Offset fin manufacturing method and offset fin manufacturing apparatus

An offset fin manufacturing method for manufacturing offset fins, in each of which lateral surface portions and top surface portions are alternately and continuously formed to have a cross section in a rectangular waveform along a wave continuation direction of the rectangular waveform in each of rows, which are arranged one after another in a crossing direction that crosses the wave continuation direction, while each corresponding lateral surface portion among all of the lateral surface portions of the rows are alternately offset in the wave continuation direction at every predetermined length along the crossing direction, and thereby segments are formed by the lateral surface portions and the top surface portions of the rows in the offset fin, the offset fin manufacturing method comprising:

• a feeding step of feeding a strip plate;
• a connection forming step of forming a connection in the strip plate at every predetermined interval in a feed direction of the strip plate;
• and
• an offset fin forming step of bending a planar plate portion located between corresponding two of the connections in the strip plate to form each of the offset fins such that two of the top surface portions, which are located at an upstream end and a downstream end, respectively, of the offset fin in the feed direction of the strip plate, are respectively and directly connected to the corresponding two of the connections, wherein:
• the offset fin forming step includes forming each of the offset fins such that:
• two of the lateral surface portions are joined to a corresponding one of the two of the top surface portions, which are respectively and directly connected to the corresponding two of the connections, in a corresponding one of the rows, and one of the two of the lateral surface portions joined to the corresponding one of the two of the top surface portions is not offset in the wave continuation direction, and thereby a length of the corresponding one of the two of the top surface portions measured along the wave continuation direction is increased in comparison to at least another one of the top surface portions in the corresponding one of the rows;
• the lateral surface portions, which are other than the two of the lateral surface portions joined to the corresponding one of the two of the top surface portions and are overlapped with the two of the lateral surface portions in a view taken in the wave continuation direction, at least one of the lateral surface portions is located on the same side as that of the one of the two of the lateral surface portions with respect to the corresponding one of the two of the top surface portions and is not offset in the wave continuation direction;
• the one of the two of the lateral surface portions includes a non-offsetting lateral surface portion, which is not offset in the wave continuation direction, and an offsetting lateral surface portion, which is offset in the wave continuation direction and has a length that is measured in the crossing direction and is smaller than the predetermined length;
• and
• the at least one of the lateral surface portions, which is located on the same side as that of the one of the two of the lateral surface portions and is not offset in the wave continuation direction, includes a non-offsetting lateral surface portion, which is not offset in the wave continuation direction, and an offsetting lateral surface portion, which is offset in the wave continuation direction and has a length that is measured in the crossing direction and is smaller than the predetermined length, to correspond with the non-offsetting lateral surface portion and the offsetting lateral surface portion, respectively, of the one of the two of the lateral surface portions.

An offset fin manufacturing apparatus for manufacturing offset fins, in each of which lateral surface portions and top surface portions are alternately and continuously formed to have a cross section in a rectangular waveform along a wave continuation direction of the rectangular waveform in each of rows, which are arranged one after another in a perpendicular direction that is perpendicular to the wave continuation direction, while each corresponding lateral surface portion among all of the lateral surface portions of the rows are alternately offset in the wave continuation direction at every predetermined length along the perpendicular direction, and thereby segments are formed by the lateral surface portions and the top surface portions of the rows in the offset fin, the offset fin manufacturing apparatus comprising:

• a feeding device that feeds a strip plate;
• a connection forming device that forms a connection in the strip plate at every predetermined interval in a feed direction of the strip plate;
• an offset fin forming device that bends a planar plate portion located between corresponding two of the connections in the strip plate to form each of the offset fins such that two of the top surface portions, which are located at an upstream end and a downstream end, respectively, of the offset fin in the feed direction of the strip plate, are respectively and directly connected to the corresponding two of the connections;
• and
• a cutting device that cuts a corresponding one of the connections at every predetermined number of the offset fins, which are connected one after another by the connections, wherein:
• the offset fin forming device forms each of the offset fins such that:
• two of the lateral surface portions are joined to a corresponding one of the two of the top surface portions, which are respectively and directly connected to the corresponding two of the connections, in a corresponding one of the rows, and one of the two of the lateral surface portions joined to the corresponding one of the two of the top surface portions is not offset in the wave continuation direction, and thereby a length of the corresponding one of the two of the top surface portions measured along the wave continuation direction is increased in comparison to at least another one of the top surface portions in the corresponding one of the rows;
• the lateral surface portions, which are other than the two of the lateral surface portions joined to the corresponding one of the two of the top surface portions and are overlapped with the two of the lateral surface portions in a view taken in the wave continuation direction, at least one of the lateral surface portions is located on the same side as that of the one of the two of the lateral surface portions with respect to the corresponding one of the two of the top surface portions and is not offset in the wave continuation direction;
• the one of the two of the lateral surface portions includes a non-offsetting lateral surface portion, which is not offset in the wave continuation direction, and an offsetting lateral surface portion, which is offset in the wave continuation direction and has a length that is measured in the perpendicular direction and is smaller than the predetermined length;
• and
• the at least one of the lateral surface portions, which is located on the same side as that of the one of the two of the lateral surface portions and is not offset in the wave continuation direction, includes a non-offsetting lateral surface portion, which is not offset in the wave continuation direction, and an offsetting lateral surface portion, which is offset in the wave continuation direction and has a length that is measured in the perpendicular direction and is smaller than the predetermined length, to correspond with the non-offsetting lateral surface portion and the offsetting lateral surface portion, respectively, of the one of the two of the lateral surface portions.