50 TON PRESS BRAKE MODIFICATION 4

[CoolContractor]

I am going to modify my Harbor Freight 50 ton press brake and need some advice. The upper C channel is 7” tall, 2 5/8” deep and 1/4” thick. The lower C channel is 7” tall, 2 5/8” deep and 3/8” thick. Both C channels are 35” to the support pins/ mounting bolts. I would like to widen the working opening from 32” to 52”. How do you calculate the new C channel size for the added span? Looking at the picture of the press, I would like to attach the existing upper C channel that houses the hydraulic ram to the new C channel as to not have to cut out all of the factory welds. If you have any questions regarding measurements and specs, please ask me.

 

[3DDave]

There are too many options to give a good answer.

How are you planning to attach the new C-Channel to the existing one?

 

[CoolContractor]

I was considering doing this.

 

[chicopee]

With the newer channels that appear to have the same depth as the existing ones, the end moments will be greater and consequently the end bolted connections will be under greater shear forces from the end moments and from the vertical loads if you keep the rating at 50 tons. I would have new channels with greater depth to reduce the shear on the end bolts and either weld the entire length of the existing channels to the new channels or just get rid of the existing channels depending on what the math tells. You also have to recalculate deflection of the improvised press. The uprights will experience greater deflection, therefore they'll need to be reinforced and I would reinforce the bolt holes due to the increase shear loads. By the time you are done it may be cheaper to buy a new press.

 

[chicopee]

Another option is to buy the stock and make your own revised frame, then scavenge the equipment from the existing press. I have seen similar situations.

 

[tbuelna]

Maintaining alignment between the hydraulic cylinder and the component being pressed is a major consideration. 50 tons is a huge amount of force, and if your press frame deforms when applying that amount of force to install a part it can easily cause serious damage.

 

[MikeHalloran]

Just to avoid future confusion, the object you are proposing to modify is a forcing press.
A press brake is a different tool, intended for a different job.


Mike Halloran
Pembroke Pines, FL, USA

 

[CoolContractor]

I am planning to use the press to brake aluminum sheet.

 

[CoolContractor]

What would be the approx. tonnage needed to brake 48" of .090 5052 aluminum?

 

[Nescius]

The force needed could vary greatly. Online calculators are available through a google search. Key factors are the desired radius of the bend and the die geometry to produce that radius.

I could "brake" a 48" wide sheet of .090" aluminum with my bare hands...to a very large radius. Sharper radius = more force, maybe a very large force, depending on what you want to do.

I'm guessing you're planning to use some sort of simple stand-alone brake tooling with the press. Getting a sharp, 48" long, uniform bend with pressure applied to the tooling at a single, central point will require a VERY stiff tool. Look at the construction of factory-built bending equipment for a reality check on this point.

 

[chicopee]

While 50 tons may not be required for bending Al sheets, you should still modify the existing press to 50 ton capacity. I also think that a press brake would be suitable for the job as you can vary the width of Al sheets without significant modification.

 

[IFRs]

The tonnage also changes if you are using an air-bending or bottoming die, and slightly if you are bending with the grain or against the grain. The Aluminum Association has recommended bend radii for various alloys and grades of aluminum. For 0.090 AL5052 H-32 ( a common hardness ) the minimum bend radius is between 1 and 1.5 times the thickness for 90 degree air bends. At 48" long, you won't much tonnage at all, I'd venture a guess at maybe 2-3 tons.

 

[CoolContractor]

I guess it's a good thing I got a 50 ton press! I really want to bend 42" to 48" wide aluminum for windshield frames but my press opening is only 32". From the other people who posted comments, I will have to rebuild the entire press to accomplish this. I do appreciate all of the input. This is a very good site. I'm glad I joined.

 

[Nescius]

2 or 3 tons seems far too low. That's only 83-125 pounds per inch of width. Plug some numbers into one of the online calculators, or do a google search for "air bending tonnage chart".

 

[MikeHalloran]

CoolCon, you are still proposing to use the wrong tool for the job, so don't invest more money in making it a larger, but still wrong, tool.

Go to a used machinery dealer and ask them to find you a used 48" press brake.
That's actually pretty small for a press brake; they may have larger ones ready to go.



Mike Halloran
Pembroke Pines, FL, USA

 

[ornerynorsk]

A hand brake might be a much better option.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[CoolContractor]

Hi Mike, thanks for the input. I have been using a friend's big brake to make my 90° bends but I need to make radius bends using a 1" round bar as the punch. I tried to use a Baileigh electromagnetic brake to bend the radius like they do on YouTube. It works with steel but not with the aluminum I want to bend. I am open for suggestions.

 

[dvd]

How many of these frames are you going to use? Go to a sheet metal fabricator and get them done. Spend your time on the part that is going to make you money. I agree with the comments about the inappropriateness of converting the press. It has no gibs, it has a center cylinder, it is going to take your time to convert it - spend that time on the part that is going to make you money.

 

[tbuelna]

Here's a link to a press brake tonnage calculator. As others noted, for small quantities you would be better off contracting the work to a fabricator with the proper equipment. Of course, the proper brake die set might be fairly expensive, but it looks like a .50" radius tool is available as standard.

Alignment of the die set is important. I don't think this DIY hydraulic press brake produced very good results.