What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
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.
Screw name broadcast 1. Machine screw 2. Self-tapping screw 3. Drilling screw 4. Wallboard screw 5. Fiberboard screw 6. Wood screw 7. Hexagonal wood screw 8. Non-prolapse screw 9. Combination screw 10. Micro screw 11. Furniture screws 12. Electronic screws
At present, during assembly of many pin installation mechanisms, the pins need to be installed into the holes or arranged in an orderly manner, and there are many problems in this assembly method. First of all, during assembly, if the hole diameter of the hole product is large, when the pin enters the hole of the hole product, part of the pin entering the hole of the hole product is not fixed, which often leads to slight deviation. In addition, this assembly method is usually only suitable for parts with large apertures and small depths, and when installing multiple pins, it is impossible to automatically install all pins in place due to space constraints. Special tools need to be made for installation operations, and it is easy to cause pins. damage.
An anti-loosening nut structure includes a flat nut and an oblique nut. One end surface of the oblique nut is an oblique surface, and an angle is formed between the oblique surface and the vertical line of the screw hole axis of the oblique nut. Nuts are installed on the bolts one after another, and the mating contact surfaces of the two nuts include the inclined surface, which are tightened in sequence.
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