In the 19th and 20th centuries, many important steel structures were riveted, such as the Eiffel Tower, and the car skeleton. At the end of the 20th century, a large number of structures began to be welded, such as the car skeleton, but some structures that require weight reduction and strength requirements, such as aircraft fuselage, steel bridges, etc., use screw connection technology. What is the specific difference between riveting and screwing, and why is the bridge screwed instead of welded? Answer From the perspective of bearing force, the riveting is better for the bearing capacity and the bearing capacity is poor. The splicing is acceptable for both being pulled and sheared. Welding is also possible by being pulled and sheared, but it is afraid of tearing. From a detachable angle, the splicing is a detachable link, and riveting and welding are not. From the perspective of quality assurance, splicing > riveting > welding, welding is the least easy to check the quality, so civil aviation aircraft use less welding. In terms of changing the material properties of parts, the welding has the greatest influence, the problem of residual stress and deformation is serious, and it can withstand bridges and cars. It is not ideal for the aerodynamic shape of the aircraft surface. At the cost angle, the threaded connection is higher than the riveting than the weld. From the point of adding extra weight, the threaded link is higher than the riveting than the weld. For dissimilar material connections (such as aluminum and titanium, composites and titanium, different series of aluminum alloys), welding is not very good (the different materials are often connected on the aircraft, so it seriously affects the application range of welding). From the above comparison, you can know why cars and bridges are more welded and threaded, and passenger planes are more riveted and threaded. PS1: Thank you for agreeing that, as far as I know, the defects of welding are relatively difficult to control, so the fatigue performance is not stable. PS2: Hot riveting is also common in aviation, especially for larger titanium alloy rivets. To add to this, each connection technology is progressing and different types are derived. For example, riveting, single-sided riveting, self-piercing riveting, etc. Self-piercing riveting seems to be applied more in the automotive industry now, and one piece of equipment is expensive. Single-sided riveting is mainly used for the case where the structure is not open. The packaging industry uses a lot of them, only the low end. There are many more advanced riveting on the aircraft, and it is difficult to localize. For example, welding, laser welding and agitating friction welding are relatively new technologies. Laser welding is mainly characterized by small heat affected zone and small deformation. The mechanism of the friction stir welding is not well studied. The semi-melted state is not the same as other welds. These new technologies are also starting to be used on the plane. Therefore, the view that the welding of automobiles and the riveting of airplanes have been used in the past is actually not clear. As far as bridges are concerned, I don't know much about them, but intuitively think that such large-scale buildings are mostly cost-conscious and insensitive to weight, and often do not use the latest technology. Nonsense two personal views on the connection under the construction situation, if you have a bad week, please forgive me, if there is an error, please axe. If we do not consider the complexity of manufacturing assembly, the mechanical properties of the connection method alone, for the field construction in the civil engineering field, are generally more inclined to use bolting and welding, the main reason is reliability and cost. The reliability of the bolt is the best, especially the high-strength bolt friction type connection. For engineering, it is always better to control the technology, and the smaller the dispersion, the better, so that it is beneficial to achieve lower The higher cost reliability], in the face of such engineering requirements, high-strength bolt friction type connection is currently an ideal way. rivet The steel structure in the field of civil engineering is generally relatively large. The rivets used are not the same as the cold rivets we usually can use to form air guns. It is heated first and then the straight ends are rivet heads with rivet guns. Two more, this should understand how the rivets of the Waibaidu Bridge and the Eiffel Tower are hit! Heating->Installation->Forging In this process, the rivet is actually subjected to two processes of "heat treatment" and "forging". Under today's modern industrial conditions, most of the heat treatment and forging are done in metallurgical and mechanical processing plants, the initial temperature of the heat treatment, and the temperature rise. The cooling rate needs to be controlled, and the forging is also done with high-precision molds. Under the on-site processing environment, it is obvious that both can't be very good [low cost] control. For the field installation of most civil engineering, after the rivet is formed, the temperature is lowered in the outdoor natural environment. This process is actually “annealingâ€. The annealing makes the strength of the steel decrease and the ductility rises. However, unlike the heating in the electric furnace, the thermometer is held. To reduce