What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The technical process of nickel-phosphorus plating for high-strength bolts consists of three parts: The first part is the pre-treatment process, including the precision and appearance inspection of high-strength bolts before plating, manual degreasing, immersion degreasing, pickling, electro-activation and flash nickel plating and other processes; the second part is the electroless nickel plating treatment process; the third part is the post-treatment process, including the processes of hydrogen-displacing heat treatment, polishing and finished product inspection. As follows: Bolt chemical composition inspection → bolt pre-plating accuracy, visual inspection → manual degreasing → visual inspection → immersion degreasing → hot water washing → cold water washing → pickling → cold water washing → electric activation → cold water washing → flash nickel plating → cold water washing → Deionized water washing → Electroless nickel plating → Deionized water washing → Cold water washing → Hydrogen removal → Polishing → Finished product inspection.
With the advancement of technology in various industries, the current structural design of screws has evolved from just simple locking to focusing on work efficiency during the locking process and not destroying the integrity of the objects to be locked. The new cases such as No. 556784 screw improvement and No. 289405 screw that integrates locking, stability, labor-saving, fast and multi-function which were previously designed and approved and published in the Central Taiwan Bulletin are the main representatives of screws. It is clear that It is learned that the two cases not only fully improve the shortcomings of the traditional simple locking screws, but also achieve the purpose of substantial improvement of the screws designed in each case in actual use.
Guangdong Yueluo Hardware Industry Co., Ltd. discloses a countersunk head rivet. The countersunk head rivet includes a nail body and a mandrel. The nail body is tubular, and one end is provided with a nail cap. The mandrel passes through the nail body from the cap end and forms a diameter. For the nail head larger than the internal diameter of the nail, the nail cap is close to the end of the nail head to form a countersunk head. When the countersunk head rivet is in use, the nail body forms a countersunk head structure to the riveted metal piece under the extrusion of the nail head, so that the two riveted metal pieces are firmly riveted without the nail body protruding from the metal piece.
The traditional fixture shown in Figure 2 is composed of a hardened support cylinder and a hardened shear bar, and has a simple structure. The cylindrical pin is loaded into the hardened support cylinder, and the shear test is completed by applying an axial load to the hardened shear bar. Since the standard stipulates that the gap between the loading part and the supporting part does not exceed 0.15mm, in order to ensure the matching of the gap during the shear test of the cylindrical pin, the diameter of the cylindrical pin on the cylinder is generally equal to the theoretical cylindrical pin. In practical application, the cylindrical pin is irregular in size after heat treatment. To realize the shear test, the cylindrical pin must be inserted into the hole with the help of external force, which is difficult to install and clamp and takes a long time. If the double-sided shearing is performed, that is If the cylindrical pins need to be installed on both sides, the time is doubled, and the notch of the cylindrical pins cannot be guaranteed to face upwards.
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