Active Pitchcontrol

[diy]

Hey Rinus. What is the diameter of the balls, and where did you get them?
Rgds. Do

[mbouwer]

Hi Do,

The diameter of the balls is 15 mm, and we took them out of other used bearings.
We would like to improve the making technique of our bearing and besides that use ceramic balls. But where to get them low budget?

Rgds Rinus

[Frank S]

bearing houses should carry an assortment of balls

[fabricator]

You can order different types of balls from McMaster Carr, although shipping over seas would probably be costly.

[mbouwer]

Thanks Frank S and Fabricator,

At this moment we have enough used bearings to provide the balls for the new single main bearing.
But it would be nice if we could find low priced ceramic balls.
And instead of steel bearingrings what to think of composite?
Then once we have made a mould, we could provide other windmillfriends with a single main bearing.
The application of active pitchcontrol becomes a lot easier then.

Rgds Rinus

[Frank S]

At a place in FT Worth Tx called Bearings INC I used to buy nylon, Rubber, Silicone, Ceramic Steel, brass, & balls made out of UHMW for various applications some forbearing use others for valves
 here is a link for steel & ceramic
http://www.vxb.com/page/bearings/CTGY/Bearing Balls the 2nd page has larger sizes
if you are using the mon a turbine the only reason I can see to use ceramic would be lubrication
 one note ceramic balls do not like high impact forces without perfect race radius contours

[mbouwer]

Hi Frank S,

Thank you for your referring.
Here in Holland where almost everyone is connected to the grid, our intention is to build a small real profitable turbine.
Profitable means that we have a few issues that we must avoid.
High expenses is one of them. Weight is another.
So its impossible to BUY that bearing diameter of  300 mm  diameter
What we need is creativity from several disciplines working together to create components,
like constructing a ridgid light weight single main bearing.

Rgds Rinus

[fabricator]

Why do you need a 300 mm main bearing?

[Frank S]

Hi Rinus;
 Machining the upper and lower bearing races is no big deal in the 300 to 350 mm dia range
 you can either do it like Fab dit with a rotort table and a ball mill on his Bridgeport mill.
 ir like we do for the jib cranes I build on a lathe  any good medium carbon machinable steel will work for the races and can be flash hardened quite easily in an induction furnace or by torch. You do not need to get them super hard if it will be a Yaw bearing since it will never be rotating at speed. A turbine bearing is a little more involved and should be precision ground after hardening
  here is one that is just about 300 mm in diameter 20mm balls I didn't even bother to harden the races just used them as machined 50kips steel and was used in a 2 ton jib crane 5 meter beam length almost all of the bearings we do are angular contact.
 the nice thing about doing your own is you can design them the way you want them. the Jib crane has been in service since 2004 and has been relocated to 3 different buildings so far. 

[dloefffler]

Very nice work, how would they be ground for speed?

Dennis

[Frank S]

one way would be to have a rotating profile tool holder mounted to the tool post with a grinder like a do-more
 another way would be to mount a grinding stick that had been ground to the correct radius in the holder
 however if a custom ground piece of tooling stock had been used to machine the grove and finished off with high Rpm low cut feed little if any  grinding would need to be done just polishing after hardening

[dloefffler]

Thanks for the reply.


In making the gooves for the ball bearings, do you use an off the shelf tool with a given radius?

Again, nice work.


Dennis

[mbouwer]

Why do you need a 300 mm main bearing?

Hi Fabricator,
We are vey impressed by the professional turbines like Darwind, Enercon, Siemens..........
and want to make small working models of them, using the latest modern windmill techniques.
As well as we are working on other components, we try to construct and improve a light and ridgid single main bearing.
Cooperation with other windmillfriends is what we nead.

Rgds Rinus

[Frank S]

since none of my lathes at the shop are CNC and off the shelf inserts are expensive in this country plus being very limited in sizes or shapes hand ground tooling is mostly what we use for any custom shapes.

[fabricator]

Why do you need a 300 mm main bearing?

Hi Fabricator,
We are vey impressed by the professional turbines like Darwind, Enercon, Siemens..........
and want to make small working models of them, using the latest modern windmill techniques.
As well as we are working on other components, we try to construct and improve a light and ridgid single main bearing.
Cooperation with other windmillfriends is what we nead.

