Hydraulic cylinder It is a hydraulic actuator used to convert hydraulic energy into mechanical energy, producing linear reciprocating motion (or oscillating motion). It features a simple structure and reliable operation. When employed for reciprocating motion, it eliminates the need for speed-reducing mechanisms, exhibits no transmission backlash, and ensures smooth movement, making it widely applicable in the hydraulic systems of various machines. The output force of a hydraulic cylinder is directly proportional to the effective area of the piston and the pressure differential across its two sides. A hydraulic cylinder typically consists of a cylinder barrel and cylinder head, a piston and piston rod, sealing elements, cushioning devices, and venting devices. While cushioning and venting devices vary depending on the specific application, the other components are essential.
 

　　What is the cushioning device of a hydraulic cylinder?

　　In hydraulic systems, when a hydraulic cylinder drives a mechanism of substantial mass, the cylinder attains significant kinetic energy at the end of its stroke. For instance, without deceleration, the piston and cylinder head may collide mechanically, resulting in impact, noise, and potential damage. To mitigate and prevent such hazards, deceleration devices can be incorporated into the hydraulic circuit, or cushioning devices can be installed inside the cylinder.

　　How are hydraulic cylinders machined?
 

　　Cylinders are key components of hydraulic cylinders, mining monolithic props, hydraulic supports, gun barrels, and other products; the quality of their machining directly affects the service life and reliability of the entire assembly. Cylinder machining is demanding, with internal surface roughness requirements of Ra 0.4–0.8 µm and stringent tolerances for coaxiality and wear resistance. A defining characteristic of cylinder bores is deep-hole machining, a process that has long posed significant challenges to machinists.

　　By employing roll forming, residual compressive stresses remain in the surface layer, which help to close surface microcracks and inhibit the propagation of corrosive damage. Consequently, this process enhances the surface’s corrosion resistance, delays the initiation or growth of fatigue cracks, and thereby improves the cylinder’s fatigue strength. Furthermore, roll forming induces a work‑hardened layer on the rolled surface, reducing elastic and plastic deformation at the grinding‑induced contact interface, thus improving the wear resistance of the cylinder’s inner wall and preventing grinding‑related surface damage. After rolling, the surface roughness is reduced, and the surface finish is significantly improved.