New Chinese Press Brake
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  1. #1
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    Default New Chinese Press Brake

    Hey guys. I picked up this new to me Chinese made press brake. The story is, A guy bought it new. Didnt have a place to put it, didnt have three phase power, and after 7 years of storing it and never having it fully operational, sold it. I paid very, very little for it. Machinery is very rare and very expensive in alaska. I was thrilled even though it is typical Chinese craftsmanship. It looks to have good bones, seimens electrical components, valve body looks good, I dont see why it wouldn't work. Both motors are being reround for 240 three phase (they came 440 only) by a friend. While its apart, I am doing some quality improvements.

    Id like to add a hydraulic filter. It has a strainer, but id like to add a Spin on Hydraulic filter. Maybe like 3 or 10 Microns. Where would you suggest putting it? Return line? You can see where everything returns from the valve body. I would have to cut into the return line before it enters the valve body and weld on fitting to go into the filter base. What flow and pressure rating do you think I would need? Pump produces about 5000PSI. Below are some photos

    img_5145.jpg
    img_5351.jpg
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    img_5144.jpg

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    My 2 cents worth, leave well enough alone, stay with the factory oil strainer. Most early American press brakes used only a serviceable strainer built into the hydraulic oil tank, or a canister unit. Under normal circumstances there's generally not a lot of contamination found in a good sealed hydraulic system. The strainer is there to pick up internal contamination such as ram cylinder packing breakdown and such.

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    Really? I thought hydraulic systems were super sensitive and particles would break down tolerances. Perhaps I will just change the oil after the first 20 hours or so to try and get all the initial particles from fabrication. I guess most things like that should eventually get settle in the bottom of the tank and get collected by the magnet.

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    Hydraulic oil is non detergent, the tank should be big enough (3 minute rule)
    for dirt, water, and fines to settle out.

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    As said, it should self separate, but if you really need to put a filter in, go way oversized so you have plenty of filtering. My 230 tom press brake has a screen for larger stuff but it is not for general filtering

    Sent from my SM-G960U using Tapatalk

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    Please post more about the machine when you get it operational.

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    I will post more info when it’s operational. Right now I am shopping for new heaters as I had the motors rewound for 240v. What kinda hydraulic oil would you recommend. Shop temp stays around 60 degrees. Won’t be used in production so the oil probably won’t get super hot.

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    I'd use either AW32 (10 weight) or AW 46 (20wt).

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    Quote Originally Posted by dana gear View Post
    My 2 cents worth, leave well enough alone, stay with the factory oil strainer. Most early American press brakes used only a serviceable strainer built into the hydraulic oil tank, or a canister unit. Under normal circumstances there's generally not a lot of contamination found in a good sealed hydraulic system. The strainer is there to pick up internal contamination such as ram cylinder packing breakdown and such.
    Poor housekeeping is what I have found working on China-made machines with hydraulic components. The reservoir has been the largest source of contamination ranging from metal fines to loose casting sand.
    One look at that filter shows you have to do some cleaning in that oil tank.
    John

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    Are chinese press brakes cast iron? What about the other ones...Trumpf, MVD, Bystronic. Are not most of them cut from plate? Are they really cast iron?

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    Nothing is cast iron on this. The main frame is around 1.25” plate steel. All stick welded together the covered in bondo. From a glance it looks like cast because of the welds hidden in bondo. Actually I’ve never seen a cast iron brake. The contaminates jhruska mentioned are real though. Stick welding slag, grinding dust and gummed up old hydraulic fluid. I since scrubed out the tank and then blew out the strainer to remove the caking on it.

    From watching YouTube videos of these leaving the factory... I think they are tested first then drained before shipping. This would explain why the tank had oil residue and the lines were full of sludge as it has been sitting for years after being imported.

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    Got it working!!! I completely rewired it for the lower voltage/higher amps. Motors rewound, a ton of cleaning, new fluid. It goes up and down. Tons of kinks to still work out but the basic hydraulic functionality works and the ram goes up and down.

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    I would definitely put a large spin on filter in the return line,and not particularly fine either .In fact ,I would also put a cleanable strainer in line before the filter,such as one of the stacked plate "Cuno" filters....Ive had a fair bit of experience with Chinese hydraulics,and circulating crap is a certainty.....Its also quite likely the cylinder packings and seals will start to disintegrate and shed masses of of plastic into the oil......If a filter blocks ,it will have an internal relief,which is needed for cold oil anyway......I would also be very wary of the traces of original oil ...if its vegetable based ,it will form masses of flakes with mineral oil,and block everything.....If particles get caught in valves ,you will get faulty operation.

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    Chinese oil vegetable based? Suspect they would have eaten it If so.

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    Unfortunately a return line filter is not possible as the valve body is mounted above the tank and drains directly down into it through multiple different return "pipes" A kidney loop would be really the only option other than a pressure filter ($$$) I do have a inline suction strainer though. I m just hoping after some run time I can drain the oil, filter it or change it, and that will be good enough. It probably was vegetable oil that was used to test it at the factory and that is why it gummed up. I never thought mineral oil would gum up like that.


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