What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The pressure riveting nut, also known as the self-tightening nut, is a kind of nut applied to thin plates or sheet metal parts. To facilitate the installation of other parts on the printed circuit board. The conventional process is to design prefabricated holes on the printed circuit board in advance, and squeeze the rivet nut into the board through pressure, so that the periphery of the hole is plastically deformed, so that the rivet nut is firmly fixed on the circuit board. In important positions, the use environment of pressure riveting nuts is relatively harsh. In display products, due to space constraints, pressure riveting screws are used a lot. The riveting quality of pressure riveting screws has a direct impact on the reliability of the system. The riveting process is correct. The key technology of using rivet nuts.
At present, during assembly of many pin installation mechanisms, the pins need to be installed into the holes or arranged in an orderly manner, and there are many problems in this assembly method. First of all, during assembly, if the hole diameter of the hole product is large, when the pin enters the hole of the hole product, part of the pin entering the hole of the hole product is not fixed, which often leads to slight deviation. In addition, this assembly method is usually only suitable for parts with large apertures and small depths, and when installing multiple pins, it is impossible to automatically install all pins in place due to space constraints. Special tools need to be made for installation operations, and it is easy to cause pins. damage.
Now people often use spring washers to lock nuts and bolts, spring washers, generally stainless steel and carbon steel non-closed spiral washers, under the nut, above the flat washer, increase the friction between the nut and the bolt, used to prevent The loosening of the nut plays a role in preventing vibration and loosening, but it is often due to a radial external tension, which is caused by the tightening axial force generated by the tightening torque, and the phenomenon of open ring expansion occurs, and the hydrogen embrittlement of the spring washer often occurs. The pressure is unevenly applied to the flat washer through the spring washer, and the friction coefficient between the spring washer and the nut and the flat washer is small, resulting in vibration, rotation and relaxation.
Due to its convenient operation, quick-release screws are widely used in aviation recording equipment, such as the operation panel on the central console of the aircraft, the upper operation panel, etc. However, the assembly of quick-release screws needs to be assembled in sequence. Springs and quick-release screw rods, usually the quick-release screw crimping tools provided by external suppliers can only crimp some small-sized quick-release screws, or custom-made quick-release screw crimping tools for a certain product, time and cost are very high, so it is necessary to design a quick-release screw assembly device for general aviation airborne equipment.
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