Abstract: In the method of manufacturing a heat exchanger, transverse sectional shapes of heat exchanging tubes can be easily formed into elliptical shapes. The method includes the steps of: piling metallic fins, each of which includes collared through-holes, so as to form tube holes, which are formed by connecting the collared through-holes; piercing heat exchanging tubes, whose transverse sectional shapes are circular shapes, through the tube holes; and inserting expanding bullets, whose transverse sectional shapes are elliptical shapes, into the heat exchanging tubes. The heat exchanging tubes are elliptically expanded to and integrated with the metallic fins.

Abstract: An object of the present invention is to provide a die set, which is capable of removing the influence of heat expansion and the change of the number of the collared holes and improving the accuracy of the collar height. In a die set including an upper die and a lower die wherein a metal plate having a collared hole is provided between the dies to form a flange section at an end of the collar, a flare-punch is provided to the upper die and is capable of vertically moving therein. The flare-punch has a flange forming section for forming the flange section. A biasing member biases the flare-punch toward the lower die. A level pin for defining a lower dead point of the flare-pin is provided to the lower die. The level pin is capable of coming into contact with the flare-punch, which has been in the collar, when the upper die and the lower die are closed.

Abstract: A die-punch machine capable of directly supplying a machining oil to an end section of a punch and to a workpiece to be machined. A first member holds the punch, and a second member is capable of relatively moving to and away from the first member. A die is held by the second member, wherein a front end section of the punch is capable of inserting into the die. A stripper plate provided between the first member and the second member, is connected to the first member, and has a clearance thereto and a through-hole, wherein the clearance is shortened. The front end section of the punch projects from a face of the stripper plate, which is on the second member side, through the through-hole so as to go into the die when the first member and the second member mutually get close. An oil path for introducing machine oil is formed in the stripper plate, one end of the oil path is opened on an inner face of the through-hole.

Abstract: A feeding apparatus for a metal belting has a basic plate being capable of supporting the metal belting, which has a plurality of through-holes in a feeding direction. The basic plate has slit formed in the feeding direction and a plurality of traveling plates are provided beneath and in parallel to the basic plate. The traveling plates are movable in the feeding direction of the metal belting. A driving mechanism for moving the traveling plates in the feeding direction of the metal belting is provided as well as a plurality of feeding pins which are vertically pierced through the traveling plates. Springs bias the feeding pins downward. A plate cam is provided beneath the traveling plates. The plate cam is capable of applying force to upwardly move the feeding pins, against the springs, in a prescribed range.

Abstract: The present invention provides a method of manufacturing fins for heat exchangers, wherein a collared through-hole of a prescribed height can be easily formed while using volatile oils as machining oil, even if the material of the metal plate is thinner and harder than conventionally used.

Abstract: A die set for forms fins of heat exchangers and a manufacturing device using the die set. The die set for manufacturing fins of heat exchangers, comprising a punch and a die for forming a projected section, which is formed along an edge of a hole bored in a metal plate, into a collar with a prescribed height. The die has a hollow section into which the punch is capable of entering and the outer circumferential face of the punch is a tapered face in the form of a truncated cone. The tapered face faces the inner face of the die when the upper end section of the punch proceeds beyond the upper end of the projected section, which is held between the outer circumferential face of the punch and the inner face of the die, and the projected section so held is extruded by reduction of the distance between the outer circumferential face of the punch and the inner face of the die, which hold the projected section therebetween, caused by movement of the tapered face of the punch into the hollow section of the die.