浅谈海洋工程制管焊接新工艺的研究

在海洋工程的管线连接制造中,一般采用焊接的方式,其中钨极氩弧焊为主要的焊接方法,现阶段,随着海洋工程任务量的增加,焊接的工作量也变得十分巨大,一般情况下,管线长度超过4200m,焊口数量超过7200个,传统的焊接方法难以适应生产需求,因此需要改进,本文通过对新研制的四丝埋弧焊接工艺的分析,阐述其工艺特点与可行性。

NECESSITY AND METHOD OF PUBLIC PARTICIPATION IN STRATEGIC ENVIRONMENTAL ASSESSMENT OF CHINA

Public participation has been one of important problems in the strategic environmental assessment (SEA). In this paper, the origin and the present research-conditions of public participation in SEA were analyzed. And the necessity of public participation was illuminated from following three aspects: 1) the public participation in China′s SEA is a key method of gaining the public support; 2) the public participation is one important source of gaining information; 3) the public participation is a good way to overcome the obstruction in the traditional mechanism of making strategy decision. Effective public participation should be involved in the whole process of SEA, and the public participators should include the public representatives of the groups affected by environmental change, the specialists in SEA and relevant fields, persons who are interested in the strategy and media, and so on. Various methods of public participation in SEA, including the methods of obtaining information and information feedback or consultation, were discussed. Further, the function, the advantages and the disadvantages of each method were discussed in detail, too.

Boundary Control of Coupled Nonlinear Three Dimensional Marine Risers

This paper presents a design of boundary controllers implemented at the top end for global stabilization of a marine riser in a three dimensional space under environmental loadings. Based on the energy approach, nonlinear partial differential equations of motion, including bending-bending and longitudinal-bending couplings for the risers are derived. The couplings cause mutual effects between the three independent directions in the riser＇s motions, and make it difficult to minimize its vibrations. The Lyapunov direct method is employed to design the boundary controller. It is shown that the proposed boundary controllers can effectively reduce the riser＇s vibration. Stability analysis of the closed-loop system is performed using the Lyapunov direct method. Numerical simulations illustrate the results.

Investigation of a New Vortex-Induced Vibration Suppression Device in Laboratory Experiments

In order to mitigate vortex-induced vibration (VIV) of marine risers, especially to eliminate the phenomenon of frequency 'lock-in', a new suppression device of crescent-shaped flow spoiler was designed with seven different layout schemes. VIV model tests with six flow levels were conducted in a large wind-wave-current flume. In all cases, vibration responses in both in-line and cross-flow cases were measured. With the installation of suppression devices vibration frequency evolution of a riser was analyzed by Morlet wavelet transform. The principle of VIV suppression was interpreted through vibration characteristics. Fatigue life of the riser was calculated by the Palmgren-Miner rule. Compared with a bare riser, vibration of an outfitted riser with suppression devices disturbed the steady flow, the vibration amplitudes in the two flow directions were reduced, and the riser fatigue life was improved.

多机器人环缝焊接系统的设计

基于海洋工程制管业发展的需要,为了实现真正意义的全自动化高效焊接,从而提高焊接质量和焊接效率、改善工作环境,达到降低成本、节约能耗、提升公司技术竞争力的最终目标,在海洋工程制管生产线中引进多机器人协同控制双丝MIG焊接系统,应用于管件接长区工件外环缝的填充、盖面焊。本文根据海洋工程制管的行业现状,分析海洋工程制管技术的特点及发展瓶颈,深入研究了以多机器人协同运动控制方法,开发了多个机器人的双丝MIG高效焊接工艺,应用焊缝电弧跟踪以及接触式自动寻缝来满足不同尺寸管件的柔性化生产,从而实现了从管件来料至管件焊接完成的全程自动化机器人焊接中心。