Problem of hydraulic directional control valve continued after changing 3 factor

One morning last month, Antonio emailed us that there was a problem with AAK hydraulic directional control valves purchased some time ago, and a problem was found in the factory commissioning of the bending machine. The starting pressure of the hydraulic system of the bending machine will suddenly increase. Their engineers think it is caused by the instability of the hydraulic direction control valves and ask us to replace it. I'm totally confused. Because this hydraulic directional control valve is produced and inspected in full accordance with the parameters provided by Antonio, and the parameters of the hydraulic directional control valve are approved in the commissioning stage of the bending machine.

Antonio is from Prada Nargesa company in Spain. He has cooperated with AAK on hydraulic directional control valves for several years. This is the first complaint from him. In the sample stage, Antonio informed that this hydraulic direction control valve was used in the hydraulic system of the bending machine produced by his company. It was noted that the bending tonnage was required to be 400 tons, the maximum bending length was 6 meters, and the bending accuracy was +/- 0.3°. The pressure and accuracy requirements of the hydraulic direction control valve were very high. After our internal discussion, we found the problem strange.

AAK engineer asked Antonio to send a video of the working condition of the hydraulic system of the bending machine for us to check what the problem is. Through the video, we found that there was a problem about the installation position of the needle valve of the integrated valve block of the hydraulic system and the position of the hydraulic directional control valve. It was preliminarily judged that the pressure regulation mode of the hydraulic system of the bending machine is not correctly designed, and this hidden danger will come out after more than 8 hours of continuous test run. But the designers of their company didn't agree with our proposal and thought we were shifting the responsibility.

I suggest Antonio give us 30 days to redesign the integrated valve block. If there are still problems after installation, AAK is willing to bear all costs. Considering that these bending machines are in a hurry to ship, it will take longer time if purchasing new hydraulic directional control valves, moreover it is not guaranteed that the new hydraulic directional control valves will be no problem, Antonio reluctantly agreed with AAK proposal. After 25 days, AAK sent out the integrated valve block with hydraulic directional control valve, which was installed and debugged for more than 8 hours. Everything of the bending machine was normal, and their designers had to affirm it.

AAK professional engineers designed the pressure regulation of the hydraulic system of the bending machine as a modular type, and rearranged the position of the needle valve and the hydraulic direction control valve, so as to provide the proportional regulation function. At the same time, the unloading circuit is simple and reliable.