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Friction stud welding is a solid phase welding technique involving a stud or appurtenance being rotated at high speed while being forced against a substrate, generating heat by friction. The metal surfaces reach a temperature at which they flow plastically under pressure, surface impurities are expelled and a forged weld is formed. This technique is rather more costly than arc stud welding and is therefore used for special applications where arc welding may present problems, such as: *welding underwater *welding on live subsea pipelines to attach anodes *welding in explosive environments and zoned areas *welding materials that are difficult to join by fusion welding processes *friction plug welding Portable equipment for friction stud welding is available for use on construction work sites, offshore, underwater and in workshops. These portable units are much lighter and smaller than the large static friction welding machines which are used, for example, in factories to weld engine components such as drive shafts. ==Principle of operation== A portable friction stud welding tool consists of a motor to rotate the stud at high speed and a piston to apply the necessary force to the stud. The equipment may be air or hydraulically powered. A clamping system is also required to hold the tool onto the work piece and to provide reaction to the force on the stud. The clamps used are typically magnetic or vacuum clamps for flat surfaces, chain or claw clamps for pipes and various mechanical clamps for welding onto I beams or other shapes. The weld is made by rotating the stud at high speed and forcing it onto the substrate causing friction which heats the stud tip and substrate surface. Metal at the interface between the stud and the substrate flows plastically under pressure, removing impurities from the metal surfaces, and a solid phase weld is formed. The rotation of the stud is then stopped but the force on the stud is maintained for a few seconds. The maximum temperatures reached during welding are much lower than the melting point of the metals. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Friction stud welding」の詳細全文を読む スポンサード リンク
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