Sijin fastener bolt nut screw forge machine

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Executive Vice Mayor of Ningbo visited SIJIN Intelligent
On the morning of January 10, 2023, Hua Wei, the executive vice mayor of Ningbo, accompanied by Lin Yiquan, the deputy director of the Administrative Committee of the High-tech Zone, and the leaders of the Municipal Bureau of Science and Technology, the Municipal Bureau of Economic and Information Technology, the Municipal Bureau of Finance and Political Affairs, the Municipal Military-Civil Integration Office, the High-tech Zone Science and Technology Innovation Bureau, and the Bureau of Industry and Information Technology of the High-tech Zone, came to Sijin Intelligent to carry out the "big visit, big research, big service, big problem solving" activity. Li Zhongming, chairman and general manager of the company, warmly received and accompanied him.
Vice Mayor Hua and his leaders visited the company's production workshop and exhibition hall, and discussed in the conference room. The chairman of the company introduced the development and products of the company, focusing on the research and development progress of the key technology of "multi-station intelligent warm/hot upsetting forming equipment" independently innovated and developed by the company. At present, the warm upsetting forming equipment is completely dependent on import in China, which is a national major short plate equipment. Relying on long-term technical accumulation, Sijin Intelligent has made major technical breakthroughs through several years of technical research, and will conduct trial production of prototype in the near future. Vice Mayor Hua gave full affirmation and support to the innovative spirit of the enterprise. The leaders of Vice Mayor Hua and his party also listened to some of the needs and opinions of SJIN in innovation policy support. As the leader in the field of cold forming equipment segmentation in China, Sijin Intelligent will work hard to create a new level of development in the new year.

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Talking about the Prevention of Looseness in the Connection of Threaded Fasteners---
Analysis on the causes of loose connection of threaded fasteners
The threaded connection is subject to a tightening force in advance before bearing the working load, which is called pre tightening force. Looseness of threaded fasteners refers to the complete or partial loss of pre tightening force of threaded connections. The reasons for looseness of threaded fastener connections mainly include the following aspects.
(l) Initial loosening. After the threaded fastener is tightened, in the working process, such as under the vibration environment, the roughness of its various contact surfaces, including the thread profile, the bearing surface and the contact surface with the connected parts will be reduced due to continuous running in, which will lead to changes in the fastening state, loss of preload, and then loosening. In this case, it is necessary to check the fastening state of threaded fasteners after a period of work, and tighten them again to make them have pre tightening force again.
(2) The bearing surface is compressed and loosened. When the bearing surface of the bolt or nut is subjected to too much pressure, the contact surface between the bearing surface of the bolt or nut and the connected parts will be subject to indentation deformation, which is a plastic deformation. Even if the pressure is removed, it can no longer be restored to the original state, resulting in reduced or even lost pre tightening force of threaded fasteners and loose connection.
(3) Self loosening of threaded connections. Self loosening of threaded connections is the most common cause of failure. We know that when an object is placed on an inclined plane, it is subjected to downward gravity, the support force perpendicular to the inclined plane and the friction force parallel to the inclined plane. When the lateral component is greater than the friction force, the object will slide along the inclined plane. The same is true for bolts. The thread is an equidistant helix, and any section of thread is a diagonal line. The pressure on the bolt is decomposed into axial force and transverse component. When the bolt is subject to vibration, the instantaneous transverse component is greater than the friction force, and the bolt will rotate along the slope. If this happens for a long time, it will become loose.
Common locking measures for threaded fastener connection
(1) Increase friction between threaded fasteners. The looseness of threaded fasteners can be prevented by increasing the friction between threaded fasteners or nut contact. It is not limited by space and can be disassembled and used circularly. It is the most widely used measure so far.
(2) Use welding, gluing or punching riveting and other means to destroy the relationship between the thread movement pairs of threaded fasteners. This method will destroy the original structure of threaded fasteners, making threaded fasteners can not be reused. This method is mainly used for one-time threaded connections.
(3) Add mechanical fasteners. The locking washer, cotter pin and other mechanical fasteners can be used to fix and lock the threaded fasteners. This locking method is widely used in important connection parts, which can effectively prevent the loosening of threaded fasteners. However, the production and installation process of this method is complicated, and the weight of threaded fasteners will also increase.
