The spindle of a CNC vertical lathe, as the core moving component, directly determines the machining accuracy and efficiency based on its performance. According to different structural designs and power transmission methods, common spindle types can be divided into mechanical transmission spindle, electric spindle, and hydraulic spindle, and there are significant differences in their working principles.
Mechanical transmission spindle is the mainstream configuration of traditional vertical lathes, and its core lies in power transmission through multi-stage gears or belts. After the torque output by the motor is variable by the gearbox, it drives the main shaft to rotate through the transmission shaft. The gear mesh clearance and belt tension directly affect the transmission accuracy. The advantage of this type of spindle is its strong load-bearing capacity, which can adapt to different speed requirements through gear shifting. It can provide stable low-speed high torque when machining heavy workpieces. However, friction and vibration in the mechanical transmission process can limit its maximum speed, and regular replacement of gear lubricating oil and belts is required during maintenance.
The electric spindle integrates the motor and spindle into one, eliminating the traditional mechanical transmission structure. Its working principle is based on direct electromagnetic induction drive. The stator winding generates a rotating magnetic field, which drives the permanent magnet rotor to rotate synchronously with the spindle. The speed control is achieved through variable frequency technology for stepless adjustment. Due to the reduction of intermediate transmission links, the dynamic response speed of the electric spindle is greatly improved, making it easy to achieve high-speed operation of tens of thousands of revolutions, suitable for high-speed cutting of precision parts. At the same time, the integrated design reduces vibration and noise, but due to the limited heat dissipation capacity of the motor, its ability to sustain heavy loads is weak, and it is mostly used in precision machining scenarios with medium loads.
The hydraulic spindle is driven by a hydraulic system, and its working principle is based on Pascal's law. The pressure oil generated by the hydraulic pump enters the main shaft cylinder, pushing the piston to drive the main shaft to rotate. The speed and torque are controlled by adjusting the hydraulic flow rate and pressure. The advantage of this type of spindle lies in its uniform output torque, which can absorb cutting impacts through the buffering effect of hydraulic oil, and perform stably when machining brittle materials or performing intermittent cutting. In addition, the stepless speed regulation characteristics of hydraulic transmission enable it to maintain constant torque over a wide range of speeds. However, the risk of leakage and oil contamination in hydraulic systems pose higher maintenance requirements and are commonly used in heavy-duty machining fields that require high torque stability.
The difference between the three types of spindles is essentially the choice of power transmission method: mechanical transmission focuses on gear meshing, pursuing heavy-duty and speed flexibility; Electric spindles are characterized by direct electromagnetic drive, with a focus on high speed and precision; The hydraulic spindle relies on fluid pressure transmission, emphasizing torque stability and impact buffering. Understanding the differences in these principles can help to make reasonable selections based on processing requirements, while ensuring processing quality and improving production efficiency.