The structural characteristics of CNC vertical lathe are as follows:

1. Vertical design: CNC vertical lathe adopts vertical design, the main shaft is perpendicular to the work table, which makes the workpiece clamping and processing process more stable. The vertical design is also conducive to the discharge of cutting chips and coolant, reducing interference to the machining process.
2. Rigid structure: CNC vertical lathe usually adopts solid cast iron or welded structure to ensure sufficient rigidity and stability. This structure can withstand large cutting force and vibration, thus ensuring the precision and quality of processing.
3. Large diameter spindle and worktable: The spindle and worktable of CNC vertical lathe usually have a larger diameter to meet the processing needs of large workpieces. This increases rigidity, improves workpiece stability, and facilitates machining of larger dimensions.
4. Automation system: CNC vertical lathe is equipped with advanced automation system, including CNC control system, automatic tool change system, automatic workpiece measurement and feedback control system, etc. These systems make the operation more convenient and precise, and improve the automation level and production efficiency of processing.
5. Multi-axis control: CNC vertical lathes usually have a multi-axis control function, which can simultaneously control the movement of multiple axes such as the spindle, feed axis and tool holder. This multi-axis control can realize complex machining operations and improve the diversity and flexibility of machining.
6. Tool holder and tool system: The CNC vertical lathe is equipped with a tool holder and tool system with multiple tool positions, which can switch and adjust tools quickly and accurately. This allows users to select appropriate tools based on actual machining tasks and perform efficient cutting operations during the machining process.

It should be noted that different brands and models of CNC vertical lathes may have some subtle structural differences, and the specific structural characteristics may be different. But in general, CNC vertical lathes have the above characteristics to meet the high-precision processing needs of large workpieces.