Sucker Rod Remanufacturing via Induction Heating
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Solution Overview
Problem
Existing methods for remanufacturing sucker rods often result in deformation, retention of geometrical defects, and reduced service life due to inadequate stress relief and geometric restoration, limiting the quality and efficiency of the reconditioned rods.
Innovation Solution
A method involving cleaning, non-visual inspection, categorization by steel class, heating to induce plastic deformation, shaping, shot peening, and final inspection, including induction heating and eddy current testing, to restore sucker rods to improved mechanical properties and geometric form.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cold working the rod's surface is performed to improve fatigue strength, then the fatigue strength and efficiency are improved, but the rod undergoes deformation due to tension and torsion
Solution Approach 1:
The patent applies hot working instead of cold working by heating the rod to austenite formation temperature range, fundamentally changing the temperature parameter to enable plastic deformation without the tensile stresses that cause deformation in cold working processes
Solution Approach 2:
The patent utilizes the phase transition of steel to austenite through heating, allowing the material to become more ductile and formable, then controls cooling to achieve desired shape while eliminating internal stresses that would cause deformation
2Reliability
If thermal treatment is applied to eliminate fatigue stress, then the stress is relieved, but the rod retains outside geometrical form defects
Solution Approach 1:
The patent combines stress relief and geometric restoration into a single integrated hot working process, where heating to austenite temperature simultaneously relieves internal stresses and enables plastic deformation to correct geometrical defects, rather than performing these as separate operations
3Strength
If shot peening is performed to improve fatigue strength, then the compressive residual stress layer is produced, but worn out or corrosion damaged rods retain all outside geometrical form defects
Solution Approach 1:
The patent performs preliminary hot working and geometric restoration before final heat treatment, correcting geometrical defects while the material is in its most formable state at elevated temperature, thereby preventing defect formation in the first place rather than attempting to address them afterward
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively enhances the fatigue strength and service life of sucker rods by removing defects, improving their geometric form, and increasing their usability through precise reshaping and stress relief, leading to higher quality reconditioned products.
Implementation Method 1
heating the rod until the sucker rod is able to undergo plastic deformation; heating the sucker rod to a temperature between about 900° C. and about 1300° C. Still further, said heating of the sucker rod may be accomplished by induction heating
Implementation Method 2
shaping the rod at a temperature wherein plastic deformation occurs; reheating the rod body up to a particular temperature and applying pressure in conditions favorable for plastic deformation
Implementation Method 3
cooling the rod
Implementation Method 4
the rods undergo shot peening. Shot peening is a cold working process used to produce a compressive residual stress layer and modify mechanical properties of metals
Implementation Method 5
performing a magnetic flux leakage inspection of the sucker rod
Implementation Method 6
induction heating and eddy current testing
Data Source
AI summary
The disclosure relates to the treatment of rods made of metal, particularly to the method of reclamation of used standard length rods, such as pump rods already used in the mechanical deep-pumping extraction of oil, as well as to the product made with the help of the mentioned method. The method of remanufacturing of standard length rods includes the reheating of the rod body to a temperature favorable for the plastic treatment of the rod such as plastic deformation of the rod body under pressure. Such methods allow for the reclamation of rods of the desired geometric form and enhancement of the mechanical properties of the remanufactured rod. The technical outcome of the claimed invention consists in the reclamation of rods of the desired geometric form and enhancement of the mechanical properties of the remanufactured rod.