Power spinning forming and its advantages

As a new technology in modern plastic processing, powerful spinning has obvious advantages in the production of thin-walled high-precision rotating parts:

(1) The strength and hardness of the material after strong spinning are about 35%~45% higher than that of the base material. Therefore, strong spinning can effectively reduce the design wall thickness and weight of the part, and its fatigue performance can also be significantly improved.

(2) Power spinning is an integral forming technology. The formed parts have no busbar welds, so the overall performance of the parts is improved, especially the fatigue life can be significantly improved.

(3) No-cutting processing with powerful spinning, which improves material utilization and reduces production costs.

(4) Due to the high rate of thinning, strong spinning can effectively detect metallurgical defects in the base metal, and the effect of these defects is very insignificant or even impossible when other non-destructive testing methods such as ultrasound are used.

(5) The dimensional tolerance and shape tolerance of the powerful spinning parts are relatively small.

(6) Power spinning belongs to half-mold forming and does not require a complete set of molds, so mold costs and manufacturing cycles are greatly reduced.

(7) Power spinning belongs to partial forming. Although the unit pressure on the contact surface is large, the contact area between the rotary wheel and the workpiece is small, so the total deformation force and the tonnage of the machine tool are very low compared to other pressure processing methods.

(8) Power spinning belongs to axial drawing forming, and the material in the deformation zone is in a two-way or three-way compressive stress state, so a higher degree of deformation can be achieved.

Based on the above advantages, especially the improvement of the strength, hardness and fatigue resistance of parts after powerful spinning, powerful spinning technology has been widely used in the manufacture of parts in the aerospace field.

Application of Power Spinning Technology in Aviation Manufacturing Technology

Spinning technology has been widely used in aerospace manufacturing. On airplanes, various hoods, auxiliary fuel tanks, air intakes, gas cylinders, tie rods, slide rails, and actuators have all been formed by spinning (Figure 1). On the engine, the propeller cap, casing, lip, intake cone, nozzle, nozzle, etc. are also partially formed by spinning. This kind of parts has complex structure, special materials and large size. After the spinning forming process is adopted, the integrity of the structural parts is improved, the welding seam and the deformation of the parts are reduced, and the workload of manual calibration is reduced. More importantly, , As the material strength increases after spinning, the design wall thickness of the parts can be reduced, thereby reducing the weight of the whole machine and improving the reliability of the whole machine.

The powerful spinning forming of the auxiliary fuel tank has the most technical advantages. The auxiliary fuel tank is 2~3m long. The traditional manufacturing process is to split and form and then weld. The number of splits is more than 6 petals. Therefore, the number of welds in the entire auxiliary tank is more than a dozen, and the welding deformation is large, and a lot of calibration procedures are required. Large quantity and long manufacturing cycle. Divide the auxiliary fuel tank into two symmetrical left and right parts from the middle, adopt a powerful spinning process, form a thick plate twice, and then weld in the middle, reducing the original dozen welds into one, greatly improving the accuracy and overall of the auxiliary fuel tank Strength, reduce the manufacturing cycle and tooling manufacturing costs.

There are various gas cylinders on the plane, with spherical and cylindrical shapes. The working pressures of these gas cylinders are very high, some are as high as 45MPa. In order to meet this pressure requirement and reduce the weight of the gas cylinders, the structure of these gas cylinders is made of metal material lining and external winding composite material, and the metal lining is stainless steel, titanium alloy and Aluminum alloy. The traditional manufacturing method for the lining of spherical and cylindrical gas cylinders is a forging machine, that is, forging a cylindrical blank with a wall thickness of about 30mm. After CNC machining, the wall thickness of the final part is 1.5~2.5mm, and the material utilization rate is about 3. %, material waste is serious, processing cycle is long, and manufacturing cost is high. Due to the large thickness of the forging wall, the internal structure often appears uneven, and the mechanical processing destroys the integrity of the metal fiber flow direction, reducing the fatigue life of the product. The gas cylinder lining is formed by strong spinning. The sheet blank can be formed by strong spinning for 1 to 2 times to obtain the required shape and size, which greatly reduces or even eliminates mechanical processing, and improves the life of the lining product; The gas cylinder, assisted by the ordinary spinning and closing process, can also achieve the overall formation of the gas cylinder lining, the entire gas cylinder lining has no welds, and the material utilization rate can reach more than 90%.

Spinning forming of difficult-to-deform materials such as titanium alloys and high-temperature alloys

For decades, spinning materials have concentrated on non-ferrous metals such as low-carbon steel, stainless steel, aluminum and their alloys. With the rapid development of aerospace industry, the demand for powerful spinning of titanium alloys, high-temperature alloys and other difficult-to-deform materials has gradually increased. . Because titanium alloys have poor plasticity at room temperature and large deformation resistance, it is extremely difficult to perform powerful spinning at room temperature. Domestically, TC4, Ti-15-3 and other materials have been subjected to room temperature powerful spinning experiments, but due to TC4 room temperature Under the influence of low plasticity and various process parameters, the test pieces have cracks or other serious defects.

