Sheet Metal Bending Material Diameter and Feed Data Calculation

[QandATime123]

Hello All,

I'm currently working on some PLC programming for a metal bending machine that uses two cylindrical spindles (one on the top and one on the bottom) that use a motor to rotate back and forth and rotate a rectangular piece of metal that is fed between them. A clamp attached to a linear actuator feeds the sheet metal between the cylinders.

Problem 1: In some parts of the code, the original programmer asks the user to input material diameter. I scoured the internet to find information on this, but most of the info was relevant to tube bending. Diameter implies that a tube of some kind is involved, but when I visited the facility, they were using flat sheets of metal. I thought about the outer diameter of the roll of metal that was fed into the machine, but if that was the case, the material diameter would decrease as more metal was used and it would not make sense in the code. A flat sheet of metal has an infinite radius, so could the material diameter be adjusted for thickness? I'm out of ideas guys and I really need some insight and reference information if possible, so I can read about it myself.

Problem 2 Background (check the paragraph beneath this for the problem regarding this function): The code uses a counter that tells the logic controller that one bend has been completed before the feed clamp feeds the metal between the top and bottom cylinders for the next bend. What happens is that the feed length input by the user is fed to the PLC. The PLC uses a sensor that measures the distance the feed clamp moved after it is retracted back to its home position. A comparison block in the PLC checks the sensor value and compares it with the Feed Data input from the user. When the sensor value reaches the Feed Data value or surpasses it, the PLC commands the feed clamp to stop and the material clamp fixes the metal in place so it can be bent.

Problem 2: Following each bend, the Feed_Data value is reset by the PLC to be the feed length of the first input minus the top cylinder bend angle of the last input (there are 6 groups of inputs on the touch screen and each one contains the variables, Feed Length, Bend Angle, and number of repeats. The PLC alternates between the top cylinder and bottom cylinder to bend the metal. The user chooses which cylinder they want to start with).

Problem 3: Could someone please explain what is the calculated top/bottom spindle setting and why is it important? How is this calculation justified? Could anyone please offer some insight? (In the program, the spindle setting is calculated by taking the sum of the spindle radius and material radius. It seems to be half the shortest distance between the center of the spindle and the outer surface of the other spindle. I did not see a distance changing mechanism when I looked at the machine but I think I missed something.)

Problem 4: The total tool setting reading is calculated by subtracted the total offset from 2000. The total offset is calculated by adding the top spindle radius, bottom spindle radius, and the entire material diameter. Could someone please explain why a fixed number like 2000 would be used and how the total offset is useful to the technician, since it does not seem to be used by the machine?

(the PLC calculates length by making each unit of length equal 0.01 inches so 2000 is the same as 20 inches. The machine interprets analog values on an integer scale from 0 to 24678)


Please note that the material radius, and spindle radii are not used by the machine, but they do show up on the interface. I don't understand why those values are not important to the machine. Does it mean that those values need to be adjusted manually?

I understand that this thread is a bit lengthy, but I would like to thank you in advance for any comments or insight you can spare.

Best,
QandATime123


I have added a drawing of the machine below. I could not find something similar online, so I drew it myself and labeled it. Please let me know if you need more information.

 

[MikeHalloran]

Maybe a photo or diagram of a similar machine would help us.


Mike Halloran
Pembroke Pines, FL, USA

 

[QandATime123]

I have added the attachment here as well. I was not seeing it in the post above.

 

[MikeHalloran]

A diameter would be a logical input for a tube mill, which would include an uncoiler, a straightener, some sort of continuous traction drive, a set of rolls that gradually form a moving strip into a tube, a continuous seam welder or some sort of mechanical seamer, and a flying cutoff shear to cut the tube into programmed lengths. Sort of like the machine that makes continuous drainage gutters, but a little more complicated.

Your sketch shows a primitive uncoiler, that lacks the usual straightening rolls, unless those are what you are attempting to depict in the upper part of the sketch.
The sketch includes no sort of bending mechanism.

From your initial text, I thought perhaps you were talking about some sort of coiled stock to pierced and folded panel converter, as might be used in a white goods factory to make the exterior panels of refrigerators, washing machines and such from prefinished coil.

I think you need to make another visit to whatever machine you are writing code for, take a lot of photos, and come to a better understanding of exactly what the machine is intended to do.



Mike Halloran
Pembroke Pines, FL, USA

 

[robyengIT]

what about this (video clip attached)?
steel sheet thickness : 1.5 mm to 3.5 mm
steel sheet width : 800 - 1000 - 1250 - 1500 mm
production speed : (ruled by welding speed) - always 1500 mm/min for any diameter

 

[berkshire]

That's a spiral pipe machine. I don't think that is quite what the OP is trying to describe.
B.E.

You are judged not by what you know, but by what you can do.

