Header of heat exchanger

A cylindrical header of a heat exchanger extending along a longitudinal direction, the cylindrical header comprising:

• a central member extending along the longitudinal direction;
• a front-side member extending along the longitudinal direction on a front side of the central member, the front-side member being configured and arranged to form a front-side space along with the central member;
• and
• a rear-side member extending along the longitudinal direction on a rear side of the central member, the rear-side member being configured and arranged to form a rear-side space along with the central member,
• the central member having
• a first flange covering a front-side-member-first-end part and a rear-side-member-first-end part from outside when viewed in cross-section,
• a second flange covering a front-side-member-second-end part and a rear-side-member-second-end part from outside when viewed in cross-section,
• a first convex part configured and arranged to form along with an inner surface of the first flange a first entry part into which the front-side-member-first-end part enters,
• a second convex part configured and arranged to form along with an inner surface of the second flange a second entry part into which the front-side-member-second-end part enters,
• a third convex part configured and arranged to form along with the inner surface of the first flange a third entry part into which the rear-side-member-first-end part enters, and
• a fourth convex part configured and arranged to form along with the inner surface of the second flange a fourth entry part into which the rear-side-member-second-end part enters,
• the front-side-member-first-end part being one end of the front-side member when viewed in cross-section, the rear-side-member-first-end part being one end of the rear-side member when viewed in cross-section, the front-side-member-second-end part being another end of the front-side member when viewed in cross-section, and the rear-side-member-second-end part being another end of the rear-side member when viewed in cross-section,
• the front-side member being joined to the central member in a state in which the front-side-member-first-end part faces the inner surface of the first flange, and the front-side-member-second-end part faces the inner surface of the second flange, and
• the rear-side member being joined to the central member in a state in which the rear-side-member-first-end part faces an inner surface of the first flange, and the rear-side-member-second-end part faces an inner surface of the second flange.