Research Of High-end Fasteners Tightening Process Technology

Fasteners are widely used in all kinds of machinery and equipment. Wherein the high-end fasteners in important areas such as wind power, nuclear power, high-speed rail and aerospace are even more widespread. High-end fasteners refer to the fasteners use of special materials, manufacturing processes and other technical means to obtain higher mechanical properties, thereby overcoming the adverse conditions, which on special machinery and equipment high-end fasteners are applied. Aiming at high-end fasteners tightening control and test theories, by a variety of factors that influence the effect of the tightening assembly analysis, from changing the tightening process variables such as torque-angle distribution to design the test, under the premise to meet the test requirements of fastening technology. A test bench is designed by selection, check and reliability analysis, and ultimately the test feasibility is confirmed and the test program is given.Wherein the fastening processes are commenced from the following three aspects: fastening tools, tightening control methods and tightening sequence. Sensors integration and automation of fastening tools determine the choice of tightening control methods, and tightening control methods in the pursuit of more accurate also requires fastening tools to upgrading to a more advanced level. While the quantity of fastening tools is closely related to the tightening sequence. The more tightening tools, the simpler the tightening sequence, the more the overall cost of the equipment.In fastening testing technology three important items measures are discussed:torque angel-rotation speed, preload and elongation. Torque-angel-rotation speed is a necessary item in the use of torque-angle control method. Preload has a direct impact on the performance of joints, various fastening processes are essentially in order to obtain a more accurate and uniform preload. And a LabVIEW program is developed based on the gasket type pressure sensor to obtain the preload changes. Elongation visually reflects the magnitude of preload. Comprehensive analysis of preload and elongation dispersion can determine advantages and disadvantages of the chosen fastening technology.Firstly, the test bench design analyzes the structure and components of the test piece. According to the needs of the study object and the experiment, the movement and function of the test bench are determined. And according to the usual structure of gantry machine the test bench initial design is completed. Then the key parts of the bench are selected by calculation and check. Consequently, the installation of the test piece and driving, transmission and control system of the test bench are designed. So the test bench from whole to parts and testing program are finished.