Theoretical Analysis of the Tup-Motion of a Forging Air Hammer

[don schad]

Yes, it's true. Get out your slide rules and chart recorders. This is a 1961 journal publication from the Japan Society of Mechanical Engineers studying some of the physics of a big self contained hammer: paper. Click on the "FullText PDF" link for a scan of the paper.

There is a bunch of stuff which may or may not be interesting depending on ones orientation. It looks like they calculate the overall efficiency of a 500kg at 52%. There is a test similar to the "squish test" here (using a lead block).

Anyway, just thought people might find it interesting to look at.

don

[John Larson]

Interesting. But not sure what the usefulness was intended to be. The hammer is a Beche' that we also know state side as a Nazel. The indicator diagrams look very much like those I've seen from old literature that I think Nazel published.

Were there other articles about hammers in that same journal?

[don schad]

Were there other articles about hammers in that same journal?

You can search the archives there and join. If you can read Japanese then I think there is some additional stuff, including some more recent modeling. One that might be of interest involves anvil weight ratio calculation...paper. I only looked quickly but it seems their magic number is around 10 (anvil:tup), but he sort of dances about the issue of actually saying what it is, vaguely saying "certain values which are far smaller then what others have said can be seen in figure x...". It seems to also address the question of the importance of what's under the anvil (comparing infinitely massive bases to those floating in space). I think this section deserves further study, but at quick glance I think the answer is that it isn't significant.

don

[John Larson]

I read the hard copy again this morning and converted metric to inches etc. One important calculation (not emprics so far as I can tell) is that there is an optimal speed and for the particular machines he referenced I think it was about 120 rpm; 180 rpm was too fast. His horsepower numbers are quite large compared to what Grant has suggested for the Nazels in his life.

I'm wondering if use of sine waves would suffice instead of stressing the difficult approach he selected for life-like crank-connecting rod-piston motion modeling. The sine math allows easier differentiation and integration operations.

I have not yet looked at the paper you refernced today. But will.