What are the characteristics of a hydraulic press?

Release time:

2023-05-12

CNC hydraulic pumps generally use internal gear pumps, while traditional hydraulic presses generally use axial piston pumps. At the same flow rate and pressure, the noise of an internal gear pump is 5 dB to 10 dB lower than that of an axial piston pump. The motor of a CNC hydraulic press runs at rated speed during pressing and return, and its noise emission is 5 dB to 10 dB lower than that of a traditional hydraulic press. When the slider descends rapidly and comes to a standstill, the speed of the servo motor is 0, so the CNC hydraulic press has essentially no noise emission. In the pressure holding stage, because the motor speed is very low, the noise of a CNC hydraulic press is generally less than 70 dB, while the noise of a traditional hydraulic press is 83 dB to 90 dB. According to tests and calculations, under general operating conditions, the noise generated by 10 servo hydraulic presses is lower than that generated by one ordinary hydraulic press of the same specifications.

Hydraulic Press

CNC hydraulic presses generate less heat, reducing cooling costs and hydraulic oil costs. The hydraulic system of a CNC hydraulic press has no overflow heat, and there is no flow when the slider is stationary, so there is no hydraulic resistance heat. The heat generation of the hydraulic system is generally 10% to 30% of that of a traditional hydraulic press. Due to the low system heat generation, most CNC hydraulic presses do not need to be equipped with a hydraulic oil cooling system; some with higher heat generation can be equipped with a low-power cooling system.

Because the pump has zero speed and low heat generation for most of the time, the oil tank of a servo-controlled hydraulic press can be smaller than that of a traditional hydraulic press, and the oil change time can be extended. Therefore, the hydraulic oil consumed by a CNC hydraulic press is generally only about 50% of that of a traditional hydraulic press. High degree of automation, good flexibility, and high precision. The pressure, speed, and position of the CNC hydraulic press are all closed-loop digital controls, with a high degree of automation and high precision. In addition, its pressure and speed can be controlled by programming to meet various technical requirements.

A hydraulic press is a machine that uses hydraulic oil as a working medium to meet different processing technologies through energy transfer. It is widely used in forging, laminating, bending, stamping, and extrusion and other related mechanical processing fields. The working cycle of a hydraulic press generally consists of rapid advance, pressurization, pressure holding, pressure relief, return, and stop.

After the pressing process and before the return process, the displacement of the main working cylinder of the hydraulic press remains unchanged. At this time, the control valve opens, releasing the high-pressure oil in the main working cylinder, which is called pressure relief. When the pressure relief process has been going on for some time, and the pressure of the working medium in the main working cylinder drops to the set value, the hydraulic press beam begins the return process under the lifting action of the return cylinder, and a large amount of oil is discharged from the main working cylinder, which is called unloading. During unloading, a large amount of hydraulic oil is released back to the tank; the main function of the pressure relief process is to release some oil that generates high pressure. Although the proportion of the liquid phase of the oil released during the pressure relief process is very small in the oil in the main cylinder, the pressure relief process is often accompanied by hydraulic shock, manifested as vibration and noise.

In order to reduce the hydraulic shock during the pressure relief process of the hydraulic press, eliminate equipment vibration and noise as much as possible, and improve the overall performance of the press, a special pressure relief circuit is often set up when designing the hydraulic system of the hydraulic press.