Make a Hole On Barrel Nut, Which Has Been Assembled On Wind-Power Station

Ho about a carbide bit?

Yes,It can.But how to carry the machine,it's on the 70M higher.And I only can get in the geneter room through the hole which diameter is 0.5 meter.

What are the dimensions (diameter and depth) of the hole you want to make?

Another cheap N dirty trick

Use a pipe nipple as a drill guide

or make some custom guides to slip in the, drill a mild steel stud on a lathe

tack a nut to the stud, so it doesn't get stuck in the hole too :D

What exactly are we looking at here? The internal-tooth ring gear seems to be fastened down by too many studs and nuts, with a few too many washers, and probably overkill metallurgy. What is the dark spot in the lower center of the picture? "Barrel nut" is odd terminology; what does it mean? There are devices called "nut splittesr" that can cut nuts in half, but I don't know off hand whether they exceed RHC 32.

Trust me; Slewing Ring applications like this are under significant load. The use of fewer fasteners would likely result in the nacelle toppling over. I believe that the "extra" washers that you see are actually spacers used to increase the grip length of the joint.

In such a critical application, close adherance to correct bolt load is paramount. Hence, frequent preload verifications are routine (or should be!)

I don't know if it's practical or not, but electrical discharge machining may be an option.

Wouldn't this be a nice thing to have in your tool box?

Then there is the poor man's EDM: a carbon arc welding rod, a compressed air nozzle, and nerves of steel.

...and earplugs.

& leathers

When i get into drilling high strength heat treated or just very hard metals I usually take a common carbide tipped missionary drill bit and resharpen the carbide tip to the shape and cutting angle like whats on a regular steel drill bit. I have yet to find a metal I couldn't drill through that way.

Big holes do need to be done in steps though.

The next best option is a plasma cutter. They don't care about what or how hard the material is they cut just so long as its conductive.

Otto - Cut the nut off with a narrow (1.0 mm thick; 5 to 8 cm diamenter) reinforced cutoff abrasive disk in a high speed die grinder (air or electric). Note you will need a mandrel to hold the disk and adapt it to be driven through the collet on the power tool output shaft. The cut is made approximately tangential to the stud OD deep enough into the washers to completely split the nut. The grinding wheel turning at 12 to 20 thousand rpm will easily cut through fully hardened steel. If you have 5 cm clearance over the nut then you can access the location with the die grinder from the same location as your camera that tool the photo.

If need be I can take a picture of one of these tools and post it here.

We don't know where you are located. Thus the availability of hand tool that I describe is unknown to those of us trying to help.. But there is a good chance the power tool as well as the cutting disks are available from McMaster Carr Hardware in the USA. They have an excellent website, are set up to ship anywhere in the world via air and take major credit cards to simplify currency conversions. And their prices are reasonable running somewhere around 150% of retail prices in the USA on common tools. This is quite reasonable for a plant maintenance emergency that involves costly equipment downtime.

Ed Weldon

Guys, a barrel nut is in its simplest form is a length of round stock with a threaded hole at right angles to the length of stock. In reality it is made from a self locking half round nut backed up with a suitable spring clip feature. The installed nut assembly is located in a hole at right angles to the stud. I think I would enjoy watching otto using an abrasive disk as he describes. The carnage would be brilliant. Depending on access you need to either drill out the stud or drlll out the barrel nut. I personally would stage drill the stud, after determining the depth to just past the far side of the nut. Drill too far and you will be in deep dodo. good luck

Correct.

A good assumption is that, in the picture, the end of the barrel nut is the round thing near the bottom of the picture. The other nuts, the hex nuts shown in the picture, are removed with a thing called a wrench.

Joey - In all my experience in mechanical engineering I never heard this fastener called a barrel nut. So I learned something new. Clearly my previous suggestions in reply #5 are not applicable here. This is the problem with poorly framed questions from cultures that may well use technical terms not familiar to us in the USA.

Now that I think I have a better understanding of the problem my suggestion is to use a high quality magnetic base portable drill and a carbide tool bit to drill out the cylindrical "nut". Use a cutting tool diameter as close to the diameter of the cylindrical nut as you can get given your capabilities for aligning the spindle centerline with the nut centerline. Slow speed and a good sulphur based cutting oil are called for.

