Abstract: A method and apparatus for forming an electric resistance heating coil of desired resistance that involves forming a straight helical coil and centering the formed coil for transfer to a first folding station for holding the straight helical coil into a U-shaped helical coil.

Abstract: A jig for use in manufacturing header assemblies from pipe and tubing. The jig assures the proper orientation and alignment of components during fit up and joining of component parts into a complete header assembly. In addition, the jig is configured to direct a flow of a purge gas that blankets the interior surfaces of the header assembly during a joining process such as soldering, brazing or welding and thus prevents oxidation of those surfaces.

Abstract: A method and machine for forming internal enhancement ribs in heat exchanger pipe or tubing comprises a mandrel which is supported within the tubing and a plurality of opposed rotary dies which have their axes perpendicular to the tube axis so that they rotate in the direction parallel to the tube axis. The rotary dies have a circumferential contact portion that has a concave arcuate profile. In one embodiment, the circumferential surface is scalloped with a succession of axially raised portions. In another embodiment, the rotary die carries a plurality of circumferential rollers.

Abstract: A coiled resistance element is connected to an insulator block by sequentially locating and holding the coil in place; camming the coil such that two adjacent coils are forced together and the coils on either side are forced away so as to form two gaps or openings; and, inserting the arms of an insulator block into the two gaps so as to force the two adjacent coils into the cross bar portion of a T-slot formed in the connector block. Upon removing the camming forces from the coil, the two adjacent coils will be separated and located in the cross bar portion of the T-slot to thereby secure the coil and insulator together.

Abstract: A U-shaped coil is place on the fixture of the present invention and is folded such that each arm of the U is made into a U. The folded coil is then placed upon the insulators of a tree or rack through further movement of the fixture.

Abstract: A coiled resistance element is connected to an insulator block by sequentially locating and holding the coil in place; camming the coil such that two adjacent coils are forced together and the coils on either side are forced away so as to form two gaps or openings; and, inserting the arms of an insulator block into the two gaps so as to force the two adjacent coils into the cross bar portion of a T-slot formed in the connector block. Upon removing the camming forces from the coil, the two adjacent coils will be separated and located in the cross bar portion of the T-slot to thereby secure the coil and insulator together.

Abstract: A slit fin heat exchanger is formed by wrapping slit fin tubing into a flat coil having two spaced rows of tubing. The flat coil is located on mandrels which are rotatable about spaced parallel axes with the mandrels and axes initially being in the same plane. The mandrels are rotated about their axes in opposite directions which shifts the plane in which the coil is located. The shifting of the plane of the coil moves a portion of a first row of the coil into contact with a planar portion of a platen and the second row of the coil into a nesting relationship with the portion of the first row which is in contact with the planar portion of the platen. Continued rotation of the mandrels causes folding of the portions of the coil which extends the area of nesting. The folding takes place through up to 120.degree. and the ends of the first row of the coil contacts a portion of the platen causing the formation of a knob at the end of each coil.

Abstract: A slit fin heat exchanger is formed by wrapping slit fin tubing into a flat coil having two spaced rows of tubing. The flat coil is located on mandrels which are rotatable about spaced parallel axes with the mandrels and axes initially being in the same plane. The mandrels are rotated about their axes in opposite directions which shifts the plane in which the coil is located. The shifting of the plane of the coil moves a portion of a first row of the coil into contact with a planar portion of a platen and the second row of the coil into a nesting relationship with the portion of the first row which is in contact with the planar portion of the platen. Continued rotation of the mandrels causes folding of the portions of the coil which extends the area of nesting. The folding takes place through up to 120.degree. and the ends of the first row of the coil contacts a portion of the platen causing the formation of a knob at the end of each coil.

Abstract: A slit fin heat exchanger is formed by wrapping slit fin tubing into a flat coil having two spaced rows of tubing. The flat coil is located on mandrels which are rotatable about spaced parallel axes with the mandrels and axes initially being in the same plane. The mandrels are rotated about their axes in opposite directions which shifts the plane in which the coil is located. The shifting of the plane of the coil moves a portion of a first row of the coil into contact with a planar portion of a platen and the second row of the coil into a nesting relationship with the portion of the first row which is in contact with the planar portion of the platen. Continued rotation of the mandrels causes folding of the portions of the coil which extends the area of nesting. The folding takes place through up to 120.degree. and the ends of the first row of the coil contacts a portion of the platen causing the formation of a knob at the end of each coil.

