How does the clamping cylinder and ejector work on this 2 platen machine?

[InjectionNoob]

As my previous post Here (http://www.injectionmoldingonline.com/forum/showthread.php?t=1350) I am trying to work out how a recently acquired 1982 Arburg 220-90-350 works so that I can 1. get to know how it works and 2. build a new control system. For a few reasons, 1 so I can know the machine inside out, 2 so I can have loads of practice in PLC programming and control systems etc and 3 obviously I'll gain a working injection moulding machine.

Anyway:

The control side of the injection unit is simple enough to control.

But I'm having difficulties understanding the clamp side.

There are in total 6 hoses, 3 smaller ones on the ejector side and 3 large ones on the clamping cylinder. 2 small hoses do advance and retract of the ejector and 2 of the large hoses do advance and retract of the clamp cylinder. Each pair goes to a directional control valve labelled respectively. The two remaining hoses, one small on the ejector side and one large on the clamp side go to the same directional control valve labelled high pressure, it's these hoses that I don't know the function of.

What do these hoses do? When should they be fed?

500
501

[JayDub]

Wouldn't they be the return hoses? I mean, if you're going to pressurize one side of a cylinder, you have to relieve the pressure on the other side, or nothing goes anywhere, right?

[ijchan223]

Wouldn't they be the return hoses? I mean, if you're going to pressurize one side of a cylinder, you have to relieve the pressure on the other side, or nothing goes anywhere, right?

because the directional valve does that already ?

found this hydraulic print from a mid 2000s machine it should be fairly similar

https://drive.google.com/file/d/1N0f97NEYQH54GL85eJys1ljgJJAF0Gsl/view

[InjectionNoob]

because the directional valve does that already ?

found this hydraulic print from a mid 2000s machine it should be fairly similar

https://drive.google.com/file/d/1N0f97NEYQH54GL85eJys1ljgJJAF0Gsl/view

Thanks for the hydraulic diagram, where did you find this? It is very similar, it would be very good if I can find the names for the components.

I have had this reply from another forum:
"The platens advance under low pressure until the mould safety is released (i.e. faces touching, nothing trapped and you haven't smashed any side cores etc). Then the high pressure is called to give whatever clamp force you have set. IIRC, Arburgs have a twin coaxial hydraulic cylinder, the smaller one giving the HP."

This makes total sense, just need to know if there is separate low and high pressure feeds to the directional cylinders as I am yet to reverse engineer the manifold.