(4) Double nuts are used for locking. Replace the original single nut with two nuts of the same specification. This double nut assembly can first use 80% of the assembly torque to tighten the inner nut of the double nut, and then use 100% of the torque to lock the outer nut, which can effectively increase the fit of the threads on the two nuts and bolts, and can significantly improve the friction resistance of thread fasteners against loosening. However, this method has the same disadvantage as the third method, that is, it will increase the weight of threaded fasteners. In addition, this method also has certain requirements on the installation space of nuts.
(5) Use elastic washers. Elastic washers mainly include spring elastic washers, wave shaped elastic washers, saddle shaped elastic washers and tooth shaped elastic washers. The principle of using elastic washers is to use the external elastic force of the spring or the friction force of the tooth warping carried by the washers to prevent the connection of threaded fasteners from loosening and provide a certain locking effect for threaded connections. The elastic washer is widely used as one of the anti loose methods because of its simple connection, low cost, convenient installation and use. However, it is worth noting that the elastic gasket material is easy to hydrogen embrittlement, and the anti loosening effect is general. It is not suitable to use elastic gaskets for anti loosening in the parts with severe impact or vibration, and it is not allowed to use elastic gaskets alone for anti loosening in important threaded connections.
(6) Use self-locking nuts. The self-locking nuts are classified according to their functions, including nylon ring embedded nuts, necked nuts and metal locking devices. They are all effective torque type locknuts and are widely used in various important connection parts.
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What does fastener bolt 8.8 mean? How much do you know
The performance grades of bolts for steel structure connection can be divided into more than 10 grades, such as 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9. Among them, bolts of grade 8.8 and above are made of low-carbon alloy steel or medium carbon steel and are generally referred to as high-strength bolts after heat treatment (quenching and tempering), and the rest are generally referred to as ordinary bolts. The bolt property grade designation consists of two parts of figures, representing the nominal tensile strength value and yield strength ratio of the bolt material.
For example, bolts with performance level of 4.6 mean:
The nominal tensile strength of bolt material reaches 400 MPa; The yield ratio of bolt material is 0.6; The nominal yield strength of bolt material reaches 400 × 0.6=240MPa. The material of high-strength bolt with performance grade of 10.9 can reach: the nominal tensile strength of bolt material reaches 1000MPa after heat treatment; The yield ratio of bolt material is 0.9; The nominal yield strength of bolt material reaches 1000 × 0.9=900MPa. The meaning of bolt performance grade is an international standard. Bolts with the same performance grade have the same performance regardless of their material and origin. Only the performance grade can be used in design.
The strength grades 8.8 and 10.9 refer to the shear stress grades 8.8 GPa and 10.9 GPa of the bolt.
8.8 Nominal tensile strength 800N/MM2; Nominal yield strength 640N/MM2.
Generally, the strength of bolts is represented by "X. Y". X * 100=the tensile strength of the bolt, X * 100 * (Y/10)=the yield strength of the bolt (because according to the identification regulations: yield strength/tensile strength=Y/10)
For example: Grade 4.8, the tensile strength of the bolt is 400MPa; Yield strength: 400 * 8/10=320MPa.
In addition, stainless steel bolts are usually marked as A4-70 and A2-70. The meaning is explained otherwise.
measure
In the world today, there are two main units of length measurement. One is the metric system, with the measurement units of meters (m), centimeters (cm), millimeters (mm), etc., which are widely used in Europe, China, Japan and other Southeast Asian regions. The other is the British system, with the measurement unit of inch, which is equivalent to the old market size in China, and is widely used in the United States, Britain and other European and American countries.
