SU1291337A1 - Method of producing welded shell structures - Google Patents

Abstract

The invention relates to the field of welding, in particular, to methods for producing welded cladding structures, mainly thin-walled, from refractory alloys, and can be used in chemical engineering for the manufacture of large cylindrical chemical apparatuses from niobium, molybdenum, tantalum and other refractory metals. The aim of the invention is to improve the quality of the joint to ensure equal strength of the ring and longitudinal seams of the structures. To obtain the shells, cards are welded from sheets that are placed in one direction of the rolled metal, then segments are formed across the rolled products, from which the shells are welded. Improving the quality is achieved due to the orientation of the longitudinal joints of the shells along the rolled sheets, and the ring - across the rolled products. 4 il. s С /)

Description

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The invention relates to welding, in particular, to a method for producing welded cladding structures, preferably thin-walled, of refractory metals, and can be used in chemical engineering.

The aim of the invention is to improve the quality by leveling residual stresses in ring O and longitudinal sheath structures.

FIG. 1 shows a sheet blank (vertical hatching shows the direction of hire); in fig. 2 - stamped segment; in fig. 3 - welded from the Shell; in fig. 4 - welded structures of short shells.

The method is implemented as follows: 20 times.

Collect cards from rolled sheets, placing them in the same direction of hire, weld cards. From the cards, roll the segments across the rolling direction so that the rolling direction coincides with the direction of the forming segment. Then the segments are assembled in a conductor and, in a well-known manner, are welded, for example helium-curved, of longitudinal seams.

In this case, the longitudinal seams will be oriented along the rolling direction. The resulting short frames calibrate, join the mezkdu with themselves, grab them in a known manner and weld the annular joints.

The essence of the method lies in the fact that the longitudinal joints of the shells are oriented along the rolling direction of the sheet blanks, and the annular joints of the shells are transverse to the direction of the rolled products, which allows reducing the residual welding stresses in the longitudinal joints by 35–40%. This is due to the fact that in the process of manufacturing sheet blanks from refractory metals and forming in them rolling texture, the sheet acquires anisotropy. This anisotropy leads to different welding voltages when welding sheets along and across rolled products, despite the fact that 55 the elastic properties of sheets of refractory metals, and in particular niobium, along and across rolled products are almost the same.

Example. According to the proposed method, an experimental shell is made of an NVCH niobium with a thickness of 1 mm with a diameter of 800 mm and a length of 1200 mm. Sheet niobium rolls segments across the rolled products. The segments are assembled in the conductor and the longitudinal seams are welded in the atmosphere-controlled chamber with non-melting tungsten electrode gels in a mode of: 0.28 cm / s: and 16V. The residual welding stresses in the longitudinal straps are 75-80 MPa. Then the shells are joined to each other and helium-arc welding is performed on the given mode of annular joints. The annular joints are oriented across rolled sheets of blanks. The residual welding voltages in the annular joints are 60 MPa.

It was established experimentally that when the seams are reversed (the shell rolls along the rolled metal) relative to the rolled sheet, the residual welding stresses in the longitudinal seams are 140 MPa, and in the ring ones - 40 MPa.

Thus, a positive effect was achieved due to the orientation of the longitudinal points of the shells along the rolled sheets of niobium, and the ring-shaped across the rolled products.

Using the proposed method will create a chemical apparatus for the production of strong nitric acid from niobium. The residual welding voltages at the level of 80-90 MPa allow to ensure the construction, the required operational properties and high reliability.

Claims (1)

Formula invented and A method of manufacturing welded shell structures, predominantly thin-walled, of refractory metals, in which a blank card is assembled from individual rolled sheets, welded, formed from blank cards, segments, welded together by longitudinal seams, to produce sidewall blanks, and then the resulting sidewalls blanks are welded to each other by circular seams, characterized in that, in order to improve quality by leveling the residual welding points 12913374 straps in the ring and longitudinal lines in the same direction along the simplest shell structures, in the process of assembling the cards, the sheets are laid out, and the segments are formed across the direction of hire. kata sheets, and the segments are molded across the direction of hire. (puaZ srig1 CpCfc 3 ffa tjt eSoif u / aS / 7 / 3cr aJ7trHir / u uioS FI.4.4 Editor A.Shandor Compiled by L.Nazarova Tehred D.Oleinik Order 82/16 Circulation 976 Subscription VNIIPI USSR State Committee for Inventions and Discoveries 4/5, Moscow, Zh-35, Raushsk nab. 113035 Production and printing company, Uzhgorod, st. Project, 4 Proofreader S. Shekmar