Application of Precision Ball Screw in CNC Machine Tools

Precision ball screw is a kind of screw transmission, specifically, it is a rolling screw transmission. Ball screw consists of screw, nut and ball, and its working principle is to use the rolling of ball between screw and nut to realize the conversion and transmission of motion.
The application of ball screw in CNC machine tools is mainly reflected in the following aspects:

1. Axial Transmission and Radial Clearance

The clearance refers to the gap between the ball screw nut and the screw. Although this gap is usually kept in a small range during design, it still has a certain impact on the dynamic response of the machine tool. When the gap is large, it may cause the machine tool to produce greater vibration during the cutting process, which in turn affects the processing quality of the workpiece, especially in high-precision processing. Although too small a gap can improve the transmission accuracy, it may cause increased friction of the screw and generate higher heat, thereby affecting the working performance and service life of the screw. Therefore, precision ball screws are usually used to control the axial movement of tools, workpiece tables and other components on CNC machine tools. For example, it is used to control the up and down movement of tools on milling machines and the feed movement of tools on lathes.

2. High-Speed Motion

The transmission efficiency of precision ball screws is very high. Compared with ordinary sliding screws, ball screws have lower energy loss due to their rolling friction characteristics. High-speed CNC machine tools need to bear a large amount of motion load during operation, and the energy loss of traditional screws is large, resulting in low system efficiency. The ball screw can transmit more power to the workpiece through the continuous rolling of the ball, which greatly improves the transmission efficiency of the machine tool and reduces energy waste. This is undoubtedly an important advantage for modern manufacturing industries that require efficient production.

3. High-Precision Processing

Ball screws can provide high accuracy and repeatability, so they are widely used in CNC machine tools that require high-precision processing. For example, CNC lathes and CNC milling machines that need to process precision parts.

4. CNC Cutting

Precision ball screws are also often used in CNC cutting equipment, such as laser cutting machines, plasma cutting machines, etc., to control the up and down movement of the cutting head to achieve precise cutting of the workpiece.

5. Achieve Precise Linear Motion of Tools or Workpieces

In CNC machine tools, ball screws are used to achieve precise linear motion of tools or workpieces, ensuring machining accuracy and surface quality.

6. Improve Efficiency and Accuracy

The rigidity and thermal stability of precision ball screws are key factors in improving positioning accuracy. Under high load conditions, the deformation of the screw directly affects the positioning accuracy. Manufacturers usually choose high-strength materials such as alloy steel or stainless steel to increase the bearing capacity of the screw and reduce deformation caused by material fatigue. In addition, by optimizing the support and fixing methods of the screw, the external load can be effectively dispersed and the influence of deformation on positioning accuracy can be reduced.
During the operation of CNC machine tools, the temperature of the screw may rise due to friction and heat generated during cutting, which in turn affects the material properties and dimensional changes, causing positioning errors. Therefore, good thermal management measures are necessary to ensure efficient and stable operation of ball screws. Many high-end CNC machine tools are equipped with cooling systems to maintain the stability of the screw by controlling the temperature of the working environment.

7. Installation Method

The installation methods of precision ball screws include fixed-support, fixed-fixed, supported-supported, and fixed-free modes. Different screw installation methods have a significant impact on the rigidity, stability, precision and service life of CNC machine tools. Choosing the right installation method can optimize the performance of the machine tool and meet specific processing requirements. When designing, the most suitable screw installation method should be selected according to the specific application, load requirements and working environment of the machine tool.

8. Preload and Clearance Adjustment

In order to improve the rigidity and precision of the ball screw feed system, it is very effective to pre-stretch the screw shaft. At the same time, there are three main methods for adjusting the clearance of ball screws: shim clearance type, thread clearance type, and tooth difference adjustment type, which help to ensure the high precision requirements of machine tools.

Summary

Precision ball screws play an important role in CNC machine tools. They are not only used to achieve precise linear motion, but also help to improve the processing efficiency and precision of machine tools.