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SJ Double-Way Shock Absorber
Application and benefit:
The SJ Type double-way shock absorber is used to dampen or eliminate both vertical and horizontal shock / vibration caused by the drill string. The primary benefit of shock absorption is that it helps to reduce damages to the drill bit and drilling tools, reduce drilling cost and enhance drilling efficiency.
Working principle
The torsion on the drill string at the bottom of the well bore changes with respect to the type of bit structure, ground formation and bit weight. During drilling operation, the lower portion of the drill tool needs to withstand both the axial pressure and torque. This causes the drill string to undergo both torque and resonance vibration when the drilling speed reaches a certain range of values. When weight on bit exceeds its critical value (buckling load limit), the drilling operation will normally be interrupted due to stick-slip or BHA whirl (backward or forward).This is because the drilling tool will become unstable due to high transverse vibration (bending motion) and high torsional vibration (torsional motion, twist on the rod).
The vertical damping unit is made of mandrel, piston assembly, annular space damping unit and a fluid working chamber. In this mechanism, the compressible fluid in the working chamber acts as a spring to absorb or release the vibrational energy of the drill bit and drill string. For example, under pressure the fluid can be compressed like a deformed spring. The mandrel moves axially relative to the outer barrel when the fluid is in compression or expansion. Meanwhile the absorbed vibrational energy will be dissipated as the non-compressible fluid in the damping chamber flows through the damping space creating a great amount of heat and friction. Thus the vertical damping unit can absorb and reduce the lateral and vertical vibrational energy in the drilling tools.
The piston change-over assembly helps to maintain constant torque on the drill stem by instantly converting the torsional vibration and impact load into a vertical force component in the working chamber. The unit is composed of the spline outer barrel which is connected with the piston via a pair of rectangular spline and the piston inner surface is connected with mandrel by a pair of ladder-shaped spiral spline.
Available model:
SJ46B SJ62C SJ64C SJ70C SJ80C SJ90C SJ94C
Specifications - SJ Double-Way Shock Absorber
1 Double-Way Shock Absorber SJ46B 121 38 110 -40~150 10 200 1000 4490 NC38 320
2 Double-Way Shock Absorber SJ62C 160 47 120 -40~150 15 340 1500 5193 NC46 550
3 Double-Way Shock Absorber SJ64C 165 47 120 -40~150 15 340 1500 5193 NC50 600
4 Double-Way Shock Absorber SJ70C 178 57 100 -40~150 15 400 1500 5620 NC50 700
5 Double-Way Shock Absorber SJ80C 203 64 120 -40~150 20 480 1960 5586 6 5/8 REG 1000
6 Double-Way Shock Absorber SJ90C 229 71 120 -40~150 20 540 1960 5460 7 5/8 REG 1300
7 Double-Way Shock Absorber SJ94C 241 71 120 -40~150 20 540 1960 5460 7 5/8 REG 1500