Abstract: A slit fin heat exchanger is formed by wrapping slit fin tubing into a flat coil having two spaced rows of tubing. The flat coil is located on mandrels which are rotatable about spaced parallel axes with the mandrels and axes initially being in the same plane. A piece of expanded metal is placed between the two rows. The mandrels are rotated about their axes in opposite directions which shifts the plane in which the coil is located. The shifting of the plane of the coil moves a portion of a first row of the coil into contact with a planar portion of a platen and the second row of the coil into a nesting relationship with the portion of the first row which is in contact with the planar portion of the platen and the piece of expanded metal. Continued rotation of the mandrels causes folding of the portions of the coil which extends the area of nesting. The folding takes place through up to 120.degree.

Abstract: A slit fin heat exchanger is formed by wrapping slit fin tubing around a pair of mandrels having expanded metal cylinders thereon into a flat coil having two spaced rows of tubing. The flat coil containing the expanded metal cylinders is located on mandrels which are rotatable about spaced parallel axes with the mandrels and axes initially being in the same plane. The mandrels are rotated about their axes in opposite directions which shifts the plane in which the coil is located. The shifting of the plane of the coil moves a portion of a first row of the coil into contact with a planar portion of a platen and the second row of the coil into a nesting relationship with the portion of the first row which is in contact with the planar portion of the platen. Continued rotation of the mandrels causes folding of the portions of the coil which extends the area of nesting. The folding takes place through up to 120.degree.

Abstract: A slit fin heat exchanger is formed by wrapping slit fin tubing into a flat coil having two spaced rows of tubing. The flat coil is located on mandrels which are rotatable about spaced parallel axes with the mandrels and axes initially being in the same plane. A piece of expanded metal is placed between the two rows. The mandrels are rotated about their axes in opposite directions which shifts the plane in which the coil is located. The shifting of the plane of the coil moves a portion of a first row of the coil into contact with a planar portion of a platen and the second row of the coil into a nesting relationship with the portion of the first row which is in contact with the planar portion of the platen and the piece of expanded metal. Continued rotation of the mandrels causes folding of the portions of the coil which extends the area of nesting. The folding takes place through up to 120.degree.

Abstract: A slit fin heat exchanger is formed by wrapping slit fin tubing around a pair of mandrels having expanded metal cylinders thereon into a flat coil having two spaced rows of tubing. The flat coil containing the expanded metal cylinders is located on mandrels which are rotatable about spaced parallel axes with the mandrels and axes initially being in the same plane. The mandrels are rotated about their axes in opposite directions which shifts the plane in which the coil is located. The shifting of the plane of the coil moves a portion of a first row of the coil into contact with a planar portion of a platen and the second row of the coil into a nesting relationship with the portion of the first row which is in contact with the planar portion of the platen. Continued rotation of the mandrels causes folding of the portions of the coil which extends the area of nesting. The folding takes place through up to 120.degree.

Abstract: A wrapped fin heat exchanger is disclosed having variable spacing between adjacent loops forming the heat exchanger. Various embodiments are shown wherein the spacing between adjacent loops of single row and multi-row coils is varied to provide for equal heat transfer per loop of the heat exchanger and to effectively level out the air flow per loop. The various embodiments include varied spacing over a single row coil and multiple row coils having partial second rows and second rows with varied spacing while the first row has fixed spacing.

Abstract: A wrapped fin heat exchanger formed from a continuous length of tubing having a fin wrapped thereabout to provide an enhanced heat transfer surface is disclosed. A cylindrical core portion is formed from loops of tubing and a second cylindrical locking portion is mounted thereabout. The locking portion has bands which extend about and in engagement with the loops of the core portion to secure the heat exchanger in a predetermined configuration. By utilization of the locking portion and the core portion the unwinding of the heat exchanger is prevented and its structural integrity is maintained for subsequent manufacturing operations.