I am still fighting with the right temperatur. I tryed to print 2 Fischertechnik bricks with a lenght of 9cm. With the temperatur setting of the fan duct i got warping.
The folliwing values were successfull :
Chamber temperature - 150C
Powder surface - 174.6C
Speed - 750mm/s

With lower speed i got aways warping. But with this values it was very hard to get the object free from powder.

After this i tried to print an object that has less big printed areas.

Chamber temperature - 150C
Powder surface - 171.7C
Speed - 450mm/s

It was important to lower the speed. The result was great. Easy to clean and no warping.

I am still searching for the right setting to print an object. I am not shure when big printed areas makes an problem....