Method of manufacturing a heat exchange pipe

Claim 1

A method of manufacturing a heat-exchanging pipe comprising the steps of: providing a metal strip; first forming in the metal strip, by rolling with a forming roll having a peripheral edge which moves at a peripheral speed, a plurality of ribs each shaped to have an upstanding face in a direction perpendicular to a direction of rolling and a gently inclined face that descends from an upper end of the upstanding face, this first forming step including the steps of: moving the metal strip at a speed V1 before the metal strip is rolled by the forming roll, the speed V1 being slower than the peripheral speed of the forming roll; moving the metal strip at a speed V2 while the metal strip is being rolled by the forming roll, the speed V2 being substantially equal to the peripheral speed of the forming roll; and moving the metal strip at a speed V3 after the metal strip has been rolled by the forming roll, the speed V3 being faster than the peripheral speed of the forming roll; second forming the strip into a tubular shape along the direction of rolling in such a way that the ribbed surface is on the inside; and permanently joining the edges of the strip to form a pipe.

Claim 2

A method of manufacturing a heat-exchanging pipe comprising the steps of: providing a metal strip; first forming in the metal strip, by rolling with a forming roll having a peripheral edge which moves at a peripheral speed, a plurality of ribs each shaped to have an upstanding face in a direction perpendicular to a direction of rolling and a gently inclined face that descends from an upper end of the upstanding face, this first forming step including the steps of: moving the metal strip at a speed V1 before the metal strip is rolled by the forming roll, the speed V1 being slower than the peripheral speed of the forming roll; moving the metal strip at a speed V2 while the metal strip is being rolled by the forming roll, the speed V2 being substantially equal to the peripheral speed of the forming roll; and moving the metal strip at a speed V3 after the metal strip has been rolled by the forming roll, the speed V3 being faster than the peripheral speed of the forming roll; second forming the strip into a tubular shape along the direction of rolling in such a way that the ribbed surface is on the inside; and permanently joining the edges of the strip to form a pipe.