Rgds Rinus

If you want cooperation we need to know where this bearing is located on the machine, is it the yaw bearing?

[dloefffler]

Impressive job of hand ground tooling. Old school. It really did the job and still does.

Dennis

[fabricator]

In my experience at least I can never get the finish on a part with store bought inserts, than I can get with a good old fashioned hand ground piece of HSS.

[Frank S]

In my experience at least I can never get the finish on a part with store bought inserts, than I can get with a good old fashioned hand ground piece of HSS.

 good analogy

for high speed production where I can allow myself to really plunge into the  work piece I'll chose the inserts any day of the week.
 for most other things I silver braze an old insert on to a piece of tool bar then grind to suit
 for still other where I really need to get down and dirty so to speak with the shapes or finish  a chunk of HSS gets to meet the rock then very carefully finished off with a ceramic honing stone like you would use to sharpen a surgeon's scalpel  or your best fillet knife

 The yellow titanium oxide coated inserts are great for speed if you flood with coolant oil like lubrisol  but their main advantage is the  made in chip breaker , to over come this with HSS or carbide I either have to grind in my own or adjust the rake angle
 Tools are made to serve man not the other way around

[mbouwer]

To fabricator and other windmillfriends this quick sketch
rgds Rinus
[/img]

[Frank S]

Unless there is something that I am not seeing you are trying to use a single bearing to support your blades.
 What you are trying to do is to create a bearing like is used on a slewing ring of a crane or an excavator

these bearings are normally very low RPM or intermittent rotation
here is a catalog
http://www.kaydonbearings.com/downloads/catalog390/Kaydon_Catalog_390.pdf
 search page 64 for the MT series

[Frank S]

if I were going to think about doing this the bearing design I would go with does not exist
 so I would make the races a 1 piece outer and a 2 piece inner the inner races would be held together by the mounting bolts this way you can load the balls or replace them otherwise to load the balls in a regular slew bearing you must shrink the inner and expand the outer
 note the drawing I made

[Frank S]

actually this would be better since it  interlocks the 2 inner races

[fabricator]

Exactly, a bearing like in the drawing would have to be pressed together in a large press with a lot lf pressure.
I would venture to bet that the bearing Frank drew is very close to what the big boys use, they certainly would not use a single two piece bearing.

[Frank S]

Fab; as I see it  using a 3 piece race design allows for easier rebuild closer fit & finish between the inner and outer races without the need to have a loading hole which would have to have a precision fit plug
 also would be cheaper to make even with having to fit the 2 inner races together before the ball grove was cut.

[fabricator]

No question about it.

[Frank S]

with a turbine there are more than 2 forces at work though  while a single row 3 point contact slewing bearing as I drew would work in theory since it can withstand thrust and radial to an extent Moment as well however this severely limits the speed at which it can rotate continuously.
 To have speed we must have a couple more factors clearances being one of these
. if the bearing is made with too much then it cannot hold true rotational direction it would either wobble or vibrate causing still more problems one of these would be impact loading
 The best way to reduce this would be what is called preload  for a 2 point contact preload  is easy to accomplish.
 not so with a 4 point contact since this causes friction and wear
 so the way around this  most use taper roller bearings facing opposite of each other now radial , thrust and moment are reasonably controlled . But there is a problem tapered bearings of large internal and external diameters are also very thick and heavy
 There are ultra slim tapered bearings  and they are 100 times the price of a much smaller set of bearings which would have the design capacity for the turbine to run on
 Angular contact ball bearings share many of the same design qualities of taper bearings it takes 2.
  Ford and Nash were among the last car makers to switch from angular contact ball bearings to taper roller bearings in the front wheels
 So this brings us to thrust ball bearings it takes 2 to control thrust and moment but they do not do well with radial
 What we need is a bearing that exhibits the capacity to handle thrust both positive and negative angular moments and radial loads all at the same time
 we could either just use 2 angular contact bearings or 3 thrust bearings plus a radial bearing or 2 taper roller bearings Or the one single row slew bearing similar to what I have previously posted and be satisfied. All of these have their merits and short comings
 In the contemplated design the designer has shown that he wishes to have a large internal diameter he has  his reasons for this.
 The complicated and tedious machining to make ultra slim taper roller bearings and the fact that 2 would be required NIX's this one
  The need for 3 bearings 2+1 for thrust & radial NIX's this one
 leaving angular contact meaning 2 NIX!
 or the slew bearing, Viable but with issues.
 It seams we are out of options or one might think they were.
  Never fear back in 1947 a company in Sweden used to build radial arm drill presses in their Quill there was a single bearing that could handle thrust in 2 directions and radial loads. I know this because I used to own one of those drill presses the problem was the 50 year old quill bearing finally failed and I could not find a replacement so I did what any Texas redneck would do I machined out the Quill and installed 2 thrust and a radial bearing in its place.
 When what I should have done was to machine a new bearing housing and buy replacement balls
 the drawing below is a rendition in much larger form of that bearing