the amount of factory-controlled heat treatment controlled by the automatic control device. Engineers don't like the uncontrolled annealing that naturally occurs in the field. The rivets are naturally annealed in the components. It is impossible to know exactly how much the strength will be reduced, how much residual stress will be there, and even if there are some accidents such as rain, strong winds or even Brings the "quenching" opposite to "annealing". The final performance of this hot riveted rivet is highly discrete. In order to ensure the overall reliability of the project, the strength of the rivet is not fully utilized, which increases the number of rivets required, resulting in waste and complicated design. In addition to the construction is more annoying, each rivet has to be heated before use, and now the hot riveting rivets in the civil field are not much used. welding Welding is a versatile way. I used to think that welding is a very simple matter. However, after attending the course of steel structure and reading a little information, I found out that the fact is not. The process of welding involves too many things. It is a very large and complicated thing. The whole process is a large collection of various physical and chemical reactions. Welding can be a specialized profession, and it is not a welding of high-level, specialist technical schools. It is a professional of the study-oriented university. The famous domestic welding technology is Harbin Institute of Technology. Many softwares such as MARC and NASTRAN have developed modules for welding to simulate the welding process. Even within the civil engineering field, there are still a large number of scholars studying the influence of welding on the structure, which shows the complexity of welding. Welding will melt the material in the joint area, and the material near the joint area will also be subjected to high temperature. Therefore, under the construction conditions of civil engineering, the residual stress caused by cooling and recrystallization can reach the yield strength of the material because the temperature is higher than the rivet. . The heat treatment effect on the surrounding area is uncontrollable, and the strength and toughness of the surrounding materials change. At the same time, the welding process is not only a physical change, but also reacts with the surrounding gas and flux to produce some residue. On-site welding is generally manual welding. It is always inevitable that people will be hand-wrapped. If they are hand-wrapped, they will leave a bunch of defects such as undercut, cold welding and welding. There are various problems in the total and zero, which have an impact on the structural stiffness and fatigue performance. At the same time, not all materials can be easily welded, that is, weldability, especially in the field construction environment. Metals such as aluminum are not mentioned, the requirements in the factory are very high, and the site is more difficult. The most used of civil engineering is steel, and the weldability of steel is also very different. The high weldability of high-strength steel and alloy steel is not very good. There are many reasons for poor solderability, different materials, aluminum because the melting point of the oxide is too high, the cooling is too fast and the reaction in the welding, the steel is generally caused by the reaction of various alloy components (carbon, other metals, etc.) in the welding. , don't expand too much. In the factory environment, these materials can be welded by welding techniques such as argon arc welding, which require more equipment. However, the site is limited by the simple construction environment, and arc welding is generally used. It is not realistic to weld such materials. There are some high-strength steels that are made of ordinary steel, but they are obtained by various cold and hot processing in the factory environment. It is almost impossible to weld the same performance on the spot. bolt Compared to rivets and welding, bolted joints are much more controlled in the field construction environment, there is no heating process, and there is no problem of uncontrolled heat treatment. The components and bolts are produced in the factory environment, and the product consistency is quite good. Pressure-bearing connections are similar to rivets but bolt strength and quality stability are better than rivets. The friction type connection is not the same, and there is a bit of a tough problem in the field construction - friction control. Friction is affected by contact surface pressure and surface roughness, but now shear bolts, torque wrenches and surface treatments have solved this problem. One end of the torsion bolt is a round head similar to a rivet. There is no corner. The bolt is passed through the spline at the other end (or the plum head). There is a shrinking neck between the spline and the bolt. When the member and the bolt are rubbed. The torque generated by the force reaches the torsion limit of the neck and the spline is twisted off. The torque wrench can adjust the maximum output torque, and then it will slip after it is used. It can be used to tighten the hexagon bolt to achieve the same effect as the shear bolt. It won't be because the old king has a cold and can't screw up, and it won't be too excited because the pharaoh is going to go next door tonight (the bolts are too tight and will be bad). The