CNC machine tools are industrial master machines, machines that produce machines. From daily life products such as mobile phones, watches, and computers to high-precision equipment such as airplanes, rockets, and aircraft carriers, almost everything is inseparable from CNC machine tools. It can be said that there is no industry without machine tools.

The 14th Municipal Party Congress pointed out that in order to build a modern new Changsha in an all-round way, it is necessary to consolidate the "ballast stone" of advanced manufacturing industry and speed up the building of an important national advanced manufacturing center. To build a world-class industrial cluster around construction machinery, the importance of CNC machine tools is self-evident. The second report in the series of "Entering the Key Technology Research Site" focuses on the major science and technology project "Research and Application of Key Technologies for High-efficiency Precision Grinding and Polishing" undertaken by Yuhuan CNC Machine Tool Co., Ltd ". The reporter deeply felt at the scene that the scientific research of high-end CNC machine tools is not only the embodiment of the strength of the country's high-end manufacturing industry, but also the ultimate pursuit of beauty.

Field: a machine tool is a production line

Autumn in Changsha, the sun is shining. The reporter drove to Yuhuan CNC, located in Liuyang Economic Development Zone, and saw the modern factory building clean and bright and the machines busy.

In the new product testing area, engineers and technicians are discussing processing details around a CNC machine tool. On the other side, a YH2M8590 five-axis CNC multi-surface grinding and polishing machine is being tested under the supervision of technicians. Reporters saw that the polishing machine tool simulates the frame models of five mobile phones at the same time, and will automatically transfer to the next process after one process is completed.

"The five-axis numerical control multi-surface grinding and polishing machine tool is the latest achievement of the project. What we can see directly now is that the new manufacturing process developed by the project integrates the processing procedures of multiple surfaces of the middle frame of the mobile phone, I .e. integrating four processing procedures of grinding (removing tool marks), rough throwing, semi-fine throwing and fine throwing on one machine tool. A machine tool is equivalent to a production line in the past, which is far superior to traditional technology and equipment in terms of grinding and polishing accuracy, production efficiency, and automation level. It integrates a number of core technologies of independent innovation, and the same type of machine tools have not been found at home and abroad." Yuhuan CNC Engineering Technology Research Institute President, project chief expert Zhou Zhixiong introduced.

Before this kind of machine tool was put into use, the traditional processing methods of mobile phone middle frame were: grinding (removing tool marks), rough throwing, semi-fine throwing, fine throwing and other processing processes. Each process required one machine tool, at least three to five machine tools were required to complete the whole processing, and only one workpiece could be processed at a time. The project has carried out technical integration of the process, greatly improving the processing efficiency and reducing the cost of equipment, land and labor.

In the laboratory a few meters away, a series of large-scale equipment are neatly arranged, and technicians test the key core components of the CNC machine tool. Whether the processed parts are OK or not and the precision symbol does not meet the requirements need to go through several tests here. "This is the double-sided grinding and polishing machine that can exert the greatest pressure at home and abroad. It is specially developed for processing high-hardness materials such as sapphire." Zhou Zhixiong pointed to a high-precision vertical double-sided grinding and polishing machine told reporters.

Story: Focus on tackling key problems often lasts for several months, and the research team's laboratory turns around.

Lightweight mobile phone, light modeling has so many problems? In the face of the reporter's doubts, Zhou Zhixiong took his own use of the curved screen mobile phone explained that, as people's pursuit of beauty is getting higher and higher, mobile phone panels, middle frame, shell, etc. continue to use new materials, such as sapphire, ceramics, new glass, their strength and hardness, brittle; in the shape of the design, from the plane to 2.5D curved surface to 3D surface. When these materials are processed as thin parts, it is difficult to ensure that the force is not deformed or broken, and the "three highs" (high machining accuracy, high surface quality, and high efficiency) guarantee is even more difficult.

"New materials trigger a new revolution in processing technology, and the world does not have processes and machine tools that can effectively solve these problems, so what should we do? We will develop it ourselves, jointly with Hunan University and others to carry out projects to tackle key common technologies such as difficult-to-machine material processing technology, surface precision polishing control technology, multi-axis synchronous control technology, and machine tool structure design." Zhou Zhixiong said.

Scientific research must not be slow and must not wait. On the third day of the first month of 2020, Xu Shixiong, chairman of Yuhuan CNC, as the project leader, led the team to the company to start a protracted war. At that time, the team developed a new integrated manufacturing process, but how to achieve it through machine tools is a big problem.

"Everyone worked overtime in the office and laboratory for two or three months in a row, going in at 8 a.m. and coming out at 12 p.m. and taking a nap to continue working when they were sleepy. In the end, the problem was successfully solved, a number of new technologies were developed, and the problem of making it difficult to ensure consistency requirements for the processing of multiple faces on one machine tool was also solved." Zhou Zhixiong told reporters that as soon as the project achievement "five-axis CNC multi-station polishing machine" was developed, it was applied to the production of iPhone12 mobile phones, and a large number of orders were obtained, and the sales revenue exceeded 0.2 billion yuan in the first year.

In fact, Yuhuan CNC, relying on its core competitiveness in the field of precision grinding and polishing, has been working closely with Apple since iPhone4, including the grinding and polishing of glass panels, back covers and metal frames.

Results: A number of achievements have reached the international advanced level, filling the gap in the industry

my country's CNC machine tool production capacity and consumer market scale are the world's leading, but there are certain shortcomings in the field of high-end CNC machine tools, which has become a pain point restricting the development of my country's manufacturing industry. Yuhuan CNC aims at this demand, and the high-end CNC machine tool products developed are not only leading in the domestic industry, but also exported to many countries.

As the person in charge of the company, Xu Shixiong has been deeply involved in the CNC machine tool industry for more than 40 years, and he is present in every major technological breakthrough of the company. Now, under his leadership, the project "Research and Application of Key Technologies for High-efficiency Precision Grinding and Polishing" takes the stainless steel middle frame and glass front and back covers of smart phones as processing objects, and has developed five-axis CNC multi-surface grinding and polishing machine tools and YH2M8608D 3D concave polishing machine products, all of which have passed the evaluation of scientific and technological achievements organized by Hunan Machinery Industry Association. It is agreed that "the overall technology of the product has reached the international advanced level, A number of key technologies are at the international leading level".

Among them, the five-axis CNC multi-surface grinding and polishing machine tool fills the domestic (international) gap of multi-surface grinding and polishing machine tool, and the control software developed simultaneously meets the needs of mass production and solves the problems of long supply time, untimely service and high price of foreign control system.

"As the chairman unit of Hunan Machine Tool Industry Association and the chairman unit of Changsha CNC Equipment Industry Technology Innovation Strategic Alliance, we should have more responsibilities to vigorously develop the high-end CNC machine tool industry and accelerate the creation of an important national advanced manufacturing center. Now we are preparing to set up a research institute to contribute more." Xu Shixiong revealed that the next step will be to make use of the advantages in the field of precision grinding and polishing technology, docking with relevant colleges and universities, industry-university-research combination to tackle key problems and create new brilliance.