Patent ID: 7728468

Claim:
A lamination, comprising a metal sheet defining a main plane and having at least two sets of plural single-piece spacing strips which have a non-circular cross section in axial and radial directions and project out from the main plane and which have a first edge formed in one piece with the metal sheet and a second free edge in opposition to the first edge intended for touching an adjacent metal sheet of another lamination to thereby define a passageway between the laminations for flow of air to cool the laminations, wherein a first one of the sets of spacing strips is arranged radially inwards on the metal sheet and a second one of the sets of spacing strips is arranged on the metal sheet radially outwards of the first set of spacing strips at a ratio of 1:2 of spacing strips, wherein the spacing strips of the first set of spacing strips are arranged in relation to the spacing strips of the second set of spacing strips such that the first edges of neighboring spacing strips of the first and second spacing strips extend on a common bending line.