The required cylinder barrel is a key part of hydraulic cylinder, and sometimes the direct acting component of hydraulic cylinder (when piston rod or plunger is fixed); the barrel, end cover and piston (plunger) form a sealed chamber for containing pressure oil and driving the load for acting; thus the barrel has requirements for strength, rigidity and sealing as below:
(1) The barrel should have sufficient strength to prevent permanent deformation under long-term rated operating pressure and short-term dynamic test pressure.
(2) The barrel should have sufficient rigidity to prevent bending caused by lateral force imposed by the piston and reacting force during installation.
(3) Reliable seal: The grade of dimensional tolerance and accuracy of geometric tolerance of cylinder inner surface, piston seal and supporting ring should be designed rationally to ensure reliable seal and reduce wear.
(4) The cylinder barrel to be welded should have good weldability to avoid cracking or excessive deformation after welding of flange, cylinder bottom or joint.
The above requirements should be guaranteed by proper selection of barrel material and rational process of manufacturing.
Material selection of hydraulic cylinder barrel:
(1) Generally, the annealed cold-drawn or hot-rolled seamless steel tube is used as the workblank of cylinder barrel. The semi-finished product with honed or accurately machined inner hole is available on the market, which may be cut into seamless steel tubes of the required length. Optional materials include 20#, 35#, 45# steel and 27SiMn alloy steel.
(2) Hydraulic cylinder barrel with operating temperature below -500C must be made of 35# or 45# steel and treated by thermal refining.
(3) The barrel welded with cylinder cover or flange should be made of ST52 steel and treated by thermal refining after pre-machining, while the cylinder not welded with other parts should be made of hardened and tempered CK45 or AISI4140 steel.
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