Overview of the development of American machine tools and analysis of future development trends

The successive governments of the United States have attached great importance to the machine tool industry. The US Department of Defense and other departments have continuously proposed the development direction and scientific research tasks of the machine tools because of their military needs, and provided sufficient funds. At the same time, they have gathered talents from the world, especially in the development. And "innovation", focusing on basic research. Machine tool technology continues to innovate, such as the world's first CNC machine tool developed in 1952, the machining center created in 1958, the FMS developed in the early 1970s, and the first open CNC system in 1987. Since the United States firstly combined the production requirements of automobiles and bearings, it has fully developed a large number of automatic lines required for production automation, and the electronics and computer technology are leading in the world. Therefore, the design, manufacturing and numerical control system of the CNC machine tools are solid and consistent. Scientific research and innovation, so its high-performance CNC machine technology has also been leading the world. However, its shortcomings are that it emphasizes basic research and neglects applied technology. In addition, the government-guided relaxation in the 1980s caused the growth of CNC machine tool production to slow down. In 1982, it was overtaken by Japan, and imported in large quantities. Since the 1990s, the government has corrected the past bias, and CNC machine tools have turned from technology to utility, and production has gradually picked up.

The US machine tool industry started 50 years later than the UK, but soon surpassed the UK in manufacturing technology, ranking first in the world. In 1896, Ford built the first car. In order to cope with the mass production of the car, Gleason developed a complete set of equipment and tools for gear processing and measurement. Other companies have also developed many new and efficient automatic machine tools. In 1934, the world's first automatic line of combined machine tools was developed. In 1948, the world's first automatic line with an annual output of 30 million sets of bearings was established, which led to a rapid increase in vehicle production. In 1950, the output of automobiles reached 8 million (compared with 2.07 million in China in 2000). Since then, the US machine tool industry has developed rapidly, ranking first in the world for machine tool technology advancement, production, and production scale. Although in the mid-1980s, the US economy was in recession, the machine tool industry was once in a downturn and was overtaken by Japan and Germany. However, the government quickly took measures to reverse the situation.

At present, the US machine tool manufacturing industry is still in the world's leading position in high-efficiency automated machine tools, automatic production lines, NC machine tools, FMS and other machine tool technologies and industrial production. Mainly distributed in the Midwest and Northeastern states, the main consumer users are automobile manufacturing, aviation industry, construction industry and medical equipment manufacturing.

The reason why the US machine tool technology can maintain a long-term lead in the world, the government has played a vital role in guiding the strengthening of research and development and continuous innovation. Mainly manifested in:

First of all, plan, measure and provide adequate funding for major scientific research projects. For example, it provides a lot of money for the research and development of NC machine tools. Providing $100 million in funding for the development of a new generation of NC systems.

Second, the organization guides scientific research cooperation between relevant research units and enterprises. For example, the development of a new generation of NC systems was developed by the National Manufacturing Science Center in collaboration with the US Air Force; the development of CIM, the government organization General Motors, Boeing Aircraft Corporation and related machine tool industry companies jointly developed.

Once again, after the new products are developed, organize the use of orders and promote the further deepening of scientific research. For example, after the first NC milling machine was developed by the Massachusetts Institute of Technology in 1952, the military department immediately ordered 100 units for production and continuous improvement, thereby accelerating the continuous improvement of NC machine tool technology. Another example: After the United States G&L Company developed the world's first VARLA4 parallel mechanism machine tool in 1994, it timely organized relevant university research and analysis and used it in the enterprise to further improve its technology.

Due to the lack of skilled workers in the United States and the relatively high wages of workers, machine tool users demand that machine tool builders have more flexible machine tools and can be programmed repeatedly to reduce the need for skilled workers. Due to the increasingly fierce competition in the automotive industry, the vehicle model renewal cycle is also getting shorter and shorter. The automotive industry requires flexible performance, wide range of use, and short commissioning cycle to meet the requirements of small batch production and fast replacement.

