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Author Topic: Sheet MEtal Bending with Mach3  (Read 9763 times)

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Sheet MEtal Bending with Mach3
« on: January 18, 2010, 01:53:59 AM »
I wish to control A Sheet Metal Bending press with Mach3 by Single axis control of the Back Gage. Has any one customised Mach for this kind of applications? Back gage is a platform behind the front of the press from where sheet is fed over the shaping die and back gage is positioned at different locations for referencing the plate to be bent.

Thanks and Rfegards.
Mahesh Vyas.

Online Tweakie.CNC

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Re: Sheet MEtal Bending with Mach3
« Reply #1 on: January 18, 2010, 02:57:12 AM »
Hi Mahesh,

Sounds like a very interesting application which, I think, Mach3 could handle with ease - it would work just as well controlling one axis as it does controlling six. Good fortune with your project.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Sheet MEtal Bending with Mach3
« Reply #2 on: January 18, 2010, 04:18:41 AM »
Dear Tweaky,
Thanks for your encouragement. I still wonder that this area must not be unexplored with Mach... Just waiting for the veterans to chirp in..

Mahesh Vyas

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Re: Sheet MEtal Bending with Mach3
« Reply #3 on: January 18, 2010, 04:37:03 AM »
There is a guy that has done pipe bending with Mach, not the same but similar I suppose? Have a search for it in the Show and Tell section.
Hood

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Re: Sheet MEtal Bending with Mach3
« Reply #4 on: January 18, 2010, 04:38:17 AM »

Offline Dan13

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Re: Sheet MEtal Bending with Mach3
« Reply #5 on: January 18, 2010, 11:09:59 AM »
Sheet metal bending is not like pipe bending. With pipe bending you control the length you want to bend with one axis - pushing the pipe, and then control the bending angle with another axis - a rotating one - a pin rotating around a pivot pin and bends the wire in between. If it is a 3D bender then there will be a third axis as well, that either rotates the wire or the bending mechanism around the wire.

In sheet metal bending you usually "feed" the sheet metal manually against a stop which can be CNC controlled. Once in position you push a pedal and a press comes down with a formed tool and bends the sheet metal against a die at the bottom - underneath the sheet metal. You can't control the bend angle with this. If you need a different angle, which is very rare (all the bends usually 90 degrees) you'd use a suitable die and tool. Thus, with a sheet bender you only control one axis and only in single block mode.

Daniel
Re: Sheet MEtal Bending with Mach3
« Reply #6 on: January 18, 2010, 12:34:27 PM »

You can't control the bend angle with this. If you need a different angle, which is very rare (all the bends usually 90 degrees) you'd use a suitable die and tool. Thus, with a sheet bender you only control one axis and only in single block mode.


That's not true at all.  Working in a sheet metal shop I see dozens of unique parts, and I can tell you that all the bends are NOT 90 degrees.  Furthermore you have direct control of the angle of the bend by the distance the press ram travels.  Also factoring into this are the die opening and punch radius.  You can even use an accute 88 degree bottom and a narrow punch to over bend when in metals where springback is an issue.  Bottoming the dies out to bend the exact angle required is actually rarely done as it takes more tonnage for a given bend and it is actually more difficult to control the resultant angle.  Research "air bending" for further details. 
Current tech press brakes have 5 or more axis of motion in the flying back gauges, and can be programmed to do multiple bends across a part.  Mach 3 would make a great front end to a system like this, or even just a single axis back gauge. 

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Re: Sheet MEtal Bending with Mach3
« Reply #7 on: January 18, 2010, 12:37:50 PM »
if you want use the X axis for your stop, and on the stop "finger(s) or Plate", put a limit switch that when the sheet is all the way back, the one or two switches are your confimation that the sheet is fully against the rear stops as a check.

further, if you want to control bend angle, AND you do have on/off control of the press hydraulics (should be a soliniod), you can make a data wizard, that can take into account the thickness of your metal, (bending tool type if neccessary), and how much to push (with a spring back adjustment), for set angles.

scott
Commercial Mach3 & Mach 4, Design/Build/Retrofit CNC and Industrial machines.
http://www.ss-systems-llc.com/

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Re: Sheet MEtal Bending with Mach3
« Reply #8 on: January 18, 2010, 01:23:14 PM »
Koko,

Thanks, I didn't know about the modern 5 axis benders. Those we were working with had only one axis and control of the bend angle by means of the amount of lowering the press, although possible, wasn't used much because of the trial and error involved in acquiring the desired angle - we didn't have control of the press position, it was just a hydraulic press.

And I didn't mean ALL the bends are always 90 degrees. Said that USUALLY they all tend to be 90 degree. More than 90% of what we were doing were 90 degrees bends.

Daniel

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Re: Sheet MEtal Bending with Mach3
« Reply #9 on: January 18, 2010, 03:03:56 PM »
Most Press Brakes ive seen have a mechanical stop for the hydraulic piston, not a limit switch. This stop is moved by a motor and the position is read on a dial. So bending a 90deg in 1/4" the stop would be set differently than a 45deg. Hydraulic presure would be the same.
Ryan