When the hot press is working, if the piston rod stop is not accurate, the thrust is insufficient, the speed drops, and the work is unstable, it is that the hot press can not drive the load. Let's look at the reasons for this:
1. Internal leakage of hydraulic cylinder. The internal leakage of hydraulic cylinder includes the leakage caused by excessive wear of hydraulic cylinder seal, piston rod and seal cover seal and piston seal. The reason for the seal leakage of piston rod and seal cover is that the seal is wrinkled, squeezed, torn, worn, aged, deteriorated, deformed, etc. at this time, a new seal shall be replaced. The main reasons for excessive wear of piston seal are improper adjustment of speed control valve, high back pressure, improper seal installation or hydraulic oil pollution. Secondly, there are foreign matters in the assembly and the quality of sealing material is not good. The result is that the action is slow and powerless. In serious cases, the piston and cylinder barrel will be damaged, resulting in "cylinder pulling". The treatment method is to adjust the speed control valve, make necessary operation and improvement according to the installation instructions; clean the filter or replace the filter element and hydraulic oil.
2. Hydraulic circuit leakage. Including the leakage of valve and hydraulic pipeline. The maintenance method is to check and eliminate the leakage of hydraulic connecting pipeline by operating the directional valve.
3. The hydraulic oil returns to the oil tank by-pass of the relief valve. If the overflow valve is stuck in the valve core by dirt, the relief valve will be normally open, and the hydraulic oil will flow back to the oil tank directly through the bypass of the overflow valve, resulting in no oil entering the hydraulic cylinder. If the load is too large, although the regulating pressure of the relief valve has reached the maximum rated value, the hydraulic cylinder still can not get the thrust required for continuous action and does not act. If the regulating pressure is low, the vertebral force required by the load can not be reached due to insufficient pressure, which shows that the thrust is insufficient. At this time, check and adjust the relief valve.