Gathering the ends of heat-conducting pipes in heat exchangers

Claim 1

In the manufacture of a heat exchanger, in which a fluid to be preheated is passed in the heat-conducting pipes having oval cross sections and a hot fluid is passed through a gap formed between these oval pipes, thereby causing heat transfer between said fluid in the pipes and said hot fluid in the gap between the pipes, a method of gathering and holding ends of plural heat-conducting pipes characterized in radially distorting the ends of adjacent oval pipes and flattening portions of the ends to form faces by deforming inwardly parallel to longest dimensions of the oval cross sections and forming thereby relatively long faces and deforming outwardly parallel to shortest dimensions of the oval cross sections and forming thereby relatively short outward extended joining faces and gathering these ends and abutting and joining together said joining faces of each pipe with joining faces of other pipes, and surrounding the joined ends with a thermal strain-compensating frame made of the same material as the pipes.

Claim 6

A method of forming a heat exchanger comprising radially outwardly deforming first and second opposite portions of ends of a curvilinear oval tube and transversely radially inwardly deforming second and third opposite portions of the ends, thereby forming rectangular ends, and forming first and second opposite relatively small parallel faces extended outward beyond the curvilinear portion of the oval tube from the first and second portions, and forming from the second and third portions, second and third opposite and elongated faces connecting the relatively short faces, the elongated faces being parallel to each other and being spaced apart a distance less than a diametrical dimension of the curved tube, and surrounding the ends with a thermal strain-compensating frame made of the same material as the tubes.

Claim 7

A method of forming a heat exchanger comprising radially outwardly deforming first and second opposite portions of ends of a curvilinear oval tube and transversely radially inwardly deforming second and third opposite portions of the ends, thereby forming rectangular ends, and forming first and second opposite relatively small parallel faces extended outward beyond the curvilinear portion of the oval tube from the first and second portions, and forming from the second and third portions, second and third opposite and elongated faces connecting the relatively short faces, the elongated faces being parallel to each other and being spaced apart a distance less than a diametrical dimension of the curved tube, and surrounding the ends with a thermal strain-compensating frame made of the same material as the tubes.