Research and development of a self-centering clamping device for deep-water multifunctional pipeline repair machinery

When multifunctional pipeline repair machinery (MPRM) is used in the deep sea area, it is difficult to grip the pipeline and ensure concentricity between the cutter heads and the pipeline during its operation. In view of this, a new system of two-arm holding self-centering pipeline clamping device was proposed. The system is composed of two groups of parallelogram double-rocker mechanism and cranking block mechanism which are symmetrically distributed on the frame. The geometric parameter solutions of the clamping device were analyzed with motion and transmission as the constraints. A mechanical model was established to associate the friction torque of clamping points with the driving force. Clamping device and machinery were designed and manufactured for the Ø304.8–457.2 mm pipelines used in this test. ADAMS simulation experiments were conducted underwater, and the cutting and beveling tests were carried out onshore. The following results are achieved. First, the smaller the pipe diameter, the smaller the transmission angle of the oscillating slider mechanism; the longer the hydraulic cylinder stroke, the greater the transmission angle of the double rocker mechanism. Second, the driving force of the clamping device increases with the increase of the pipe diameter. When the diameter reaches 457.2 mm, the hydraulic cylinder driving force of the clamping device should be greater than 10219 N. Third, the feed rate of the cutters increases suddenly due to the slight shaking of the machinery which occurs at the beginning of the pipe cutting, so it is necessary to adopt a small feed rate. And fourth, onshore experiment results agree well with the theoretical design and simulation results, proving the rationality of the system. The research results in this paper provide technical basis for the research and development of similar engineering prototypes.