Design and kinematics analysis of underwater guillotine saw for oil&gas pipe

Oil or gas was transferred to one place by pipeline after exploitation of ocean oil&gas resources. When an old pipeline was leaking, it must be repaired. The guillotine saw is a necessary tool for repairing underwater oil&gas pipes, and is used to cut off damaged offshore pipeline. It was composed of sine cutting mechanism, eccentric cam mechanism and spiral feed mechanism. According to its technique process of cutting pipe, kinematics model of the guillotine saw was proposed. The rotation center of principal axis acted as center of the coordinates, the whole kinematics model was deeply discussed and its simulation analyses were finished, such as movement contrail and cutting state of the tool. Total resultant movement was validated by simulation and underwater experiment. Analytical results showed that there were optimized parameters: cutting velocity v=314 mm/s, feed velocity v
_j
= 12.5 mm/min, height of lifting the saw blade in backhaul e = 8~10 mm, and e is determinated by synthetical factors of movement. Synchronously, experiment shows that work of the guillotine saw is reliable under the influence of current in shallow sea. So the kinematics model is applicable for offshore pipeline service. The guillotine saw can offer a service measure of underwater pipe for oil and gas transporting successfully.