Pipe Cold Extrusion Ring Joint Technical Research

In the field of thin-walled metal tube connection, welding is traditionally used, while its efficiency is low, its labor intensity is high and its assembly is harmful to the working environment, and the welding defects bring about serious influence on the connecting quality of pipes, for example, the strength of the fitting is below that of the pipe, the leak rate of the fittings comes up to one thousandths, and the leakage of some harmful gas seriously imperils human's health. Under these circumstances, the following research is engaged in:Firstly, a new technology of cold-formed tube connection-ringconnection is introduced, and the connecting process and its mechanics performance is researched in this paper. This technology is mainly used in the connection of the same or different material and diameter thin-walled metal tubes. During the connection, the middle joints or the outer tube will have elasto-plastic deformation under the Hoop compression loading exerted by the thrust to the ring, so the tubes are connected and pressurized.Secondly, a mathematic model is established, and the whole connecting process is simulated with the use of ANSYS finite element methods, the connecting force and the stress and strain of the connected fittings are calculated and analyzed during the simulation, and the simulative results are nearly identical with those of the mathematic model.Thirdly, on the basis of the established mathematic model, all kinds of factors on the quality of the connection are analyzed, the seal theory of the connection is put up, and its anti-tensile process and seal performance is simulated with the use of ANSYS finite element methods, and the results are very close to those of the simulation.Fourthly, the parameterized modeling of the joints is obtained on the basis of the good connecting quality, and the optimization design of the joints is made with the size of the ring and pipe as the variation and the seal performance of the joints as the aim function; at the same time, the corresponding double ring connecting device is designed.The result of the connecting experiment indicated the designed ring and device reasonable; and the results of the anti-tensile and seal performance experiments proved that the established mathematic model and the results of the simulation are right. All the results show that the connecting force is lower than other cold-formed connection methods, the strength of the fittings is higher than that of the less strong pipes, and the anti-tensile and leak performance of the fittings is higher than that of other traditional connection methods.The achievements of the design and study about the connection method have further improved the connecting qualities of the pipes and promoted its use and development.