Stretch forming metal bodies with polymeric internal mandrels

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(11)

EP 0 856 367 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	31.01.2001 Bulletin 2001/05

(43)	Date of publication A2:
	05.08.1998 Bulletin 1998/32

(21)	Application number: 98300707.1

(22)	Date of filing: 30.01.1998

(51)	International Patent Classification (IPC)⁷: B21D 9/01, B21D 25/02

(84)	Designated Contracting States:
	AT BE CH DE DK ES FI FR GB GR IE IT LI LU MC NL PT
	Designated Extension States:
	AL LT LV MK RO SI

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Priority:

31.01.1997 US 36798 P
15.04.1997 US 839616

(71)	Applicant: ALUMINUM COMPANY OF AMERICA
	Alcoa Center, Pennsylvania 15069-0001 (US)

(72)	Inventors:
	Vansumeren, Thomas J. Southfield 48034, Michigan (US) Even, Robert P. Alcoa Center, 15069-0001, Pennsylvania (US)

(74)	Representative: Molyneaux, Martyn William
	c/o Ladas & Parry, Dachauerstrasse 37 80335 München 80335 München (DE)

(54)	Stretch forming metal bodies with polymeric internal mandrels

(57) A hollow metal body is shaped by a process including simultaneous stretching and bending. The body is stretched longitudinally by pulling end portions in opposite directions with sufficient force to exceed an elastic limit and to initiate elongation through plastic deformation. While the body is being stretched longitudinally, it is bent between its end portions transversely of the direction of pulling. Solid polymeric first and second mandrels are inserted into end portions of the body to prevent collapse during bending.

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