking motor, which is inevitable in conventional units, can equalize the bearing loads among all pinions of the jacking system. The balancer can also adjust the load distribution among the pinions and stoppers when both work simultaneously under the hostile sea condition. Leg holding system is composed of 8 stoppers, each independently driven by electric motor with constant torque, which can compensate the unfairness of chord racks and the relative displacement between racks and stoppers. This system is furnished above the jacking system and functions solely or simultaneously with the jacking system. Consolidated leg holding capacity is 6000 tonf per unit when jacking system and leg holding system are simultaneously operated, which leads to enormous leg holding capacity for its compactness. A 6000 tonf capacity comes from the uneven load distribution among pinions and stoppers. Theoretical analysis was carried out to study the behavior of captioned jacking unit under the design load conditions, which showed fairly good agreement with the experimental results. A l/2. 5 scale experimental model weighing about 20 tonf was manufactured, tested in every aspect by the 3000 tonf load test rig, and the test was found satisfactory with the obtained results, such as elevating capacity, automatic torque balance and leg ho]ding capacity. The load test was focused on investigating the mechanical and structural characteristics, especially on the load distribution among 4 pinions and 8 stoppers under the towing condition with full length legs raised and operating condition.
社団法人日本船舶海洋工学会の論文

ジャッキアップ型リグ用脚保持機構付き昇降装置の開発

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