MANUFACTURING PLAN FOR WING OF PAV. For the wings of a new personal air vehicle (PAV); skins ands ribs are produced by sheet metal forming process and spars are produced by machining process.

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MANUFACTURING PLAN FOR WING OF PAV

Manufacturing processes are differed according to the fabrication techniques such as sheet metal forming and machining processes. For the wings of a new personal air vehicle (PAV); skins ands ribs are produced by sheet metal forming process and spars are produced by machining process. Finally all produced parts are assembled together to produce final wing structure.    

In addition, since the components that build up ailerons and flaps are very similar to wing structure, manufacturing techniques applied for skins, ribs and spars are also valid for them. Since there should be actuator and hinge fittings to connect ailerons and flaps to wing structure, they are considered in machined parts manufacturing process section.

SKIN MANUFACTURING

Manufacturing process of skins is shown in Figure -1;

Figure-1 [1]

Tools for sheet metal forming Operations;

Stretching Dies, Drill fixtures, drill plates, holding tools

First Cut

Aluminums Raw Materials are cut by shearing machine or hand router to get available sizes for manufacturing with much enough excess portions.    

Heat Treatment

Blanks are then solution heat treated to provide necessary mechanical properties to the parts. Heat treatment operations are done according to the design requirements which are defined by engineering drawings. Heat treatment processes are applied to make parts generally T4, T5 or T6 tempers.

 

Stretch Forming - Skins

On the stretch press, skins are stretch formed and their tooling holes are marked. After removing the skins from stretch presses, the marked tooling holes are drilled for succeeding assembly operations. An example of stretch forming process is shown in Figure – 2.  

Figure – 2 [2]

Skin Routing

Routing operation could be done with two techniques;

The first one is using a routing shell tool which has two parts which have exactly same form of the skin. The skin is then located in between them which is fixed with the tooling holes previously opened after stretching and a hand router is traveled around the tool to shape the skin to its final contour. A photo of a router shell is shown in Figure – 3.

The second technique is using a five axis gantry routing centre with flexible vacuum assisted table. The skin is positioned with the aids of vacuum assisted columns as shown in Figure –4 and tooling holes are used to set the machining coordinate axes.  

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Figure – 3 [3]

Figure - 4 [4]

During routing operation, tack holes are also drilled. Also during routing operation, excess portions like access openings or some pockets are removed from the skin.

Surface Treatment

Surface treatment operations are also defined by the engineering drawings. Some of the surface treatment operations applied are rinsing for cleaning, chromic acid anodizing, primer and coating for corrosion prevention. Primer coating and painting are also called as Chemical Conversion Coating (CCC) which is beneficial for fatigue prevention.

In our case, chromic acid anodizing is ...

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