Application of Crimping Machines in Aircraft Auxiliary Fuel Tanks

  An aircraft auxiliary fuel tank refers to the space located outside the aircraft fuselage that is used to carry fuel. It is also commonly known as an auxiliary fuel tank. Aircraft auxiliary fuel tanks were the only way to extend an aircraft’s range or loiter time before aerial refueling technology became widespread. The manufacturing process for aircraft auxiliary fuel tanks typically employs crimping and forming—using high-pressure gas or liquid to induce plastic deformation in metal materials, causing them to conform closely to a mold and take on the desired shape.

The main types of crimping machines are:

• Pneumatic press: This machine uses compressed air to apply pressure to metal materials, causing them to conform to a mold and take on the desired shape. Pneumatic presses are particularly suitable for processing lightweight metal materials such as aluminum alloys and titanium alloys with thin walls and large surface areas—such as aircraft fuselages and wings.
• Hydraulic crimping machine: This machine uses hydraulic oil to apply pressure to metal materials, causing them to conform to a mold and take on the desired shape. Hydraulic crimping machines are suitable for processing heavy metal materials—such as steel and copper—with thick walls and small surface areas, including components like aircraft engines and landing gear.
• Hot forging press: This machine uses heated gas or liquid to apply pressure to metal materials, causing them to conform to a mold at high temperatures and take on the desired shape. The hot forging press is particularly suitable for processing metals that are difficult to deform and have high strength, such as firewalls and exhaust hoods for aircraft.

The advantages of compression molding include improved material utilization, reduced production costs, shortened production cycles, and enhanced strength and quality of the finished products. The main types of compression molding are: —Pneumatic crimping, hydraulic crimping, and thermal crimping are respectively suitable for aircraft auxiliary fuel tanks made of different materials and in various shapes. In the manufacturing process of the auxiliary fuel tank body, aluminum alloy sheets are first cut into circular blanks (referred to as “blanking”) using methods such as high-pressure water cutting. Next, the mold used for manufacturing the auxiliary fuel tank is installed onto the crimping machine, and the motion trajectory of the crimping wheel is precisely adjusted. Finally, once the circular blanks are placed onto the mold, the crimping and forming process can begin.

The installation location and shape of aircraft auxiliary fuel tanks can also affect the difficulty and quality of the crimp-forming process. Generally, common installation locations for aircraft auxiliary fuel tanks include the wingtips, beneath the wings, and beneath the fuselage. Auxiliary fuel tanks installed at the wingtips are typically non-discardable and feature a streamlined shape, which helps to suppress vibrations or distortions in the wing structure, such as... The auxiliary fuel tanks of the F-104 fighter jet. Auxiliary fuel tanks mounted under the wings and fuselage are generally detachable. The discarded, flat and streamlined shape can reduce the safe clearance from the ground, such as... The auxiliary fuel tank for the F-16 fighter jet. Different shapes of auxiliary fuel tanks require different crimping molds and parameters, and the design and control of the crimping machine must also take into account factors such as the tank’s dimensions and weight.

                                            As shown in the figure. The auxiliary fuel tank of the F-104 fighter jet As shown in the figure. Auxiliary fuel tank for the F-16 fighter jet

The application of crimping machines in aircraft auxiliary fuel tanks has a history spanning several decades. As aircraft technology continues to evolve, crimping machines have also undergone continuous improvements and innovations to meet the diverse performance requirements of aircraft. Currently, the development trend of crimping machines is moving toward digitalization,智能化 (smartification), flexibility, and integration, aiming to achieve efficient, high-quality, high-precision, and low-consumption manufacturing of aircraft auxiliary fuel tanks.