How to detect and repair cylinder failure

For presses that control the cylinder clutch pressure by pneumatics, the pressurizing cylinder is an important component. Once it is damaged, the machine will not function properly.

Some time ago, the third combined pressure cylinder action of the Heidelberg SM74 machine was not in place. As a result, the impression cylinder could not be pressed. This resulted in the fact that the printed graphic was not lack of color, that is, the printing was false (that is, the text was false or the flowers were made), and it was not normal. produce. In the past, the problem was that the factory replaced the cylinder with a new one, according to Heidelberg engineers. However, the life span of the new parts is very short. In general, it will be damaged in 1 year or so. Each cylinder is very expensive, nearly 20,000 yuan, causing great losses to the factory.

In order to save money and solve problems, we decided to solve this problem ourselves. According to the phenomenon analysis, the judgment is caused by the cause of the cylinder itself and has nothing to do with the electrical part. So, remove the cylinder, use the hand to move both sides of the piston rod, found that the side of the force is large and small, the piston that is judged to have a small resistance may have problems. If the piston ring wears out, replace the piston ring with a new one, but it cannot be ruled out that the solenoid valve is damaged. In order to accurately determine whether the solenoid valve or the piston ring was out of order, I changed the solenoid valve that was considered damaged in the cylinder to a new one (ie, a solenoid valve without plugging). In addition, the two solenoid valves were swapped and tested for each other's position, and their resistance also changed. The original side where the resistance was small became larger and the larger side became smaller. It was installed on the machine and connected to the gas circuit. The anti-composite pressure test was applied. The problem was solved. It has been used until now and no such failure occurred again.

This determines that the problem lies in the two solenoid valves. As a result, the two solenoid valves were dismantled and inspected and the solenoid valve was found to be somewhat different in structure. One solenoid valve had a plug with a small hole at the air inlet and the other did not. Comparing with the cylinders of the original machine, it was found that the two solenoid valves of the original machine cylinder had a plug with a small hole (which regulates the air path), and the service life of the original machine cylinder was about 4 years. Now that there are plugged cylinders on single-sided solenoid valves, the longest service life is 1 year, and the shortest is only a few months.

Through the anatomical analysis of the bad cylinder, we found that there is no plugging on the cylinder solenoid valve, which can prevent the small holes from being blocked by dirty things during long-term use, so as to ensure that the exhaust gas is unobstructed. However, if some dust particles and oil slag enter the cylinder, it will cause the wear of the piston ring, aging, and inflexible action of the solenoid valve core, resulting in leakage of the cylinder and failure in normal operation. In addition, there is no plugging in the cylinder solenoid valve, exhaust though smooth, but the cylinder piston movement will not be smooth, and the sound is great, in the long run, it is easy to shorten the service life of the cylinder piston ring, it is also easy to cause damage to the outer seal ring, resulting in cylinder leakage gas.

The solution is to install a similar plug in the same position on the solenoid valve without adjusting the plug. This can not only prevent dirt from entering, but also ensure the smooth movement of the piston, thus ensuring the normal use of the cylinder and prolonging the service life of the cylinder.