The titanium alloy material adopts hot spinning, which overcomes the problem of huge deformation resistance of titanium alloy at room temperature, and the parts rebound severely. It solves the problem of serious work hardening and difficult to eliminate. It can realize the small and medium-sized titanium alloy thin-walled rotating parts. Stable mass production. There are many titanium alloy cylindrical, tapered and other special-shaped parts in aircraft engines and missiles. In the past, they were formed by reel welding. For example, a certain type of part is now formed by coil welding of TC1 sheet with a thickness of 1.2mm; if Replacing TC1 with TC4 can make the workpiece obtain better strength and heat resistance, and at the same time, because of the increase in strength, the design wall thickness can be reduced to achieve the purpose of weight reduction; secondly, the strong spinning process is used to replace the coil welding forming difficult to deform TC4 avoids the defects caused by the busbar welding seam, and also refines the material grain and improves the strength, which can further reduce the wall thickness and reduce the weight. At present, in some models, in order to meet the requirements of weight reduction and supersonic flight for heat resistance, the spinning parts of titanium alloy have been considered to replace the original aluminum alloy and high-strength steel spinning parts.

High temperature alloys are mostly solid solution strengthened nickel-based anti-oxidation alloys, which have good plasticity and medium thermal strength below 900 ¡æ, and are suitable for manufacturing engine main combustion chambers, afterburner components and guide vanes that work for a long time below 900 ¡æ Wait. However, the material has greater resistance to deformation at room temperature, and the parts have serious springback. For high-temperature alloy thin-walled rotating parts, traditional coil welding and forging methods have the disadvantages of low strength, poor reliability, and waste of materials. Spinning is used. These shortcomings can be effectively avoided. Pay close attention to the microstructure and performance characteristics of the material when the superalloy is strong spinning, and arrange the strong spinning process together. Through the proper annealing process of the blank, a suitable blank for spinning can be obtained. Combining process test and computer numerical simulation technology and theoretical analysis, Optimize spinning process and process parameters; analyze the structure and performance of finished parts. Summarize the law between the spinning forming process parameters of superalloy and the geometry and structure properties of finished parts. The control of the heating temperature of the superalloy material during the spinning process is particularly important. The spinning temperature is too low, the parts are not attached to the mold, and the material deformation resistance is extremely large. The edges of the blank sheet are prone to cracks and other defects, and even the blank is cracked, resulting in the blank scrapped.

A preliminary exploration has been made on the spinning forming of magnesium alloys in China. The crystal structure of magnesium alloy is a close-packed hexagonal structure with few sliding surfaces, and plastic forming is difficult at room temperature. At present, the forming of magnesium alloys is mainly based on casting, especially die casting, and the formed parts have simple shapes and low dimensional accuracy. However, the plastic forming performance of magnesium alloys is significantly improved above the recrystallization temperature. Because the forming temperature range is very narrow, and the spinning forming is carried out in an open large space, the spinning forming of magnesium alloys is more difficult and has more advantages. challenge. The domestic process of magnesium alloy spinning forming has been explored, and the best preheating temperature and forming temperature for magnesium alloy spinning forming have been explored. The thinning rate of magnesium alloy at different temperatures, the feed speed of the spinning wheel, and the spinning The spindle speed of the machine tool was subjected to a process test, and the influence of different forming temperatures on the mechanical properties of magnesium alloys was summarized, and the influence of different temperatures and different forming process parameters on the microstructure of magnesium alloys.

Titanium aluminum alloy is a new type of material that is becoming more and more mature and more and more used. This type of material has been initially used in aero engines. Ti2AlNb is an advanced material. The alloy is a TiAl-based intermetallic compound developed in the past ten years. Compared with high-temperature titanium alloys, this alloy has higher service temperature, creep resistance and high-temperature strength, and its density and thermal expansion coefficient are significantly lower. Based on nickel-based superalloys, it is the first choice for high-performance engines with high temperature resistance and lightweight materials. This kind of material has low plasticity at room temperature and must be formed at high temperature, and the forming temperature range is relatively narrow, which makes heating and temperature control difficult. The current forming method of this kind of parts is mainly forging machine and forming. The material waste is serious and it is not beneficial to the improvement of the structure and performance of the parts. The spinning forming process of this kind of material has been explored in China, and the spinning temperature and spinning The microstructure and properties of the material after pressing were determined, which laid a good foundation for the wide application of thin-walled rotary parts of this type of material in engines.