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As early as the 1950s, hydraulic expansion forming was already used to produce copper alloy T-shaped tees for use in piping systems and connectors for bicycle frames. The forming pressure used was less than 25 MPa; the parts that could be manufactured had simple shapes and low precision, with the main issue being the poor controllability of the process parameters. The essential difference between modern internal high-pressure forming and the early hydraulic tube expansion process is as follows: ① The forming pressure is high; in industrial production, this pressure generally reaches 400 MPa, and sometimes even 1000 MPa. ②The process parameters are controllable; the internal pressure and axial displacement are subject to computer-based closed-loop control according to a predetermined loading curve. The control accuracy for ultra-high pressures reaches 0.2–0.5 MPa, while the displacement control accuracy reaches 0.05 mm. ③With complex shapes and high precision, these parts can be manufactured as whole units with three-dimensional curved, irregular cross-sections and complex structures; they are primarily used in the production of machine parts for vehicles, aircraft, and other applications. Two areas of technological breakthroughs have contributed to the development of internal high-pressure forming: ① the ultra-high pressure dynamic sealing technology using water as a medium, which enables stable ultra-high pressure sealing at levels above 400 MPa over extended periods under production conditions; ② the ultra-high pressure computerized closed-loop control technology, which not only allows for high-precision tracking of a specified loading curve but also ensures rapid response and feedback from the control system, thereby enabling the processing of a part in approximately 30 seconds.