Research On Straightening Theory And Simulation Of Hydraulic Pressure System Of The Automatic Hydraulic Pressure Straightener

With the adoption of various strengthened oil-extraction measures, the working conditions of oil and water wells have become more and more deteriorated, and nearly all oil fields are now confronted with a universal problem: drill pipe failure which is increasingly aggravated year by year and brings about enormous losses of manpower, material resources and financial resources in oil fields. Researches on the straightening methods of drill pipe have both theoretical and engineering significance.Drill pipe failure is a complex problem involved with material mechanics, solid mechanics, fluid mechanics and material strength theory etc. in some science and technology fields. In the simple views, drill pipe deformation or breakage is due to the unbalance of the crust stress fields, which is brought about by the operations such as water-injection andoil-extraction. In the thesis of a doctor----Research on theMechanism of Casing Failure of Oil and Water Wells by Fracture-Mechanical Methods, the mechanism of casing failure has been discussed. In this dissertation, the straightening methods of the drill pipe are researched in accordance with the drill pipe was bended forever, but not broken and could not be used up to snuff.Primary research items are as follows:1. We discover the deformations of drill pipe include twistand bend through research in the DaQing oil field. Drill pipes twisted severely out of section shape could not be straightened by good salted technician, so we study intensively how to straighten bended drill pipes.2. In common with drill pipe failure, drill pipe straightening problem is also a complex problem involved with material mechanics, elastic-plastic mechanics, material strength theory and mechanism etc. The straightening math model isdescribed and two pieces of principia are presented intengineering points of views, with which straightening problem of the hollow pole of long span and thin wall can be realized.3. The automatic hydraulic pressure straightening machine adopts force servomechanism as control systems. Some system analysis and simulation are introduced. It establishes the basis of practical design of automatic hydraulic pressure straightening machine.In practical engineering, pressing point kind of reverse-bend straightening machine by right of experiments of operators and handworks has been used, but its precise stroke of pressing down is very low and measure is out of focus. At present, there are not the kind of automatic hydraulic pressure straightening machine with big size (length 10m, wall thick 9mm, diameter 150mm)and high precise(linearity lOmm/m), so studying and manufacturing it has wide market foreground and important engineering significance in our country.Researches about straightening model and control system are confirmed by the theoretical results in the dissertation.It establishes the basis of design and manufacture of automatic hydraulic pressure straightening machine.