Manufacturing Plan For Wing Of PAV

Manufacturing dishes argon differed according to the fabrication techniques such as sheet metal forming and machining processes. For the wings of a new personal melodic line vehicle (PAV) skins ands ribs atomic number 18 produced by sheet metal forming process and spars ar produced by machining process. Fin onlyy all produced parts are assembled to ticktackher to produce last-place wing construction.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 apparatusd parts manufacturing process section.SKIN MANUFACTURINGManufacturing process of skins is shown in experience -1Figure-1 1Tools for sheet metal forming trading cognitive operationsStretching Dies, Drill fixtures, drill plates, holding toolsFirst CutAluminums Raw Mate rials are cut by shearing machine or hand router to get available sizes for manufacturing with much enough excess portions. agitate TreatmentBlanks are then solution heat treated to reserve 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 snitch parts generally T4, T5 or T6 tempers.Stretch Forming SkinsOn the stretch press, skins are stretch formed and their tooling mints are marked. aft(prenominal) removing the skins from stretch presses, the marked tooling holes are cut for succeeding gather operations. An example of stretch forming process is shown in Figure 2.Figure 2 2Skin RoutingRouting operation could be done with two techniquesThe 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 previou sly opened after stretching and a hand router is traveled around the tool to shape the skin to its terminal 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 nothingness 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.Figure 3 3Figure 4 4During routing operation, tack holes are also drilled. Also during routing operation, excess portions like access openings or some pockets are removed from the skin. develop TreatmentSurface treatment operations are also defined by the engineering drawings. Some of the go on treatment operations applied are rinsing for cleaning, chromic acidulous anodizing, primer and coatinging for corrosion prevention. Primer coating and pic are also called as Chemical Conversion Coating (CCC) which is beneficial for fatigue prevention.In our case, chromic a cid anodizing is applied to 2024 skins for preventing corrosion and paving the way for painting. Before chromic acid anodizing, fine holes should be masked to keep dimensions accurate.A typical anodise process would consist of a solvent wash and/ or an alkaline clean to remove any oils or greases from the surface. followed by a de-oxidiser stage to remove the born(p) oxide film from the surface, followed by chromic acid. This gives you a clean oxide free surface which once anodised will give better adhesion of the anodised layer. There is a water wash off stage between each tank to prevent contamination of the bath solutions. From there you have two choices, spray directly onto te anodise honeycomb structure which will give good paint adhesion, or seal the anodised layer for enhanced corrosion protection but poorer paint adhesion.PaintingFinally, primer, top coat and final paint are applied on the skin.RIB (SHEET METAL) MANUFACTURINGManufacturing process of ribs is shown in Figure 5Figure 5 1Tools for sheet metal forming operationsHydro press forming dies, Drill fixtures, drill plates, holding toolsThe main difference of manufacturing of ribs from skins is hydro press forming process instead of stretch forming.Hydro press FormingAfter heat treatment, blanks become bring in to be formed. In aerospace industry fluid cell forming (hydro press forming) is frequently used for forming operation. That is mostly be driving force of the reality that aircraft parts are manufactured in polished quantities and parts are mostly different in geometry. Therefore it is necessary to manufacture a different tool for every part and that is very costly. Although the machine is quite expensive, to cliff the tooling costs, hydro press forming is preferred since only male dies are necessary to form parts instead of male-female die combination. That is illustrated in the figure. Also some other advantage of hydro press forming is that, on the table of the press machine, sever al tools, with the blanks on them, could be located randomly at once. In one cycle all the parts are formed simultaneously. Also in general press machines are equipped with two tables which bring out it possible to decrease set up time to half. Some photos related with hydro press forming are shown in Figure 6.Figure 6 4SPAR, HINGE, RIB AND FITTING MANUFACTURINGManufacturing process for machined parts, spars, hinges, ribs and fittings is shown inFigure-7Figure 7 1Tools particularised to machining operationsMilling fixturesMachiningIf necessary those parts which will be machined on milling centers, are firstly cut from blocks of raw material to their call for stock sizes. They are mostly skin milled. Skin mill is done to obtain a smooth flat plane to locate the stock on the milling machine table. After skin mill, some holes are drilled on the stock for the sake of transportation and fastening on the machine tables or fixtures. For interlinking milling operations in which there are more than one stages of operations, it is common to use a milling fixture, see Figure -8. other reason for use of milling fixtures