To manufacture pseudo spiral plates easily and inexpensively by means of a simple device structure.

The pseudo spiral plate is formed out of single plates 13 having an inner edge 14 and an outer edge 15 concentric with each other and having a cut line 16 extending tangentially from the inner edge 14 to the outer edge 15. The single plates 13 are each bent at a predetermined angle along at least one bending line 17 extending tangentially from the inner edge 14 with a predetermined angle α to the cut line 16, into a bent plate. The cut lines 16 of the bent plates are then connected one to the next.