Thread Content
Stud, also known as a double-headed screw or double-headed bolt. It serves as a fixing linkage for connecting machinery; the double-headed bolt has threads on both ends, while the shaft in the middle can be either thick or thin. It is generally used in mining machinery, bridges, automobiles, motorcycles, boiler steel structures, cranes, long-span steel structures, and large buildings, among others. Basic introduction: A bolt refers specifically to a screw with a relatively larger diameter; it can also be without a head, such as a double-headed bolt. Generally, it is not called a \"double-headed bolt\" but rather a \"double-headed stud\". The most common form of a double-ended stud is one with threads at both ends and a smooth shaft in the middle. The most typical applications are: anchor bolts, or similar fixtures in places where thick connections are required and cannot be achieved using ordinary bolts. Specification markings: The thread size is d=M12, the nominal length is L=80 mm, and the performance grade is 4.8. The complete designation for this double-headed bolt is: GB 901 M12×80. Primary uses: 1. It is used in large-scale equipment where accessories such as sight glasses, mechanical seal seats, and reducer frames need to be installed. This is where double-headed bolts come in handy: one end of the bolt is screwed into the main body, and after the accessory is installed, a nut is placed on the other end. Since the accessory is often removed, its threads can wear out or get damaged; using double-headed bolts makes it very convenient to replace them. 2. Double-headed bolts are used when the thickness of the connecting element is very large and the length of the bolts is extremely long. 3. Used for connecting thick plates and in areas where it is not convenient to use hex bolt connections, such as concrete roof trusses, roof beam suspension systems, and single-track beam hangers. Purpose of anti-loosening: In practical applications, external loads such as vibration, changes in load conditions, and high-temperature creep of materials can lead to a reduction in friction. At certain moments, the normal pressure between the threaded parts disappears, resulting in zero friction, which causes the threaded connection to loosen. If this situation repeats itself, the threaded connection will eventually become loose and fail. Therefore, anti-loosening measures must be taken; otherwise, it will affect normal operation and lead to accidents. Basic knowledge: Double-headed bolts are manufactured in accordance with the GB897-GB901 standards. The materials used include Q235, 45#, 40Cr, 35CrMoA, and Q345D. The sizes range from M3mm to M100mm, and the length can be customized to meet customer requirements. High-strength double-headed bolts are available in materials such as 35#, 45#, 35CrMoA, 25Cr2MoV, 304, 316, 304L, 316L, 2H, 2HM, B7, B7M, B16, B8, 8, B8M, and 8M. They are widely used in industries such as power generation, chemicals, oil refining, valves, railways, bridges, steel structures, and automotive and motorcycle parts. The purpose of double-headed bolts is to be used in mining machinery, bridges, cars, motorcycles, boiler steel structures, cranes, large-span steel structures, and large buildings. Notation for double-headed bolts: Generally, a double-headed bolt is denoted as M12×100 GB 901-88 (standard), 35#/35# (material), 8.8 grade/8 grade (tensile strength grade). This means the diameter is 12 mm and the length is 100 mm. GB 901-88 represents the national standard; of course, industry standards can also be used as needed. The standard for double-headed bolts is GB 900-1988. Double-headed bolts help save time and costs, as their structure eliminates the need for tasks such as drilling, punching, threading, riveting, screwing, and finishing. This increases the potential for structural design applications, while also allowing for higher current levels and a smaller depth of penetration. Therefore, it can be welded to very thin sheets. Workpieces welded by stud welding must be welded from one side. It can be welded in all positions, on vertically spaced plates with limitations, with the aid of expanders. Since it is a short-duration welding process with little deformation after welding, no trimming is required. Since the welded structure does not require drilling, there will be no leaks. The joint can achieve very high strength; that is, the strength of the stud weld joint is greater than that of the studs themselves. How to install double-headed bolts: good cost-effectiveness. The advantage of other welding methods lies in their welding power. For mass-produced workpieces, standard studs are low-cost. There are various types of equipment and welding torches, and the cost of purchasing the equipment is relatively low. Depending on the product, it can be made into a multi-station automatic welding machine or a high-precision gantry CNC automatic welding machine. Stud