The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 17, 1995
Filed:
Jul. 13, 1994
Gerald L Wilson, Wayland, MA (US);
Carrier Corporation, Syracuse, NY (US);
Abstract
A method and apparatus for reforming, by either radially expanding or reducing an electrically conductive tubular workpiece (11). The method of the expansion embodiment comprises the steps of inserting an insulated electrical conductor (21) into the tube; then making up an electrical circuit that includes the portion of the wall of the tube in series or parallel connection with the electrical conductor and a source of electrical power (C and SW), then applying a voltage across the circuit. The current flowing through the conductor and the tube produces a circumferential electromagnetic field between the conductor and the tube. The current in the tube, interacting with the magnetic field, produces a radially directed outward force on the tube. If the force is sufficiently great and of a duration longer than the time required for a sound wave to pass through the tube wall, the tube wall will radially expand and be permanently deformed. The method of the reduction embodiment comprises the additional step of inserting the workpiece in an electrically conductive sleeve (51) and the making up step comprises including the sleeve in the electrical circuit and arranging the workpiece and the conductor in parallel circuit relationship. The respective apparatus of the two embodiments implement the method of the invention. The expansion embodiment of the invention is particularly adapted to the expansion of tubes in plate fin and tube type heat exchangers.