What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The research on rivet nuts started in the 1970s in my country and is still in the design and development stage. In the mid-1980s, equipment for the production of blind rivets was introduced from abroad, but no rivet nut has been produced so far. After the inventor's search, no low-carbon steel rivet nut was found to be publicly used.
The pretreatment process is a key process that determines the quality of nickel-phosphorus plating on high-strength bolts. The purpose of this process is to remove the passivation layer on the surface of the bolt and prevent the regeneration of the passivation film. The execution of this process directly determines the degree of bonding between the substrate and the coating. Most of the quality accidents in production are caused by poor pretreatment of bolts. Before plating, the oil, rust and oxide scale attached to the surface of the bolt must be carefully removed; the difference with electroplating is that it should be inspected more carefully, and plating is absolutely not allowed on unclean bolts. ① Inspection of bolts: Visual inspection of the surface quality of bolts requires that any burrs left by processing must be removed, and sharp edges and corners must be rounded. ② Manual degreasing; ensure that the surface of the substrate is free of oil stains. ③ Soak and remove oil; boil the bolts in alkaline water to remove the surface oil. ④ Pickling: In order to prevent the alkaline degreasing solution from contaminating the flash nickel plating tank, electro-activation treatment is carried out with pickling solution before flash nickel plating. ⑤ Electro-activation; electro-activation treatment with acid solution. ⑥ Flash nickel plating; flash nickel plating should be used for low alloy steel to increase the bonding strength between the coating and the substrate.
Rivets are nail-shaped objects with a cap on one end: in riveting, the riveted parts are connected by their own deformation or interference. There are many types of rivets, and they are not restricted in form. Commonly used are R-type rivets, fan rivets, blind rivets, tree-shaped rivets Rivets, semi-circular head, flat head, semi-hollow rivets, solid rivets, countersunk head rivets, blind rivets, hollow rivets, these usually use their own deformation to connect the riveted parts, generally less than 8 mm with cold rivets, larger than this size with Hot riveting, but there are exceptions. For example, the nameplate on some locks is riveted by the interference between the rivet and the lock body hole. The rivet pliers are used to cut rivets. The existing rivet pliers have a simple structure and cannot be riveted according to the The user needs to cut a certain length of rivets, and cutting the rivets is time-consuming and labor-intensive, and it is not convenient for people to use.
Most of the blind hole installation rivets have the characteristics of light weight, reliable connection, high strength, and convenient and quick installation. For example, blind rivets have been widely used in various aerospace vehicles.
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