Pack of laminations and forming projections and depressions

(19)

(11)

EP 0 304 343 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	08.11.1989 Bulletin 1989/45

(43)	Date of publication A2:
	22.02.1989 Bulletin 1989/08

(21)	Application number: 88309499.7

(22)	Date of filing: 11.10.1988

(51)	International Patent Classification (IPC)⁴: H01F 27/26, H01F 27/24, H01F 41/02, B21D 28/10

(84)	Designated Contracting States:
	AT BE CH DE ES FR GR IT LI LU NL SE

(71)	Applicant: LINTON AND HIRST LIMITED
	Swindon Wiltshire SN 3 4RN (GB)

(72)	Inventors:
	French, William George Swindon Wiltshire (GB) Webb, Charles Harold Bilston West Midlands (GB)

(74)	Representative: Beresford, Keith Denis Lewis et al
	BERESFORD & Co. 2-5 Warwick Court High Holborn London WC1R 5DJ London WC1R 5DJ (GB)

(56)

References cited: :

(54)	Pack of laminations and forming projections and depressions

(57) In one embodiment, the pack is torsionally flexible. Pack of laminations comprises laminations which are connected one to another by only a single connection. The single connection is provided by a projection (4) which projects into a depression (3). The projection (4) has a height which is greater than 50% of the thickness of the lamination and the depression (3) has a depth which is greater than 50% of the thickness of the lamination. The depression (3) and projection (4) are produced by a projection punch (13) which cooperates with a die (14). The die has a lip which is either radiussed (r) or conical (C) and the punch (13) causes the metal of the lamination to be extruded past the lip into the die (14) whilst the depression (3) is being formed. The radiussed or conical lip allows the height of the projection and the depth of the depression to be greater than the normal 50% shear stress fracture depth/height.

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