The mandrel is used to support the rotating parts only bearing the bending moment without transmitting torque, and is divided into a rotating mandrel and a fixed mandrel.
Mandrels are used to support rotating parts that only bear bending moments without transmitting torque. Some mandrels rotate, such as the axles of railway vehicles, and some mandrels do not rotate, such as the shafts that support pulleys. The mandrel can be divided into a rotating mandrel and a fixed mandrel according to whether the shaft is rotating or not: Rotating mandrel: The bearing is subject to bending moments and the shaft rotates during operation; Fixed mandrel: The bearing is subject to bending moments and the shaft is fixed during operation. According to the role played by the shaft and the load it bears, it can be divided into a mandrel, a rotating shaft and a transmission shaft: its central shaft: only bears the bending moment and does not transmit torque; the rotating shaft receives both bending moment and torque; the transmission shaft only transmits torque Without bearing the bending moment, or the bending moment is very small.
Commonly used mandrels are: 1. Small taper mandrel, small taper mandrel has higher positioning accuracy. However, the small taper mandrel is not convenient for loading and unloading workpieces, and cannot be positioned in the axial direction, so it is only suitable for workpieces with small batches, high accuracy, and no positioning requirements in the axial direction; 2. The stepped mandrel with nut pressing is suitable for clamping multiple workpieces and occasions where the accuracy of the workpiece is not too high; 3, the expansion mandrel, because of convenient loading and unloading of the workpiece, high accuracy, suitable for sleeve parts with larger bore tolerances.
1. The mandrel and the hole maintain a large contact surface, and the positioning accuracy is high; 2. Using the elastic deformation of the spring sleeve to center the workpiece, the positioning accuracy is high; 3. The fit clearance of the positioning surface affects the positioning accuracy; 4. Using the Pascal principle, the thin-walled sleeve is elastically deformed to center the workpiece, and the positioning accuracy is high, and the coaxiality can reach 5 μm; 5. It can reduce the clamping deformation of the thin-walled sleeve workpiece and improve the processing accuracy; 6. There is a positioning interference of 0.002mm to achieve extremely high positioning accuracy.