Optimization Design Of Mud Pump Piston Biomimetic Surface And Research On Wear-resistance And Sealing

Mud pump, as the heart of drilling’s blood circulation system, is an important andindispensable drilling equipment, it has played a very important role for the mining ofmineral resources. However, Short life-span of piston seriously restricts mud pumpefficiency. Through field survey on the scene of the drilling mud pump running, theimprovement of mud pump piston optimization is the key to improve the efficiency ofdrilling. Piston cylinder failure is a major cause of the failure of drilling mud pump.The failure forms of drilling pump piston are mainly abrasive wear and crushed. Theinfluencing factors of drilling pump piston failure are pump pressure and speed, thefriction heat, the clearance between the piston and cylinder liner, mud, defectivecylinder liner.Biological in nature through the survival of the fittest, its surface structure isformed with some characteristics in the process of evolution. The earthworm is acommon soil animals, the surface of it is divided into most segments, each segment toform non smooth groove shape. This surface not only can reduce the contact area withthe soil, but also can secrete mucus. These characteristics have drag reductionfunction. Basing on the surface structure of earthworm, bionic groove and pit shapedrilling pump piston is designed in this paper. Processing mud pump piston wear testrig and the piston seal leakage test rig, optimize the bionic mud pump piston wearsealing performance test.According to the geological drilling with reciprocating pump test method ofnational standard requirements and the mud pump test rig parts, related equipmentdesign and production of indoor mud pump piston wear and life test rig. Design typeBW160bionic groove and pit shape mud pump piston wear life experiment wascarried out. The wear test results showed that the reasonable design of bionic mudpump piston can obviously improve the life of the piston. The highest life-spanincrease rate can amount to78.45%in this research. The greater impact factor of thepiston lifetime was the groove width, the smaller groove amount and groove spacing.In the same groove width and spacing, the piston life was increased with theincreasing of the amount of grooves. The piston lifetime increase was not obviouswhen groove shape bionic unit size was too small. But too larger bionic unit size could reduce the piston lifetime. The highest life-span increase rate of the dimplesshape bionic piston can amount to119%. The greatest impact factor of the life-spanwas the dimple diameter, medium impact factor was center angle of dimple, theminimum was depth. The relationship between the dimple diameter and life-span ofpiston was a parabola. The selection of dimple diameter was not too big or too small.The center angle of dimple decreases, life-span of piston increases. The life-span wasincreased with the increasing of the dimple depth in the reasonable range. Optimalbionic groove and pit piston comparison study showed that pit piston wear life wasbetter than groove piston. The wear rate of bionic piston on the same time was betterthan standard piston. In field drilling test, the bionic piston was designed according tothe results of bench test. The life-span of the bionic piston was1times that of thestandard piston.Design and build measurable leakage and friction of piston dynamic seal testdevice the bionic piston dynamic seal leakage test and standard of the piston.Dynamic seal leakage test results showed that the bionic piston leakage was smallerthan smooth piston leakage. The minimum leakage of groove width of3mm, thenumber of grooves4, the groove spacing of2mm was smooth piston leak amount24%.The greatest impact factor of the leakage was the groove width, medium impactfactor was groove amount, and the minimum was groove distance. The relationshipbetween the groove with and distance, and leakage was a parabola. The relationshipbetween groove amount and leakage was linear. The groove amount increased, andleakage decreased. The leakage of groove piston was less than pit piston, and itshowed that dynamic seal performance of groove piston was better. The highercontact pressure of groove than pit structure was reason of high the dynamic sealperformance. The piston thrust of bionic groove and pit shape were less or close thanthe smooth piston, it showed that Bionic structure improved the lubrication conditionand reduced the piston and cylinder liner friction resistance.Numerical analysis was made in bionic piston and standard piston. The resultsshowed that the equivalent stress value of root of bionic groove and pit piston wassmaller than standard piston. The equivalent stress of pit shape piston root wassmaller than groove shape piston. It showed that the pit shape structure obviouslyreduced the stress of piston root. The contact pressure of groove shape piston lip wasbigger than pit shape piston. It showed that groove shape structure could improve thepiston sealing performance. The equivalent stress of piston root decreased and thecontact pressure of piston lip increased with increasing groove width. The equivalent stress change was not obvious on piston root and lip with groove spacing changing.Groove number increase could decrease the equivalent stress of the piston root andincrease the contact pressure of surface piston. The equivalent stress of piston rootdecreased and the contact pressure of piston lip increased with increasing pit diameter.The equivalent stress on piston root and lip had a certain reduce with pit center Angledecreases. The equivalent stress change on piston root was very small and the surfacecontact pressure distribution was basically identical when pit depth was different. Thelubrication fluid flow velocity significantly slowed and fluid backflow phenomenonappeared on bionic piston surface, to guarantee more sufficient lubrication on thesurface of the piston.The wear sealing mechanism of bionic mud pump piston is summarized that thegroove and pit shape bionic units can increase lubricant storage space to improve theinterface lubrication conditions and reduce the friction resistance and heat of frictionpair. It can trap wear debris to avoid scratching friction pair again, and optimize thepiston stress and deformation. The bionic structure terminated the continuous furrows,to avoid mud to flow past the entire surface of the piston. The bionic piston canincrease the contact pressure on piston lip and enhance the piston adaptive capacityand prevent the piston eccentric wear, thereby improve the piston seal performance.