Hollow sections

Where practicable, rounded contours and corners are preferable to angles, which are subject to mechanical damage at edges and are difficult to coat evenly Tubular or rolled hollow sections could often advantageously replace 7 or // -sections (Fig. 9.17). 

Hot-dipped tin coatings are difficult to apply outside the thickness range of 8-38 jtm and hot-dipped zinc coatings do not normally greatly exceed 50 m in thickness. Hollow sections and excessively large articles may be impractical to handle by the hot-dipping process and very thin sections may be subject to much distortion. 

Corrosion-inhibited petroleum-based waxes deposited from solvent are finding application in both the automotive and aircraft industries for the supplementary protection of hollow sections of the finished product. These waxes are applied by airless or air-assisted pressure-feed spraying techniques... 

In extrusion of solid rubber sections, the shaped metal plate fitted in the head of the extruder to produce the desired contour in extrusion of hollow tubing the outer circular part which fits over the pin, pencil or nozzle to give the hollow section. 

For pultrusion of hollow cross-sections, cantilever mandrels that are mounted in front of the die (i.e., upstream ) are used. In the transverse direction, the mandrel (which may be heated) is oriented solely by the amount of reinforcement around it. The fact that it is difficult to produce perfectly concentric pipes and hollow sections with well-defined wall thicknesses underscores the significance of predie reinforcement guidance and positioning. 

Minimize the number of hollow sections. Hollow sections add to die cost and make. the die more difficult to clean. 

J.2.3 A section is cut from each of two opposite sides at one end of the length of the square hollow section so that a structure having two flat sided legs surmounted by an 86mm length of intact box results. The end of each flat side is cut at an angle of 60 degrees to the horizontal and welded to the base plate. 

There are many different shaped profiles. These profiles identify many varieties of shapes. Pipes and tubes could be included but the industry has had them classified as a separate category because they represent major and large markets on their own. Profiles normally identify shapes that are noncircular or are not symmetrical. However, there are exceptions where extruded products, such as capillary tubing and rod, are usually called profiles. They can be solid, hollow, or a combination of solid and hollow. Popular shapes include many hollow sections such as in window frame profiles, tapes, edgings, and gaskets as well as a combination of rods with different cross sections structural shapes in the form of Ts, Us, Is, Hs, squares, etc. The product shapes and sizes are as limitless as the number of applications. 

Fusible-core moulding is another IM method which produces hollow-section components. In this process (Figure 4) alloy cores are used to form the complex internal geometry of the moulding these are die-cast from a low... 

For example, consider the assembly shown in Fig. 16-1 (a). It consists of a hollow section through which is passed a loosely fitting bolt with threaded ends. If nuts are screwed on these ends and tightened, the sides of the assembly are compressed and the bolt is placed in tension. The stresses present are residual, inasmuch as there are no external forces acting on the assembly as a whole. Notice also that the tensile stresses in one part of the assembly are balanced by compressive stresses in other parts. This balance of opposing stresses, required by the fact that the assembly as a whole is in equilibrium, is characteristic of all states of residual stress. 

For hollow boards with ribs, the moment of inertia is calculated by elements, adding solid and subtraction hollow sections, each one—if rectangular— is determined by the above formula (7.1). 

Here, from the moment of inertia for the overall section BIfi/12, the moment of inertia of the hollow section (including the ribs) bhVl2 was subtracted, where b = the width of the hollow section, 5.5" - 0.25" - 0.25" = 5.0 in., and h = the depth of... 

PPEIHIPS blends (Gepax , Luranyl , Noryl , Prevex , Verton , Vestoran , Xyron 200). Easy flow and good heat stability make these blends suitable for extrusion of sheets, sections, hollow sections and tubes. 

As noted, the part must be fully supported because of the high forces of FSW. This can be accomplished by having backing support behind the part. The backing can be a fixture itself, or a rib, or some other feature within the part itself. This means that special considerations must be given for open or hollow sections. Open or hollow sections can be welded if the weld is on a rib or other feature in the part, or if a mandrel is built to support the part. 

For a symmetrical beam with a hollow section, it is possible to subtract the I of the hole from that of the outer shape. For the hollow cylindrical beam this gives... 

From this original model a plaster mould is made. The generally consists of a cube of solidified Plaster of Paris that has been formed around the model and then cut in half to leave a hollow section of the required shape. These two halves are then held together with rubber bands or tensioned string etc. Some factories preferred to make their moulds out of clay rather than plaster of Paris as they lasted longer. A plaster mould will only reproduce sharp detail for about fifty casting cycles or so. 

Utilizing bar extrusion, long profiles can be produced (Ostermann 2007 Fritz and Schulze 2008). The variety of producible profile cross sections is immense solid sections of bars and rods and hollow sections with open and closed profiles as well as tubes (Fig. 5). Closed hollow profiles and tubes can be further processed by hydroforming and bending for the manufacturing of profile structures. 

Standard size Square section of200mm, 300mm, 350mm Square section of 200 mm, 250 mm, 300 mm 1, Cylindrical hollow section of external ... 

When a casting is to have a hollow section, a core must be incorporated into the mould. Cores can be made from metal or more commonly from sand, made separately in a core box, and inserted into the mould after the pattern is removed and before the mould is closed. They are located and supported in the mould in a seating formed by the core prints on the pattern. The core must be strong enough to support itself and withstand the flow of molten metal, and in some cases it may be necessary to reinforce it with wires to give added strength. The more complex cores are produced from CO sand. 

BS (1990) Fire Resistant Design-A Guide to Design of Structural Hollow Sections Using BS 5950 Part 8, British Steel, Gorby. 

Parametric study of blind bolted end-plate connection on structural square hollow section... 

Barnett, T, Tizani, W, Nethercot, D. 2000. Blind bolted moment resisting connections to structural hollow sections. Connections in Steel Structures IV, Virginia. 

Silva, L, Neves, L, Gomes, F. Rotational stiffness of rectangular hollow sections composite joints. Journal of Structural Engineering, American Society of Civil Engineering. 129 487-494. 

Molded-in stresses are minimal. The thick but hollow sections provide rigidity and do not create sink or warpage problems. The cycle time is reduced because the thick sections are hollow. As the gas is not mixed with the melt, there is no surface splay, which is typical of low-pressure structural foam molding (1). Gas injection is being used with commodity and engineering resins. 

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