Service HotlineLocking of screws belongs to the prior art. Or by means of a visual method (X-ray control) a more or less complex aiming device is inserted into the transverse hole of the screw. In both cases a certain misalignment is unavoidable, ie the screw may not be coaxial with the central axis of the transverse hole and deviate from it by a certain value. In order for the locking screw to pass into and through the transverse hole despite this misalignment, the outer diameter of the screw is determined to be a size smaller than the diameter of the transverse hole. If the aiming is not maintained within this small dimension value, the locking screw can pass through the transverse hole without difficulty despite the aiming error. Now, however, the locking screw has a certain clearance relative to the transverse hole due to the determination of a smaller size value.
Comparing the physical properties of stainless steel and carbon steel, the density of carbon steel is slightly higher than that of ferritic and martensitic stainless steel, but slightly lower than that of austenitic stainless steel; the resistivity is based on carbon steel, ferritic, martensitic and The order of austenitic stainless steel is increasing; the order of linear expansion coefficient is similar, austenitic stainless steel is the highest and carbon steel is the smallest; carbon steel, ferritic and martensitic stainless steel are magnetic, austenitic stainless steel is non-magnetic, But its cold work hardening will generate magnetism when it is transformed into intensite, and heat treatment method can be used to eliminate this martensitic structure and restore its non-magnetic properties. Compared with carbon steel, austenitic stainless steel has the following characteristics: 1) High electronegative rate, which is about 5 times that of carbon steel. 2) The large coefficient of linear expansion is 40% larger than that of carbon steel, and with the increase of temperature, the value of the coefficient of linear expansion of stainless steel screws increases accordingly. 3) Low thermal conductivity, about 1/3 of carbon steel.
In many national standards, there will be a division of intensity levels. Combination screws are no exception. The strength grade of the combined screw is divided according to the material of the screw wire and the hardness index of the screw wire. General combination screw materials are divided into stainless steel and iron, stainless steel is divided into stainless steel 201, stainless steel 304 and stainless steel 316 and so on. Iron is divided into three types: low carbon steel, medium carbon steel, and high carbon steel. Carbon steel combination screws refer to iron combination screws. Generally, iron combination screws are classified into grades 4.8, 8.8, 10.9, and 12.9. However, the combination screws of grade 10.9 and grade 12.9 are rarely used in the market, so we will not talk about them here. And the combination screws on the market are more commonly used combination screws of grade 4.8 and 8.8. 4.8 grade combination screws are generally made of 1010A screw wire rods. After the screw wire rods are beaten into screws, they are combined with spring flat washers. After production, this 4.8 grade combination screw does not need to be hardened. Its hardness can reach 4.8. 8.8 grade combination screws are generally made of screw wire 10B21 piers. After the screw and wire piers are made into screws, they are equipped with spring washers and flat washers. They can pass through the automatic elastic flat washer machine to rub the three pieces together. Fasten the spring-flat washer combination on the screw, and the spring-flat washer will not fall off. After the combination screw is produced, it needs to be hardened to make the hardness reach 8.8. After the hardness reaches 8.8, we need to take it for electroplating. In order to prevent hydrogen embrittlement of the spring washer in the 8.8-level combination screw with added hardness, it is easy to break. In this way, we have to perform hydrogen removal treatment on the hardened combined screws, and only after the hydrogen removal can be plated. In short, there are many kinds of standard grades of combined screw strength, but generally only two types are used in the market, one is the 4.8-level combined screw strength, and the other is the 8.8-level combined screw strength. 4.8-level combination screws are the most used in the market and customer needs, and have a wide range of applications. As for the standard strength of 8.8-level combination screws, we generally refer to 8.8-level hexagon socket head combination screws, 8.8-level pan head combination screws, and 8.8-level external hexagon combination screws. These three are more commonly used.
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.
The circuit board is often the circuit board that plays a major role in electrical equipment, and the main electrical components of the circuit are often integrated on the motherboard. For single-layer circuit motherboards, rivets are used on the circuit motherboard in order to make the components more firmly fixed on the pcb board. In the prior art, the rivets are all set on the circuit board by an automatic riveting machine, which is controlled by an internal program to automatically complete the rivet-setting operation. This internal program is pre-set. If you need to rivet different motherboards, you must change the internal program. If you need to temporarily rivet a circuit board, it will be cumbersome to change the program again. Moreover, this kind of automation equipment is produced on a large scale and is not suitable for temporary operations.
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