The sealing performance of the valve is critical to the control effect of the fluid medium and the safe operation of the system. And one of the important means to ensure the sealing performance of the valve is to grind its sealing surface. The main purpose of grinding is to eliminate the unevenness of the sealing surface, imperfections and small particles, so as to enhance the smoothness of the surface and smoothness, in order to achieve better sealing effect.
Basic Principles and Steps of Lapping
- Lapping Process Revealed
During the lapping process, the lapping tool is closely fitted to the valve sealing ring surface and carries out complex lapping motions along the fitted surface. At the same time, the abrasive is placed between the grinding tool and the sealing ring surface. As the two move relative to each other, the abrasive particles in the abrasive slides or rolls over the seal surface, removing a very thin layer of metal. It is important to note that grinding is not just a physical mechanical process, but is also accompanied by a chemical action. The oils and fats in the abrasives encourage the formation of an oxide film on the surface being processed, which in turn accelerates the grinding process. - The mystery of the grinding movement
In order to ensure the grinding effect, the grinding tool and the seal surface relative movement, each point on the seal to the relative sliding path of the grinding tool should be the same, and the direction of movement should be constantly changing. This kind of movement can effectively avoid the abrasive particles repeating the movement trajectory on the sealing ring, reduce the obvious abrasive marks, and then reduce the roughness of the surface. - Selection of grinding speed
The speed of grinding will directly affect the grinding efficiency. Usually, the grinding speed is between 10 and 240 meters/minute. However, for workpieces with high precision requirements, the grinding speed is generally not more than 30 meters/minute. The recommended grinding speed will vary depending on the sealing surface material of the valve. - Control of grinding pressure
Grinding efficiency will increase with the increase of grinding pressure, but too much pressure may lead to undesirable consequences. Therefore, grinding pressure is generally controlled between 0.01 and 0.4 MPa. In the rough grinding stage, a larger pressure value can be selected; while in the fine grinding stage, a smaller pressure value should be selected. - Consideration of grinding allowance
Since grinding is mainly a finishing process, the amount of cutting is small. The size of the grinding allowance depends on the machining accuracy and surface roughness of the previous process. Under the premise of ensuring the removal of machining traces from the previous process and correcting errors in the geometry of the seal, the smaller the grinding allowance, the better.
Specific steps of grinding - Preparation
First of all, you need to confirm the type and structure of the valve, and check the valve sealing surface damage and surface roughness. At the same time, prepare the grinding tools, grinding materials and the appropriate lubricant. - Cleaning the sealing surface
Clean the sealing surface with appropriate cleaning agent to remove the surface dirt and grease. This is an important step to ensure the accuracy of the grinding result. - Selection of grinding tools
According to the shape and material of the sealing surface of the valve, select the appropriate grinding tools, such as grinding wheels or abrasive discs. - Perform grinding operation
Fix the grinding tool on the grinding equipment and carry out appropriate grinding operations according to the shape and damage of the valve sealing surface. This can be done manually or mechanically assisted. - Control the degree of grinding
During the grinding process, the degree of grinding should be controlled according to the actual situation to ensure that the valve sealing surface is flat and smooth.
By following these grinding principles and steps, the sealing performance of the valve can be significantly improved to ensure the safe operation of the system.
