Leakage reason and treatment of hydraulic system of injection molding machine

Leakage causes and treatment of injection molding machine hydraulic system I. Overview Leakage is a common failure phenomenon of injection molding machine, mainly due to liquid pressure generated in the hydraulic components and piping flow and the gap between the components of the leak. In addition, poor working conditions of injection molding machine will have a certain impact on the seal. Hydraulic system in the event of leakage, will cause the system pressure can not build up, hydraulic oil leakage can also cause environmental pollution, affecting production or even have unforeseen serious consequences. The following for some of the factors that affect the leakage of hydraulic system injection molding machine to simply talk about the causes and countermeasures. Injection Molding Machine Second, the classification of leakage Injection molding machine hydraulic system leaks are mainly two, fixed seal leaks and movement seal leaks, fixed seal leaks mainly include the bottom of the cylinder, the connector joints, etc., Mainly include the cylinder piston rod parts, multi-valve stem and other parts. From the oil leakage can be divided into external leakage and internal leakage, external leakage mainly refers to the hydraulic oil leak from the system to the environment, the internal leakage is due to the existence of the pressure difference between the high and low pressure side and seal failure and other reasons, Hydraulic fluid flows from the high pressure side to the low pressure side in the system. Third, the reasons for the impact of leakage (a) design factors (1) the choice of seal The reliability of the hydraulic system depends largely on the design of the hydraulic system seal and seal selection, the design of the structure of the seal unreasonable , The selection of seals is not standard, did not take into account the design of hydraulic oil and sealing materials compatible with the type, load conditions, the ultimate pressure, the size of the work speed, changes in ambient temperature and so on. These are to varying degrees, directly or indirectly caused by hydraulic system leaks. In addition, due to the use of dust injection molding machine environment and impurities, so the design should choose a suitable dust seal to prevent dust and other dirt into the system to damage the seal, pollute the oil, resulting in leakage. (2) Other design reasons Considering that the geometric accuracy and roughness of the moving surface are not comprehensive enough and the strength of the connection part is not checked in the design, etc., these will cause leakage in the work of the machine. (B) the manufacture and assembly factors (1) manufacturing factors All hydraulic components and sealing components have strict dimensional tolerances, surface treatment, surface finish and form tolerance requirements. If the manufacturing process in the ultra-poor, for example: the cylinder piston radius, seal groove depth or width, sealing ring hole size or poor due to processing problems caused by a circle, itself has burrs or potholes, chrome off, Pieces will be deformed, scratched, crushed or inadvertently so that the loss of sealing function. Will make the part itself has a congenital leakage point, leakage occurs after assembly or during use. Injection molding machine hydraulic system (2) Assembly factors Hydraulic components should be installed in the brutal operation should be avoided, if excessive force will make the parts deformed, especially with a copper rod and other body beat, sealing flange, etc .; parts should be carefully checked before assembly , The assembly should be dipped in a small amount of hydraulic oil, gently press into the cleaning application of diesel, especially seals, dust rings, o-rings and other rubber components, if it is easy to use gasoline to lose the original elasticity of aging, Thus losing the sealing function. (C) oil pollution and damage parts (1) gas pollution At atmospheric pressure, hydraulic oil can dissolve about 10% of the air, under the high pressure in the hydraulic system, the oil will dissolve more air or gas . Air bubbles in the oil, if the hydraulic support in the work process in a very short period of time, the pressure changes rapidly between the high and low pressure will make bubbles in the high-pressure side of the high-temperature burst in the low-pressure side, if the hydraulic system components Pitting and damage on the surface, the hydraulic oil will rush to accelerate the surface of the component surface wear and tear, causing leakage. (2) Particulate Pollution Hydraulic cylinder is the main actuator of some hydraulic system of injection molding machine. Because the piston rod is directly exposed to the environment during the working process, although the guide sleeve is equipped with the wiper ring and the seal, etc., Dust, dirt into the hydraulic system to speed up the seals and piston rod scratches and wear, resulting in leakage, particle contamination is one of the fastest hydraulic components damage. (3) Water Pollution Due to wet working conditions and other factors, water may enter the hydraulic system. Water will react with hydraulic oil to form acidic substances and sludge, reduce the lubricating performance of hydraulic oil, accelerate the wear and tear of components, and water will also Resulting in control valve stem sticking, the control valve difficult to scratch the seal, resulting in leakage. (4) parts damage seals are made of oil-resistant rubber and other materials, due to prolonged use of aging, cracking, damage, etc. will cause system leakage. If the part is damaged during a collision by a working process, it can scratch the sealing element and cause a leak. Fourth, the main leakage control measures Leakage caused by injection molding machine hydraulic system is the result of many aspects of the combined effect of the existing technology and materials, to fundamentally eliminate the leakage of hydraulic injection molding machine is difficult to achieve. Only from the above factors affecting the hydraulic system leakage, take reasonable measures to minimize hydraulic system leakage. In the design and processing aspects should take full account of the important factors that affect the leakage seal groove design and processing. In addition, the choice of seal is also very important, if not fully consider the impact of the initial leakage factors, will bring immeasurable loss in the future production. Choose the correct assembly and repair methods, learn from past experience. For example, in the assembly of seals as much as possible the use of special tools, and coated with grease in the ring. In the hydraulic oil pollution control, we should start from the source of pollution to strengthen the control of pollution sources, but also to take effective filtration and periodic inspection of the quality of the oil. To cut off external factors (water, dust, particles, etc.) on the hydraulic cylinder pollution, can add some protective measures. In short, the prevention and control of leaks should be started comprehensively and comprehensively in order to be effective.