What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
As my digital TV technology becomes more and more mature, more and more people with digital-to-analog signal conversion function enter people's lives. Therefore, the number of production and processing is also increasing day by day. There are many requirements for the form, reliability and cost of PCB fixing screws in production. One of the existing fixing methods is to fix by means of bolts and nuts. The operation steps are to place the PCB board on the inner threaded copper column connected to the casing, and pass through the bolts with fine teeth. Screw holes on the PCB board, and then fix them on the copper posts with nuts. The connection method of this solution is reliable, but its manufacturing cost is high, and the copper column and the metal shell need to be screwed together, resulting in low production efficiency and high cost. In addition, there is also a common way that the PCB is supported by a plastic column, and the self-tapping screw is passed through the screw hole on the PCB board, and the PCB board and the metal bottom shell are connected by the self-tapping thread on the screw. The main disadvantage of this solution is that after the screw is fixed on the metal shell, the screw head is exposed at the bottom of the machine. If the user is not careful during use, the hand scratching phenomenon will occur, which will bring changes and harm to the user's use. . And when the machine slides on the desktop, if the screw head is too exposed, it will scratch the desktop. Therefore, how to provide a PCB fixing method with convenient operation, reliable connection and low production cost is a technical problem to be solved urgently in the industry.
Fasteners are a type of mechanical parts that are used for fastening connections and are widely used. All kinds of fasteners can be seen on all kinds of machinery, equipment, vehicles, ships, railways, bridges, buildings, structures, tools, instruments, meters and supplies. It is characterized by a wide variety of specifications, different performance uses, and a very high degree of standardization, serialization and generalization. Therefore, some people also refer to a type of fasteners with existing national standards as standard fasteners, or simply as standard parts. Fasteners are the most widely used mechanical foundations. With my country's entry into the WTO in 2001, it has entered the ranks of major international trade countries. my country's fastener products are exported to many countries in the world, and fastener products from all over the world are also pouring into the Chinese market. Fasteners, as one of the products with the largest import and export volume in my country, are in line with international standards, which have important practical significance and practical significance for promoting Chinese fastener enterprises to go to the world and promoting fastener enterprises to fully participate in international cooperation and competition. strategic significance. Due to the specifications, dimensions, tolerances, weights, properties, surface conditions, marking methods, and specific requirements of items such as acceptance inspection, marking and packaging for each specific fastener product.
Convex washers are mainly punched out of iron plates. The shape is generally a flat washer with a hole in the middle. Flat washers are usually thin pieces of various shapes to reduce friction, prevent leakage, isolate, prevent loosening or Dispersing pressure, the rationality of its design structure and the safety during use are very important.
Traditionally, the pressure rivets on the product are all beaten by hand by workers, resulting in high scrap rate and low efficiency, and this rivet is not a traditional rivet, so it is difficult to locate and requires high pressure. The rivets are thin, and the pressure is too large to cause deformation of the rivets. If the pressure is too small, it cannot be riveted. Without special positioning and tooling, it cannot be riveted on the riveting machine. The quality of the products produced in this way is difficult to guarantee, and the quality levels of the products in the same batch are uneven. Affect delivery time.
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