 it consists of a single outer race which could be press fit into a housing or machined large enough to be drilled for mounting bolts. 3 rows of balls 2 will take thrust and some radial plus handle any angular moment loading  the center row of smaller balls would take care of any radial loading. due to the contact angles no ball receives more than a 2 point contact friction and wear is greatly reduced allowing for higher RPMs

[mbouwer]

In the reactions of Frank S and Fabricator I learned a lot.
With all the knowledge shown, I would like to ask to keep thinking along with us.
More and more the big boys use single main bearings on their turbines.
The weight, number of parts, cost etc. become reduced.
Those bearings are very complicated because of the fantastic forces that have to be withstanded.
For our small turbines ( e.g. diameter 5 meter ) the load is rather low and calculable,
We think for us it would also be an improvement to use single main bearings.
It is not really simple to make a leight weight low budget design, but in cooperation there is a good chance we will succeed.

Rinus

[dloefffler]

Dumb question.

In the slewing bearings, how do you get the balls in place? The inner and outer races appear to be one piece.

In the drawing with the 3 sets of bearings, how do you keep them from falling out when assembling?


Dennis

[Frank S]

Dumb question.

In the slewing bearings, how do you get the balls in place? The inner and outer races appear to be one piece.

In the drawing with the 3 sets of bearings, how do you keep them from falling out when assembling?


Dennis

In my drawings on posts 284 & 285 the inner race is 2 pieces in assembly of anything with ball bearings there is a thing called grease that is impossible to get by without some of the very tedious micro precision instrument bearings are assembled in their factories by using a low level electromagnetic current applied to a race just enough current to aid in holding things in place but not enough to cause any residual magnetism in the race or the balls when non magnetic materials and in many cases where they are a special tool that is on the end of a robotic arm plunges into a tub of balls and one ball is picked up for each hole that the disc has using vacuum.
 in the cases  of a slew bearing the inner and outer races have very little gap between them then either there is a loading hole located in one race or the other and a fitted plug with an end profile that matches the race  is inserted to fill the hole  Or one race is shrunk using cold while the other is warmed by heat contracting the diameter of the inner while expanding the diameter of the outer another method that is next to impossible to detect is the outer race has a cut across it allowing it to expand like a woman's bracelet or a magicians set of magic rings. Bearing makers have more secrets to their methods than the CIA ever had.
 When I was installing a conveyor system at PTC Components INC a division of link belt they warned me that if I heard one of their large bearing races hit the floor not to look around to see what was happening but to duck and cover as if an atom bomb was going off because the wedge that was holding the ends of a race separated could shoot out at mach 5

[fabricator]

I that case you wouldn't hear the race hit the floor if the wedge got you.

[midwoud1]

Travelling in Poland .
I see the item big mainbearing.(Hub suspension)
Another reason that Rinus is talking about a big mainbearing as I understand .
To bring the pitch actuator in front of the hub as far as possible.
Being compact fit and short linked in the Enercon model nacelle.

- Frans -

[Frank S]

Franz it can do another thing as well having a big through hole affords an easier way to add  gearing however
 redesign of the rotor placing a large thin bearing on the turbine side and one on the back side  would serve even better
 I'll draw up a double axial stator with a triple rotor as a case scenario to show my perspective tomorrow.

[fabricator]

I don't see the need for such a thing in a small turbine, you could take Frans's design and simply use a larger main shaft, say 3" chrome moly steel and drastically shorten the distance between the main bearing pillow blocks and use a shorter actuator mounted under the pillow blocks as a pull instead of a push.
You could shorten Fran's nacell by half at least, not that there is anything wrong with it as it is now.