Research On Manufacturing Engineering And Special Equipments Of The High Pressure-Resistant, Large-calibre And Thick-wall Pipe Fittings

There is a big market for high pressure, huge caliber and thick wall pipe fitting (elbow, tee, cap and reducer), while the lag in manufacturing technology and the lack of mature techniques and complete equipment set couldn't be ignored as well. Therefore, a set of equipments that focus on the fittings with high performance has been designed and produced in response to the situation mentioned before. Furthermore, by the use of numeral simulation and experimentation, a set of the high-performance pipe fitting manufacturing techniques on the basis of heat press and welds has been introduced as well.There are three problems mainly discussed in this paper: the move of work piece during the heat-pressing process of pipe fitting, the position- change during the heat-pressing process of pipe fitting, and the process of elbow welding techniques. Meanwhile, forging operators, pipe-end facing machines and automatic location-changing welding machine have been well designed and calculated.Since pipe fitting possesses great varieties and standards, all kinds of demands for the various working conditions have been taken into consideration when the forging operator is designed. There two designs that make the machine a multiple-use machine: one is the operating movement with 5～6 selections, the other is the "operating manipulator" fitting which is available for teardown and displacement. According to the requirement of pipe fitting pressing process, the functions and motions are analyzed roundly; the study of every motion's mode, order and time has greatly saved the operating time for the work piece moving from heater to forging presser, which insures the temperature for heat-pressing.The location-changing welding machine has a fan-cage-mixed structure. Meanwhile, the first quarter location-changing welding machine and the last quarter location-changing welding machine works together, not only simplifying the structure, weight, cost and manufacture difficulty, giving a solution to the welding of elbow inside cracks, but also actualizing continuous welding and making the work more efficient. According to the characteristic of the elbow welding and the last quarter location-changing welding machine, the author studied a new theory of location-changing; as a consequence, a location-changing welding machine which works in phase has been designed on the basis of parallelogram principle.Considering the heat sensitivity of pipeline steel, a working procedure wiping off the heat affected zone has been introduced. By milling groove, a new heat affected zone can be prevented from forming.Comparing with half-handcraft-manufactured equipment or home-made single-functional sets that are prevalent at present, the whole set of equipments which are highly automatized can reduce the labor intensity and improve the pipe fitting's quality. Therefore, the whole set of equipments not only provide a mighty support for the production of the high pressure, huge caliber and thick wall pipe fitting, but also support many large projects such as Mid-Asian pipeline project.