What are the forging process optimization of hollow shaft?

Comparing the bending and torsion cross-section coefficients of the hollow shaft and the solid shaft, it is found that the hollow shaft and the solid shaft with the same outer diameter have little difference in the transmission torque, bending moment and bending and torsion, but the hollow shaft can greatly reduce the weight of the shaft. Therefore, the application of the hollow shaft has been paid more and more attention, and it is urgent to solve the forming problem of the hollow shaft. The forming methods of hollow shaft are summarized, and the principles and characteristics of forging machining, radial forging, rotary forging, extrusion or extrusion machining, cross wedge rolling, power spinning, rotary compression, internal high pressure forming, cross rolling axial punching, injection forging, and hydrostatic extrusion internal high pressure forming are briefly analyzed. Several common forming methods are compared in terms of blank shape, forming temperature, lubrication, forming pass and size. In the future, the demand for hollow shaft will be more and more, and the forming method will develop in the direction of flexibility.

Mechanical transmission devices exist in almost all mechanical products, and different transmission mechanisms or devices have different requirements. For example, some need a large transmission ratio of the deceleration mechanism, some need a longer drive shaft, and some need to reduce their own weight, the use of hollow shaft transmission. In mechanical manufacturing, reducing weight and saving materials is one of the goals that almost every designer wants to pursue.

The hollow shaft is one of the important parts of the machine. Various transmission parts that do rotary motion support the transmission parts and transmit motion and power through the shaft. According to the different loads on the shaft, the hollow shaft can be divided into: the main shaft that only bears bending moment and does not transmit torque, such as the axle of high-speed rail; the transmission shaft that only transmits torque and does not bear bending moment, such as the transmission shaft of an automobile; the transmission torque and The rotating shaft that bears the bending moment, such as the automobile gearbox shaft. For hollow shafts whose other forces are negligible compared to their torque, it is necessary to design them hollow from the point of view of weight reduction and material saving. Since the shear stress on the cross-section is linearly distributed along the radius, the stress near the center of the circle is very small, that is, the material near the center of the circle does not perform as it should. This theory has long been known and widely used. For example, transmission hollow shafts of some transport machines such as airplanes, ships and automobiles are designed to be hollow in order to reduce their mass. However, according to the traditional design methods and techniques, it is impossible to achieve quality while meeting the use intensity, because the calculation of this design is very large, and it is almost impossible to complete the original manual calculation. Only in today's highly developed computer technology and software technology, can we solve the high-order equations that are difficult to calculate manually and realize the design scheme.