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What is the cause of the leakage of the hydraulic system of the injection molding machine?
1 Design factors
Selection of seals
The reliability of the hydraulic system depends to a large extent on the design of the hydraulic system seal and the selection of the seals. Due to the unreasonable selection of the seal structure in the design, the selection of the seals does not conform to the specifications, and the hydraulic oil and the selection of the seals are not considered in the design. The compatible type of sealing material, load condition, ultimate pressure, working speed, environmental temperature change, etc.
These all directly or indirectly cause hydraulic system leakage to varying degrees. In addition, due to the dust and impurities in the use environment of the injection molding machine, a suitable dust-proof seal should be selected in the design to prevent dust and other dirt from entering the system to damage the seal and contaminate the oil, thereby causing leakage.
Other design reasons
The design takes into account that the geometric accuracy and roughness of the moving surface is not comprehensive enough, and the strength of the connection part is not checked in the design, which will cause leakage in the work of the machine.
2 Manufacturing and assembly factors
Manufacturing factors:
All hydraulic components and sealing parts have strict dimensional tolerances, surface treatment, surface finish and shape tolerances.
If it is out of tolerance in the manufacturing process, such as: the piston radius of the cylinder, the depth or width of the seal groove, the size of the hole for the sealing ring is out of tolerance or due to processing problems, it has burrs or depressions, and the chrome plating falls off, etc. The parts will lose the sealing function due to deformation, scratches, crushing or uncompacting. It will cause the part itself to have a congenital leakage point, which will cause leakage after assembly or during use.
Assembly factors:
The hydraulic components should be free from savage operations during assembly. Excessive force will cause the parts to deform, especially the use of copper rods to hit the cylinder, sealing flange, etc.
The parts should be carefully inspected before assembly. When assembling, the parts should be dipped in a little hydraulic oil and gently pressed in. When cleaning, use diesel oil, especially rubber components such as seals, dust rings, and O-rings. If you use gasoline, make them It is easy to age and lose its original elasticity, thereby losing its sealing function.
3. Oil pollution and damage to parts
Gas pollution
At atmospheric pressure, about 10% of the air can be dissolved in the hydraulic oil. Under the high pressure of the hydraulic system, more air or gas will be dissolved in the oil.
The air forms bubbles in the oil. If the hydraulic support changes rapidly between high and low pressure in a very short time during the working process, the bubbles will generate high temperature on the high pressure side and burst on the low pressure side. If the hydraulic system components When there are pits and damage on the surface, the hydraulic oil will rush to the surface of the component at high speed to accelerate surface wear and cause leakage.
Particle pollution
The hydraulic cylinder is the main executive component of the hydraulic system of some injection molding machines. Because the piston rod is exposed and directly contacts the environment during the working process, although the guide sleeve is equipped with dust rings and seals, it is inevitable to bring dust and dirt. Into the hydraulic system, it accelerates the scratches and wear of the seals and piston rods, causing leakage, and particle contamination is one of the fastest factors in the damage of hydraulic components.
Water pollution
Due to the humidity of the working environment and other factors, water may enter the hydraulic system, and the water will react with the hydraulic oil to form acidic substances and sludge, reducing the lubricating performance of the hydraulic oil, accelerating the wear of the components, and the water will also cause the valve of the control valve. The rod is sticking, making the control valve difficult to operate and scratching the seal, causing leakage.
4 Parts damage
The seal is made of oil-resistant rubber and other materials. The aging, cracking, and damage caused by long-term use will cause system leakage. If the parts are damaged by collision during the working process, the sealing element will be scratched, causing leakage.
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Selection of seals
The reliability of the hydraulic system depends to a large extent on the design of the hydraulic system seal and the selection of the seals. Due to the unreasonable selection of the seal structure in the design, the selection of the seals does not conform to the specifications, and the hydraulic oil and the selection of the seals are not considered in the design. The compatible type of sealing material, load condition, ultimate pressure, working speed, environmental temperature change, etc.
These all directly or indirectly cause hydraulic system leakage to varying degrees. In addition, due to the dust and impurities in the use environment of the injection molding machine, a suitable dust-proof seal should be selected in the design to prevent dust and other dirt from entering the system to damage the seal and contaminate the oil, thereby causing leakage.
Other design reasons
The design takes into account that the geometric accuracy and roughness of the moving surface is not comprehensive enough, and the strength of the connection part is not checked in the design, which will cause leakage in the work of the machine.
2 Manufacturing and assembly factors
Manufacturing factors:
All hydraulic components and sealing parts have strict dimensional tolerances, surface treatment, surface finish and shape tolerances.
If it is out of tolerance in the manufacturing process, such as: the piston radius of the cylinder, the depth or width of the seal groove, the size of the hole for the sealing ring is out of tolerance or due to processing problems, it has burrs or depressions, and the chrome plating falls off, etc. The parts will lose the sealing function due to deformation, scratches, crushing or uncompacting. It will cause the part itself to have a congenital leakage point, which will cause leakage after assembly or during use.
Assembly factors:
The hydraulic components should be free from savage operations during assembly. Excessive force will cause the parts to deform, especially the use of copper rods to hit the cylinder, sealing flange, etc.
The parts should be carefully inspected before assembly. When assembling, the parts should be dipped in a little hydraulic oil and gently pressed in. When cleaning, use diesel oil, especially rubber components such as seals, dust rings, and O-rings. If you use gasoline, make them It is easy to age and lose its original elasticity, thereby losing its sealing function.
3. Oil pollution and damage to parts
Gas pollution
At atmospheric pressure, about 10% of the air can be dissolved in the hydraulic oil. Under the high pressure of the hydraulic system, more air or gas will be dissolved in the oil.
The air forms bubbles in the oil. If the hydraulic support changes rapidly between high and low pressure in a very short time during the working process, the bubbles will generate high temperature on the high pressure side and burst on the low pressure side. If the hydraulic system components When there are pits and damage on the surface, the hydraulic oil will rush to the surface of the component at high speed to accelerate surface wear and cause leakage.
Particle pollution
The hydraulic cylinder is the main executive component of the hydraulic system of some injection molding machines. Because the piston rod is exposed and directly contacts the environment during the working process, although the guide sleeve is equipped with dust rings and seals, it is inevitable to bring dust and dirt. Into the hydraulic system, it accelerates the scratches and wear of the seals and piston rods, causing leakage, and particle contamination is one of the fastest factors in the damage of hydraulic components.
Water pollution
Due to the humidity of the working environment and other factors, water may enter the hydraulic system, and the water will react with the hydraulic oil to form acidic substances and sludge, reducing the lubricating performance of the hydraulic oil, accelerating the wear of the components, and the water will also cause the valve of the control valve. The rod is sticking, making the control valve difficult to operate and scratching the seal, causing leakage.
4 Parts damage
The seal is made of oil-resistant rubber and other materials. The aging, cracking, and damage caused by long-term use will cause system leakage. If the parts are damaged by collision during the working process, the sealing element will be scratched, causing leakage.
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