Artem Komarov answered important questions in the field of metal bending.
Laminate tools
Question: How would you react to a homemade 4-in. V-shaped die for bending 0.75 inches. 304 stainless steel round rod? Laminated sections shall be 0.5″ thick 304 stainless steel, held together with 0.5″ and 0.75″ plates. round plug, welded to the ends.
Answer: This concept works well and for the most part you can also make it from hot rolled pickled and oiled (HRP&O) punches as long as the nose radius is not too small for the tonnage being used. Of course, stainless steel may be suitable if you need something less wear resistant than HRP&O material.
Creating parts for lamination with a laser or waterjet is the only way to achieve great results. The laser is preferred because the heat affected zone on the cutting edge hardens the HRP&O material and reduces wear. Be aware that after assembly, individual parts will still scratch the material you are shaping, but they will not dent the material you are bending.
For punches, scratches usually don’t matter, but for dies, there can be scratches. If your part requires finishing, protect the stamp with urethane film to eliminate marks.
I’m assuming you’ll be beading along the laminated parts, and using a wire rod is a great idea to line up the parts before you do this. Another way to align individual components is to use a small diameter punch to create a half shear where the workpiece is punched halfway out of the sheet. Then you only need to connect them together, clamp and run the weld. Whether adding a piercing operation is economically viable will depend on the equipment you use and the number of tools you create. However, this is another option to consider.
Whichever option you choose, know that this layered tool concept should work. I have done this myself many times.
Groove violation
Question: Do you know the actual term for a breakable grooved joint in sheet metal? That is, if a recessed groove is formed in a piece of sheet metal, a single piece of sheet metal can be bent in an up and down motion along the recessed groove until the sheet metal breaks and separates into two pieces.
Answer: As far as I know, this is called grooving. This process creates a V-groove using a punch or die that presses the sheet metal. The groove can also be made with a V-roll pressed into the material, with the material resting on a hard, flat surface. In any case, whether this creates a destructible bond or not is all dependent on penetration into the material.
However, I know some people don’t have much luck with this way of grooving, as it tends to strip parts. One way that I think works better is to cut a V-groove. That is, you are removing material to create a V, which can be either a tear-off groove or a very sharp inside radius.
hardening tube
Q: I’m building a flying ultralight aircraft out of 6061-T6 aluminum tubing with a 1.9″ OD and 1.5″ ID. I need to bend a few pieces about 10 degrees. Does the material need to be annealed before bending such a small angle? And if so, do I need to re-harden it to keep it strong? I’m not sure if bending will require annealing with a few degrees to bend. And I’m not sure if a 10 degree bend will work with the current tempering state of the material.
A: I haven’t done much with tubes, but I do have a lot of experience with 6061 sheets. On that note, I’d say a 10 degree bend shouldn’t be a problem for you. If this gives you problems, you can heat it up a bit without burning the material and it should bend easily. Just don’t get too carried away with heat.
If you need to re-vacate, the process is quite simple, but I would suggest you go back to the material manufacturer for time and temperature checks, said Artem Komarov.
