Since the development of the long march four rocket, the welding of the grade three bottom tank has been carried out by means of welding. This welding method is easy to produce defects such as pores, metal inclusions. Although in the development process has been improved, but compared with the bottom friction stir welding, there is still not a small gap.
In early 2005, the plant began to friction stir welding technology research, and in subsequent years in a new generation of rocket tank shell, short tube longitudinal seam, bottom ring, ring bottom longitudinal seam joint application development breakthrough.
One side is high reliability, green, high degree of automation of friction stir welding technology, on the other side is a mature through the flight test of welding technology, who can not easily change the state of the process technology. However, the test problems, so long march four rocket model developers began to reflect, and in the final determination: the long march four rocket tank welding method must be changed.
At the beginning of 2014, the factory uses the existing equipment and new tooling, in the long march four rocket tank bottom total butt welding in the production of FCL, further realize the friction stir welding production; regular FCL strength test, static tests were first adopted, greatly improved the morale of all personnel type line.
From the beginning of 2005, the research of friction stir welding technology, 2014 March four rocket bottom, tube, short shell longitudinal joints by friction stir welding production of bottom tank was successfully launched, the factory really is "ten years" welding "arrow".
Under pressure to succeed
At the end of January this year, the 149 factory on the friction stir welding fluid oxygen tank FCL to become China's first case smoothly through hydraulic, air tightness test evaluation of products. For this success, the factory's special welding center employees have been difficult to imagine the hard work.
The equipment of the company has successfully developed the friction welding equipment which is the first joint of the launch vehicle in China, and it can be used in the welding of the liquid oxygen tank. Although the friction stir welding technology in the application of multi recognized Rocket Tank in the development, but to the total butt seam welding methods have been used to replace the friction stir welding type, "two" or some not trust.
In order to ensure the high reliability of the test, the model "two total" final decision: liquid oxygen tank "total butt joint seam" welding using welding production.