pitch of the folding strip 9 the choice of the production angle u03b2 makes it easy to adjust the operating performance of the rotor seal 7 a a bore 14 is introduced at each folded edge 11 at a predeterminable distance from the longitudinal edge 13 b of the folding strip 9 as an alternative to the round bore 14 that is illustrated it is also possible to select other cutouts of any desired contour the folding strip 9 is folded directly into the annular groove in the seal carrier 5 see fig3 along the folded edges 11 in each case in opposite directions using a calking tool which is denoted by 15 after the folding the bores 14 form a virtually semicircular cutout 8 a that engages in the correspondingly shaped projection 6 of the seal carrier 5 the folding may also take place outside the seal carrier 5 and the rotor seal 7 a formed from the folding strip 9 can then be introduced into the annular groove in the seal carrier 5 in the folded state however it is preferable for the folding to be carried out directly during installation using the calking tool 15 after the rotor seal 7 a has been installed there can be no secondary leaks in the region of the folded edges 11 and consequently a supporting web 16 indicated in fig6 d is not required.