Metric measurement: (decimal system) 1m=100 cm=1000 mm
English measurement: (8-base) 1 inch=8 inch 1 inch=25.4mm 3/8?? × 25.4 =9.52
Less than 1/4 of the products are called by serial numbers, such as 4 #, 5 #, 6 #, 7 #, 8 #, 10 #, 12 #
thread
Screw thread is a shape with uniform spiral bulge on the cross section of the external or internal surface of a solid. According to its structural characteristics and uses, it can be divided into three categories: ordinary threads: triangular in tooth shape, used for connecting or fastening parts. The common thread is divided into coarse thread and fine thread according to the thread pitch, and the connection strength of fine thread is higher. Transmission thread: tooth shapes include trapezoid, rectangle, saw and triangle. Sealing thread: used for sealing connection, mainly pipe thread, taper thread and taper pipe thread.
Thread fit grade
Thread fit refers to the loose or tight size between screwed threads. The fit grade is the specified combination of deviation and tolerance on internal and external threads.
1. For the unified inch system thread, the external thread has three grades: 1A, 2A and 3A, and the internal thread has three grades: 1B, 2B and 3B, all of which are clearance fit. The higher the grade number, the tighter the fit. In inch screw threads, the deviation only specifies Class 1A and 2A, Class 3A deviation is zero, and Class 1A and 2A deviation are equal. The greater the number of grades, the smaller the tolerance.
L Class 1A and 1B, very loose tolerance class, applicable to tolerance fit of internal and external threads.
L Grade 2A and 2B are the most common thread tolerance grades specified for inch series mechanical fasteners.
L Grade 3A and 3B, the most tight fit is formed by screwing, which is applicable to fasteners with tight tolerance and is used for key design of safety.
For external threads, Class 1A and 2A have a fit tolerance, while Class 3A does not. Class 1A tolerance is 50% greater than Class 2A tolerance and 75% greater than Class 3A tolerance. For internal threads, Class 2B tolerance is 30% greater than Class 2A tolerance. Grade 1B is 50% larger than Grade 2B and 75% larger than Grade 3B.
2. Metric thread, external thread has three thread grades: 4h, 6h and 6g, and internal thread has three thread grades: 5H, 6H and 7H. (The Japanese standard thread accuracy grade is divided into three grades: I, II and III, and generally II) In metric threads, the basic deviation between H and h is zero. The fundamental deviation of G is positive, and the fundamental deviation of e, f and g is negative.
H is the common tolerance zone position of internal thread, which is generally not used as surface coating or extremely thin phosphating layer. The basic deviation of G position is used for special occasions, such as thicker coating, which is rarely used.
G is usually used for plating 6-9um thin coating. For example, if the product drawing requires 6h bolts, the 6g tolerance zone shall be used for the threads before plating.
It is better to combine the threads into H/g, H/h or G/h. For refined fastener threads such as bolts and nuts, 6H/6g is recommended in the standard.
3. Thread mark
Main geometric parameters of self tapping and self drilling threads
1. Major diameter/tooth outer diameter (d1): it refers to the imaginary cylinder diameter with overlapping thread crown. The major diameter of the thread basically represents the nominal diameter of the thread size.
2. Minor diameter/tooth base diameter (d2): it refers to the imaginary cylinder diameter with the thread base overlapping.
3. Tooth pitch (p): refers to the axial distance of the corresponding two points of adjacent teeth on the meridian. In the English system, the number of teeth per inch (25.4mm) is used to indicate the tooth pitch.
The following lists the tooth pitch (metric system) and tooth number (British system) of common specifications
(1) Metric self tapping tooth:
Specifications: S T 1.5, S T1.9, S T2.2, S T2.6, S T2.9, S T3.3, S T3.5, S T3.9, S T4.2, S T4.8, S T5.5, S T6.3, S T8.0, S T9.5
Pitch: 0.5, 0.6, 0.8, 0.9, 1.1, 1.3, 1.3, 1.3, 1.4, 1.6, 1.8, 2.1, 2.1
(2) English self tapping teeth:
Specifications: 4 #, 5 #, 6 #, 7 #, 8 #, 10 #, 12 #, 14 #
Number of teeth: AB teeth 24, 20, 20, 19, 18, 16, 14, 14
A teeth 24, 20, 18, 16, 15, 12, 11, 10

Called Thread Alias from the Snail to IT Revolution
tượng gọi là Thredson Alias từ ốc cho tới Cách mạng IT
#псевдонимы потоков от улиток к революции ит