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dpennings
Joined: 10 Dec 2016 Posts: 48
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rwahlgren
Joined: 15 Aug 2003 Posts: 323
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Posted: Mon Dec 14, 2020 16:50 Post subject: |
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No pictures seen on this link. It says error page with hyper text or ? |
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dpennings
Joined: 10 Dec 2016 Posts: 48
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rwahlgren
Joined: 15 Aug 2003 Posts: 323
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Posted: Tue Dec 15, 2020 12:59 Post subject: |
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Easy to machine? Not with the tolerances required for those steel balls or what ever they called them. If those radius holes are too deep then the joint is loose. If they are not deep enough then the joint has a gap.
Plus machining a true spherical hole would be very difficult.
If a ball nose end mill is used, you need to see how they are ground, also the central surface speed is close to nothing, in other words they barely cut at the center of the tool.
They could be EDM cut I suppose, all hole have to be exact or else there will be some that will be loose. I don't think EDM was available in the 40's?
Back in the days of radial engines that system would be far too costly to do, with such tolerance variables.
That's how I see those pictures. |
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dpennings
Joined: 10 Dec 2016 Posts: 48
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Posted: Tue Dec 15, 2020 13:39 Post subject: |
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I agree on you that it wouldn’t have been suitable for machining technic of the 1940 th, but with today machinery it is no problem at all, because you can mill them all in one clamping position. Neither the surface nor the geometry has to be perfect, the balls are pressing their seat so that the dimples looks polished after the screw is tightened up (the balls are made for ball bearings).
We built an engine with that and never had an issue with that solution, nothing comes loose and the FEM results were also positive. |
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rwahlgren
Joined: 15 Aug 2003 Posts: 323
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Posted: Tue Dec 15, 2020 16:47 Post subject: |
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To sum it up. What Pratt & Whitney did was the better option, like Kim said. |
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dpennings
Joined: 10 Dec 2016 Posts: 48
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Posted: Wed Dec 16, 2020 04:57 Post subject: |
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depends, you can't use the P&W solution for Boxer engines with a S-shaped crank shaft because you need to mashine it from the side. When using a divided crank shaft in Boxer engines, S-shape crank shafts are always prefered because of lower cylinder offset and thus lower mass forces, weight and engine length.
The mill has to do very comlex movement for the Gleason Joint compared to the Hirth Joint, not a problem today, but shurly in the 1940 th.
Also, you need higher bolt forces compared to the Hirth or our solution because of flatter angles on the contact surfaces. There must be reasons why the Hirth joint was still in use after the war whereas the Gleason face type seamed to have vanished with the P&W engines. |
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rwahlgren
Joined: 15 Aug 2003 Posts: 323
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Posted: Wed Dec 16, 2020 10:49 Post subject: |
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"The mill has to do very comlex movement for the Gleason Joint compared to the Hirth Joint, not a problem today, but shurly in the 1940 th. "
The above is what dpennings posted.
And that is the reason it is called a Gleason Joint.
They made the special gear machines to do it.
One of many in the video below.
https://www.youtube.com/watch?v=gj2szHk0OCU
Some history of Gleason.
https://en.wikipedia.org/wiki/Gleason_Corporation |
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dpennings
Joined: 10 Dec 2016 Posts: 48
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Posted: Wed Dec 16, 2020 12:11 Post subject: |
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I found a lot about their gearing, but nothing more about their joint. I don't see, how you can machine the joint with the machine you referred to, it must be something else.
The Hirth joint is still in use for many non engine applications and can still be found on crank shafts, but only on the front side (Audi, here it is forged, not milled). I couldn't find any other example for the Gleason joint other than the P&W engines. |
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rwahlgren
Joined: 15 Aug 2003 Posts: 323
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Posted: Wed Dec 16, 2020 15:55 Post subject: |
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dpennings wrote: | I found a lot about their gearing, but nothing more about their joint. I don't see, how you can machine the joint with the machine you referred to, it must be something else.
The Hirth joint is still in use for many non engine applications and can still be found on crank shafts, but only on the front side (Audi, here it is forged, not milled). I couldn't find any other example for the Gleason joint other than the P&W engines. |
The video was just one of their machines, to show what they (Gleason) are capable of. No a hypoid gear machine would not be for that application. They made one special for that application (P&W) I'm sure.
This sorta fits into the discussion.
https://www.geartechnology.com/issues/0585x/Tifco.pdf |
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rwahlgren
Joined: 15 Aug 2003 Posts: 323
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Posted: Sun Jan 24, 2021 18:59 Post subject: |
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Back to Crankcases. The article on this site mentions that the BMW801 used a CAST steel crankcase that was fully machined. Why didn't they forge it?
The cast steel crankcase is still many times stronger than a forged aluminum crankcase, only problem would be inclusions, and porosity, that could lead to cracks and failures. But then all materials can suffer from that. |
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kmccutcheon
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Joined: 13 Jul 2003 Posts: 298 Location: Huntsville, Alabama USA
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Posted: Mon Jan 25, 2021 19:14 Post subject: |
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Quote: | Why didn't they forge it? |
Probably because the huge drop hammers necessary to forge such large pieces were in short supply. _________________ Kimble D. McCutcheon |
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dpennings
Joined: 10 Dec 2016 Posts: 48
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kmccutcheon
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Joined: 13 Jul 2003 Posts: 298 Location: Huntsville, Alabama USA
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Posted: Tue Jan 26, 2021 10:38 Post subject: |
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Quote: | The article on this site mentions that the BMW801 used a CAST steel crankcase that was fully machined. |
I've never seen it documented, but they may have been centrifugally cast, which would have given much better material properties than traditional gravity casting. Ford found that its centrifugally cast cylinder barrels were better in all respect than P&W's forged barrels. _________________ Kimble D. McCutcheon |
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wallan
Joined: 13 Jul 2003 Posts: 252 Location: UK
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Posted: Wed Jan 27, 2021 02:17 Post subject: |
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BMW 801 cylinders were made from a disc, (slug; looks like a big ice hockey puck) of steel. These were heated and a ram pushed through it into a die to produce what looked like a tankard/beer stein without a handle. A hole was punched through the bottom and the inside pressed out to form a cylinder. This was then placed in a jig, rotated and a tool comprising of discs was pressed against it, to raise, (form) the fins and base, much like high quality threads are raised on fasteners.(better grain structure) I have a .pdf of how they are made. I will post it, later. |
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