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Di-Acro 14-72 Press Brake Not Flat? Bent Parts Have Uneven Bends in Center of Length

Econdron

Hot Rolled
Joined
May 31, 2013
Location
Illinois
I just purchased a used Di-Acro 14-72, 35 ton press brake. I'm very new to press brakes, this is my first time even using a press brake. I'm bending 18ga sheet at 50" long using a 3/8" V-Die, bending a 1" flange. I dialed in the machine so I'm getting a 90 degree bend, which is 90 on both length ends of the flange, but in the center, it's under bent by a couple degrees. Upon inspection, when I jog the machine down, I can see a very slight visible gap between the dies in the center when the ends of the dies are lined up. I replaced the top die, no change, replaced the lower die, no change. Granted all the tooling is used and came with the machine, but I don't think it's the tooling. As far as I can see, the machine has no adjustment for leveling the die.

Is there a common wear point on these machines that occasionally needs to be re-machined or replaced? Or is it somewhat common practice to use shims to level the tooling?
 

Bondo

Hot Rolled
Joined
May 14, 2011
Location
Bridgeton NJ
Yup, very common issue. I use brass shims as they don't really stick to the dies when flipping them. My primary bottom die is a 4 way die
 

gbent

Diamond
Joined
Mar 14, 2005
Location
Kansas
That is less than 1/2 capacity, deflection shouldn't be a problem. You can measure the dies to see if they are worn, you can also remove the dies, close the brake, and check for uniformity of gap. You can then shim as necessary.
 

Garwood

Diamond
Joined
Oct 10, 2009
Location
Oregon
One real quick way to asses an old press brake is to look at the paint on the ram. If the paint in the middle shows evidence of cracking and chipping off while the paint towards the edges is better, you got a good chance that brake's had a real hard life.

On a brake that size/lightness it wouldn't be a big deal to pull the ram and mill it flat if it's deformed past the point of light shimming. I mean if you're having to put 50 thou of shim in a 72" machine or thereabouts it would be best to machine it straight again or you'll just destroy longer tooling.

Another thing- Those Diacros are real easy to turn up the pressure on. You might check max pressure and maybe even a wide test bend over capacity and see what it does. If it does it no problem then you know why it's bent.

A friend has a 75 ton 96" Diacro that has been run at 125 ton 120" for the past 25 years. It does it, but you gotta be careful with short parts. I did some tight radius 1/2" parts in it and didn't know it was already way over capacity. Things were squealing, but she did it.
 
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Fish On

Hot Rolled
Joined
Feb 23, 2014
Location
Mobile, Alabama
If he's got daylight in the middle only when jogging the machine down, it's not a crowning issue, that machine is sprung. One of the most important figures to remember on a press brake (and probably the most frequently ignored) is 100% of tonnage on no less than 60% of the bed. That figure more or less gets you the max tonnage per foot, if the machine doesn't have a specific rating for such.

That means no 1' piece of 1/4" on a 35 ton machine, even though it has more than enough tonnage.

Cheap solution: shim
Correct solution: get the bed and ram milled flat.
 

TKassoc

Cast Iron
Joined
Aug 19, 2009
Location
Oakland, CA
I had this company re-machine the bed on a 12' press brake 20 years ago before I installed a Wila crowning bed--> https://www.brakemill.com/ It will probably cost more than your machine is worth to fix it. A cruder but much less expensive fix it to have someone like Perfection--> https://www.pmtw.com/product-details/die-rails/ make you a die rail with some crown build in...nowhere near perfect but a reasonable compromise. If your machine has a die rail already you can ship it to them for reconditioning and they can add crown when they clean it up.
 








 
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