Precise-High Capacity Material Handling

[ChrisConley]

I have an application where large dipolar magnets, weighing around 7000 lb, need to be moved on to a table. The catch is that the magnets need to be placed with great accuracy into position (around 1/100 inch tolerance).

My thought is to use a forklift-like device that could lift, manouver and then precisely place these magnets. My question is: does anyone manufacture a device such as this? Alternately can anyone think of an other way to move a heavy object such as this, with the accuracy that is required?

Hopefully I have been clear enough in my description, but feel free to request additional information.

 

[prex]

Have a look at

http://www.levitans.com

: air bearing pads may be a solution, though of course only for positioning, not for lifting.
I suppose you want a fast a straight operation, otherwise why not using jack screws for displacing the object after it is laid down onto the table? prex
motori@xcalcsREMOVE.com

http://www.xcalcs.com

Online tools for structural design

 

[RobWard]

Is this repetitive work? If so a large industrial robot could do it.
Not cheap though.

 

[ChrisConley]

To respond to your questions:

1) The reason I'm looking for the tight accuracy for positioning is that these magnets have to be placed on the table around a vacuum tube that is already in place. The magnets are C shaped where the gap that they have for fitting around this vacuum tube is around 1/100 inch. So they must be picked up, and then carefully moved into position. Once in place positioning screws are attached to the magnet and the lifting device can be retracted.

2) This isn't really repetitive work. There are a couple dozen magnets to be positioned, but then they will never be touched again. I did think of a robot, but the cost for such a small number was prohibitive.

And as a side note, I made an error in units in my previous post. The magnets weigh 7000 kg each.

 

[Hush]

Why not use locator pins?

 

[butelja]

If these are permanent magnets, I would think that your biggest problem will be the magnets either attracting or repelling each other. You must find out what types of attractive or repulsive forces are to be expected. You certainly don't want 7,000 kg magnets leaping through space unexpectedly. If they are electromagnets, disregard my previous statements.

If this is not a problem, then locator (dowel) pins seem to be a sufficient solution to the problem.

 

[prex]

If the positioning movement is essentially vertical and you can count on some degree of auto centering (of course the magnet will get into contact with the vacuum tube, does it matter?), I think you should attach the magnet to a cable by means of a lifting tool that allows for leveling, and then go with a crane having a very low vertical speed. If you can put shims before positioning, you could obtain the required gap quite easily.
On the contrary, if the magnet cannot touch the tube, this seems a big challenge.
Anyway don't know of any off the shelf device that can do such things. prex
motori@xcalcsREMOVE.com

http://www.xcalcs.com

Online tools for structural design

 

[trihydrate]

Would it be possible to locate the magnets and machine the "hole" if necessary and then install the vacuum tube?

 

[ChrisConley]

To respond to all questions:

1) These are not permanent magnets so there is no 'attraction issue'

2) The magnets cannot touch the tube, the tube is fragile, and in addition has been carefully calibrated.

3) The magnets are preformed and already exist, as a result they cannot be shaped in any way.

I feel I should clarify slightly. The magnets are 7000 kg electromagnets that are staggered around a 200 yard circle of vacuum tube. The magnets act as boosters to keep accelerated electrons at a constant speed through the loop. The magnets are shaped such that they must be lifted up to the level of the vacuum tube (vertical) and then slid over onto a table, such that they surround the tube...without touching it at any time.

Currently what is being considered is using the onsite crane to lift the magnets onto an adjacent-temporary table. From the table they will be moved over to position in there permanent locations. This is the current solution I'm examining, but was hoping to hear if anyone else had an alternate solution.

 

Assuming tubes are rather expensive!!
I would suggest air bearing pads (standard item for moving heavy equipment)used in conjunction with some dead stop type of locating device. May consider using jack screws, or similar, to locate, remove from air pads, and then lower to final resting place.

 

[MarkWPflow]

This type of equipment can be built. For instance, we have designed, manufactured, and installed a three-axis lifting and positioning system for 300,000 lb. fuel cells in the manufacturing assembly process. But if you can truly accomplish what you need through the use of a crane and some tables, it's probably not cost effective to purchase a custom designed lifting/positioning system. As suggested, some type of fixed location device like tapered pins that can be pre-placed seems to make a lot of sense. You might also try contacting machinery movers and see what they suggest. I'm not sure they normally work within the tolerance you're talking about, but they might have some ideas.

Good luck!

Mark Webster
VP Engineering
Pflow Industries, Inc.
Vertical Material Handling
Milwaukee, WI
markw@pflow.com

http://www.pflow.com

 

[charlie300]

Using a positioning fixture seems like the most practical, cheapest method. Maybe a rod that fits under the U shape. Some other hardened features that gudie position on the outside of the Magnet.

Maybe a plate with the profile of the magnet cut just right over the work piece. You could use an overhead crane for the lifting.

Charlie