Bolts: Machine parts, cylindrical screw fasteners with nuts. Two-part fasteners, heads and screws (cylinders with male threads) must be engaged with nuts to secure the two parts in the through holes. This type of connection is called a bolt connection. The bolt connection is a removable connection, as the nut can be removed from the bolt to separate the two parts.
Depending on the method of connectivity: normal and for hinge holes.
Depending on the shape of the head: hexagonal head, round head, square head, countersunk head, etc. Hex heads are the most commonly used. Common sink heads are used wherever a connection is needed.
The English name for U-bolt riding bolts is U-bolt. This is a non-standard task. Its shape is U-shaped. This is also known as a U-bolt. It has screws on both ends and can be used in combination with nuts. It is mainly used for fixed pipe products such as water pipes and automobile leaf springs. It is called a vehicle bolt because it has the same fixed object as the person riding the horse. There are two types, full thread and non-full thread, depending on the thread length.
Depending on the type of screw, it can be classified into two types, coarse and fine, and coarse teeth are not displayed on the bolt mark. According to performance levels, bolts are categorized into grades 3.6,4.8,5.6,5.8,8.8,9.8,10.9, and 12.9. Among them, bolts of 8.8 grade or higher (including grade 8.8) are made of low carbon alloy steel or medium carbon steel and undergo heat treatment (quenching and tempering) generally known as high strength bolts. Class 8.8 and below (except Class 8.8) are often referred to as regular bolts.
Normal bolts can be divided into three grades, A, B and C. Grades A and B are precision bolts, and grade C is thick bolts. For steel structural bolts, coarse C-class bolts are commonly used unless otherwise specified. There are differences between methods at different processing levels. This typically corresponds to the following processing methods:
Bolts for Class A and B bolts are machined from lathes with smooth surfaces and precise dimensions. The performance of this material is 8.8, which is complicated to manufacture and install and relatively expensive.
Class C bolts are made of raw round steel and are not exactly the dimensions. Their material performance rating is 4.6 or 4.8.
Shear connections have large deformations, convenient mounting and low manufacturing costs. It is used to temporarily fix it when it is stretched or attached.
Bolt has many names. Each person’s name may be different. Some people call them screws. Some are called studs. Some people call them fasteners. There are too many names, but the meaning is the same. They are all bolts. Bolt is a general term for fasteners. Bolts use physical and mathematical principles that tilt the rotation of a circle and the friction of an object. Step fastener fixing tool.
Bolts are essential for everyday life and industrial manufacturing. Bolts are also called industrial rice. Bolt applications include electronics, mechanical products, digital products, electrical equipment, mechanical and electrical products. Bolts are also used in ships, vehicles, hydraulic engineering, and even chemical experiments. In any case, bolts are used in many places. Special precision bolts used in digital products. For DVDs, camera miniature bolts, eyewear, watches, electronic products, TV use, universal bolt electrical products, musical instruments, furniture, engineering, construction, bridges, large bolts, nuts, transportation equipment, aircraft, trains and cars. Large and small bolts for. Bolt has an important mission in the industry. As long as there is an industry on earth, the function of bolts is always important.
Countersink heads are often used when a smooth surface with no protrusions is required because the counter sink head is screwed into the part.
Round heads can also be screwed into parts.
The tightening force of the square head may be higher, but the size is larger.
In addition, there are holes in the head and holes to meet the need for locking after installation. These holes prevent the bolts from loosening when subjected to vibration.
Some bolts are unscrewed and polished rods are common and are called thin waist bolts. This type of bolt facilitates variable force connections.
There is a special high-strength bolt in the steel structure, the head is big, and the size changes.
There are also special uses. A specially shaped T-slot bolt most commonly used in machinery and equipment, cut on both sides of the head.
The anchors used to connect the machine to the ground come in a variety of shapes.
It can be tightened with U bolts. Please wait a little.
There are also special weld studs. One end is threaded and one end is not screwed. It can be welded to the part and the other sides can be tightened directly.
Bolts are divided into regular bolts and reaming bolts. The axial force of a normal main bearing can also withstand lower lateral forces. The bolts used for reaming should match the size of the holes and should be used when subjected to lateral forces.
