Abstract: This invention relates to apparatus for facilitating the construction of a heat exchanger, such as a condenser or evaporator employed in an air conditioning system, wherein exchanger tubes extending through a plate fin assembly are joined together by means of return bend connections or the like. The ends of the tube are provided with an oval shaped bell in which are telescoped the return bends. Diametrically opposed nibs are formed on the outer surface of the return bend connectors near the distal end thereof. The outside diameter over the nibs is slightly larger than the minor inside diameter of the oval bell. The nibs are inserted into the bell aligned along the minor diameter of the opening. The nibs are thus caused to ride in engagement against the wall of the bell to frictionally support the connector in assembly. The joint is then immersed in a molten solder bath whereby solder flows freely into the joint region along the major axis to create a highly reliable joint.

Abstract: Apparatus for bonding the tubular joints of a heat exchanger using an ultrasonic soldering process in which the heat exchanger structure is heated while the joints thereof are immersed within a molten solder bath thereby preventing excessive amounts of heat from being drawn out of the joint region during the bonding process.

Abstract: This invention relates to apparatus for facilitating the construction of a heat exchanger, such as a condenser or evaporator employed in an air conditioning system, wherein exchanger tubes extending through a plate fin assembly are joined together by means of return bend connections or the like. The ends of the tube are provided with an oval shaped bell in which are telescoped the return bends. Diametrically opposed nibs are formed on the outer surface of the return bend connectors near the distal end thereof. The outside diameter over the nibs is slightly larger than the minor inside diameter of the oval bell. The nibs are inserted into the bell aligned along the minor diameter of the opening. The nibs are thus caused to ride in engagement against the wall of the bell to frictionally support the connector in assembly. The joint is then immersed in a molten solder bath whereby solder flows freely into the joint region along the major axis to create a highly reliable joint.

Abstract: An ultrasonic dip soldering process for bonding the tubular joints of a heat exchanger made up of tubular components joined together to form flow circuits within a fan coil. The joints are positioned adjacent to one of the tube sheets of the fan coil structure and the joints preheated by means of a remote heating process. The joints are then immersed in a molten bath of solder and treated to ultrasonic energy while in the bath.

Abstract: A process for heating the tubular joints of a heat exchanger assembly to facilitate the creation of a fluid-tight bond between the tubular elements. The joints are positioned adjacent to one or both of the heat exchanger tube sheets and a jet of flammable gas directed into the joint region generally perpendicular to the plane of the tube sheet. The velocity of the gas stream directed at the sheet is high enough to prevent the gas from mixing with ambient air and thus being ignited. Upon impacting the tube sheet, the gas stream is redirected along the sheet, reducing its speed and mixing the gas with surrounding air. A combustible blanket is thus established about the tube joints which is ignited to produce controlled heating thereof.