Tube forming methods can be used for efficient transition in the production of tubes having varying thickness. Material used to form consecutive tubes may have the same thickness along a separation plane separating a first discrete section from a second discrete section of the material, and the first discrete section and the second discrete section may each have varying thickness in a feed direction of the material. With such a thickness profile, the first discrete section of the material may be formed into a first cylinder having varying thickness and separated from the second discrete portion as the second discrete section is formed into a second cylinder having varying thickness. In particular, the transition between the first cylinder and the second cylinder may be achieved without scrap and/or interruption, resulting in cost-savings and improvements in production throughput associated with forming tubes having varying thickness.

A method for manufacturing a pipe includes: press-forming a plate member into a U shape; and press-forming the plate member formed into the U shape into an O shape. The pipe includes a pipe body and a tapered part tilted radially inward and protruding from one end of the pipe body. Before the plate member is press-formed into the U shape, a boundary between a portion of the plate member corresponding to the pipe body and a portion of the plate member corresponding to the tapered part is pressed from a surface of the plate member corresponding to an inner peripheral surface of the pipe to bend the portion of the plate member corresponding to the tapered part toward the surface of the plate member corresponding to the inner peripheral surface of the pipe.

A heat transfer tube and a heat exchanger incorporating at least one heat transfer tube are provided. The heat transfer tube and the heat exchanger are optimized for use within an air conditioner (which is configured to operate only in a cooling mode). The heat transfer tube includes a tube body with an interior surface and an exterior surface. The tube body defining an outer diameter (D.sub.o) and a wall thickness (W.sub.T), wherein a ratio (W.sub.T/D.sub.o) the wall thickness (W.sub.T) to the outer diameter (D.sub.o) is between 0.061 and 0.071. The heat transfer tube includes multiple pluralities of adjacent helical fins protruding circumferentially around the interior surface of the tube body at respective helix angles. The multiple pluralities are separated by one or more transition area(s).

A method of manufacturing a filter that includes providing a tube having a cylindrical wall and a hollow interior. The method forms a first indentation within the tube in which a first portion of the of the cylindrical wall concaves into the hollow interior, and forms a second indentation within the tube in which a second portion of the cylindrical wall concaves into the hollow interior. The first and second indentations create 1) a first chamber and a second chamber in the tube that are separated by both indentations and 2) a path within the hollow interior formed between the first and second indentations that fluidly couples both chambers together.

A method for manufacturing a pipe includes: press-forming a plate member into a U shape; and press-forming the plate member formed into the U shape into an O shape. The pipe includes a pipe body and a tapered part tilted radially inward and protruding from one end of the pipe body. Before the plate member is press-formed into the U shape, a boundary between a portion of the plate member corresponding to the pipe body and a portion of the plate member corresponding to the tapered part is pressed from a surface of the plate member corresponding to an inner peripheral surface of the pipe to bend the portion of the plate member corresponding to the tapered part toward the surface of the plate member corresponding to the inner peripheral surface of the pipe.

A heat exchange tube, a heat exchanger, and a manufacturing method for the heat exchange tube are provided. The heat exchange tube includes a tube wall and an outer fin, the tube wall is folded into a tube body, the tube body is provided with an inner fin therein, and the inner fin divides an inner chamber of the tube body into a plurality of flow channels. The outer fin is arranged outside the tube body. The outer fin is folded from a same plate with at least one of the tube wall and the inner fin.

Tube forming methods can be used for efficient transition in the production of tubes having varying thickness. Material used to form consecutive tubes may have the same thickness along a separation plane separating a first discrete section from a second discrete section of the material, and the first discrete section and the second discrete section may each have varying thickness in a feed direction of the material. With such a thickness profile, the first discrete section of the material may be formed into a first cylinder having varying thickness and separated from the second discrete portion as the second discrete section is formed into a second cylinder having varying thickness. In particular, the transition between the first cylinder and the second cylinder may be achieved without scrap and/or interruption, resulting in cost-savings and improvements in production throughput associated with forming tubes having varying thickness.

Tube forming methods can be used for efficient transition in the production of tubes having varying thickness. Material used to form consecutive tubes may have the same thickness along a separation plane separating a first discrete section from a second discrete section of the material, and the first discrete section and the second discrete section may each have varying thickness in a feed direction of the material. With such a thickness profile, the first discrete section of the material may be formed into a first cylinder having varying thickness and separated from the second discrete portion as the second discrete section is formed into a second cylinder having varying thickness. In particular, the transition between the first cylinder and the second cylinder may be achieved without scrap and/or interruption, resulting in cost-savings and improvements in production throughput associated with forming tubes having varying thickness.

A tube for a heat exchanger core bears a micro texture imprinted on an outer surface of the tube. The micro texture having depth of 0.01 mm to 0.03 mm and is thus hardly visible by a naked eye. When the tube is made of cladded metal strip material, the micro texture may have a depth that may be slightly greater than the thickness of the cladding. For folded tubes, an entire strip surface may be covered with the micro texture so that micro texture is present on the outer surface of tube and inside tube. Alternatively, the micro texture may be imprinted after forming the tube so that the micro texture is only present on the outer surface of the tube.

A method of manufacturing a filter that includes providing a tube having a cylindrical wall and a hollow interior. The method forms a first indentation within the tube in which a first portion of the of the cylindrical wall concaves into the hollow interior, and forms a second indentation within the tube in which a second portion of the cylindrical wall concaves into the hollow interior. The first and second indentations create 1) a first chamber and a second chamber in the tube that are separated by both indentations and 2) a path within the hollow interior formed between the first and second indentations that fluidly couples both chambers together.