Rondex Oy Ltd.

Veli Pekka Kujanpaa

Juha Varis

Ari Juhani Piispanen

Timo Kassi, Deceased

Timo Savinainen

A process and apparatus for the manufacture of a cooking vessel, such as a frying pan (12) or a kettle from a metal blank. The vessel is manufactured by roll forming techniques by using a lower tool (3) that rotates around its axis (2), the form face (6, 7) of the lower tool being designed so that it corresponds to the outer surface of the thus created vessel, and an upper tool (5) that rotates around its axis (4), the surface (9, 10) of the upper tool having a profile that corresponds to the inner surface formed to the vessel. The blank is placed on the form face of the lower tool and the tools (3, 5) are then made to rotate so that the blank rotates along with the lower tool (3), and the surface of the upper tool (5) is in linear roll contact with the blank, whereby the metal is formed in the slot between the tools, spreading out into the desired form of the vessel. A vertical wall on the lower tool adjacent the blank may prevent the blank from becoming dislocated on the lower tool. First, a pressure sufficient to give the blank substantially the desired form of the cooking vessel is applied. Thereafter, the pressure is reduced to finish the surfaces of the cooking vessel. In the manufacture of the frying pan (12), the blank may be a straight piece of sheet, whereby the rising sides of the pan are formed in the roll forming with the blank spreading radially outwards at its edges. In connection with the forming, the outer and inner surface of the vessel can be provided with patterns consisting of protrusions and/or recesses.

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Lappeenranta, Finland

Veli Pekka Kujanpaa