Importance

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Abstract

A method for continuously relieving residual stresses in hot extruded then cold drawn brass sections, particularly leaded yellow brass. In the disclosed method, the residual stress is localized near the surface of the brass section during cold draw by limiting the percentage reduction in cross-sectional area for the section as it passes through a smaller angle cold draw die. This is accomplished by using a cold draw die having a relatively small attack angle which minimizes the stress at the center of the brass section and localizes the residual stress to an area near the surface of the section. The configured extruded, cold drawn rod is mechanically worked by passing it through mechanical benders which are set to alternatively bend the rod out of alignment first relative to a horizontal longitudinal axis and then relative to a vertical longitudinal axis. The mechanical working of the extruded cold drawn section, according to the present invention, relieves residual stress in the requirement for annealing or heat treatment. The final step in the process is to straighten the section by passing it through a series of rollers in a conventional manner. In an alternative embodiment, the method taught by the present invention may be practiced by two in-line straighteners wherein the first straightener is purposely set out of alignment to work the metal rod and reduce residual stress, and the second straightener is set in a normal manner to restraighten the section to a customer's specifications.

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First Claim