11 precautions for the use of hydraulic pumps

Although the structure of the hydraulic pump in the hydraulic press is very different, there are still many problems in the equipment and application.

Servo hydraulic press

(1) Precautions for hydraulic pump connection

1 The hydraulic pump of the hydraulic press can be used with bearing or flange equipment. The pump and the prime mover should be used with a base. Both the flange and the base should have satisfactory rigidity. Special attention: The plunger pump with a flow rate greater than (or equal to) 160L/min is not suitable for equipment on the tank.

2 An elastic coupling should be connected between the hydraulic pump and the output shaft of the prime mover. It is forbidden to pump the hydraulic pump on the hydraulic pump shaft or gear-driven hydraulic press. If a pulley or gear must be connected to the pump, a pair of bearings should be added to the equipment to drive the pulley or gear. The coaxiality error of the bearing and the pump shaft should not be greater than Φ0.05mm.

3 The suction pipe should be as short, straight, large and thick as possible. The suction pipe should generally be equipped with a coarse filter, whose nominal flow rate is not less than twice the pump flow rate (the filtration accuracy is generally 80-180μm). The discharge pipe of the hydraulic pump of the hydraulic press should be directly connected to the oil tank, and the back pressure of the return oil should not exceed 0.05 MPa. The suction nozzle and return nozzle of the oil pump need to be 200mm lower than the minimum oil level of the oil tank. Special attention should be paid not to accept the equipment oil filter on the suction pipeline of the plunger pump. The diameter of the stop valve on the suction pipeline should be larger than the diameter of the suction pipeline. The length of the suction pipeline should be less than 2500mm, and there should be no more than 2 pipe elbows.

4 The inlet and outlet of the hydraulic pump of the hydraulic press should be firm, and the sealing equipment should be firm. Otherwise, air suction or oil leakage will occur, affecting the function of the hydraulic pump of the hydraulic press.

5 The self-priming height of the hydraulic pump shall not exceed 500mm (or the inlet vacuum shall not exceed 0.03MPa). If an oil pump is selected, the oil pressure shall not exceed 0.5MPa. When the oil pressure exceeds 0.5MPa, the pressure seal should be replaced. Regarding the plunger pump, the self-priming method should be used as much as possible.

6 Before installing the hydraulic pump of the hydraulic press, check whether the depth of the equipment hole is greater than the shaft extension length of the pump to prevent the occurrence of the shaft-up phenomenon. Otherwise, the pump will be burned.

(2) Precautions for the operation of the hydraulic pump of the hydraulic press

1 When the hydraulic pump of each hydraulic press manufacturer is started, it should be moved several times, and the oil flow direction and sound direction are normal. After running at low pressure for 5 to 10 minutes, it will enter the normal operation state. Before the plunger pump is started, the discharge port on the housing must be connected to the pump and filled with clean working oil.

2 The viscosity of the oil changes due to the influence of temperature, and the viscosity of the oil temperature rises. Therefore, the oil temperature needs to be kept below 60°C. In order to enable the hydraulic pump of the hydraulic press to operate stably at different working temperatures, the selected fluid should have a lower oil temperature characteristic viscosity and have good chemical stability and anti-foaming function. It is recommended to use L-HM32 or L-HM46 (GB11118.1-94) anti-wear hydraulic oil.

3 The fluid must be clean and must not be mixed with mechanical impurities and corrosive substances. Hydraulic systems without filtering equipment on the suction line must be refueled through an oil filter (less than 25μm).

4 The maximum pressure and maximum speed of the hydraulic pump of the hydraulic press refer to the peak values allowed in the application in a short period of time, and should be prevented from being used for a long time, otherwise it will affect the service life of the hydraulic pump of the hydraulic press.

5 The normal working oil temperature of the hydraulic pump of the hydraulic press is 15~65℃. The maximum temperature on the pump housing is generally 10~20°C higher than the oil temperature at the pump inlet in the oil tank. When the oil temperature in the oil tank reaches 65°C, the maximum temperature of the pump housing does not exceed 75 to 85°C.

Jigsaw four-column hydraulic press