1000/1000
Hot
Most Recent
There is no comment~
More
High-speed motorized spindles tend to develop in the direction of high precision, high speed, low energy consumption, high efficiency, and high reliability.
As modern machine tools are developing towards high speed and high precision, the technical requirements for the spindles of machine tools are increasing. The motorized spindle is one of the core functional components of high-speed machine tools; the motor of a motorized spindle is placed inside the spindle unit of the machine tool to drive the spindle. Therefore, the machine drive structure is simplified, and “zero drive” is achieved [1][2]. Because the motorized spindle has the advantages of its compact structure, is lightweight, has small inertia and good dynamic performance, the dynamic balance of the machine tool is improved and the vibration and noise are avoided. The structure of traditional rolling bearings makes it difficult to meet the requirements of high speed and high precision for high-speed machine tools, so the research of bearings is one of the key research objects in the field of high-speed machine tools [3]. As the key support technology for high-speed motorized spindles, bearings must meet the requirements of high-speed operation, and have high rotary accuracy and low-temperature rise, in addition to long service life, especially with regard to maintaining the accuracy. The current high-speed motorized spindle applied bearings are mainly angular contact ball bearings, liquid floating bearings, air bearings, and magnetic bearings. But the speed and precision of the spindle-bearing improvement is based on the premise of high-precision dynamic balance. For motorized spindles, the unbalance phenomenon is inevitable due to the influence of factors such as manufacturing, installation error, and material unevenness.
Figure 1. Analysis diagram of high-speed electric spindle technology.
The high-speed precision bearing is one of the core supporting components of a high-speed motorized spindle. Bearings are often in high-speed or ultra-high-speed operation, so the bearings must have a series of characteristics such as good high-speed performance, high dynamic load-carrying capacity, superior lubrication performance, and low heat generation. At present, high-speed precision bearings have become the key research and development technology in the world. There are four main types of bearings for high-speed spindles, including angular contact ceramic ball bearings, liquid floating bearings, air bearings, and magnetic bearings. The specific classification is shown in Figure 2 [4]. In addition, after extensive literature research, surveys are presented in this section and summarized in Table 1.
The thermal error prediction model of the high-speed motorized spindle is the core of the thermal error compensation system. Using temperature data to predict the change of thermal displacement, the establishment of the thermal error compensation system. In the study of thermal error modeling of high-speed motorized spindles, researchers have widely used the multiple regression method, gray theory and neural network method. In this section, the research results related to thermal error modeling are presented and summarized in Table 4.
With the rapid development of high-speed cutting, CNC technology and the needs of practical applications, the performance of the high-speed motorized spindle of CNC machine tools has put forward higher and higher requirements. Based on the analysis of the key technologies of the high-speed motorized spindle, the research direction of high-speed motorized spindle unit technology is summarized. The main aspects are as follows.
(3) To improve the running accuracy of the motorized spindle, the research on the generalization of dynamic balancing technology, using a dynamic balancing method that capable to balance the rigid spindle and flexible spindle at the same time, which would help to reduce the impact of vibration on the high-speed motorized spindle, must be accelerated.
(4) To reduce the influence of heat generation and thermal error of the spindle, and improve the accuracy of the spindle, research on the application of computer simulation technology in the design of high-speed motorized spindles must be strengthened, and the development of highly reliable modeling methods to realize the compensation of errors must be achieved.