Hydroforming steel balls

I was wondering if anyone has experience with (non-explosive) hydroforming steel balls.

As seen in this example of explosive hydroforming…

… it looks like the steel is cut and welded in such a way that the cross section is a regular polygon, but is this really the case?

It’s for a student project at the Design Academy Eindhoven, where we want to experiment with this technique. Thanks in advance for any info on this topic that you can share!

fascinating stuff. Here’s one creating a ball without explosion:
https://youtu.be/fBo7UbI6FMk?t=299 (at the 5min mark)


yes, I’ve seen that one as well :slight_smile: even with just two sheets the ball gets pretty round! Maybe it doesn’t need to be very accurate as the forces will even things out…

no idea, but it doesn’t seem to me that the shape would naturally tend to end up in a sphere. I wonder if Kangaroo could help here: Non Uniform Plastic Inflation Simulation (Kangaroo2)

no experience forming steel balls non-explosively but do have experience hydro-forming 304 stainless steel exhaust system components at both 5,000psi and 10,000psi. hydraulic power-packs are readily available; the cost is in the tooling for the shape/surface finish you’re interested in forming. the other key factor to take into consideration is the amount of strain that will be required to get from your “blank” to your finished shape given your minimum thickness requirement. the part in the picture below had to be annealed in a vacuum furnace three times to achieve the required shape! none of my work was done with the objective of exploiting strain rate phenomena; everything was done slowly with manual valves.


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It might be fun to be driving by on the road when the charges go off.