surface treatment can be carried out in the factory. After sandblasting, sanding or sandblasting can be applied to the anti-rust paint, so the friction coefficient is quite stable after the treatment. Using the friction type connection, the force transmission between the members is through the friction force, so the connection performance is basically equivalent to the component itself, which is the most consistent with the design concept, and the strength stiffness and fatigue performance are guaranteed. Do you think I have to say that the bolt connection is long live, NO! Anyone who has installed a steel structure on site knows how painful the bolted connection is. It is not uncommon for the bolt hole to be inactive due to various reasons (manufacturing error, welding deformation, stress deformation, etc.). Using Reinhardt's sledgehammer, the shear pin was punched into the hole, and the hole was hardened. As a result, the two members did not fit together, and the bolt was not tightened. On-site punching correction may weaken the component too much, sometimes it is necessary to repair the weld or make a steel sleeve to fill the hole, which is very troublesome. In many cases, it is not necessary to connect the plates directly between the components. Also, don't forget the splined bolts that are screwed off. These calculations will greatly increase the amount of material. The bolts are more expensive than the ordinary Q345Q235, so they are bolted. The price is moving. There is no such trouble in welding, and the position difference can be directly welded without too much difference. Another point of welding is that the speed is fast, and the welding torch can not only be connected but also cut, and the construction error can be quickly corrected. Most of the welding can be carried out directly between the components without the need for additional connecting plates, and the material is also relatively economical. At the same time, the weldable steel for arc welding is generally not very strong, the weld strength can be higher than the base metal, and the welding area is full of the entire structure, leaving enough safety margin and reliability to ensure sufficient. Therefore, welding is very common when installing on site because it is really convenient. In fact, when various methods are not applicable, it is impossible to obtain the required stable quality at a sufficiently low cost in a specific environment. The reason for the unstable welding quality on the site is that the external environment is uncontrollable and human operation is not reliable. Therefore, if the welding is moved to the factory environment, it is very different. The automatic welding machine, the closed workshop, after the welding, there are straightening, grinding, heat treatment and other processes to help adjust the welding deformation, reduce the residual stress, and have large flaw detection equipment. Helps detect weld quality and can be repaired. Therefore, the best way to produce some non-standard components in a factory environment is still welding. The same rivet can be improved by some better techniques, such as the heating process, which was earlier in the charcoal furnace. Now there is an electric furnace, which uses the principle of eddy current heating to quickly heat the rivet. Because the rivet is cooled after heating, it will have considerable pressure on the plate, which can compress the plate. Because the rivet itself has better toughness, it is sometimes used for the structure subjected to dynamic load. It is still necessary to repair some old steel bridges. Continue to use rivets, such as the picture below, selected from the Guangzhou Daily News to repair the Haizhu Bridge news. Because of the large and bulky nature of the civil engineering, this hot rivet is indeed small in the civil engineering field, but when connecting some light skins and thin plates, cold rivets (such as the most common rivets) are lighter than bolts, and the thin plates are not easy to weld. It can also be applied to the connection of different types of materials, and the strength required for the connection is not large, it is quite suitable. The civil engineering field is generally used to connect some thin-walled steel and profiled steel plates, which are very thin components. The most common one is the temporary enclosure of the construction site. So, in what way to connect, consider: 1. Requirements for mechanical properties; 2. Conditions of construction; 3. Allowed money. Each connection has its own range of applications. There are many uses for rivets in the field of aerospace, but that is not my specialty, so many other aerospace friends say more. I summarize it from the perspective of shipbuilding: Riveted has been widely used in ship construction before World War II and is now obsolete. Despite the elimination of the shipbuilding industry, modern aircraft manufacturing still uses riveting, but the riveting of modern aircraft is quite different from the riveting of ships before World War II. Due to the need to reduce the empty weight, most of the aircraft materials are aluminum and composites. Aluminum is not easy to weld, and composite materials cannot be welded. Considering that the aircraft must also be waterproof, riveting is the best choice for aircraft construction. Bolted connections are mostly used only for land buildings (buildings, bridges, cranes, installations on decks of ships/offshore