As a key component in hydraulic cylinders, mining single-prop supports, hydraulic supports, and gun barrels, the quality of the cylinder's machining directly affects the lifespan and reliability of the entire product. Cylinder machining requires high precision, with an internal surface roughness requirement of Ra 0.4–0.8 μm, and stringent requirements for coaxiality and wear resistance. A fundamental characteristic of cylinders is deep-hole machining, which has always been a challenge for machining personnel.
Rollering, by leaving residual compressive stress on the surface layer, helps to close micro-cracks and hinders the propagation of corrosion. This improves surface corrosion resistance and delays the initiation or propagation of fatigue cracks, thus increasing the cylinder's fatigue strength. Through roll forming, a work-hardened layer is formed on the rolled surface, reducing the elastic and plastic deformation of the contact surfaces of the grinding pairs, thereby improving the wear resistance of the cylinder's inner wall and preventing burns caused by grinding. The reduced surface roughness after roll forming improves the fit properties.
Hydraulic cylinders are the most important components of engineering machinery. The traditional machining method is: broaching the cylinder body – precision boring the cylinder body – grinding the cylinder body. The roller burnishing method is: broaching the cylinder body – precision boring the cylinder body – roller burnishing the cylinder body. The process involves three parts, but in terms of time: grinding a 1-meter cylinder body takes approximately 1-2 days, while roller burnishing a 1-meter cylinder body takes approximately 10-30 minutes. The investment is also significant: grinding machines or honing machines cost tens of thousands to millions of dollars, while roller burnishing tools cost thousands to tens of thousands of dollars. After roller burnishing, the surface roughness of the hole decreases from Ra3.2-6.3 μm before burnishing to Ra0.4-0.8 μm, the surface hardness of the hole increases by about 30%, and the fatigue strength of the cylinder inner surface increases by 25%. If only the cylinder body is considered, the service life of the hydraulic cylinder increases by 2-3 times, and the boring and roller burnishing process is about 3 times more efficient than the grinding process. These data demonstrate that the roller burnishing process is highly efficient and can significantly improve the surface quality of the cylinder body.
After the cylinder is rolled, there are no sharp micro-cut edges on the surface. Long-term motion and friction will not damage the seals or sealing components, which is especially important in the hydraulic industry.
