During the early development stage of balloon deployment systems for missions, nichrome wire cable cutters were often used in place of pyro-actuated cutters. Typically, a nichrome wire is wrapped around a bundle of polymer cables with a low melting point and connected to a relay-actuated electric circuit. The heat from the nichrome reduces the strength of the cable bundle, which quickly breaks under a mechanical load and can thus be used as a release mechanism for a deployment system. However, the use of handmade heated nichrome wire for cutters is not very reliable. Often, the wrapped nichrome wire does not cut through the cable because it either pulls away from its power source or does not stay in contact with the cable being cut. Because nichrome is not readily soldered to copper wire, unreliable mechanical crimps are often made to connect the nichrome to an electric circuit.
A small ceramic tube [0.25-in. wide 0.5-in. long (≈6.4-mm wide 13-mm long)] houses a spiraled nichrome wire that is heated when a cable release action is required. The wire is formed into a spiral coil by wrapping it around a mandrel. It is then laid inside the ceramic tube so that it fits closely to the inner surface of the tube. The ceramic tube provides some thermal and electrical insulation so that most of the heat generated by the wire is directed toward the cable bundle in the center of the spiral. The ceramic tube is cemented into an aluminum block, which holds it in position. The leads of the nichrome wire are attached to screw terminals that connect them to power leads. A bayonet plug mounted at the bottom of the rectangular block connects the power leads to a relay circuit. A thin aluminum shell encloses the entire structure, leaving access points to attach to the bayonet plug and to feed a cable into the cylinder. The access holes for the deployment cable are a smaller diameter than the nichrome coil to prevent the cable from coming in direct contact with the nichrome when loaded.
It uses the same general method of severing a cable with a heated wire as was used previously, but implements it in such a way that it is more reliable and less prone to failure. It creates a mechanism to create repeatability that was nonexistent in the previous method.
This work was done by Michael T. Pauken and Joel M. Steinkraus of Caltech for NASA’s Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Mechanics/Machinery category. NPO-47265
This Brief includes a Technical Support Package (TSP).
Reusable Hot-Wire Cable Cutter
(reference NPO-47265) is currently available for download from the TSP library.
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Overview
The document is a Technical Support Package for the Reusable Hot-Wire Cable Cutter, developed by NASA's Jet Propulsion Laboratory (JPL). It is identified by the NASA Tech Briefs number NPO-47265 and aims to disseminate information about aerospace-related technological advancements that may have broader scientific, commercial, or technological applications.
The Reusable Hot-Wire Cable Cutter is designed to efficiently cut various types of cables, which is particularly useful in aerospace applications where precision and reliability are critical. The document outlines the cutter's features, benefits, and potential uses, emphasizing its innovative design and functionality. The cutter is likely to be employed in scenarios where traditional cutting methods may be less effective or pose safety risks.
The Technical Support Package includes references to comparisons between hot wire and pyro cutters, indicating that the document may provide insights into the advantages of using a hot wire cutter over other cutting technologies. This comparison could highlight aspects such as cutting speed, precision, and safety, which are essential in aerospace operations.
Additionally, the document contains contact information for further inquiries, specifically directing interested parties to the Innovative Technology Assets Management at JPL. This suggests that the package is part of a broader initiative to promote collaboration and technology transfer between NASA and commercial entities or research institutions.
The document also includes a notice regarding the proprietary nature of the information contained within, indicating that it may be subject to export controls and should be handled in compliance with applicable U.S. regulations. This underscores the importance of the technology and the need for careful management of intellectual property.
Overall, the Technical Support Package serves as a comprehensive resource for understanding the Reusable Hot-Wire Cable Cutter's capabilities and potential applications, while also facilitating further exploration and collaboration in the field of aerospace technology. It reflects NASA's commitment to advancing technology and sharing knowledge that can benefit a wider audience beyond its immediate applications.
