Practical Ball Wheels for a crucible pouring tool

I'd been thinking of how useful it would be to have a crucible pouring tool that could move across the foundry floor in all directions. There's a type of wheel called the Omniwheel which can do this but it has a lot of parts. This video shows a much simpler design of wheel originally created by Osaka university: it has two hemispheres each with a roller on each "pole" of the hemisphere where the wheel can't roll. Imagine casting some aluminium hemispheres, fitting two bearings each, an axle and two end rollers to get a two axis wheel. At the 12 second mark you can see a drawing of it's construction and at the 11:43 mark you can see the wheel in operation.

 

Mark, that is a very clever and totally new-to-me design.

Then there is applying in the real world. Having used a conventional two-wheeled pouring trolley for a few years now, I fear the complete freedom of movement might actually be a detriment. That’s because tilting inputs would also be “contaminated” with traversing inputs unless the user was perfectly coordinated. So, hitting the pouring basin and maintaining an accurate pour stream would be a very squirrelly affair.

My take is that I am enchanted by the cool factor. But I recognize that I am not cool enough to use it. BUT, maybe if one could put a handbrake similar to a bike handbrake to lock up the wheels when tilting the crucible, then it might work. The other caveat is that the foundry floor better be very level (concrete is often poured with a drain slope) or moving where you intend to push it might be challenging. That is why I opt for only two of four casters on my various carts to be on pivots. Carts with four pivots can be very hard to steer. In one case I have a heavy cart on four pivots, but I can lock two of them with pins. I use it almost all the time with only two casters free to pivot.

Sorry to be a spoilsport.

Denis

 

I'd been thinking of the ergonomics of it and thought it may be possible to have a straight pouring shank with two of those ball wheels closer to the crucible end. Like you say a smooth concrete floor and brakes are going to be needed. It would be nice to eliminate the backing and filling of normal two wheel pouring shanks. Other ideas on a flat concrete floor would be a cushion of air type lifter, say a plywood disc with a bike tyre for a flexible skirt using compressed air for the lift when positioning it. Over a disc of say 20" you'd only need ten PSI from a regulator fed to a control valve to lift a full crucible. Molten metal and compressed air hoses don't play well together, imagine a burst air hose spraying spilled molten iron everywhere.

 

Since a two-wheeled trolley is so much simpler to build and is a proven design, I’d suggest making one, using it a while, and the deciding if a novel design is needed. There are enough design considerations in the tilting mechanism and geometry to work out for a trolley regardless of the means by which it rolls. Work them out there. I think you will find that compactness, robustness, and ruggedness of a traversing mechanism is important

Foundry environments tend to not dispose themselves to ideal surfaces for Omni-directional balls or air bearings. Sand, minor metal spills, cracks in concrete, etc conspire against high-tech solutions.

Summary: There are so many other more pressing problems to work out. But who knows?

Denis

 

The ball rollers are a big unknown in how they handle and if they have some sort of "over center" toppling effect between the hemispheres like a swinging castor wheel does. The other ideas I'd been thinking of was a swinging overhead arm with an electric hoist as well as a turntable: I have fairly substantial 3" steel axle with opposed tapered rollers from an industrial washing machine as well as a 6' diameter x 3/8" thick steel disc: it could make a knee high rotating disc for sand moulds to sit on while pouring. One advantage of having a wheeled pouring shank is the extra volume vs surface area of a larger crucible gives you more time at temperature. I can notice the difference between an A16 and an A20 of bronze in that we have to have the bronze hotter and pour faster with the A16 than with the A20 all other things being equal. So going up to an A25 or larger on wheels would buy a little time when pouring.

 

Mark,

Kelly has worked out a beam/trolly arrangement that works very well for him. If I had a space in which I could set up semi-permanently without concern for complaints by neighbors, I would install a jib crane or fixed or pivoting beam and hoist system. Since the actual loads placed on the crane or beam are small, its reach could be pretty long. For instance, if a person had a simple fixed steel beam of, say, 1X3 (just guessing here---no engineering), it could carry the 130 to 180 pound loads involved in full A25, grappling, and hoist gear over a long span---20 feet? If one imagines a line of molds set up to pour along that track, plus a simple electric hoist and a lever on the hoist gear to tilt the crucible, it is not hard to envision a very handy setup. And the whole beam fabrication, hoist mechanism and control pendant are off-the-shelf. The hoisting gear would require fabrication, but there are lots of good examples of proven designs on this site. No "new art" is required. Fabrication time is minimal, really, with known functional results. In the unlikely event that one outgrew such a simple fixed setup, the end near the furnace could be made to pivot and the outboard end could be on an A-frame of two wheels. (Very much reminiscent of the proven design of irrigation pivot technology,) Now you could have radiating spokes of molds.



In our foundry world the pivoting end would be a simple vertical steel pole and bearing---no need for the complex design above.

Denis