Planning a bender/press brake

[mike os]

Planning a "press" bender, usual DIY H frame arrangement with hydraulic power/jack

Would like to bend up to 900 wide and 3mm thick stainless, usually only 16-18g & narrower & MS, occasionally much heavier MS... 10x70-10x100 ( optional at this end I can always get them done, but waiting is getting to be a pain in the ass)

what kind of tonnage do I need to form bends?

We can worry about structural strenght later it will be plenty strong

probably try to add guilotine & punch press too, if your going to do it might as well make it as hard as possible ( & mind your comments Sparkley)

 

[madkayaker]

perhaps consider how big a bottle jack have you got. Industrial presses i have seen have been about 6-10 ton

 

[mike os]

Will buy new so anything goes...20-50ton not a problem

but no point going too OTT & risk killing it for occasional use at high capacity.

so thoughts on say 30 ton? too much? reasonable? stupid?

 

[madkayaker]

30 will bend most things i say if you have a strong frame

 

[aametalmaster]

I just finished one and would go with a 30T jack. I started mine 15 years ago and would change a few things as far as frame thickness but its fine for what i am doing with it...Bob
http://www.mig-welding.co.uk/forum/showthread.php?t=19649

 

[mike os]

thats my thoughts, should punch 10mm in 6mm plate too I would think.

frame wise:-

100-150mm chanel section or 100 box?

dont like box for the "bending" ( top rail & Table) parts as it cant be reinforced internally..... easily anyway.

personally I like the idea of chanel section with web reinforcement between holes ( 1 in 3?) for uprights,

chanel table, 2 pieces back to back with angle/chanel ties and face reinforcement in the web round the holes iinto the legs, possibly 3x web reinforcement too.,

top as above but welded to uprights & possibly triangulated above load point, possibly with 25-30mm plate as below.

tool carriers 25x150 -30x180 plate top & wide enough to fully span both chanels on the table, tooling between bolted stops/clamps.


sound like it works? OTT? where can I save ££ where do I need to beef it up?

 

[Paul.]

Force required for bending will depend on the tooling, without getting too involved in theory, a rule of thumb is to select a vee width of 6 to 8 times the plate thickness, so say 3mm steel plate bent on a 25mm vee will need a typical force of 24 tonnes per metre, the wider the vee the less force required but the bend radius will increase, for stainless steel multiply the force required by about 1.5, for aluminium multiply by 0.5

I once made a portable press for bending 3mm aluminium sheet on site (cold store refurbishment contract), 1250mm capacity powered by a couple of 20 tonne lorry jacks, quite slow but better than running back to the shop just for a simple bend.
This chart may help you choose a suitable jack and tooling

 

[Hitch]

Paul has beat me too it with that chart...them tonnages will be per metre, in mild steel.

For stainless, youll be looking at about x1.5 those figures.


Have a look at some pictures of pressbrakes, think 25mm plate for them kind of forces....

 

[mike os]

Excellent chart guys, thanks

plan is for larger ( or all) section to be "air bent"... dont usually need tight radius, & when I do I can always get it done on a proper machine, its just the inconvenience of bothering busy guys to either do it or let me on a machine for the usual £20 jobs, waiting a week or having to go back 2-3x to get things sorted/adjusted... you know the score

reading the chart as most of what i seem to use is 1.5mm st/st or ms at most...30t is enough? ( I can always uprate the power, its the frame that needs to be right)(3mm st/st on a 32mm vee =29ton?)

its only the occasional full width too, more of a convenience than a serious workhorse

tooling will be 88deg V mainly I guess?

HItch.... which parts 25mm? ( been looking at loads... now need to formulate my own, I hate straight copys, no fun at all LOL)

 

[Paul.]

800mm of 1.5 stainless, air bent on a 12mm vee, about 24.5 tonnes, so in theory 30 tonnes should be ok, the one I made would bend most stuff on 1 jack in the middle of the beam,
Tooling was standard eurotooling borrowed off the press in the shop. we made a flattening tool for it as well, for doing safe edges.

 

[Hitch]

Yes, youve got the idea of the chart. Vees over about 12xt, start to make the folds look untidy imo.

Ideally, youd be working 6xt<3, but as above, the biger the vee, the less force required.


The top and bottom will deflect, not so much of an issue on a narrow machine i guess, and repetitive accuracy isnt a big deal to you i suppose?

 

[mike os]

ty guys

hitch:-not espescially but I am a bit anal about quality so needs to look right

plan is for something like 25-30 x 200 x 900 vertically, one under the die & one as a toolholder, depending on what I can scrounge.... may be 2 x 15mm or similar below edge & plug welded together

A I can get access to machining facilities I will probably make/modify tooloing to work ( no nasty hse spankers about in a home 'shop)

if I can find a cheap 50t I may use it anyway... end of the day I dont think this will cost more than £200 or so to make/modify if it goes wrong

not a thing you usually even think about when you have a proper press available..

 

[madkayaker]

cheep 50T jack http://cgi.ebay.co.uk/Toolzone-50-T..._Lifting_Moving_Equipment&hash=item414f9af8d5

 

[mike os]

Well Ive made a start

Frame ready for fitting out, bed & toolholder ready for working on & jack in the 'shop ready for me to get some mounting plates made

Somehow I cant see me having flexing issues... table & blade are 35mm

All I could get second hand... or 6-10mm
All second hand/ left over steel so far...total costs £155