Double-way Shock Absorber SJ

Product Detail

 Double-way Shock Absorber SJ

Technical Features

Model “SJ” Two-Way Shock Sub should be mounted on drill string which is near the bit. It can slow or sorbs the longitudinal bounce and peripheral torque impact of drill bit (drill string) simultaneously. It should realize the best fitting of drill pressure and rotation rate as to reduce the drill cost and improve the drilling efficiency. It can be used for the drill-in or coring of hard layer, gravel layer and soft-hard interlayer.

Working principle

The torsion of bottom hole will be changed with changes in bit structure ,formation and bit weight .When the drilling speed reaches up to a certain value ,torque and resonance will be happened to drill string .During rotation drilling , the lower part of drilling tool simultaneously bear axially pressure and torque. When bit weight exceed the limit value, the drilling tool will produce a transverse bending (it means lose steadiness) and torque can also make the drilling tool to lose steadiness to be turned into a twist shape. Two positions are very typical:

1. The lower bit is suddenly frozen and then torque bumping will be produced unless the cut down rotary energy.

2. Reversing operation in force.

The vertically damping unit is made of mandrel, piston assembly, annular space damping unit and liquid spring of working chamber . Working mechanism: To absorb or release the vibration energy of bit and drill string by means of compressible liquid producing spring deformation in working chamber under the function of pressure. The mandrel moves axially relative to outer barrel when liquid spring is in compression or explanation. Meanwhile ,the non-compressible liquid in damping chamber flows through damping space and produces a large number of friction heat so that some vibration and bumping energy are used up . The vertical bumping unit thus can absorb or reduce the drilling tools’ energy in vertical vibration and bumping.

The piston change-over unit is composed of spline outer barrel which is connected with piston by rectangular spline pair and the piston inner hole which is connected with mandrel by ladder-shaped spiral pair. Such a group unit can turn the torque vibration and impact load into vertical component of force in working chamber in a twinkling of an eye so that a constant torque is maintained on.

 

 

 

 

Technical Parameters

Model	O.D mm/in	I.D mm/in	Connection API	Max.Working load kN/lbf	Max.Working Torque kN·m/lbf·ft	Max.Drill pressure kN/lbf	Max.Working Stroke mm/in	Rigidity kN/cm	Overall Length Mm/in
SJ121	121 4-3/4	38 1-1/2	NC38	1000 224800	10 7300	300 67000	100 3-15/16	3.0~5.0	4208 165.66
SJ165	165 6-/2	48 1-7/8	NC46	1500 337200	15 11000	350 78600	120 4-3/4	3.0~5.0	5494 216.29
SJ203	203 8	65 2-1/2	6 5/8REG	2000 449000	20 14000	450 101000	120 4-3/4	3.0~5.0	6080 239.37
SJ254	254 10	71.4 2-3/4	8 5/8REG	2500 562000	25 18000	600 134000	120 4-3/4	3.0~5.0	6400 251.96
SJ279	279 11	76.2 3	8 5/8REG	3000 674000	30 22000	600 134000	160 6-1/4	3.0~5.0	5580 219.68

 Above list some models, other models also can be supplied as follows:SJ159（6-1/4"),SJ178(7"),SJ229(9").