16 so that that the cooling mandrel 36 can be introduced into the cylinder 16 where it bears against the cylinder wall 15 in the circumferential direction alternatively or additionally to the configuration according to which the cooling mandrel 36 bears directly against the cylinder wall 15 cooling bristles 38 for example made from copper are provided on the lateral surface of the cooling mandrel 36 these cooling bristles are in contact with the surface of the cylinder wall 15 and in this way dissipate heat from the cylinder wall 15 to the cooling mandrel 36 furthermore cooling passages 40 through which a cooling medium flows and which are used for an active cooling and a dissipation of thermal energy as described above are provided in the cooling mandrel the cooling passages are formed so that they extend in a helically encircling manner particles which do not adhere to the cylinder wall 15 are collected through the use of a collection basin 42 formed on the lower cooling mandrel 36 as shown in fig1 the collection basin 42 is expediently also filled with a cooling medium an additional collection lug 44 guides excess coating material which drops off into the collection basin 42 a cooling medium inlet.