First, the general overview
Leakage is a common failure phenomenon of injection molding machine, mainly due to the liquid in the hydraulic components and piping flow pressure generated when the gap and the existence of various components such as leakage. Zhenye injection addition, the harsh working conditions of the injection molding machine The seal will have a certain impact on the 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 the production and even have unpredictable serious consequences.According to some of the impact of injection molding machine hydraulic system leakage The factors to simply talk about the causes and countermeasures.
Second, the classification of leakage
There are mainly two kinds of leakage in the hydraulic system of the injection molding machine. The leaks in the fixed seal and the leak in the moving seal, the leaked parts in the fixed seal mainly include the bottom of the cylinder and the joints of the pipe joints. The motion seal mainly includes the piston rod part of the cylinder, 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 leaks from the system to the environment, the internal leakage is due to the pressure difference between the high and low pressure side Existence and seal failure and other reasons, the hydraulic oil in the system from the high-pressure side to the low-pressure side.
Third, the impact of the reasons for the leak
(A) design factors
(1) the choice of seal
The dependability of the hydraulic system depends largely on the design of the hydraulic system and the choice of the seal. Due to the unreasonable selection of the seal structure in the design and the non-standard selection of the seal, the hydraulic oil and Sealing material compatibility type, load conditions, the ultimate pressure, the size of the work speed, ambient temperature changes, etc. These are in varying degrees, directly or indirectly caused by hydraulic system leakage.In addition, the injection molding machine environment with dust and impurities , So in the design should choose the appropriate dust seal to prevent dust and other dirt from entering the system to damage the seal, pollute the oil, resulting in leakage.
(2) other design reasons
Design taking into account the geometric accuracy and roughness of the moving surface is not comprehensive enough and in the design of the connection part of the strength check, etc., which will cause leakage in the work of the machine.
(B) manufacturing and assembly factors
(1) manufacturing factors
All hydraulic components and sealing components have strict dimensional tolerances, surface treatment, surface finish and geometric tolerances, etc. If the manufacturing process in the poor, such as: the cylinder piston radius, seal groove depth or width, the sealing ring Hole size or poor due to processing problems caused by the lost circle, itself has glitches or potholes, chrome off, the seal will be deformed, scratched, crushed or inadvertently and other phenomena make it lose the sealing function. Will make the part itself has a congenital leakage point, leakage occurs after assembly or during use.
(2) assembly factors
Hydraulic components should be installed in the brutal operation should be avoided, if over-force will make the parts deformed, especially with copper rods and other knock on the cylinder, sealing flanges; assembly parts should be carefully examined before assembly, parts should be dipped in a small hydraulic assembly Oil, lightly pressed, the application of diesel fuel cleaning, especially seals, dust rings, O-rings and other rubber components, if it is easy to use gasoline to lose its original elasticity of aging, thus losing the sealing function.
(C) oil pollution and parts damage
(1) gas pollution
Under atmospheric pressure, hydraulic oil can dissolve about 10% of the air, 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 rapid pressure changes between high and low pressure will make the bubble in the high-pressure side of the high-temperature burst in the low-pressure side, if the hydraulic system components have pits and damage, the hydraulic oil will rush at high speed The surface of the component accelerates the wear of the surface, causing a leak.
(2) particle pollution
Hydraulic cylinder as some of the main injection molding machine hydraulic actuator components, as the work process exposed directly outside the piston rod and the environment in contact with, although the guide sleeve is equipped with a dust ring and seals, but also inevitably the dust, dirt belt 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, may cause the water into the hydraulic system, the water will react with the hydraulic oil, the formation of acid and sludge, reducing the lubricating properties of hydraulic oil to speed up the wear and tear parts, water can also cause the control valve Rod sticking, the control valve difficult to scratch the seal, resulting in leakage.
(4) parts damage
The seal is made of oil-resistant rubber and other materials, due to aging for a long time, cracks, damage, etc. can cause system leakage .If the parts in the process of collision by damage, will scratch the sealing element, resulting in leakage.
Fourth, the main control measures leak
Leakage caused by the injection molding machine hydraulic system is the result of many comprehensive effects of the existing technology and materials, to fundamentally eliminate the leakage of injection molding machine hydraulic system is difficult to do. Only from the above impact on the hydraulic system Take reasonable measures to minimize the hydraulic system leakage in the design and processing aspects should take full account of the factors that affect the leakage of the seal groove design and processing.In addition, the choice of seal is also very important, if not at the beginning Taking full account of the influencing factors of leakage, it will bring immeasurable loss to the future production.Select the correct assembly and repair methods, learn from past experience.For example, as far as possible the use of special tools in the assembly of the seal, and in the seal In the control of the hydraulic oil pollution, we should start from the source of pollution, strengthen the control of pollution sources, but also take effective filtration measures and periodic inspection of the oil quality.In order to effectively cut off the external factors (water , Dust, particles, etc.) on the hydraulic cylinder pollution, can add some protective measures, etc. In short, the prevention and control of leakage should be comprehensive Hand, considering in order to achieve effective.