Riveting

Explosive riveting has been used for over 60 years and was originally designed for rivets where backup space was insufficient for normal processing. Applications include automobile brake shoes, aircraft industry, tanks, and other military vehicles. 

The typical rivet is hollow and filled with explosive which can be detonated either thermally or by an electric charge. A typical sequence of explosive riveting is shown in Fig. 14.4. 

The cost of riveting is lower than that of most other methods of fastening, due to the absence of plain washers, locking washers, nuts or split pins also, the use of self-piercing rivets eliminates the need to predrill holes. Rivets are available in steel, brass, copper and aluminium in a variety of types. The more standard head types used are shown in Fig. 13.12. 

Short-hole tubular rivets. Fig. 13.13(a), have the advantage of a solid rivet with easier clinching. These have a parallel hole and can be used for components of varying thicknesses. 

Double-taper semi-tubular rivets. Fig. 13.13(b), have a taper hole to minimise shank expansion during clinching and are used to join brittle materials. 

Bull-nose semi-tubular rivets. Fig. 13.13(c), are used where maximum strength is required. The rivet shank is intended to expand during the setting operation in order to fill the predrilled hole in the work. This ensures a very strong joint. 

Self-piercing rivets. Fig. 13.13(d), have been specially developed to pierce thicker metal and clinch in the same operation. For metal up to 4.7 mm thick, the self-piercing rivet is made from special steel and is heat-treated to give the required hardness for piercing and ductility for clinching. One use of this type of rivet is automatic riveting in the production of garage doors. 

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In reality, aircraft parts can consist of several stacked layers of material, eonnected by rivets or bolts. To avoid corrosion, the layers are often protected by a special coating, so that there is no electrical connection between the layers. If there is a crack for example in the middle layer, no current will thus flow above or below the defect because of the insulating coating between the layers. There is only the possibility for the current to flow around the crack in the x-y... 

Cracks detection in welds, mounting hardwares, rivets, on blades and vanes, turbine disks, rotors blades, etc. 

Cold or Hot Heading. Rivets or studs can be used in forming permanent mechanical joints. The heading is made with special tools and preferably with the rivet at elevated temperatures. Eormed heads tend to recover part of their original shape if exposed to elevated temperatures, resulting in loose joints. Forming at elevated temperature reduces recovery. 

Transition Joints. Use of explosion-clad transition joints avoids the limitations involved in joining two incompatible materials by bolting or riveting. Many transition joints can be cut from a single large-area flat-plate clad and deflvered to limit the temperature at the bond interface so as to avoid undesirable diffusion. Conventional welding practices may be used for both similar metal welds. 

Explosion-welded constmction has equivalent or better properties than the more compHcated riveted systems. Peripheral benefits include weight savings and perfect electrical grounding. In addition to lower initial installation costs, the welded system requires tittle or no maintenance and, therefore minimizes life-cycle costs. Applications of stmctural transition joints include aluminum superstmctures that are welded to decks of naval vessels and commercial ships as illustrated in Figure 11. 

H. J. Neubetg, J. E. Atheriey, and L. G. Walker, Girdler-Sulfde Process Physical Properties, Atomic Energy of Canada Report AECL-5702, Chalk Rivet Nuclear Laboratories, Chalk Rivet, Ontario, Canada, 1977. 

J. P. Bibler, in TecentDev. Exch. 2, [Proc. Int. Conf Ion Exch. Processes], 2nd, Elsevier, London, held at Westinghouse Savannah Rivet Co., Aiken, S.C., 1990, pp. 121-133. 

Dry ice is used to chill aluminum rivets. These harden rapidly at room temperature, but remain soft if kept cold with dry ice. It has found numerous uses in laboratories, hospitals, and airplanes as a convenient and readily available low temperature coolant. 

A. DiNoto, MrtPlastics, Cross Rivet Press, New York, 1984. 

Two types of localized corrosion are pitting and crevice corrosion. Pitting corrosion occurs on exposed metal surfaces, whereas crevice corrosion occurs within occluded areas on the surfaces of metals such as the areas under rivets or gaskets, or beneath silt or dirt deposits. Crevice corrosion is usually associated with stagnant conditions within the crevices. A common example of pitting corrosion is evident on household storm window frames made from aluminum alloys. 

Application. A company has received a very large shipment of rivets. One product specification required that no more than 2 percent of the rivets have diameters greater than 14.28 mm. Any rivet with a diameter greater than this would be classified as defective. A random sample of 600 was selected and... 

From Moody, Trans. Am. Soc. Mech. Eng., 66, 671-684 (1944) Mech. Eng., 69, 1005-1006 (1947). Additional values of e for various types or conditions of concrete wrought-iron, welded steel, riveted steel, and corrugated-metal pipes are given in Brater and King, Handbook of Hydraulics, 6th ed., McGraw-Hill, New York, 1976, pp. 6-12-6-13. To convert millimeters to feet, multiply hy 3.281 X l0- ... 

Construction Multiwall pasted valve Corrugated box, one-half Flexible hag made of Welded-aluminum tank Welded- or riveted-aluminum Welded-steel Rigid container... 

Area effects in galvanic corrosion are very important. An unfavorable area ratio is a large cathode and a small anode. Corrosion of the anode may be 100 to 1,000 times greater than if the two areas were the same. This is the reason why stainless steels are susceptible to rapid pitting in some environments. Steel rivets in a copper plate will corrode much more severely than a steel plate with copper rivets. 

Fasteners, such as holts and rivets, that are galvanically dissimilar to the materials being fastened should be relatively noble to these materials. 

As discussed in Section 29.2.5, jointing of two different metals (copper being one) causes electrolysis at the joints, leading to corrosion and failure of the joint. To avoid this, it is recommended that the same procedure be adopted as discussed in Section 29.2, and where the electrode and the connecting ground strip are of the same metal, that the joints are riveted or welded with the same metal after making the surface. Soldering is not recommended. 

Series major additive Cu Al -r 4 Cu -r Mg, Si, Mn Strong age-hardening alloy aircraft skins, spars, forgings, rivets. 

A batch of 7000 series aluminium alloy rivets for an aircraft wing was inadvertently over-aged. What steps can be taken to reclaim this batch of rivets ... 

Metal parts are also joined by a range of fasteners rivets, bolts, or tabs. In using them, the stress concentration at the fastener or its hole must be allowed for fracture frequently starts at a fastening point. 

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