Thanks for all the response.The spring I mentioned made from disc springs is some disc springs stacked in series,then put the stacked column into spring house.The vendor said this spring can provide a shoter length for installation,and they are popular used in some power plants and chemical plants.
Dear sun wee,the vendor's website is in Chinese,and the information is very limited.I think it make no sense.
It's my first time to meet this type spring,I am not sure it's really as better as what vendor said.Any concerns and suggestions will be appreciated!