HYDAC’s OXiStop technology reduces tank size by more than 50 percent, enabling a complete hydraulic power unit (HPU) design to be located on a press’s maintenance stage.
THE CHALLENGE
A company specialising in the production of high-quality electrical sheets and packages approached HYDAC to assist it reduce the maintenance stage of a hydraulic press footprint so that a HPU and operation and maintenance activities could be accommodated, according to HYDAC Systems and Services Manager Harald Cremer.
Other project challenges included reducing carbon dioxide footprint via a compact design and oil volume as well as usage of a modular concept with as many non-variable parts as possible for a complete series.
“The main challenge here was to make the unit as compact as possible,” Mr Cremer comments.
“But it was not specific to the OXiStop system – it was connected to the surroundings and requirement for human intervention.”
Footprint challenges common
Mr Cremer points out that these specific “footprint” challenges are common to many companies.
“Hydraulic tanks are very large because the presses they operate are very dynamic. Therefore, a large reservoir that can deaerate oil is required.”
The project manager, Pascal Koebrich, explains that HYDAC's OXiStop is a tank solution for hydraulic systems that integrates the hydraulically driven degassing unit that continuously eliminates free and dissolved air from the hydraulic oil.
“The OXiStop system is best suited for applications with small pendulum volume combined with very high pump flow rates that usually still lead to huge tank sizes because of the needed degassing,” he says.
“The OXiStop system continuously eliminates free and dissolved air from the hydraulic oil. Therefore, a big tank is not required for degassing, which is basically what the OXiStop is all about.”
THE SOLUTION
HYDAC reduced tank and oil volume with its specially developed and patented OXiStop system.
The solution can revolutionise conventional design by reducing volume by a ratio of up to 1:10.
Other advantages to the customer, besides a smaller tank, include:
*Resource preservation by using smaller amounts of oil with longer lifetimes
*Higher process velocities due to better fill grades of pumps and avoidance of cavitation
*Avoidance of ambient contamination by a membrane (airtight package)
*Higher system cleanliness by preventing deposits in the tank and hot surfaces, continuous degassing, and effective filtration
A really good solution
“It’s a really good solution,” Mr Koebrich emphasises. “The OXiStop here was a type of plug-and-play.
“Our designers even had to make the tank a little bigger to accommodate all the connections required – the main return line, various suction lines, and additional auxiliary return lines.
“So, if there hadn’t been so many connections, we could have even reduced the size a bit more!”
He highlights that also impressive is the tank size of 500L, which is driven by a 1200L/min pump.
“Keep in mind we usually calculate four times the pump volume. That means that with approximately 1000L/min you could have a tank size of 4000L, and we ended up with a tank size of 500L.”
Issues along the way
The dynamics of the hydraulic system was the first challenge in terms of defining the correct valve sizes to have the least pressure drop, Mr Cremer points out.
Mr Koebrich explains that many issues centred around correct sizing of orifices because “small changes have big impacts”.
“The entire HPU was tested at HYDAC’s test bench, with tests on the test bench executed in collaboration with the customer,” he adds.
“We couldn’t do the test in combination with the press at our facilities. That was done at the customer’s location.
“And to this day, there are modifications and updates that the customer would like to implement even after we’ve built 10 systems. It is a continuous improvement process in close collaboration with the customer.”
Testing software geared to real operating conditions
HYDAC’s engineering team made use of testing software, which specifies several steps as defined by the customer, to get as close as possible to real operating conditions.
THE RESULT
Using OXiStop technology reduced the tank size by more than half, resulting in the complete HPU design weighing less with smaller dimensions.
OEMs and end users benefit from the HPU being located on top of the press at the maintenance stage.
“We started working on this project in 2015 and we delivered the first system in 2017, with almost two years of engineering dedicated to completing the system,” Mr Koebrich concludes.
For further information on HYDAC’s OXiStop tank solution, visit: https://www.hydac.com.au/oxistop.html
To contact HYDAC Australia, visit hydac.com.au or call 1300 449 322.
