enginehistory.org

dpennings · Joined: 10 Dec 2016 Posts: 48

in case you're intrested, here you can find an alternative to the Hirth joint when you scrall down to the pictures:

https://depatisnet.dpma.de/DepatisNet/depatisnet?window=1&space=menu&content=treffer&action=pdf&docid=DE102019003501A1&Cl=5&Bi=1&Ab=&De=2&Dr=7&Pts=&Pa=&We=&Sr=&Eam=&Cor=&Aa=&so=asc&sf=vn&firstdoc=1&NrFaxPages=14&pdfpage=1&xxxfull=1

rwahlgren · Joined: 15 Aug 2003 Posts: 323

No pictures seen on this link. It says error page with hyper text or ?

dpennings · Joined: 10 Dec 2016 Posts: 48

OK, let's try it with google:

https://patents.google.com/patent/DE102019003501A1/en?oq=DE102019003501A1

it might be a little bit weeker when it comes to high torque, but much easier to machine and works very well...

rwahlgren · Joined: 15 Aug 2003 Posts: 323

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.

dpennings · Joined: 10 Dec 2016 Posts: 48

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.

rwahlgren · Joined: 15 Aug 2003 Posts: 323

To sum it up. What Pratt & Whitney did was the better option, like Kim said.

dpennings · Joined: 10 Dec 2016 Posts: 48

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.

rwahlgren · Joined: 15 Aug 2003 Posts: 323

"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

dpennings · Joined: 10 Dec 2016 Posts: 48

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.

rwahlgren · Joined: 15 Aug 2003 Posts: 323

rwahlgren · Joined: 15 Aug 2003 Posts: 323

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.

kmccutcheon · Posted: Mon Jan 25, 2021 19:14 Post subject:

dpennings · Joined: 10 Dec 2016 Posts: 48

I think, that's true

https://en.wikipedia.org/wiki/Heavy_Press_Program

kmccutcheon · Posted: Tue Jan 26, 2021 10:38 Post subject:

wallan · Joined: 13 Jul 2003 Posts: 252 Location: UK

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.