As soon as the news of the first delivery of the domestic large aircraft C919 to the airline came out, the public paid more and more attention to the aircraft.
So, how was such a huge metal creation born? How does it provide us with a safe and comfortable sailing experience? I'm sure everyone will be curious. Today we will talk about how the huge fuselage of the aircraft is spliced together.
How is the huge fuselage spliced together?
Airplane, as the pearl of human industrial civilization, represents the proof of human civilization's conquest of nature, and with more than a hundred years of development, gradually entered our lives.
Rivets, a common object in industrial design and construction, play a key role in the aircraft manufacturing process. Do you know? Millions of rivets were used in the splicing of the fuselage of the aircraft.
During the assembly of the aircraft, these inconspicuous little rivets are used to connect and reinforce the different components and structures of the fuselage to ensure the integrity and reliability of the entire aircraft. They need to be carefully designed, fabricated and installed, and have the very important function to effectively connect and secure various aircraft structural components, including wings, tails, and front, middle and rear sections of the fuselage.
Some applications of rivets in aircraft construction. Source: Author
Because the aircraft needs to withstand very large wind pressure, gravity, inertial force and other forces during flight. Therefore, the connections between the structural components of the aircraft must be very robust and reliable.
Rivets are a very suitable connection method for aircraft manufacturing because they can withstand a lot of tensile and shear forces and remain stable under different temperature and humidity conditions. In addition, rivets also have smaller space requirements and can be joined without compromising the appearance and aerodynamic performance of the aircraft.
While using a large number of rivets may increase manufacturing and maintenance costs, they can improve the reliability and safety of the aircraft and ensure integrity in extreme situations. Therefore, rivets remain an irreplaceable way of connecting in aircraft construction and maintenance.
How do rivets put the fuselage together?
In general, the structural components of aircraft are composed of various metal materials, including aluminum alloys, titanium alloys, stainless steel, etc. Rivets form a strong connection by passing through two or more structural parts and pulling them together on the other side with the impact force between the rivet head and the tail of the nail, the process of joining which requires rivet guns or other specialized tools.
Aircraft structural components are usually made up of prefabricated parts that have been riveted drilled. During assembly, the installer inserts the rivet into the rivet hole and partially supports the rivet head. Then, a rivet gun is applied to the nail tail to bend the nail tail so that it is firmly attached to the structural parts.
Rivets are usually made of the same or similar material as the structural parts to be joined to ensure stability under different temperature and humidity conditions and to provide maximum joint strength.
We can briefly understand the application of rivets made of different materials in the aircraft manufacturing process:
Aluminum rivets: Aluminum alloy rivets are one of the most commonly used rivets because they are similar to many aircraft structural components. They are commonly used to join aluminum structural components because aluminum rivets have similar corrosion properties to aluminum alloys and can provide maximum joint strength in the high humidity environment of the aircraft.
Aluminum alloy body skin and its rivets. Source: Taken by the author
Titanium rivets: Titanium alloy rivets are also one of the commonly used rivets, titanium alloy rivets are tougher, more corrosion-resistant than aluminum alloy rivets, and can be used at higher temperatures. Due to the higher price of titanium alloys, titanium rivets are often used to join titanium alloy structural parts that require higher strength and more corrosion resistance.
How do I install rivets?
After talking about the types of rivets, everyone must be very curious about how to install these rivets.
The most commonly used construction method in the aircraft manufacturing process is mechanical riveting technology. Both hot and cold riveting are a type of mechanical riveting technology, and their main difference is the temperature of the nail when riveting.
Hot riveting means that when riveting is carried out, the nail is in a high temperature state, and its temperature is usually between 200~500 degrees Celsius. In the process of hot riveting, first use a stove or other heating equipment to heat the nail to make it in a high temperature state, and then insert the hot nail between the two materials that need to be connected, and the riveting is completed after the nail cools. Hot riveting is suitable for joining high-strength materials such as titanium alloys.
Cold riveting means that the nails are at room temperature when riveting is performed. In the process of cold riveting, rivets are pressed between two materials to be joined by hammering or mechanical pressure to complete the riveting. Cold riveting is suitable for joining low-strength materials such as aluminum alloys.
In general, hot riveting is suitable for joining high-strength materials, while cold riveting is suitable for joining low-strength materials. The choice of riveting technology needs to be decided according to the specific material, structure and requirements.
Why is welding not used in aircraft manufacturing?
Welding is also very common in the mechanical joining methods we are familiar with, so why not use welding instead of riveting in aircraft manufacturing? This starts with the difference between the two. Riveting and welding are two different methods of joining materials, and their differences are mainly reflected in the following aspects:
The connection is different: riveting is to join materials by rivets, while welding is to join materials together by melting them and letting them solidify again. Riveting simply creates a hole at the joint, while welding is the fusion of two or more materials together.
The degree of material damage varies: riveting can be joined without causing too much damage to the material, because rivets can be pressed into the material without heating. In contrast, welding requires high temperatures to melt the material, which causes some damage to the material.
Different connection strengths: Higher joint strength can usually be obtained by welding because welding can form a uniform connection in the material. But in some cases, riveting can obtain the same connection strength.
Now everyone must have a better understanding of this little rivet, aircraft manufacturing is not a day's work, it is by countless predecessors in the dark and constantly groped to have the current appearance, the small rivet through the needle lead the aircraft fuselage spliced together, the doorway is also unique.
Similarly, technology will not stand still all the time, and we look forward to future technological advances that will bring even greater progress to our country's aircraft manufacturing industry.
Author丨Zheng Yin, ground engineer; Wang Yixi is a science teacher at the Exhibition and Education Center of Shanghai Science and Technology Museum