platforms). The bolted structure is easy to remove, but it is not impervious to water, and the bolt itself is prone to rust (water can accumulate in the groove of the bolt). Welded is basically the only component joining method used in the shipbuilding industry today (completely replacing riveted) and also used in land construction. The advantage of welding is that it does not seep water compared to bolted connections. Compared to riveting, the advantages of welding are speed and the quality of contemporary welding technology is more reliable. The disadvantage is that it is not easy to dismantle. It must be blown up or cut off when it is removed, which will damage the reusability of raw materials. Why is riveting eliminated by the shipbuilding industry? In addition to slow construction, the riveted hull structure before World War II can be compared to a soda cracker, and the new Titanic built with modern welded technology can be likened to a plasticine. The key to any large metal structure is actually the connection point of the part! This is true for ships, airplanes, vehicles or rockets. The two connected boards cannot be stronger than a one-time synthetic board. About welding: Conservative, you can't fully believe the welding results in the factory. Even if the welding material is stronger than the parent material, the parent material on the boundary line will still weaken after welding. Remember! The previous ones have already said very well. Let me take the actual project as an example. (I am good at teaching and learning.) Take the steel structure of a portal steel frame as an example. Because riveting is costly and difficult to construct for ordinary steel structures, let's discuss welding and bolting. Our requirements for a factory with a crane are as follows: 1. The plant itself meets the reliability requirements, namely safety, comfort and durability. 2. The crane is a power equipment, so it is necessary to meet the power load requirements of the crane. 3. Whether the factory needs to be dismantled after the factory is removed from the factory, and how much space the material can be reused. First, let's start with the steel column and foundation connection of the door steel. The column legs are just connected and hinged. For power equipment, we tend to make the connection just because the dynamic load of the crane, especially the horizontal brake load, can easily cause the overall instability. We can use welding or bolting at the foot of the column, but the welding is not very operative here. Because the column foot and the base under the column are connected, if it is full welding, it is easy to cause problems such as insufficient weld seam, and it is difficult to ensure the stability of the column during the welding process. You look at the electrode in your hand as you lick your ass, and look at the pillars that are swaying and swaying over you, afraid, no, you say! Secondly, let's talk about the beam-column joints. This doesn't matter. As long as it is made of just joints, bolts and welds can be used, but the welds are prone to rust, and the manufacturers of steel structures are reliable, and the bolt holes are a little biased. Cry you. Once again, the anti-wind column must be hinged, so don't hesitate, hold the bolt and smash it, and screw it up. Finally, the ox leg is so ugly, looking at the headache, how much welding is good, why? Twist you in minutes with bolts. . Look again, knock on the blackboard! There are so many places to screw so many bolts! In the end, if a certain day is really a factory yellow (the boss does not hit me), the bolts are connected so much, the two of them screwed the factory one day, and sold it at night~~ In summary, if the connection needs to be hinged, use bolts. If it is just pick up, look at the situation, see the difficulty, see the welder's brother's mood and level. . Bolting is trouble-free, the technical level is not high, but the requirements are high. The welding connection saves money, the material requirements are high, and the welder has higher requirements. The test unit is required to test, but the manufacturer is very happy, so it will not be a few millimeters to go to the field, so he will be willing to give you discounted. However, if you finally think about the government demolition and requisition the land of your factory, you can use the bolt connection to get the compensation for the factory today, and find the block and build it like a building block tomorrow~ Make money, remember to invite me to dinner! @Summeræ¥ The art is not refined, and the daring throws bricks. If you have limited knowledge, let me talk about the steel bridge field. Riveting is not very useful now, and I know less. Compared with the other two connection methods, the main advantage of the riveting is that the adaptability is good. It is also irrelevant that the holes of the two plates are slightly offset. Anyway, when it is hit, it is still soft, and it can be closely attached by knocking. (To tell the story, the workers who used to rive up were really open. One person used pliers to clip the hot rivets out of the stove, and throw them away. Another person ten meters away [clamped] caught the heat. Go in.) The shortcomings are also obvious. Because of the need to burn soft in the field, the material used for the rivet does not have much strength, and the rigidity is not large. This explains why the rivet gradually withdraws from the field