A milling robot used to process the internal walls of inaccessible pipelines with a milling robot arm. The milling robot arm supports a milling head that is deflectable via remote control in the direction of the inner wall of the pipe. The milling robot arm stiffens and bends more or less depending on the controlled pressure feed; the eccentric, torsionally rigid, fixed-length core that can only be deflected in one plane provides a high level of torsional rigidity and the outer casing that is stiffened by the controlled internal pressure provides for a high level of stiffness in the longitudinal and bending directions. The milling robot arm can be swiveled all the way around in the inner pipe to be processed with the aid of a supply hose that is rigid in terms of shear or a pneumatically controllable slew ring.