Tham khảo tài liệu 'asm metals handbook - desk edition (asm_ 1998) episode 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Cold Finishing Pipe in suitable sizes and most products classified as tubing both seamless and welded may be cold finished. The process may be used to increase or decrease the diameter to produce shapes other than round to produce a smoother surface or closer dimensional tolerances or to modify mechanical properties. The process most commonly used is cold drawing in which the descaled hot-worked tube is plastically deformed by drawing it through a die and over a mandrel mandrel drawing to work both exterior and interior surfaces. Cold drawing through the die only without a mandrel is called sink drawing or sinking. Tube Reducing and Swaging. In tube reducing by rotorolling or pilgering and in swaging a reducing die works the tube hollow over a mandrel swaging may however be done without a mandrel. The commercial importance of tube reducing is first that very heavy reductions up to 85 can be applied to mill length tubes and second that the process can be applied to the refractory alloys that are difficult to cold draw because of high power requirements. Cold Finishing. Tubular products of circular cross section may be cold finished on the outside by turning grinding or polishing or by any combination of these processes. They may be bored skived or honed on the inside diameter. Because these operations involve stock removal only with negligible plastic deformation there is no enhancement of mechanical properties. Many of the standard specifications involving strength are based on the properties of hot-rolled or cold-worked material. Some high-strength oil country goods are heat treated to achieve the combination of high strength ductility and sulfide stress corrosion cracking resistance required by the intended application. Cold drawing may be employed to improve surface finish and dimensional accuracy and to increase the strength of tubular products. Some customer specifications prescribe strength levels that can best be attained by cold working. Pipe Sizes and .
