Service HotlineMaterial and process requirements The self-tapping locking screw should be made of high-quality carburized steel cold heading, generally no larger than M12. The finished material should be drawn with a high total reduction rate before cold heading, so that the cold heading must be spheroidized. Annealing, in order to enhance the surface hardness and the toughness of the core, most of them are made of medium and low carbon steel. The chemical composition of the material in the standard is only for guidance. The C content is 0.13%~0.37%, the Mn content is 0.64%~1.71%, and the B content can reach 0.005%. The elements of S, P, Mn and Si in the commonly used steel are generally lower than those of the ordinary bolt steel of the same grade. And the surface quality of the material is strictly controlled to reduce deformation resistance and prevent deformation and cracking. Commonly used grades are 20Mn, 15MnB, SWRCH22A, 1022A and medium carbon steel, medium carbon alloy steel SWRCH35K, SCM435, SCR435, etc. Self-tapping locking screws are threads with an arc-shaped triangular cross-section, so the formulation of cold heading and wire rolling processes, as well as the design and manufacture of cold heading dies and special rolling plates are very important. Self-tapping locking screws require a high-hard surface for cutting and extruding capabilities due to the need for self-tapping low carbon steel. At the same time, there must be sufficient core strength and toughness to prevent twisting and breaking during work. The heat treatment process of this type of screw belongs to shallow carburizing. Regardless of whether it is made of low carbon steel or medium carbon or medium carbon alloy steel, its core hardness must be guaranteed to be within the range of 28~38HRC (9.8 grade) 33~39HRC (10.9 grade) and not less than the minimum tensile load of 930MPa (9.8 grade), 1040MPa (grade 10.9), depending on the material, the minimum tempering temperature is 420℃. In order to ensure that the self-tapping locking screw can be smoothly screwed into the prefabricated cylindrical hole, the end of the screw should be hardened by high-frequency quenching to ensure that at least one to three thread teeth are hardened, and the minimum surface hardness is 45HRC.
In some special occasions, both objects need to be riveted and have good waterproof performance. The existing rivets have poor waterproof performance and often have problems such as water seepage.
1. Ordinary outer hexagon - widely used, characterized by relatively large tightening force, the disadvantage is that there must be enough operating space during installation, and adjustable wrench, open-end wrench or glasses wrench can be used during installation, all of the above wrenches require a large amount of space. operating space. 2. Cylindrical head hexagon socket - is the most widely used of all screws, because it has a relatively large tightening force, and can be operated with a hexagon wrench. It is very convenient to install and is used in almost all kinds of structures. The appearance is more beautiful and neat. The disadvantage is that the tightening force is slightly lower than the outer hexagon, and the inner hexagon is easily damaged due to repeated use and cannot be disassembled. 3. Pan head inner hexagon - rarely used mechanically, the mechanical properties are the same as above, mostly used in furniture, the main function is to increase the contact surface with wooden materials and increase the ornamental appearance. 4. Headless inner hexagon - must be used in certain structures, such as the top wire structure that requires a large top-tight force, or where the cylindrical head needs to be hidden. 5. Countersunk head hexagon - mostly used in power machinery, the main function is the same as the inner hexagon. 6. Nylon lock nut - a nylon rubber ring is embedded in the hexagonal surface to prevent the thread from loosening, and it is used on strong power machinery. 7. Flange nuts - mainly play the role of increasing the contact surface with the workpiece, mostly used in pipes, fasteners, some stamping parts and casting parts. 8. Ordinary hex nut - the most widely used and one of the most common fasteners.
In automobiles, wheel nuts are a widely used component. According to the actual use requirements of the wheel nut, there are often spacers on the wheel nut. In this way, the wheel nut and spacer form a wheel nut assembly. However, in the prior art, since the washer is only movably fitted on the wheel nut, when the wheel nut is removed or a large number of wheel nuts are placed, the wheel nut and the washer will be separated. When in use, they need to be assembled one by one, and when they are disassembled or placed again after use, they need to be assembled again, which not only increases the unnecessary workload, but also affects the use effect of the wheel nut in actual use.
Generally speaking, combination screws are widely used in electrical, electric, mechanical, electronic, household appliances, furniture, ships and so on. But the above said that different combination screws have different functions. For example, Phillips pan head combination screws are generally used in small electronic products. Larger cross hexagon combination screws are used in larger electrical products, such as frequency converters, and some larger frequency converters use many cross hexagon combination screws. Hit the inverter case. To loosen the tightening effect. For example, two combination screws with flower teeth, which are used on the inverter, are used to break the paint, so that all the two combination screws on the surface of the casing are powered on. There is also a two-combination screw with a square pressure line, which itself is a two-combination screw with a pan head screw and a square pad. It is generally used on the surface of the terminal block. The function is for wiring and for crimping.
We have many years of experience in the production and sales of screws, nuts, flat washers, etc. The main products are: machine wire KM screws, large quantities of nuts, cross hexagon bolts, Q863 stainless steel nuts and other products, we can provide you with suitable tightening piece solution.