of bridge engineering. In the past, the strength of the steel itself was low, and the rivet was not the weak link of the structure. Now the strength of the steel is improved, but the strength of the rivet is not fast enough, which becomes a weak link of the structure, so it is not suitable. Adopted. The bolts of the bridges are mostly high-strength bolts. The two steel plates are firmly pressed together, and the load is mainly supported by the friction between the steel plates. It is a mature and widely used connection method. When it comes to the advantages of bolted connections, it depends on who: The advantages of bolted connections compared to riveting are: High intensity; High rigidity (cause: friction type high-strength bolts do not allow slippage between the connected plates, so the connection section stiffness is basically the same as the plate itself); The construction quality is easy to guarantee (cause: the construction of high-strength bolts has clear torque requirements for the initial and final tightening, so as long as the construction is strictly in accordance with the regulations, the quality will not change with the quality of the construction personnel). The advantages of bolted connections compared to welding are: Good fatigue resistance (cause: no obvious local defects will occur in the construction, so the stress concentration is relatively small, there is no obvious source of fatigue); Easy to repair and replace; The construction quality is easy to guarantee (the reason has been mentioned before). Disadvantages, å’± also said two points: The disadvantages of bolted connections compared to riveting are: High price; Can't think of it... The disadvantages of bolted connections compared to welding are: There are many processes and complicated processes (cause: first of all, it is very difficult to punch holes, and then you have to punch holes in the field, first screw, and finally screw). But this is not absolute. For example, some workers climbed up with a wrench, but it is difficult to get the welding equipment to the past; The construction accuracy is high (cause: the bolt connection requires the holes to be accurately aligned. If the components are completed in June, the site will be installed in October, and the temperature will be deformed to make the holes far worse), even if It is one of the largest manufacturers in China, and sometimes it needs to be aligned on the spot; Nowadays, the most used in the field of bridges is welding. There is no comparison with the riveting, let alone the pros and cons of the bolting. The advantages of soldering compared to bolted connections are: Better overall; The process is simple, easy to factory, and the quality of the automated welding in the factory is very secure. (Seeing that alumni have said this as "depending on the factory", some people are confused, this is not our pursuit); Adaptability (cause: even if there are some deviations in the production of the components, we can still weld them) The disadvantages of soldering compared to bolted connections are: Residual stress, residual deformation (cause: due to the unevenness and non-synchronization of heating and cooling during welding, a series of self-balancing stress and self-coordinating deformation will occur inside the structure, affecting performance); The quality of on-site welding is highly discrete (cause: the field welding is mostly artificial welding, this quality depends on the craftsmanship. In addition, the posture of the components can not be adjusted during on-site welding, and the welding quality is greatly affected by the welding attitude); Anti-fatigue performance is relatively poor, here is mainly manual welding (cause: manual welding is likely to cause welding tumors, undercuts, slag inclusions, etc., resulting in greater stress concentration, often become the source of fatigue damage) Well, all three connection methods are finished, summed up (still limited to the field of bridges). Riveting: something from the old days, it should be eliminated; Bolting: The top of the mechanical properties is that the structure is complicated, the holes are difficult to match, but the fatigue resistance is good, even if it is broken, it can be changed. Suitable for fatigue control, it is also the most secure connection method for on-site construction; Welding: The structure is simple, the factory automatic welding efficiency is high, and the performance is not said, but the quality of the field welding can only ask the earth to ask the earth, and often become the source of fatigue. It is most suitable for the fabrication of components and units in the factory, as well as for field connections in non-fatigue control positions. I am finished, is there any clarity? @万æ°é¾™ Riveting and bolting are all areas of mechanical connection. Riveting is achieved by extrusion deformation of the rivet. The connection parameters of the riveted joint cannot be completely controlled, and it is deformed during the connection process, and the bearing capacity is poor. The feature is that the connection is convenient, but the quality cannot be guaranteed. And its connection method determines that it can't be done too much. If it is too big, the connection is difficult. Second, the riveted joint is destroyed during the extrusion process. Bolted joints should be the most widely used, and as standard parts, the production technology is mature, the connection is convenient, and