Carrier Corporation

Ross A Moyer

William E Wright

Kenneth P Gray

John R McManus

Bruce J Poplawski

Daniel P Gaffaney

Dale E Jackson

Michael L McDonough

Gerald F Robertson

John R Duncan

Roderick G Rohrberg

A method for roll embossing an enhancement pattern into a surface of a metal strip. The method is intended for use in manufacturing roll formed seam welded metal tubing having interior or exterior surface enhancements to improve the heat transfer characteristics of the tube. Metal strip produced by use of the method has a weld zone adjacent each edge of the strip that does not have the surface pattern embossed upon it but has been rolled to a thickness less than the initial thickness of the strip feedstock. The amount by which the rolled thickness of the strip in the weld zones is reduced from the initial thickness is such that the portions of the strip in the weld zones undergo the same elongation as the central portion of the strip which receives the roll embossed surface enhancement. In this way no tensile stresses are introduced into the weld zone and it has a uniform and predictable thickness that will ensure a good welded seam during later welding into finished tubing.

Method for roll embossing metal strip

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.

Method and apparatus for internally enhancing heat exchanger tubing

A single-station tube expander apparatus bells and expands the open ends of heat exchanger hairpin tubes in a plate-fin heat exchanger unit. A frame supports belling jaw fingers which close over and the open ends of the tubes so that a belling device can enter the tube ends to urge the tube outward into a profile surface formed in the mating faces of the fingers. Also on the frame are mounted expander jaw fingers which close over tube ends which have been belled previously, and hold the associated hairpin tubes against axial movement while expander rods pass into the associated tube legs to urge the hairpin tube legs outward to contact against the fin plates and tube sheets of the fin pack heat exchanger. The belling fingers and belling device move step by step from one tube to another, and the expander gripping fingers and expander rods follow the belling fingers and belling device.

Single station tension hairpin tube expander

A method of arc welding is disclosed. Specifically, a method of pulsed direct current (DC) arc welding is disclosed wherein special pulses of positive direct current are used to weld together work pieces. The special DC pulses are capable of dissipating difficult to reduce oxides which may be present on the surfaces of the work pieces without using a flux. The method is especially useful for fluxless arc welding of aluminum, particularly thin wall aluminum tubing used in making heat exchangers for air conditioning systems.

Pulsed direct current arc welding

A method and apparatus for slitting ribbon stock for use in making fins for a heat exchanger. A pair of slitter wheels are mounted to co-act on separate shafts. One of the shafts is driven by a motor and the other shaft is driven therefrom. Notched pulleys mounted on each shaft and a double sided belt connects the pulleys to maintain the slitter teeth and respective wheels in registration during rotation. A phase shifting device is further provided to allow for initial alignment of the slitter teeth relative to the pulleys.

Heat exchanger ribbon slitting device and method

A method of arc welding is disclosed. Specifically, a method of pulsed DC arc welding is disclosed wherein the pulse width of the current pulses are modulated to maintain a constant time averaged power flow to the work pieces being welded. This method of arc welding is especially useful with a type of pulsed DC arc welding wherein the ratio of peak current to maintenance current is maintained at a selected high value and the current is cycled in a time duration whereby oxides on the surface of the work pieces are dissipated as the weld is made. When used with this type of pulsed DC arc welding the present method is especially suited for fluxless welding of aluminum work pieces, such as thin wall aluminum tubing used in making heat exchangers for air conditioning systems.

Pulse width modulated pulsed DC arc welding

Method of manufacturing a heat exchanger element with a plurality of helically wound coils. The tubes are wrapped about a forming drum in a parallel abutting relation to each other to form a plurality of helically wound coils. Terminal leads are provided at each end of the coil. Terminal leads at each end of the coils are bent, disposed one inwardly the other so that they are positioned tangent to the same plane, which is perpendicular to the center longitudinal axis of the coils, and then a portion of each terminal lead is cut off and joined to a header.

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LaFayette, NY, United States of America

Ross A Moyer