welding offers a high quality repeatability and a low defect rate. However, when using stud welding, it is important to note that, just like other fusion welding methods, there are certain limits on the carbon content in the steel. For structural steel studs, welding should be carried out using the recommended combinations of stud materials and base metal; otherwise, immiscibility may occur between the stud and the base metal. For stud materials and base metal combinations outside the recommended range, it is necessary to determine their weldability through testing, and to assess the possibility of meeting the design requirements for anchor bolts. Surface treatment: Double-headed bolts generally require surface treatment. There are many types of surface treatment for bolts; the most commonly used methods include electroplating, blackening, oxidation, phosphating, and non-electrolytic zinc coating. However, electroplated fasteners account for a large proportion in the actual use of fasteners. It is particularly widely used in industries and fields such as automobiles, tractors, home appliances, instruments, aerospace, and communications. However, for threaded fasteners, it is required not only to have a certain degree of corrosion resistance during use, but also to ensure the interchangeability of the threads, which can also be referred to as mating capability. To simultaneously meet the dual performance requirements of \"corrosion resistance\" and \"interchangeability\" for threaded fasteners in use, it is highly necessary to establish specific standards for electroplated coatings. The GB/T5267.1-2002 standard is one of the standards in the **\"Surface Treatment of Fasteners\" series; this series includes two standards: GB/T5267.1-2002 and GB/T5267.2-2002. This standard is equivalently adopted from the international standard ISO 4042:1999. This standard replaces the GB/T5267-1985 standard. Basic knowledge and maintenance: Producing double-headed bolts requires specialized equipment and machine processing. The actual processing procedure is relatively simple, and it mainly involves the following steps: First, it is necessary to straighten the material using a straightening machine; only after this step can the next one be carried out. The next step is to use a cutting machine to cut the straightened, long pieces into the lengths required by the customer, thus completing the second step. The third step involves using a thread rolling machine to create threads on the cut pieces. At this point, a standard double-headed bolt has been manufactured. Of course, if other requirements are needed, additional processing steps will be required. Generally, a bolt refers to a screw with a relatively larger diameter; according to this definition, a screw has a much smaller diameter compared to a bolt. Double-headed bolts lack heads; they are also sometimes referred to as double-headed studs. A double-headed bolt has threads on both ends, with no threads in the middle; the middle part is a solid shaft. Double-headed bolts are used in large equipment such as reducer frames. In practical use, external loads combined with temperature effects can cause the friction force to decrease; over time, this leads to the loosening and failure of the threaded connection. Therefore, it is necessary to carry out proper maintenance of the double-headed bolts on a regular basis. Double-headed bolts or foot bolts can develop problems due to prolonged mechanical friction. When such problems occur, it is necessary to remove the engine oil pan and carefully inspect the condition of the engine bearing shells, as well as check whether the gap between them is too large; if it is, they should be replaced promptly. When replacing the double-headed bolts, the rod bolts also need to be replaced. For some large equipment such as nail-making machines, if it is noticed during normal operation that the engine is not running stably or if unusual noises are heard, it is necessary to stop the machine immediately for inspection, in order to avoid more serious problems. During each maintenance session, the newly replaced double-headed bolts and other components that have been replaced must be inspected. The inspection should focus on the heads and guiding parts of the double-headed bolts; it is also necessary to carefully check every part of the threads for any cracks or dents. Additionally, the shape of the threads on the double-headed bolts should be checked to ensure that there have been no changes in it. Check whether there are any abnormalities in the pitch; if such abnormalities exist, it must not be used anymore. A torque wrench should be used when installing the rod cover. It must be tightened in accordance with the specified standards; the torque should neither be too high nor too low. Additionally, care should be taken to choose double-headed bolts and studs from a manufacturer that provides compatible products.