Disassembly and assembly procedures of a small hydraulic press

　　1. before removing the cylinder of small hydraulic press, the hydraulic circuit shall be depressurized. Otherwise, when the oil pipe connected with the cylinder is loosened, the high-pressure oil in the circuit will be ejected rapidly. When the hydraulic pressure returns to discharge pressure, the handwheel or pressure regulating screw at overflow valve shall be loosened first to unload the pressure oil, then cut off the power supply or power source to stop the hydraulic device.

　　2. during disassembly, it is necessary to prevent damage to the screw thread at the top of piston rod, oil port thread, piston rod surface, inner wall of cylinder liner, etc. In order to prevent the slender parts such as piston rod from bending or deformation, the cushion support shall be used for balance during placement.

　　3. the disassembly of small hydraulic press is carried out in sequence. Because the cylinder structure and size of various hydraulic presses are different, the disassembly sequence is slightly different. Generally, drain the oil from the two cavities of the cylinder, then remove the cylinder head, and finally remove the piston and piston rod. When removing the cylinder head of hydraulic cylinder, special tools shall be used for the key or ring connected with internal key type, and flat shovel is forbidden; For flange end caps, they must be screwed out and hammering or prying is not allowed. When the piston and piston rod are difficult to draw out, they cannot be forced out. The reasons shall be found out before disassembly.

　　4. try to create conditions before and after disassembly to prevent the parts of hydraulic cylinder from being polluted by dust and impurities around. For example, disassembly should be carried out in a clean environment as much as possible; After removal, all parts shall be covered with plastic cloth, and do not cover with cotton cloth or other working cloth.

　　5. after the cylinder of small hydraulic press is disassembled, it is necessary to carefully check to determine which parts can be used continuously, which parts can be repaired and reused, and which parts must be replaced.

　　6. before assembly, all parts must be cleaned carefully.

　　7. the small hydraulic press should be installed with sealing devices at all places correctly.

　　8. special spanner shall be used when tightening screw connection parts, and torque moment shall meet the standard and standard requirements.

　　9. after the piston and piston rod are assembled, it is necessary to measure whether the coaxiality and straightness of the piston rod are out of tolerance.

　　10. after assembly, the piston assembly shall be free from block sense and uneven resistance when moving.

　　11. when small hydraulic pressure oil cylinder is installed on the main engine, the oil inlet and outlet joints must be equipped with sealing rings and fastened to prevent oil leakage.

　　12. after assembly as required, several reciprocating movements shall be carried out under low pressure to remove the gas in the cylinder.

　　II. Pollution control

　　1. the "dry assembly" method is adopted for the assembly of hydraulic parts, that is, the cleaned parts. In order to avoid the surface of parts retained by the cleaning fluid and affect the assembly quality, the assembly shall be carried out after the surface of the parts is dry.

　　2. when assembling hydraulic parts, if it is necessary to strike, it is forbidden to use iron hammer to knock, and wood hammer, rubber hammer, copper hammer and copper rod can be used.

　　3. gloves are not allowed to be worn during assembly and the installation surface shall not be wiped with fiber fabric to prevent the fiber dirt from entering the valve.

　　4. when the assembled hydraulic components are not assembled temporarily, all oil ports of them shall be blocked with plastic plugs.