Bicycle Mechanics - Rear hub - broken??

Hi this is my first post i was wondering if anyone can help. I have a mountain bike and the wheel rubs against the frame when i pedal near the crank. the original axle snapped so i put in another thinking that was the solution however that too bent. Has this happened to anyone else, and will i have to buy a new hub? any help will be appreciated thanks, dean.

Before I invested any more money, I'd be analyzing why you are breaking and bending axles. What kind of rear hub are you using now? Does it have a cassette or spin-on freewheel?

Are you doing big stunts on a poor quality wannabe bike?

Offset wheels may be due to the axle not being correctly mounted in the frame (esp with axle slots/dropouts that are horizontal).
You may have a warped wheel, in which case the spokes would need to be adjusted. This is simple to do, but difficult to do well, kind of like tuning a violin.

If you do have a bent axle, note that there are some really low grade replacement axles around. Beter steel alloys (like chromalloy) are much stronger than the low-end versions.

When you replace the axle, are you assembling all the cones and bearings and locknuts correctly?

i have replaced the hub bearings, the axle and the cones inside the hub, and it bent once again what a waste of £10. It's a cassette type disc hub, the rim and hub seem to be true and so does the disc it really baffles me. It only rubs when pressure is applied to the pedals. if this is something obvious please tell me i think i have done everything right it was spinning fine utill i put it on the frame. Also another wheel worked perfectly fine...

That being the case, I think that I'd turn my attention to the bike frame.

My concern would be if the rear dropouts were parallel. Bike shops have a gauge to check this. It looks like two flat mushrooms that bolt to the dropouts in place of the rear axle. The two mushrooms screw close together to make it easy to spot any out-of-alignment. The gauge also has some longish handles that protrude out each side to serve as levers to coax the dropouts back into alignment.

If you are sure it is adjusted right and the wheel is true, look for a cracked frame. If you are doing stuff that will quickly break the axle in a freehub (kinda rare) you might have done somehting that would break the frame.

A true wheel that is tensioned loose will also move enough, as much a 5-6mm, to rub.