I really would appreciate it if someone who knows about these things could pass an opinion before I buy the wrong valve. Again
I'm making a plunger type injection molder with 2 rams, one ram closes the mold the other injects the plastic. I want to drive both off one pump.
The pump does 3.5 litres/minute and has a built in 90 bar relief valve.
The mold closing ram wants to hold at the full 90 bar while oil diverts to the injection ram.
If I bleed off less than 3.5 litres/minute the pump relief valve must dump the excess flow, thereby holding 90 bar for the mold closing ram.
I was going to control the bleed off using a needle valve, but thinking about it that doesn't work. When the injection ram meets resistance I lose my pressure drop across the needle, the flow rate drops in exact proportion and everything slows right down.
I have found a nice, cheap, pressure compensated flow regulator (throttle valve?) but when I called the manufacturers they weren't sure if I had the best solution and even more vague when it came to suggesting an alternative.
I called their distributor to get a price and they have 3 in stock, followed by 12 weeks to get more in but the girl said she'd hold one for me 'til the end of the week
The curves look good, here's the link. http://www.sterling-hydraulics.co.uk.../pdf/J02E2.pdf
Forgot to mention, on the other side of this valve is a second relief valve dumping excess flow to the low pressure return. This sets the maximum injection pressure and allows the injection ram to slow down if it must.