Brake Press - Angle of the Bend

Yeah, a classical question.

In my oppinion you're just right. You must build the die wrong (bent to the other side) to end up with straight parts. Just this simple, this is the way I like things to be...

the press will have adjustment screws so you can adjust the bend to compensate for this problem. look in some of these searches.

http://www.google.ca/search?hl=en&q=%22press+brake%22+%2Balignment&btnG=Google+Search&meta=

there is a specified bend allowence and corner radius for the thickness and degree of bend i am sure you have this info if not you can email me at kross111968@aol.com and i will get it to you. depending on the length of the bend and the mating straightness of both the top and bottom tools it could simply be a matter of flex and to determine this you will need to step the upper tool down and check the entire span with feeler gages to determine complete suface mating within 2.5 % of the material thinkness

Very common problem. Most breaks do not have adjustable camber to compensate for this. Cambering would fix this yes but it would only make sense if you were mass producing certain parts. A simple solution on a per peace basis is to over-bend the peace to 2-3 degrees past then bump it back to the desired bend. Iv done this myself on many occasions, It works. Whether or not it is feasible for your situation is up to you.

Remove all tooling from the press and lower the moving portion to the bed or anvil. Look for early contact or gaps. If the stroke doesn't allow this much travel, measure the distance between the top and bottom, looking for the area that shows the largest gap.

If the gap is consistant all the way across, then start checking the tools for wear in their centers. Many people make the mistake of doing all their bending in the center of the press, wearing the tools in the center prematurely.

The last possibility that comes to mind is that the moving half has been warped out of line and is not coming down on the centerline. This could also be in the tooling if you use segmented tools as opposed to full length (contiguous) tools.

Check all mounting surfaces for material build-up that could affect the mounting position of your tools. Small changes when extrapolated make big differences.

You did not say what make of press brake you are using.

You can buy a top punch holder that has taper setting pieces to correct the camber of the top beam, refer to the Elga type punch holder.

If your machine does not cater for this and your beams have not been damaged( if the gap between them is constant) and the tooling is not worn then I would suggest you use a bigger 'V' opening to reduce the force to do the bend.

If that still does not work I suggest that you try to shim either of the tools, the punch or the V-block to correct.

When you shim do not exceed a force of 100 ton per foot of tool. If you make use of gooseneck tooling reduce this even more to not damage the tool.

Setting the depth and the speed of the bend is hard. The bed of the die must be level across the whole machine. Setting the depth take a lot of time for each machine will respond differently to each setting I have found.

The thickness of the metal will also limit your depth.