 

[QandATime123]

Hello All,

I have seen the machine in action. The metal is fed between the cylinders, which are located close to each other but one is attached to the upper disc and the other is attached to the lower disc. Each disc contains an axle connected to a motor, which rotates the disc clockwise or counter clockwise while the other cylinder is fixed. Then, they alternate in the next bend. Please let me know if you need more information to answer my questions above. I really appreciate it guys!

Best,
QandATime123

 

[QandATime123]

Could anyone please lend a hand?????? I've tried 3 forums so far and not one answered my questions directly. I'm trying my best here....

 

[MikeHalloran]

I am sorry, my Vulcan Mind Meld Machine is the The Shop.

I cannot see what you saw.

I cannot make sense of your questions, or your responses to queries, given my inability to form a mental image of the machine you saw. My best guess is that you did not see it well enough, or close enough, or long enough, to understand how it works, or how it is intended to work, for purposes of controlling its motions.

I can understand if you can't give away the store by providing photos or videos in order to elucidate your point, but without some better images and/or better word pictures, nobody here, or anywhere else, will be able to help you with the challenge you face.





Mike Halloran
Pembroke Pines, FL, USA

 

[3DDave]

Is there a picture of what the machine is supposed to produce?

I looked at the diagram but it is unclear because it looks like the sheet metal goes through the cylinders but is not changed. I know this isn't the case, but not knowing what happens to the metal makes it hard to understand the controls for that change.

I think you must have changed the perspective between different areas of the machine to try to show details, but this lost the relationship between different areas of the machine.

 

[berkshire]

There are some sheet metal bending machines that use a cut away cylinder as part of the bending mechanism. the part is clamped then a half cylinder rotates in a confined bearing to provide the bending action . Do you have one of these machines . Pictures / Photos will be much better.
B.E.

You are judged not by what you know, but by what you can do.

 

[QandATime123]

Alright guys. I'll try to describe the machine as thoroughly as possible:

Imagine a cylinder attached to the edge of a small disc. When the disc rotates, the cylinder rotates along the circumference of the disc. Now place another disc underneath it with another cylinder, but the cylinders are facing opposite sides. When the metal moves between the cylinders, a material clamp holds a thin rectangular metal sheet in place. When one cylinder turns, the other cylinder does not move. When this happens, one cylinder is bending the metal around another cylinder. The machine stops rotating one of the cylinders when the sensor of a motor picks up the desired angle specified by the user. Then, that cylinder rotates back to its home position and the bottom cylinder bends the metal in the opposite direction while the top cylinder is fixed in place.

If you imagine the two cylinders being in the front of the machine, the back of the machine contains a conveyor belt that is attached to a moving clamp. When the clamp is in its home position or sitting at the back of the machine, it clamps the metal and pulls the metal from roller, in effect, feeding it between the cylinders. When the sensor picks up a distance that is equal to the distance defined from the user with respect to home position, it stops, releases the metal, and moves back to home position. The material clamp is located closest to the cylinders and clamps the metal, giving the feed clamp time to move back to its home position.

Please let me know if this is enough.

Thank you! =)

 

[berkshire]

Your description to me is some kind of automated rolling machine . Not what I would describe as a bending or folding machine. what is the smallest radius this machine can produce?
B.E.

You are judged not by what you know, but by what you can do.

 

[MikeHalloran]

Given that you start with a coil, where does the rectangular sheet come from?

Mike Halloran
Pembroke Pines, FL, USA

 

[3DDave]

Apparently the machine is not documented. The typical first step is contact the originator - either the company or the guy who programmed it. If that is not an option, the only solution is to recreate that documentation by determining what the user expects the machine to produce and what inputs and materials they expect to supply and then experimenting with the interface and the PLC code.

I guess the machine is much like a channel letter bender, as described here

https://www.youtube.com/watch?v=-xc-9gF4bIQ

 

[berkshire]

3D Dave
The machine in your movie seems to operate on the principle I described, that is essentially an up / down folder with a bump feature. although it seems to also have a Vee groover. Now if we could just get the OP to get some photos we could see what we are really dealing with.
B.E.

You are judged not by what you know, but by what you can do.

 

[QandATime123]

Sorry it has taken a while to respond. The machine is custom made for making heating coils. It has no precedent. I tried contacting the original company that produced it, but they got rid of the documentation from 20 years ago, so I have to pick up the pieces. I'll try to take a picture of it, but since the machine is one of a kind, I'm not sure they will let me. If you have any insight in the meantime, please let me know. =)

 

[QandATime123]

Also, the rectangular sheet is already produced somewhere else and its sent to the shop for bending. Its thin steel and its somewhat flimsy, so you can roll it. I think the material radius is referring to thickness.

 

[berkshire]

So is the machine a tube bender?
B.E.

You are judged not by what you know, but by what you can do.

 

[robyengIT]

after one month we did not understand what kind of machine it is and what kind of job it does : why don't we stop to talk about ??