With the development of high-speed cutting technology, the application of high-speed milling technology is becoming more and more widespread, and it has attracted more and more attention from manufacturing enterprises and scientific researchers. After a research institute of the Ministry of Information Industry purchased the first HSM-700 high-speed vertical milling center from the Swiss MIKRON company in July 1999, it purchased three more HSM-700 high-speed milling machines in October 2001 for production. The author conducted in-depth and detailed investigation and research on the processing efficiency of this batch of advanced high-speed milling machines, compared the processing efficiency of different milling machines, and derived the calculation formula of high-speed milling processing efficiency.

1 Calculation of processing efficiency

According to traditional cutting theory, cutting efficiency ZW (cm3/min) can be calculated by the following formula: ZW=v·f·ap (1)

In the formula v————cutting speed

f——feed amount

ap——cutting depth

According to analysis and research, we believe that formula (1) is not suitable for calculating high-speed milling efficiency. There are two main reasons:

The spindle speed of a high-speed milling machine is quite high (for example, the HSM-700 high-speed milling machine has a maximum speed of 42,000r/min, and the speed when processing flat surfaces is also above 35,000r/min). Such a high speed means that the tool is not cutting metal every revolution. ;

In actual machining, the set speed and feed are only the maximum speed and feed, and the actual tool speed and feed are changing all the time (the self-test function of the HSM-700 machine tool can display the conditions during the entire cutting process. Changes), the actual rotation speed and feed rate during the cutting process always quickly reach from a lower value to a higher value and then quickly drop to a lower value. Such repeated changes are an objective reflection of the milling process, unlike turning. The rotation speed and feed rate can be kept constant during the process.

Therefore, we propose to use the metal removal amount Z (cm3/min) per unit time to express the processing efficiency, that is, Z= W

It can be seen from the calculation results that after considering cost factors, high-speed milling no longer has a significant efficiency advantage (close to the processing efficiency of imported ordinary milling centers). This comparison shows that the current cost of high-speed milling is still relatively high (its equipment costs, maintenance costs and tool wear costs are much higher than ordinary machine tools).

Although the current use of high-speed milling cannot achieve economical cutting efficiency, it does not mean that high-speed milling does not have advantages. First of all, the above analysis of the economics of milling efficiency only considers production costs and does not consider time benefits. Today, with the rapid development of technology, time is often a more important economic factor. The advantages of high-speed milling in shortening processing time are obvious. Secondly, the machining efficiency comparison made above is based on the premise that both high-speed milling machines and ordinary milling machines can process the same kind of parts. In fact, many parts are not suitable (or cannot) be processed on ordinary milling machines (such as thin-walled parts or opposite parts). Parts with higher surface quality requirements can only be processed with high-speed milling machines. Third, as a new processing technology, high-speed milling technology is undergoing a continuous development process in our country. In order to obtain the economic processing efficiency of high-speed milling, it is necessary to conduct in-depth research on the high-speed milling mechanism, accelerate the scientific research and development of high-speed milling technology, and at the same time strengthen production. management and improve the quality of operators. It is believed that with the continuous deepening of research on high-speed milling technology, issues such as the economics of processing will be well solved.

4 Conclusion

Production practice shows that high-speed milling machines have a wide coverage of processed parts and are especially suitable for processing precision parts with large areas and complex shapes. The parts are processed with high precision and the scrap rate is low.

The traditional cutting efficiency formula is not suitable for high-speed milling. It is more accurate to express the processing efficiency of high-speed milling by the amount of metal removed per unit time.

From the perspective of the cutting efficiency of machine tools alone, high-speed milling machines are several times higher than ordinary milling machines, but the current cost of using high-speed milling machines is relatively high. When choosing a process solution, you can consider using an ordinary milling machine for rough machining and a high-speed milling machine for semi-finishing and finishing.

Only by carrying out in-depth scientific research and development of high-speed milling technology can the processing efficiency advantages of high-speed milling machines be fully utilized.