I had some experience with magnetic based drills when I worked as a plant engineer in the iron foundry and I can tell you that they are well worth the 4 figure investment they pose. A high quality one will have a spindle rigid enough to handle center cutting end mills in a straight plunge cut. This is a really cool way to deal with impossibly damaged fasteners and is a long step above trying to do the job with a hand held drill and trying to locate a center with a centerpunch. Also the solid mounting and fixed vertical alignment of the magnet base will make the use of brittle carbide cutter practical where it would otherwise be hopeless with the inevitable lateral movement of a hand held power drill.

Ed Weldon

Talk to the turbine manufacturer?

I can only think of one option That hasn't been mentioned

Left Handed Drillbit

you may get lucky & have the broken stud spin out

A diagram would be helpful as I am not exactly sure what I am looking at in the photo. I suspect Garthh may have the best answer as left handed bits can be a god send. Depending on the base material present, either a magnetic base drill or a suction base core type drill would ensure accuracy. If you can access a set of centering punches that exactly center your pilot hole, it would almost completely assure your success.

An angle drill will be helpfull, also drilling hard metals should be at very low speeds and with constant drilling fluid lubrication.

Double nut the stud and make the two nuts fast against each other. Then back it out turning the nut so that the forces cause then to still tighten against each other.

I can't discern the size of the stud from your photo. I assume that it's at least M36, correct?

"we only can manufacture the hole by hand drilller" Good luck. At the very least, get a mag-base drill to bore the fastener and then, collapse the threads. If this is beyond your capabilities, there are some very competent companies available which specialise in this type of in-situ repair. Based on the location of the wind farm, I'll provide you with some recommendations.

I agree with Tornado with his "nut splitter" tool, or tcmtech's suggestion about using a plasma cutter to remove the nut.

You could also use a torch to cut apart the nut, piece-by-piece, and then later to heat up/free-up the broken stud. I've used this technique many a time on broken engine exhaust manifold bolts....works like a charm too!

They do make massive ratcheted stud extractors for this type of scenario you know!

Good luck!

Gents,

Perhaps I'm out to lunch but, it seems to me that the affected stud in question is the partial one seen buried in the hole below the ring gear...

Mag-base drill.

What? You don't want to haul it up the tower? Well then, you might as well call it a day, go home and find another job

While we're at it, let's discuss a probable reason for this unfortunate problem so that it doesn't happen again:

I've seen this scenario many times. In fact, I just encountered something very similar while on a project in Africa. The contractor responsible for assembly of a rather large piece of process equipment inserted a number of M100 bolts into blind holes. Most went in without any issue. However, the millwright encoutered a couple that offered some resistance. So, not wanting to be bested by an obstinate bolt, the fellow increased his leverage on the tight bolt heads by using a long pipe wrench and an extension bar. By putting some effort into it, he was able to drive two bolts home. The third stopped turning with the head some 25mm from the spotface. Shortly thereafter I returned from lunch.

The mechanical contractor's foreman explained the situation. I immediately instructed them to remove each bolt that was installed in this manner. One came out without too much effort, another was stuck and, the third had snapped in the hole.

The root cause was, as I had suspected, due to pitch misalignment of the problematic holes. Since they weren't concentric, the threads met physical resistance. The more serious problem (stuck and broken bolts) was due to typical contractor response : If it doesn't go in, use more force!

Unfortunately, this action resulted in the bolts dragging through the threads of the bore. As one can imagine, the fasteners became galled.

In the above example, the second bolt eventually came out with a monster hydraulic torque wrench (yes, the hole had to be cleaned-up). The third, however, required in-situ machining (mag base drill).

A couple of things to keep in mind:

• If resistance is felt, STOP!
• Keep the cheater bars far, far away
• Just because a bolt head is snug up against the spotface and the "correct" torque was applied, one cannot assume that the joint is tight (the bolt certainly would be but, there may not be any clamp load holding the flanges together!)
  

You might build a drilling jig to hang over the gear that will keep your drill bit aliened with the broken bolt secured with a "C" clamp to aid in keeping everything in position. With this jig you could use a cordless drill yet have the stability that you need.

I envision a 4 inch wide hanger with a sliding section that can be centered over bolt with a drill guide.

This could be easley carried in a small bag up the 70 M to the work area.