Apparatus and method for assembly of structural profiles and resultant structures
A composite structure has a pair of parallel aluminum extrusions bridged by a polymer cap and defining a U-shape hollow. The hollow is filled with an expandable foam that adheres to and mechanically interdigitates with the extrusions, which have channels for receiving insertion legs of the extrusions and have extensions, which the foam encapsulates. End caps may be used to further delimit the hollow. The caps and the foam have a thermal conductivity less than that of the extrusions, providing a thermal break. An upper cap may be used and may incorporate features to compensate for the foam expansion. Excess foam may be trimmed. A forked tool may be used to hold the extrusions during joining.
1. A composite structure, comprising:
a first extrusion;
a second extrusion disposed adjacent the first extrusion with a space there between, each of the first extrusion and the second extrusion having a channel;
a cap extending between and joining the first extrusion and the second extrusion and defining a three dimensional volume bounded by the first extrusion, the second extrusion and the cap, the cap being made from a material having a thermal conductivity less than that of the first extrusion and the second extrusion; and
a foam fill at least partially filling the volume,
wherein the cap has a pair of insertion legs extending from opposing sides of the cap, each of the pair of insertion legs extending in the same direction,
wherein each of the channels is parallel with one of the pair of insertion legs, and
wherein the channels open toward the cap such that each of the pair of insertion legs insert into one of the channels, the channels having extensions extending into the volume from a bottom surface of the channel distal to an opening of the channel, along a length of the channels, the extensions extending in a direction distal to an insertion leg inserted therein, the extensions extending into the foam and having indentations in a surface thereof within the volume, the foam interdigitating with the indentations.
2. The composite structure of claim 1 , wherein the first extrusion and the second extrusion are parallel and have an aluminum alloy composition, the cap has a polymer composition and the foam has a polymer composition, the foam having a thermal conductivity less than that of the first extrusion and the second extrusion, the foam adhering to the first extrusion and the second extrusion.
3. The composite structure of claim 2 , wherein the composite structure defines a U-shape, with a bottom of the U defined by a web of the cap extending between the pair of insertion legs, a first side of the U-shape defined by the first extrusion and a second side of the U-shape defined by the second extrusion, an area between the first side, the second side and the bottom of the U-shape being a cross-section of the volume receiving the foam fill.
4. The composite structure of claim 3 , further comprising
a pair of end caps bridging the first extrusion, the second extrusion and the cap and perpendicularly thereto, a first end cap of said pair of end caps applied to one end of the first extrusion, the second extrusion and the cap and a second end cap of said pair of endcaps applied to a second end of the first extrusion, the second extrusion and the cap.
5. The composite structure of claim 4 , wherein the first and second extrusions each have a second channel and further comprising a second cap with a pair of spaced insertion legs inserted into the second channels of the first and second extrusions, the second cap covering the foam in the volume.
6. The composite structure of claim 3 , wherein each of the channels have teeth retaining the insertion legs that are inserted therein and wherein the insertion legs have barbs retaining the insertion legs in the channels.
7. The composite structure of claim 3 , further comprising a second cap, the second cap having a web and insertion legs, the channel of each of the first extrusion and the second extrusion being a first channel and each of the first extrusion and the second extrusion having a second open channel facing in a direction opposite to the first channel, insertion legs of the second cap being received in corresponding ones of the second channels, the second cap at least partially covering the foam fill.
8. The composite structure of claim 7 , wherein the foam fill is expanding foam and wherein the foam fill contacts the web of the cap, the web of the second cap, the first end cap and the second end cap.
9. The composite structure of claim 8 , wherein the foam fill displaces the web of at least one of the first cap and the second cap to a displaced configuration.
10. The composite structure of claim 9 , wherein the displaced configuration is flatter than a relaxed state from which the web was displaced by the foam.
11. The composite structure of claim 8 , wherein the web of at least one of the first cap and the second cap has a varying thickness, with the thickness increasing from the edges of the web to the center.
12. The composite structure of claim 8 , wherein the web of at least one of the first cap and the second cap has a double wall with a top wall and a bottom wall and at least one intermediate wall running between the top wall and the bottom wall.
13. The composite structure of claim 8 , wherein the web of at least one of the first cap and the second cap has a fin extending therefrom in a direction distal to the foam fill.
14. The composite structure of claim 1 , wherein the indentations in the extensions are knurling indentations and the foam is expanding foam that expands into the indentations, the foam mechanically keying to the extensions when the foam is in a solid state.
15. The composite structure of claim 1 , wherein the first and second extrusions each have a second channel with a second extension extending toward the first channel.