Service HotlineDallasHexagon head bolts are divided into two types: outer hexagon bolts and inner hexagon screws. According to the force mode of the connection, there are ordinary ones and those with reaming holes. The bolts used for reaming holes should be matched with the size of the holes and are used when receiving lateral force. According to the shape of the head, there are hexagonal head and round head. , square head, countersunk head, etc. Generally, the countersunk head is used in places where the surface is smooth and no protrusions are required after connection, because the countersunk head can be screwed into the part. The round head can also be screwed into the part. The tightening force of the square head can be Larger, but larger in size. Hexagons are the most commonly used. In addition, in order to meet the needs of locking after installation, there are holes in the head and holes in the rod. These holes can prevent the bolts from loosening when they are subjected to vibration.
Nuts cooperate with screws to achieve the fixing and connection of components. SMD nuts are generally used in the circuit board industry to fix electronic components. That is, the chip nut is soldered on the circuit board by solder, and the electronic components are fixed by turning the screw. However, when the current chip nut is soldered on the circuit board, there may be uneven soldering, which makes the soldering untidy. At the same time, during soldering, the excess solder overflows from the periphery of the nut, which affects the appearance and may affect its appearance. electrical properties. In addition, the nut is only welded with the circuit board on one end face, and its firmness and reliability after welding are low.
The electroplating of cross recessed screws generally refers to the electroplating of iron cross recessed screws. Stainless steel cross recessed screws are rarely electroplated. The electroplating colors of cross recessed screws are divided into environmental protection and non-environmental protection. Environmental protection blue zinc, environmental protection color zinc, environmental protection black zinc, environmental protection white nickel, etc., non-environmental protection includes white nickel, white zinc, color zinc, black zinc, black nickel, black cladding, blue zinc.
Material 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.
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