In the operation of the hydraulic cylinder, when the piston rod is affected by the oil pressure expansion and contraction, it often produces uneven speed phenomenon, accompanied by vibration and abnormal noise, so the whole hydraulic system will vibrate, but also make the host of other parts of the vibration also occurs, which is very common in the host of the debugging, and in the acceleration of this phenomenon will be relieved. This phenomenon is caused by the hydraulic system piping, but also often due to the vibration of the cylinder itself.
Low-speed crawling phenomenon occurs because there are two cavities in the cylinder with and without rods, in which the gas is mixed, and under the influence of pressure, its volume will change, and under high pressure conditions, there will be transient gas explosion, which will lead to unstable speed of the cylinder.
Inside the cylinder, the low-speed crawling caused by the uneven friction of the guide element, and the ordinary guide material of the hydraulic cylinder, non-metallic support ring, etc., especially the non-metallic support ring, the size of which is not uniform, and some non-metallic support ring will become larger or smaller with the change of oil temperature, that is, the dimensional stability in the oil is not good, which will lead to the change of the fit gap, resulting in the unstable speed of the cylinder.
Due to the material problem of the seals, it leads to the low-speed crawling of the hydraulic cylinder, which usually adopts butyl cyan rubber, polyurethane rubber, polytetrafluoroethylene and so on as the sealing material, and the friction coefficient between the material and the contact surface is affected due to the material's hardness, strength, and followness, etc. In addition, the fluctuation of the oil pressure in the sealing surface will lead to the change of contact pressure between the sealing area and the contact surface, which will then lead to the cylinder's speed change.
The processing accuracy of the inner wall of the hydraulic cylinder and the connecting rod surface is an important factor affecting its low-speed stability, especially the geometric accuracy, which has a great impact on the performance of the hydraulic cylinder, of which straightness is the most important, but in actual production is the most difficult to ensure.
Low-speed crawling due to the cylinder design clearance is unreasonable, the piston in the cylinder and the cylinder, the piston rod and the guide sleeve of the sliding fit clearance is too large, resulting in uneven force on the sliding surface, which leads to the low-speed crawling of the cylinder; if the sliding fit clearance is too small, coupled with the production of the parts have a tolerance, it may also lead to uneven force on the sliding surface, which leads to the low-speed crawling of the cylinder.