The demand for high-speed machine tools in the US aviation, automotive and mold industries is increasing. Due to environmental reasons, many customers require machine tools to reduce the amount of coolant used. All of the above shows that technological advancement is the main factor affecting the development of the US machine tool industry.
For example, electronic, high-speed, and precision have become the mainstream of the development of the US machine tool industry: for example, American companies can effectively integrate suppliers and customers' procurement and inventory systems through network enterprise-to-business services; large-scale automobile companies (GM, Ford, Dai Mühler/Chrysler and Aerospace (boeing, Lockheed) are designed and developed on a global scale with related systems through this network service; manufacturing process management, remote monitoring, troubleshooting and after-sales service in the machine tool industry are gradually becoming more and more Popularization; the milling machine spindle adopts hydraulic bearing molds, and uses non-contact replacement ball bearings; linear motors get rid of application restrictions and enter commercialization.

Looking at the future, the US machine tool manufacturing has the following obvious development trends:

First, the pursuit of machine tools with higher processing efficiency. Because improving the efficiency of the machine tool is equivalent to shortening the machining cycle of the part, there are two ways to shorten the machining cycle. One way is to increase the cutting speed, that is, increase the spindle speed. At present, the spindle speed of the lathe and turning center is above 8000r/min, and the spindle speed of the machining center is generally 15000~20000r/min, and there are 40,000r/min and 60,000r/min. Similarly, the delivery speed has been greatly improved, up to 20m/min or even 60m/min. As the cutting speed increases, the structural rigidity and dynamic characteristics of the machine tool are significantly improved, and the dynamic balance design of the high-speed spindle and the tool system is also improved; the other way is to reduce the non-machining time. Because there is a lot of useless time in the processing of parts, such as workpiece handling, loading and unloading, installation adjustment, tool change and spindle lifting and lowering speed, the development of composite machine tools has recently developed rapidly, and its core is in one Various operations such as turning, milling, drilling, boring, tapping, reaming and reaming are required on the machine. The main trend in the development of lathe technology is multi-function machine tools. The current multi-functional machine tool is actually a machining center with turning function. In terms of grinding, the current technical focus is on the development of a PC-based grinding control system. A grinding machine can perform internal, external and step shaft grinding, or it can speed up the production process by different cycles of the machine. Fast and dimensional accuracy and surface roughness are guaranteed.

Second, the pursuit of more safe and reliable and environmentally friendly machine tools. Due to the increased speed of the machine tool, the safety and health of the operator has also been mentioned as a priority. At present, high-end machine tools developed in the United States almost always have safety warning devices in places that may harm people. Dry cutting and micro-lubricant cutting methods are becoming more and more widely used because they can greatly reduce the volatilization of lubricants, and almost all machine tools are closed. Some machines can't even see the chips, so even if there are Excessive oil mist and fumes are also easy to collect. At the same time, the environment and position of the machine operator at work will be considered very comfortable. In addition, non-polluting clean processing technology has also received great attention.

Third, the machine tool component industry has developed rapidly. The machine tool parts are developing rapidly and the variety is complete. The main products are ball screw pair, precision bearings, various turntables, tool changers, various pneumatic, hydraulic devices, linear guides and spindle components. The development of these accessory industries has strongly promoted the development of machine tool mainframes, which not only helps to improve the speed and performance of machine tools, but also greatly shortens the production cycle of the mainframe and reduces production costs.

Fourth, the pursuit of a more complete control system. Higher speed processors and more precise control equipment make the machine's functions and performance perfect and powerful. Technology intensive has entered the stage of rapid development, and the key to integration is open architecture. The application of PCC technology has begun to change the way the machine works, pushing the CNC to the control center and not limited to the scope of the machine controller. Control software is growing faster and even improved several times a year. CNC manufacturers have provided some open-structure CNC systems. At present, CNC controllers with open structures in machinery manufacturing plants account for 10% to 20%.

The part program can be developed offline and then transferred to the programming system on the production floor. It runs on the CNC controller. The operator can observe and test the tool operation and machining process, and can also make necessary corrections to the machining process. 30% of the controllers sold by GEFANUC in the United States are open-ended, realizing true CAM/CNC integration, and tending to be intelligently controlled and accessible. The technical foundations of virtual manufacturing and paperless production are already available, and with the help of information technology, the application of such software will develop at a faster rate.

Fifth, the pursuit of higher machine tool appearance quality. At present, machine tool manufacturers pay more attention to the beauty of machine tool modeling and the harmony of color tone, and the machine tool products are more developed towards crafts.

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