the cost is low. Moreover, there are mature anti-loosening and rust-preventing technologies, and the connection is also higher than the riveting in the same size. In short, there are many advantages. The welding is to join the two metal plates by adding materials, which is only suitable for metal and thin-walled parts. In other words, if the thickness is too large, a thin layer of soldering layer close to the surface cannot guarantee the connection strength. Moreover, heat radiation is generated during the welding process, which causes changes in the microstructure of the metal, which tends to cause stress concentration. If there is special demand, heat treatment is needed to improve the mechanical properties. For the problem of the subject, the welding is used in the car. First, the bearing requirements are not high. Secondly, the welding is the most suitable for this size structure. If bolts or rivets are used, the strength will be greatly reduced. As for the aircraft fuselage, it is spliced ​​into a larger component by many components, and then the components are assembled. For such large-sized components, welding is very difficult and needs to be docked during the welding process. No movement occurs. Moreover, due to the trend of lightweight development of aircraft, many parts have been made of non-metallic materials, and welding is not used. As for the bridge, let alone the strength can meet the requirements. If welding is used, it cannot be heat treated after processing in actual production. The impact load during use will cause damage to the stress concentration part, which is the most deadly. . Moreover, it is necessary to maintain the joint of the connecting members during the welding process, and it is not possible to shake a little, which is difficult to achieve in the field. The bolt connection is very easy. Insert the bolt into the connection hole and tighten it. It is simple, convenient and efficient. To sum up, the different connection methods are the simplest and lowest cost optimal solution under the premise of ensuring the connection strength. A shallow opinion of a mechanical student. @舒宇 Just after reviewing the basic research and development of process equipment, talk about the views. The biggest problem with riveting and studs is that they conflict with the big goal of weight loss. There is still a problem with the stud, which is the slippery wire and loose. The advantage of both is that the principle is simple and the technology is mature. There are many kinds of welding, friction welding, stirring welding, laser arc welding. The advantage is that weight loss can be achieved. The disadvantage is that some metal materials have poor weldability, are prone to cracking, deformation, and the like. For the same material, welding of dissimilar materials requires different welding techniques. In addition to the process, automated welding equipment is also difficult to manufacture. @people who use Zhihu welding Advantages: Suitable for all shapes, saving steel and labor, automatic operation, high production efficiency Disadvantages: the quality is greatly affected by the welding consumables and operation Riveting Advantages: The connection force is reliable, the toughness and plasticity are good, the quality is easy to check, and it is often used for structures subjected to dynamic loads. Disadvantages: scrap steel waste Bolts are divided into ordinary bolts and high-strength bolts Ordinary bolts are convenient to load and unload and should not be cut. High-strength bolts contain the advantages of common bolts and riveting and are now available to replace riveting. ================================================ Extracted from the Basic Principles of Steel Structure edited by Academician Shen @idontwan The defects of the riveted parts are easy to observe and can be applied to some fields of aviation, shipbuilding and bridges. High welding efficiency and high strength. Widely used in mechanical equipment, automotive manufacturing. The bolt connection is easy to disassemble and is mainly used in the assembly process. For example, aircraft windows, if welded, open welding is very troublesome to repair. And if you open the weld in flight, there is a risk of crash. Therefore, riveting can make defects found during maintenance and easy to repair. For example, if the metal structural parts on the chassis of the car are riveted, the production efficiency is low and the strength is not guaranteed. For example, in the manufacture of a bird's nest stadium, if all the components are welded, the stress is too concentrated, and the welding amount is too large at some places, which is not convenient for construction. Therefore, it is the safest solution to make a strip of "twigs" in the factory and then assemble them on site. My riveting teacher repaired the riveted bridge built by the Japanese, and the rivet was gas-fired and burned. When the cold was down, the sledgehammer went inside and got it. If the weld is cracked and the weld is inside, how do you repair it? It is impossible to remove the bridge and re-weld it. @æ¨ä¸–é‘« Simply answer two points, the riveting is not clear. The bolting link has good toughness, and the connecting plate and the bolt have good ductility. In the case of large deformation, the bearing capacity will not suddenly decrease, and the seismic resistance is strong. And when the node load is overrun, it can be easily observed. The toughness of