2008

Tool for Inspecting Alignment of Twinaxial Connectors

Misalignment can be detected before damage is done.

A proposed tool would be used to inspect alignments of mating twinaxial-connector assemblies on interconnecting wiring harnesses. More specifically, the tool would be used to inspect the alignment of each contact pin of each connector on one assembly with the corresponding socket in the corresponding connector on the other assembly. It is necessary to inspect the alignment because if mating of the assemblies is attempted when any pin/socket pair is misaligned beyond tolerance, the connection will not be completed and the dielectric material in the socket will be damaged (see Figure 1).

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Figure 1. The Dielectric Material Near Sockets is damaged in two of the connectors shown here, because of an attempt to mate them with connectors containing pins that were misaligned with the sockets.

Although the basic principle of the tool is applicable to almost any type of mating connector assemblies, the specific geometry of the tool must match the pin-and-socket geometry of the specific mating assemblies to be inspected. In the original application for which the tool was conceived, each of the mating assemblies contains eight twinaxial connectors; the pin diameter is 0.014 in. (≈0.35 mm), and the maximum allowable pin/ socket misalignment is 0.007 in. (≈0.18 mm). Incomplete connections can result in loss of flight data within the functional path to the space-shuttle crew cockpit displays.

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Figure 2. The Inspection Tool would contain a reticle sized and shaped specifically for the connector assembly to be inspected. The tool would be fit onto the connector assembly. Misalignments would be readily apparent as deviations of pin or socket locations within circles.

The tool (see Figure 2) would consist mainly of a transparent disk with alignment clocking tabs that can be fitted onto either connector assembly. Sets of circles or equivalent reference markings are affixed to the face of the tool, located at the desired positions of the mating contact pairs. An inspector would simply fit the tool onto a connector assembly, engaging the clocking tabs until the tool fits tightly. The inspector would then align one set of circles positioning a line of sight perpendicular to one contact within the connector assembly. Mis alignments would be evidenced by the tip of a pin contact straying past the inner edge of the circle. Socket contact misalignments would be evidenced by a crescent-shaped portion of the white dielectric appearing within the circle. The tool could include a variable magnifier plus an illuminator that could be configured so as not to cast shadows.

This work was done by Christopher R. Smith of United Space Alliance for Johnson Space Center. For further information, contact the Johnson Commercial Technology Office at (281) 483-3809.
MSC-23757