National Shipbuilding Research Program. 1992 Ship Production Symposium Proceedings. Paper No. 7A-3: Measurement of Shipboard Piping Using a Portable Coordinate Measuring Machine (PCMM).

摘要

This paper describes available technology for a Portable Coordinate Measuring Machine (PCMM) which can be hand carried onboard naval vessels. The PCMM can perform measurements in confined spaces throughout a vessel on pipes, tubes and assemblies, as well as their end fittings and support devices. Al though portable, the PCMM can also be used in a stationary position for repetitive measurements. fit reduces the chance for leaks and equipment failure due to leaks. Hence, correct and accurate pipe measurements for pipe bending can reduce rework and cost. Present Measurement Method The PCMM is composed of four major components: an articulated six-axis digitizing arm, control unit, contact and non- contact probes, and tube and surface three-dimensional measurement software. The PCMM arm, lightly constructed, duplicates the articulation and reach of the human arm elements (shoulder, elbow, and wrist). various contact and non-contact measuring probes attach easily to the wrist of the machine. The following is a brief description of a typical manual method for measuring pipe aboard a naval vessel by naval shipyard personnel. Although there are many major elements involved in replacement of shipboard pipe (i.e.. measuring, templating, cutting, end prepping. bending, fitting-up, purging, and welding), this paper deals only with measurements and how the measurements are used to bend pipe. The PCMM control unit performs all the necessary mathematical and geometric calculations without the use of external computers or templates. It also contains sufficient data memory so that the operator is able to measure and Inspect geometric features such as points, lines, planes, arcs, circles, spheres, and cylinders, as well as defined surfaces along lofting lines, and complex surfaces at coordinate points.