Drill that spins and feeds shaft forward, How does it work?

[Scipio236]

The video below shows a drill that has a long center shaft which feeds in one operation and spins in another. The big difference with this drill compared to others is the shaft is not connected in line with the motor. The purpose of this seems so that the shaft can slide in and out and the motor can stay in on location. Can some one explain to me how they think this would work? It looks like the spinning of the drill is one operation controlled by the pulley and belt clearly seen and the forward backward motion is another operation that is controlled by some type of clutch mechanism?

https://www.youtube.com/watch?v=7A_Jwa1t6IA

Any help on this would be great.

Thank you

 

[MikeHalloran]

Splines or a polygon drive would probably get fouled pretty fast.
I'm guessing it's driven by friction both rotationally and axially.




Mike Halloran
Pembroke Pines, FL, USA

 

[tbuelna]

From what I could see the drill feed is performed manually by the operator.

There are probably a couple reason the drive motor is offset and uses a belt drive. First, it makes it easier to feed coolant thru the spindle to the drill bit. Second, it isolates the drive motor from excessive radial/axial forces produced by the very long and slender spindle shaft. Third, the belt drive provides overload protection for the motor when the drill bit seizes up. Rubber belts are cheap and easy to replace.

 

[3DDave]

I suspect the main body is a hydraulic cylinder that pushes a rod that contains bearings for the drill. I looked at the Hydrodrill(tm) manufacturer website and didn't see any feature that suggested something else, but maybe I misunderstood.

 

[Scipio236]

Still not sure how everyone things it moves forward.

From the video it seems that the device the shaft is going through also moves it forward. Do you think it moves forward with some sort of gearing mechanism? 3DDave and Mikehalloran, do you think that hydraulic cylinder or polygon drive are at the other end of the shaft (off camera) or that the shaft is going through those? tubelna, do you think an operator off camera is pushing the shaft forward?

 

[3DDave]

Spend some time at the manufacturer (Hydrodrill) website or drop them an e-mail. Probably the quickest way to find out.

 

[SwinnyGG]

The shaft moves forward hydraulically. There are a million videos of these things working, beyond what you just posted.

The force required to push a large bit that far, that fast, is much more than could be provided by one average man.

 

[mfgenggear]

nifty tool, lot of vibration thou. My bet Hydraulic. but to much over hang thus less rigidity.

 

[Scipio236]

jgKRI,

What type of hydraulic device would be pushing this forward. My biggest question about this is how does the shaft push through the center? If it was threaded I could see it being pushed with some sort of gearing mechanism powered by a hydraulic motor. The shaft does not appear to be threaded so what is actually grabbing the shaft and pushing it forward??

 

[MikeHalloran]

Easiest way of all: The shaft becomes the rod of a hydraulic cylinder.
Put a piston on the distal end or don't; it just affects the effective area; either way, pushing oil into the cap squirts the shaft out.

Of course, that's not the only way to do it. I followed a couple of links from the video to a competitor's machine that uses a double caterpillar friction drive for pushing and pulling the drill shank, which in that case is just a piece of flexible tubing or a very stiff hose.



Mike Halloran
Pembroke Pines, FL, USA

 

[hydtools]

I suspect the rotary drive is a hex or square like a Kelly bar drive a known art in drilling. There is probably a rotary water union at the back end of the shaft. Since the rotary union would need some means to counter rotation there may be some traveling device to do that and provide push to feed the shaft. Pneumatic power is probably used. Constant pressure on the feed would be set to be less than the buckling force of the shaft and feed speed would depend on how loaded or unloaded is the drill bit. For long drill steel, we would use an intermediate guide to prevent drill steel bending.

Ted