Research On Elastic Rail-type Pipeline Girth Weld Scannner

With the continued construction of oil and gas pipelines, the demand of the girth weld detection device for pipeline is increasing recently. With the automated ultrasonic testing (AUT) equipment in-depth study, having gradually been recognized for its reliability, it gradually replaces the radiation detector and becomes major equipment of Pipe Weld Inspection. A long-term dependence on imports of domestic AUT equipment, which restricts the country's major energy projects.Thus, the aim of this paper is to research and design an automated ultrasonic testing mechanism for the girth weld seam of pipelines, which originates from the National 863 Project-"Underwater reflow soldering technology for pipe in deep-sea and the localization technology research of AUT testing equipment". Following the completion of thesis work:The mechanical body and the the control system scheme of the scanner were determined based on the lucubration of the weld detection device at home and abroad. The mechanical body is composed of an elastic guideway, a mechanical carrier, an adjusting mechanism of the probe and the additional components. The static model of the mechanical device was established, the load formula of idler when the mechanical device at an arbitrary position was derived, which is the precondition of designing the clamping mechanism and the drive mechanism.The key components of scanner were analyzed and designed in this paper.The arc-envelope idler which is propitious to clamp was chosen as the clamping and driving scheme via the analysis and research of the arc-envelope idler and involute-envelope idler. The derailment analysis to the idler and the elastic guideway were completed based on the derailment criteria and the finite element contact analysis. To verify the friction drive schdme of the driving gear and the rack gear, the contact analysis of the gear and the rack gear, the plane and the camber were completed by means of the ANSYS software. The analysis results confirm the feasibility of the scheme and show that it has good performance compare to the traditional design experience.The speed servo control system drived in all directions and the communications scheme of this mechanism were designed based on the Microcontroller AT89C51. The mathematical model of the speed servo system was constructed and the simulation of the model was completed within the speed closed-loop control system. The accuracy, stability and dynamic response characteristic of the speed output were finally verified.