A method of intermediate frequency resistance diffusion welding of graphite electrodes with controllable deformation

Abstract

The invention discloses a graphite electrode intermediate frequency resistance diffusion welding method with controllable shape variables, and belongs to the technical field of metal material welding.The method comprises the following steps that an anti-deformation protection layer is formed on the periphery of a welding piece by utilizing an anti-deformation cushion block with high-temperature-resistant and high-conductivity, low-loss cushion blocks and flexible conductive paper, and prefabricated pressure clamping and welding assemblies are applied to the upper end and the lower end of a copper anode and a copper cathode correspondingly, and current pulses are applied to a graphite anode and a graphite cathode correspondingly; heat is uniformly diffused to a welding interface and risesto a peak value, and the welding interface and a high-temperature solder are dissolved; and the formed liquid phase achieves joint filling and spreading through capillary force and external extrusionforce to form an interface liquid phase, so that a thick welding piece and a thin welding piece are enabled to be in atomic contact. In conclusion, according to method, the technical problems that a welding material is large in deformation and low in welding quality can be effectively solved.

Description

technical field [0001] The invention belongs to the technical field of metal material welding, and in particular relates to a graphite electrode intermediate frequency resistance diffusion welding method with controllable deformation. Background technique [0002] With the development of high-power wind and hydroelectric generator sets, the structure is compact and stable, and the generator load continues to refresh the world record (currently 5MW in China, 6MW is being developed abroad), which seems to be the development trend of follow-up clean and renewable electric energy. However, Due to its large size and more in the stage of experimental research and development, the conductive copper bars of its ultra-high-power generator windings have fewer supporting processing and forming equipment. In order to ensure the stability of welding quality, the current mainstream method is mostly graphite electrode resistance diffusion welding. [0003] Graphite electrode medium-frequen...

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Problems solved by technology

[0004] However, if the solder used has a high melting point (that is, the design solder melting point is about 80-85% of the base metal melting point), when welding a lap joint with a thin-thickness ratio>3 (assuming the thickness is H, that is: H1:H2>3) , because the heat is gradually transferred from the graphite end to the copper base material, and then from the copper base material to the solder, so there is a serious problem that when the core high melting point solder reaches the melting point and starts to melt, it and the graphite electrode The temperature of the copper base metal in contact is close to the melting point of copper. Since this welding is a pressure test welding, the material sag deformation is generally greater than or equal to about 45%-50% of the thin welding base metal. This is a serious problem for some high-precision application fields. However, if no pressure is applied to ensure no deformation, it will lead to fatal quality defects such as local voids and virtual welds on the welding surface due to different thermal conductivity rates.

This defect is more serious. It not only affects the mechanical bearing capacity of the welding fin part, but also causes discharge arcs to occur in the internal cavity area, resulting in local high temperature melting

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