Meaning of level
According to relevant standards, bolt performance grades are divided into 10 grades such as 3.6,4.6,4.8,5.6,6.8,8.8,9.8,10.9 and 12.9. Among them, grade 8.8 and higher bolts are low carbon alloy steel or medium carbon steel, heat treated (quenched and tempered) and are usually called high strength bolts. The rest is often referred to as a regular bolt. The bolt performance rating label consists of two parts that represent the nominal tensile strength value and yield ratio of the bolt material.
There are two types of bolt inspection, manual and mechanical. To minimize the outflow of defective products, typical manufacturing personnel will package or deliver to eliminate defective products (including screw damage, composites, rust, etc.). Visually inspect the product to be used. Another method is to automatically detect the machine, which is mainly the detection of magnetic particles. Magnetic particle inspection is the interaction between a leaking magnetic field and a magnetic powder in a bolt defect. Difference between permeability and magnetic permeability of steel (cracks, inclusions, mixing, etc.). After magnetization, the discontinuous magnetic fields of these materials undergo a fatal change that forms part of the magnetic flux leakage and creates a leakage magnetic field on the surface of the workpiece. As a result, the magnetic powder is attracted to form the magnetic powder, and the magnetic mark is formed. Under proper lighting conditions, the location and shape of the defects are displayed, and the observation and interpretation of the accumulation of these magnetic powders has reached the goal of rejecting the defective product.
Market scenario analysis
Advanced bolts are the foundation of high-end machine manufacturing, and their role can be described as a “bifurcated approach.” On the surface, bolt manufacturing accounts for only a few percent of the machine industry. In essence, it adds much greater value to key components and equipment. Over the years, the bolt industry experienced negative growth in 2012 after double-digit growth in bolts in China, but down about 1.5% year-on-year. The main reason was the lack of market demand, especially after Bolt encountered international anti-dumping, export sales showed a declining trend.
The bolt market is highly competitive and is shifting to brand management.
Over the last decade, China’s bolt development speed has received worldwide attention, and developed countries are also surprised. They can find new big markets, multinationals enter China. When domestic bolt companies suddenly found it difficult to survive in the market, strong competitors were born. In China’s current bolt market, some small and medium-sized bolt companies manufacture a large number of common standard parts. They don’t really give companies core competitiveness, but they are affected by changes in raw materials and labor costs.
From low strength bolts from 4.8 to 6.8, or high strength bolts from 8.8 to 12.9, China’s bolt manufacturing technology level is basically close to the world’s most advanced level used for standard parts and low to medium scale specially shaped bolts. Probably. As low-end products are filled in the mainstream market, high-end, high-precision, high-strength bolts still require only a small portion of the import, and the import price and bid ratio of the product is about 6 times.
We can see that China’s bolt industry is still a “not strong” and “strong and strong” development industry that is far from the United States, Japan, South Korea and Taiwan. There is a lack of technical services to solve mechanical fastening programs, product realization, design, manufacturing, product digitization and management of manufacturing processes. It is understood that the development of bolts in China is putting increasing pressure on resources and the environment. An important way to reduce resource constraints is to develop green manufacturing. Bolt development will continue to evolve in the direction of brand management for some time to facilitate the development of bolting projects in all directions.
On the distribution side, we are exploring various value-added service models to bring value and profit to our customers. Providing a set of bolts leads to providing mechanical fastening solutions, custom services, remote monitoring and more. The proportion of sales services of bolt manufacturers will gradually increase.
Corporate restructuring is a trend, and strategic alliances seek development. Currently, the industrial concentration of Chinese bolt companies is relatively low, seriously limiting the improvement of China’s bolt competitiveness. Years of market opening did not bring core technology. From the above, the main trends are reorganization and strategic alliances between companies. China’s bolt industry must adhere to this trend and trend, strengthen strategic cooperation between companies, and improve the overall competitiveness of China’s bolt. China lacks the development of bolt core technology. At the same time, the living space for low-end products is becoming smaller and smaller, and localized foreign companies also offer significant cost benefits. Coupled with the benefits of having a technology brand, we have begun to enter the market space of our own independent brand.