Noise processing of injection molding machines

1. Pump or motor noise
(1) The phenomenon of suction is one of the main reasons for excessive pump noise. When the oil is mixed with air, it is easy to form cavitation phenomenon in its high-pressure area and propagate in the form of pressure waves, causing the oil to oscillate, resulting in cavitation noise in the hydraulic system of the injection molding machine. The main reasons are:
(1) The oil filter and oil inlet pipe of the hydraulic pump are blocked or the oil viscosity is too high, which can cause the vacuum at the oil inlet of the pump to be too high and make the air penetrate.
(2) The oil seal at the shaft end of the hydraulic pump is damaged, or the oil inlet pipe is poorly sealed, causing air to enter o
(2) The oil level of the oil tank is too low, so that the hydraulic pump inlet pipe is directly sucked out.
When the hydraulic pump has high noise in operation, the above parts should be inspected first, and the problem should be dealt with in time.
(2) Excessive wear of the internal components of the hydraulic pump, such as the wear and strain of the cylinder block and distribution plate of the pump, so that the leakage in the hydraulic pump is serious, and when the hydraulic pump outputs high pressure and small flow oil, it will produce flow pulsation, causing high hydraulic noise of the injection molding machine. At this time, the triangular groove can be appropriately enlarged to improve the influence of internal leakage on the output flow of the pump.
(3) The hydraulic pump distribution plate is also one of the important components that can easily cause hydraulic noise of the injection molding machine. During the use of the distribution plate, due to surface wear or oil sludge deposited in the opening of the unloading tank, the unloading tank will become shorter and change the unloading position, resulting in oil trapping phenomenon, which in turn causes higher noise. In the normal repair process, the distribution plate repaired by flat grinding will also have the consequences of shortening the unloading groove, and if it is not properly lengthened in time, it will also produce greater noise. In the assembly process, the large unloading groove of the distribution plate must be installed in the high-pressure cavity of the pump, and its sharp angle direction must be opposite to the direction of the cylinder block, otherwise it will also bring greater noise to the hydraulic system of the injection molding machine.
2. Noise of the relief valve
The relief valve is prone to produce high-frequency noise, mainly caused by the unstable performance of the pilot valve, that is, the noise caused by air vibration caused by the high-frequency oscillation of the pressure in the front cavity of the pilot valve. The main reasons are:
(1) Air is mixed with the oil, and cavitation is formed in the front cavity of the pilot valve and high-frequency noise is caused. At this time, the air should be exhausted in time and the outside air should be prevented from re-entering.
(2) The needle valve is overly worn due to frequent opening during use, so that the cone surface of the needle valve and the valve seat cannot be sealed, resulting in unstable pilot flow, pressure fluctuations and noise, which should be repaired or replaced in time.
(3) The pilot valve is unstable due to spring fatigue deformation, causing large pressure fluctuations and causing noise, and the spring should be replaced at this time.
3. Noise of hydraulic cylinder
(1) The oil is mixed with air or the air in the hydraulic cylinder is not completely exhausted, and the cavitation phenomenon is generated under the action of high pressure and causes greater noise. At this time, the air must be exhausted in time.
(2) The cylinder head oil seal is too tight or the piston rod is bent, and noise will also be generated due to other strength during movement. At this time, the oil seal or straightening piston rod must be replaced in time.
4. Pipeline noise
Excessive dead bends in the tubing or loose retention clips can also generate vibration and noise. Therefore, dead bends should be avoided as much as possible in the pipeline layout, and loose clips must be tightened in time.