the weld is not good, especially at low temperatures. During the construction process, bolting construction is not as convenient as welding, but the construction quality is easy to control. Welding, especially on-site welding, can cause cracks, bubbles, slag inclusions, leakage welds, unmelted, through-welding defects, etc., which are highly demanding for welders and are not easy to observe. The common ultrasonic non-destructive testing technology is higher than the high-strength bolt torque detection, and the equipment and labor costs are higher. @people who use Zhihu Forced according to some of your own intuitive understanding The riveting process is the simplest. In the impression, the rivet itself is a casting, and the riveting only needs to be punched on the object to make a joint. In case of shortcomings, the riveting is done by the deformation of the rivet, in other words: given a large enough longitudinal impact, the rivet may deform again and collapse... (Disney produced a "Asian" in the 1990s Atlantis, the submarine inside was guarded by a beast and hit a rifle in the cabin. The screw process is obviously more complicated, because not all screws are self-working (that is, the female lines are carved in the holes by themselves), so in many cases not only the screws of the screws themselves but also the lathes, the joints The hole also needs a machine tool to engrave the yin (I can't say what the specific process is here). Compared to riveting, the screw is stronger when facing direct impact. However, if the joint receives a long-term reciprocating vibration, especially if the vibration is at a suitable frequency, the screw may spin and slowly become loose. One more point here is that since the threaded surface of the screw is a friction surface, this position is particularly prone to rust and there is basically no way to protect it with plating. The welding process is the most complicated... I don’t know how to say it. In terms of advantages, welding is not just a splicing, but to some extent it is fusion. Therefore, the welding should be better than the first two in terms of strength, watertightness, airtightness, and electrical conductivity. @DoomExp Disadvantages of welding: 1. The deformation is serious, the high temperature of the welding will lead to the stress concentration at the welding place, so many high-precision, high-surface joints with high requirements for the surface connection, glue bonding. 2. It is not easy to check. After welding, special testing equipment should be used to detect whether there is any defect, and the cost will become higher. There are also restrictions on the venue. 3. It is difficult to disassemble. If the welding is wrong, re-cut and re-weld. Advantages of welding: 1. Good connection performance, practical for large-scale equipment welding, good for materials of different shapes and sizes. 2. Good rigidity, good overall performance and good sealing. @王平 Bolts for easy removal. Disadvantages take up space and increase weight. If you do not need to remove the place, use less bolts. Welding, equipment, time required, and not all materials can be welded. Riveting, the use of places is getting less and less. @木易 Static objects, such as bridges, towers, and construction screws; Moving objects or parts are welded or riveted for the simple reason that the movement will loosen the screws. It is not always possible to check each screw before taking off the plane! The welding is optimal because both the riveting and the screwing are connected by friction to the two parts. If there is a translational force between the two parts, it is not suitable for riveting and screwing. Welding is equivalent to turning two parts into one, which is the most stable. In addition, if there is a force in the translation direction between the two parts, if there is a backing to each other, it can be considered to be fixed by screws. The so-called backing is that, for example, one part has a groove and the other part has a convex rail, which is matched with each other, and can be fixed by screws. The principle is to convert the translational friction force into the pressure against the mountain. Sustainability and stability are greatly improved. @åŸæ¢¦ Riveting is a large range, bolts are a type of riveting and are the most common one. Bolted or high-strength riveting is more robust than welding, the only drawback being the high cost. The riveting of the aircraft is stronger than ordinary screw links and is lighter, such as bom nail huck nails. The aircraft has a high safety factor, so it cannot be welded and only riveted. Because the high-speed rail car body is not so high, it can be welded. The car is required to be lower, and the welding can be done. But there are also car manufacturers with fever, such as Land Rover has a car, full body aluminum alloy, and riveted like an airplane, you don't ask for the price, you can't afford it. The bridge is not my professional, it may be for some special requirements, such as the bridge can not be too heavy, using some high-strength steel, generally high-strength steel can not be welded, or poor welding performance. Or the seaside has corrosion resistance requirements, and the corrosion resistant steel is also poorly welded, so it is safe and secure, and it is riveted. Measuring Tape,Small Tape Measure,Custom Tape Measure,Personalized Tape Measure SHANGQIU CHAOYUE MEASURING TOOLS CO., LTD , https://www.calibrateds.com
