What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The process of removing iron oxide plate from cold heading steel wire rod is stripping and dephosphorization. There are two methods: mechanical dephosphorization and chemical pickling. Replacing the chemical pickling process of wire rod with mechanical phosphorus removal not only improves productivity, but also reduces environmental pollution. This phosphorus removal process includes bending method (the round wheel with triangular grooves is commonly used to repeatedly bend the wire rod), spray nine method, etc. The phosphorus removal effect is good, but the residual iron and phosphorus cannot be removed (the removal rate of iron oxide scale is 97%) ), especially when the iron oxide scale is very sticky, therefore, mechanical phosphorus removal is affected by iron scale thickness, structure and stress state. Carbon steel wire rods used for low strength fasteners (less than or equal to 6.8) High-strength bolts (greater than or equal to grade 8.8) use wire rods to remove all iron oxide scales after mechanical dephosphorization, and then go through a chemical pickling process for compound dephosphorization. For low carbon steel wire rods, the iron sheets left by mechanical dephosphorization are likely to cause uneven wear of grain draft. When the grain draft hole adheres to the iron sheet when the wire rod rubs against the external temperature, the surface of the wire rod produces longitudinal grain marks. More than 95% are caused by scratches on the surface of the steel wire during the drawing process. Therefore, the mechanical phosphorus removal method is not suitable for high-speed drawing.
The pressure riveting nut is divided into free-cutting steel pressure riveting nut S type, stainless steel pressure riveting nut type CLS, stainless iron pressure riveting nut SP type and copper and aluminum pressure riveting nut CLA type, which should be used in different environments. . Sizes are usually from M2 to M12. There is no unified national standard for rivet nuts, and they are often used in chassis cabinets and sheet metal industries. S series, CLS series, SP series pressure riveting nuts use the internal thread as a simple method to install in precision sheet metal products, and use small and precise nuts for reliable fixing to completely process the side plate of the sheet metal. The nut is inserted into the hole of the metal plate, and the inlay strengthening function is completed by pressure. Application advantages 1. The back of the plate remains completely flat; 2. Small size and precision, suitable for all electronic or precision equipment; 3. High torque resistance; 4. Easy equipment, simple riveting; 5. Standardized serialization can meet various design requirements .
Stainless steel rivet nuts are used on rail passenger cars, highway passenger cars, and ship parking. The main function is the non-structural bearing bolt connection. The main advantage of stainless steel rivet nuts is that there is no operating space on the back of the substrate, and the quality is extremely light. Today, the editor will talk about the selection principles of stainless steel rivet nuts and their uses: 1. The mechanical properties of stainless steel rivet nut materials, especially the strength requirements; Corrosion resistance requirements of materials;
hand screw is a screw with a plastic head, and the user fixes the hand screw by turning the plastic head by hand. At present, a hand-tight screw is disclosed in the market publication number CN202203253U, which includes a plastic head and a screw rod, the plastic head and the screw rod are connected together, and the height of the plastic head is higher than that of ordinary screws, and the height is 11 cm. The screw of the hand screw is fixed in the plastic head by glue. After a period of use, the aging of the glue leads to the loosening of the screw and the plastic head. When the plastic head is stressed, the screw rod comes out of the plastic head, which affects the normal use of the hand screw.
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