Research On CNC System For Cutting Pipes Of Offshore Platform

The CNC (Computer Numerical Control) System for cutting pipes of offshore platform is a key marine engineering equipment as the process quality of which has a direct impact on the reliability of platform. However, the pipes` intersecting curve cutting technology started late domestic and few corporations devoted which to construction of offshore platform[1]. The construction still relies on imported machines and related CNC systems home. At present, the only reported CNC System is designed for a imported cutting machine[2]. Especially, the cutting technics is obsolete which based on an approximate cutting method for matching the outdated pipe cutting machines with cutting torches rotated around single axis several years ago. This technics doesn't fully follows the geometric properties of surfaces; neither is conducive to surfaces'matching while being welded together nor keeping up with the increasing strength standard for tubular joints of deep-water and ultra-deep water offshore platform. Further, the construction of offshore platform is a vast project with the complex structure jointed by a large number of pipes who are manufactured from high-strength and expensive steel. However, the three-dimensional CNC pipe nesting technology is blank domestic[3]which can save steel while cutting pipes. Lack of this technology results in waste of mass steel as well as high unnecessary cost for the enterprises.This paper researches a CNC system for cutting pipes of offshore platform which matches domestic 5-axis CNC pipe cutting machine by cooperated with domestic CNC machine manufacturers. This CNC system implements a complete manufacturing process, including: obtains platform's geometric parameters from DXF files mainly and from complementarity module for special steel joints with components of non-column, accurate geometric modeling for joints, simulation for CNC pipe cutting and torch's motion control, CNC pipe nesting.Based on the fact that domestic CNC pipe cutting machines are equipped with cutting torches which rotate around two-axis generally today, this paper researches a new cutting technics which has improved the old one. An accurate geometric modeling is applied to the cutting technics of steel pipes of offshore platform which results in an accurate cutting technics which fully follows the geometric properties of surfaces instead of approximate technics obtained by traditional approximate modeling method. Further, the software simulation has showed that this new technics can effectively reduce the cutting length so as to improve the cutting speed and time efficiency. A kind of rotation mechanism for holding the cutting torch has been designed expressly to implement the new technics. This rotation mechanism can rotate with two axis while simple, light as well as reliable. More innovative, a CNC pipe nesting module has been worked out and been embedded in the system, easy handled while reliable of whose arithmetic and effective in reducing consumption of raw steel demonstrated by produced software.