41 1 are controlled into the open position 41 11 the rotational movement of the pressing devices 41 ideally comes to a standstill when the book gripper 30 1 or 30 2 has deposited a book 1 to be processed on the alignment table 43 1 and is already pivoted back out of the effective range of the pressing plates 41 1 such that the pressing devices 41 can be controlled into their guiding position 41 12 immediately thereafter and the alignment table 43 1 carrying the book 1 can be raised into the aligning position 43 12 after the aligning and post forming processes are completed the forming rail 43 5 is upwardly moved out of the pressing plates 41 1 and the pressing device 41 is controlled into its clamping position 41 13 in which the full surface of the books 1 is already subjected to a certain pressure in addition the heated joint forming rails 42 1 close with increased pressure in order to form the case joints 1 c the rotor movement may begin in the instant in which the forming rail 43 5 is lifted off the fore edge cut 1 b of the book 1 in order to respectively advance the pressing devices 41 by one position during their intermittent rotation the pressing devices 41 pass through a not shown pressing station in which an increased force of pressure can be externally exerted upon the pressing plates 41 while the rotor is at a standstill in order to realize the actual full surface pressing of the books 1 pressure plates 44 2 are accommodated in a machine frame 44.