Hello Mikeqc1, the other folks have given you some spot-on information. I would only add that depending upon the thickness of your material and how round the end product needs to be there are ways to approach the process to attain the best roundness. Material thickness will have a considerable effect on a rolling process. As the material thickness increases, the equipment and how it is set-up changes considerably. A simple rolling system basically uses a pyramid roll configuration, by moving the top roll downward between the two lower rolls you will tighten the bending radius achieved by the machine. Usually the bottom rolls are spaced apart based on the capacity of the machine, thickness wise. A light-duty, light gauge set of rolls will have relatively small diameter rolls and they will be located relatively close together to one another. A heavy duty roll with much more substantial thickness capacity will generally have much larger diameter rolls and the spacings between the rolls will be much greater. Because of these spacings you will have "flat spots" on the starting and ending portions of the rolled materials. If this is an issue for your rolled part you will need to approach the rolling process slightly differently. In one approach additional material will be added to each end of the piece and a portion of the ends will be rolled until they are at the appropriate finish radius, this will make the part look like a sled runner with upturned ends. Then before completing the rolling process the excess materials on the ends are cut-off.
Another possible approach can use an additional slightly thicker plate beneath the actual part. In this case you advance the thicker material into the rolls so that it has bridged the rolls and then feed the actual part between the first plate and the top roll. This method will allow the bottom heavier material to act as a bending shoe and form the ends of the actual part all the way out to it's ends. You still need to roll each end of the part so that it looks like the sled runner and the radius of these runner ends needs to be the same as the finished cylinder, yet in this case you don't need the additional material to be added or cut-off later in the process.
Still others will use a press brake to form the intial radius on the ends of the rolled piece, here again, this may require including additional materials on the ends to provide a radius all the way out to each end of the part.
Metal forming/rolling can be a pretty challenging type of work, yet it can also be rather enjoyable and rewarding when everything comes together as you have planned it. Sorry to get off on a tangent, I'm sure others will have plenty to add to what I have included here. Best regards, Allan
I also agree with all that's been said thus far.
In our fab dept. we roll and bend things all the time. Often times the parts will have complex profiles and tight tolerances to adhere to. Since our work is primarily machining, we will machine the part in the flat state, then bend them after, (whenever possible) and all the holes and other features need to fall into their locational tolerance after bending. It can really be a challange. But as long as you account for the bend radius and thickness of material, it can be nailed down to within +/-.010 on the length. If you have access to CAD software, it can make calculating real fast and easy, particularly on parts that have several bends that aren't at 90 deg.
Jason
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