What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The purpose of Guangdong Yueluo Hardware Industry Co., Ltd. is to overcome the deficiencies in the existing technology and provide a square nut fastener for cable tray installation, which has a simple and reasonable structure, and is extremely convenient and flexible to operate; it does not occupy C-shaped steel after installation. The space at the bottom increases the diversity of installation, and can be applied to square nuts of different thicknesses, and the installation is firm
From the perspective of use: The bolted connection of the main components of the building structure is generally connected by high-strength bolts. Ordinary bolts can be reused, but high-strength bolts cannot be reused. High-strength bolts are generally used for permanent connections. The high-strength bolts are prestressed bolts. The friction type uses a torque wrench to apply the specified prestress, and the pressure type screw off the torx head. Ordinary bolts have poor shear performance and can be used in secondary structural parts. Ordinary bolts just need to be tightened. Ordinary bolts are generally 4.4, 4.8, 5.6 and 8.8. High-strength bolts are generally 8.8 and 10.9, of which 10.9 is mostly. Level 8.8 is the same level as 8.8S. The mechanical properties and calculation methods of ordinary bolts and high-strength bolts are different. The stress of high-strength bolts is firstly by applying a pre-tension force P inside, and then generating frictional resistance on the contact surface between the connected parts to bear the external load, while ordinary bolts directly bear the external load.
At present, the main four kinds of anti-shedding nuts are still prone to falling off. Friction and anti-shedding are in the case of shock, vibration and variable load. At the beginning, the nut will decrease in preload due to relaxation. As the number of vibrations increases, the loss of preload will increase. The force increases slowly, eventually causing the nut to loosen and the threaded connection to fail. The mechanical nut is prevented from falling off by adding a stopper, which makes it inconvenient to disassemble. The riveting and punching prevention is to prevent the separation by welding, bonding, etc. This method can only be disassembled by destroying the bolt pair.
In terms of inner hexagon, there are two versions of the national standard, one is GB70-76, the 76-year version, and the other is GB70-85, the 85-year version, most of which implement the DIN912 standard, so you should pay attention to the difference in actual business operations: GB70 -85 completely coincides with DIN912, so there is no difference in the use of the new standard, mainly the difference between GB70-76 and DIN912: for M8 series hexagonal products, the diameter of the round head of GB70-76 is 12.5MM, It is smaller than 13.27MM of DIN912. For M10 series inner hexagon products, the round head diameter of GB70-76 is 15MM, which is smaller than 16.27 of DIN912. For M12 series inner hexagon, the round head diameter of GB70-76 is 18MM. It is smaller than the opposite side 18.27 of DIN912, and the round head diameter of the inner hexagon GB70-76 of M16 and M20 series is 0.33MM smaller than that of DIN912, which are 24MM and 30MM respectively. DIN912 is 24.33MM and 30.33MM respectively. In addition, the width of the inner hexagon between the old standard and the German standard is different due to different standards. The inner side of GB70-76 is smaller, and it should be paid attention to in business operations.
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