Abstract: The method and apparatus for forming flanged holes and a resulting plate and tube assembly of the type used in fluid-to-fluid, such as gas-to-gas, liquid-to-liquid and liquid-to-gas, heat exchangers. A depression is formed with the aid of a punch in a plastically deformable metal sheet such as steel, aluminum, copper and the like, while applying controlled counterpressure with the aid of a larger counter-punch so that material displaced from the space between the punches is laid upon the inner bore of a constraining die. Thus the wall of the depression is formed by purely compressive means. The base of the depression may then be removed to provide deep flanges of controlled dimensions free of cracks or splits.

Abstract: The method and apparatus for forming flanged holes and a resulting plate and tube assembly of the type used in fluid-to-fluid, such as gas-to-gas, liquid-to-liquid and liquid-to-gas, heat exchangers. A depression is formed with the aid of a punch in a plastically deformable metal sheet such as steel, aluminum, copper and the like, while applying controlled counterpressure with the aid of a larger counterpunch so that material displaced from the space between the punches is laid upon the inner bore of a constraining die. Thus the wall of the depression is formed by purely compressive means. The base of the depression may then be removed to provide deep flanges of controlled dimensions free of cracks or splits.

Abstract: The method and apparatus for forming flanged holes and a resulting plate and tube assembly of the type used in fluid-to-fluid, such as gas-to-gas, liquid-to-liquid and liquid-to-gas, heat exchangers. A depression is formed with the aid of a punch in a plastically deformable metal sheet such as steel, aluminum, copper and the like, while applying controlled counterpressure with the aid of a larger counterpunch so that material displaced from the space between the punches is laid upon the inner bore of a constraining die. Thus the wall of the depression is formed by purely compressive means. The base of the depression may then be removed to provide deep flanges of controlled dimensions free of cracks or splits.

Abstract: A method for producing steel filaments having a heat treated microstructure is disclosed. The method comprises the steps of providing a steel coil having a carbon content from about 0.30 to about 0.95, percent by weight, scoring the surface of the steel to form a plurality of grooves that delineate continuous longitudinal segments, heat treating the steel to develop an appropriate metallurgical structure, separating the segments into individual filaments by causing the steel to fracture at the grooves, and then passing the filaments through a mechanical straightener.