Stator puller/extractor tool 2

[charlie821]

Hello,

I am looking for a tool to help remove old stator from their motor casing. We may try a modified 3-jaw internal puller, but I wanted to check if something better already exist on the market (could not find anything on the internet).

Inside stator diameters vary from 4 inch to 7 inch.

Thank you.

Charles

 

[stardelta]

Why do you need to remove the stator from the outer casing? If it is to be rewound there is no need if it is open at both ends. If the risk of damage is not a concern simply break the casing open or split it with a chisel but generaly mass produced stators of the size you mention are not designed with stator removal in mind and there is no easy or foolproof way of doing it with out the risk of damage. The exception to this is the "Pot Stator" type. Typical examples are small coolant pumps as found on machine tools, submersible pumps made by Flygt and ABS and the old Worthington Simpson monobloc design. The way to remove these is to suspend the casing with the open end down, either from a crane or resting in the open jaws of a vice, then quickly apply lots of heat. The idea being that the casing expands and the stator drops out without damage! Especially easy if the casing is made of aluminium. Sometimes tapping with mallets on opposite sides will help to free them off. Smaller ones rely just on an interference fit but larger ones may have grub screws or bolts to hold them in. Some use roll-pins which can be machined out but if its welded in you are in trouble. I have got really tight ones out in the past by fixing the casing to the floor, digging the hooks of an overhead crane into the winding, applying lots of quickheat to the casing then pressing the up button. Its risky but usualy never fails.

 

[ccjersey]

The ones I need to get out are in Copeland semihermetic compressors. Would like to have a couple rewound and the motor shop is willing IF the stators are pulled first. I heard about heating the cast iron housing while it was suspended from the stator, but no luck so far. I am going to have to build something as well. The challenge is that the casing is a blind ended cylinder with a protrusion around the shaft bearing, so getting a grip on the stator is the problem.

Jim

 

[itsmoked]

What about dry ice or liquid nitrogen. Makes for relatively cheap, easily applied, waaay cold. Dry ice could be more selectively applied. It could even be applied with case heating.

Do watch your ventilation using either of them.

 

[stardelta]

It sounds to me like the repair co dont want the hassle of removing the stator or are not confident about doing it in case the casing gets damaged. Semi-Hermatics are always very tight in the casing because being pressurised and gas tight, grubscrews or bolts cannot be used and therefore they rely just on interference to hold the stator in. The secret is a LOT of heat applied very quickly, we use an oxy-propane setup for quick heating, its much more effective than oxy-act`. You may be able to use a 3 legged puller with the toes turned outwards and dig them into the winding at the bottom of the case but I doubt very much the stator will draw out without heat and without distorting the lamination pack at the same time. I always make a point of informing customers of the difficulties this type of job presents and make them aware that parts could be damaged. The usual answer back is Have a go, its scrap either way. In short there is no easy method or answer but its by no means impossible. You could try another repair co, generaly the bigger they are, the more well equiped and experienced they are. Suggest to them the trick I mentioned earlier about using an overhead crane to pull the stator out. I have found it never fails if you can set it up correctly and safely.
Another consideration relating to semi-hermatic rewinds is the fact that the properties of the refridgerent gas used in the system can be affected by the chemicals given off from the insulation materials used in the winding if it overheats and burns out.