Welding is often used to join metallic structural members to each other. For example, a hollow aluminum extrusion is sometimes welded to an adjacent member in an attempt to create a leak-tight joint that can support high structural loads. However, the material choices for such joints are typically limited to metals. Moreover, the adjacent members must be of the same metal type for efficient welding. High amounts of heat are typically applied, which can distort individual component parts or the entire assembly. Also, it is often necessary to test virtually all welded joints for acceptable leak-down performance, because a number of possible factors—environmental, process related and intrinsic to the parts—can lead to a faulty seal in any individual joint.
Another example is that a slip-fit mechanical joint is prepared by first applying adhesive to one or more parts that are to be slid against each other in assembling the component. However, the sliding action often pushes adhesive out of the bond area which can lead to poor structural integrity. In addition, the sliding action can create voids (e.g., bubbles) in the adhesive layer, and such voids deteriorate the seal quality. For this reason, this type of slip-fit joints often has a sealant separately applied later in the assembly process.
In a first aspect, a method comprises: assembling first and second pieces in a slip-fit joint without applying adhesive or sealant, wherein the first piece covers a portion of the second piece in the slip-fit joint; and injecting adhesive through the first piece until the adhesive fills a gap of the slip-fit joint, wherein the adhesive makes the slip-fit joint air tight without applying the sealant.
Implementations can include any or all of the following features. At least one of the first and second pieces has stand-off ribs that create the gap of the slip-fit joint. The adhesive is injected through an injection port of the first piece until the adhesive is visible in a weep hole of the first piece. The second piece comprises a hollow aluminum extrusion, wherein the first piece comprises an interior lug, and wherein assembling the first and second pieces comprises fitting the hollow aluminum extrusion over the interior lug. The method further comprises mechanically fastening the first and second pieces to each other after assembling them in the slip-fit joint and before injecting the adhesive. The method further comprises fixating the first and second pieces in a fixture before injecting the adhesive.
In a second aspect, an air-tight slip-fit joint consists essentially of: first and second pieces assembled without applying adhesive or sealant, wherein the first piece covers a portion of the second piece in the slip-fit joint; and adhesive injected through the first piece until the adhesive fills a gap of the slip-fit joint, wherein the adhesive makes the slip-fit joint air tight without applying the sealant.
Implementations can include any or all of the following features. At least one of the first and second pieces has stand-off ribs that create the gap of the slip-fit joint. The adhesive is injected through an injection port of the first piece until the adhesive is visible in a weep hole of the first piece. The second piece comprises a hollow aluminum extrusion, wherein the first piece comprises an interior lug, and wherein assembling the first and second pieces comprises fitting the hollow aluminum extrusion over the interior lug. The first and second pieces are mechanically fastened to each other after being assembled in the slip-lit joint and before the adhesive is injected. The first and second pieces are fixated in a fixture before the adhesive is injected.
This document describes systems and techniques for creating an air-tight structurally sound slip-on joint using adhesive, without applying a sealant. In a particular implementation, two pieces are assembled in a slip-fit joint. One of the pieces covers a portion of the other piece. At this point in the assembly, adhesive or sealant is not applied. Next, adhesive is injected through an injection port in the one outward facing piece, for example until the adhesive emerges from a weep hole. When the adhesive has set, the adhesive makes the slip-fit joint air tight without any sealant being applied.
In some implementations, one or more other materials can be used instead of, or in combination with, an aluminum extrusion. For example, and without limitation, a machined piece (e.g., of steel) or a molded piece (e.g., of plastic) can be used.
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A number of implementations have been described as examples. Nevertheless, other implementations are covered by the following claims.