Dryer making very loud noise after few minutes?

ALWAYS UNPLUG YOUR DRYER BEFORE STARTING ANY REPAIRS
Your problem sounds like drum rollers have flat spots on them or in need of lubrication, or maybe your drum belt has slipped off of the idler arm pulley.

Note: This method works with most front loading machines.

Remove the electrical console that holds the timer switch, start switch, etc. from the top of the dryer if you have to.
Note: Some tops hinge and tilt backwards so they do not have to be removed and the electrical console with stay with the lid.
Also remove the lint filter and the screws holding the lint filter housing in place.
Be REAL CAREFUL not to knock any of the wires off of the timer switch. Then remove the top of the dryer.
Remove the front of the dryer by removing two screws located on either side of the top of the dryer housing and unplug the door switch.
This will expose the drum and belt. Remove the drum and belt and this will expose the drum rollers, idler arm pulley and motor.Now is a good time to replace the front felt seal on the drum if it needs to be replaced. Be sure to use a good grade of weatherproof cement on the seal to glue it to the drum, sometimes the glue is furnished with the seal.
Now is also a good time to check the belt to see if it has slipped off of the idler arm pulley and also to check the belt condition for wear.
Be sure to note the route of the belt, this will come in handy when you go to reinstall the belt.
Check your drum rollers for flat spots or wear, if they have flat spots they will make a thumping type of noise or if there is too much wear on them replace them.
If the drum rollers don't have flat spots or wear on them then they probably only need lubrication. Lubricate the shaft of the rollers with a good grade of machine oil such as 3 in One oil, or a light lubricant like Vasoline.
Reassemble the dryer.
Plug back into your electrical receptical.
This should solve your dryer noise problem.