is that in aerospace industry manufacturing tolerances are so tight and geometries are mostly very complex that is why it is necessary to provide same machining conditions and set up for every single part. Milling fixtures are tools, on which stock material is located and squeezeed. Their main functionality is that they hold the machined part tightly throughout the machining process which prevents machining defects and dimensional inaccuracies.,Figure 8 4To obtain required dimensional tolerances, some holes require boring. Boring operation removes only a dainty quantity of material therefore before boring operation the hole must be drilled very close to the final dimension of the hole diameter.Dimensional accuracy of the machined parts are generally checked with the utilization of Coordinate Measuring Machines (CMM). These machines are very prec ise such as they are capable of measuring ten thousands of a millimeter in three dimensional spaces. Although they are quite expensive and they need an air conditioned, humidity controlled and shaking isolated chamber, they are the most accurate and flexible measurement equipments.Shot PeeningMachined parts are exposured to shot peening operation. That process is done to remove and minimize the breathing surface cracks on the machined parts. Machined parts are generally bear high amount of repetitive tensial and compressive loads and these repetitive loading is mostly the main cause of fatigue failure. Surface cracks are the mostly affected defects from repeated loading and they tend to grow under these conditions. That is why they must be removed or minimized to prevent them to grow and increase the fatigue durability of the part.Surface treatmentAs explained before both chromic acid anodizing, primer coating and painting are the surface treatment operations applied on the parts to make them resistant to corrosion. Another advantage of these chemical conversion coating processes is that they make the part more durable to the fatigue, since they penetrate to surface cracks, scratches and holes. For instance, pitting is a corrosion type which is more susceptible to such surface defects. Therefore surface treatment processes both provide a protective coating in corrosive environments and they generate a smoother aerodynamic surface, which is a requirement to decrease air drag, especially for the outer surfaces which are in contact with the air during flight.ASSEMBLY OPERATIONSAssembly Operations are shown in Figure 9Figure 9 1Tools for assembly operationsAssembly and sub assembly dances and fixturesAssembly JigIn aerospace fabrication processes, since the parts have very complex geometries and position tolerances are so tight, it necessary to use a fixture to locate parts in their required positions and apply assembly joining operation in these positions wi thout letting them to move. For an air plane wing a single assembly jig could be used for this purpose, see Figure 10.Figure 10 5Spars are located on the jig. They must have a planar smooth contact surface and they must have previously opened tooling holes. Those holes are used to pin the spar on the jig and some clamps are used to fix the spar in its position.Ribs are located. They are installed on the jig with the utilization contacting surface of spar and some other location surfaces and they are pinned from their tooling holes. Clamps are used to fix ribs in their location.Some of the holes are transferred from ribs to spars or the contrary. laughingstock skin is loaded on the jig by the aid of tooling holes on the lugs at each lateral short edge. To wrap the rib spar assembly the skin could be pressed by some belts or some header plates could be used to bring the skin to its required form and clamp it to hold it in its required position.Some of the tack holes on the skin are fastened with clecos, which is a temporary fastener. Pilot holes are drilled to their final sizes and countersinking is applied to locations where countersunk rivets and bolts will be used.After drilling and countersinking is applied parts are separated to remove chips.Before putting parts together again, sealant is applied. Sealant is a viscous chemical isolation material which is a polymer in general (polyurethane, polysulfide, etc). It is applied when it is still in fluid form and it solidifies as a result of chemical reaction which takes place as soon as the sealant is exposed to air. They are used to prevent fluid escape into internal structural components. This leakage could result catastrophic failure since corrosion which erodes material would work against the mechanical strength and stiffness of the structure. For different purposes and for different locations specific types of sealants are applied. For instance polysulfide based sealant is applied to the surfaces where th ere is fuel content. For fuel tanks these polysulfide based sealants are used since they withstand the attack of sulfur compounds that are present in fuel.After sealant application, outer skin is brought to close the wing and it is fastened with blind rivets and bolts since it will only be possible to refer rivet from one side.When riveting and bolting completed the wing is removed from the assembly jig and it is sent to paint shop for the application of top coating and painting. After that manufacturing and assembly operations will be completed.