The non expansion connection technology of titanium pipe fittings is one of the main ways of connecting engine pipelines in the future. It is a new technology introduced from abroad, which has the characteristics of high sealing, light weight, shock resistance and self-locking, no need for insurance, and easy maintenance. It has been widely used in domestic aircraft manufacturing and is a mature and reliable technology. Squeezing the non expanding duct utilizes the self sealing principle that the higher the pressure, the better the sealing, solving the strength sealing problem of high-pressure ducts. However, the quality control of the forming technology without expanding the mouth is the key to ensuring the quality of catheter forming. After extensive testing, titanium rod manufacturers have basically mastered this technology.

Analysis of the difficulties in forming titanium pipe fittings without expansion technology. The principle of extrusion type non expansion conduit forming is to use pre installed equipment to compress the inner wall of the conduit within a certain range using the expansion force of the rubber sleeve, tightly pressing the pipe wall into the two annular grooves of the sleeve, so as to combine them into a whole and achieve the purpose of sealing the conduit and sleeve. The control of groove depth after pre installation and tube bulging is an important factor in ensuring the quality of the combined tube. There are many factors that affect the depth and quality of the pre formed groove of the catheter, mainly including the following three aspects.

(1) The diameter and wall thickness tolerances of domestic conduit raw materials are relatively large, and the wall thickness is uneven, which will affect the fit size clearance of pre installed auxiliary components. In addition, the selection of auxiliary component materials will directly affect the groove depth size.

(2) The forming process and forming pressure also have a significant impact on groove depth.

(3) The rationality of measuring tools and measurement methods are also related to the accuracy of groove depth measurement.