Service HotlineIn 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.
When processing some disc parts, the mandrel is often used for positioning, and the nut is pressed on it. However, the ordinary nut cannot meet the requirements due to its small end face and poor flatness. The user needs to make the nut, and the cost is high due to single-piece production.
Guangdong Yueluo Hardware Industry Co., Ltd. discloses a rivetless rivet, which includes a nail body and a mandrel, wherein one end of the nail body is provided with a nail body brim, and the nail body brim is provided with a nail body. A coaxial counterbore, the nail body is provided with a through hole coaxial with the nail body, the counterbore is communicated with the through hole and its diameter is larger than the diameter of the through hole, and one end of the mandrel is provided with a mandrel cap The other end is provided with a clamp head, and the end is provided with an elastic groove for retracting the clamp head inward or opening it outward. The clamping head on the core is clamped on the boss formed by the countersunk hole and the through hole. The above-mentioned rivet-free rivet is not only simple, compact and reasonable in structure; riveting is simple and does not require professional tools and equipment; and it is easy to disassemble after riveting, can be reused, has a wide range of applications, and is reliable and stable in connection.
The traditional dismantling of automobile girder rivets is mostly carried out manually, which has many defects such as long disassembly time, low disassembly efficiency, labor-intensive, time-consuming, labor-intensive, low operation safety, difficult protection, and easy injury.
In the manufacture of fasteners, the correct selection of fastener materials is an important part, because the performance of fasteners is closely related to its materials. If the material is improperly or incorrectly selected, the performance may not meet the requirements, the service life may be shortened, or even accidents or processing difficulties may occur, and the manufacturing cost will be high. Therefore, the selection of fastener materials is a very important link. Cold heading steel is a steel for fasteners with high interchangeability produced by cold heading forming process. Because it is formed by metal plastic processing at room temperature, each part has a large amount of deformation and a high deformation speed. Therefore, the performance requirements of cold heading steel raw materials are very strict. On the basis of long-term production practice and user research, combined with GB/T6478-2001 Technical Conditions for Cold Heading and Cold Extrusion Steel GB/T699-1999 High-Quality Carbon Structural Steel and target JISG3507-1991 Cold Heading Characteristics of Carbon Steel Wire Rod for Steel, taking the material requirements of grade 8.8 and grade 9.8 bolts and screws as an example, the determination of various chemical elements. If the C content is too high, the cold formability will be reduced; if it is too low, the mechanical properties of the parts cannot be met, so it is set at 0.25% - 0.55%. Mn can improve the permeability of steel, but adding too much will strengthen the matrix structure and affect the cold forming performance; when the part is quenched and tempered, it has the tendency to promote the growth of austenite grains, so it should be appropriately improved on the basis of international standards. 0.45 % - 0.80 %. Si can strengthen the ferrite and reduce the cold formability. SP is an impurity element, and their existence will cause segregation along the grain boundary, resulting in the embrittlement of the grain boundary and damage to the mechanical properties of the steel. It should be reduced as much as possible. B. The maximum value of boron content is 0.005%, because although boron element can significantly improve the permeability of steel, it will also increase the brittleness of steel. Excessive boron content is very unfavorable for workpieces such as bolts, screws and studs that require good comprehensive mechanical properties.
We have many years of experience in the production and sales of screws, nuts, flat washers, etc. The main products are: rivets, large screws, thin flat head small screws, national standard lifting ring nuts and other products, we can provide you with suitable fastener solutions for you.
